Failure Mechanisms and Interphase Chemistry of Gold Films on Ti6Al4V. Part II. Etching of Ti6Al4V and its Effect on Evaporated Gold and Commercial Adhesive Adhesion

摘要

This work is part of a program which looks at the effects of surface treatments on surface chemistry and morphology of titanium alloys with reference to adhesive bonding. Here gold is vapor deposited on Ti6Al4V which was prepared to simulate conditions of etching and aging which might be encountered during processing and use. Although this model system of gold on Ti6Al4V is not a direct analogy to adhesive bonding, certain similarities do exist and the system provides interesting information on bond failure mechanisms. Surface chemistry changes suggest selective etching of the alpha phase and subsequently larger influence of the alpha phase in bonding. Heating of the gold on Ti6Al4V resulted in improved adhesion, probably by diffusion mechanisms. Exposure to steam resulted in bond degradation in both gold/Ti6Al4V and in adhesive/Ti6Al4V systems. The adhesive bonding results for the etched specimens were compared to expected performance based on 'attachment site' theory. Excellent agreement for both gold on Ti6Al4V and commercial adhesive on Ti6Al4V was observed. Degradation of the bond due to steam followed the same form in both systems.