材料期刊网

目的：解决金属镀金外壳在NaCl盐溶液中表面出现锈蚀、外壳引线根部断裂的问题,提高外壳的抗盐雾腐蚀能力,解决外壳镀层抗蚀性差的问题。方法以盐雾腐蚀机理为依据,利用扫描电镜对镀金外壳在盐雾环境中的腐蚀形貌进行观测,分析镀层腐蚀形貌和金属基座(可伐合金)-玻璃绝缘子(电真空玻璃)-金属引线(可伐合金)封接形貌。从4个方面对工艺进行改进：控制金属镀层与基体材料的电位差,消除腐蚀原动力；提高镀层致密性,减少镀层孔隙率；控制外壳高温封接温度,抑制缝隙腐蚀；控制金属表面镀层厚度,防止镀层与基体间形成腐蚀通道。结果针对镀金外壳在盐雾环境中的腐蚀形态以点蚀、缝隙腐蚀为主的情况,通过优化镀镍工艺、镀金工艺,避免腐蚀发生时金属外壳表面形成大面积点蚀；优化高温退火温度为800℃,高温封接温度为900℃,可以抑制金属外壳缝隙腐蚀的发生。结论优化金属外壳退火温度、高温封接温度、电镀镍和金等工艺措施,提高了金属镀金外壳抗48 h盐雾腐蚀性能。

ABSTRACT:Objective To solve the problems of surface rust appearing on the gilded metal shell in Nacl salt solution and root breakage of the shell wires, and to improve the ability of anti-48 h salt spray corrosion of the shells, so as to figure out the problem of poor corrosion resistance of the coating. Methods According to the mechanism of salt spray corrosion, the morphology of gilded shells in the salt spray corrosion was observed with SEM. Then, the corrosion morphology of the coatings and sealing morphology of metal base ( Kovar)-glass insulators ( electric-vacuum glass)-metal lead ( Kovar) were analyzed. By controlling the potential differ-ence between the metal coating density, reducing the coating porosity, controlling the sealing temperature of the carton, inhibiting the crevice corrosion and controlling the coating thickness of the metal surface, thus the formation of the corrosion channel between the coating and the substrate can be prevented. Results The corrosion shapes of the gilded shells mainly present as pitting and crev-ice corrosion. Large area of pitting corrosion can be avoided on the metal surface by optimizing the process such as nickel and gold plating;and the crevice corrosion on the metal shells can be inhibited by optimizing the annealing temperature and the sealing tem-perature to be 800 ℃ and 900 ℃, respectively. Conclusion By optimizing the annealing temperature, sealing temperature, nickel plating, metal plating and other process, the ability of anti-48 h salt spray corrosion of the metal gilded shells can be effectively im-proved.