Polycrystalline cubic boron nitride (PCBN) is based on cemented carbide, and a layer of cubic boron nitride (CBN) single crystal fine powder (0.5~1.6mm thick) is placed on it, and the binder is subjected to high temperature (1400~2600 ℃) and high pressure (7~9Gpa) to press the polycrystalline tool material.

Due to the small particle size of single crystal CBN powder and the existence of “cleavage planes” that are easy to split, single crystal CBN powder cannot be directly used to manufacture cutting tools. Therefore, most of the cutting tools used in the industry are polycrystalline cubic boron nitride (PCBN).

PCBN Cutter

                     PCBN Blank and Cutters

1Properties of PCBN

1.1 High Hardness and Excellent Wear Resistance of Cubic Boron Nitride CBN

CBN is artificially synthesized, its hardness is second only to that of diamond, and the grain hardness can reach HV8000~ HV9000, which is much higher than that of ceramics and cemented carbide. The hardness of the PCBN composite sheet (usually HV3000 ~ HV5000) mainly depends on the content of CBN. Generally, the content of CBN is between 40% and 95%. The hardness of PCBN increases with the increase of CBN content. The relationship between wear resistance and CBN content is not a monotonic relationship, and there are different optimal values under different processing conditions. When machining heavy steel molds, when the CBN content is about 55%, the tool is the most wear-resistant.

CBN is artificially synthesized, and its hardness is second only to that of synthetic diamond powder. The grain hardness can reach HV8000~HV9000, which is much higher than that of ceramics and cemented carbide. The hardness of the PCBN composite sheet (usually HV3000 ~ HV5000) mainly depends on the content of CBN. Generally, the content of CBN is between 40% and 95%. The hardness of PCBN increases with the increase of CBN content. The relationship between wear resistance and CBN content is not a monotonic relationship, and there are different optimal values under different processing conditions. When the CBN content of PCBN is about 55%, its tool processing mold heavy steel is the most wear-resistant.

1.2 High Thermal Stability of Cubic boron nitride (CBN

The heat-resistant temperature of cubic boron nitride is as high as 1400 ~ 1500 ℃, which is almost double that of diamond (700-800 ℃). Cubic boron nitride is transformed from cubic crystal to hexagonal crystal and begins to soften when it is above 1370 °C. It can be used to make tools for high-speed cutting of superalloys, and its cutting speed is 3-5 times higher than that of cemented carbide tools.

1.3 Excellent Chemical Stability of Cubic Boron NitrideCBN

Cubic boron nitride is a very chemically inert substance. In neutral reducing gas medium, it is stable to acid and alkali. It only reacts with carbon at above of 2000 °C and does not react with iron group materials at 1200~1300 °C. The bonding and diffusion effects of cubic boron nitride (CBN) and various materials are much smaller than those of cemented carbide, and can be used to cut steel materials that industrial diamond powder cannot cut.

1.4 Excellent Thermal Conductivity of Cubic Boron Nitride

The thermal conductivity of cubic boron nitride is 79.54w/m.k, which is second only to diamond (146.5w/m.k). And with the increase of temperature, the thermal conductivity of cubic boron nitride gradually increases, which is beneficial to the temperature control of the cutting area and the reduction of the diffusion wear of the tool.

1.5 Low Coefficient of Friction of CBN

The friction coefficient between PCBN and different materials is 0.1~0.3. The lower friction coefficient reduces the cutting force, reduces the cutting temperature, and is not easy to generate chips, which is beneficial to improve the surface quality of the processed material.

2. Classification of Polycrystalline Cubic Boron NitridePCBNTool

Polycrystalline cubic boron nitride (PCBN) cutting tools can be divided into Monolithic Polycrystalline Cubic Coron Nitride sintered body (referred to as PCBN sintered body) and polycrystalline cubic boron nitride composite sheet (referred to as PCBN composite blade) and Electroplated cubic boron nitride cutting tools are most widely used with PCBN composite inserts.

PCBN Tools

                           PCBN Tools

3. Application of PCBN Cutters

PCBN is composed of numerous small disordered CBN single crystals, no cleavage plane, macroscopic directionality, which will greatly reduce the effect of splitting, and new crystals are continuously exposed as the cutting tool wears away. PCBN has similar structure and properties with PCD and PDC tool materials, but its wear resistance is worse than that of PCD and PDC. PCBN has good chemical corrosion resistance and shows good thermal stability at the high temperature of 1200℃. Therefore, the high temperature does not have any adverse effect on the PCBN tool tip, on the contrary, it can also play a role in accelerating the cutting of hard iron alloy.

With the continuous development of cutting technology, cubic boron nitride tool is widely used in the machining of high hardness and difficult materials.

3.1 Turning Hard-to-machine Materials with High Hardness by CBN tools

Due to the high hardness and wear resistance of CBN tools, the use of integral PCBN cutting tools can be used for grinding and turning high-hardness and difficult-to-machine materials.

3.2 High Speed and Ultra-high Speed Cutting by PCBN Tools

PCBN tools are most suitable for high-speed cutting of cast iron and hardened steel materials. When the PCBN tool cuts cast iron and hardened steel, it can be seen from the relationship between the tool flank wear and the cutting distance that when the cutting speed exceeds a certain limit, the higher the cutting speed, the smaller the PCBN tool flank wear speed. It means that the life of the tool under high-speed cutting is higher, which is especially suitable for modern high-speed cutting.

Processing  Hardened Steel by PCBN

       Processing Hardened Steel by PCBN

3.3 Dry Cutting by PCBN Tools

CBN tools use dry cutting when machining workpieces, which can reduce environmental pollution. The use of coated or ceramic tools requires wet cutting, and iron filings are not easy to clean. The use of CBN tool can not only cut high-hardness cast iron with a large margin without adding cutting fluid, but also ensure on-site hygiene and facilitate the recycling of iron filings.

3.4 Automatic and Difficult to Process Material Processing by PCBN Tools

PCBN tools have high hardness and wear resistance, which can process high-precision parts for a long time at high cutting speeds, greatly reducing the number of tool changes and the time spent on tool wear compensation downtime. Therefore, PCBN tools are very suitable for CNC machine tools and processing equipment with a high degree of automation, which can fully utilize the high efficiency of the equipment.

Application of PCBN in automatic machining

Application of PCBN in automatic machining

4. Service Life of PCBN Tool

The life of PCBN tools is 3-5 times that of ceramic tools and 5-15 times that of carbide tools. Its high wear resistance and long life greatly improve the machining accuracy of the workpiece, reduce the number of tool changes and sharpening, and improve work efficiency.

In recent years, with the rapid development of CNC (computer numerical control) processing technology and the widespread use of CNC machine tools, the application of PCBN tools that can achieve high efficiency, high stability and long life processing has become increasingly popular. Machining concepts, such as high-speed cutting, hard machining, turning grinding, dry cutting, etc. PCBN tool material has become an indispensable and important tool material in modern machining.

CBN is synthesized from hexagonal boron nitride and a catalyst under high temperature and pressure, and its properties are similar to those of synthetic diamond, and some properties (such as thermal stability) are better than diamond. It has high hardness, thermal stability and chemical inertness, as well as excellent infrared transmittance and wide forbidden band width. Its hardness is second only to diamond, but its thermal stability is much higher than diamond, and it has great chemical stability for processing iron metallic elements.

The grinding performance of cubic boron nitride(CBN) abrasives is very good, not only can it be competent for the processing of difficult-to-grind materials, but also effectively improve the grinding quality of workpieces.

Crystal structure of CBN

                Crystal structure of CBN

  1. The Performance of CBN Powder

1.1 Hardness

The hardness of a substance is related to the atomic spacing of the constituent lattice, and as the atomic spacing decreases, the crystal hardness increases. CBN is 1.57 angstroms, and the shortest distance between diamond atoms is 1.5 angstroms. Therefore, the hardness of CBN (microhardness 71.54GP) is slightly lower than that of diamond powder, but higher than that of the other two main abrasives, silicon carbide (Sic-microhardness 25.48~35.28GPa) and alumina (Al₂O₃-microhardness 17.64~27.44GPa) is much higher.

Using a Knoop hardness tester, the hardness of CBN single crystal in the [100] direction is 4600kg/mm², while that of the diamond is 10000kg/mm². The hardness of CBN single crystal in the [110] direction is 3200kg/mm², while that of the diamond is 7000kg/mm². This shows that the hardness of CBN is anisotropic, and its hardness is slightly lower than that of the synthetic diamond powder.

