离子镀铝与离子液体电镀铝涂层性能对比研究

目的对比研究离子镀铝和离子液体电镀铝两种涂层的性能。方法针对高强度钢表面环保表面处理的需求,对比研究300M钢表面离子镀铝和离子液体电镀铝两种涂层,采用扫描电子显微镜(SEM)、能谱(EDS)等对两种涂层的表面、断面微观形貌和成分进行表征;采用原子力显微镜(AFM)对两种涂层表面三维形貌和粗糙度进行观察和测量;采用电偶腐蚀测试两种涂层与铝合金的电偶腐蚀性能;采用缺口试样拉伸方法检测两种涂层对300M钢基体氢脆性能的影响;采用5%Na Cl人工海水周浸试验的方法检测两种涂层的耐蚀性能,与电镀镉钛镀层进行对比,采用电化学方法对涂层试验前后的阻抗谱特性进行检测分析。结果两种涂层表面形貌存在较大差异,离子镀铝经过致密化处理后,表面为均匀的圆饼状形貌,致密度很高,粗糙度约为0.88μm,而离子液体电镀铝涂层表面则为圆顶状的凸起物组成,没有明显的孔洞缺陷,粗糙度约为0.71μm;电偶腐蚀测试显示,两种涂层都能够与铝合金相容连接;缺口试样的拉伸试验结果显示,两种涂层的对基体的氢脆性能没有影响;腐蚀试验结果显示,两种涂层对于300M钢基体都具有良好的保护效果,与传统的电镀镉钛相当,具备了未来替代镉类镀层的潜质。结论两种涂层均匀致密,没有明显的气孔、裂纹等缺陷,电偶腐蚀性能优异,对300M钢基体都不会产生氢脆隐患,耐蚀性能优异。

Comparison Study on Performance of IVD and ILEp Aluminum Coatings

Objective To have comparative study on performances of IVD and ILE aluminum coatings.Methods In allusion to the requirement of environmental treatment on high-strength steel surface, two aluminum coatings were formulated on 300M steel and studied. The morphology of surface and cross section of the two coatings were characterized by scanning electron mi-croscope (SEM) and energy dispersive spectrometer (EDS). Atomic force microscope (AFM) was applied to observe the mor-phology and measure the roughness of the coatings. The contact corrosion was tested between the two aluminum coatings and aluminum alloy. Influences of two coatings on the hydrogen brittleness was evaluated by tensile test of notched bar. The corro-sion resistance of the two coatings was tested by neutral salt spray and alternative immersion in artificial seawater. It was also compared with the cadmium plating coating. Electrochemical method was conducted to evaluate the changes of impedance spectroscopy property during the corrosion test.Results Surface topographys of the two coatings were much different. After densifying treatment, the IVD Al coating exhibited uniform round concave pits withroughness of 0.88 μm, which is attributed to shot preening process. The Alep Al coating has a typical morphology of electroplating composing of convex parts, with rough-ness of 0.71μm. The two aluminum coatings came into contact with aluminum alloy without little galvanic corrosion risk. The notched bars did not break after a 200 h tensile test, suggesting no hydrogen brittleness was introduced into the substrate. The two aluminum coatings exhibited excellent corrosion resistance. The main indexes including hydrogen brittleness and corrosion resistance were equal to that of cadmium plating.ConclusionThese two coatings are uniform and tight, and are free from ob-vious defects such as porosity and crack. They have galvanic corrosion performance, and won't produce hydrogen embrittlement of 300M steel matrix. Their corrosion resistance is excellent.