表面处理对Al-Li合金胶接性能与耐腐蚀性的影响

目的提高铝锂合金胶接接头的强度与耐腐蚀性能。方法对铝锂合金板采用砂纸打磨、喷砂和磷酸阳极化处理,在表面处理后的基板上铺一层FM94胶,并加压固化,得到单搭接接头。分析不同表面处理后铝锂合金试样的表面形貌、表面粗糙度、表面自由能和表面化学组成,对接头进行湿热环境老化实验,测试湿热老化前后胶接接头的强度,研究揭示不同表面处理方法对胶接接头强度与抗湿热老化能力的影响。结果与砂纸打磨后的试样相比,喷砂与磷酸阳极化处理能显著提高铝锂合金试样的表面粗糙度和表面自由能。同时,经EDS分析发现,阳极化后铝锂合金表面氧元素大量增加。阳极化和喷砂处理后的接头强度分别为37.0、26.8MPa,而简单打磨过后的接头仅为16.4MPa。湿热老化后,磷酸阳极化处理的接头强度仅下降12.2%,而喷砂处理和砂纸打磨处理的接头强度分别下降了30.6%和19.5%。结论磷酸阳极化和喷砂处理均能增大铝锂合金胶接接头的强度,但阳极化处理效果更好,阳极化处理能显著加强接头的耐腐蚀能力,而喷砂处理则对接头的耐腐蚀能力无明显提升。

Effects of Surface Treatment on Bonding Properties and Corrosion Resistance of Al-Li Alloy

The paper aims to improve the strength and corrosion resistance of aluminum-lithium alloy bonded joints. Surface treatments including sandpaper polishing, sandblasting and phosphoric acid anodizing were applied to Al-Li alloy. After surface treatment, a layer of FM94 adhesive was laid on the substrate and pressurized to cure to obtain a single lap joint. The surface properties of alloy samples including surface morphology, surface roughness, surface free energy and surface chemical composition were analyzed. The strength of the bonded joints before and after hot-humid exposure was tested, respectively to reveal the effects of different surface treatment methods on the strength and corrosion resistance of the bonded joints. Compared with sandpaper polished alloy samples, sandblasting and phosphoric acid anodizing treatments could significantly improve the surface roughness and surface free energy of aluminum-lithium alloy samples. At the same time, it was found by EDS analysis that the surface of the anodized alloy samples had a large amount of oxygen. The joint strength of anodized and sandblasted joints was 37.0 MPa and 26.8 MPa, respectively. However, that of sandpaper polished joints was only 16.4 MPa. After hot-humid exposure, the strength of phosphoric acid anodized joints was only decreased by 12.2%. However, the strength of joints after sandblasting and sanding treatment was decreased by 30.6% and 19.5%, respectively. Both anodizing and sand blasting surface treatments could increase the strength of the Al-li alloy bonded joint; however, the anodizing effect is better. The anodizing treatment can significantly enhance the corrosion resistance of the joint. However, the sandblasting treatment does not significantly improve the corrosion resistance of the joint.