Uses of diamond powder and its developing tendency

By | 19/07/2019

Whether natural or artificial diamond powder is a kind of super hard and fine abrasive in the world today. With the development of high and new technology, it is more and more widely used in various industrial sectors.

Before the mid-1960s, 70% of the natural diamonds used in industry in the Soviet Union were used to break them into diamond powder, diamond grinding paste and diamond tools. Since artificial diamond was put into industrial scale production, almost all of these natural diamond products have been replaced by artificial diamond. According to statistics, by the end of the 1960s, 95% of the diamond tools manufactured by the Soviet Union were synthetic diamonds, and only 5% were natural diamonds. By the 1990s, the annual production of synthetic diamonds in the former Soviet Union was about 100 million carats. Thus it can be seen that the rapid development of synthetic diamond in the former Soviet Union and the large amount of diamond powder are used.

Statistical data show that in the early 1980s, the industrial diamond consumed by the developed western countries was about 100 million carats, of which the consumption of diamond powder was close to 10%, that is to say, 10 million carats.

The grinding ability of diamond is 1.25 times larger than that of cubic boron nitride, 2.85-3.57 times larger than that of silicon carbide and 6.25-7.14 times larger than that of white corundum. Therefore, as a kind of super hard abrasive, diamond powder has extremely superior grinding ability, which has been paid more and more attention by industrial developed countries. The grinding ability of diamond powder includes grinding ability of workpiece and its wear resistance and crushing resistance, which depends on its microhardness, particle size, strength, particle shape, thermal stability and chemical stability.

Generally speaking, the application of diamond powder as abrasive has three main aspects:
(1) Precision grinding or polishing of various precision components in industry, science and medicine;
(2) Used in the manufacture of resin bonding tools, metal bonding tools and plating tools;
(3) As a fine abrasive, it is used in mould processing, gemstone polishing and gemstone bearing manufacturing.

Besides being used as abrasive material, diamond powder is also used as functional material. For example, its thermal and electrical properties are used. By mixing diamond powder into thermosetting resin polymer, cellulose, phenolic resin or ceramic sheet, a new material with high thermal conductivity and low thermal expansion can be made. A new type of sheet material with high thermal conductivity, low thermal expansion and light weight can be made by mixing diamond powder with metal sheets, such as nickel sheet or stainless steel sheet. In the electronic industry, it can be made into high-density and high-energy components for thermal control.

As far as the form of diamond used as abrasive material is concerned, according to the published figures, more than 60% of the diamond powder consumed in industry worldwide is used to make diamond abrasive paste, mixture of diamond powder and abrasive fluid of diamond powder.
With the development of high precision grinding technology, more precise tolerances can be obtained in geometric dimensions such as flatness, parallelism and flatness of parts. The main problem facing the grinding industry is that there are no fine scratches and other defects on the surface. How to eliminate these defects mainly depends on four factors:
(1) The uniformity of diamond powder size;
(2) Particle shape of diamond powder;
(3) Mixing ratio and purity;
(4) Carrier chemistry.

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 powder has shown the following trends:

1. The grain size classification is getting finer and finer, and the grain size range is getting narrower and narrower.

At present, many industrial and technical departments require the use of 0-4m diamond powder. As far as the fine diamond powder is concerned, the national standard ANSIB 74.20-1981, which was formulated in 1981, stipulates that the fine diamond powder with 4 meters has only three grades: 0-1, 0-2, 2-4. The industrial standard 1DA formulated in 1984 stipulates that diamond powder with fineness of 4m has five grades: 0-1/2, 0-1, 0-2, 1-3, 2-4. According to the manufacturer’s standard, the diamond powder has finer particle size and narrower particle size range. G.E. Company is the largest diamond powder manufacturer in the world. It is estimated that it produces 60% of the world market for diamond powder. DeBears, UK, accounts for 30%. In the standard of fine diamond powder formulated by G.E., 4m is divided into six grades: 0-1/2, 0-1, 0-2, 1-2, 1-3, 2-4. In the standard of diamond powder formulated by DeBeers, 4m is divided into 8 grades according to fineness: 0-1/2, 0-1, 0-2, 1/2-1, 1/4-1/2, 1-2, 1/2-3, 2-4. By 1996, the standard of diamond powder formulated by Kay Industrial Diamond Company of the United States divided 4m into 17 grades in fineness, and the range of grain size is very narrow, which can be called the most advanced level in the world.

