中文摘要：

以亚微米级氮化硅为原料、Al2O3–Y2O3为烧结助剂,利用放电等离子烧结（spark plasma sintering,SPS）烧结技术制备氮化硅陶瓷。用X射线衍射和扫描电子显微镜对试样的物相组成和显微结构进行分析,研究了烧结温度对氮化硅陶瓷力学性能和显微结构的影响。结果表明,采用SPS烧结技术可在较低温度下获得致密度较高、综合力学性能较好的β相氮化硅陶瓷。随着烧结温度的提高,样品致密度、抗弯强度、断裂韧性均不断增大,在1 550℃时,其抗弯强度和断裂韧性分别达到973.74 MPa和8.23 MPa？m1/2。在1 550℃以下,陶瓷样品中β相氮化硅含量可达到98%,显微结构均匀,晶粒发育良好、呈长柱状,晶间紧密连接,晶间气孔较少。继续升高温度,部分晶粒发生异常长大,产生了更多的显微孔洞,抗弯强度急剧下降。

英文摘要：

The high-performance silicon nitride ceramics were prepared via spark plasma sintering （SPS） with submicron-sized powder of silicon nitride as a raw material and A12O3-Y2O3 as a sintering aid. The phase constitution and microstructure of specimens were analyzed by X-ray diffraction and scanning electronic microscopy. The effect of sintering temperature on the microstructure and mechanical properties of silicon nitride ceramics were investigated. The results show that β-phase silicon nitride ceramic with a high density and good mechanical properties can be obtained at a lower sintering temperature by SPS. The density, flexural strength and fracture toughness of the samples improve with the increase of the sintering temperature. The flexural strength and fracture toughness of the samples sintered at 1 500 ℃ are 973.74 MPa and 8.23 MPa＇m1/2, respectively. According to the phase composition and microstrueture analysis, the β-phase content of silicon nitride ceramics is 98%. The elongated columnar silicon nitride grains are uniform and well-developed. The compact connection between the grains results in the less pores of grain boundaries. The abnormal growth of some grains produces the more microscopic pores, leading to that the flexural strength decreases as sintering temperature further incerases.