Material Properties and Tribological Behavior of Copper-Doped Zirconia Ceramics for Dental Applications

The effect of Cu content on the properties of hot-press sintered zirconia was systematically evaluated. ZrO2 was fabricated with varying Cu concentrations, and its density, hardness, strength, and toughness were characterised. Tribological analysis was performed using ball-on-disk testing, and wear and fracture were examined microscopically. The results indicated a clear dependency of material properties and tribological behaviour on copper content. The density, hardness, and flexural strength exhibited a gradual decline with increasing copper concentration. Although fracture toughness decreased initially with up to 5% Cu doping, an unprecedented increase at higher concentrations (≥10%) was observed, which was attributed to stress concentration from pore defects that altered crack propagation paths. Tribologically, samples with ≤5% Cu maintained a stable coefficient of friction and low wear rate. In contrast, a higher Cu content (≥10%) caused an increased wear rate due to microstructural deterioration featuring large, porous grains. However, the debris from this wear process filled the surface pores, subsequently reducing the friction coefficient. The predominant wear mechanism identified was abrasive wear. The suitable content (10%) of Cu maintains adequate mechanical strength and wear resistance for dental restorative applications.