电泳沉积法制备热子氧化铝绝缘层

Synthesis of Al_2O_3 Insulation Coatings on Mo-Substrates by Electrophoretic Deposition

基于Hamaker's law和静电场边界模型推导出考虑电场变化情况下沉积量与电泳条件的关系式,结合法拉第定律,使用溶液电流宏观地表征溶胶粒子沉积速率。分别改变电压和沉积时间进行电泳沉积实验,得到的沉积量与电压和时间的线性关系与本文推导出的公式一致。根据所得实验数据,在电泳条件下沉积60μm氧化铝,结果表明:涂层的表面特性主要受沉积时间影响,涂层的孔度主要由电压决定,电压40 V沉积6 s获得的热子氧化铝绝缘层性能最佳。

The Al2O3 insulation coatings were synthesized by electro-phoretic deposition on surfaces of Mo-heater. The electro-phoretic deposition of Al2O3 sol were mathematically modeled with Hamaker＇ s law and electrostatic field theo- ry, and theoretically calculated. The impact of the deposition conditions, including but not limited to the deposition rate, voltage and temperature,on the microstructures and properties of the Al2O3 coatings were investigated. The results show that the deposition rate and voltage all have a major impact on microstructures of the Al2O3 coatings. For example, high vohage resulted in a decrease of resistivity because of the increased porosity, originated from the H2 released in a faster re- action;but low voltage increased surface roughness due to a low deposition rate. Under the optimized conditions： deposited at 40 V for 6 s,high quality 60 tan thick compact Al2O3 layers were grown. In addition,the deposition rate,calculated with the newly-derived formula, agrees well with the measured result.