Enhanced densification of TaC coating on graphite substrate via cobalt-assisted liquid phase sintering using wet powder process

• Introduced a method for fabricating dense TaC coatings using Co as a sintering aid. • Investigated the effects of Co content and sintering temperature on TaC coatings. • Cobalt addition enhanced the density and mechanical properties of coatings. • Proposed a densification mechanism for the sintering process of TaC coatings. In this work, tantalum carbide (TaC) coatings were prepared on graphite substrates using a wet powder forming and sintering process with the addition of cobalt (Co) as a sintering aid. The effects of cobalt content on the densification, phase composition, microstructure, and mechanical properties of the TaC coatings were investigated. The addition of a small amount of Co promoted the densification of the coating and enhanced its hardness and elastic modulus. At a Co content of 1.5 wt%, the coating exhibited a relative density of approximately 95.7 %, a hardness of 18.1 GPa, and an elastic modulus of 395.0 GPa. Morphological analysis revealed the densification mechanism of the coating during the high-temperature sintering process. Under the influence of the Co liquid phase, TaC particles rearranged and underwent dissolution-precipitation in the liquid phase, ultimately achieving densification of the coating.