热压法制备碳纳米管增强3Y-ZrO_2陶瓷的工艺与性能

Technologies and properties investigations of CNTs reinforced 3Y-ZrO_2 ceramics with hot-pressing sintering

采用杂凝聚的方式制备CNTs(CNTs为碳纳米管Carbon nanotubes)分散均匀的3Y-ZrO2/CNTs混合粉体,热压后得到3Y-ZrO2/CNTs复合陶瓷块体材料。与普通球磨混料法制备的陶瓷样品进行对比,研究CNTs含量以及CNTs的分散性对3Y-ZrO2/CNTs复合陶瓷的组织、密度、断裂韧性以及电学性能的影响,并分析CNTs对陶瓷的增韧机理。结果表明,采用杂凝聚处理有助于CNTs在3Y-ZrO2/CNTs复合陶瓷中的均匀分散,CNTs含量(质量分数,下同)为1.00%的3Y-ZrO2/CNTs复合陶瓷的断裂韧性达到(18.13±0.50)MPa·m1/2,较球磨混料法制备的样品提高35.10%。陶瓷基体中均匀分散的CNTs不仅通过促进马氏体相变起到增韧作用,而且CNTs的桥联和拔出机制也直接起到增韧的作用。CNTs在陶瓷基体中均匀分散能大幅降低复合陶瓷的导通阈值。经杂凝聚预处理的CNTs含量为4.00%时,3Y-ZrO2/CNTs复合陶瓷的电导率达到4.467 S/m,比不含CNTs的3Y-ZrO2陶瓷高13个数量级;当CNTs含量为1.00%时,复合材料的相对介电常数达到6 340,比未经杂凝处理的样品高2个数量级。

The key to toughen 3Y-ZrO2 ceramics with CNTs lies in its dispersion condition in the matrix. In the present article, the heterocoagulation method aided by the ultrasonic dispersing and spray drying techniques were used to pretreat the mixture of CNTs and ZrO2 powder, and hot-pressing was employed subsequently to fabricate the solid composite ceramics. The experiment results indicate that the heterocoagulation method is much helpful to the uniform dispersion of CNTs in the ZrO2 matrix. The composite with content of 1.00wt% CNTs can be toughened as high as （18.13＆#177;0.50） MPa＆#183;M1/2 after hot-pressing （1 400℃/2 h/50 MPa）, or 35.10%increase in relative value compared with that of the blank one. The uniformly dispersed CNTs can be toughened not only by promoting the martensitic transformation, but also by the bridge and pull-out effects as well. The electric properties results also show that good dispersion of CNTs in matrix can greatly reduce the turn-on threshold. As CNTs have been heterocoagulated, the electrical conductivity of 3Y-ZrO2/CNTs composite ceramics with 4.00wt% CNTs can be as high as 4.467 S/m, which is 13 order of magnitude higher than that of the blank one;and the relative dielectric constant with 1.00wt%CNTs can be as high as 6 340, which is 2 order of magnitude higher than that of the composite in which CNTs is not heterocoagulaed.