通常,金属零件的表面都要求耐磨、耐腐蚀、耐热、美观等等,但从整体来讲,又要求有一定的强度、韧性,并且重量轻、成本低,如柱塞、凸轮、齿轮等零件。在采用单一材料不能满足这些要求时,应采用表面与内部为不同材料的被覆型复合压形体。以往采用的方法是:将加工成形的零件用电镀、喷镀、蒸镀或热压等手段在其外部覆盖一层金属材 Generally, the surface of the metal parts are required to be wear-resistant, corrosion-resistant, heat-resistant, aesthetically pleasing and so on. However, on the whole, a certain strength and toughness are required, and the weight and cost are low such as plungers, cams, And other parts. In the use of a single material can not meet these requirements, the surface and the interior should be of different materials coated composite compact. The method used in the past is: the processing of the shape of the parts with plating, spraying, evaporation or hot pressing and other means covered in its outer layer of metal