冷喷涂纯铝涂层硫酸阳极氧化层腐蚀行为研究  

Corrosion behavior of sulfuric acid anodized layer of cold sprayed pure aluminum coating

作　　者：代雪婷 南健 司永礼 胡家齐 宋圣强 DAI Xueting;NAN Jian;SI Yongli;HU Jiaqi;SONG Shengqiang(State-owned Machinery Factory in Wuhu,Wuhu 241007,China)

机构地区：[1]国营芜湖机械厂,安徽芜湖241000

出　　处：《粉末冶金工业》2024年第4期95-100,共6页Powder Metallurgy Industry

基　　金：芜湖市揭榜项目(JB20082)

摘　　要：为探究冷喷涂纯铝涂层硫酸阳极氧化层的防腐蚀效果,实验在两种不同孔隙率涂层表面制备硫酸阳极氧化层。通过SEM、EDS、中性盐雾试验和电化学试验,评价其组织、化学成分、耐蚀性能。结果显示,低孔隙率(0.8%)涂层虽因比表面积大,阳极氧化层厚度略低,但阳极氧化层致密度高,可形成致密钝化膜阻止材料进一步腐蚀。而高孔隙率(1.5%)涂层表面开放孔洞较多,机械加工过程进一步破坏了涂层表面连续性,电镀槽液沿涂层表面的孔洞渗入涂层组织内部,使涂层内部也发生了阳极氧化反应,破坏了涂层组织结构,使得涂层组织局部出现大于20μm的孔洞,未能形成致密钝化层。因此,高孔隙(1.5%)涂层钝化区窄,且维钝电流密度随着钝化电位增加而增大。与铝合金基底材料相比,涂层阳极氧化层的自腐蚀电流密度和维钝电流密度更高,其耐腐蚀性能劣于基体,且随着孔隙率增大呈下降趋势。但涂层阳极氧化层仍可耐受336 h中性盐雾腐蚀,满足飞机金属零件的防腐要求。为使涂层硫酸阳极氧化层具有和基体相近的耐蚀性能,并保证涂层致密度,建议尽可能减小涂层孔隙率。In order to explore anti-corrosion effect of sulfuric acid anodic oxide layer on cold sprayed pure aluminum coating,sulfuric acid anodic oxide coating was prepared on the surfaces of coatings with two kinds of porosity.The morphology,chemical composition and corrosion resistance were evaluated by SEM,EDS,neutral salt spray test and electrochemical test.The results show that for the low-porosity(0.8%)coating,although the thickness of anodic oxide layer is slightly lower than that of substrate due to large specific surface area,the density of anodic oxide layer is high,which can form a dense passive film to prevent further corrosion of materials.However,the high porosity(1.5%)coating has poor continuity of coating surface because of more open pores on the surface and the mechanical process.The electroplating solution penetrates into the coating structure along the pores on the coating surface,causing an anodic oxidation reaction inside the coating and damaging the coating structure.This phenomenon results in localized pores larger than 20μm in the coating structure,the coating fails to form a dense passivation layer.It causes that the passivation zone of high porosity(1.5%)coating is narrow,and the passive current density increases obviously with the increase of passivation potential.Compared with the aluminum alloy substrate,the self-corrosion current density and dimensional passive current density of the coating anodic oxide layer are higher,and the corrosion resistance is inferior to the substrate.Besides,the corrosion resistance decreases with the increase of porosity.However,the anodic oxide layer of the coating can still withstand neutral salt spray corrosion for 336 hours,meeting the anti-corrosion requirements of aircraft metal parts.In order to make the sulfuric acid anodized layer of the coating have a similar corrosion resistance to that of substrate and ensure the coating density,it is recommended to reduce the coating porosity as much as possible.

关 键 词：冷喷涂 纯铝涂层 孔隙率 硫酸阳极氧化 腐蚀行为 

分 类 号：TG174.4[金属学及工艺—金属表面处理]