【作者】 王强；

【导师】 戴景民；

【作者基本信息】 哈尔滨工业大学 ， 仪器科学与技术， 2009， 博士

【摘要】 本课题来源于航天材料及工艺研究所“防隔热材料高温热物性测量技术”研究课题;目的是开发一种适合于防隔热材料的高温高精度热物性测量方法、研制并建立一套防隔热材料高温热物性测量装置、完善防隔热材料高温热物性测量标准以及建立我国第一个防隔热材料高温热物性数据库,从而达到服务我国防隔热材料研制、服务热防护系统设计以及服务国防及航天发展的目标。本论文紧密围绕国防及航空、航天领域对防隔热材料高温热物性数据的巨大需求,通过调研大量热物性测量方法研究文献,确定了基于瞬态接触热源法测量原理来实现防隔热材料的高温热物性测量;通过对该类测量方法文献资料的综述,总结归纳了目前存在的不足及实现热物性高温高精度测量所面临的主要问题;而后针对这些不足及问题,从理论、方法及关键技术等多层面、多角度地进行了深入的研究,并首次提出了一种能够综合考虑探头热容、时间延迟以及接触热阻等关键性影响因素的保护平面热源法;通过搭建基于该方法的隔热材料高温热物性测量装置,进行了一系列中常温测量实验研究、标定实验研究以及高温段测量的预先试验研究;通过实验研究,了解并考察了该方法所涉及的关键技术,从而为进一步实现高温高精度热物性测量提供了理论基础、经验借鉴及设备支撑。具体来说,所完成的主要创新性研究工作有:1.针对目前防隔热材料高温热物性测量时测温上限不足、没有充分考虑探头热容、时间延迟以及接触热阻等重要影响因素对热物性测量准确度的影响以及实际应用于中高温测量时准确度较差等方面的不足及问题,着重对接触热阻的产生机理及测量原理进行了较为深入的研究;通过设计特定的传热过程,首次将热物性测量与接触热阻的同步估计结合在了一起,提出了一种适合于隔热材料高温段热物性测试的保护平面热源法。通过对该传热过程进行理论建模,得到了能够综合考虑探头热容、时间延迟以及接触热阻影响的探头温升响应模型;为进一步考察接触热阻对热物性测量的影响规律、进一步提高热物性测量准确度提供了可能,同时也进一步完善了瞬态接触热源法的测量理论。2.研制了一套基于保护平面热源法的隔热材料高温热物性测量装置。装置中有很多巧妙的结构设计,其核心部件高温探头,既是薄片热源、又是高精度温度传感器、还具有保护加热功能,能够确保小尺寸试样测量时依然满足一维传热的假设条件;并能够胜任常温至高温(1500℃)的热物性测量,大大改善了目前测量温度上限不足的现状;探头及试样夹持器创新的结构设计能够减小并弥补试样边界的散热损失,从而严格保证了所需要的绝热边界条件;所研制的高真空管式黑体加热炉,能够提供稳定的高温测量条件、有效防止试样侧边界的对流热损失以及高温测试时的试样氧化问题,还能够满足不同压力下的热物性测量;经测试,该测量装置具有很好的稳定性和复现性。论文利用该装置实现了对VespelTM SP1标准材料多热物性及接触热阻的同时测量,测量结果通过与标准数据的比对,验证了保护平面热源法的正确性及准确度、还考察了所采用的多参数辨识方法、处理算法的实际使用性能;中常温范围内,热导率及热扩散率相对误差均小于6%,高温测量最大相对误差不超过10%;通过试验还发现了接触热阻对热物性测量所产生的影响及规律,保护平面热源法由于能够对接触热阻信息进行同步估计,因而对热导率及热扩散率在不同测量条件下的测量稳定性好,体现了保护平面热源法理论模型的完善;最后,分析了该装置的测量不确定度,确保了量值传递的准确性和可比性。3.基于所研制的高温隔热材料热物性测量装置和VespelTM SP1国际标准化材料完成了保护平面热源法应用于0.1～0.5W/mK热导率范围内的热物性测量准确度和实验参数的标定实验研究;了解了测试过程中试验参数的不同选择对热物性测量准确度的实际影响规律,提出了利用保护平面热源法进行热物性测试时的试验参数选取方法和依据,揭示了接触热阻对热物性测量所产生的影响及规律;另外,通过标定实验研究,还更进一步考察了保护平面热源法及其测试装置的测量准确度。更多还原

