Feasibility Analysis of Biodegradable Automotive Lubricant: An Evaluation of Material–Lubricant Compatibility in a Corrosion Perspective

The material–lubricant compatibility is a crucial aspect to consider during the development of new bio-based automotive lubricants. The high-temperature corrosion tests provide an early idea about the compatibility between materials and lubricants. The present investigation aims to study the corrosiveness of newly formulated bio-lubricant as well as synthetic lubricant upon exposure to various automotive materials viz., cast iron, mild steel, copper, tin, zinc and lead using high-temperature corrosion test rig in accordance with ASTM D6594. At the end of the test, the impact of lubricant on corrosiveness of different materials was analysed by corrosion rate measurement and the corrosion effects on the metal specimens were examined by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction analysis. Furthermore, the tested lubricants were investigated using total acid number analyser, inductively coupled plasma spectroscopy and Fourier transform infrared spectroscopy to analyse the acid concentration of lubricants, corrosive wear metals and compositional change of lubricants, respectively. From the experimental study, it is found that for each tested material, bio-lubricant causes more corrosive attack than synthetic lubricant and also lead and copper are found to be more prone to corrosion.