| 摘要 |
A polycrystalline diamond which has sufficient strength, hardness, and heat resistance and is dense and homogeneous. It is usable in working tools such as cutting bits, dressers, and dies and in digging bits. Also provided is a cutting tool employing the polycrystalline diamond at the cutting edge. The high-hardness polycrystalline diamond is a polycrystalline diamond which consists substantially of diamond obtained by direct conversion through sintering from a raw material composition containing a nondiamond carbon material under extra-high-pressure ultra-high-temperature conditions without the addition of a sintering aid or a catalyst. The polycrystalline diamond has a structure comprising a mixture of fine diamond crystal grains having a maximum grain diameter of 100 nm or smaller and an average grain diameter of 50 nm or smaller and coarse diamond crystal grains having a grain diameter of 50-10,000 nm and a platy or granular shape. |
