共晶铝硅合金恒流微弧氧化成膜工艺优化

Optimization of galvanostatic micro-arc oxidation on eutectic Al-Si alloy

采用恒流氧化模式对二元共晶Al-Si合金进行微弧氧化(MAO)处理。在碱性电解液体系中,以Na_(2)SiO_(3)和C6H12N4(六次甲基四胺)质量浓度、电流密度、脉冲频率和占空比为优化对象,以膜层的耐腐蚀性能、生长速率及成膜的单位能耗同时作为评价指标,通过正交试验得到以下最优成膜工艺:电解液由12 g/L Na_(2)SiO_(3)、2 g/L NaOH和5 g/LC_(6)H_(12)N_(4)组成,正、负向电流密度分别为10 A/dm^(2)和4 A/dm^(2),脉冲频率400 Hz、占空比25%,单个周期的正负脉冲数之比为1。该工艺显著降低了Si相对共晶铝硅合金上MAO的不利影响。

The eutectic Al–Si binary alloy was treated by micro-arc oxidation(MAO)galvanostatically in an alkaline electrolyte.The MAO process parameters were optimized based on orthogonal test with the mass concentrations of Na_(2)SiO_(3) and LC_(6)H_(12)N_(4)(methenamine),current density,pulse frequency,and duty cycle as the factors by evaluating the corrosion resistance and growth rate of MAO film as well as the specific energy consumption during MAO.The optimal composition of the electrolyte is Na_(2)SiO_(3)12 g/L,NaOH 2 g/L,and LC_(6)H_(12)N_(4)5 g/L,and the optimal process conditions are:positive current density 10 A/dm^(2),negative current density 4 A/dm^(2),pulse frequency 400 Hz,duty cycle 25%,and positive-to-negative pulse number in a period 1.This process greatly reduces the adverse effect of Si on the MAO of eutectic Al–Si alloy.