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防护性镀层的作用在于防止腐蚀活性介质侵入零件基体金属表面。防护的可靠程度决定于防护性镀层的致密度,以及镀层金属本身的耐腐蚀性能与耐磨性能。镀层的致密度是指单位面积镀层中孔隙的多少。如果表面镀层有细微孔隙存在,腐蚀活性介质可通过孔隙渗入基体金属,以致引起基体金属锈蚀,降低镀层防护能力。因而要保证电镀质量,要求表面镀层应没有孔隙或孔隙数量控制在最小范围内,这样才能使表面镀层达到防护的目的。所以镀层孔隙
The role of protective coating is to prevent the corrosion of the active medium intrusion parts of the base metal surface. The reliability of protection depends on the density of the protective coating, as well as the corrosion resistance and wear resistance of the coating itself. The density of the coating refers to the number of pores per unit area of the coating. If there is fine pores in the surface coating, the corrosion-active medium can penetrate into the base metal through the pores, so as to cause the corrosion of the base metal and reduce the protective ability of the coating. Therefore, to ensure the quality of plating, the surface coating should be required to control the number of pores or pores in the minimum range, so that the surface coating to achieve the purpose of protection. So plated pores