Fretting wear properties of sinter-HIPed ZrO2–ZrB2 composites

In view of the fact ceramic composites have an established niche in tribological applications, research efforts were invested in assessing and understanding the tribological properties of the recently developed ZrO2–30 vol.%ZrB2 composites against bearing steel. As part of the tribological investigation, fretting wear tests under varying load (2–10 N) were conducted on ZrO2 composites, presintered at 1400 °C in argon for 1 h followed by HIPing at 1400 °C under 110 MPa argon pressure for 1 h. Under the investigated fretting conditions, sinter-HIPed ZrO2 composites/steel couple exhibits higher COF of 0.5–0.8. At higher load of 10 N, lowest COF of 0.5 is commonly measured with all the tribocouples. The abrasion is commonly observed as the dominant wear mechanism in the investigated composites. However, the occurrence of transfer layer formation with occasional spalling is also noted. An important result of our research is that the wear rate decreases with increasing toughness and the sinter-HIPed ZrO2–ZrB2 composites exhibit lower wear rate (∼10−7–10−8 mm3/Nm) against steel.