BaNb_2O_6/Al_2O_3复相陶瓷的制备及力学性能

Fabrication and Mechanical Property of BaNb_2O_6/Al_2O_3 Composite Ceramics

为研究功能材料对结构陶瓷微观结构和力学性能的影响,将铁电相BaNb2O6引入到Al2O3陶瓷中,分别采用无压和热压烧结技术于1350℃制备BaNb2O6/Al2O3复相陶瓷,对其物相组成、微观结构和力学性能进行了研究。结果表明:BaNb2O6与Al2O3经过高温烧结能够稳定共存,BaNb2O6的加入促进了Al2O3陶瓷的烧结。BaNb2O6加入量为10%(体积分数)时,1350℃无压烧结和热压烧结制备的BaNb2O6/Al2O3复相陶瓷的致密度、抗弯强度和断裂韧性分别为94.6%、214MPa、2.28 MPa m1/2和99.3%、332 MPa、3.55MPa m1/2。当裂纹扩展遇到BaNb2O6晶粒时发生穿晶断裂,但在晶粒内部出现裂纹偏转,说明铁电相BaNb2O6晶粒内部的微观结构有助于陶瓷的强韧化。

To investigate the impact of functional material on microstructure and mechanical properties of structural ceramics, a ferroelectric phase BaNb2O6 was incorporated in alumina ceramic. The BaNb2O6/Al2O3 composite ceramics were sintered at 1 350 ℃ by pressureless sintering and hot-press sintering, respectively. The phase composition, microstructure and mechanical properties of BaNb2O6/Al2O3 composite ceramics were investigated. The results show that BaNb2O6 is compatible with Al2O3 after high-temperature sintering. The addition of BaNb2O6 improved the sinterability of Al2O3 ceramics. The bulk density, flexural strength and fracture toughness of BaNb2O6/Al2O3 composite ceramics with BaNb2O6 of 10% （volume fraction）, which were fabricated by pressureless sintering and hot press at 1 350 ℃, were 94.6%, 214 MPa and 2.28 MPa.m^1/2 and 99.3%, 332 MPa and 3.55 MPa.m^1/2, respectively. Transgranular fracture occurred when the crack propagation encountered BaNb2O6 grains, but the crack deflection appeared inside BaNb2O6 grains. It was indicated that the internal microstructure of the ferroelectric phase BaNb2O6 grains could favor to improve the strength and toughness of the ceramics.