NEWS
Artificial single crystal diamond is gradually developed after the 1950s, it is graphite as raw material, adding catalyst, by high temperature and ultra-high pressure synthesis. Synthetic polycrystalline diamond (PCD) is a kind of polycrystalline material which polymerizes diamond micropowder by metal binder (such as Co, Ni, etc.). Synthetic polycrystalline diamond is a special powder metallurgy product. It uses some methods and means of conventional powder metallurgy for reference.
During the sintering process, due to the addition of additives, the PCD crystals formed a bond bridge with Co, Mo, W, WC and Ni as the main components, and the diamond was firmly embedded in the solid skeleton composed of the bond bridge. The role of metal binder is to hold diamond firmly and give full play to the cutting efficiency of diamond. In addition, because the grains are freely distributed in all directions, it is difficult for cracks to propagate from one grain to another, so that the strength and toughness of PCD have been greatly improved.
1. Ultra-high hardness and wear resistance: incomparable material hardness in nature reaches 10000HV, and wear resistance is nearly one hundred times that of carbide blades;
2. The hardness, wear resistance, microscopic strength, grinding difficulty and friction coefficient between anisotropic single crystal diamond crystal and crystal direction of different crystal surfaces are very different from each other. Therefore, when designing and manufacturing single crystal diamond tools, the crystal direction must be selected correctly, and the crystal orientation of diamond raw materials must be carried out. The choice of front and back cutting surfaces is an important problem in designing single crystal diamond cutting tools.
3. Low friction coefficient: the friction coefficient of PCD blade is lower than that of other blades when processing some non-ferrous materials, about half of the hard alloy, usually about 0.2.
4, PCD cutting edge is very sharp cutting edge blunt radius generally up to 0.1-0.5um. And natural single crystal diamond tools can be in the range of 0.002-0.005um. Therefore, natural diamond tools can be used for ultra-thin cutting and ultra-precision machining.
5. The thermal expansion coefficient of diamond is smaller than that of carbide, about 1/10 of that of high speed steel. Therefore, diamond tool will not produce large thermal deformation, that is, the change of tool size caused by cutting heat is very small, which is particularly important for precision and ultra-precision machining with high dimensional precision requirements.
