纳米非晶Si2N2O粉末的SPS烧结及烧结体性能研究

SPS sintering of amorphous nano-sized Si_2N_2O powders and characterization of its sintered bulks

通过低温还原,以Si_2OCl_6为原料,以Na溶液为还原剂,在液氨溶液中成功合成了纳米非晶态Si_2N_2O粉末.在不加任何烧结助剂的条件下,通过放电等离子体烧结,得到了致密的陶瓷块体.制得的纳米非晶粉末颗粒尺寸约为20 nm,XRD结果显示样品在1 100℃开始晶化.进一步考察了不同烧结温度下陶瓷的抗氧化性和力学性能,致密块体在1 600℃下经过20 h氧化后,其增重仅有1.1%,烧结块体的力学性能随着烧结温度的增加而迅速增加,当烧结温度高于1 500℃时,继续增加烧结温度力学性能的增加趋势变得平缓.1 500℃烧结样品的维氏硬度、强度和断裂韧性分别达到了19.6 GPa,440 MPa和4.1 MPa·m1/2.

Through XRD analysis,the obtained amorphous nano-sized Si2N2O powders,with the size of about20nm,began to crystallize at1100℃.By further investigating the oxidation resistance and mechanical properties of the ceramics sintered at different temperatures,the study found that the weight gain of dense bulks was only1.1%after twenty-hour oxidation at1600℃.The mechanical properties of sintered bulks increased rapidly with the increase of sintering temperature.When the temperature was over1500℃,the increasing tendency of the mechanical properties became slowly with the rise of temperature.The Vickers hardness,flexural strength and fracture toughness of the sintered samples at1500℃ reached19.6GPa,440MPa and4.1MPa·m1/2respectively.When Si2OCl6was taken as raw materials and sodium solution as the reducing agent,amorphous nano-sized Si2N2O powders were successfully synthesized in liquid ammonia solution through low temperature reduction.Thus dense ceramic bulks were obtained via spark plasma sintering without any sintering additives.