纳米金刚石解团聚的一种新方法——石墨化-氧化法

用炸药爆炸法制备的纳米金刚石(ND)是由直径为4～6 nm的金刚石微晶粒组成，但这种纳米晶粒相互团聚，形成尺寸大得多的团聚体，至今尚未找到很有效的解团聚方法.该文提出了一种可用于这种纳米金刚石解团聚的新方法——石墨化－氧化法.将纳米金刚石粉在氮气中1 000 ℃加热1 h，这时纳米颗粒表面和界面上生成石墨层，再用在空气中450 ℃氧化的方法，将界面上的石墨层除去.将经过这样处理后的样品放入水中用超声波分散后，超过50％（质量百分数）的金刚石颗粒可以被分散到直径小于50 nm.可见这种方法对纳米金刚石的解团聚有一定的效果.但是同时也生成了一部分尺寸更大的团聚体，认为可能是生成了颗粒间的C-O-C键，需要进一步用适当的化学方法进行解离.对这一过程的机理进行了初步讨论.

A New Method for Deaggregation of Nanodiamond from Explosive Detonation--Graphitization-Oxidation Method

Nanodiamond (ND) prepared by explosive detonation has primary particles of 4 ～6 nm in diameter, but itundergoes severe aggregation in forming aggregates of hundreds of nm, even several μm in diameter. A new method forthe deaggregation of nanodiamond (ND) is developed and some preliminary results using this method are presented: NDis first graphitized in nitrogen at 1 000 ℃ during which thin graphite layers are formed on the surface of the diamondparticles and at the particle boundaries. The sample is then oxidized by air at 450 ℃ to remove the formed graphite lay-ers. After such treatment the sample is suspended in water by ultrasonics, and the particle size distributions were mea-sured by the laser scattering method. It has been found that the diameter of about 50% ( w ) of the ND particles can be re-duced to less than 50 nm, while such ultrafine particles are absent in the suspension of the untreated ND. It is suggestedthat the deaggregation is caused by the removal of the graphite layers formed at the particle boundaries in the stage ofoxidation. It is also found that after oxidation, some aggregates with larger diameters (1 000 ～ 2 000 nm) are formed,which can be explained by the formation of inter-particle ethereal bondings (C -O -C) during the oxidation by air.