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近年来,为了降低成本,以铸件与粉末冶金件来取代以往使用的无内部孔穴的车削件的情况多起来了。尤其粉末冶金件,使用在小型零件上,随着生产率的提高,必然相应增加铸件与粉末冶金件的表面处理工作。一般认为,金属的表面处理与金属内部结构没有直接关系,但也不应忽视。铸件与粉末冶金件这类零件,在制造时坯体的内部构造就有很多孔穴,而且布满表面。表面的凹凸虽未达到很严重的程度,但若使用在水溶液中进行的表面处理方法,有时处理液浸入金属内部后,仍不能电镀;有时表面看上去很漂亮的镀层会从内部膨胀,发生腐蚀、变色,特别是粉末冶金件的机械强度将显著降低。
In recent years, in order to reduce the cost, cast parts and powder metallurgy parts have been used instead of the conventional parts for turning parts without internal holes. In particular, powder metallurgy parts, used in small parts, with the increase of productivity, inevitably increase the surface treatment of castings and powder metallurgy parts. Generally believed that the metal surface treatment and the internal structure of the metal is not directly related, but should not be overlooked. Parts such as castings and powder metallurgy parts have many cavities in the internal structure of the body as they are manufactured and are full of surfaces. Although the surface unevenness is not very serious, the surface treatment method using an aqueous solution sometimes causes the plating solution to remain electroplated even after it is immersed in the metal. In some cases, the plating may appear to be beautifully expanded and corroded , Discoloration, especially the mechanical strength of powder metallurgy parts will be significantly reduced.