摘要
采用以单质金属粉为主要原料的粉末冶金铁基触媒在国产六面顶压机上进行金刚石合成试验。利用扫描电镜(SEM)、场发射扫描电镜(FESEM)和原子力显微镜(AFM)对金刚石/金属包覆膜界面的微观形貌进行了细致表征。结果发现,未得以充分生长的金刚石表面存在宏观的晶体缺陷和明显的层状堆叠形貌;金属包覆膜上也会存在相应的复型和典型的台阶状形貌。充分生长的金刚石单晶表面依然存有大量高十几纳米的阶梯状或锯齿状生长台阶以及明显的位错蚀坑和形状规则的螺旋状生长台阶;金属包覆膜上也发现有阶梯状生长台阶的复型。分析认为,由于高温高压下金刚石晶体在触媒熔体中生长,作为杂质的触媒原子会在金刚石晶体表面造成大量的位错,金刚石依靠位错在晶体表面造成的台阶克服了形成二维晶核所需的较高的过饱和度和能量势垒,以层状堆叠的方式完成长大,即金刚石在高温高压下的生长是一种位错机制主导的层状生长。
The diamond synthesizing experiment was carried out at a cubic high pressure apparatus with ironbased catalyst made by powder metallurgy using pure-form metallic powders as main stuff. The micromorphology of the interface of diamond and metallic film was investigated by means of SEM, FESEM and AFM. The results indicated that if the normal grow process was interrupted; macroscopic crystal defects and obvious sandwich figured were left on the surface of diamond crystal, as well as the corresponding replica and obvious step-like figure on the metallic film. Even if the diamond grew fully, ladder-like or serrate growth steps with a length of over ten nanometers abound on the surface of the crystal, as well as obvious dislocation dip and helical grow steps. There is scalariform grow-step replica on the metallic film surroundings too. It can be concluded that the diamond crystal grows in the catalyst fusion at high-pressure and high-temperature （HP-HT）, catalyst atoms which act as impurity may result in much dislocation on the surface of the diamond. The steps which are caused by dislocation on the crystal surface will help the diamond overcome the supersaturation and energy barrier brought by the form stack. That means the grow process of process of planar nucleus, so the diamond diamond at HP-HT is a sandwich one with grows in the way of sandwich dislocation mechanism as the dominant way.
出处
《金刚石与磨料磨具工程》
CAS
北大核心
2008年第5期7-11,15,共6页
Diamond & Abrasives Engineering
基金
国家自然科学基金(50772060)
山东省自然科学基金(Y2007F12)
山东省博士后科研创新专项基金(200702024)资助项目
