【作者】 满亚辉；

【导师】 吴文健；

【作者基本信息】 国防科学技术大学 ， 材料科学与工程， 2010， 博士

【摘要】 针对相变材料在热红外假目标伪装领域的应用需求,以相变材料结构和相变机理研究为基础,进行了相变潜热影响机制和微观本质的探讨,建立了示假性能的多因素综合影响的数学模型,解决了相变材料在热红外示假领域应用的关键技术难题。首先,通过氧化反应、接枝共聚反应研究有机相变材料的分子间作用力与相变潜热的关系。动态分析了脂肪烃类、脂肪醇类及脂肪酸类相变材料的分子量、分子极性和分子结构对相变潜热影响的本质因素,建立了相变潜热与影响因素间的定量关系,发现了有机材料相变潜热存在最高限值。然后,合理设计实验和测试方案,将无机水合盐复杂的相变过程拆分细化,发现一个新的现象:水合盐的相变形式除了结晶水的脱除和结晶外,还存在另外一种形式,即水合盐在相变点直接熔化形成熔体而发生固-液相变;通过热力学计算分析还发现,脱结晶水发生相变的水合盐,其相变潜热除传统观点认为的脱结晶水吸热外,还包括后续两个连续过程的热效应:脱水后无机盐溶解于结晶水中的溶解热、溶解过程中产生的浓差热效应。以上两种相变形式的结晶水平均相变潜热分别为12kJ·mol^-1和7kJ·mol^-1。其次,采用遗传程序设计、ANSYS软件模拟分析和实测数据,定量分析了相变潜热、热导率、环境温度、风速、材料厚度和形状等各因素对假目标示假效能的影响,并建立了多因素综合影响的数学模型,发现了一些重要的客观规律,如示假效能与表面积无关,与热导率有较大关联。这些结论对后续相变材料热红外假目标的设计起到了很好的指导作用。最后,对相变材料热红外假目标技术实际应用的关键难题进行了研究。分析得出典型目标特征部位及其红外暴露征候,为热红外假目标的热区设计和相变材料选择提供了依据;提出了野外自加热的供能技术及三层复合结构,并对高、低温自加热体系进行了改性,高温自热体系有效作用时间提高了4倍,低温自热体系热启动时间由2h缩短至5min,成功地解决了示假前相变材料的熔化、示假后相变材料保温的兼容性难题。更多还原

【Abstract】 Based on the research of the structure of phase change material and the mechanism（s） of phase transition, the effects and the microscopic nature of latent heat were studied to meet the application demands of phase change materials in the thermal infrared decoy camouflage field. Further experiments were carried out to study the factors that determine the decoy capabilities of the phase change materials, the research results provided practical protocols for the application of phase change materials in the thermal infrared decoy camouflage.The relationship between inter-molecular interaction and latent heat was studied by oxidation and the graft copolymerization reaction. How the molecular weight, polar group, and molecular structure affect the latent heat of the organic materials were studied in detail by danamic analyze. The quantitative relationships between latent heat and variable were established. The novel result was found: The latent heat was not always increased when inter-molecular interaction was increased, and it had the maximum.Experiments were designed to determine the composition of the phase change latent heat of inorganic salts. A novel solid-liquid phase change form was also observed when solid materials melt at the phase change temperature. The thermodynamics calculation of the obtained results demonstrated that the latent heat of inorganic salts consists of three parts, which are dehydration enthalpy, solution enthalpy, concentration enthalpy. A quantitative correlation between the number of crystal water and the molar latent heat of inorganic salt was established. The molar latent heat was determined to be 7 kJ·mol^-1 when phase change occurred after the crystal water was missed, while a 12 kJ·mol^-1latent heat was detected when inorganic material melted at the phase change temperature.The effects of different factors including phase change latent heat, thermal conductivity, environment temperature, wind velocity, material thickness, and shape on decoy camouflage were quantitatively analyzed using ANSYS programs and Genetic Programming Design for single-factor and multi-factor analysis, respectively. The predicted results were further confirmed by experiments. It was concluded that the decoy capabilities was dramatically affected by thermal conductivity whereas the shape demonstrated subtle effect on decoy capabilities. The emprical formula was successfully applied to the design of thermal infrared decoy.The infrared exposure profile of typical object was determined to provide critical information on the design of thermal infrared decoy and the selection of phase change materials. An improved self-heating material was developed based on the previously reported materials to meet the outdoor heating requirements. A three-layer material consisting of self-heating, temperature-keeping, and phase change materials was designed to solve the technical problems that prevent thermal infrared decoy from being practically applied.更多还原