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将AZ91D压铸镁合金于室温下浸渍在KH-550/乙醇/去离子水=5/80/15(体积分数)的混合溶液(水解时间2 h,p H=7~10)中90 s,取出经120℃×60 min固化处理制备了硅烷膜试样。采用电导率在线测量法研究了p H值对KH-550水解的影响,通过点滴试验、中性盐雾试验和电化学阻抗谱评价了硅烷膜的耐蚀性能。结果表明,当p H=9时,KH-550溶液同时具有最优的水解程度和稳定性;随p H值的增加,硅烷膜试样的耐蚀性能先上升后下降,当p H=9时,硅烷膜的耐蚀性能最佳。
AZ91D die-cast magnesium alloy was immersed in a mixed solution of KH-550 / ethanol / deionized water = 5/80/15 (volume fraction) for 2 h at pH = 7-10 for 90 s at room temperature, Silane film samples were prepared by solidification at 120 ℃ for 60 min. The influence of p H value on the hydrolysis of KH-550 was studied by on-line conductivity measurement. The corrosion resistance of silane film was evaluated by drop test, neutral salt spray test and electrochemical impedance spectroscopy. The results show that KH-550 solution has the best degree of hydrolysis and stability at p H = 9. With the increase of p H value, the corrosion resistance of silane film samples first increases and then decreases. When p H = 9 When the silane film corrosion resistance of the best.