铜合金表面微弧氧化膜的制备及其耐蚀绝缘性能研究

Insulation and corrosion resistance of plasma electrolyticoxidation coatings on copper alloy

采用铝酸盐电解液体系在铜合金表面成功制备了微弧氧化膜,并考察了其腐蚀防护与绝缘性能。通过扫描电子显微镜(SEM),X射线能量色散谱仪(EDS),X射线衍射仪(XRD)表征了氧化膜的微观形貌及结构组成。利用电动位极化曲线、电化学阻抗谱及盐雾试验箱综合评价了氧化膜的腐蚀防护性能。通过耐压测试仪测试了氧化膜在交流和直流模式下的电压与漏电流关系曲线。结果表明,铜合金表面微弧氧化膜生长以向外生长的化合物沉积为主,呈现明显的边缘效应,并随氧化电压的升高,铜合金基体参与氧化成膜的程度越高,氧化膜的厚度也越大,其腐蚀电流密度相较于铜基材降低了3个数量级,中性盐雾测试732 h后无明显腐蚀产物,在直流和交流模式下的耐击穿电压分别提升至750 V和600 V,说明铜合金微弧氧化膜在高电压下具有较快的生长速度和优异的耐腐蚀与绝缘性能。

The plasma electrolytic oxidation coatings(PEO coatings)with corrosion protection and insulation properties were prepared on copper alloy by aluminate electrolyte system.The microstructure and structural composition of the PEO coatings were characterized by scanning electron microscope(SEM),X-ray energy dispersive spectrometer(EDS)and X-ray diffrotometer(XRD).The corrosion protection of the PEO coatings were evaluated by electrochemical and salt spray corrosion test.The leakage current and voltage of the PEO coatings under AC and DC conditions were measured by puncture tester.The results show the PEO coatings on copper alloy surface tends to grow outward in form of electrolyte deposition.As the oxidation voltage increased,more of the copper alloys were oxidized,and the PEO coatings was thicker.The corrosion current density decreased by 3 orders of magnitude compared with copper substrate,and no obvious corrosion products were found after 732 h neutral salt spray test.The breakdown voltage in DC and AC modes were increased to 750V and 600V respectively.The PEO coatings prepared in high voltage had higher growth rate and showed excellent corrosion resistance and insulation performance.