Hydrothermal Degradation Behavior of Y-TZP Ceramics Sintered by Nonconventional Microwave Technology

Different factors such as the characteristics of starting powders, their processing, the sintering technique and the final sintering temperature were assessed with the goal to improve the low-temperature degradation (LTD) resistance of 3Y-TZP materials without compromising on the mechanical properties. The degradation of hydrothermally treated specimens was studied by AFM, nanoindentation technique, micro-Raman spectroscopy, and electron microscopy. 3Y-TZP previously prepared in laboratory by colloidal processing, and sintered by microwave method at low temperature (1200 degrees C) led to excellent mechanical and LTD resistance, as compared to dental restorations based on Y-TZP commercial material. In the former, the presence of m-phase was almost nonexistent even after 200 h of exposure to LTD conditions and the initial mechanical properties were maintained, giving 16 and 250 GPa mean values for hardness and Young's modulus, respectively. The influence of the fast-technology by microwave heating is presented with a nonconventional sintering method to fabricate 3Y-TZP ceramics for dental application with very high resistance against LTD and optimized mechanical properties.