Investigation of thermal performances at addition metallic microparticles to greases used in outdoor environments

Two types of greases used to lubricate the moving parts of huge machines operating in external environments were selected to be examined thermal properties.Temperature, torque, absorbance properties and thermal conductivity coefficients of the greases with nonadditive and including additive (microparticles) were experimentally investigated. An experimental setup with one-hour controlled working period was prepared to examine of the temperature and torque changes. The radiative properties of the greases were examined in the UV-visible spectrum and the infrared wave length range of 2,5‒20 μm. The measurements of thermal conductivity were carried out in a conventional thermal conductivity measurement device in the temperature range of 20‒65 °C. CuO, TiO2, ZnO and graphite additives with high thermal conductivity properties were used and the measured absorption values of the samples were presented in graphics. The changing of temperature vary according to the type of greases. The Grease 2 reaches higher temperatures than the Grease 1. The temperature values of Grease 1 with microparticle additives are smaller than the values of Grease 1 without additives. For Grease 2, temperature changes of the samples with additives are higher than those values of Grease 2 without additives. In the infrared wave length range, for the greases of 0,02wt%,3,33 wt% and 10wt% microparticle-added, the absorption values of the samples are smaller than the samples without additives. In the absorption values of 10wt%additive Grease 1, the absorption results of the sample with graphite additive are significantly higher and in the absorption measurements of Grease 2, the sample with TiO2 additive receives high values at wave lengths after 12,5 μm. The thermal conductivity of Grease 1 with additives are smaller than those of Grease 1. For Grease 2, the added samples have higher thermal conductivities than those of Grease 2 without additive. The highest thermal conductivities were determined in Grease 2 with ZnO and the lowest thermal conductivity in Grease 2 with TiO2 samples. The torque values of the grease samples with additives are smaller than the values of the grease samples without additives.