【作者】 付英；

【导师】 曾令可；

【作者基本信息】 华南理工大学 ， 材料学， 2010， 硕士

【摘要】 将相变材料同耐腐蚀性好的常规材料复合是高温相变材料的研究方向之一,目前对于高温蓄热材料(>600℃)的研究主要集中在采用无机盐和陶瓷基制备复合制备相变蓄热材料,但都普遍存在着复合材料中相变盐含量过低的缺点。本文创新性地以工业废渣电石渣和硅灰为原料,采用动态水热法制备了超轻硬硅钙石型硅酸钙,并对合成产物的微观结构和形貌、孔结构参数进行了考察,并探讨了其作为复合相变储能材料基体的可能性和优势。结果表明:含有微量杂质的工业废渣原料对合成的硬硅钙石晶体及微观形貌基本上没有影响,不必因杂质的存在而对水热合成工艺参数做特殊调整,且采用抽滤法制备的硬硅钙石基体的成型方法简单、基体形状可调,实验中制备出圆柱状、球状的基体材料。以无水硫酸钠、氯化钾、氯化钠作为相变材料,硬硅钙石作为基体材料,通过熔融浸渗法制备了浸渗率达到90%的三种复合储能材料。分析讨论了熔融浸渗法的制备机理,考察了浸渗温度、浸渗时间等影响因素对制备过程的影响,从而最终确定了最优制备条件。利用XRD、SEM等手段分析了相变材料和基体材料的结合情况,结果表明:两相结合紧密,并具有良好的高温化学稳定性,两相仅仅是因浸润结合而形成的机械嵌合作用。利用DSC、热膨胀仪、激光导热仪等手段综合考察了所制备的复合材料的储能性能、导热系数、热膨胀特性以及热循环稳定性等,结果表明:复合储能材料的热物理特性主要是由无机盐的含量和自身的特性决定的,相变潜热和储热密度(ΔT=100℃)、热膨胀系数与相变材料的质量百分含量(即浸渗率)成正比;三种复合储能材料的最大平均热膨胀系数高于一般陶瓷氧化物的热膨胀系数。复合相变储能材料的导热系数、比热容以及热扩散率并没有受到基体材料具有绝热特性的限制,其值均高于一般的显热陶瓷材料的热学性能指标。本研究成功制备出具有高浸渗率,较高使用温度范围的无机盐/硬硅钙石基复合储能材料,制备方法简单、操作容易;同时采用工业废渣作为原料制备了具有良好的环境友好性的超轻硬硅钙石材料,达到了废物利用和环保的目的,也使超轻质硅酸钙材料得到多用途的推广应用;该研究拓展了新型相变储能复合材料制备研究的领域,同时也为推进其更广泛的研发应用奠定了基础。更多还原

【Abstract】 One of the main directions of preparing a high temperature phase change material is to make PCM complex in a common matrix with the feature of good corrosion resistance. Many studies present that inorganic salt/ceramic phase change materials will be a hopeful way to prepare a energy material for high temperature workplace(>600℃),but at present the main results show that the disadvantage is the low content of salt in composite phase change materials.Ultra-light xonotlite-calcium silicate was synthesized via hydrothermal processing, by novelly using carbide slag and silica fume as the raw materials, and the microstructure, parameters of pore structure of synthesized xonotlite were studied in this thesis, the possibility and superiority of xonotlite being used as the basic body of composited phase change energy storage materials were also discussed at the same time. The results indicated that the process parameters of hydrothermal synthesis did not need to adjust even though carbide slag and silica fume containing a small amount of impurities. The shape-stabilize xonotlite body was produced by vacuum forming technology, which has advantages of simple equipment and easy shape controls, and cylindrical xonotlite body and globular xonotlite body were produced in this thesis.Through infiltrating experiment, Na2SO4/Xonotlite composite phase change energy storage material, NaCl/Xonotlite composite phase change energy storage material, KCl/Xonotlite composite phase change energy storage material were fabricated successfully, and the infiltration percentage is 90%. The mechanism and influence factors of infiltrating process are studied in this thesis, the infiltration technology was ascertained after discussing the correlation of infiltration temperature, infiltration percentage. The practical combination of phase change material with xonotlite body was studied using XRD and SEM measurements, and the results showed that high temperature chemical compatibility and wetting between molten salt and xonotlite body, no new substance appeared, xonotlite body and molten salt were combined very well with wetting and mechanical inserting.The thermo-physical properties including latent heat, heat storage density, conductivity, specific heat, thermal diffusivity, thermal expansion coefficient and thermal cycle were studied by using Differential Scanning Calorimetry (DSC), laser thermal constant instrument and dilatometer. The results showed that the contents and the properties of PCM were major determinants of the thermodynamic properties of composite phase change energy storage materials, the latent heat, heat storage density and thermal expansion coefficient were proportional to PCM contents. The values of thermal expansion coefficient that all three prepared composite phase change energy storage materials showed were higher than common ceramics, and the thermal conductivities of composite materials were all higher than the value of common ceramics.Three new composite phase change energy storage materials with the advantage of high infiltration percentage and high temperature recycle scope were prepared successfully, it is also a good method to prevent pollution and make use of waste by synthesizing environmental friendliness xonotlite-calcium silicate via hydrothermal processing, by novelly using carbide slag and silica fume as the raw materials, and provided a new application for xonotlite at the same time. This work set a new direction for preparation of composite phase change energy storage materials,and laid the groundwork for practical applications in the future.更多还原