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).

1．Properties 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 Nitride（CBN）

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 Nitride（PCBN）Tool

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.

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.

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.

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.

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”.

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.

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.

Process	Diameter	Width	High	Diamond Size	Matrix
Coarse Grinding	Φ204	2-5	5	200/230 230/270 270/325 325/400 400/500 500/600	Elastomeric resin bond matrix Lubricating resin bond matrix Non-porous ceramic bond matrix Microporous ceramic bond matrix
	Φ250
	Φ300
	Φ350
Fine Grinding	Φ204	2-5	5	1000#～3000#	Wear-resistant resin bond matrix Sharp resin bond matrix
	Φ250
	Φ300
	Φ350

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.

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

1.  SINOMACH

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.

2. BEIJING GANGYAN DIAMOND COMPANY

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.

3.  BOSUN

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.

5.  GOLDEN SUN ABRASIVES

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.

6.  CROWNKYN SUPERABRASIVE

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.

7. KING STRONG

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”.

8. WORLDIA

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.

9.  SANCHAO ADVANCED MATERIALS

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.

10.  DIALINE NEW MATERIAL

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.

11. ZHONGNAN JETE SUPERABRASIVES

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.

12. ZHENGZHOU SINO-CRYSTAL DIAMOND

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.

13. HUANGHE WHIRLWIND

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.

14. YICHENG NEW ENERGY

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.

15. LUXIN HIGH-TECH COMPANY

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.

16.  SUZHOU FAR-EAST ABRASIVES

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

FUNIK, MONTE-BIANCO, WANBANG LASER DIAMOND TOOLS, Z-LIONE, EXIN DIAMOND, HUIFENG DIAMOND, YALONG DIAMOND, METRON, SISA ABRASIVE, JINGRUI, WEIYING TOOL, GRISH, GUANYI ABRASIVE, CHANGRUN DIAMOND

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

Germany：VSMPFRED, WINTER, KLINGSPOR, AOKO, HERMES

England： ElEMENT SIX

Switzerland：WINTHERTHUR,  REISHOUR AG

Austria： TYROLIT

Italy： VINCENT, SAIT, BBL, ITEXA

Japan: NORITAKE, SHOWA DENKO, ASAHI DIAMOND, SUMITOMO, FUJIMI, SANKYO RIKAGAKU, YELP

Korea： KOREAN ABRASIVES, ILJIN, EHWA, SDC, SUN MIGHT, DEERFOS

India： CUMI

Finland: MIRKA

 

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.

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.

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)

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.

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)