The superhard materials previously used in production mainly refer to diamond powder and cubic boron nitride powder. Cubic boron nitride and cubic diamond have a common feature that the covalent bond “bond angle” in their structure is 109°28′. It is the 109°28′ covalent bond angle that makes cubic boron nitride and cubic diamond have the highest hardness and is called superhard material.

1.2 Thermal conductivity

Cubic boron nitride has good thermal conductivity. Its thermal conductivity (79.54wm·k) is smaller than that of diamond (146.5w/m·k), but much higher than that of high-speed steel (16.7~25.1w/m·k) and Carbide (20.33~80.77wm·k). With the increase of cutting speed, the thermal conductivity of CBN also increases gradually, which is beneficial to reduce the temperature of the cutting zone and reducing

diffusion wear. At the same time, due to the good thermal conductivity of CBN, its efficacy as a heat sink is second only to that of industrial diamond powder.

1.3 Thermal stability and oxidation resistance

Cubic boron nitride has high thermal stability and can withstand cutting temperatures above 1200 ° C, which is better than diamond. Cubic boron nitride has high hardness and high thermal stability and can be used as a high temperature-resistant material to reduce thermal damage to the workpiece.

The heat resistance of cubic boron nitride is mainly determined by its composition and structure. Although cubic boron nitride has a similar structure to diamond, the carbon atom bonds on the diamond surface are unsaturated. Under the condition of high temperatures above 720 °C, these unsaturated surface carbon atoms are easily combined with oxygen atoms to form carbon oxides and escape. The crystals are gradually peeled off and disintegrated. The surface of the cubic boron nitride crystal is covered by nitrogen and boron atoms, and the electronic layer structure of the boron atom is 1S22S22P1, which can provide three bonding electrons, so that the valence bond of the boron atom on the crystal surface is saturated without dangling bonds, so It is still relatively thermally stable at the diamond oxidation temperature.

Therefore, CBN has high anti-oxidation ability, and no oxidation phenomenon occurs at 1000 °C. In vacuum, the phase transition from CBN to HBN occurs when the temperature reaches 1550 °C.

1.4 Chemically inert

CBN is chemically inert and has high chemical stability to acids and bases in neutral and reducing gas media.

CBN is also chemically resistant to iron, steel and oxidizing environments, forming a thin layer of boron oxide when oxidized. This oxide provides chemical stability to the coating, so it is especially suitable for processing ferrous materials. On the other hand, diamond is different. Steel and iron have a large affinity for carbon, so it is easy to stick chips during grinding, resulting in poor grinding effect.

1.5 Disadvantages of single crystal cubic boron nitride (CBN)

In addition to the above advantages, the single crystal cubic boron nitride grains have the disadvantages of small size and anisotropy, cleavage planes that are easy to split, and high brittleness, which is extremely prone to cleavage damage.


2. The Application of cubic boron nitride (CBN)

Due to its poor compatibility with iron group metals and alloys, cubic boron nitride (CBN) is one of the main tools for processing iron group hard and ductile materials. At present, cubic boron nitride is mainly used in the production of abrasives and PCBN cutting tools.

2.1 Small particle CBN single crystal is mainly used as the abrasive material.

CBN abrasives are products with specific geometric shapes that bond CBN abrasive grains with the help of binders. As a kind of superhard material abrasive tool, CBN abrasive tool is used for grinding, which belongs to the emerging advanced manufacturing technology. It can be used for the processing of iron-based materials and non-ferrous metal materials. The application range of the field is wider than that of diamond abrasive tools.

The cubie Boron Nitride abrasive tool has good grinding performance for ferrous metals, especially for materials with high hardness, toughness, high strength and low thermal conductivity at high temperature, and its metal grinding rate is 10 times that of diamond, which solves the problem of processing hard and tough materials. The cubic boron nitride grinding tool is used in high-speed and efficient grinding and honing, which can greatly improve the grinding efficiency. It has high grinding precision, long grinding wheel life and saves much auxiliary time such as grinding wheel replacement dressing, machine tool adjustment and workpiece inspection.

CBN Grinding Disc and Wheel

            CBN Grinding Disc and Wheel

2.2 CBN can also be used as cutting tools

CBN can also be used as cutting tools, such as drills, turning tools, reamers, and milling cutters, which are used to process tool steel including high-speed steel and die steel, bearing steel, stainless steel, nickel-based alloys and chilled hardened cast iron. In these processing fields, CBN replaces corundum and has achieved good economic results. Especially when processing cemented carbide steel above HRC50, because CBN is sharper than corundum and has more stable performance than diamond, it shows a series of advantages.

PCBN Cutter

                              PCBN Cutter

1. Monocrystalline and polycrystalline silicon

Silicon is a hard and brittle material with a Mohs hardness of 6.5 and can be made into polycrystalline silicon and single crystal silicon according to the application. Monocrystalline silicon is a relatively active non-metallic element. This crystal has a basically complete lattice structure and is a good semiconductor material with a purity of 99.9999%. It is mainly used in the manufacture of semiconductor devices and solar cells. The manufacturing method of single crystal silicon (Fig. 1a) is usually to prepare polycrystalline silicon or amorphous silicon first and then grow rod-shaped single crystal silicon from the melt by the Czochralski method or the floating zone melting method.

Polycrystalline silicon (Fig. 1b) is a form of elemental silicon. When molten elemental silicon solidifies under supercooled conditions, silicon atoms are arranged in the form of diamond lattices into many crystal nuclei, such as these nuclei growing into crystals with different crystal plane orientations. grains and these grains combine to crystallize into polysilicon. Polysilicon is the direct raw material for the production of monocrystalline silicon and is the basic electronic information material for semiconductor devices such as contemporary artificial intelligence, automatic control, information processing, and photoelectric conversion. It is called “the cornerstone of the microelectronics building”.

Monocrystalline and polycrystalline silicon

        Fig.1 Monocrystalline and polycrystalline silicon

Features Monocrystalline silicon  polycrystalline silicon
Preparation Method Czochralski method cast polycrystalline method
Wafer size(mm) 100*100 100*100
125*125 150*150
150*150 210*210
Silicon resistivity(Ω·cm) 1~3 0.5~2
Wafer thickness(μm) 200~300 220~300
battery efficiency 15~17 14~16
Advantages High conversion efficiency, low impurity concentration and high quality High material utilization, low energy consumption, low cost and large size
Disadvantages High material waste, high energy consumption, high cost and small size Grain boundaries, grains, dislocations, micro-defects, high impurity concentration

2. Manufacturing Process

The processing flow of single-crystal silicon mainly includes truncation → rounding → square cutting → flat grinding → slicing → chamfering → grinding plate → chemical etching → polishing and other steps. In contrast, polysilicon does not have the steps of truncating and rounding and only needs to be cut into squares and sliced after the preparation of the ingot.

In the process of preparing monocrystalline silicon and polycrystalline silicon from ingots (ingots) to chips, diamond tools of different uses are required to participate in the processing, and the processing precision is relatively high. The specific steps, corresponding tools and indicators are shown in Table 2.

Machining Process Diamond Tools for Application Tool Indicators
Cutting Diamond Circular Saw Blade/Diamond Band Saw  the circular saw blade of Diameter 200~600mm or the electroplated band saw blade of 0.5~1mm thickness
Rolling Electroplated diamond wheel or sintered cup wheel diamond grinding wheel of Diameter 300~400mm and diamond particle size is 250#
Slice Diamond internal circular saw blade or diamond wire saw Electroplated inner circular saw blade with a thickness of about 0.3mm or a diamond wire saw with a wire diameter of 0.12~0.16mm
chamfer Diamond Grinding Wheel resin or metal bond grinding wheel with diamond partical size of 250#
Polishing Metal Bonded Diamond Grinding Wheels
Resin Bonded Diamond Grinding Wheels
2000# resin-based grinding wheel with diamond 2000# is used for rough polishing, and diamond grinding wheel with diamond 8000# is used for fine polishing
CMP chemical mechanical polishing Diamond Dresser Diamond electroplating, high temperature brazing, PCD dresser
Backside Thinning grinding  Metal Bonded Diamond Grinding Wheels
Resin Bonded Diamond Grinding Wheels
Diameter 150~250mm, diamond grain size 400#, bowl-shaped diamond thinning grinding wheel
Dicing Diamond ultra-thin cutting disc Electroplating cutting blade with thickness of 0.15~0.1mm or hot pressing sintering cutting disc with thickness of 0.1~0.5mm

2.1  Wire-electrode Cutting

After the single crystal silicon ingot is pulled out, the head and tail are removed according to certain requirements, and after cutting to a certain length and processing the outer circle, the single crystal silicon rod must be cut into wafers of a certain thickness. The tools used were diamond internal circular cutting discs in the early days, and their cutting surfaces were flat and fine, but the production capacity was limited due to the slow speed. In order to increase production capacity, diamond saw blades and diamond wires are currently used instead of diamond cutting blades.

