Thermophysical characteristics of friction materials based on bronze with 12% tin with the addition of GK-1 graphite powder and foundry coke

Abstract

The results of measurements of thermal properties in the temperature range from 20 °C to 100 °C of bronze with 12% tin obtained by powder metallurgy and 30 vol. % carbon-containing additive in the form of powders of graphite grade GK-1 (7-10 microns), foundry coke (less than 63 microns). The specific heat capacity of the samples was measured using the differential scanning calorimetry method. Thermal diffusivity and thermal conductivity were studied by two different methods. In the first case, the thermal diffusivity is determined by the laser flash method and the thermal conductivity by the calculation method. In the second case, the coefficients of thermal diffusivity and thermal conductivity were measured by the flat heat source method. It has been established that 30 vol.% of graphite powder GK-1 in the composition of bronze with 12% tin makes it possible to obtain the value of the thermal conductivity coefficient equal to 23,97 W/(m·K) at 20 °C with its further increase to 25,65 W/(m·K) at 100 °C. The specific heat capacity is 376,71 J/(kg·K) at 20°C and 399,26 J/(kg·K) at 100 °C. The addition of 30 vol.% coke powder makes it possible to obtain a thermal conductivity coefficient equal to 9,03 W/(m·K) at 20 ° C and 10,76 W/(m·K) at 100 °C. The specific heat capacity ranges from 391,80 J/(kg·K) at 20 °C to 413,57 J/(kg·K) at 100 °C