Experimental study of the effect of silica nanoparticles on thermal and tribological properties of industrial lubricants

Lubrication is one of the most effective ways to reduce friction and reduce the excess heat generated in a mechanical system. Identifying the right additive to improve lubrication properties by additives that have features such as accessibility and higher quality performance is important. The aim of this study was to investigate the effect of silicon dioxide (SiO2) nanoparticles with different concentrations as additives on the thermal and anti-wear properties of lubricants. For this purpose, nanoparticles with concentrations of 0.2, 0.4 and 0.5 wt% were combined with oil. Span 80 surfactant, ultrasonic bath and high speed agitator were used to disperse the nanoparticles into the base fluid and achieve a stable nanofluid. The static stability of nanofluids was also visually investigated. The obtained results showed that the addition of nanoparticles to the oil does not cause any change in its state and over time no sedimentation and phase change was observed, which indicates the very good stability of this nanofluid. In the last stage, wear tests, determination of friction coefficient and thermal conductivity coefficient were performed on the samples. According to the results, the lowest amount of disc wear was related to the lubricating mixture with a concentration of 0.5% by weight. The weight loss of the discs due to wear for this mixture was 60.76%, the reduction of the coefficient of friction was 15.07% and the increase of the thermal conductivity was 2.4% compared to the base oil.