Influences of evaluation methods and testing load on microhardness and Youngʹs modulus of ZTA and ATZ ceramics

In this work, microindentation tests under different conditions were performed to determine the influence of indentation load on Youngʹs modulus and microhardness of ZrO2 reinforced with Al2O3 particles (ATZ) and Al2O3 reinforced with ZrO2 particles (ZTA). Microhardness of ATZ and ZTA materials was measured using traditional Vickers and instrumented microhardness methods at 500, 1000, 1500 and 2000 mN loads. As for the instrumented method, Vickers microhardness was calculated from the force-indentation depth curves by analyzing the unloading segments, according to the Oliver–Pharr method. In this way the possible differences between the two methods were calculated. Furthermore, Youngʹs modulus at each load was calculated using the instrumental method. The main differences between the two methods were analyzed, and the influence of the load on the definition of Youngʹs modulus in the case of the instrumental method was studied. The results indicated an indentation load effect for both materials, as hardness and Youngʹs modulus increase by decreasing the indentation load.