The Effect of Sintering Temperature on Crack Growth Resistance Characteristics of Fine-Grained Partially Stabilized Zirconia Determined by Various Test Methods

Abstract

Zirconium oxide (zirconia) is widely used as a structural material in various applications. However, upon heating, zirconia undergoes disruptive phase changes. By adding small percentages of yttria, these phase changes are eliminated, and the resulting yttria-stabilized zirconia material has superior thermal, mechanical, and electrical properties. The transformation toughening mechanisms allow getting higher strength and crack growth resistance of such ceramics. In this work, yttria-stabilized zirconia ceramics sintered at various temperatures have been studied. The series of beam specimens of ZrO2 ceramics partially stabilized with 3, 4, and 5 mol% Y2O3 were prepared using a conventional sintering technique. Three sintering temperatures were used for each series: 1450 °C, 1500 °C, and 1550 °C. Two different mechanical tests were performed: single-edge notch beam test under three-point bending and fracture toughness test by indentation method. In both cases, fracture toughness was calculated using obtained experimental data. Based on the constructed dependences of fracture toughness on sintering temperature for the specimen series, it was revealed that both the yttria percentage and sintering temperature affect the mechanical behavior of the ceramics. The maximum transformation toughening effect was revealed for ZrO2–5 mol% Y2O3 ceramics. Based on the studies of fracture surface images and X-ray diffraction analysis, it was concluded that transformation toughening of such ceramics is accompanied by distinct changes in the fracture surface morphology.