JOINING OF DISSIMILAR MATERIAL (SS-Cu) USING DIFFUSION BONDING TECHNOLOGY

Abstract

Diffusion bonding technologies have been widely used for joining several similar and dissimilar metal systems in which the main mechanism is inter diffusion across the faying surface. Diffusion bonding technology has been extremely helpful where other joining processes cannot be used for some characteristic reasons or materials property. The main reason for extending the technology is the growing necessity of improvement and enhanced performance of the materials. In this report the attempts are made to study the effects of parameters on the diffusion bonding of the metal system (Stainless steel-Copper). Report begins with the definition of diffusion bonding, the explanation of the process and parameters. After finding the diffusion bonding feasible between stainless steel and copper, research work continued with two different studies (a) studying the effect of change in maximum pressure in constant pressure study (b) studying the effect of change in number of pressure pulses in impulse assisted pressure diffusion bonding. Preparation of the surface is very critical in case of diffusion bonding. Therefore all the samples were polished in two stages rough polishing and fine polishing as any oxides or impurity present offers hindrance to diffusion across the surface. Process was accomplished in hot vaccum press under protected temperature. Microstructure, metallographic and mechanical properties of the samples was studied to find out the effect of parameters used. Optimum parameters were found to be 4 MPa, 875˚C, 30 minutes in constant pressure diffusion bonding. Maximum strength of 226.653 MPa was obtained at this set of parameters. In impulse assisted diffusion process, maximum strength (223.093 MPa) was found at 20 pressure pulses keeping all other parameters constant (6 MPa, 875˚C, 30 minutes).