Synthesis and characterization of AI_2O_3(matrix)-30ZrO_2 and AI_2O_3(matrix)- 30Y_(01)Zr_(0.9_0_2 nanocomposites

摘要

Tetragonal zirconia in alumina matrix is known as Zirconia Toughened Alumina (ZTA). ZTA ceramics are attractive materials due to the combination of both ZrO_2 (high strength and fracture toughness) and Al_2O_3 (high hardness and wear resistance) properties. This work reports the synthesis of ultra-fine Al_2O_3-ZrO_2 powders (20-200 nm) through the wet chemical route. Hundred percent tetragonal ZrC>2 can be found in the sintered body Al_2O_3(matrix)-30%Y_(0.1)Zr_(0.9)O_3 at 1600° C/2 h with 98% densification. The fine ZrO_2 (100-300 nm) has been homogeneously dispersed within the alumina matrix with a maximum grain size of 0.8 urn, which will increase the toughness of the alumina matrix. High fracture toughness of Al_2O_3-30%Y_(0.1)Zr_(0.9)O_2 is attributed to the presence of a coupled mechanism of stress-induced transformation toughening and transformation-induced microcrack toughening, and high flexural strength of the ceramics is a coupled result of small-size flaw and high fracture toughness. Because of no amorphous phases and grain boundaries but clean and stable phase interfaces in the ceramic composite, the Al_2O_3(matrix)-30%ZrO_2 and Al_2O_3(matrix)-30%Y_(0.1)Zr_(0.9)O_3 obtained in the experiment are promised to have excellent strength retention and high creep resistance at high temperature, compared to ones prepared by powder sintering method.