摘要
微弧氧化是在铝合金表面原位制备陶瓷膜层的一项新技术。针对陶瓷膜层在形成过程中的两次相变,分析计算Al2O3液相中的形核过程以及γ-Al2O3向α-Al2O3转变过程Gibbs自由能的变化,分析相变驱动力与温度及过冷度的关系。研究结果表明:约在1200 K左右过冷度时,可从液相Al2O3直接析出γ-Al2O3晶核,γ-Al2O3形核Gibbs自由能的变化符合T模型,α-Al2O3的形核行为可采用D-R模型计算,α-Al2O3和γ-Al2O3的均质形核率具有相同的数量级;微弧放电区域的热影响作用可造成γ-Al2O3向α-Al2O3的转变,温度为1500 K时转变驱动力比1100 K时增大了约12.3%。
Microarc oxidation is a new technique of making ceramic coating on the surface of aluminum alloy. The Gibbs free energy change of nucleation from liquid Al2O3 and transition from γ-Al2O3 to α-Al2 O3 are calculated during deposition of corundum. And the correlation of phase transition drive force with temperature and underoooling are analyzed. The calculated results show that the nuclei of γ-Al2O3 can directly nucleate from liquid under 1200 K undercooling or so. The Gibbs free energy change of γ-Al2O3 is accord with Turnbull model and the nucleation of α-Al2O3 can be calculated by Dubey-Ramachandrarao model. The homogenous nucleation rate of α-Al2O3 and γ-Al2O3 have same magnitude. The transition drive force from γ-Al2O3 to α-Al2O3 caused by thermal effect of microarc discharge will increase 12.3 % as temperature increase from 1100 K to 1500 K.
出处
《电镀与环保》
CAS
CSCD
2006年第2期33-35,共3页
Electroplating & Pollution Control
基金
航天科技创新基金"稀土高强铝锂合金微弧瓷质化及其成膜机理研究"
关键词
微弧氧化
Gibbs自由能
过冷度
相变
microarc oxidation
Gibbs free energy
undercooling
phase transition
