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Study on the Improvement of Accuracy for the Measurement of Thermophysical Properties at High Temperature by a Singgle Rectangular Pulse Heating Method

单矩形脉冲加热法提高高温热物性测量精度的研究

基本信息

批准号：
61460109
负责人：
KOBAYASI Kiyosi
金额：
$ 4.03万
依托单位：
Toyota Technological Institute
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1986
资助国家：
日本
起止时间：
1986 至 1987
项目状态：
已结题

项目摘要

The information on thermophysical properties of new materials are required in vatious fields of industry. One of the authers presented a convenient measuring method of thermal conductivity and specific heat by a single rectanguar pulse heating. In this method, the thermal rdiation losses from all the surfaces of a finite disk specimen which is set in a vacuum high temperature furmace are taken into account. If the eemissivities are same on the all surfaces of the specimen, the rafiation heat loss increases with ambient temperature increase and decreases with thermal diffusivity and specific heat of the specimen increase. Therefore, if the measurement on a material having low thermal vonfuctivity as ceramics was carried out at high temerature tange, the rdiation loss will be large. So, the errors caused by uncertainty of the emissivity seem to be unavoidable. The obhjective of this study is to investigate the temperature dependence of the emissivity of the coatings on the specimen at high temperature up to 1600 k, and to improve the accuracy of the measurement.The technique of the emissivity measurement is based on comparing radiance from the specimen and a blackbody furnace keeping the same temperature. Four kinds of heat resisting coats were examined. It was found that no separation of coating from the specimen appeared and the temperature dependence was rather fiat in the 800-1600 k for SiC spray coating. Then, the thermal diffusivity and specific heat were measured on nickel and magnesia brick with SiC spray coating by the single rectangular pulse heating rechnigue. It was recognised that there were some differences between the present measuremeent recognized that there were some differences between the present measuremeent and the former one using carbon black coating, and improvement of the accuracy.

新材料的热物理性能信息在工业的各个领域都是必需的。本文介绍了一种用单次矩形脉冲加热测量导热系数和比热容的简便方法。该方法考虑了放置在真空高温炉中的有限圆盘试样的所有表面的热辐射损失。当试样各表面的发射率相同时，其气化热损失随环境温度的升高而增大，随试样的热扩散率和比热的升高而减小。因此，如果在高温范围内对陶瓷等低热导率材料进行测量，辐射损失将很大。因此，由发射率的不确定性引起的误差似乎是不可避免的。本研究的目的是研究在1600 K高温下涂层的发射率随温度的变化规律，以提高发射率测量的准确性。对四种耐热涂料进行了试验。结果表明，SiC喷涂层在800-1600 K范围内，涂层与试样无明显的分离现象，涂层的温度依赖性较平缓。然后，采用单矩形脉冲加热法测量了喷涂SiC涂层的镍砖和镁砖的热扩散率和比热。认为本测量方法与使用炭黑涂层的测量方法存在一定的差异，并提高了测量精度。