The Effect of Spherical Hybrid Silica–Molybdenum Disulfide on the Lubricating Characteristics of Castor Oil

Abstract

This investigation demonstrates the effect of a structural hybrid of spherical silica and lamellar molybdenum disulfide (MoS2) combined to form a sphere used as an antifriction and antiwear additive in vegetable oil in steel-on-steel tribopair. Hybrids demonstrated improved dispersion stability due to the deposition of lightweight silica on the surface of hydrothermally prepared 2D sheets of MoS2. The concentration of nanohybrid was optimized for optimal lubricant performance, and the best region of test space is presented in this work. At the optimum concentration, the coefficient of friction (COF) was 0.03236, with an average wear volume of 2.16 × 10−12 m3. The synergism of the particles significantly reduces friction and wear. The collision of the hybrid spheres with the surface has an immediate effect on it. The broken sphere of wear debris was observed under scanning electron microscopy. The wear debris analysis indicates that the lubrication mechanism begins with the rolling of hybrid spheres and ends with the rolling and sliding of silica and MoS2.