The effect of sintering modes on the crystal lattice parameters and the morphology of the ZrO2–nY2O3 (n = 3–8 mol%) ceramic microstructure components

Abstract

The purpose of this work is to study the effect of sintering modes, especially the sintering temperature, on the crystal lattice parameters and the morphology of the ZrO2–nY2O3 (n = 3–8 mol%) ceramic microstructure components in relation to corresponding fracture micromechanisms.The series of ZrO2–nY2O3 (n = 3–8 mol%) ceramics were sintered in an argon atmosphere at temperatures 1450C, 1500C, 1550C, and 1600C. The cross-sectional surfaces of samples were prepared for microstructure analysis using a grinding and polishing Struers Tegramin machine. Young’s ceramics modulus values were determined using an ultrasonic flaw detector Panametrics EPOCH III 2300. The samples’ density and porosity were determined by the Archimedes’ method. Scanning electron microscopes Hitachi SU3900 and Carl Zeiss EVO-40XVP were used to analyse the microstructure and fracture surface morphology of samples. For estimating chemical compositions in an energy-dispersive X-ray spectroscopy mode, an INCA ENERGY 350 spectrometer was utilized. Microhardness measurement was performed on a NOVOTEST TC-MKB1 microhardness tester. The fracture toughness of the material was estimated using a single-edge notch beam (SENB) test and the Vickers indentation test. Both the flexural strength and SENB tests were performed under three-point bending using a UIT STM 050 test machine. All mechanical tests were carried out in air at a temperature of 20C.Optimal sintering modes for a variety of YSZ ceramic compositions are found, taking into account the combined effect of the sintering temperature and a percentage of Y2O3, which resulted in a specified balance of cubic, tetragonal, and monoclinic zirconia phases, an optimal microstructure features, and the implementation of high-energy fracture micromechanisms responsible for high strength and fracture toughness of YSZ ceramics.To study the behaviour of YSZ ceramics in the operating atmosphere, their microhardness, flexural strength, and fracture toughness should be evaluated under the operating temperature and pressure conditions.Based on the research performed, it is possible to design the microstructure of YSZ ceramic with the necessary physical and mechanical properties to provide high reliability of ceramic products in various industry branches.The balance of cubic, tetragonal, and monoclinic zirconia phases, as well as the crystal lattice parameters change, was determined for YSZ ceramics stabilized with the various amounts of yttria, and it was linked to their mechanical behaviour; the Vickers indentation method and SENB method were used to estimate crack growth resistance of YSZ ceramics, and an appropriate fracture micromechanism was found.