Computational modeling and mechanical properties of 3Y-TZP ceramic composites reinforced by mullite whiskers with different diameters

Abstract

An accurate characterization of microstructure is essential to realize the performance prediction and design optimization of the ceramic matrix composites (CMCs). In this work, according to the feature of in-situ growth of mullite whiskers in 3 mol% Y2O3 stabilized tetragonal ZrO2 (3Y-TZP) ceramics, 2 vol% whiskers of different diameters formed in the 3Y-TZP ceramics were numerically reconstructed based on Monte Carlo method to explore the mechanical properties of the ceramic composites. The results show that the nanoindentation model of whisker reinforced 3Y-TZP ceramics can effectively predict the hardness of the composite ceramics according to load-depth curves. The stress transfer mechanism between the ceramic matrix and the whiskers can also be found. It is found that the hardness of the composite ceramics decreases gradually with the increase of the whisker diameters. According to three-point bending model, the obtained bending strength and fracture toughness of the composite ceramics increase first and then decrease with increasing whisker diameter. When the diameter of mullite whiskers is 0.12 μm, the bending strength of the composite ceramics reaches the maximum of 826 ± 25 MPa and the fracture toughness reaches the maximum of 10.5 ± 0.2 MPa•m1/2. The toughening mechanism of whisker reinforced 3Y-TZP ceramics was also demonstrated. This work provides a numerical method for the selection and optimization of parameters of reinforcement phase in preparation of 3Y-TZP ceramic composites.