Homogeneity of the porous structure of permeable powder-metallurgy materials

Conclusions

When the ratio of the mold diameter to the mean powder particle diameter is not less than 22 and the ratio of the thickness of the product to the moid diameter is not more than 1∶1, then the homogeneity of the porous structure of material is not influenced by the wall effect or by the nonuniformity of stress distribution across the thickness during molding.

When the thickness of the layer of material increases, its porous structure becomes statistically averaged on account of the smaller number of pores of maximal and minimal size and the larger number of average-size pores.

With decreasing particle size of powder or increasing specific surface, the critical thickness of a layer of material characterizing the transition to homogeneous porous structure increases. Other conditions being equal, the shape of the powder particles has the decisive influence on the critical thickness.