The influence of spark plasma sintering parameters on the microstructure, physical, and mechanical properties of ZrO2–3 mol% Y2O3 ceramics

<ns3:p>The purpose of the work is to study the effect of the SPS sintering temperature on the transformation of the phase composition, microstructure, and the set of physical and mechanical properties of ZrO2–3 mol% Y2O3 ceramics.Yttria-stabilised zirconia ceramic samples of the ZrO2–3 mol% Y2O3 composition (3YSZ) were fabricated from corresponding powder by spark plasma sintering (SPS) at temperatures of 1150–1350C under a constant pressure of 63 MPa with a holding time of 4 min. The sample density and porosity were estimated by Archimedes’ method. The elastic moduli of the ceramics were determined using a Panametrics EPOCH III ultrasonic tester. Microhardness of the ceramics was determined by the Vickers indentation method using a NOVOTEST TC-MKB1 microhardness tester. The fracture toughness of the ceramics was estimated by the single-edge notched beam (SENB) and the Vickers indentation test methods. A UIT STM 050 test machine with a self-made three-point bending test unit was used for the determination of the SENB fracture toughness and flexural strength of the ceramics. All mechanical tests were performed in air at 20C. A Malvern Panalytical X-ray diffractometer (XRD) was used for XRD analysis. Scanning electron microscopes, Hitachi SU3900 and Thermo Scientific Apreo 2C, were used to analyse the microstructure and fracture surface morphology of the samples.It is shown that 3YSZ ceramics sintered at 1200C have the optimal phase composition and morphology of the individual microstructure components, which provides the highest crack growth resistance. Due to the differences in the microstructure of ceramics manufactured by the high-speed spark plasma sintering method, it is recommended to use traditional methods of fracture mechanics, along with the indentation method, to determine their fracture toughness accurately.The operating atmosphere, temperature, and pressure are the crucial parameters for the ceramic products. It requires estimating the microhardness, flexural strength, and fracture toughness of the ceramics under such conditions.The research results enable the design of the microstructure of 3YSZ ceramics through SPS sintering, providing high reliability of ceramic products across various industrial branches by achieving the necessary physical and mechanical properties.The balance of tetragonal and monoclinic zirconia phases and microstructure of the 3YSZ ceramics sintered by SPS at various temperatures were evaluated and linked to the mechanical behaviour of the ceramics; the SENB and Vickers indentation methods were applied to estimate crack growth resistance of 3YSZ ceramics, and a high-energy consuming fracture micromechanism corresponding to the appropriate sintering mode was found.</ns3:p>