闪烧致密Al_(2)O_(3)-ZrO_(2)复相陶瓷的微观结构及力学性能

Microstructure and mechanical properties of dense Al_(2)O_(3)-ZrO_(2)composite ceramic via flash sintering treatment

以α-Al_(2)O_(3)和氧化钇稳定氧化锆粉体为原料,无压烧结制备致密Al_(2)O_(3)-ZrO_(2)复相陶瓷,在临界电场下进行热处理后,对Al_(2)O_(3)-ZrO_(2)复相陶瓷的微观结构和力学性能进行研究。结果表明:在900 V/cm的电场下,烧结致密Al_(2)O_(3)-ZrO_(2)复相陶瓷的闪烧起始炉温为308℃。在炉温为1200℃、电场为700 V/cm的条件下,闪烧致密Al_(2)O_(3)-ZrO_(2)复相陶瓷原位合成Al_(2)O_(3)-ZrO_(2)共晶结构。闪烧陶瓷主要分为复相区、过渡区和共晶区3个区域。复相区的微观结构与烧结陶瓷相似,形状不规则的Al_(2)O_(3)和ZrO_(2)相均匀分布;过渡区晶粒异常长大,粗大的Al_(2)O_(3)和ZrO_(2)相均匀分布;共晶区则呈现典型的Al_(2)O_(3)-ZrO_(2)共晶结构。共晶区的维氏硬度和韧性分别为17.94 GPa和3.51 MPa·m^(1/2),与采用定向凝固技术制备的Al_(2)O_(3)-ZrO_(2)共晶陶瓷的力学性能相当。

Dense Al_(2)O_(3)-ZrO_(2)composite ceramics were prepared by pressureless sintering usingα-Al_(2)O_(3)and yttria stabilized zirconia powders as raw materials,conducting heat treatment under critical electric field,and the microstructure and mechanical properties of the composite ceramics were investigated.Results indicate that the onset temperature of flash sintering for sintered dense Al_(2)O_(3)-ZrO_(2)composite ceramic is 308℃under an electric field of 900 V/cm.Al_(2)O_(3)-ZrO_(2)eutectic zone is in-situ synthesized in the dense Al_(2)O_(3)-ZrO_(2)composite ceramic using flash sintering at 1200℃and 700 V/cm.The flash sintered ceramic is divided into three zones:composite zone,transition zone,and eutectic zone.In the composite zone,the Al_(2)O_(3)and ZrO_(2)phases are irregular shapes and uniformly distributed,where there is similar microstructure to the sintered ceramic.In the transition zone,the abnormal grain growth is observed,and the coarse Al_(2)O_(3)and ZrO_(2)phases are evenly distributed.In the eutectic zone,it possesses the typical microstructure of Al_(2)O_(3)-ZrO_(2)eutectic ceramic.The Vickers hardness and toughness of eutectic zone are 17.94 GPa and 3.51 MPa·m^(1/2),respectively,which are comparable to those of Al_(2)O_(3)-ZrO_(2)eutectic ceramic fabricated by directional solidification technique.