Simultaneous measurement of thermal conductivity and heat capacity by flash thermal imaging methods

Abstract

Thermal properties are important for material applications involved with temperature. Although many measurement methods are available, they may not be convenient to use or have not been demonstrated suitable for testing of a wide range of materials. To address this issue, we developed a new method for the nondestructive measurement of the thermal effusivity of bulk materials with uniform property. This method is based on the pulsed thermal imaging-multilayer analysis (PTI-MLA) method that has been commonly used for testing of coating materials. Because the test sample for PTI-MLA has to be in a two-layer configuration, we have found a commonly used commercial tape to construct such test samples with the tape as the first-layer material and the bulk material as the substrate. This method was evaluated for testing of six selected solid materials with a wide range of thermal properties covering most engineering materials. To determine both thermal conductivity and heat capacity, we also measured the thermal diffusivity of these six materials by the well-established flash method using the same experimental instruments with a different system setup. This paper provides a description of these methods, presents detailed experimental tests and data analyses, and discusses measurement results and their comparison with literature values.

Thermographic analysis of a Warring States sword

“…The peak's position is related to the thickness and thermal diffusivity of the first layer, and its amplitude is determined by the ratio of the effusivities of the two layers. By analyzing this curve, we can characterize the material characteristics of different layers [3].…”

Pulsed infrared thermographic study of a Chinese Bronze Lei

“…The peak ( 5) position is related to the thickness and thermal diffusivity of the first layer, and its amplitude is determined by the ratio of the effusivities of the two layers. By analyzing this curve, we can characterize the material characteristics of different layers [29]. When the second layer cannot be considered as semi-infinite, the peak amplitude and position will both depends on the properties of the second layer the logarithmic derivative will be larger than − 0.5, the value that describes a semi-infinite structure.…”

Ice accretion thickness prediction using flash infrared thermal imaging and BP neural networks

“…In addition, due to the high attenuation of the exponential term, the high‐order attenuation of the thermal wave may be ignored [27]. When thermally excited by flash lamps, the temperature of the ice surface will vary as follows [28]: $$$$\begin{equation}T\left( t \right) = {T}_0 + \frac{Q}{{e^{\prime}\sqrt {\pi t} }}\left[ {1 + 2\left( {\frac{{{{e^{\prime}} \mathord{\left/ {\vphantom {{e^{\prime}} e}} \right. \kern-\nulldelimiterspace} e} - 1}}{{{{e^{\prime}} \mathord{\left/ {\vphantom {{e^{\prime}} e}} \right.$$…”

“…In addition, due to the high attenuation of the exponential term, the high-order attenuation of the thermal wave may be ignored [27]. When thermally excited by flash lamps, the temperature of the ice surface will vary as follows [28]:…”