Nanoindentation and tribology of VC, NbC and ZrC refractory carbides

Deformation, damage and wear characteristics of spark plasma sintered VC, NbC and ZrC refractory carbides have been investigated using nanoindentation, tribology and micro/macro − indentation tests. Fractography, using SEM, AFM and confocal microscopy, was used for the characterization of deformation and damage mechanisms. Considerable indentation load − size effect was found in all systems with hardness values from 30 to 36 GPa to 13-17 GPa corresponding to the applied loads of 1 mN and 100 N, respectively. During nanoindentation, characteristic stress-drops were observed on hardness-displacement profiles of NbC and ZrC at depth region of 15-30 nm while this was not typical in VC. The highest coefficient of friction was measured for NbC with a value of 0.45 and the lowest for ZrC with an average value of 0.3. The wear rate of the NbC, and VC was similar, approximately 3 × 10−6 mm3/Nm only the wear rate of ZrC was larger, approximately 2 × 10−5 mm3/Nm.