振荡压力烧结法制备高致密度细晶粒氧化锆陶瓷

针对重大工程和关键技术对高强韧性、高可靠性陶瓷部件的迫切需求, 本研究提出了适用于高性能陶瓷制备的振荡压力烧结(Oscillatory Pressure Sintering, OPS)新方法, 并采用此种方法制备了高致密度、细晶粒、高强度和高可靠性的氧化锆陶瓷。作为对比, 在相同的温度条件下分别采用无压烧结(Pressureless Sintering, PS)和热压烧结(Hot Pressing, HP)制备了氧化锆陶瓷。SEM研究表明振荡压力抑制了高温下氧化锆晶粒的快速生长, 统计表明OPS氧化锆的平均晶粒尺寸为251 nm, 而PS氧化锆、HP氧化锆的平均晶粒尺寸分别为451 nm和298 nm。另外, 振荡压力引发的晶粒塑性形变和晶界滑移促进了晶界处闭气孔的排出, 使OPS氧化锆的体积密度提高到99.7%。氧化锆致密度的提高及晶粒细化使其断裂强度从1003 MPa提高到1572 MPa, Weibull模数从13提高到32。另外, 低温老化实验表明OPS氧化锆的抗老化性能也得到显著提高。

Preparation of Zirconia Ceramics with High Density and Fine Grains by Oscillatory Pressure Sintering

To fulfill the demands of ceramic components with high strength, high toughness and high reliability in key projects, a novel oscillatory pressure sintering (OPS) method was proposed in this study. With this new method, zirconia ceramics with high relative density, fine grains, high fracture strength, and excellent reliability, were prepared. As a comparison, zirconia ceramics were sintered by pressure-less sintering (PS) method and hot pressing (HP) method at same temperature. SEM analysis shows that the oscillatory pressure inhibits the rapid grain growth of zirconia at high temperature. Statistic results indicate that the OPS zirconia presents fine grain size at 251 nm, while the average sizes of PS and HP zirconia are 451 and 298 nm, respectively. In addition, the oscillatory pressure induces plastic deformation of grains and sliding of grain boundaries, facilitating elimination of closed pores at grain boundaries. As a result, the relative density of OPS zirconia reaches approximately 99.7%. Due to the refinement of grains and the increase in relative density, the OPS zirconia presents an increase from 1003 MPa to 1572 MPa in flexural strength, and an increase from 13 to 32 in Weibull modulus. Furthermore, its resistance to low temperature degradation is also improved because of the microstructure evolution.