There are two principles of wire cutting, one is reciprocating swing cutting, and the other is one-way continuous cutting. In the reciprocating wire cutting, the metal wire and the workpiece are in an approximate point contact state, and the cutting is performed in an arc shape.

The one-way continuous wire cutting process can be free grinding, using stainless steel wire or molybdenum wire with a diameter of 0.15~0.3mm, and adding Sic or diamond micro powder to the cutting fluid. It can also be a fixed-abrasive grinding process, and 0.15-0.5mm plated diamond abrasive wire is used for cutting.

Diamond Cutting Wire(mm) Diamond Particle Size (μm) Slit Size(mm)
0.127 20 0.140
0.203 45 0.229
0.254 60 0.279
0.305 80 0.330
0.381 100 0.419
0.508 120 0.546

2.2 Wafer Chamfers and Rounded Edges

The outer edge of the wafer cut by the wire cutting or inner circular cutting saw blade is very sharp. In order to avoid the edge cracking affecting the wafer strength, destroying the surface smoothness and causing pollution to the subsequent process, It must be automatically trimmed the edge, shape and outer diameter of the wafer with special CNC equipment.

Monocrystalline silicon grinding surface and polycrystalline silicon grinding surface chamfering also need a lot of diamond grinding wheels. The processing process is divided into rough grinding and fine grinding. The diamond particle size is 120/140, W40, W28, W20, etc., and the main size specifications are 6A2-220* 65*130*5*5, 6A2 200*60*80*5*5, 11A2-100*28(40)*31.75(20)*5*5, etc.

Diamond Grinding wheel for chamfer

             Diamond Grinding wheel for chamfer

2.3 Wafer backside thinning

The backside thinning grinding of wafers is divided into rough grinding and fine grinding. Coarse-grained diamond is used for coarse grinding, and fine-grained diamond is used for fine grinding.

Grinding wheel for Edging

                      Grinding wheel for Edging

Process Diameter Width High Diamond Size Matrix
Coarse Grinding  Φ204 2-5 5






Elastomeric resin bond matrix
Lubricating resin bond matrix
Non-porous ceramic bond matrix
Microporous ceramic bond matrix
Fine Grinding  Φ204 2-5 5 1000#~3000# Wear-resistant resin bond matrix
Sharp resin bond matrix

2.3.1 Application Characteristics

Thinning diamond grinding wheels usually include vitrified bond and resin bond, which are mainly used for the thinning and grinding of the backside or front side of the wafer in the manufacturing process of integrated circuits and discrete devices. The vitrified bond grinding wheel is mainly used for rough grinding. Resin bond grinding wheel is used for semi-finishing and finishing.

(1) Ultra-precision: The 2000# diamond grinding wheel with diamond powder 2000# is used to process an 8-inch silicon wafer, and the surface roughness Ra reaches 8nm. The diamond grinding wheel made of a special resin bond has surface roughness Ra≤2nm; parallelism (TTV)≤0.005mm; curvature≤0.5mm.

(2) High efficiency: the feed rate of the fine grinding wheel reaches 0.8m/s and 0.5μm/s (machine speed is 3600~4850rpm).

2.3.2 Product Characteristics

(1) Cup grinding wheel with diameter 114~444mm.

(2) The characteristics of the abrasive working layer: the narrow ring has a high thickness, the ring width is generally 2.5~3.5mm, and the thickness is 8~10mm.

(3) High requirements for manufacturing accuracy: dynamic balance accuracy≤G2.5; parallelism≤0.015mm; outer circle runout≤0.05mm;

(4) Ultra-fine particle size: 2000#(6~8μm), 3000#(4~5μm);

(5) According to the shape of the grinding wheel, it is divided into a whole cup shape, a shape with a water tank and a three oval shape with a water tank.

2.3.3 Key Technologies

(1) Low-temperature firing, high-performance vitrified bond suitable for diamond grinding wheels.

(2) Manufacturing technology of high porosity resin bond micro powder diamond grinding wheel.

2.4 Wafer Dicing

Wafer dicing requires the use of electroplating precision ultra-thin diamond saw blades, which are divided into two types in structure: one is an electroforming hub type cutting blade; the other is a circular hubless type cutting blade. This section briefly introduces the application characteristics, product characteristics and key technologies of electroplating bond for integrated circuit (IC) wafer dicing and high-precision ultra-thin diamond cutting wheels.

2.4.1 Application Characteristics

dicing blades, which are mainly used for micro-processing such as dicing, dividing or grooving of wafers in the pre- and post-processing of semiconductor integrated circuit (IC) and discrete (T°F) wafers. Its processing characteristics are as follows:

(1) Precision: the slit width error is less than ±5μm, and the slit collapse is less than 5μm.

(2) High speed: the operating speed is 30000~45000rpm.

2.4.2 Product characteristics

(1) Directly electroplating the diamond abrasive layer on the aluminium alloy substrate to form a hub-type cutting wheel.

(2) Ultra-thin: the thickness of the diamond abrasive powder working layer is 0.015~0.06mm.

(3) High precision: thickness accuracy is ±0.002~±0.004mm; hole (H) is 19.05+0.008+0.003mm; outer diameter is 55.60±0.05mm;

(4) Ultrafine diamond particle size: the smallest particle size is 0.5~2μm (30000#).

2.4.3 Key Technologies

(1) Uniform dispersion technology of ultra-fine powder abrasives.

(2) Electroplating solution formulation technology for low stress, high rigidity, high hardness and high flatness working layer.

(3) Technology to improve the bonding strength of coating and substrate.

(4) Precise removal technology of working layer supporting substrate after plating.

(5) Precision trimming technology for the outer circle and end face of the working layer.

(6) Non-contact detection technology of working layer thickness.

(7) Development of special equipment and devices, including high-efficiency precision electroplating devices and high-precision intelligent electroplating steady current power supplies.

2.5 Chemical Mechanical Polishing (CMP) Pad Dresser

Due to the development of ultra-large-scale integrated circuits (ULS) to highly integrated and multi-layer wiring structures, chemical mechanical polishing and planarization have become indispensable key processes for integrated circuits. It is not only the most efficient method to finally obtain a nanometer super smooth and damage-free surface in silicon wafer processing, but also an irreplaceable interlayer localized planarization method in the multilayer wiring of ULSI chips.The CMP process is used many times during wafer (chip) fabrication. At present, common dressers are (1) nickel electroplating type dressers, (2) high-temperature vacuum brazing dressers, (3) ceramic matrix ceramic bond dressers, (4) PCD dressers.

Taiwan KNIK company has developed a new type of PCD dresser. The PCD is sintered at 6GPa and 1350°C to form a trimmer carcass, which is then EDM machined into pyramids of specific size and shape. Pyramids arranged in a predetermined pattern are called ADD-Advanced Diamond Disks. Experiments show that ADD can make the polishing pad with high-density roughness, efficiently and uniformly polish the wafer, and double the lifetime (see Table 5).

DiaGrid ADD
Flatness of Diamond >50μm <20μm
Polishing Efficiency >50μm/h >20μm/h
Participate in the Work of Diamond Grains <10% >90%
Broken Diamond Grains >20% <1%
Diamond Shape irregular Uniform symmetry
Diamond Crystal Angle >1000 <900
Grinding Stress large (torn) small (cutting)
Polishing Temperature high low
Acid Proof Not acid-proof Acid proof
Pad Life short long
Dresser Life short long
Surface Roughness random uniform
Uniformity low high

3. Conclusion

Since the development of integrated circuits (IC) is inseparable from the basic material silicon wafers, more than 90% of the world’s IC use silicon wafers. Silicon crystal slicing is at the front end of the entire process flow and is an important process in chip manufacturing. It has an important impact on the processing quality and cost of the substrate, and the quality of the slicing will inevitably affect the processing of subsequent processes.

In the manufacturing process of silicon-based semiconductor devices, grinding wheel grinding is mainly used for two purposes. On the one hand, it can be used for fine grinding of etched silicon wafers. The amount of silicon wafers removed during the polishing process; another use is to reduce the overall thickness of the silicon wafers before the dicing process. With the growing demand in markets such as smart cards and smart labels, the demand for thin, flexible silicon chips is also increasing, thus requiring more back grinding processes.

As the “teeth of industry”, diamond grinding wheel increasingly reflects its excellent performance in many emerging industrial material processing fields. With the improvement of raw material performance, serialization of product specifications, specialization of production equipment and standardization of testing methods, diamond tools will develop towards a higher level, and product quality will be significantly improved.

