A Description of the Copper Infiltration Process Used in Iron-Based P/M Parts

Some common methods and processing conditions used for the infiltration of copper into iron base structural components are briefly described in this article.

Infiltration is basically defined as "a process of filling the pores of a sintered or unsintered compact with a metal or alloy of a lower melting point." In the particular case of copper infiltrated iron and steel compacts, the base iron matrix, or skeleton, is heated in contact with the copper alloy to a temperature above the melting point of the copper, normally within the range of 2000¯ to 2100¯F (1095¯ to 1150¯C). Through capillary action, the molten copper alloy is drawn into the interconnected pores of the skeleton and ideally fills the entire pore volume.

Filling of the pores with higher density copper can result in final densities in excess of 95% of the composite theoretical value. Completely filled skeletons also allow for secondary operation such as pickling and plating without damaging the structure through internal corrosion. Pressure tight infiltrated components are also possible for specific applications that demand the absence of interconnected porosity.