【作者】 徐圣；

【导师】 王玺堂；

【作者基本信息】 武汉科技大学 ， 材料学， 2007， 硕士

【摘要】 本文对碳热还原法制备Al₂O₃-SiC复相陶瓷粉末反应过程中的各种影响因素进行了较系统的研究。首先,对不同原料和不同还原剂之间的反应情况进行了对比,进而探讨了各种工艺条件对该碳热还原反应的影响,这些工艺包括温度、保温时间、碳含量和粒度大小等,在此基础上,考察了催化剂种类及催化剂加入量对反应的影响。研究表明,以粘土、废粘土砖粉和累托石为原料,以无烟煤或碳黑为还原剂,在适当的碳和氧化硅摩尔比且不低于1600℃的条件下,进行碳热还原反应,可以合成Al₂O₃-SiC复相陶瓷粉体,随着反应温度的升高,SiC峰强度增大;在原料和其他条件相同的情况下,碳黑的还原效果比无烟煤好。随着C/SiO₂的增加,SiC相的峰不断增强,当C/SiO₂为3～4时SiC的含量相对较多,由此可见,适当增加碳含量可以有效地促进反应的进行。在C/SiO₂不变的情况下,随着保温时间的延长,SiC和刚玉相的峰值都有增强的趋势;随着共磨时间的延长,也就是粒度越细,产物中的SiC峰有增强的趋势,说明延长保温时间和减小反应物的粒度都可以促进反应的进行。以氧化铁,氯化铁,硝酸铁,硝酸钴,硝酸镍等为催化剂,与不加催化剂的试样比较,结果表明这些催化剂都有助于碳热还原反应的进行。而且,适当增加催化剂的加入量,对反应的发生有进一步的促进作用。SEM观察发现Al₂O₃-SiC复相陶瓷中,SiC交错分布在刚玉之间,催化剂的加入有利于碳化硅和刚玉的发育生长。更多还原

【Abstract】 The influencing factors on preparing Al₂O₃-SiC composite ceramic powders by carbon thermal reduction method were studied systematically. Firstly, the effect of variety of raw materials on reaction was compared. Then the effects of technological conditions on the reaction were investigated, including temperature, soaking time, carbon content and particle size of raw materials, etc. Finally, the effect of catalysts and the addition of catalysts on the reactions were explored.The results show that Al₂O₃-SiC composite ceramics powders can be synthesized under the condition of proper C/SiO₂ mole ratio and over 1600℃, with clay, waste clay brick powder or rectorite as raw materials and anthracite coal or carbon black as reducers. XRD peak of SiC phase intensified with higher temperature. The reduction effect of carbon black is better than anthracite coal.XRD peak of SiC phase increased with the higher C/SiO₂ mole ratio and the most amount of content of SiC can be obtaind when the C/SiO₂ mole ratio is 3～4. It is obvious that increasing carbon content properly will promote the reaction.The content of SiC and corundum phases also increased with more soaking time and more grinding time, which means smaller grain size of raw materials. Apparently more soaking time and more grinding time will be beneficial to the reaction process.Compared with the reactions without catalyst, using Fe₂O₃, FeCl₃, Fe（NO₃）₃, Co（NO₃）₃ or Ni（NO₃）₃ as catalysts could accelerated the carbon thermal reduction reactions. Moreover, the reactions will be further promoted when increase the amount of catalyst properly.SEM results demonstrated that SiC phase interleave distributing in the corundum phase in the Al₂O₃-SiC composite materials. Catalysts are impetus to the growth of SiC and corundum.更多还原