SiC_p/Al复合材料化学镀镍层耐蚀性能及机理研究

CORROSION RESISTANCE OF ELECTROLESS Ni COATINGS ON SiC_p/Al COMPOSITE AND MECHANISM

在考察镀覆条件对镀层含磷量影响的基础上,用电化学方法评价不同含磷量镀层的耐蚀性,得到基本一致的结果:镀液温度及pH值降低,镀层磷含量升高,而镀层含磷量的提高又使镀层的耐蚀性提高.用SEM、EDAX和XRD研究了镀层的表面和断面形貌、含磷量以及相结构,探讨了碳化硅颗粒增强铝基(SiCp/Al)复合材料表面化学镀镍层耐腐蚀的机理.结果表明,在腐蚀过程中,镀层中磷元素在表面富集形成具有良好耐蚀性的钝化膜,从而提高镀层的自钝化能力和耐蚀性.

Ni - P coatings were prepared on SiCp/Al composite by autocatalytic deposition and their corrosion behaviors in 3.5 96 NaCI solution at 25℃ were studied by electrochemical impedance spectroscopy and potentiodynamic techniques. SEM, EDAX and XRD were also employed to examine the coatings so as to understand the corrosion mechanism of the coatings. The plating conditions show great influences on the P content of the coatings and thus the corrosion resistance. The P content of the coatings increases with decreasing the plating temperatures and pH values. The corrosion resistance of the coating can be increased significantly by increasing the P content of the coatings, whieh is ascribed to that the existence of P can improve significantly self passivation of the coatings in the solution.