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Friction and Wear Performance Evaluation of Bio-Lubricants and DLC Coatings on Cam/Tappet Interface of Internal Combustion Engines

The environmental concerns associated with artificially formulated engine oils have forced a shift towards bio-based lubricants. The deposition of hard coatings on engine components and migrating to environmentally friendly green lubricants can help in this regard. Chemically modified forms of veget...

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Autores principales: Zahid, Rehan, Bhutta, Muhammad Usman, Mufti, Riaz Ahmad, Abdullah, Muhammad Usman, Masjuki, Haji Hassan, Varman, Mahendra, Kalam, Muhammad Abul, Ali, Mian Ashfaq, Aslam, Jawad, Akhtar, Khalid
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8658346/
https://www.ncbi.nlm.nih.gov/pubmed/34885361
http://dx.doi.org/10.3390/ma14237206
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author Zahid, Rehan
Bhutta, Muhammad Usman
Mufti, Riaz Ahmad
Abdullah, Muhammad Usman
Masjuki, Haji Hassan
Varman, Mahendra
Kalam, Muhammad Abul
Ali, Mian Ashfaq
Aslam, Jawad
Akhtar, Khalid
author_facet Zahid, Rehan
Bhutta, Muhammad Usman
Mufti, Riaz Ahmad
Abdullah, Muhammad Usman
Masjuki, Haji Hassan
Varman, Mahendra
Kalam, Muhammad Abul
Ali, Mian Ashfaq
Aslam, Jawad
Akhtar, Khalid
author_sort Zahid, Rehan
collection PubMed
description The environmental concerns associated with artificially formulated engine oils have forced a shift towards bio-based lubricants. The deposition of hard coatings on engine components and migrating to environmentally friendly green lubricants can help in this regard. Chemically modified forms of vegetable oils, with better low-temperature characteristics and enhanced thermo-oxidative stability, are suitable substitutes to conventional lubricant base oils. The research presented in this manuscript was undertaken to experimentally investigate the wear and friction performance of a possible future generation of an environmentally friendly bio-based lubricant as a potential replacement for conventional engine lubricants. In order to quantify the tribological benefits which can be gained by the deposition of DLC coatings, (an (a-C:H) hydrogenated DLC coating and an (a-C:H:W) tungsten-doped DLC coating) were applied on the cam/tappet interface of a direct acting valve train assembly of an internal combustion engine. The tribological correlation between DLC-coated engine components, lubricant base oils and lubricant additives have been thoroughly investigated in this study using actual engine operating conditions. Two additive-free base oils (polyalphaolefines (PAO) and chemically-modified palm oil (TMP)) and two multi-additive-containing lubricants were used in this investigation. Real-time drive torque was measured to determine the friction force, detailed post-test analysis was performed, which involved the use of a specialized jig to measure camlobe wear. An optical profilometer was used to measure the wear on the tappet, high-resolution scanning electron microscopy was employed to study the wear mechanism and energy-dispersive X-ray spectroscopy was performed on the tested samples to qualitatively access the degradation of the coating. When using additive-free TMP, a low friction coefficient was observed for the cam/tappet interface. The presence of additives further improved the friction characteristics of TMP, resulting in reduced average friction torque values. A tremendous enhancement in wear performance was recorded with a-C:H-coated parts and the coating was able to withstand the test conditions with little or no delamination.
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spelling pubmed-86583462021-12-10 Friction and Wear Performance Evaluation of Bio-Lubricants and DLC Coatings on Cam/Tappet Interface of Internal Combustion Engines Zahid, Rehan Bhutta, Muhammad Usman Mufti, Riaz Ahmad Abdullah, Muhammad Usman Masjuki, Haji Hassan Varman, Mahendra Kalam, Muhammad Abul Ali, Mian Ashfaq Aslam, Jawad Akhtar, Khalid Materials (Basel) Article The environmental concerns associated with artificially formulated engine oils have forced a shift towards bio-based lubricants. The deposition of hard coatings on engine components and migrating to environmentally friendly green lubricants can help in this regard. Chemically modified forms of vegetable oils, with better low-temperature characteristics and enhanced thermo-oxidative stability, are suitable substitutes to conventional lubricant base oils. The research presented in this manuscript was undertaken to experimentally investigate the wear and friction performance of a possible future generation of an environmentally friendly bio-based lubricant as a potential replacement for conventional engine lubricants. In order to quantify the tribological benefits which can be gained by the deposition of DLC coatings, (an (a-C:H) hydrogenated DLC coating and an (a-C:H:W) tungsten-doped DLC coating) were applied on the cam/tappet interface of a direct acting valve train assembly of an internal combustion engine. The tribological correlation between DLC-coated engine components, lubricant base oils and lubricant additives have been thoroughly investigated in this study using actual engine operating conditions. Two additive-free base oils (polyalphaolefines (PAO) and chemically-modified palm oil (TMP)) and two multi-additive-containing lubricants were used in this investigation. Real-time drive torque was measured to determine the friction force, detailed post-test analysis was performed, which involved the use of a specialized jig to measure camlobe wear. An optical profilometer was used to measure the wear on the tappet, high-resolution scanning electron microscopy was employed to study the wear mechanism and energy-dispersive X-ray spectroscopy was performed on the tested samples to qualitatively access the degradation of the coating. When using additive-free TMP, a low friction coefficient was observed for the cam/tappet interface. The presence of additives further improved the friction characteristics of TMP, resulting in reduced average friction torque values. A tremendous enhancement in wear performance was recorded with a-C:H-coated parts and the coating was able to withstand the test conditions with little or no delamination. MDPI 2021-11-26 /pmc/articles/PMC8658346/ /pubmed/34885361 http://dx.doi.org/10.3390/ma14237206 Text en © 2021 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Zahid, Rehan
Bhutta, Muhammad Usman
Mufti, Riaz Ahmad
Abdullah, Muhammad Usman
Masjuki, Haji Hassan
Varman, Mahendra
Kalam, Muhammad Abul
Ali, Mian Ashfaq
Aslam, Jawad
Akhtar, Khalid
Friction and Wear Performance Evaluation of Bio-Lubricants and DLC Coatings on Cam/Tappet Interface of Internal Combustion Engines
title Friction and Wear Performance Evaluation of Bio-Lubricants and DLC Coatings on Cam/Tappet Interface of Internal Combustion Engines
title_full Friction and Wear Performance Evaluation of Bio-Lubricants and DLC Coatings on Cam/Tappet Interface of Internal Combustion Engines
title_fullStr Friction and Wear Performance Evaluation of Bio-Lubricants and DLC Coatings on Cam/Tappet Interface of Internal Combustion Engines
title_full_unstemmed Friction and Wear Performance Evaluation of Bio-Lubricants and DLC Coatings on Cam/Tappet Interface of Internal Combustion Engines
title_short Friction and Wear Performance Evaluation of Bio-Lubricants and DLC Coatings on Cam/Tappet Interface of Internal Combustion Engines
title_sort friction and wear performance evaluation of bio-lubricants and dlc coatings on cam/tappet interface of internal combustion engines
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8658346/
https://www.ncbi.nlm.nih.gov/pubmed/34885361
http://dx.doi.org/10.3390/ma14237206
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