Tungsten Carbide – Polycrystalline Diamond Buttons (2/2)

Foreign scholars also try to use as cubic boron nitride carbide substrate and the buffer layer between the polycrystalline diamond layer having a volume ratio of 1 (CBN): 4 (polycrystalline diamond). The coefficient of thermal expansion of CBN at high temperatures between polycrystalline diamond and tungsten carbide, which effectively reduces the thermal stresses between them, and this excellent compatibility also reduces thermal stress micro-cracks caused by greatly enhancing the impact toughness of the composite buttons. Domestic research agencies by reducing the synthesis of polycrystalline diamond binder content, while increasing the pressure and increase the baking time between making polycrystalline diamond particles are bonded D - D chemical bond is increased, thereby increasing tungsten carbide - polycrystalline diamond compact buttons impact resistance.

D – D is a kind of chemical bond, which has higher binding strength than the physical strength of binder and the higher binding strength, the better impacting resistance. In addition, added polycrystalline diamond sintering process nickel-based or titanium-based additive, which has good wettability of polycrystalline diamond particles, can cover around the polycrystalline diamond particles in the sintering process, prompting more polycrystalline diamond melting the particles more conducive D-D bond combination.

American scholars designed a double polycrystalline diamond composite sheet, the outermost layer of polycrystalline diamond using coarse particles, with high impact resistance; and the inner layer using fine diamond particles, effectively improve the wear resistance. The inner layer of diamond, cobalt Co incorporated as a sintering agent, the outer layer of the coarse grain diamonds contain less or no cobalt; during sintering process, cobalt (Co) by the formula sweep extended through the inner layer to the outer layer of the fine particles of rough diamond grain diamond layer. Due to fine-grained diamond layer as the substrate, it has uniform distribution in the process of sintering and avoids undersintering and softening caused by Co distributed unevenly.

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