Consolidation of TiAl Powder by Thermal Spray Processes

Thermal spray deposition has been widely used as a coating process for applying thin protective layers to the need-to-protect materials, or substrates. Recent technological developments in thermal spray processing, particularly cold gas spraying (CGS) and supersonic plasma spraying (S-PS), have enabled some emerging applications for making structural components. This paper reports on the results of our recent attempts to obtain thick TiAl coatings using three coating techniques: atmospheric plasma spraying (APS), S-PS and CGS. We successfully achieved a 3 mm thick coating using both APS and S-PS techniques, but failed in cold spray. A significant phase change was observed of the powder particles experienced during both APS and S-PS processes. Nevertheless, a considerable quantity of titanium oxides was observed in the APS coating.