Abstract This article presents a temperature-temperature thermal characterization method for the measurement of the thermal diffusivity of insulating materials at high temperature. This novel method, noted 4L, is a transient absolute measurement method based on the estimation of the transfer function at the center of a symmetrical stack composed of two specimen of an insulating material sandwiched between two conductive metallic plates. Two different direct 1D semi-analytical models were developed. The first one considers purely conductive opaque materials and the second one takes into account the coupling between radiative and conductive heat transfer modes for purely scattering semi-transparent materials. The first model was used to estimate the thermal diffusivity of two different opaque insulating materials (calcium silicate boards) up to 800 °C with accuracy better than 10%. The second model was used to estimate the thermal diffusivity of a semi-transparent insulating material (ceramic foam) up to 1000 °C with an accuracy of approximately 10%. The second model was used to identify significant estimation errors occurring if a purely conductive model is used for semi-transparent materials. The conducto-radiative model was also used to estimate an average value of the mean extinction coefficient of the semi-transparent material.

中文翻译：

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使用四层 (4L) 法测量高温绝缘材料的热扩散率

摘要 本文提出了一种用于测量绝缘材料在高温下的热扩散率的温-温热表征方法。这种新颖的方法（标为 4L）是一种瞬态绝对测量方法，它基于对由夹在两个导电金属板之间的两个绝缘材料样本组成的对称堆叠中心处的传递函数的估计。开发了两种不同的直接一维半解析模型。第一个考虑纯传导性不透明材料，第二个考虑纯散射半透明材料的辐射和传导传热模式之间的耦合。第一个模型用于估计两种不同的不透明绝缘材料（硅酸钙板）在高达 800 °C 时的热扩散率，精度优于 10%。第二个模型用于估计半透明绝缘材料（陶瓷泡沫）高达 1000 °C 的热扩散率，精度约为 10%。第二个模型用于识别在将纯导电模型用于半透明材料时发生的重大估计错误。传导辐射模型还用于估计半透明材料的平均消光系数的平均值。第二个模型用于识别在将纯导电模型用于半透明材料时发生的重大估计错误。传导辐射模型还用于估计半透明材料的平均消光系数的平均值。第二个模型用于识别在将纯导电模型用于半透明材料时发生的重大估计错误。传导辐射模型还用于估计半透明材料的平均消光系数的平均值。