Study on Toughening Mechanism of Nano-Composite Ceramics Prepared by Mixed Coagulative Method

摘要

In this work the toughening mechanism and the microstructure of SPS-sintered Al_2O_3-ZrO_2 nano-composite ceramics whose powder was prepared by mixed coagulative method, was studied. The study showed that the grain shape of Al_2O_3 was changed due to the additive ZrO_2 and its density was improved in the Al_2O_3- ZrO_2 ceramics. Meanwhile its grain was refined. The microstructure was the typical nano-composite ceramics mixed with intracrystalline and intercrystalline structure. The irregular aggregation of ZrO_2 mostly existed on the grain boundary, where many grains of Al_2O_3 intersected. Some thin and dispersal globular nano grains (70nm-200nm) of ZrO_2 were distributed in the Al_2O_3 crystal grains. That enhanced the mechanical performance of the matrix because of the refined grain and the intracrystalline nanometer structure. The study also showed that the changes of the mechanical performance of Al_2O_3-ZrO_2(n) ceramic resulted from toughening mechanism introduced by nanometer grains, toughening mechanism introduced by ZrO_2 phase transition and the intracrystalline structure.