The tribological and mechanical properties of niobium carbides (NbC) bonded with cobalt or Fe3Al

AbstractThe tribological and mechanical properties of niobium carbide bonded with 8vol.-% (NbC-8Co), 12vol.-% of cobalt (NbC-12Co) or 12vol.-% of Fe3Al (NbC-12Fe3Al) are presented. Rotating discs made of metal-bonded niobium carbide were mated against alumina (99.7%) under unlubricated (dry) unidirectional sliding tests (0.1m/s to 12.0m/s; 22°C and 400C) as well as in oscillation tests (f=20Hz, Δx=0.2mm, 2/50/98% rel. humidity, n=105/106 cycles). Microstructure and phase compositions were determined as well. The tribological data obtained were benchmarked with different ceramics, cermets, hard metals and thermally sprayed coatings, where NbC bonded with 8% and 12% Co presented above 7m/s the lowest wear rates so far in such a benchmark. Binderless NbC (HP-NbC1) and the metal-bonded NbCs exhibited low wear rates under dry sliding associated with P·V high load carrying capacities. NbC-based hard metal bonded with 12vol.-% of Fe3Al resulted in a higher hardness level than for 12vol.-% cobalt. The tribological profile established revealed a strong position of NbC-bearing materials under tribological considerations and for closed tribosystems against established reference tribo-couples