1. Sapphire Processing Process

1.1 Sapphire Substrate Wafer Process

From the sapphire ingot to the final substrate sapphire wafer, it mainly includes the following steps: crystal growth → crystal pulling → head and tail truncation → rolling grinding → crystal rod orientation → slicing → chamfering and edge grinding → rough and fine grinding → CMP polishing. Each step needs to be equipped with different diamond tools to complete, the main tools are drills, grinding wheels, wire saws and so on.

Crystal Growth: using a crystal growth furnace to grow large and high-quality single-crystal sapphire.
Crystal Pulling: using a sapphire drill (high-precision diamond nesting drill) to pull out the sapphire crystal rod from the sapphire crystal;
Roll Grinding: use a diamond grinding wheel which is a resin bond or metal bond diamond grinding wheel to flatten the crystallographic direction of the crystal rod and grind the outer diameter to obtain precise outer circle dimensional accuracy. But now the rough grinding is generally a metal bond diamond grinding wheel, and the fine grinding is a ceramic bond diamond grinding wheel, and there are also companies that use resin bond diamond grinding wheels for rough and fine grinding.
Orientation: accurately locating the position of the sapphire ingot on the slicer, which is convenient for precise slicing processing;
Slicing: Use a diamond wire saw to cut the sapphire ingot into thin wafers;
Chamfering and edging: the edge of the wafer is trimmed into an arc shape with a metal bond diamond grinding wheel to improve the mechanical strength of the edge of the wafer;
Grinding: remove the wafer dicing damage layer caused by slicing and improve the flatness of the wafer. Divided into rough grinding and fine grinding, the abrasive products involved mainly include diamond grinding disc, diamond grinding fluid, diamond backside thinning grinding wheel, etc.;
Polishing: Using CMP polishing liquid to improve the roughness of the wafer, so that the surface can reach the epitaxial level precision of the wafer.

1.2 Packaging process

The epitaxial and encapsulation process mainly includes the following steps: substrate wafer → epitaxial wafer → evaporation and etching → heat treatment → backside thinning → grinding and polishing → scribing test → Fixing Crystal → wire bonding → Lineup encapsulation → cutting → testing. The abrasive products mainly involved in this process are diamond ultra-thin diamond cutting discs, diamond backside thinning grinding wheels, diamond grinding fluids, diamond polishing fluids, etc.

2. The introduction of super abrasives used in sapphire processing

2.1 High Precision Diamond Grinding Wheel

Diamond grinding wheels are most widely used in the processing of hard and brittle materials such as sapphire and silicon wafers. Different types of diamond grinding wheels are used from the processing of crystal rods to the roughing of wafers and then to finishing. Four representative grinding wheels are introduced below, which are crystal rod rounding diamon grinding wheel (Fig. a), thinning grinding wheel (Fig. b), plane grinding diamond grinding wheel (Fig. c), and diamond polishing wheel (Fig. d). The diamond particle size ranges from 100 mesh to 8000 mesh and the carcass material includes metal bond, resin bond and vitrified bond.

crystal rod rounding diamond grinding wheel/plane grinding diamond grinding whee/thinning diamond grinding wheel /diamond polishing wheel

As mentioned above, the sapphire process also uses a large number of diamond grinding wheels. For example, the outer diameter grinding and crystallographic flat grinding mainly use resin bonded diamond grinding wheels. The rough grinding of diamond particle size is about 100 mesh, and the fine grinding of diamond grits size is about 200#. The resin bond has a certain elasticity, which plays a polishing role and the processed workpiece is of good quality. The chamfering grinding wheel is a metal bond diamond grinding wheel and the common size is 1FF1V/9 202*20*30*2.5. The metal base diamond grinding wheel has high toughness and strength, high groove precision, and long service life.

The rough grinding of the Sapphire window is processed by a ceramic bond diamond grinding disc (Fig. 1). Compared with the cast-iron disc processing method, it has the advantages of high processing efficiency, high precision, good grinding quality and long service life. In addition, products such as back-thinning grinding wheels (Fig. b) and diamond grinding fluids (Fig.2) are also widely used and have great market value.

ceramic bond diamond grinding discDiamond Polishing Suspensions

Fig.1                                                                                     Fig.2

2.2 Diamond Ultra-thin Cutting Disc

The ultra-thin cutting blade (Fig. 3) is composed of diamond and binder to form a ring-shaped flake with a thickness between 0.015 and 0.3 mm. It can be divided into the metal-bonded diamond blade and resin-bonded diamond blade. The thickness of the metal bond electroplating blade is 0.015mm to 0.1mm, and the thickness of the metal bond hot pressing blade and the resin bond blade is 0.1mm to 0.3mm. Ultra-thin cutting wafers are widely used in the electronics industry to cut or slot various hard and brittle materials, such as silicon, germanium, gallium phosphide, gallium arsenide, gallium arsenide phosphide, ferrite, lithium niobate, tantalic acid Lithium, piezoelectric ceramics, optical ceramics, glass. It has the characteristics of high cutting accuracy, narrow slits, long service life and it needs to be installed on special equipment with a single blade or multiple blades at the same time.

Diamond Ultra-thin Cutting Disc

2.3 High precision diamond core drill

The diamond core drill (Fig. 4) is mainly used for the processing of relatively expensive hard and brittle materials such as sapphire, which is mainly used for the processing of watch cases, optical glass, and LED substrates. And the precision of the drill is very high.

Machining sapphire crystal rod with high precision diamond core drill bit


The manufacturing technology of trepanning drill bits includes ultra-thin annular tool bit manufacturing technology, high-precision welding technology and drill follow-up grinding technology. The quality of the ultra-thin ring cutter head plays a decisive role in the final use performance of the product. This technology includes a series of production processes and operating standards such as uniform mixing, fine granulation, standardized hot pressing and sintering, and mold release. High-precision welding technology is a key step to ensure drill concentricity and welding strength, including welding surface treatment, welding concentric adjustment, and standardized welding. The follow-up grinding technology of the drill bit can further improve the accuracy of the drill bit.

2.4 CMP Dresser

With the rapid development of the semiconductor industry, the size of electronic devices is reduced, and the surface flatness of the wafer is required to reach the nanometer level. Traditional planarization techniques can only achieve local planarization, but when the minimum feature size is below 0.25 μm, global planarization must be performed. At present, the only technology that can achieve global planarization is mechanical chemical polishing (CMP), which is to use chemical etching and mechanical force to smooth substrate materials such as wafers during processing.

The working principle of CMP is to fix the wafer on the bottom, and then place the polishing pad on the grinding disc, and the abrasive fluid composed of sub-micron or nano-abrasive particles and chemical solution flows between the surface of the wafer and the polishing pad. During polishing, the rotating polishing head is pressed against the rotating polishing pad with a certain pressure to flatten the wafer. Polishing pads are consumables and are generally made of polyurethane material with porous materials. The surface of the polishing pad must be regularly trimmed with a diamond conditioner called CMP conditioner to improve its life. The purpose of the CMP conditioner is to sweep over the pad surface to improve surface roughness and remove spent diamond slurry. The conditioner contains a stainless steel disc and a nickel-plated (CVD diamond layer) diamond grit, which size is about20 μm. (Figure 5).


The polishing pad dresser is used for the topography modification of the polishing pad. The research on the dresser focuses on the size of the dresser, the size of the diamond particles, the density of the diamond particles, the arrangement method, the bonding method. The bonding method of diamond particles is the main research content, and it is required that while ensuring the life of the dresser, the diamond particles will not fall off, so as to avoid scratching the wafer.

There are many abrasive products used in the sapphire industry. Due to the high added value of sapphire workpieces, the corresponding diamond tools have high-performance requirements and must have good stability, which makes diamond tools more expensive and profitable.

Superabrasives have always been called “industrial teeth” in the field of industrial production, and are used in the manufacture, grinding, grinding and polishing of almost all industrial products. This article summarizes the important manufacturers and suppliers of Chinese superabrasives industry in detail,  so that everyone can have more understanding of the synthetic diamond powder and diamond tools industry.

Famous Superabrasives Manufacturer and Supplier in China


SINOMACH is composed of China Machinery Industry International Cooperation Co., Ltd., Zhengzhou Abrasives Grinding Research Institute Co., Ltd. and Baige Abrasives Co., Ltd. Its main business covers the bearing industry, abrasives industry. It has strong strength in the research and development, manufacturing, testing and testing of high-precision, high-reliability bearings, high-speed and high-efficiency superhard products and related parts and components, and occupies a leading position in China. The leading products are precision and special bearings, superhard tools, industrial equipment and testing instruments.


