Bonding Test for Tungsten Plates by Pulse Discharge Sintering Method

Abstract

Bonding experiment has been performed for tungsten plates with the Pulse Discharge Sintering (PDS) method. The bonded interfaces have been evaluated by observing the optical microstructure and ultrasonic imaging, and the effect of bonding condition on the bending strength of the bonded samples was examined. For the samples bonded without insert material in between the tungsten component plates, evidence of grain growth across the bonded interface was observed, indicating the occurrence of diffusion bonding. Many pores have been found at the interface of the bonded sample when tungsten powder was used as insert material, whereas pores were not observed for the sample bonded with tantalum powder as insert material. The bending strength of the samples bonded with tantalum and tungsten powder as insert materials, and that bonded without insert material has been measured to be about 400, 200 and 100 MPa, respectively. The bonded sample with tantalum has been found to possess a higher bending strength than that of the tungsten component plate. It has been demonstrated that a longer activating pulse discharge time in the PDS process leads to a higher bending strength for both samples bonded with tungsten powder and without insert material.