高温热蒸发法在金刚石表面镀覆SiO_2的形貌与形成机理

采用高温热蒸发法在金刚石表面镀覆SiO_2,用扫描电镜(SEM)、X线衍射(XRD)和能谱分析对SiO_2的形貌与物相组成进行观察与分析,研究SiO_2晶体的生长机制。结果表明,在较低温度下(1 300℃)金刚石表面生成SiC和SiO_2颗粒,无法形成涂层。温度升高到1 400℃时,金刚石表面形成许多由C,Si,O元素组成的细小蝌蚪状组织。当温度升高到1 500℃时,金刚石表面镀覆良好的Si-O涂层,Si-O涂层上有许多SiO_2晶粒、微米棒与晶须。SiO_2晶体的生长机制为:首先在金刚石表面沉积一层Si-O涂层,然后在该涂层上析出SiO_2颗粒,在SiO_2颗粒上进一步形成新的SiO_2颗粒和晶须。

Microstructure and formation mechanism of SiO2 coating on the surface of diamond prepared by high temperature thermal evaporation

SiO2 coating was prepared on the surface of diamond by using high temperature thermal evaporation method. The phase composition and microstructure of the products were studied by using XRD, SEM and EDS. The growth mechanism of SiO2 grains was also explored. The results show that no SiO2 coating but SiC and SiO2 particles form on the surface of diamond at a low temperature (1300℃). When the heat treatment temperature is 1400℃, many tadpole-like microstructures composed of C, Si and O elements appear on the surface of diamond. When the temperature is 1500℃, Si-O coating with different morphologies forms on the surface of diamond. The growth mechanism of SiO2 crystalline is proposed. Firstly, Si-O coating forms on the surface of diamond. And then, SiO2 grains precipitate on it. Finally, new SiO2 grains or whiskers form on the SiO2 grains.