新型振荡压力烧结工艺对高性能氮化硼陶瓷微观结构和性能的影响

Effect of Oscillatory Pressure Sintering Process on Microstructure and Properties of Boron Nitride Ceramics with High Performance

采用新型振荡压力烧结工艺(OPS)制备了h-BN陶瓷,研究了振荡压力对h-BN陶瓷烧结致密化以及晶粒生长的影响,并结合致密度、微观结构及断裂可靠性等因素,对不同烧结工艺下的氮化硼陶瓷的晶粒定向程度以及力学和热学性能进行了探究。研究表明:与采用热压烧结工艺(HP)制备的氮化硼陶瓷相比,采用OPS工艺制备的陶瓷表面更为致密,断面的晶粒定向排列逐渐清晰,高比例平行排列的片状BN晶粒能有效提高BN陶瓷的致密化程度。OPS试样的硬度、断裂韧性以及抗弯强度最高分别达到了0.31 GPa、1.09 MPa·m^(1/2)和74.4 MPa,较相同烧结参数下的HP试样有了大幅提升。结合XRD谱计算出的晶粒定向排列数据可知,振荡压力的引入明显促进了氮化硼陶瓷的致密化烧结,断裂可靠性和热导率均获得了提高。

High h-BN ceramics were prepared by an oscillatory pressure sintering technique(OPS),and the effect of oscillatory pressure on the sintering densification and grain growth of h-BN ceramics was investigated.Boron nitride ceramics were also prepared by a hot pressing sintering process(HP).The density,microstructure,fracture reliability,degree of grain orientation,mechanical and thermal properties of boron nitride ceramics at different sintering processes were analyzed.The results show that the fracture surface of OPS specimens is denser,and the grain orientation becomes clear,compared with those of HP specimens.A high proportion of parallel-arranged BN grains can effectively improve the densification of BN ceramics.The maximum hardness,fracture toughness and flexural strength of OPS specimens are 0.31 GPa,1.09 MPa·m^(1/2) and 74.4 MPa,respectively,which are greatly improved,compared with HP specimens at the same sintering parameters.According to the data of grain orientation determined by X-ray diffraction patterns,the application of oscillatory pressure obviously promotes the densification and sintering of boron nitride ceramics,thus improving the fracture reliability and thermal conductivity.