纳米非晶Si2N2O粉末的SPS烧结及烧结体性能研究

通过低温还原，以Si₂OCl₆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Si₂N₂O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. 

SPS sintering of amorphous nano-sized Si2N2O powders and characterization of its sintered bulks

Through XRD analysis, the obtained amorphous nano-sized Si₂N₂O powders, with the size of about 20 nm, began to crystallize at 1 100 ℃. 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 only 1.1% after twenty-hour oxidation at 1 600 ℃. The mechanical properties of sintered bulks increased rapidly with the increase of sintering temperature. When the temperature was over 1 500 ℃, 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 at 1 500 ℃ reached 19.6 GPa, 440 MPa and 4.1 MPa·m1/2respectively. When Si₂OCl₆ was 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.