镁合金微弧氧化陶瓷层表面的电泳成膜机理

Formation mechanism of electrophoretically deposited organic layer on PEO film of magnesium alloy

研究镁合金微弧氧化(PEO)陶瓷层表面的电泳成膜机理;分析工艺参数对复合膜层耐蚀性的影响。采用扫描电镜、示波器和盐雾试验机等分别研究复合膜层的表面和截面形貌、电泳过程中电流变化规律及腐蚀防护性能。结果表明:在电泳成膜过程中,微弧氧化陶瓷层微孔处被击穿,电泳回路产生电流,电泳漆带电粒子先在微孔处沉积,然后向周围移动并沉积,当电流降为0时,电泳过程结束。随着陶瓷层厚度和粗糙度的增加,陶瓷层被击穿时间延长,电泳漆粒子沉积时间缩短。微弧氧化陶瓷层的腐蚀速率是微弧氧化/电泳涂装复合膜层的6.286倍,说明镁合金微弧氧化陶瓷层经电泳处理后,其耐蚀性得到了显著的增强。

The formation mechanism of organic layer within ceramic layer by the electrophoretic deposition（EPD） was investigated.The influence of processing parameters on the corrosion resistance of the composite coating was analyzed.The surface and cross-section morphologies,variation of current in the EPD and corrosion protection were evaluated using scanning electron microscope,oscilloscope and salt spray tester,respectively.The results indicate that the breakthrough and current appears in the EPD process.As a result,the charged particles in electrophoretic paint are firstly deposited within micropores on the ceramic layer,and then spread out.When the current of the EPD becomes 0,the electrophoretic deposition is completed.A long time for breakthrough and a reduction for the EPD time occur with the increase of the thickness and roughness of the ceramic layer.The corrosion rate of the PEO coating is 6.286 times as fast as that of the composite coating.This is of practical significance for magnesium alloys in the formation of organic layer within ceramic layer to improve corrosion resistance.