Synthesis, microstructural characterization, and mechanical property evaluation of vacuum plasma sprayed tantalum carbide

Tantalum carbide (TaC) is an ultra-high-temperature ceramic for potential applications as protective coating, furnace components, propulsion liners for space shuttles and aircrafts, etc. Microstructural and mechanical behavior of vacuum plasma-sprayed (VPS) TaC has been investigated in the present study. Apart from major TaC phase, microstructural definitions elucidated Ta2C, non-stoichiometric TaCx phases (0.83 <= x <= 0.94), partial grain formation, polygonization of grains, and inhomogeneous C/Ta ratios in the sprayed structure. Near-isotropy in the fracture-toughness ratio (K-axial/K-trans=1.01) is attributed to compact coating, fine-closed porosity, and distribution of non-stoichiometric phases.