基于非水基沉淀覆膜技术制备Al_(2)O_(3)@t-ZrO_(2)复合粉体

Preparation of Al_()2O_(3)@t-ZrO_(2) Composite Ceramic Powders via a Non-aqueous Precipitation Coating Process

以ZrOCl2·8H_(2)O和Y(NO_(3))_(3)·6H_(2)O为t-ZrO_(2)的前驱体、二乙胺为沉淀剂、Al_(2)O_(3)粉体为原料,采用非水基沉淀覆膜(CP)技术制备了Al_(2)O_(3)@t-ZrO_(2)复合陶瓷粉体。t-ZrO_(2)前驱体的沉淀覆膜行为的研究结果表明,利用Zr4+、Y3+与乙二胺的络合反应,通过异质形核机制,可在非水基环境下于Al_(2)O_(3)陶瓷粉体表面引入Zr/Y-胺络合物沉淀;且经1000℃热处理,Zr/Y-胺络合物沉淀可转变为t-ZrO_(2),继而制得Al_(2)O_(3)@t-ZrO_(2)复合粉体。TEM和XPS测试结果证明,CP技术可实现t-ZrO_(2)在Al_(2)O_(3)粉体表面的成功包覆,且包覆层由大量的t-ZrO_(2)纳米粒子(平均粒径≈22nm)所组成。分别利用传统球磨(BM)技术与CP工艺,经干压成型、无压烧结制得ZTA(4 vol.%ZrO_(2))陶瓷;ZTA陶瓷的微观结构与力学性能测试结果表明,CP可优化t-ZrO_(2)在Al_(2)O_(3)基体中的分散均匀性,继而可提升ZTA陶瓷的弯曲强度与断裂韧性。

Al_(2)O_(3)@t-ZrO_(2) composite ceramic powders were prepared by using a non-aqueous precipitation coating process,with ZrOCl2·8H_(2)O and Y(NO_(3))_(3)·6H_(2)O as the precursors of t-ZrO_(2),diethylamine(DEA)as the precipitant and Al_(2)O_(3) powder as the main raw material.Based on the complexation reactions of DEA with Zr~(4+)and Y~(3+)and the heterogeneous nucleation mechanism,the zirconium/yttrium-amine complex precipitate can be coated on the surface of Al_(2)O_(3) powder,which was then completely transformed to t-ZrO_(2) after heat treatment at 1000℃,resulting in Al_(2)O_(3)@t-ZrO_(2) composite powders.The coating layer was composed of a large number of nanoparticles with an average size of 22 nm.ZTA(4 vol.%ZrO_(2))ceramics were fabricated by using the traditional ball-milling(BM)method and CP process,respectively,combined with dry pressing and pressure-less sintering.It is found that the dispersion uniformity of ZrO_(2) in the Al_(2)O_(3) matrix was improved owing to the use of the CP process,leading to ZTA ceramics with enhanced bending strength and fracture toughness.