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

This work was aimed at reporting a new method for fabrication of TaSi 2 coating. In this research, vacuum plasma spray (VPS) process was applied to fabricate TaSi 2 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 TaSi 2 coating was composed of hexagonal TaSi 2 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 TaSi 2 coating was completely oxidized and fragmented into pieces after oxidation at 900 °C for 1 h. The oxidation mechanism was also discussed. [ABSTRACT FROM AUTHOR]