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Hall-Petch Theory and Inverse Hall-Petch Theory addressed the relation of grain size and mechanical properties for a material. Both theories explained an opposite effect of grain size toward the strength of the material. 3Y-TZP exhibited both the Hall-Petch Theory and Inverse Hall-Petch Theory, and the effects were distinguished by critical grain size value. The "Pre" and "Post" critical value showed Hall-Petch effect and Inverse effect respectively. This is causing the limitation on the processing of 3Y-TZP, for every processing requires to determine the critical value to understand mechanical behavior of the material. With the sintering aides, CuO, the phenomenon was greatly reduced and minimized. Without the coexisting of both mentioned effects, the processing and application of doped-3Y-TZP will be extended without iteratively experimental work to determine the critical value. [ABSTRACT FROM AUTHOR]

Indentation Fracture (IF) Method is commonly used to determine the fracture toughness of ceramic materials. However, different researchers, such as Evans and Charles, Niihara et al., B.R Lawn et al., Anstis et al., and Shetty et al., had proposed the respective analysis models, but and all the analysis are related to the parameters like cracking length (c) and indent length (2a). The ratio of c/a is used to differentiate between Palmqvist and Median (half-penny) cracking profiles during fracture toughness evaluation. In this study, three analysis models, including the Evans and Charles et al. (EC model), Shetty et al. (Shetty Model), and Evans and Wilshaw et al. (EW Model) models, were used to evaluate the fracture toughness of 3Y-TZP and CuO-doped 3Y-TZP while following the rule that c/a ≤ 2.5 indicates a Palmqvist cracking profile. The results were compared and verified, and it was found that the EC model and Shetty model displayed consistent output result of fracture toughness the mentioned materials. Based on two analysis models, the evaluation also revealed that the optimal fracture toughness can be achieved by doping CuO at ≤ 0.2 wt.% and using conventional sintering methods at sintering temperatures below 1400°C. [ABSTRACT FROM AUTHOR]

Grain growth is one of the main factors to determine the materials properties of yttria stabilized zirconia. The objective of the study is to reveal the effect of grain growth kinetics towards the phase transformation and the phase stability of CuO doped 3Y-TZP with various amount of the dopant by using conventional sintering in the temperature range between 1250°C to 1500°C. The result showed 0.2 wt.% dopant gave the most optimum phase stability without compromising the stress transformation induction of the material. X-Ray diffraction (XRD) result showed the effect of sintering temperature, amount of dopant towards the phase transformation. Through analysis by using the plot of Arrhenius, 0.2 wt.% possessed the highest and 1.0 wt.% had the lowest activation energy. Based on Lange's thermodynamic equation, a framework of the relation between tetragonal phase stability and transformation barrier of all the samples is presented. [ABSTRACT FROM AUTHOR]