Thermal Conductivity of Grade UPV-1 Pyrolytic Graphite at 1900–2950 K

Abstract

The need to account for a misalignment between the heat flux density and temperature gradient vectors when studying thermal conductivity of anisotropic materials was analyzed. A method for measuring thermal conductivity of pyrolytic graphite (grade UPV-1) in the direction parallel to the precipitation plane was proposed. The advantage of the proposed method is the possibility to determine thermal conductivity of pyrolytic graphite in the direction parallel to the precipitation plane while accounting for a misalignment between the heat flux density and temperature gradient vectors. The test samples were shaped as hollow cylinders with the pyrolytic graphite precipitation plane located along the radius of the cylinder. The heat flux density was determined based on the radiation heat flux emitted from the outer surface of the sample, and the temperature gradient was calculated along the radius, which made it possible to maintain the alignment between the heat flux density and temperature gradient vectors. A comparative analysis of the thermal conductivity values obtained in this study (parallel to the precipitation plane) and those reported in the reference sources was performed. The studied temperature range was extended into the higher temperature region by 450 K and constitutes 1900–2950 K.