Microstructure and thermal stability of TaSi2 coating fabricated by vacuum plasma spray

This work was aimed at reporting a new method for fabrication of TaSi2 coating. In this research, vacuum plasma spray (VPS) process was applied to fabricate TaSi2 coating. The chemical composition and microstructure of the coating was characterized by SEM, XRD, TEM and EDS. Its thermal stability was evaluated by TG-DTA and oxidation tests at 500 °C-1000 °C. The results showed that the TaSi2 coating was composed of hexagonal TaSi2 phase and presented dense lamellar microstructure combining defects, such as pores, interfaces and oxygen impurity. There was a sharp weight increase in TG curve at range of 800 °C-1000 °C with an exothermic phenomenon. The coating exhibited excellent thermal stability at 500 °C up to 50 h in atmospheric environment. Obvious oxidation was observed at 800 °C. The TaSi2 coating was completely oxidized and fragmented into pieces after oxidation at 900 °C for 1 h. The oxidation mechanism was also discussed.