Physico-chemical nanomaterials science

The effect of rare-earth metal oxide additives on crack growth resistance of fine-grained partially stabilized zirconia
Kulyk V.V.1, Duriagina Z.A.1,2, Vasyliv B.D.3, Vavrukh V.I.1, Kovbasiuk T.M.1, Lyutyy P.Ya.1, Vira V.V.4
1 Department of Materials Science and Engineering, Lviv Polytechnic National University, 12 S.Bandera str., Lviv 79000, Ukraine.
E-mail: kulykvolodymyrvolodymyrovych@gmail.com
2 Department of Materials Engineering, The John Paul II Catholic University of Lublin, 14 Racławickie Al., Lublin 20-950, Poland.
3 Department of Hydrogen Technologies and Alternative Energy Materials, Karpenko Physico-Mechanical Institute of the NAS of Ukraine, 5 Naukova str., Lviv 79060, Ukraine.
4 Department of Strength of Materials and Structural Mechanics, Lviv Polytechnic National University, 12 S.Bandera str., Lviv 79000, Ukraine.

Recently, the additives of rare-earth metal oxides are being used for obtaining partially stabilized zirconia ceramics aimed at applications in various high-temperature structural components. Corresponding sintering modes providing fine-grained microstructure formation are being developed. Due to the obtained correlations between the morphology parameters and resulting mechanical characteristics of ceramics it is possible to reach a unique combination of their functional properties.
In this work, zirconia ceramics stabilized with small percentages of rare-earth metal oxides have been studied in terms of sintering ability, elimination of the phase changes in zirconia, as well as employment of the transformation toughening mechanism during crack propagation. The metal oxides including rare-earth metal oxides (Y2O3, CoO, CeO2, Fe2O3) were used as additives to reach a stabilizing effect on zirconia and manufacture ceramics with fine-grained microstructure. Series of ceramic specimens were prepared using conventional sintering in a temperature range of 1500 °C to 1850 °C with and without annealing. Fracture toughness test by indentation method and single-edge notch beam test under three-point bending were performed. Based on X-ray diffraction analysis and SEM studies of fracture surfaces of specimens it was concluded that the maximum transformation toughening effect revealed for ZrO2–Y2O3–CoO–CeO2–Fe2O3 ceramics was related to a distinct change in the fracture surface pattern.