Beijing Antai Gangyan company is engaged in the research, development, manufacture and sales of diamond tools. The main products of ANTAI include laser welding saw blades, high frequency welding diamond saw blades, cold-pressed sintered diamond saw blades, hot-pressed sintered saw blades, diamond rhinestones, diamond grinding wheels, diamond wire saws, and diamond synthetic catalysts.


Founded in 1994, Bosun Company is headquartered in Shijiazhuang. It has 5 production bases and 8 wholly-owned subsidiaries, located in the United States, Canada, Thailand, South Korea, Changzhou and Shanghai in China. It has two business divisions, namely diamond tools business Department and Rail Transit Equipment Division.

Bosun Company currently has three major business segments: hardware tools (diamond tools, power tools and alloy tools), coated abrasives and rail transit equipment. Hardware tools are mainly used in construction, decoration, building materials processing and other fields. As an industrial “teeth” and “beautician”, coated abrasives play an important role in aerospace, shipbuilding, automobile manufacturing, metallurgy, rail transit, power generation equipment, strategic emerging industries, petrochemical textiles, energy materials and other downstream manufacturing industries. Rail transit equipment mainly refers to various equipment related to the operation of rail transit vehicles, which is a new business segment of the company. At present, high-speed train brake pads have been officially put into production.

4.  SF Diamond 

SF Diamond company is mainly engaged in the research, development, production and sales of composite superhard materials and superhard material products. It is one of the largest R&D and production enterprises of polycrystalline diamond (PCD). PCD, PCBN and polycrystalline diamond wire drawing die blanks can be widely used in petroleum, mining, wire drawing blanks and cutting tools.


Golden Sun has been focusing on paper-based and new substrate-based abrasive products, which belongs to the coated abrasives industry. Golden Sun’s products are widely used in aerospace, automobile manufacturing, steel, 3C electronics, furniture, musical instruments, textiles, leather and other industries, providing high-end products and personalized system solutions for customers’ precision grinding and polishing.


Founded in 1990, Crownkyn Superabrasive is a high-tech comprehensive enterprise engaged in the research, development, production and sales of superhard materials and superhard tools. The products mainly include synthetic diamond powder, nano-diamond, polycrystalline diamond powder, coated diamond powder, CBN powder and PCD tools, which is widely used in advanced manufacturing fields such as national defence, aerospace, equipment manufacturing, and electronic technology.

Crownkyn Supabrasive has a number of core key technologies and independent intellectual property rights, and the comprehensive indicators of some of its products have reached the international advanced level.


The main products of King Strong include metal-based superhard material products, metal-bond wear-resistant material products and electromagnetic functional materials, providing technology-leading products and services for ceramics, mining, construction, building materials, metallurgy, electric power, refractory materials and military industries. The company has established the “Guangdong Province Superhard and Electromagnetic Functional Materials Engineering Technology Research and Development Center”.


Worldia is a leading and world-class superabrasives supplier in China. Since its establishment in 2006, it has been mainly engaged in the research and development, production and sales of ultra-high precision and high-precision superhard tools and superhard material products. Wald’s main products can be divided into diamond cutter wheel products and cutting tool products according to different application fields. Advanced manufacturing fields such as high-precision cutting of core components such as gearboxes.


The main business of Sanchao Advanced Materials is the research and development, production and sales of diamond tools. The main products are electroplated diamond wire and diamond grinding wheel.


Dialine New Material is a high-tech enterprise specializing in diamond wire research and development, production, sales and service. It is also the first enterprise and leading diamond wire manufacturer in China to master the core technology of diamond wire and put it into large-scale production. The company is committed to becoming a world-class comprehensive service provider of hard and brittle materials processing consumables, providing professional tools and complete solutions for the cutting of hard and brittle materials such as crystalline silicon, sapphire, integrated circuit chips, window systems, optical lenses, precision ceramics and magnetic materials.


Zhongnan Jete Superabrasive is a leading enterprise in the superhard material industry, mainly engaged in superhard material products, the main products include synthetic diamond, cubic boron nitride, composite sheets, lab-grown diamonds, large-scale polycrystalline diamond, high-purity graphite, etc.

Zhongnan Diamond has a nationally recognized enterprise technology centre and a nationally recognized superhard material testing center. It is a leading enterprise in China’s superhard material industry and one of the main setters of industry standards.


Sino-Crystal Diamond company is a high-tech enterprise integrating professional research, production and sales of superabrasive products industry chain. After years of development and accumulation, the company has formed a product series covering graphite ore, synthetic diamond powder and raw auxiliary materials, large single-crystal diamond and accessories, micro-diamond wire, superhard abrasives (grinding wheels). The products as engineering materials and functional materials are widely used in various fields of the national economy and people’s livelihood such as national defense and military industry, aerospace, equipment manufacturing, electronic technology and clean energy.


Huanghe Whirlwind is one of the world’s synthetic diamond manufacturing bases and a leading enterprise in superhard materials and intelligent manufacturing. The main products of Huanghe Whirlwind are carbon-based new materials (industrial synthetic diamond powder, PCD, PDC, diamonds for jewelry, diamond wire saws, diamond micron powder, graphene), intelligent manufacturing, alloy powder. It has now developed into a large-scale enterprise integrating scientific research, production and trade.


Yicheng Energy Company is a new material, new energy, energy-saving and environmental protection-oriented enterprise, with independent intellectual property rights of electroplating diamond wire, lithium-ion battery anode material production process and the world’s advanced PERC high-efficiency monocrystalline silicon battery production line.


The main business of Luxin High-tech Company is the production and sales of abrasives, abrasive tools, abrasive cloth and sandpaper. The downstream customers are mainly enterprises in the military industry, auto parts processing, aerospace, and precision processing; the key investment areas of the venture capital business include information technology, energy-saving Environmental protection, new energy, new materials, biomedicine, high-end equipment manufacturing and other industries.


Far-East Abrasives Company mainly develops and produces ceramics, resin bond abrasives, coated abrasives, synthetic diamond and CBN abrasives, electroplated superhard products, diamond dressing rollers, diamond saw blades and drill bits, diamond abrasive paste and various special grinding wheels. Far-East Abrasives has become a modern abrasives industry base integrating bonded abrasives and coated abrasives.

Other Abrasives Manufacturers And Suppliers in China


Introduction of World Famous Abrasives Companies

1. Saint-Gobain Group

Saint-Gobain Group founded in France in 1665 has five main businesses: flat glass, glass packaging, high-performance materials (reinforced glass fibers, ceramic plastics, abrasives), building materials (piping systems, thermal insulation and sound insulation materials) and building materials distribution. The group has 11 businesses that rank first in the world (including abrasives), and its technology level and production and sales scale are world-leading in the same industry.

Saint-Gobain is a leader in the abrasives industry, with three leading brands including NORTON, WINTER and FLEXOVIT, and is the world’s largest manufacturer of abrasives products.

2. 3M 

3M is a world-renowned multinational enterprise with diversified products, involving multinational groups in many fields such as home office, medical supplies, commercial cleaning, security protection, and electronic communications. 3M abrasive products mainly include coated abrasive products, non-woven abrasive products, ultra-fine abrasive products, abrasive tool products, and consolidated abrasive products.

Famous Superabrasives Companies in Other Countries


England: ElEMENT SIX


Austria: TYROLIT




India: CUMI

Finland: MIRKA


According to the characteristics and processing requirements of hard and brittle materials, the round micron diamond powder was produced by a special shaping process to round and roughen the particles to ensure that each particle is perfectly round and regular without prominent edges and corners. The rough surface of diamond particles significantly enhances the holding force with the workpiece, and its rounded shape can effectively avoid problems such as the chipping and scratching of hard and brittle materials during processing.

round micron diamond powder for Precision machining

Product Features

Round or spherical diamond particles

Smooth particle edge without sharp corner

Suitable for precision grinding or polishing

Product Details

Micron Diamond Powder for the Semiconductor industry is made of high-grade single-crystal artificial diamond as raw material. The diamond particles are almost spherical or round, with narrow particle size distribution, extremely low impurity content, good dispersibility and strong wear resistance, and can be combined with a variety of binders.

