Thermal Management and Lubrication Characteristics of Tungsten Disulfide (WS2) Vegetable-Based Nanolubricants

Recent innovations with the aid of nanotechnology are more frequently seen in the industrial sectors. Lubricants are a high-end commodity resource used in many manufacturing processes; unfortunately, most of these lubricants are petroleum-based, which come with certain drawbacks, such as environmental aspects, handling issues and high costs. With the incorporation of nanostructures within fluids and lubricants, novel material alternatives are replacing conventional lubrication systems, maintaining the required thermophysical and tribological characteristics. This research provides an analysis of vegetable lubricant, castor oil (CO), and the effects of the incorporation of WS2 nanofiller at diverse filler fractions. A TEMPOS thermal analyzer device and a four-ball tribotester are used for the analysis of thermal conductivity and tribological assessments, respectively. Results showed the enhancement of thermal conductivity as the filler concentration and the evaluation temperature of the nanolubricants increased. The best thermal conductivity improvement was 27%, at 60 °C with merely 0.20 wt.% of nanofillers. For tribological performance, a decrease of 6% in the coefficient of friction (COF) and 31% in the wear scar diameter (WSD) was observed at 0.10 wt.% and 0.20 wt.%, respectively. Adhesion of the nanostructures to the steel surfaces creates a protective layer, preventing direct contact of the friction pairs. These results are an outcome of applied theoretical concepts such as Brownian motion and nano-layering of the lubricant–nanostructure interface.