Relation between Sinter Ability and Initial Packing Density in Loosely Sintered Copper Sphere Compacts

Abstract

The dependence of some sintered properties on the initial packing density of copper sphere compacts was investigated in order to explain the relationship between sinterability and initial packing density for the loosely sintered product. Spherical copper powders with various initial packing densities were pressureless formed in a cylindrical quartz tube and sintered at the appropriate temperature. Sintered properties, shrinkage, electrical resistivity, and breaking strength, were measured and examined on the basis of simple geometrical model. These properties were found to be dependent on the initial packing density of the green compact. Sintering shrinkage and breaking strength increased with increasing initial packing density, whereas electrical resistivity decreased. The activation energy of the sintering process for the copper spheres was determined as 172·6 kJ mol⁻¹ and volume diffusion from the grain boundaries appeared to be the most plausible mechanism for sintering of the copper sphere compacts. PM/0436