Spherical diamond polishing powderSpherical diamond polishing powder

Product Application

Round micron diamond powder is especially suitable for precision polishing of optical products, and silicon wafers. It also can be used to be made precision grinding wheels for polishing sapphire and jade, and it is also suitable for precision grinding and polishing of machinery, ceramics, gemstones, semiconductors and other materials. In addition, it also can be used to prepare various diamond tools such as metal bond diamond tools and electroplated diamond products, which provides the best solution for precision grinding and polishing in many fields.

precision grinding and polishing for semiconductor


Abstract: The bond strength of binder and diamond grits in metal-based diamond tools, the state of diamond cutting edge, and the performance and life of diamond tools have important influences. The bond strength between the bond and the diamond grits in the metal-based diamond tool has an important influence on the state of the diamond cutting edge, and the performance and the life of the diamond tool. In this paper, the action mechanism and interface characteristics of carbide-forming elements and rare earth elements in multi-layer and single-layer metal-based diamond tools on the interface between bond and diamond are reviewed.

With the rapid development of the modern manufacturing industry, especially the development of electronic information, aerospace, new materials and other industries, a large number of high-performance diamond tools are needed for cutting, grinding and polishing semiconductors, functional ceramics, high temperature alloys, magnetic materials, optical crystals and other advanced hard and brittle materials. At present, diamond tools can be mainly divided into three types: metal-based, resin-based and ceramic-based according to the properties of the binder.

Due to the excellent matching of metal strength, hardness and toughness, metal-bond diamond tools have become widely used tools for processing hard and brittle materials. Since the interface bonding state between diamond powder and metal bond directly affects the bonding strength of diamond particles, the height of the cutting edge, and the processing efficiency, precision, and life of the tool, the research on the interface between diamond and metal bond is of great importance. This paper discusses the structure of the interface between industrial diamond powder and bond in multilayer and single-layer metal-based diamond tools, respectively.

1. The interface between diamond and binder in multilayer diamond tools

Multilayer diamond tools are usually densified by sintering synthetic diamond grits and metal binder mixture powder, so they are also called sintered diamond tools. At present, the binder of sintered diamond tool is mainly Co-based, Cu-based and Fe-based. Co is the best binder to the bond diamonds at present. The cu-based binder is usually based on Cu-S alloy, which is widely used as a binder due to its low melting point and good sintering performance. The appearance of the Fe-based bond is a new bond proposed to reduce the cost of Co and Cu. Because Fe and diamond powder can react to form carbides, Fe-based bond has strong bond strength to diamond. However, due to the strong etching effect of Fe on the surface of diamond particles, the strength of diamond itself will be reduced. In addition, Fe powder is easy to oxidize, when the sintering temperature is high, not easy to edge, and needs to add a certain amount of other alloy elements, such as Co, Ni and so on. Therefore, Fe – based binders are not widely used.

In order to improve the bonding state between the metal bond and the diamond, on the one hand, the diamond can be coated or directly add a small amount of other elements (such as carbide forming elements, rare earth elements, etc.), on the other hand, On the other hand, a layer of carbides forming elements with affinity to diamond is coated on the diamond surface to make diamond have the characteristics of metal.

The layer of carbide-forming elements that have an affinity for diamond gives the diamond its metallic character.

Vaccum Brazed Diamond Grinding Head for Stone

1.1  Interface effects of carbide-forming elements in binders


Adding carbide forming elements such as Ti, Cr, V, Mo, W and Zr into the bond of sintered diamond tools can obviously reduce the wettability Angle of the bond on the diamond. When Ti, Cr, V and other elements are added into Cu, the wettability Angle of the diamond decreases from 145° to 50° or even 0°. It not only improves the bonding strength of the binder to diamond grains but also improves the hardness and bending strength of the matrix.

1.2 Interaction of rare earth elements in binders at interfaces

Rare earth elements can be called industrial vitamins and can be added in small amounts to purify the grain boundary impurities of most materials, thus strengthening them. For sintered diamond tools, there are pollution from oxygen in the air and the surrounding environment in the process of gold treatment. Therefore, the main role of rare earth element is to purify and strengthen the grain boundary of the bond agent, and also to improve the bond state between the bond agent and diamond polishing powder.

1.3 The role of carbide-forming elements on the interface of diamond surface coating

Another form of addition of carbide-forming elements to sintered diamond tools is to pre-coat the diamond surface. Coating metal or alloy on the diamond grits surface can further improve the wettability of the bond to diamond, especially coating carbide-forming elements such as Ti, Cr, V, W, Mo, etc.

2. The interface between diamond and binder in single-layer diamond tools

Single-layer diamond tools have the characteristics of high cutting edge and do not need to be trimmed, and their sharpness and cutting efficiency are much better than multi-layer diamond tools, so they have been widely used in the field of processing hard and brittle materials. At present, the manufacturing methods of single-layer diamond tools mainly include electroplating method and brazing method.

Sintered diamond tool

2.1 Interface of electroplated monolayer diamond tools

Electroplating diamond tools is based on the principle of electroplating Ni deposition on the steel substrate and diamond surface, and the diamond is wrapped, so the Ni coating and diamond grit is just a simple mechanical inlay, some diamond and Ni coating gap will appear. Therefore, the interface bonding force between electroplated diamond and binder is very weak. Of course, other methods can also be used to improve the combination of electroplated diamond and Ni coating, such as the use of laser surface treatment, so that the local coating melting can also form a certain metallurgical combination with diamond.

SEM photo of the bonding state of electroplated metal and diamond

(SEM photo of the bonding state of electroplated metal and diamond)

2.2 Brazing interface of monolayer diamond tool

The brazing single-layer diamond tool is to melt the solder alloy at high temperature, fill the gap between diamond and steel matrix by capillary action, and pile up the diamond root to a certain height, the edge height is very high, can reach more than 70% of diamond abrasive diameter. The commonly used filler metals for brazing diamond mainly include Ag-Cu, Cu-Sn and Ni-Cr alloys. The interface bonding state and micro-structure characteristics of the bond and diamond in metal bond diamond tools have important effects on the bond strength, edge performance and life of the diamond, so it is very important to study the interface between the bond and diamond.

At present, the research on the interaction mechanism of carbide-forming elements, rare earths in the binder and diamond at the interface is not enough, especially the lack of in-depth microstructure analysis. Therefore, it is necessary to use various advanced analysis methods, such as transmission electron microscopy, Raman spectroscopy, X-ray diffraction, Auger energy spectroscopy to analyze and test the microstructure, microdomain composition, phase structure. It provides a strong scientific basis for improving the composition and preparation method of the binder and improving the final processing performance and life of the Metal bond diamond tool.

Superabrasive grinding wheels made of diamond powder or cubic boron nitride (CBN) have been widely used in various aspects of the grinding field because of their excellent grinding performance. The diamond grinding wheel is a high-performance tool for grinding hard alloy, glass, ceramics, gems and other high-hard and brittle materials. In recent years, with the rapid development of high-speed grinding and ultra-precision grinding technology, higher requirements have been placed on diamond grinding wheels. Ceramic and resin bonded diamond grinding wheels can no longer meet the needs of production. Metal bond diamond grinding wheels have been widely used in production due to their remarkable characteristics such as high bonding strength, good formability and long service life.

According to the different metal elements and alloy composition of metal binding agent, it can be divided into copper base, cobalt base, iron base, titanium base and so on. Transitional elements are the most widely used metal binder types.

Copper-Base Binder in Diamond Tools

The copper-based binder with Cu as the main component is the earliest researched binder type, which has the characteristics of good toughness, moderate strength and low sintering temperature. The research shows that in the copper-based binder, the two factors that determine the self-sharpening of the abrasive tool are the addition of alloying elements to improve the mechanical properties of the matrix and the interface bonding between Cu and diamond.

Commonly used copper-based binders include Cu-Fe-Co, Cu-Sn, Cu-Sn-Ti, Cu-Sn-Pb, Cu-Al-Mg and other systems.

Due to the characteristics of the electronic structure of the copper atoms, the bond strength of the copper-based bond and diamond cannot reach a very high degree. However, the emergence of cobalt-based binders made up for the lack of copper-based binders that do not hold diamond grains firmly.

Cobalt-Based Binder in Diamond Tools

Cobalt-based binders are widely used in sintered diamond abrasive tools. Cobalt-based binders have the characteristics of high hardness, good strength toughness, good chemical compatibility, low sintering temperature, and excellent wear performance. In cobalt-containing metal bond diamond abrasive tools, cobalt plays a very important role. It can moderately reduce the wear resistance of the bonding agent, so that the diamond grits can maintain a large edge height and ensure the sharpness of the abrasive tool. Usually, cobalt-based binders are mainly used in the fields of geology, rock drill bits and other fields that require high performance of abrasive tools. However, since cobalt is expensive and toxic, it is not suitable as the main component of metal binders from the perspective of cost-saving and environmental protection. Therefore, many engineers are currently working on the preparation of high-performance low-cobalt or even cobalt-free bond abrasives.

