【作者】 周军；

【导师】 孙清池； 王刚；

【作者基本信息】 天津大学 ， 材料工程， 2008， 硕士

【摘要】 Al₄SiC₄材料由于其高熔点（约2037℃）、良好的导热性和抗高温熔体、熔渣的侵蚀性[1],在功能耐火材料方面有着良好的应用前景。将其作为添加剂添加到含碳材料中,来改善含碳材料性能日益引起人们的关注。本课题对高温自蔓延法制备Al₄SiC₄粉体进行了较为系统的研究,并通过采用自制的Al₄SiC₄粉体作为添加剂添加到铝碳质材料中,研究其对材料性能的影响。结果表明:1、粉体制备方面:（1）采用点燃的C和Ti粉混合物为化学炉,可以通过高温自蔓延反应制备Al₄SiC₄粉体,而在常规自蔓延合成条件下反应不能进行。（2）Al₄SiC₄的合成反应分两步进行:首先由单质Al、Si和C反应生成SiC和Al₄C₃,然后再由SiC和Al₄C₃反应合成Al₄SiC₄。（3）C含量过量30%的配比能够制备出不含Al₄C₃相、Al₄SiC₄含量可达80%的粉体。（4）金属Al粉粒度的减小有利于Al₄SiC₄相的发育。2、性能研究方面:（1）Al₄SiC₄的添加可降低含碳材料的显气孔率,提高结构致密度,一定程度改善材料的常温性能,显著提高试样的高温抗折强度。（2）Al₄SiC₄先于C发生氧化反应,生成固态物质沉积在气孔内或固体表面,形成莫来石致密保护层,抑制氧化性气体的扩散,同时还原出C,对含碳材料具有自修复作用,对提高含碳材料抗氧化性具有显著效果。（3）Al₄SiC₄具有优良的抗水化性,可改善金属Al对含碳材料带来的不利影响,替代含金属Al的添加剂具有较好的应用前景。（4）在熔钢接触面处,Al₄SiC₄氧化形成莫来石致密层,可以减缓石墨的氧化溶解及熔钢的渗透,可显著提高材料的抗熔钢侵蚀性和冲刷性。由以上结果综合考虑得出,高温自蔓延法是制备Al₄SiC₄粉体的一种有效途径,该方法简便快捷,能耗低。利用这种方法制备的Al₄SiC₄粉体作为添加剂加入到铝碳材料中可有效改善材料的高温性能,尤其在抗氧化性、抗水化性和抗钢水冲刷性方面表现优异,弥补目前较普遍使用的含铝添加剂存在的缺陷,是一种理想的含碳材料添加剂。更多还原

【Abstract】 Al₄SiC₄ has well application prospect in functional refractory materials due to its high melting-point （about 2037℃）、high thermal conductivity and higher corrosion resistance to high-temperature melt and slag. It has been of great interesting to add Al₄SiC₄ into carbon containing refractory as an additive to improve the properties of the materials.This experiment systematically studies the preparation of self-propagating high temperature synthesis of Al₄SiC₄ powders, and the influence on the properties of alumina-graphite material added to Al₄SiC₄ powders as an additive. Conclusions are drawn as following:1. Preparation（1） Al₄SiC₄ powders can be obtained by C.O.SHS（chemical oven SHS） with C and Ti mixture powders ,but it can’t be synthesized by common SHS.（2） The synthesis of Al₄SiC₄ powders includes two steps: first of all, SiC and Al₄C₃ are reacted from simple substance of Al、Si and C, then Al₄SiC₄ is synthesized by SiC and Al₄C₃.（3） Powders with 80wt% of Al₄SiC₄ powders but without Al₄C₃ phrase are obtained from the composition with 30% of carbon.（4） To minish the crystal gravesize of metal Al powders is in favor of the growth of Al₄SiC₄.2. The effect on properties（1） The addition of composition Al₄SiC₄. can decrease the apparent porosity, increase the density of structure, improve the cold modulus of rupture （CMOR） of the alumina-graphite materials to a certain extent and markedly increase the hot modulus of rupture （HMOR）.（2） Because Al₄SiC₄ is oxidized before the graphite, the created solid matter deposits into the pore or at the surface of solid and then forms a dense protective layer of mullite, and C can serves as a barriev for the diffusion of oxygen from the exterior into the interior, which provides the self-repair and remarkable effect on the oxidation resistance of the carbon containing refractory with Al₄SiC₄.（3） Al₄SiC₄ has excellent hydration resistance, and is helpful to advided the bad effect of the metal Al on the carbon containing refractory, and can replace the additives metal Al, therefore, it has a better application prospect. 4)At the contact face of melt steel, Al₄SiC₄ forms a dense layer of mullite by oxidation, which makes the oxidizing dissolving of graphite and the penetration of the melt steel to slower, so as to markedly improve the corrosion resistance to the melt steel of the materials.In conclusion, Self-propagating high temperature synthesis is an effective preparation way of Al₄SiC₄ powders, which is quick and simple, with lower energy consumption. The obtained powder has excellent properties which meet the demands of the additive of carbon containing refractory, is remarkably improve the properties in room and high temperature of the alumina-graphite materials, especially, in resistance to oxidation, hydration and erosion of melt steel. Therefore, it may remedy the defect of the common Al containing additive, and can be used better than additive to carbon containing refractory.更多还原