高Si压铸Al合金ADC12的微弧氧化表面改性

SURFACE MODIFICATION OF DIE CASTING Al ALLOY ADC12 WITH HIGH Si CONTENT BY MICRO-ARC OXIDIZATION

利用恒流微弧氧化技术,在以Na2SiO3和Na3PO4为主盐的电解液中,在高硅压铸Al合金ADC12表面制备了 陶瓷膜．显微硬度及耐蚀性能测试表明,陶瓷膜显微硬度(HV)高达1430,能对基体金属提供有效的防护．涡流测厚及SEM研 究显示,该陶瓷膜厚度分布比较均匀,具有双层结构． EDX和XRD分析表明,该微弧氧化陶瓷膜的主要元素组成为O,Al, Si和P;主要相组成为γ-Al2O3和α-Al2O3,同时含有少量χ-AlO23,θ-A1203和Al2SiO5晶体．

Ceramic coating on the surface of die casting Al alloy ADC12 with high Si content has been prepared by micro-arc oxidization （MAO） in an electrolyte containing Na2SiO3 and Na3PO4 as its major compositions at constant current density. The testing results of hardness and corrosion protection indicate that the obtained ceramic coating has relatively high microhardness （HV up to 1430） and could provide effective protection to substrate. Eddy currency thickness measurement and SEM micrographs manifest that the ceramic coating consists of a double-layer structure and its thickness is relatively even. EDX and XRD analyses reveal that the main elements in the coating are O, Al, Si as well as P, and that the main phases are γ-Al2O3 , α-Al2O3. In addition small amounts of χ-Al2O3,θ-Al2O3 and Al2SiO5 are also detected.