Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
Tribological evaluation of naphthenic base oils using four ball tester
Submission Author:
Paulo Roberto Campos Flexa Ribeiro Filho , MA
Co-Authors:
Denilson Monteiro, Adilto Cunha, Lourival Filho, Paulo Roberto Campos Flexa Ribeiro Filho
Presenter: Denilson Monteiro
doi://10.26678/ABCM.COBEM2023.COB2023-0517
Abstract
Base oils are the major components in the formulation of lubricants, representing 90% of the sample volume. Bases of mineral origin are classified according to the molecular structure of the hydrocarbon bonds in paraffinic, naphthenic and aromatic. Naphthenic oils are molecular structures of hydrogen and carbon atoms linked in a circular pattern. These oils are used as a basis for obtaining some mineral lubricants due to their good ability to solubilize additives and their low production cost. In addition, these bases have relevant physicochemical properties, with low pour points and high flash and combustion points, enabling them to be used as lubricants in a wide range of temperatures. Today, due to their improved thermal stability, these oils are used in the formulation of cutting oils, compressor oils and insulating oils. Despite all the advantages of physicochemical properties, the antifriction and antiwear capabilities have been little studied and in this way the study aims to investigate the tribological behavior of these samples. These capabilities are evaluated using tribological tests that simulate the operating conditions of lubricants, where analyzing the proper performance of the lubricant through high energy efficiency, low coefficients of friction (COF) and small wear scar diameter (WSD) are fundamental to certify safely the possibility of use in mechanical systems and equipment. In this study, the naphthenic-based lubricants NH-10 and NH-20 were evaluated through tribological tests in a tribometer in the configuration of four balls according to the ASTM D 4172 B standard. The NH-10 and NH-20 samples reached values of COF of 0.154 ± 0.012 and 0.143 ± 0.019 and WSD of 0.761 ± 0.010 mm and 0.842 ± 0.075 mm, respectively. Visual evaluations of the morphologies of wear scar lubricated with NH-10 and NH-20 indicate the presence of abrasive and adhesive wear mechanisms. According to the friction traces theory, which classifies the behavior of COF's under steady-state conditions, the curves obtained for NH-10 and NH-20 show type B behavior, where the COF gradually increases during the test. From a tribological point of view, this behavior enables the use of these naphthenic bases for the development of new lubricants.
Keywords
Naphthenic oils, Four ball tester, Tribology, ASTM D 4172 B
