1 School of Mechanical Engineering, Qinghai University, Xining 810016, China 2 State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou 730050, China
20% nano ZrO2 (3Y) powders were added to high purity submicron Al2O3 powders,then composite ceramics were prepared by high-pressure dry pressing and constant heating, multi-stage, short insulation sintering method at different temperatures. The effect of sintering temperature on mechanical properties of composite ceramics was investigated, the phase composition and microstructure of composite ceramics were analyzed by XRD, EDS and SEM. The results show that the sintering temperature affects the mechanical properties and microstructure of composite ceramics greatly. The relative density, vickers hardness and fracture toughness reach the maximum value, respectively 98.6%, 18.54GPa and 9.3MPa·m1/2 under atmospheric sintering at 1600℃ and insulation 8h. While the grain size of the matrix is about 1.4-8.1μm and ZrO2 phase transition is 34.6%. Composite ceramics have excellent microstructure sintered at 1600℃. The fracture mode of the composite ceramics is intergranular-transgranular mixed fracture mode. The fracture toughness of the composite ceramics is improved by phase transition toughening, intragranular particles toughening, crack deflection and other aspects when adding nano-sized ZrO2 (3Y) powder.
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