Measurement of Thermal Diffusivity in Principal Direction of Orthotropy Material by a Step Heating Method

Carbon fiber reinforced carbon composites (C/C composites) have been important structural materials at high temperatures. C/C composites are anisotropic solids and their thermal diffusivity is the second-order tensor of which components are called thermal diffusivity coefficients. Therefore, the purpose of study is to measure the thermal diffusivity in direction parallel to fiber and that in direction perpendicular to fiber by using the step heating method. This report demonstrates the correctness of the method to determine the thermal diffusivity in principal direction by comparing the time change of temperature observed by the experiment at room temperature for the C/C composite with the mathematical solution for the heat conduction under one dimension.