电解液体系对镁合金微弧氧化膜的影响

Effects of the electrolytic solution on micro-arc oxidation coating of magnesium alloys

本文研究了电解液体系对镁合金微弧氧化膜层组织形态的影响.在碱性电解液（NaH2PO4/Na2SiO3/NaAlO2：5-20 g/L,NaOH：1-5 g/L,KF：5-8 g/L,Na3C6H5O7：0.5-2 g/L,EDTA：0.5-2g/L）中,以AZ91镁合金为基体制备出微弧氧化陶瓷薄膜,制备时采用恒电流控制模式,电流密度为10-30 A/dm2;采用扫描电镜（SEM）研究了氧化薄膜的微观结构.研究结果表明,电解液体系对微弧氧化膜层的表面形貌、微孔数量和半径都有很大的影响,在电解液中添加诸如甘油之类的有机物可改善膜层的表面质量.在上述工艺条件下,在硅酸盐体系中形成的膜层质量较好.

The effects of electrolytic solution on ceramic coating formed on AZ91 magnesium alloy substrate by micro-arc oxidation（MAO） was investigated.The coating was prepared in an alkaline electrolytic solution composed of 5-20 g/L of NaH2PO4/Na2SiO3/NaAlO2,1-5 g/L of NaOH,5-8 g/L of KF,0.5-2 g/L of Na3C6H5O7,and 0.5-2 g/L of EDTA,employing a constant-current controlled by AC power supply with a current density of 10-30A/dm2;and the microstructure of the coatings was characterized using scanning electron microscopy（SEM）.It was found that different electrolytic solutions had different effects on the morphology,pore number and pore radius of MAO coating.The coating formed in the electrolytic solution of silicate had a better quality than that formed in other two electrolytic solution.Moreover the electrolytic solutions with addition of some organic additive substance,such as glycerine,can improve the surface quality of the coatings.