Unveiling wear mechanisms of tantalum carbide-silicon carbide composites: Influence of silicon carbide content and sliding load

Tantalum carbide (TaC), as ceramic coating, is known for its exceptional wear performance, however, the tribological behavior of bulk TaC ceramics is poorly understood and requires persistent research. In the current study, the tribology of spark plasma sintered TaC-SiC composites in dry sliding contacts against silicon carbide (SiC) counterbody under various sliding loads (5, 10, and 15 N) is investigated with respect to change in SiC content (from 0 to 65 vol%). With changes in reinforcement content and load, the coefficient of friction and wear rate varied in the range of 0.25-0.45 and 4.7 x 10-7-2.1 x 10-6 mm3/Nm, respectively. At 5 N load, dominant abrasion is observed for composites containing SiC content up to 35 vol%, while abrasion and mild fracture are observed for the composites containing above 35 vol% SiC. At 15 N load, abrasion and oxidation are observed on worn surfaces of monolithic TaC. TaC composites with <= 35 vol% SiC content exhibited abrasion, pull-outs, and tribo-oxidation, while composites with >= 50 vol% SiC content experienced severe fracture along with tribo-oxidation. The presence of tribo-oxidation on worn tracks at a higher sliding load (15 N) is confirmed by X-ray photoelectron spectroscopy results.