Iron-Based Binder in Dimond Tools

Iron-based binders are a potential alternative to cobalt-based binders. There are many types of iron powder used in iron-based binders, including reduced iron powder with simple production process and carbonyl iron powder mostly used in the manufacture of high-performance abrasives. The formation of iron alloys with other metals can greatly improve the performance of the carcass, even comparable to cobalt-based binders. Commonly used iron-based binder systems include Fe-Cu-Sn, Fe-Co-Ni, etc. The performance of iron-based binder is sensitive to the sintering temperature, which can easily cause under-burning or over-burning and erode diamond particles.

Due to the relatively large solubility of Cu in austenite, iron is easy to etch diamond grits during sintering, resulting in the influence of the sintering process on the performance of the binder matrix and many other factors that limit the application of iron-based binders.

Metal binder in diamond tools have excellent performance and wide application prospects, Crownky Superabrasive provides quality assurance and customizable synthetic diamond powder for metal bond diamond tools.


I.Cultivation method of Lab-Grown Diamond

Lab-grown diamond refers to the appearance, chemical composition and crystal structure of natural diamond crystal made in a laboratory or factory through certain technology and process. It is a polycrystalline diamond polymerized from diamond crystals 10 to 30 nanometers in diameter. Synthetic diamond has a history of sixty or seventy years. With the continuous development of science and technology, there are not only diamond materials for industrial applications but also synthetic diamonds with gem characteristics.

There are two production processes for lab-grown diamonds: high pressure and high temperature method(HPHT)and chemical vapor deposition(CVD)method.

(1)High Pressure and High Temperature Method (HPHT)

As early as 1954, scientists came up with the idea to create the first diamond in a laboratory by simulating the environment in which natural diamonds grow in nature and by putting extremely high pressure and high temperature (HPHT)in a large machine. There are mainly three kinds of equipment to simulate the environment of natural diamond formation: Cubic Press (Cubic Press), two-section ball Press and Belt Press.

HPHT method is the original diamond cultivation method and is often used to change the color of diamonds, such as pink, blue and green. At present, pure carbon is melted at temperatures of 1300-1600 °C and pressures of 870,000 LBF/In2 and deposited on diamond crystals for cooling and precipitation. Due to the machine structure, size and growth process limitations, it is difficult to cultivate large diamonds by the HPHT method, so it is mostly used to produce a small lab-grown diamond. Most diamond colors can reach D~F colorless, except for a small part of the laboratory diamond has not overcome the technology will be below H color; Most of the clarity is VS~SI grade, the slower the growth rate, the higher the clarity, and vice versa.

(2) Chemical Vapor Deposition (CVD)

In 1960, in order to improve the disadvantages of HPHT production method, scientists invented Chemical Vapor Deposition (CVD). This method uses a diamond plate as the seed, puts it into a vacuum environment, removes all impurities, and warms the environment to 800-1200 ℃. Inject hot methane and hydrogen, and use microwaves to release the carbon atoms in the methane. This carbon will slowly deposit on the diamond seeds, replicating the structure of the seeds and slowly growing. The color of CVD cultured diamond is mainly F~H, and the cleaner the impurities are removed in vacuum, the better the color. In terms of clarity, most of CVD diamonds exceed HPHT diamonds, generally between VVS~VS.

The diamond that laboratory cultivates comes to call rough diamond, a rough diamond looks humble, must pass careful cutting and grind process, just can become the diamond that we see flashing and brightness.

 III. Screening of Lab-grown Diamond

Sorting lab-grown rough diamonds into various categories requires skilled and trained sorters. They evaluate each diamond for its characteristics and sort them into different types, color, clarity, carats and shape.

VI. The marking for Diamond

Diamond lineation is marking the surface of a diamond. This is the first step in diamond cutting, which involves examining rough diamond and marking the surface of the diamond by experienced and skilled workers. The ultimate goal is to produce the largest, cleanest, most perfect diamond to represent the value of a diamond as high as possible.

Scribers need to maintain the original weight as much as possible while minimizing inclusions. The scriber uses a magnifying glass to study the structure of the diamond blank, which can take months for large diamonds and minutes for an ordinary rough diamond. No matter how small the diamond, each diamond needs to be examined carefully to make the right judgment. The scriber marks the diamond blank with Indian ink to indicate that the diamond is to be divided along this line. When drawing lines, draw lines in the direction of the diamond grain as far as possible.

V. The Cutting of Diamond

The cutting methods for diamonds include splitting and sawing.

(1) Splitting: the splitting worker will delimit the diamond line on the set fixed, and then use another diamond along the cutting line to cut a notch, and then put the square edge cutter on the notch, with a hammer on the cleaver with the appropriate force percussion, the diamond will be split into two or more pieces along the texture direction.

(2) Sawing: most diamonds are not suitable for splitting, then need to use sawing processing. Because of the high hardness of diamond, only diamond can cut diamond, so the saw blade is a round plate coated with diamond powder and lubricant on the edge. The diamond powder produced by Henan Crownkyn Company for diamond cutting has the characteristics of uniform particle size distribution, high hardness and strong wear resistance. The diamond is fixed on the clamp and the saw plate rotates at high speed to cut the diamond.

The introduction of modern laser technology into diamond cutting has greatly improved the machining efficiency of drill blanks. Now, Laser cutting technology is also the most common way of diamond cutting. Laser cutting will generate a lot of heat, need to keep water cooling. The advantage of laser cutting is that the cutting surface is very flat, and the consumption is very small.

During laser processing, the high temperature generated by the laser changes the structure of diamond carbon into graphite, making the diamond surface black after cutting, and the black surface can be polished off by diamond powder.

 IV. The shaping of a diamond by grinding

The sawed or split diamonds are sent to be rounded and shaped, and the diamonds are made into round, heart, oval, tip, emerald and other common cut flower shapes or other special shapes according to the design requirements. Since diamonds are by far the hardest natural substance known to man, only diamonds can polish diamonds. The diamond powder produced by Henan Crownkyn Company for diamond grinding has the characteristics of regular crystal shape, concentrated particle size distribution, extremely low impurity content, good thermal stability and high wear resistance.

Diamond polishing should rely on experience to grasp the basic shape of diamond, there are tripartite, octahedron, dodecahedron and crystal characteristics. The general method is to fix the diamond blank on the high-speed rotating lathe, and then use the diamond on the other arm to round the rotating rough diamond. When grinding, pick up the diamond every time to check the cut surface, and repeatedly check the degree of the cut surface.

With the development of technology, diamond design and cutting has been largely done by more accurate computers, but the last step of the polishing process can only be carried out manually and cannot be replaced by machines. A factory with nearly 100 employees can only finish more than 200 small diamond products in a busy day. If the diamonds are larger, the efficiency will be reduced to half.

The specific polishing process involves grinding all the facets on a cast-iron disc coated with diamond powder and lubricating oil to give the diamond an attractive glow. The process of grinding is usually to first make 8 large surfaces in the bottom layer and then make 16 facets. Add tip bottom, a total of 25 facets, and from this extension triangle facet, kite and waist facet, a total of 33 facets, so that a round diamond has 58 facets, if there is no tip facet, a total of 57 facets.

Not every diamond blank must go through all the above procedures, it must be based on the characteristics of the rough diamond itself and the goal to achieve. But any rough diamond, there are two processes are essential, is “marking” and “polishing flap”.

The position and angle of the surface produced by a carefully cut diamond are precisely calculated to give the diamond its maximum brilliance. The Angle at which a diamond is cut has a direct effect on the refraction and reflection of light.

Ⅶ. The Presentation of Diamonds

The lab-grown diamonds from crystal seeds to bright diamonds, not only need advanced equipment, more need to have rich experience, high degree of responsibility and concentration of the cutting division, in order to release all the brilliance of the diamond.

A diamond in a jewelry counter may have passed through many countries, through processing, setting, production before becoming a piece of diamond jewelry. With the progress of science and technology, the introduction of laser technology and electronic computer technology can make the design, cutting and grinding of the lab-grown diamond more accurate.

(World’s Largest Square Emerald Diamond Cutting)

Generally, powdery materials with a particle size of fewer than 54 microns are called micro powder, and those with a particle diameter of fewer than 5 microns are called fine powders. The particles larger than 3.5 microns were separated by the sedimentation method, and the mixture smaller than 3.5 microns was separated by a centrifugal method.

