铝合金微弧氧化放电火花对膜层粗糙度的影响

Influence of micro-arc oxidation discharge sparks on the surface roughness of aluminum alloy coating

为了探究铝合金微弧氧化膜层生长过程中的表面粗糙度变化,研究了氧化过程中放电火花随电压升高而表现出的阶段性特点,并分析其对微弧氧化膜层表面粗糙度的影响。将反应过程分为4个阶段,对氧化膜层形貌、厚度、表面粗糙度及膜层元素成分进行了分析,结合各阶段的火花状态讨论了表面粗糙度变化的可能原因。结果表明:在无火花阶段膜层粗糙度受基体表面粗糙度影响较大;白色小火花阶段形成细密的微弧氧化膜层,表面粗糙度逐渐降低;而后进入黄色小火花阶段,膜层生长速率增加,氧化物堆积膜层表面形成火山状突起,表面粗糙度变化出现拐点;当氧化进入橘黄色大火花放电阶段,火山状凸起更多,膜层表面粗糙度迅速增加。

In order to research the changes of the surface roughness of aluminum alloy micro-arc oxidation （ MAO） coating during the reaction process, different stages of the discharge sparks were investigated when the voltage in-creased during the oxidization process and the influences of the sparks on the surface roughness of the coating were also studied. The reaction process was divided into four stages;the shape, thickness, surface roughness and the el-emental composition of the coating formed in these stages were analyzed. The reasons why the surface roughness of the coating changed were discussed on the basis of the spark status at each stage. The results are shown as follows：in the stage without the spark, the surface roughness of the coating was influenced greatly by the matrix; in the stage with the white small spark, a compact oxide coating formed and the surface roughness decreased gradually;in the stage with the yellow small spark, the growth rate of the coating increased and oxide gathered on the coating surface and formed a volcano-like bulge. For this reason,the surface roughness began to increase. When the MAO reaction moved into the orange big spark stage, more volcano-like bulges appeared. In addition, the surface rough-ness of the coating increased quickly.