【Abstract】 This dissertation is a phasic research on“High temperature thermophysical properties measurement of thermal protective material”, which is suggested by Aerospace Research Institute of Materials and Processing Technology. The objective may be categorized as follows: (1) To develop a high precision thermal properties measuring technique and a practical measuring instrument used in high temperature; (2) To further improve the high-temperature thermal properties measuring standards; (3) To tentatively set up the first high-temperature thermophysical properties database; (4) To serve the development of new style thermal protective material; (5) To serve the design of thermal protective system and the development of national defence and spaceflight.Aim at the urgent demand of high-temperature thermal properties parameters of thermal protective material, the disseration focus on the contact transient plane source methods which are adopted extensively at present after a large amount of literature researching work. But untill now, there are still several weak points and subject problems existing which limit these methods applied to high-temperature and high-precision measurement. Based on such a situation, a new style, guarded plane source method for contemporary measuring thermal conductivity, thermal diffusivity and thermal contact resistance is presented through deep research work on measuring theory, method and key technology. In present work, the ambient temperature tests from room temperature up to 1200℃on two standardized material have been performed employing this method for the purpose of establishing the data processing procedure and recognizing the experimental troubles likely to be found. Particularly, the main creative research work are as follows:1. A new style method for high-temperature contact transient-measurements of thermal properties is presented, which is aiming at the present weak points and subject problems. Deep research work has been focused on the mechanism and transient measuring technique of contact thermal resistance, and the presented guarded plane source method can realize the contemporary thermal contact resistance estimation during the thermal conductivity and thermal diffusivity measurement through combining the transient measuring techniques of thermal properties and contact thermal resistance ingeniously. In comparison with other methods, the guarded plane source method can take into account thermal contact resistance in evaluating thermophysical properties which will greatly adds accuracy to the measuring results.2. A set of apparatus is designed and developed based on the principle of the new method. The high-temperature probe act both as film heater and high-accuracy temperature sensor, and can be applyed from room temperature to 1500℃. The employed structural design of the probe and the sample holder can reduce and remedy the side border heat loss of samples, and can guarantee the adiabatic conditions needed strictly. The developed high-vacuum and high-temperature tubular blackbody furnace can not only offer steady measuring condition, but also prevent the side border convection heat loss of samples and the oxidation problem while testing at high temperature. The simutaneous measurement of the contact thermal resistance and thermal properties is realized based on the the developed measuring apparatus and the standardized material VespelTM SP1. In the present work the experiment prove not only the exactness of the new method, but also recognize the data processing procedure and experimental troubles likely to be found. The results reported show a good capacity of determining both thermal properties and contact resistance, and the relationship between the measurement accuracy of thermal properties and the contact thermal resistance is revealed. It is possible to conclude that the method can give steady estimation results in different experimental conditions, which reflect the completion of the theory model. At last, a uncertainty analysis model is established, and the uncertanty evaluation can guarantee the accuracy and comparativity.3. The parameters standardization experiment of the new method is completed between thermal conductivity range of 0.1~0.5W/mK with the standardized material VespelTM SP1. It is confirmed experimentally that the relative error of thermal properties is sensitive to different choices of experimental parameters, and the standardization work is aiming at the improvement of measurement accuracy of thermal properties using the guarded plane source method. The effects analysis of different parameters selection on measuring-accuracy is investigated experimentally, and leads us to a conclusion of parameters choosing principle. At the same time, the measurement accuracy of the guarded plane source method is further investigated based on the standardiazation experiment.更多还原