Determination of the Local Thermal Conductivity of Functionally Graded Materials by a Laser Flash Method

Determination of thermal conductivity of construction materials is essential to estimate their insulation capabilities. In most cases, homogenous materials are used and well developed methods exist for measurements of their thermal conductivity. The task becomes more challenging when dealing with non-homogenous materials, where the properties are changing over the volume. In the present study a test procedure is presented to address this problem. The measurement is based on a transient laser flash technique, which is used to determine the local transport properties of heterogeneous samples by scanning them point by point and determining the thermal conductivity as a function of the spatial dimensions. The method proves to be repeatable and of reasonable accuracy and can be used to determine the local thermal properties on a scale of millimeters. In this study, the method was successfully applied to create a map of thermal conductivity of a functionally graded material sample.