I. The Main Application of Diamond Powder

Diamond micron powder is mainly used for fine grinding, grinding, and polishing of non-metallic hard and brittle materials. Generally, 0~0.5 microns to 6~12 microns are used for polishing, 5~10 microns to 12~22 microns are used for grinding, 20~30 microns are used for fine grinding. Diamond micron powder is mainly used in the following four aspects:

  • Diamond powder is made into diamond grinding pastes, which is widely used in processing precision parts such as cutting tools, measuring tools, optical instruments, electronic devices made of materials such as hard alloy, high aluminum ceramics, optical glass, instrument gems, semiconductors and its processing roughness can achieve the mirror effect.
  • Diamond powder is widely used in the manufacture of fine grinding pieces, ultra-fine grinding pieces, electroplating products
  • Diamond powder is the main raw material to manufacture polycrystalline diamond products, such as geology, petroleum drill, cutting tools, drawing die, etc.
  • Diamond powder is used in the manufacture of abrasives and polishing fluids.

Ⅱ. Quality inspection of diamond powder

Diamond micron powder is mainly used for grinding and polishing, and the control of particle size is particularly important. If there are oversized coarse particles, the workpiece will be scratched, and the work of the previous process will be wasted. Therefore, the quality inspection of diamond micro powder is an important link to ensure the quality of micro powder products. Only by taking it seriously can we produce high-quality micro powder to meet the needs of users.

The quality inspection of diamond micro powder mainly includes size range, particle size distribution, particle shape, impurity content, marking and packaging. The main particle sizes are M0/0.25 M0/0.5 M0/1 M0.5/1 M1/2 M2/4 M3/6 M4/8 M5/10 M6/12 M8/12 M8/16 M10/20 M15/25 M20/ 30 M25/35 M30/40 M35/55 M40/60 M50/70. Particle size ranges for special applications are negotiated between supplier and purchaser.


The following table is the size range of M0.5/1:

Particle Size Nominal Size Range μm D5(Min.) μm D50 μm D95(Max.) μm The Largest Particles μm
M0.5/1 0.5~1 0.5 0.75±0.15 1.0 3.0

D50 refers to the particle size of a sample when the cumulative percentage of particle size distribution reaches 50%. Its physical meaning is that the number of particles with a particle size larger than it accounts for 50%, and the number of particles smaller than it also accounts for 50%. D50 is also called the median diameter or median particle size, and it is often used to represent the average particle size of the diamond powder.

Ⅲ. Particle size detection of diamond powder

In production practice, the laser diffraction method is mainly used to measure the diameter of diamond powder particles. The commonly used instruments are The British Malwan Mastersizer 2000 laser particle size analyzer, the American Microtrac company S3500 series laser particle size analyzer and the X100 laser particle size analysis instrument.

The advantages of the laser particle size analyzer are that it is convenient and fast to measure the particle size distribution curve and concentration degree of samples. The more spherical particles, the more accurate the measurement, widely used in the diamond industry. The disadvantage of this method is that it cannot accurately measure irregular shape and strip particles, so its numerical measurement is low. This may be related to its measurement principle. In software measurement and calculation, irregular shape and long strip particles are converted into sphericity, and then the diameter of the sphere is calculated as the particle size, so the measurement data is low. In order to overcome this shortcoming, in the production practice, the image method and biological microscope method are used for inspection, mainly to check the large particles and long particles, and the combination of laser particle size analyzer and microscope is used to ensure the quality of the micro powder.

The following figure is the report of the laser particle size analyzer of M0.5/1.5 micron powder. The particle size distribution of the micro powder is concentrated and the particles are uniform.

Ⅳ. Particle Size Testing of DiamondPowder

There are many kinds of instruments that can be used to measure the particle size of fine diamond powder, such as a biological microscope, projection microscope, image analyzer, projective electron microscope, scanning electron microscope, Kurt particle size analyzer, etc. Choose appropriate magnification when using the biological microscope to observe microparticles. When observing 1.5 micron fine powder, magnification 1500 times or 2000 times observation, the effect is better. Microscopic observation of microscopic particles to 0.25 micron and particles smaller than 0.25 micron can be observed by scanning electron microscopy.

Ⅴ. Detection of Particle Size Distribution of Diamond Powder

The particle size distribution has a certain effect on the cutting efficiency and grinding roughness of materials. For fine grinding and polishing process, it is required that the content of coarse particles and long particles should be less, the content of basic particle size should be high and the distribution should be concentrated, and the composition of particle size should be uniform. In particular, the micro powder used for electroplating products requires the micro powder to be of good height and uniform particle size composition, so that it is easier to control the edge height of the micro powder when electroplating, so as to achieve good use effect of products.

The following picture shows the image of diamond micro powder of good quality W1 under the biological microscope of 1500 times magnification, with uniform particle size distribution.

Ⅵ. Particle Shape Detection of Diamond Powder

In polishing, the particle shape of micro powder is the approximately spherical particle and regular shape is better. In the micropowder standard, needle-stick particles refer to needle-like or rod-like particles with the ratio of long axis to short axis exceeding 3:1. No needle rod particles larger than the maximum particle size are allowed in the micron powder, but the length of needle rod particles between the maximum nominal size and the maximum particle is allowed to exist, the content of not more than 3%.

Some of the diamond micro powders show transparent flake particles when observed under the microscope, and the size smaller than D5 can be excluded. Flake particles in diamond micron powders are not allowed to exceed 5%.

Ⅶ. Impurity Detection of Diamond Powder

The impurity content of diamond powder is not more than 2%, which usually contains metal impurities and non-metal impurities, mainly Including Si, Fe, Mn, Co, Ni, Ti, Ca, Mg, Na, etc. The quality of PDC diamond powder is relatively high, and the impurity content is controlled within about 50PPM.

The impurities in the micron powder were measured by the combustion weight loss method. 0.5 grams of micro powder was taken from the sample and put into a crucible of constant weight, placed in a muffle furnace, and burned at 1000 degrees to constant weight. The residual weight was the impurity mass, and the mass percentage calculated was the impurity content。

 Ⅷ. Cutting Force Measurement of Diamond Powder

Generally speaking, under the microscope, the flake powder has low strength, the block diamond powder cutting force is strong and has good quality. The coarse-grained powder is easy to judge, Good powder under the microscope, the core appears transparent and good transparency, surrounded by black edge outline. Low grade of the powder, the whole observation under the microscope is black.

Ultra-fine powder refers to the micro powder of 1.5 microns or less, which needs to be observed under an oil lens, the objective lens is immersed in cedar oil, and it can be observed under 1600 magnification. Conventional glycerin sample preparation, easy to agglomerate, observation effect is poor. The quality of ultrafine powder can be distinguished from imaging, which requires more practice and observation. Another advanced method is to use a German-made differential thermal analysis instrument to determine the initial oxidation temperature of the powder. But the high price of this instrument hinders its spread in industrial production.

In order to solve this problem, Henan Crownkyn Company through a lot of practice, found a new dispersant, successfully solved the dispersion problem. Oil immersion using a microscope, imaging clear.

During the inspection, Henan Crownkyn Company observed the fine powder by staining and judged the quality of the fine powder according to the color of the graph.

In order to better observe the image, avoid the displacement of micro powder in the dispersant, and take a clear image, Henan Crownkyn Company adopts adhesive film sample preparation, fixed micro powder, and take the image of real micro powder under the biological microscope.

Ⅸ. Conclusion

Synthetic diamond powder is mainly used in grinding and polishing processes, users often require the lowest diamond concentration and the fastest cutting speed, to obtain the best surface roughness and workpiece surface quality. In order to achieve such a high use effect, high-quality diamond micron powder is needed. The high-quality diamond powder should be controlled from the following aspects:

(1) Diamond strength: The strength of diamond raw materials should be high. The micro powder made of diamond produced by big manufacturers in Zhongnan Diamond Company and Huanghe Whirlwind Company as raw material has good quality, high wear resistance, and high cutting force. It is usually the micro powder made of yellow diamond powder in the market. The micro powder made of low-process diamond material produced by small manufacturers has relatively poor wear resistance and cutting force. It is usually that the micro powder made of green diamond powder. The micro powder of green diamond material is suitable for low-end resin bond products, which is usually exported to India at cheap prices. When polishing hard non-metallic materials such as crystal and zircon, high-quality diamond powder should be used. Resin bond diamond micron powder has no cutting force, cannot grind to the surface of the convex mark and the polishing effect is poor.

(2) The size and content of coarse particles: coarse particles should be controlled in the scope of national standards, the less the better. Larger than coarse particles is large particles, easy to cause scratching workpiece.

(3) Particle size distribution: the higher the concentration of particles, the better.

(4) Particle Shape: the application of fine powder with good roundness in polishing has a better effect; Diamond powder with low magnetic and high strength has a good effect in diamond electroplating wire saw. The general shape of micro powder, such as strip, block and flake, used in resin bond grinding wheel, is relatively sharp.