Method and apparatus for measuring thermal constant using laser flash method

摘要

PURPOSE: To accurately and efficiently determine the thermal constants of an unknown layer in a multi-layer material by comparing the temperature response on the back face side obtained when a laser flash is radiated from the surface side of the multi- layer material and the theoretical temperature response including thermal diffusivity, specific heat, and Biot number as variables. ;CONSTITUTION: The temperature response on the back face side obtained when a laser pulse is radiated from the surface of a multi-layer material containing one layer having unknown thermal diffusivity () and specific heat (c) is fed to a computer. It is compared with the theoretical temperature response F(, c, h, t) or F'(, c, h, p) including the thermal diffusivity , specific heat (c), and Biot number (h) of the surface and back face of an unknown layer in the material set from documentary records as variables and calculated as a function of the time (t) or Laplace variable (p) of the temperature response. The thermal diffusivity , specific heat (c), and Biot number (h) are set when the deviation R between the functions E(t) and E'(p) using the time (t) and variable (p) of the actual temperature response as variables becomes the minimum deviation Rm, then the thermal constants such as the Biot number (h), specific heat (c), and thermal diffusivity of the unknown layer can be obtained.;COPYRIGHT: (C)1996,JPO