ZrO_2增韧Al_2O_3陶瓷的力学性能和增韧机制

Mechanical properties and toughening mechanisms of ZrO_2 toughened Al_2O_3 ceramics

对通过热压烧结法制备的3种陶瓷99.5vol%Al2O3(AD995)、ZrO2(15vol%)/Al2O3和ZrO2(25vol%)/Al2O3的力学性能和增韧机制进行了实验和理论研究。基于复合材料细观力学理论并考虑ZrO2的相变特性,建立了描述ZrO2/Al2O3陶瓷力学性能的本构模型。结果表明:ZrO2的加入细化了基体Al2O3晶粒,ZrO2/Al2O3陶瓷的致密性得到提高;3种陶瓷试件的破坏呈现小变形到脆性破坏的特点,压缩加载下试件应力-应变曲线近似为线性关系;AD995陶瓷的断裂韧性为5.65 MPa·m1/2,ZrO2(25vol%)/Al2O3陶瓷的断裂韧性为8.42 MPa·m1/2,提高了近50%;随ZrO2增韧相含量的增加,ZrO2/Al2O3陶瓷的弹性模量降低而断裂韧性增加,这一变化趋势与实验结果有良好的一致性。

Mechanical properties and toughening mechanisms of three ceramics,99.5vol% Al2O3(AD995)ceramic,ZrO2(15vol%)/Al2O3 ceramic and ZrO2(25vol%)/Al2O3 ceramic prepared by hot pressing sintering were investigated by experimental and theoretical research.Based on the micro-mechanics theory of composites,a micromechanical constitution model was developed to describe mechanical properties of ZrO2/Al2O3 considering phase transformation of ZrO2.The results show that the grain size of Al2O3 matrix decreases and densification is improved with addition of ZrO2.The failure of three ceramic specimens show characteristic of small deformation to brittle failure.The compression stress-strain curves show an approximately linear relationship.The fracture toughness of AD995 ceramic is 5.65 MPa·m1/2,while ZrO2(25vol%)/Al2O3 is 8.42 MPa·m1/2,approximately 50% improvement.With toughening phase ZrO2 content increasing,elastic modulus of ZrO2/Al2O3 decreases and fracture toughness increases,which are consistent with experimental results.