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The purpose of this research is focused on the manufacture and characterization of a partially stabilized zirconia ceramic with 3 mol% of Yttria and doped with.5 and 1.5 mol% of Nb2O5 to analyze the influence of doping, with the purpose of improving the properties before hydrothermal degradation. In the first instance, the microwave sintering process was used for the consolidation of this material, then the physical and mechanical properties were characterized. Together, the results obtained by the conventional sintering process were compared. A low hydrothermal degradation study (LTD) is presented at low temperatures in which possible changes in the mechanical properties of the ceramic materials are analyzed and its influence on the phase transformation that zirconia may present is observed. The mechanical properties were evaluated through hardness, fracture toughness, and Young's modulus tests. Likewise, their density was analyzed, and microstructure was characterized by FESEM. It was found that the microwave‐sintered samples at 1200°C exhibited superior properties of toughness than even samples sintered by conventional methods at higher temperatures (1400°C). The sample of 3Y‐TZP with 1.5 mol% Nb2O5 sintered by microwave with <.2% of porosity achieved a maximum fracture toughness value around 40% higher than the dense monolithic 3Y‐TZP material. [ABSTRACT FROM AUTHOR]

The aim of this work is to study the physical, chemical, and mechanical properties of 3 mol% Yttria-stabilized Tetragonal Zirconia Polycrystalline (3Y-TZP) materials doped with varying amounts of iron oxide (0, 400, 800, and 1000 ppm). We carried out full dense consolidation using two different sintering methods: fast-microwave technology at 1200°C and 1300°C, and conventional furnace at 1400°C. It was observed an improvement in density and hardness values, as well as great fracture toughness, and more intense color was achieved resulting in more natural color, similar to that of human teeth, using the microwave technique at 1300°C compared to the conventional method. However, the microwave-sintered specimens exhibited an increase in zirconia grains size and high color intensity along with iron oxide content when compared to conventional process, where the grain size does not vary with the coloring agent content. The results obtained in this work suggest that microwave technology can produce an increase in sintering activity due to the different dielectric properties of 3Y-TZP materials doped with Fe2O3. Another interesting confirmed result is that the addition of Fe2O3 presents a high resistance to low temperature hydrothermal degradation producing a delay in the aging process. [ABSTRACT FROM AUTHOR]

Lithium aluminosilicate was fabricated by conventional and nonconventional sintering: microwave and spark plasma sintering, from 1200 to 1300°C. A considerable difference in densification, microstructure, coefficient of thermal expansion behavior and hardness and Young's modulus was observed. Microwave technology made possible to obtain fully dense glass-free lithium aluminosilicate bulk material (>99%) with near-zero and controlled coefficient of thermal expansion and relatively high mechanical properties (7.1 GPa of hardness and 110 GPa of Young's modulus) compared with the other two processes. It is believed that the heating mode and effective particle packing by microwave sintering are responsible to improve these properties. [ABSTRACT FROM AUTHOR]

Commercially, 3 mol% Y2O3-stabilized tetragonal zirconia (70-90 nm) compacts were fabricated using a conventional and a nonconventional sintering technique; microwave heating in a resonant mono-mode cavity at 2.45 GHz, at temperatures in the 1100-1400°C range. A considerable difference in the densification behavior between conventional ( CS) and microwave ( MW) sintered materials was observed. The MW materials attain a full density of 99.9% of the theoretical density (t.d.) at 1400°C/10 min, whereas the CS reach only 98.0% t.d. at the same temperature and 1 h of dwelling time. Therefore, the MW materials exhibit superior Vickers hardness values (16.0 GPa) when compared with CS (13.4 GPa). [ABSTRACT FROM AUTHOR]