高温退火对Ⅱb型金刚石单晶热稳定性的影响

Influence on Thermal Stability of lib Type Diamond Single Crystals under High Temperature Annealing

在铁基触媒原材料中添加六方氮化硼,采用粉末冶金方法制备片状触媒,在六面顶压机上合成出Ⅱb型金刚石单晶。将所得Ⅱb型金刚石单晶分别在600℃,800℃及1100℃下保温60min进行退火处理。用差热分析仪对退火处理前、后的金刚石单晶分别进行差热分析和热重分析,从而将其在空气中的热稳定性进行对比。结果表明,Ⅱb型金刚石单晶的热稳定性经退火处理后可以明显改善,但是退火温度过高,Ⅱb型金刚石单晶的热稳定性又出现下降趋势,因此其退火温度存在一个最佳值。

The synthesizing experiments ofⅡb type diamond single crystals were carded out at six-anvil high-pressure apparatus with iron-based catalysts doped with hBN made by powder metallurgy method.The diamond crystals were annealed in inert gases for 60min at 600℃,800℃and 1100℃respectively.DTA and TG analysis were carried through on the diamonds before and after annealing by a thermal analysis system.And their thermal stability was compared in atmosphere at the same time.The results indicate that the thermal stability of theⅡb type diamonds is improved obviously by annealing process,however,while anneal temperature is getting higher and higher,the thermal stability ofⅡb type diamond single crystals appeares downtrend,so there is an optimum temperature annealed for the crystals.