Determination of Thermal Diffusivity/conductivity of Oxide Scale Formed on Steel Plate by Laser Flash Method through Thermal Effusivity Measurement by Transient Hot-strip Method

Abstract

Thermal diffusivity and conductivity were determined for oxide scale formed on steel plate by the laser flash method in combination with thermal effusivity measurement by the transient hot-strip method. The thermal effusivity measurement technique was confirmed by measurement of silica glass, and the value was determined to be 2.52 kJ m⁻² s^−1/2 K⁻¹ for the oxide scale formed on an ultra-low-carbon steel plate by oxidation in air at 900°C for 3600 s. Thermal diffusivity measurements were also conducted for 1 mm-thick steel plates oxidized in air at 900°C for 770–3600 s by the laser flash method. The apparent thermal diffusivity of samples provided the thermal diffusivity of the oxide scale based on three-layered analysis by inputting the measured value of the thermal effusivity. The measured values suggested that no significant boundary resistance exists between the oxide scale and the steel plate. The thermal conductivity and diffusivity of the oxide scale were calculated to be 1.6 W m⁻¹ K⁻¹ and 4.0 × 10⁻⁷ m² s⁻¹, respectively.