Improvement Effect of Green Lubricants on the Tribological and Mechanical Performance of 4140 Steel

Abstract

Although much has been learned and investigated about environmentally friendly lubricants in recent years, several issues remain critical to their use in specific applications. A key point that could be limiting their utilization is that the effect of green lubricants on the tribological and mechanical properties of the elements has not been thoroughly studied since such attributes determine their performance in industrial applications. For this reason, in this research, the effect of green lubrication on the tribological and hardness properties of AISI 4140 steel was studied. The performance of three bio-based lubricants was studied and compared to that of five of the most representative lubricants. First, the lubricants were chemically and physically characterized. Then, the effect of each lubricant on the friction and wear behavior of the system was analyzed by kinetic friction coefficient, wear rate calculations, and microhardness measurements. In general, the bio-based lubricants exhibited the lowest values of friction and wear. Further the mechanical properties of the systems lubricated by these lubricants were not affected or were affected to a lesser degree.

On the Tribological and Oxidation Study of Xanthophylls as Natural Additives in Castor Oil for Green Lubrication

“…Considering the impact of xanthophylls on the pressure–viscosity coefficient, a reduction of up to 50% was observed ( CO + 0.001 A ) concerning castor oil. The influence of viscosity and the pressure–viscosity coefficient on the creation of lubricant layers capable of supporting a load and protecting surfaces have been discussed previously [ 9 ].…”

“…Then, the viscosity index was calculated from the obtained viscosity values of bio-lubricants, according to the ASTM D 341 standard. Additionally, in order to have an estimation of the lubricant film thickness and the lubrication regime, the pressure–viscosity coefficient was evaluated from the bulk properties of the lubricants as per a reported procedure [ 9 ].…”

“…To define and comprehend the tribological properties of the new bio-lubricants, the film thicknesses and lubrication regimes were estimated. The methodology employed was based on the Hamrock and Dowson theory [ 20 ], following the method described in [ 9 ].…”

“…Furthermore, it is an inedible oil that is easy to produce, which does not affect the global oil production for human consumption and allows the use of arid areas for its cultivation [ 8 ]. Castor oil, without additives, has shown very low friction coefficients under most lubrication conditions [ 9 ], but when it operates in boundary lubrication, wear tends to increase [ 10 ]. Additionally, due to its triglyceride nature, it still has insufficient oxidative and thermal behavior, which limits its service life in storage and industrial applications.…”

Applied Research of Applicability of High-Strength Steel for a Track of a Demining Machine in Term of Its Tribological Properties

“…Nowadays, there are several methodologies of experimental wear assessment [4,[31][32][33][34]. The mechanical properties of the materials are closely related with the working environment.…”