Study On Thermal Diffusivity Of Isotropic Solid Materials By Laser Flash Measurement

Thermal diffusivity is used to characterize the specific properties of unsteady thermal conductive materials,combined with the specific heat capacity and bulk density,the thermal conductivity coefficients of homogeneous,dense and opaque solids can be calculated to understand the thermal conductivity characteristics of materials.Thermal conductivity is one of the most important attributes in the field of thermal design,heat utilization and energy problems,at the same time,thermal conductivity and thermal diffusivity,as heat transfer parameters,are very important for the analysis and study of unsteady processes,it is necessary to measure accurate thermal diffusivity.Using the standard device for measuring thermal diffusivity of solid materials by laser flash method from the Chinese Institute of Metrology,the thermal diffusivity of five Istropic Graphite samples with different thicknesses was measured at four temperature points of 300 K,600K,900 K,and 1200 K,participate in the comparison of thermal diffusivity organized by APMP,participating units of this comparison include Korea Research Institute of Standards and Science(KRISS),Laboratoire National de Métrologie et d'Essais(LNE),National Institute of Metrology China(NIM),Center for measurement Standards,Industrial Technology Research Institute(CMS/ITRI),National Physical Laboratory(NPL),National Metrology Institute of Japan(NMIJ).In order to achieve a higher-precision measurement of thermal diffusivity,it is proposed to improve the existing device.The main contents include: establishing an infrared measurement system,and designing a matching signal amplification system to achieve the measurement of thermal diffusivity in the temperature range of 300 K to1200K;designing a spot homogenization system to improve the uniformity of heating on the front surface of the sample,and establishing a mathematical model,Write the corresponding program to analyze and calculate the impact of non-uniform heating;use Python language to write a new data processing system.Use the newly established infrared test system to measure the non-metallic sample Isotropic Graphite provided by National Institute of Metrology.At 300 K,measurement is carried out by MCT detector and corresponding MCT amplifier;at600K,900 K,1200K,measurement is carried out by INSB detector and corresponding INSB amplifier.Finally according to the measurement results,analyze the source of uncertainty,give the uncertainty,and submit the measurement data to APMP T-S.9.