Classification and application of diamond powder

Diamond powder refers to diamond particles with a particle size of finer than 60 microns, including single crystal diamond powder and polycrystalline diamond powder. With the rapid development of nanotechnology, a new type of diamond powder has been independently developed from the two original types of diamond powder: nano diamond powder.

 

 

Single crystal diamond powder:
Single crystal diamond powder is produced by crushing and shaping artificial diamond single crystal abrasive particles using special process methods of superhard materials. Diamond powder has high hardness and good wear resistance, and can be widely used in cutting, grinding, drilling, polishing, etc. It is an ideal raw material for grinding and polishing high-hardness materials such as cemented carbide, ceramics, gemstones, optical glass, etc. Diamond powder products are tools and components made from diamond powder.

 

Polycrystalline diamond powder: Polycrystalline diamond powder is made from graphite using a unique directional blasting method. The shock wave of the directional blasting of high-explosive explosives accelerates the flying metal flakes and hits the graphite flakes, thereby converting graphite into polycrystalline diamond. Its structure is very similar to natural diamond, which is formed by unsaturated bonds and has good toughness.

 

Nano diamond powder:
Nanotechnology is a high-tech technology that emerged after the 1990s. Nano-scale diamond is composed of diamond particles with a size of nanometers, that is, one billionth of a meter. It is a new material synthesized by explosion technology in recent years. It not only has the inherent characteristics of diamond, but also has small size effect, large specific surface area effect, quantum size effect, etc., thus showing the characteristics of nanomaterials. This kind of diamond synthesized in the detonation wave has a cubic structure, a lattice constant of (0.3562+0.0003) nm, a crystal density of 3.1g/cm³, and a specific surface area of ​​300m²/g~390m²/g. After being treated with different chemical methods, a variety of different functional groups can be formed on the surface of diamond. This kind of diamond crystal has a high adsorption capacity.

 

Since the mid-1990s, due to the needs of the development of high-tech industrial technology and cutting-edge science and technology, the production of diamond micropowder has shown the following development trends:

 

1. The particle size classification is getting finer and the particle size range is getting narrower
Currently, many industrial technology departments require the use of diamond micropowders of 0 to 4um. As for diamond micropowders of 4um or finer, the American national standard ANSIB74.20-1981 formulated in 1981 stipulates that there are only 3 levels of diamond micropowders of 4um or finer: 0-1, 0-2, 2-4. The industry standard 1DA formulated in 1984 stipulates that there are 5 levels of diamond micropowders of 4um or finer: 0-1/2, 0-1, 0-2, 1-3, 2-4.

 

From the manufacturer's standard, the particle size of diamond micropowder is finer and the particle size range is narrower. Among them, the diamond powder standard formulated by G.E. Company in the United States is divided into 6 levels of 4um: 0-1/2, 0-1, 0-2, 1-2, 1-3, 2-4. In the diamond powder standard formulated by DeBeers, 4um is divided into 8 levels: 0-1/2, 0-1, 0-2, 1/2-1, 1/4-1/2, 1-2, 1/2-3, 2-4. By 1996, the diamond powder standard formulated by Kay Industrial Diamond Company in the United States divided 4um into 17 levels, and the particle size range was very narrow, which can be regarded as the most advanced level in the world.

 

2. Natural diamond powder continues to develop
Among industrial diamonds, the production of artificial diamonds accounts for about three-quarters or even more, but in some departments, artificial diamonds cannot completely replace natural diamonds. The SND diamond powder produced by DeBeers is the only natural diamond powder. It is characterized by very uniform particle shape and particle size, sharp cutting edges, and a minimum particle size of about 0 to 0.25um. The grinding paste prepared with this natural diamond powder is very effective for polishing and processing super-hard metallurgical samples.

 

3. Diamond powder with ultra-high grinding performance
The Institute has been vigorously researching and developing the application of artificial diamond powder grinding paste. According to them, the production efficiency of diamond grinding paste used in polishing high-precision parts is 1 to 2 times higher than that of grinding paste made of non-diamond abrasives, and the processing finish can be improved by one level.

 

Diamond grinding paste is widely used and is often used for fine grinding and polishing of some high-precision and high-surface finish components. For example, it is used for fine grinding or polishing of metallographic specimens, wire drawing dies, clocks and watches and other industrial gem bearings, die and die, gauges and block gauges, aircraft high-precision hydraulic transmission parts and internal combustion engine parts, precision instrument components, radar equipment, various transistors and gyroscope parts, etc. In addition, it is also used for grinding diamond, cemented carbide, glass, quartz, ceramic, ruby, sapphire, germanium, silicon and other hard and brittle material components, as well as polishing cast iron, steel, non-ferrous metals and alloy parts; fine grinding of titanium, tantalum, zirconium and other difficult-to-process rare metal parts, etc.

 

At present, a company has developed a kind of artificial diamond micropowder with ultra-high grinding performance, and its processing efficiency is much greater than that of natural diamond micropowder. It is very effective for processing polygonal diamonds; processing components such as silicon diodes and germanium diodes can achieve the highest level of mirror finish.

 

4. Diamond micropowder with strict particle size tolerance
The particle size tolerance of this diamond micropowder does not exceed ±1um. Taking the particle size grade of 2-4um as an example, its particle size distribution percentage is as follows:

 

2.4 to 2.6um 0.2%; 2.6 to 2.8um 3.3%; 2.8 to 3.0um 7.0%; 3.0 to 3.2um 9.4%; 3.2 to 3.4um 10.8%; 3.4 to 3.6um 40.5%; 3.6 to 3.8um 18.6%; 3.8 to 4.0um 8.7%; 4.0 to 4.2um 1.5%.

 

This diamond micropowder is used in critical industrial sectors and absolutely eliminates technical problems caused by oversized particles.

5. Diamond powder synthesized by explosion method

With the progress of industrial technology, ultra-high precision dimensional tolerances are increasingly required, such as processing industrial sapphire, ferrite or ceramic components, shaped diamond products, multiphase metallographic specimens and ultra-hard metal parts. Practice has proved that diamond powder synthesized by explosion method can achieve good technical and economic effects. This diamond powder is characterized by polycrystalline particles, which are similar to black diamond (Carbonado) in terms of microstructure and appearance. This rare natural polycrystalline diamond is black due to the trace elements and has high hardness.

 

Diamond powder synthesized by explosion method is synthesized by controlled explosion of high-energy explosives. At present, it has entered industrial-scale production internationally.

 

6. Development of special diamond powder

Different diamond powders have their own characteristics. There is a kind of single crystal diamond powder, which is a high-strength complete crystal in the shape of a cubic octahedron with a multi-edge cutting surface. It is not easy to peel off into useless (non-cutting) fine grains. It has extremely effective retention with metal binders and has high strength and resistance to crushing and cracking under high temperature conditions. Therefore, diamond products used for metal binders have sharp cutting effects and can obtain better surface finish.

 

Another type of diamond powder is characterized by brittleness. Its particle shape is irregular quasi-circular blocks, and the surface is rough and uneven. When the particles are subjected to stress, its brittleness causes the particles to break, thereby generating new sharp cutting points. This type of diamond powder is ideal for manufacturing resin bonded grinding wheels, etc., and has a gentle fine grinding and polishing effect.

 

Undoubtedly, diamond powder is an indispensable abrasive for the development of products towards high, precise and cutting-edge. Its application has a very broad prospect and its application field is constantly expanding. At present, industrially developed countries are investing a lot of money and manpower in the research of synthesizing new industrial-grade diamonds, which will open up new opportunities for the application of artificial diamonds in science, technology and industry.