KH560处理对Al-Al2O3-硅烷复合涂层耐蚀性的影响

Effect of KH560 treatment on corrosion resistanceof Al-Al2O3-silane composite coating

对热浸镀铝-阳极氧化后的45钢在6%(体积分数)KH560硅烷溶液中进行不同时间的封孔处理,在45钢表面形成Al-Al2O3-硅烷复合涂层,研究复合涂层的微观组织及其对45钢的耐蚀性能和45钢-30%(质量分数,下同)Cf/nylon6复合材料的电偶腐蚀的影响。结果表明:硅烷涂层密封了Al2O3涂层的孔隙,阻止腐蚀液侵蚀基体,提高了45钢的耐蚀性;同时Al-Al2O3-硅烷复合涂层良好的绝缘性能使45钢与30%Cf/nylon6之间的电偶腐蚀的驱动力减小,改善其电偶腐蚀抗力。经5 min最佳KH560工艺处理后,试样的自腐蚀电流密度较单一热浸镀铝试样下降了3个数量级,电化学阻抗提高了2个数量级,与30%C f/nylon6复合材料偶接的电偶电流密度下降了约75%。

The 45 steel was sealing treated for various time in 6%(volume fraction)KH560 solution after the hot-dip aluminizing-anode oxidation.An Al-Al2O3-silane composite coating was formed on the surface of the 45 steel.The microstructure of composite coating was studied.The corrosion resistance of composite coating and its effect on the galvanic corrosion between the 45 steel and 30%(mass fraction)Cf/nylon6 composite were investigated.The results show that the silane coating effectively seals the cracks in Al2O3 coating,prevents the corrosive liquid from attacking the substrate.Hence,the corrosion resistance of the 45 steel is improved.Meanwhile,the good insulation property of the Al-Al2O3-silane composite coating can reduce the driving force of the galvanic corrosion between the 45 steel and 30%Cf/nylon6 composite,consequently,the galvanic corrosion resistance of 45 steel also is improved.After treated with the optimal KH560 treatment process for 5 min,the self-corrosion current density of the hot-dip aluminized 45 steel decreases by 3 orders of magnitude compared with that of the single hot-dip aluminized sample while the electrochemical impedance increases by 2 orders of magnitude,and the galvanic corrosion current density between the 45 steel and 30%Cf/nylon6 composite decreases by about 75%.