2. Natural diamond powder continues to develop

Artificial diamond accounts for about three-quarters or more of the production of industrial diamond, but it can not completely replace natural diamond in some sectors at present. SND diamond powder produced by DeBeers Company is the only natural diamond powder. It has the characteristics of uniform particle shape and particle size, sharp cutting edges, and the smallest particle size is about 0-0.25m. The abrasive paste prepared with this natural diamond powder is very effective for polishing and processing superhard metallurgical samples.

According to Kay Industrial Diamond Company, its production of natural diamond powder has not declined for 50 years, because natural diamond powder has special physical and chemical properties, which are incomparable to synthetic diamond powder. The natural diamond powder produced by the company has 55 particle sizes, and the fineness of 4m is mostly in 13 particle sizes: 0-1/5, 0-1/4, 0-1/2, 0-1, 1/2-1, 1-1, 0-2, 1/5-3, 1-3, 1-3, 2-3, 2-4.
3. Diamond Powder with Ultra-high Ab

rasive Property
The former Soviet Union Superhard Materials Research Institute has been vigorously studying and developing the application of synthetic diamond powder abrasive paste. According to their opinions, the production efficiency of diamond abrasive paste used in polishing high precision parts is 1-2 times higher than that of non-diamond abrasive abrasive abrasive paste, and the polishing finish can be improved by one grade.

The diamond abrasive paste used in the former Soviet Union is widely used in the fine grinding and polishing of some high precision and high surface finish components. For example, it can be used for fine grinding or polishing of metallographic specimens, drawing dies, clocks and other industrial gem bearings, pressing and punching dies, 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 diamonds, cemented carbides, glass, quartz, ceramics, rubies, sapphires, germanium, silicon and other hard and brittle material components, as well as polishing of cast iron, steel, non-ferrous metals and alloy parts, and precision grinding of titanium, tantalum, zirconium and other difficult-to-process rare metal parts, etc.

At present, the former Soviet Union has developed a kind of artificial diamond powder with ultra-high abrasive properties, and its processing efficiency is much higher than that of natural diamond powder. It is very effective for processing polygonal diamonds, and can achieve the highest mirror finish for processing elements such as silicon and germanium diodes.

4 Diamond Powder with Strict Granularity Tolerance
The grain size tolerance of this kind of diamond powder does not exceed (+1 m). For example, the grain size distribution percentage of the diamond powder is as follows:
2.4 to 2.6 m 0.2%; 2.6 to 2.8 m 3.3%; 2.8 to 3.0 m 7.0%; 3.0 to 3.2 m 9.4%; 3.2 to 3.4 m 10.8%; 3.4 to 3.6 m 40.5%; 3.6 to 3.8 m 18.6%; 3.8 to 4.0 m 8.7%; 4.0 to 4.2 m 1.5%.

This kind of diamond powder is used in the vital industrial sector and absolutely eliminates the technical problems caused by super-sized particles.
5. Diamond powder synthesized by explosive method

With the development of industrial technology, ultra-high precision dimensional tolerances are increasingly required, such as sapphire, ferrite or ceramic components for processing industry, shaped diamond products, multiphase metallographic samples and superhard metal parts. Practice has proved that the diamond powder synthesized by explosion method can obtain good technical and economic results. This kind of diamond powder is characterized by polycrystalline particles. It is similar to Carbonado in microstructure and appearance. This rare natural polycrystalline diamond is black due to its trace elements and has high hardness.

Diamond powder synthesized by explosion method is synthesized by controlled explosion of high-energy explosive. At present, the world has begun to enter industrial scale production.

6. Developing Special Diamond Powder

Different diamond powders have their own characteristics. There is a kind of single crystal diamond powder with high strength and intact crystal, cubic octahedron shape, multi-edged cutting surface, which is not easy to peel into useless (no cutting ability) fine grains. It has a very effective retention force with metal binder. It has high strength and anti-fragmentation at high temperature. Because of its breaking ability, diamond products used as metal binders have a sharp cutting effect and can obtain a better surface.

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