Tribological properties of TiB2 and TiB2–MoSi2 ceramic composites

Recently, dense monolithic TiB₂ and TiB₂–20 wt.% MoSi₂ composites with high hardness (24–26 GPa) have been processed by hot pressing. To assess the tribological potential, the present study was performed in analyzing the influence of load on the fretting wear of TiB₂ and TiB₂–MoSi₂ composites against bearing steel. Under the investigated conditions, a higher coefficient of friction (COF) of 0.5–0.6 was recorded with all the materials with a lower COF at a higher load of 10 N. Detailed microstructural investigation of the worn surfaces was carried out using SEM–EDS and XRD in order to understand the fretting wear mechanisms. Severe wear (order of 10⁻⁵ mm³/N m) was measured for the investigated materials under the selected fretting conditions with lower wear rate for TiB₂–20 wt.% MoSi₂ composite at all loads (2–10 N). While abrasive wear dominates the material removal process in the case of monolithic TiB₂, the tribochemical wear is observed to be the predominant wear mechanism for the composite.