NIE Guanglin 1, 2, 3, LIU Leiren 2, LIU Yijun 3, ZUO Fei 2, BAO Yiwang 4, RAO Pinggen 1, WU Shanghua 2
(1. School of Materials Science and Engineering, South China University of Technology, Guangzhou 510641, Guangdong, China; 2. School of Electromechanical Engineering, Guangdong University of Technology, Guangzhou 510006, Guangdong, China; 3. Postdoctoral Research Center, Monalisa Group Co., Ltd., Foshan 528211, Guangdong, China; 4. State Key Laboratory of Green Building Materials, China Building Materials Academy, Beijing 100024, China)
Abstract: Al2O3@t-ZrO2composite ceramic powders were prepared by using a non-aqueous precipitation coating process, with ZrOCl2·8H2O and Y(NO3)3·6H2O as the precursors of t-ZrO2, diethylamine (DEA) as the precipitant and Al2O3 powder as the main raw material. Based on the complexation reactions of DEA with Zr 4+ and Y3+ and the heterogeneous nucleation mechanism, the zirconium/yttrium-amine complex precipitate can be coated on the surface of Al2O3 powder, which was then completely transformed to t-ZrO2 after heat treatment at 1000 ℃, resulting in Al2O3@t-ZrO2composite powders. The coating layer was composed of a large number of nanoparticles with an average size of 22 nm. ZTA (4 vol.% ZrO2) 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 ZrO2 in the Al2O3 matrix was improved owing to the use of the CP process, leading to ZTA ceramics with enhanced bending strength and fracture toughness.
Key words: precipitation coating process; composite ceramic powder; ZTA ceramic; coating layer; microstructure