Diffusion bonding of dissimilar materials for space applications via hot isostatic pressing

In this work, hot isostatic pressing diffusion bonding (HIP DB) behaviour of dissimilar materials such as niobium (Nb), platinum (Pt) and titanium alloy (Ti6Al4V) were assessed, especially for thrust combustion chamber used in rocket engines. In particular, the development of an oxidation-resistant layer for pure Nb using Pt was addressed. The diffusion layer analysed by scanning electron microscopy (SEM) shows a successful reaction between pure Nb and Pt with the generation of a 20 µm thick, fully dense reaction layer. Furthermore, the DB of pure Nb with Ti6Al4V was also investigated to evaluate the possibility of joining Nb and Ti6Al4V dissimilar materials for space applications. HIP-DBtrials presented in this work demonstrate the possibility of replacing the conventional R-512 E di-silicide coating with a Pt layer and the fusion welding of Nb and Ti6Al4V with solid state HIP-DBjoining to obtain a defect-free joint with a desirable microstructure at or near the interface.