Relationship Between Porosity and Spacer Content of Open Cell Metal Foams

Metal foams with high melting points are generally fabricated by the space holder technique. Foams with desirable pore size, shape and distribution can be obtained by using appropriate space holder. However, porosity (P) is always not equal to spacer content (ϕmac), which makes it difficult to obtain the expected porosity. In this study, a model equation for describing the relationship between P and ϕmac was established based on theory, i.e., P = (a1ϕmac + a2)/(a3ϕmac + a4). Each coefficient ai (i.e., a1, a2, a3, a4) could be determined by the porosity of cell walls (Pcell wall) and the volume change rate of macropores (Rmac). The theoretical equation was in accordance with the experimental results by authors and in the studies. It implies that Pcell wall and Rmac can be considered as constants in one certain production condition.