铝合金焊接区喷射式微弧氧化陶瓷层耐腐蚀性研究

目的研究喷射式微弧氧化对改善铝合金焊接区耐腐蚀性能的可行性。方法使用自行研制的喷射式微弧氧化设备,在铝合金焊接区表面制备一层陶瓷膜,并在同等参数下制备一层浸入式微弧氧化陶瓷层进行对比。通过扫描电镜观察陶瓷膜表面和截面的微观形貌,并对陶瓷膜截面进行元素分析;分别利用铜加速盐雾腐蚀实验和动电位极化实验检测陶瓷膜的耐腐蚀性能,分析陶瓷膜的耐腐蚀性能。结果两种方法制备的陶瓷膜微观形貌相似,表面都有许多"火山口"状产物并伴有裂纹,截面疏松多孔,主要元素为Al和O;经240 h盐雾腐蚀后,3种试样均有不同程度的腐蚀,其中铝合金焊接基体腐蚀最严重,浸入式、喷射式次之,其腐蚀失重率分别是0.0072,0.0039,0.0023 g/cm2;极化曲线显示,铝合金基体、焊接基体、浸入式陶瓷膜、喷射式陶瓷膜腐蚀电位分别为-0.794,-0.742,-0.615,-0.578 V,耐腐蚀性依次增强。结论喷射式微弧氧化陶瓷层耐腐蚀性能表现较好,基本达到制备要求,在不适于浸入式微弧氧化的条件下可采用喷射式方法处理。

Corrosion Resistance of Ceramic Coatings Prepared by Spraying Micro-arc Oxidation on Aluminum Alloy Weld Zone

Objective To study the feasibility of using spraying micro-arc oxidation to improve the anti-corrosion property of aluminum alloy weld zone. Methods A ceramic coating was prepared on the aluminum alloy weld zone using a self-developed spraying micro-arc oxidation equipment, and compared with a ceramic coating prepared by immerging micro-arc oxidation using the same parameters. The surface and cross-section microstructure of the ceramic coating were observed by SEM, and the elemental composition of ceramic coating cross-section was analyzed. CASS corrosion test and potentiodynamic polarization curve experiment were used respectively to test the anti-corrosion performance of the coating, and analyze the corrosion resistance of the coating. Results The ceramic coatings prepared with the two different methods showed similar microstructure, there were many "craters" on the surface, accompanied by cracks. The cross-section was loose and porous. The major elements were Al and O. All three types of samples were corroded to varying degrees after 240 h salt spray corrosion. The aluminum alloy weld substrate was most severely corroded, followed by immerging and spraying samples, with corrosion weight loss ratios of 0. 0072,0. 0039,0. 0023 g / cm2 , respectively. The results of polarization curves showed that the corrosion potentials of aluminum alloy substrate, weld substrate, immerging ceramic coating and spraying ceramic coating were -0. 794, -0. 742, -0. 615 and -0. 578 V, respectively. Conclusion The corrosion resistance performance of ceramic coating prepared by spraying micro-arc oxidation was relatively good, reaching the preparation requirements. The spraying method could be used in conditions that the immerging method was not suitable.