Effects of process parameters on steel foam synthesis

The effects of simple process parameters used for making steel foams by powder metallurgical (P/M) synthesis were investigated. Different powder blending methods and melting times were employed and the effects on the geometric structure of steel foam were examined. Powder blending was critical to achieving a homogeneous distribution of foaming agent because of the density disparity between steel and foaming agent powders. Dispersion of the foaming agent affected the pore size distribution of the expanded foams. Foam expansion was accomplished by melting powder compacts, and the time above the melt temperature affected the pore structures within the foams. With increasing melt time, pores coalesced, leading to the eventual collapse of the foam. Inserting interlayer membranes in the powder compacts inhibited coalescence of pores and produced foams with more uniform cell size and distribution.