【作者】 龚伦伦；

【导师】 张和平；

【作者基本信息】 中国科学技术大学 ， 安全科学与工程， 2014， 博士

【摘要】 近年来由于缺乏相关消防安全法规,大量可燃的有机保温材料被用于建筑外墙,造成了火灾事故频发。现阶段我国建筑外墙保温技术最突出的问题就是节能和防火之间的矛盾,有机保温材料虽然隔热性能好、质轻和价格便宜,但是可燃烧,一旦被点燃会释放大量的热量、烟气和毒性气体,并且会在建筑外立面上迅速蔓延,造成严重的后果,而无机保温材料防火性能优异,但是导热系数较大,而且易吸水,节能效率不高。本文从先防火再节能方面考虑,提出研发一种低导热系数、低成本、憎水和环境友好的无机外墙保温材料。本文采用理论分析与实验制备相结合的方法,利用发泡和固化法制备出导热系数较低,强度合适且具有憎水性的硅酸盐无机多孔保温材料,完成的主要研究工作如下：首先,研究了多孔保温材料内部的传热机理,发展了新型有效介质理论来描述多孔保温材料的内部传热。利用传热分析推导出理论的数学表达式并且验证了该理论的有效性,而且根据理论模型提出高孔隙率(或低容重)、低导热系数固相骨架与合理的孔隙结构这三种途径可以使多孔材料具有低导热系数,为研发工作提供了理论依据。然后,以工业莫来石粉为骨料和玉米淀粉为胶凝材料利用发泡和淀粉固化的方法制备了高孔隙率的莫来石基多孔保温材料,孔隙率最高的样品导热系数可以达到0.1W/mK左右,为研发工作奠定了实验基础。接着,针对发泡和淀粉固化法的缺点,以工业莫来石粉为骨料,用更经济更环保的水泥代替淀粉作为胶凝材料,利用发泡和水泥固化法制备了莫来石基多孔保温材料,降低了成本和减少了排放,优化了制备方法。最后,选择成本更低和更轻质的工业废料粉煤灰作为骨料,利用发泡和水泥固化法制备粉煤灰基多孔保温材料,并且采用发泡液先独立发泡再与浆料混合的方法代替之前的浆料直接发泡,制备出导热系数更低的样品。此外本文还使用水溶性防水剂对样品进行渗透性防水处理,经过防水处理后样品具有憎水性。更多还原

【Abstract】 In recent years, due to a lack of corresponding fire prevention codes, a lot of combustible organic insulation materials are used in building exterior walls, resulting in frequent occurrence of fire accidents. Now in China, the most prominent problem in building exterior insulation technology is the contradiction between energy conservation and fire prevention. Although organic insulation materials have excellent insulation performance, light weight and cheap cost, they are flammable. Once ignited, organic insulation materials will release a lot of heat, smoke and toxic gases, and furthermore the flame will quickly spread on the building facade, resulting in serious consequences. Inorganic insulation materials have outstanding fire performance, but they have large thermal conductivity, high water absorption and low energy conservation efficiency. Considering fire prevention priority, this paper proposed preparing a low thermal conductivity, low cost, environmentally friendly and hydrophobic inorganic insulation materials for building exterior walls.In this paper, through combining theory and experiments, inorganic porous insulation materials with a low thermal conductivity, suitable strength, and hydrophobic were prepared using foaming and setting method. The main research work is as follows:First, the heat transfer mechanism in porous thermal insulation material was studied. A novel effective medium theory was developed to describe the internal heat transfer of porous thermal insulation material. The mathematical expression of the theory was deduced by heat transfer analysis and the validity of the theory was also verified. According to the model, the thermal conductivity of porous materials can be decreased through three approaches, increasing porosity (or decreasing bulk density), decreasing the thermal conductivity of solid skeleton and holding a reasonable pore structure. This work provided theory basis for the whole research work.Then, industrial mullite powder and corn starch are used as the aggregate and cementing materials respectively and highly porous mullite insulation materials were prepared by foaming and starch consolidation method. The thermal conductivity of highest porosity sample can reach0.1W/mK. This work provided experimental basis for further research work.Next, aiming at the shortcomings of foaming and starch consolidation method, more economic and environmentally friendly cementing material cement are used to substitute corn starch and porous mullite insulation materials were prepared by foaming and cement consolidation method. This method solved the problem of the cost and discharge of organic material, and optimized the preparation method.Finally, lower cost and lighter weight industrial waste fly ash and cement were used as the aggregate and cementing material respectively for preparing fly ash based porous insulation material. Moreover, lower thermal conductivity samples were prepared by using foaming agent foaming independently first and then mixing with slurry instead of direct foaming method. In addition, samples were treated by water proof agent, and after the treatment samples became hydrophobic.更多还原