Influence of surface treatment on interfacial microstructure and bond strength of diffusion-bonded tin

An investigation has been made of the bond strength of solid-state diffusion-bonded interfaces of tin specimens whose faying surfaces were finished through four different treatments: grinding on abrasive paper of 800 grade, electrolytic polishing in a solution of perchloric acid in ethyl glycol monobutyl and ethanol, halogenation by HCl vapor, and halogenation by HF vapor. The bond strength of the joint was increased with a rise in bonding temperature for all the surface treatments. The grinding on abrasive paper required the highest bonding temperature to obtain the bond strength comparable with the base metal, followed by the electrolytic polishing, halogenation by HCl, and halogenation by HF. These effects of the surface treatments on the bond strength were discussed on the basis of TEM observations of the behavior of interfacial inclusions that were identified as tin oxide and tin oxide halide (for the halogenation treatments) based on SAD and EDX analyses.