“塑性”CePO_4陶瓷的微观结构与性能

MICROSTRUCTURE AND PROPERTIES OF "DUCTILE" CePO_(4) CERAMIC

针对应力应变曲线呈现明显非线形的"塑性"CePO4陶瓷,对其微观结构和性能进行了研究。化学法制备的CePO4颗粒随煅烧温度的升高逐渐长大。坯体在1500℃,2h烧结后的弯曲强度和断裂韧性分别为184MPa和4.8MPa·m1/2。实验发现:CePO4晶粒呈阶梯或层片状断裂形式,烧结体可用传统金属加工刀具方便地进行切削、车削和钻孔,并在车削表面发现连续的微观加工碎屑。材料的应力应变曲线呈现明显的非线性。同时,微观结构显示:受挤压表面沿挤压方向破坏前产生大量垂直于应力方向开裂的微裂纹。结果表明:CePO4陶瓷具有"塑性"或"延性"特征。基于挤压开裂的断口分析,初步认为CePO4陶瓷的"塑性"源于外力作用下自身层片结构的解理开裂、蔓延,并为适应外力进行的晶粒重排与调整。

The microstructure and properties of ductile CePO4 ceramic were investigated. The results show that the average grain size of CePO4 powder synthesized by chemical method increases with the increasing of calcining temperature. The bending strength of 184 MPa and the fracture toughness of 4.8 Mpa&middotm1/2 were achieved when the green compacts were sintered at 1500°C for 2 h in air. It is shown that stepped or multilayered fractures occur in CePO4 granules. CePO4 ceramic can be cut, drilled or turned easily using conventional metal-machining tools. Continuous machining debrises were observed on the turned surface. Indentation pressure stress-strain curves show the extensive nonlinear behavior and a series of microcracks on the extruded surface which are cross and occur along the extrusion stress direction. It is indicated that the single-phase CePO4 ceramic is ductile. Based on the fracture analysis of cross-section surface, the ductility of CePO4 ceramic is associated with the cleavage of multilayer CePO4 grains and the fragment resetting for the adaptation to stresses.