高温高压下纳米金刚石粉的特性研究

 研究了炸药爆轰合成的纳米金刚石粉在高温（约1 600 K）、高压（5.2 GPa）条件下的行为。将纳米金刚石粉与粉末合金（Ni₇₀Mn₂₅Co₅、100^#）混合、压制成圆片，与合金片 （Ni₇₀Mn₂₅Co₅）和人造石墨片一起交替放入高温高压合成腔体内，进行高温高压实验。实验结果表明：在高温高压条件下，纳米金刚石粉不能长大，反而石墨化了；在相同的高压和保温时间条件下，随着温度的降低，纳米金刚石粉的石墨化程度减弱，纳米金刚石粉的纳米颗粒长大，可长成0.1 mm尺寸的金刚石颗粒（温度为1 070 K左右）。而在此条件下，人造石墨不能合成金刚石，一般金刚石晶体要变成石墨相。这进一步表明，纳米金刚石颗粒表面的活性使得它可以在较低的温度下长成较大颗粒的金刚石。

STUDY ON THE PROPERTY OF NANOMETRIC DIAMOND PARTICLES UNDER HIGH TEMPERATURE AND HIGH PRESSURE

Under high temperature (1 000～1 600 K) and high pressure (5.2 GPa) with Ni₇₀Mn₂₅Co₅ (100^#) being the catalyst, the growing behavior of nanometric diamond particles (2～10 nm) synthesized by the detonation of the explosives has been investigated. The effects of growing conditions on the microstructure and property of sintered nanometric diamond were studied. The samples compressed with nanometric diamond powder and Ni₇₀Mn₂₅Co₅ (100^#) alloy powder and the disks of Ni₇₀Mn₂₅Co₅ (100^#) alloy were put in the synthesis reaction cell on alternate. The results indicate that the nanometric diamond powder did not grow, but convert to graphite under high temperature and high pressure. Under the same high pressure and holding time, the degree of graphitization of nanometric diamond powders begin to decrease with the temperature decreasing, and nanometric diamond powders begin to grow. Diamond particles with the diameter of 0.1 mm can be acquired under high temperature (1 070 K) that the ordinary graphite doesn't convert to diamond and the ordinary diamond crystal will convert to graphite. This phenomenon shows that the nanometric diamond particles can grow into larger diamond particles under lower temperature because of the surface activity of nanometric particles.