PRECISE MEASUREMENTS OF THE SUPER-HIGH TERMAL CONDUCTIVITY COEFICIENT INTO THIN PLATES
The new method for measuring the thermal conductivity of polycrystalline diamond plates is developed. The method includes deposition of the two thin film full bridge resistance thermometers on the two opposite surfaces of the plate. The plate is heated from one side in area, where one of the resistance thermometers is located, by the contact with hot copper bar. The plate is cooled from the opposite side in area, where second of the resistance thermometers is located, by the contact with other copper bar that is cooled by the water. Heat flux that is flowing through the plate is measured with help of the thermocouples, that are installed on the hot copper bar, and is controlled by the automatic device. Thin film resistance thermometers, that are made by vacuum deposition, have thickness 50 nanometers and practically are the parts of the plate surfaces. For this reason the measured temperatures are exactly coinciding with temperatures on the two opposite surfaces of the plate. The high sensitivity of the thin film resistance thermometers is provided using their elevated electrical resistance value, that is permitting to have the bridge excitation not less than 20 V.