The influence of blackening in a laser spot periodic heating method and a laser flash method

Abstract

In a measurement of thermal property, to raise emissivity of sample surface is sometimes important. Blackening of the sample surface is a standard way to raise its emissivity for the measurement by a laser spot periodic heating method and a laser flash method. The blackening brings not only an increase of sensitivity but also an influence on the result of thermal property measurement, and then we should evaluate it in a quantitative way. In this research, thermal diffusivities of the four types of samples whose thickness of blackening layer are different were measured by periodic heating method and laser flash method. The relationship between apparent thermal diffusivity and thickness of blackening layer were obtained. Thicker the blackening layer is, lower the apparent thermal diffusivity is. The tendency of relationship between thickness of blackening layer and apparent thermal diffusivity are same in both of periodic heating method and laser flash method. Interfacial thermal resistance of samples is estimated by the comparison between experimentals and theoretical simulations of laser flash method.