含Zn-Al磷酸盐防腐蚀涂层的制备与腐蚀机理研究

为制备出具有更高耐蚀性、尤其是耐海洋气候腐蚀的Zn-Al基金属陶瓷涂层,以磷酸二氢铝作为粘结剂,氧化镁、氧化锌作为固化剂,锌、铝粉作为填料,聚四氟乙烯作为助剂,制备了一种含Zn-Al磷酸盐防腐蚀涂料,通过空气喷涂后热固化的方式在300M高强钢表面制备出含Zn-Al磷酸盐防腐蚀涂层,并对涂层进行了中性盐雾试验以及电化学试验,采用扫描电镜和能谱分析形貌及成分。结果表明:涂层中性盐雾腐蚀寿命达到1 000 h;涂层的自腐蚀电位低于基体,能为基体提供阴极保护;含Zn-Al磷酸盐防腐蚀涂层的腐蚀过程分为4个阶段,涂层的主要防护机制为金属粉的牺牲阳极作用和腐蚀产物的屏蔽效应。

Preparation and Corrosion Mechanism Research of Anticorrosive Phosphate Film Containing Zn-Al

Anticorrosive phosphate coating containing Zn-Al was prepared using chrome aluminum phosphate as binder,magnesium oxide and zinc oxide as curing agent,zinc and aluminum powders as filler,and Teflon as adjuvant.By aerial spraying and post-thermofixation method,the Zn-Al phosphate anticorrosive film was prepared on the surface of 300M high strength steel,and then the film was evaluated by neutral salt spray and electrochemical test.In addition,the morphology and composition were characterized by scanning electron microscope and energy dispersive spectrometer.Results showed that the neutral salt spray life of film reached 1 000 h,and the free corrosion potential of film was lower than that of substrate,which could provide cathodic protection for substrate.The corrosion process of anticorrosive phosphate film containing Zn-Al was divided into 4 stages,and the main protective mechanisms of film were the sacrificial anode effect of metal particles and the shielding effect of corrosive production.