Micro-Macro Analysis of Capacitor Discharge Sintering in Copper-Diamond Bead

Capacitor Discharge Sintering (CDS) is an ultrafast electric current assisted sintering method (ECAS) suited for electrically conductive metallic and metal-ceramic composite powders. The technique is a solid state near net shape sintering process which is in general characterized by a very short discharge time (tens of milliseconds), very high current intensity peak (up to 350 kA) and relatively high pressure (up to 1 GPa) with minimum shrinkage. Computer modeling comes to aid in the setup of industrial processes to produce enhanced sintered products such as copper–diamond beads for stone cutting applications. The simulation of the CDS process introduces a new class of nonlinear problems, involving a complex bulk and contact multiphysics with an intricate coupling of micro–macro phenomena. The work presents a micro–macro CDS model along with the solution strategy developed to assess the densification behavior of a copper–diamond bead for stone cutting applications. The overall CDS model implements a four-way coupling strategy which combines the relevant partial differential equations governing the electrical, thermal, and stress–strain fields over the macroscopic scale of the CDS system, with the densification kinetic model governing the particle scale phenomena. The results are presented in terms of field and shrinkage variables as a function of space and time.