Abstract
All sintered powder-metal structural parts produced by conventional methods of powder metallurgy are porous to a varying degree. This can be an advantage in certain applications, but where subsequent surface treatment is to be applied serious disadvantages become apparent.
Salt-bath hardening of low- and medium-density iron and steel parts results in excessive penetration of the hard case, as well as core embrittlement, and salt exudation invariably occurs. Both electroplating and barrel-plating of powder-metal parts cause problems, such as difficulty in getting the plate to strike, exudation of salts, internal corrosion, and surface spotting.
It is shown that pores can be effectively sealed by mechanically smearing the surface or impregnating the whole part with resin sealers; the choice will depend upon the subsequent treatment to be applied.
Get full access to this article
View all access options for this article.