粉末置换包覆的热力学及其影响因素  

Thermodynamics and the Influencing Factors of Substitutive Coating on Powder

作　　者：高家诚[1] 吴世学[1] 王勇[1] 孟繁琦[1] 

机构地区：[1]重庆大学材料科学与工程学院,重庆400030

出　　处：《材料导报》2006年第F05期251-253,257,共4页Materials Reports

摘　　要：从热力学角度分析了置换包覆粉末的原理,并探讨了原料粉末、镀液浓度、温度、搅拌速度、添加剂等因素对置换包覆的影响。通过热力学计算表明,置换反应速度随镀液浓度的增大和温度的升高而增大。过程为化学反应控制时,搅拌不影响置换包覆速度;过程为扩散控制时,随着温度升高,置换包覆速度增加。镀液pH值过大会发生析氢反应,过小会使金属离子水解降低置换包覆速度。另外在镀液中加入合适的添加剂有利于改善镀层的质量。This essay analyzes the principle of substitutive coating on powder by means of thermodynamics, and discusses the influencing factors of substitutive coating, e. g. original powder, concentration of plating solution, temperature, stirring speed, and addition agents. Thermodynamic calculations clarify that the substitution reaction is accelerated by the rise in concentration and temperature of plating solution. In condition of chemical reaction control, stirring does not affect the speed of substitutive coating, while in condition of diffusion control, the rising temperature speeds up the substitutive coating. This essay also clarifies that over-high pH of plating solution generates the reaction of hydrogen liberation, and over-low pH causes hydrolytic decomposition of metal ions and accordingly slows down the speed of substitutive coating. In addition, appropriate addition agents are helpful to improve the coating quality in plating solution.

关 键 词：热力学 包覆粉末 置换镀 

分 类 号：TQ174.758[化学工程—陶瓷工业]