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在热力学分析的基础上,以铁尾矿和碳黑为原料,采用碳热还原氮化法合成了Si3N4粉。利用X射线衍射(XRD)、扫描电镜(SEM)等技术测定了产物的相组成和显微结构,研究了合成温度为1450℃,恒温时间8 h,N2流量600 mL/min条件下原料组成(配碳比(C和Si O2摩尔比))对合成过程的影响。结果表明,配碳比对合成过程的影响非常显著,在实验条件下配碳比为2最佳。当配碳比小于2时,随配碳比的增加,产物中Si3N4相迅速增加;当配碳比大于2时,随配碳比的增加,产物中Si3N4相开始减少,而SiC相逐渐增多。配碳比为2时,产物中Si3N4晶粒多为等轴柱状或短棒状β-Si3N4。
Based on the thermodynamic analysis, Si3N4 powder was synthesized by carbothermal reduction nitridation using iron tailings and carbon black as raw materials. The phase composition and microstructure of the product were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effects of reaction temperature, 1450 ℃, and constant temperature for 8 h on the composition of With carbon ratio (C and Si O2 molar ratio)) on the synthesis process. The results show that the effect of carbon ratio on the synthesis process is very significant. Under the experimental conditions, the carbon ratio is 2. When the ratio of carbon to carbon is less than 2, the Si3N4 phase increases rapidly with the increase of carbon ratio. When the ratio of carbon to carbon is larger than 2, the Si3N4 phase begins to decrease and the SiC phase increases gradually with the increase of carbon ratio. With the carbon ratio of 2, the product Si3N4 grains mostly equiaxed columnar or short rod-shaped β-Si3N4.