Wave mode high voltage consolidation of powder materials

Abstract The densification of electrically conductive powders by high voltage consolidation is studied. High voltage consolidation method (HVC) includes the simultaneous exposure of a powder sample to mechanical pressure (50–500 MPa) and to a short (less than 300 ms) high voltage (above 1 kV) electric discharge with the pulse current amplitude of a few hundred kA/cm 2 . The densification kinetics of industrial iron powder is analyzed by ultra-rapid video-recording. The integral temperature of the sample has a maximum value at the beginning of the densification process. The compaction process lasts less than 16 ms for all the values of the parameters studied. The shortness of the densification process in comparison with the cooling of the sample provides a constant temperature throughout the entire compaction process. Based on the analysis of the obtained experimental results a mathematical model of high rate wave mode compaction of a powder material under conditions of HVC is formulated. The constitutive equation of the mechanical behavior of the consolidated material accounts for the plastic flow of powder particles and for the collapse of the inter-particle pores. The numerical simulation results reveal optimal values of the dimensionless parameters controlling the HVC process.