Investigation on compaction behaviors of Ag35Cu32Zn33 mixed metal powders under cold die compaction

Abstract

Series experiments were performed to investigate the cold die compaction behaviors of Ag35Cu32Zn33 mixed metal powders to manufacture thin sheet of cadmium-free silver based filler metal, and the effect of friction on powder compaction behaviors were analyzed using the finite element method (FEM). The density dependent modified Drucker-Prager Cap model was established to characterize the mixed metal powders compaction behaviors. The die wall friction coefficients under different lubricated conditions were experimentally determined and were modeled by Coulomb friction model in simulations. The established constitutive model and material parameters were validated by experiments and finite element simulations of powder compaction process in ABAQUS/Standard with a user subroutine USDFLD. The compaction mechanisms of Ag35Cu32Zn33 mixed metal powders were analyzed with Gerdemann-Jablonski compaction equation, and the nonlinear compaction equation considering the friction effect was established and validated to characterize the powder compaction mechanisms under different die wall friction. With the friction coefficient increased, the relative fractional contributions of the particle rearrangement mechanisms increased and the powder deformation mechanisms contributions decreased. Finally, the influences of die wall friction on powder compaction behaviors were discussed. The results shown that the die wall friction significantly influence the powder flow behaviors and residual elasticity, which induce inhomogeneous relative density and stress distribution, cracks and capping in powder compact.