Microstructural effects on the sliding-wear resistance of ZrC-MoSi2 triboceramics fabricated by spark-plasma sintering

The effects were individually investigated of ZrC grain size and MoSi2 content on the lubricated sliding wear resistance of ZrC-MoSi2 triboceramics densified by spark-plasma sintering (SPS). Microstructures with different average grain sizes were obtained by varying the high-energy ball-milling time of the ZrC-MoSi2 powder mixtures and their SPS temperature, while the microstructures with different secondary phase contents were obtained by varying the relative concentrations of ZrC and MoSi2 in the powder batches. Experimentally, it was found that the ZrC-MoSi2 triboceramics are all highly wear resistant, but also that wear resistance decreases as the ZrC grain size and MoSi2 content increase. The dominant wear mode was identified as abrasion, and the prevailing wear mechanism was plastic deformation accompanied by localized fracture. Accordingly, the wear trends are explained in terms of the hardness of the ZrC-MoSi2 triboceramics. Finally, the implications are discussed of providing the electrically-conductive ZrC-MoSi2 triboceramics with greater wear resistance via controlled processing. (C) 2016 Elsevier Ltd. All rights reserved.