金刚石表面非均匀形核法包覆氧化铝的动力学

采用非均匀形核法在金刚石颗粒表面包覆了一层Al2O3层,研究溶液pH值和Al(NO3)3的滴加量对其包覆率和覆层形貌的影响,分析其包覆的动力学方程。采用扫描电子显微镜(SEM)观察不同包覆阶段颗粒表面的覆层形貌。结果表明:当pH在4.5～5.5范围内,pH值越大,晶体长大系数越大,生长速率越快;溶液析晶过程受过饱和度影响,过饱和度越大,析晶驱动力越大。晶核孕育期受pH影响,滴加量相同的条件下,当pH在4.5～5.5范围内,pH值越大,晶核孕育期越短。

Dynamics of Alumina Coating on Diamond Particles by Heterogeneous Nucleation

Diamond particles with Al₂O₃ coating were prepared by using heterogeneous nucleation process. The effect of system pH and added amount of Al(NO₃)₃ on coating rate and its morphology were studied. Particle morphology was analyzed by scanning electron microscopy (SEM). The results show that in a certain range from pH 4.5 to 5.5, pH value affects the growth coefficient of crystal, the higher the system pH, the greater the growth coefficient. The crystallization process is related to the degree of supersaturation, the bigger the supersaturation of system, the greater the crystallization driving force. In a certain range from pH 4.5 to 5.5, higher pH is helpful for the nucleation process of alumina on diamond particles.