Experimental Analysis of Chemically Degraded Lubricant’s Impact on Spur Gear Wear

Abstract

The impact of lubricating oil degradation, which can happen during both storage and use, on spur gear wear is thoroughly examined in this paper at all scales, from macro to nano. A thorough structure was created by combining the results of testing performed at the macroscale on a test rig and at the nanoscale using tools such as FESEM analysis. Using a single-stage spur transmission under two different working conditions (‘40 Nm, 1200 rpm, 198 h’ and ‘50 Nm, 500 rpm, 90 min’), macroscale experiments were carried out using both conventional and artificially degraded lubricant oils. Aqueous hydrochloric acid (36.46% v/v concentration) was added to the lubricating lubricant to induce artificial degradation. Wear development and oil degradation were monitored in real time using tools such as metallic wear detritus sensors and oil sensor suites. Offline methods, such as total acid number (TAN) and pH value readings, were used with periodic lubricant oil samples. It was discovered through both online and offline monitoring methods that the spur gear experienced substantial wear in lubricant-degraded conditions. By demonstrating elevated levels of oxidative degradation products and the formation of new oxidative compounds, such as sulphates and aromatic groups, the attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) analysis of the oil degradation at the nanoscale verified this. In addition, water creation was noted. It is interesting to note that the pH meter has become a viable option for detecting oil degradation and offers a useful way to keep track of lubricant quality. Overall, this study shows that there is a strong connection between macroscale and nanoscale phenomena in the complete method created for assessing the tribological performance of gear lubricants.

Keywords

• lubricant degradation
• additive depletion
• pH value
• TAN value
• wear
• ATR-FTIR