氧气流量对LY12铝合金微弧氧化膜致密性的影响

Effect of oxygen flow on compactness of micro-arc oxidation coatings on LY12 Al alloy

通过调整工艺参数与氧气流量在LY12铝合金表面获得均匀、致密的微弧氧化膜层。利用SEM、XRD及电化学工作站等研究膜层的厚度、微观形貌、相组成以及耐腐蚀性能,讨论通氧微弧氧化作用机制,并分析氧气流量对膜层致密性的影响。结果表明:膜层厚度随电压、氧化时间和电解液组分浓度的增加呈规律性变化;氧气的助烧结作用能促进致密层的生长,随着氧气流量的增加,致密层厚度呈现先增加后减小的规律;KF 105g/L,KOH 85g/L,NaAlO_2 12g/L,电压110V,氧化时间15min,氧气流量为0.010L/s时得到厚度30μm的致密膜层,自腐蚀电位提高至-0.11V,腐蚀电流密度下降至2.1×10^(-6)A/cm^2,比铝合金基体降低2个数量级以上,表现出良好的耐腐蚀性。

Compact and uniform coatings were fabricated on LY12.aluminum alloy surface by adjusting process parameters and oxygen flow after micro-arc oxidation (MAO) treatment. The thickness, morphology, phase compositions and corrosion resistance were examined by SEM, XRD and electrochemical test system. The mechanism of MAO with oxygen was discussed, and the effect of oxygen flow on the coating compactness was analyzed. The results indicate that with the increase of time, voltage and concentration of electrolyte, the coating thickness changes regularly. The effect of oxygen on sintering can promote the growth of compact coatings, and the thickness of compact coatings first increases and then decreases with O2.rising. Under the conditions of105g/L KF, 85g/L KOH,12g/L NaAlO2,110V for the voltage,15min for treatment time and 0.010L/s for oxygen flow, a 30μm-thick compact coating can be formed on LY12.aluminum alloy. The corrosion potential of the coating increases to -0.11V, and the current density reduces to2.1×10 -6 A/cm2, which is reduced by two orders of magnitude compared with the matrix and the corrosion resistance of the LY12.aluminum alloy significantly improves.