采用热喷涂技术制备了Ni/Al-Ni/石墨系统封严涂层,研究了涂层在盐雾环境中的腐蚀性能.结果表明:Ni/石墨涂层在5 % NaCl饱和氧溶液中(质量分数,下同)的腐蚀电位为-382.3 mV ,在去氧溶液中的腐蚀电位为-848.2mV.Ni/石墨面层经盐雾腐蚀后,腐蚀产物主要为无定形Ni(OH)2·xH2O,腐蚀导致涂层表面石墨掉落,涂层腐蚀失重与腐蚀时间遵循幂指数函数.在腐蚀初始阶段,涂层的结合强度变化不大,但是经过480h的腐蚀后,涂层的结合强度明显下降,960h时结合强度与初始值相比下降30%左右.腐蚀机理研究表明,由于Ni/石墨涂层内部存在孔隙,腐蚀介质沿着孔隙通道向内渗透.孔隙中充满腐蚀介质后涂层内外溶液交换困难,在涂层的表面和内部形成宏观腐蚀电池,加速了涂层内部金属相的腐蚀.
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