Abstract
The effects of CeO2 addition on the sintering behavior and mechanical properties of Y-TZP have been investigated over a wide sintering regime by pressureless sintering. It has been revealed that small additions of CeO2 (0.3–1.0 wt%) to Y-TZP were beneficial in enhancing the mechanical properties and hydrothermal ageing resistance of Y-TZP. Sintered samples were used to evaluate the bulk density, Vickers's hardness, Young's modulus, and fracture toughness of the material. CeO2 doped Y-TZPs were sintered at relatively low temperatures (1250°C and 1350°C) retaining high bulk density (>97% of theoretical density) and high Young's modulus (>200 GPa) without sacrificing tetragonal phase stability. The optimum level of dopant was found to be at 0.5 wt% for sintering between 1250°C and 1450°C using the standard 2 h holding time cycle, with sintered body exhibiting excellent combination of properties when compared to the undoped ceramics. In this experiment, the addition of 0.5 wt% recorded a bulk density reading of 5.9 g/cm3, Vickers hardness value of 13.2 GPa, Young's modulus value of 211 GPa, and fracture toughness of 6.4 MPam1/2, respectively, in a temperature range of 1400–1450°C.
Highlights
Yttria tetragonal zirconia polycrystal (Y-TZP) ceramics serve as an upcoming material for engineering applications and are considered important for restoration medicine
The findings revealed that the ceramic can suffer a slow, tetragonal to monoclinic phase transformation at the samples surface in a humid atmosphere, followed by microcracking and a major loss in strength known as low temperature degradation (LTD) [6,7,8,9,10]
Two commercial type powders were prepared for this experiment: the 3 mol% of yttria-stabilized zirconia powder manufactured by Kyoritsu Ltd., Japan, under the code name of KZ-3YF as the base powder and cerium oxide, CeO2, manufactured by Sigma Aldrich, as the dopant
Summary
Yttria tetragonal zirconia polycrystal (Y-TZP) ceramics serve as an upcoming material for engineering applications and are considered important for restoration medicine. The stabilizing effect of yttria (Y2O3) makes it possible for Y-TZP ceramic to be processed in the metastable tetragonal (t) structure This is essential since the retention of the (t) phase at ambient temperature allows it to transform to the monoclinic (m) structure under external applied stress [3, 4]. The findings revealed that the ceramic can suffer a slow, tetragonal to monoclinic phase transformation at the samples surface in a humid atmosphere, followed by microcracking and a major loss in strength known as low temperature degradation (LTD) [6,7,8,9,10]. CeO2 is generally used to stabilize the tetragonal phase of zirconia and is known to increase the sintering of glass ceramics and strength and thermal stability [25]. The average grain intercept method is used to measure the grain size of a material by drawing randomly positioned line segments on the micrograph, counting the number of times each line segment intersects a grain boundary, and finding the ratio of intercepts to line length
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