Thermal-Diffusivity Measurement of Ceramic Coatings at High Temperature using "Front-Face" and "Rear-Face" Laser Flash Methods

Thick ceramic coatings deposited by plasma spraying techniques are widely used as wear and corrosion resistant coatings at high temperature. To measure accurately the thermal diffusivity of such coatings, the diffusivimeter of LNE has been set up to allow multilayered material studies up to 1,400A degrees C by rear-face and front-face laser flash methods. These two methods have been compared in a large temperature range by measuring the thermal diffusivity of homogeneous (Armco iron and Poco graphite) and multilayered materials (chromium oxide coating deposited on iron alloy substrate). The thermal-diffusivity values measured by using front-face and rear-face techniques are in good agreement, with a relative deviation of less than 5% depending on temperature and materials.