阳极氧化对半固态成形ZL114A合金铸件耐蚀性能的影响

Effect of anodizing on corrosion resistance of ZL114A alloy castings prepared by semi-solid cast process

研究了阳极氧化工艺和表面液相偏析层对半固态成形ZL114A合金铸件耐蚀性的影响。结果表明:对于阳极氧化而言,表面液相偏析层会显著影响氧化膜生长速率,使得氧化膜厚度减小,但由于膜层平整,反而有利于氧化膜对合金耐蚀性能提高;然而,去除表面液相偏析层虽然会增加试样表面氧化膜的厚度,但由于这种氧化膜分布不均匀,从而无法提高合金的耐蚀性。未经阳极氧化处理的试样耐蚀性分析结果表明,表面液相偏析层的存在会降低试样的耐蚀性,去除表面液相偏析层会在一定程度上提高耐蚀性。对氧化膜腐蚀后的蚀坑研究发现,共晶组织对氧化膜的蚀坑的形成起着决定性作用,蚀坑通常位于共晶组织部位,且在蚀坑中往往发现有富铁金属间化合物。

Effect of anodizing process and surface liquid segregation layer on corrosion resistance of ZL114A alloy castings prepared by semi-solid cast process was studied.The results show that for anodizing process,the surface liquid phase segregation layer will significantly affect the growth rate of the anodized film,reducing the thickness of the anodized film,but because the film is uniform,it is beneficial to improve the corrosion resistance of the alloy.However,although the removal of the surface liquid phase segregation layer will increase the thickness of the anodized film on the surface of the sample,due to the uneven distribution of the anodized film,the corrosion resistance of the alloy cannot be improved.The corrosion resistance analysis results of the samples without anodizing treatment show that the existence of surface liquid phase segregation layer will reduce the corrosion resistance of the samples,and the removal of surface liquid phase segregation layer will improve the corrosion resistance to a certain extent.The research on the etch pits after the corrosion of the anodized film shows that the eutectic structure plays an important role in the formation of the etch pits of the anodized film.The etch pits are usually located in the eutectic structure,and the Fe-rich intermetallic compounds are often found in the etch pits.