* Technical contribution to the 2 nd International Brazilian Conference on Tribology – TriboBR 2014, November 3 rd to 5 th , 2014, Foz do Iguaçu, PR, Brazil. NIOBIUM CARBIDE (NbC) AS WEAR RESISTANT HARDMETAL IN OPENED AND CLOSED TRIBOSYSTEMS* Mathias Woydt 1 Hardy Mohrbacher 2 Abstract The tribological and mechanical properties of binderless and metal-bonded niobium carbides (8 or 12 vol.-% of Cobalt, 12 vol.-% of Fe3Al) are presented. Rotating disks made of niobium carbide bearing hard metals were mated against alumina (99.7%) under unlubricated (dry) unidirectional sliding tests (0,1 m/s to 12,0 m/s; 22°C and 400°C) as well as in oscillation tests (f= 20 Hz, x= 0,2 mm, 2/50/98% rel. humidity, n= 10 5 /10 6 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 8 m/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 high PV load carrying capacities. NbC-based hard metal bonded with 12 vol.-% of Fe3Al resulted in a higher hardness level than for 12 vol.-% 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. Keywords: Sliding; Friction; Wear; Ceramic; Oscillation; NbC; Niobium carbide; Cobalt; Fe3Al; Hard metal; Strength; Modulus; High temperatures. 1 Head of division 6.3 “Tribology&Wear Protection”, BAM Federal Institute for Materials Research and Testing, DE-12200 Berlin, Germany. 2 Managing director, Niobelcon BVBA, BE-2970 Schilde, Belgium. ISSN 2179-3956 190