Exploring High-Velocity Air-Fuel and Cold Spray Deposition of Ti6Al4V for Repair Applications

The aerospace industry is increasingly seeking to adopt novel approaches to reduce weight of aircraft and improve engine efficiency by employing lighter materials like titanium alloys, bimetallics and composites. However, when damaged, the replacement of these parts is costly. Additionally, repair of these materials is not straightforward as traditional repair methods involving high temperature processing like electron beam patch welding, high velocity oxy fuel spraying, and plasma spraying can be detrimental to the substrate as well as the built-up materials. Therefore, there is a significant interest in exploring alternative low heat input repair technologies such as high velocity air fuel spray (HVAF) and cold spray (CS), particularly for repair of components manufactured from temperature-sensitive materials like Ti6Al4V. This paper investigates the influence of HVAF and CS process variables on the porosity, microstructure, oxygen pickup, microhardness, and wear of as-processed Ti6Al4V coatings. In addition, the coatings are heat treated and hot isostatically pressed post-deposition between 800-1050°C to understand the influence of heat treatment and hot isostatic pressing on the coating characteristics. It is expected that the results of this study would illuminate the appropriate repair process for Ti6Al4V parts.