| 摘要 |
PURPOSE:To improve the electrical resistance and thermal conductivity of diamond by optimizing the amount of metals, the bonding degree of diamond particles, etc., in the synthesis of a polycrystalline diamond by the addition of a metal such as Co to diamond powder. CONSTITUTION:The polycrystalline diamond is composed of firmly bonded diamond particles having diameter of 1-50mum and contains particles of one or more kinds of metals selected from Co, Fe and Ni, having particle diameter smaller than that of the diamond particles and sporadically distributed between the diamond particles. The diamond has high insulation and thermal conductivity represented by a specific resistance of >=10MOMEGAcm and a thermal conductivity of >=500W/mK. It can be produced by dispersing raw material powder consisting of diamond powder or graphite powder having diameter of 1-50mum in a liquid and precipitating one or more metal chlorides selected from Co, Fe and Ni chlorides on the surface of the raw material powder particles. The product is heated in an H2-containing atmosphere at 600-1,000 deg.C to obtain a mixed powder containing 2-5vol.% of the above metal having diameter of <=0.1mum in the raw material powder and maintaining the powder at >=2,200 deg.C under a pressure of >=80,000atm. |
