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How to effectively improve the quality of PCD tools in China
How to effectively improve the quality of China (PCD) diamond tools.
1.High-strength diamonds with stable mass production, coarse particles and good thermal stability for diamond tool manufacturing
The grade quality, particle size and concentration of diamonds play a decisive role in diamond tools. In China's diamond synthesis, the six-sided top small tonnage high-strength process has matured, the six-face top large tonnage large cavity process has been continuously improved, and the two-sided top synthetic diamond has also begun to take shape. The powder catalyst synthesis, carbon, and pyrophyllite block raw materials are constantly being produced. perfect. Therefore, for the manufacture of diamond tools in China, high-strength diamond with stable performance, coarse particles and good thermal stability is possible. Foreign diamond companies, in addition to launching SDA+, SDB, DSN, MBS, ISD series, DeBeers launched BKI, BK30, BK60, BK70 diamonds for the Chinese market, South Korea's Rijin company launched six-sided synthetic SDS series diamonds, all worthy of China Learn from peers.
2.Uses strong carbide forming elements to increase diamond holding power
A key factor in improving the cutting efficiency and life of diamond saw blades is to increase the holding power of the carcass to the diamond. The carcass has a good grip on the diamond, the diamond does not fall off prematurely, and has a large protruding height, sharpness during cutting and high efficiency.
There are three ways to improve the holding power of diamond ultra-thin cutting blades：
(1)Improve mechanical holding power. This is because the metal powder shrinks during sintering, forming a compressive stress to hold the diamond. The compressive stress is generated due to the difference in thermal expansion coefficient between diamond and the carcass metal, which is caused by volume change caused by sintering or crystal formation and growth. Due to the limited yield strength of the carcass, the resulting compressive stress and mechanical holding force are limited.
(2)A small amount of strong carbide forming elements such as Cr, W, Mo, etc. are added to the powder. Due to its good wettability and affinity to diamond, carbides are formed at the interface between the diamond and the carcass metal during sintering to achieve a secondary gold bond to the diamond. It is conducive to strengthening and improving the holding power.
(3)The diamond surface is plated with a layer of strong carbides to form metal elements such as Cr, Ni, Ti, W, and the like. This is a process that has been adopted in recent years. To this end, Yanshan University has specially developed and produced three types of vacuum micro-evaporation titanium plating equipment.
According to experimental research and use at home and abroad, the effective conditions and scope of diamond plating technology are:
①Suitable for high grade diamonds, the effect is more obvious.
②The order of improvement of the holding force in the pure drill carcass is: Cr plating > Ti plating > unplated diamond.
③MBS-960Cr2 chrome diamond is suitable for Co-based carcass, low-iron low-bronze carcass and WC carcass.
④MBS-960Ti2 titanium-plated diamond is suitable for drilling bronze-based carcasses and iron-based carcasses.
⑤Tungsten-plated diamond is used in cutting asphalt, conservation concrete (GreenConcrete) and reinforced (reinforced steel) saw blades.
⑥Nickel-plated monolithic diamond ultra-thin cutting piece is suitable for resin bond grinding wheel, and its effect is as follows: needle-shaped nickel-plated diamond > nickel-plated diamond > unnickel-plated diamond.
⑦Silver-plated diamond is suitable for grinding precision resin bond grinding wheels for tungsten carbide carbide tools. Because the price of silver is not very expensive, it is suitable for high-precision grinding, and its thermal conductivity is good, suitable for oil-cooled grinding of hard alloys. At the same time, silver is a good lubricant, which can reduce the friction between the grinding wheel and the workpiece, and the heat is not large.
3.Ultrafine powder and prealloyed powder are used.
In the production of special saw blades, ultrafine metal powders and prealloyed powders should be used. The refinement of the metal powder is advantageous for lowering the sintering temperature and increasing the hardness. The use of pre-alloyed powder can prevent premature loss and segregation of low melting point metals, favor the elastic limit and yield strength of sintered products, increase the holding power of diamond, and reduce the sintering temperature and holding time. China Shanghai Materials Institute, Beijing Artificial Crystal Institute, Changsha Metallurgical Materials Institute and Zhongnan University of Technology Powder and Metallurgical Institute have done a lot of work in this regard. In the production of high-end saw blades, South Korea usually uses ultrafine powders and pre-alloyed powders from companies such as BASF, UM, INCO, Fum-tungstene, and Kennametal.