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以铁合金行业的副产物-硅微粉(SiO2≥90%,质量分数)和闪速燃烧合成的β-Si3N4(β-Si3N4≥95%,质量分数)为原料,按质量分数β-Si3N4:SiO2=2:1的比例,分别将比表面积为1.19,1.67,2.48m2/g的β-Si3N4与SiO2均匀混合、成型,分别经1300、1400、1500、1600℃,3h埋碳(不接触碳)热处理,并对自然冷却后试样进行XRD、SEM分析。结果表明,β-Si3N4与SiO2从1300℃开始缓慢反应生成Si2N2O,随温度升高到1500℃以上时Si2N2O反应速度明显加快;在1300、1400℃,反应以固-固反应为主,β-Si3N4的比表面积对Si2N2O生成量的影响越大,比表面积大则Si2N2O生成量较高;在1500℃以上时,随着硅微粉收缩、液化,将β-Si3N4包裹、胶结到一起,反应方式以固-液反应为主,反应速度明显加快,加速了Si2N2O的形成,β-Si3N4的比表面积对Si2N2O生成量的影响不明显。
Based on the mass fraction of β-Si3N4: SiO2 = β-Si3N4 (β-Si3N4≥95%, mass fraction), which is the by-product of ferroalloy industry, 2: 1 ratio, respectively, the specific surface area of 1.19,1.67,2.48m2 / g of β-Si3N4 and SiO2 were uniformly mixed and shaped, respectively, by 1300,1400,1500,1600 ℃, 3h buried carbon (non-contact carbon) heat treatment , And the natural cooling of the sample after XRD, SEM analysis. The results show that Si2N2O slowly reacts with β-Si3N4 and SiO2 starting from 1300 ℃. The reaction rate of Si2N2O increases with increasing temperature above 1500 ℃. At 1300 and 1400 ℃, the reaction is mainly solid-solid reaction and β-Si3N4 Of the specific surface area of Si2N2O, the larger the specific surface area, the higher the amount of Si2N2O. Above 1500 ℃, as the silica powder shrinks and liquefies, β-Si3N4 is encapsulated and cemented together, and the reaction mode is solidified - liquid reaction, the reaction speed was significantly accelerated, accelerating the formation of Si2N2O, β-Si3N4 specific surface area of Si2N2O formation was not obvious.