Tribological Compatibility of Diamond-like Carbon Coatings and Molybdenum Friction Modifiers in Engine Oil

Tribological Compatibility of Diamond-like Carbon Coatings and Molybdenum Friction Modifiers in Engine Oil | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Tribological Compatibility of Diamond-like Carbon Coatings and Molybdenum Friction Modifiers in Engine Oil Haipeng Huang, Yanyan Wang, Wen Yue This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8518371/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 7 You are reading this latest preprint version Abstract The synergistic integration of solid lubricants (e.g., diamond-like carbon, DLC) and oil-based friction modifiers (FMs) holds promise for enhancing engine fuel efficiency, yet their compatibility remains underexplored. This study investigates the tribological interactions between three DLC variants (a-C, a-C:H, ta-C) and molybdenum friction modifiers (MoFMs) in a Group III base oil and an SAE 0W-20 engine oil, along with the antagonistic/synergistic effects of zinc dialkyldithiophosphate (ZDDP)-MoFM blends. Friction and wear behaviors under boundary lubrication were evaluated using a ball-on-disc tribometer. Results reveal that both MoDTC and moly trimer decompose to form MoS 2 -rich tribofilms on steel and DLC surfaces, achieving significant friction reduction (up to 35%). However, MoDTC induces higher wear on amorphous DLCs (a-C and a-C:H) compared to moly trimer, attributed to accelerated graphitization. ZDDP forms protective phosphate films on DLCs, mitigating MoFM-induced wear, but its anti-wear performance is compromised by MoFM-derived sulfides. The combined use of ZDDP and MoFMs leads to mutual inhibition, diminishing their individual friction-reduction and anti-wear benefits. These findings highlight the necessity for tailored additive formulations when pairing DLC-coated components with MoFM containing lubricants, balancing friction optimization and durability in advanced engine systems. DLC MoDTC moly trimer ZDDP engine oil tribological properties Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 18 Feb, 2026 Reviews received at journal 17 Feb, 2026 Reviewers agreed at journal 20 Jan, 2026 Reviewers invited by journal 08 Jan, 2026 Editor assigned by journal 05 Jan, 2026 Submission checks completed at journal 05 Jan, 2026 First submitted to journal 05 Jan, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8518371","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":571775657,"identity":"db10c241-eca2-4c15-91ef-2f679f36aada","order_by":0,"name":"Haipeng Huang","email":"","orcid":"","institution":"Sinopec Lubricant Co., Ltd.","correspondingAuthor":false,"prefix":"","firstName":"Haipeng","middleName":"","lastName":"Huang","suffix":""},{"id":571775658,"identity":"c6f67787-8c3e-4999-9199-e9603090d522","order_by":1,"name":"Yanyan Wang","email":"","orcid":"","institution":"China University of Geosciences 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Oil","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"tribology-letters","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"tril","sideBox":"Learn more about [Tribology Letters](https://www.springer.com/journal/11249)","snPcode":"11249","submissionUrl":"https://submission.nature.com/new-submission/11249/3","title":"Tribology Letters","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"DLC, MoDTC, moly trimer, ZDDP, engine oil, tribological properties","lastPublishedDoi":"10.21203/rs.3.rs-8518371/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8518371/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe synergistic integration of solid lubricants (e.g., diamond-like carbon, DLC) and oil-based friction modifiers (FMs) holds promise for enhancing engine fuel efficiency, yet their compatibility remains underexplored. This study investigates the tribological interactions between three DLC variants (a-C, a-C:H, ta-C) and molybdenum friction modifiers (MoFMs) in a Group III base oil and an SAE 0W-20 engine oil, along with the antagonistic/synergistic effects of zinc dialkyldithiophosphate (ZDDP)-MoFM blends. Friction and wear behaviors under boundary lubrication were evaluated using a ball-on-disc tribometer. Results reveal that both MoDTC and moly trimer decompose to form MoS\u003csub\u003e2\u003c/sub\u003e-rich tribofilms on steel and DLC surfaces, achieving significant friction reduction (up to 35%). However, MoDTC induces higher wear on amorphous DLCs (a-C and a-C:H) compared to moly trimer, attributed to accelerated graphitization. ZDDP forms protective phosphate films on DLCs, mitigating MoFM-induced wear, but its anti-wear performance is compromised by MoFM-derived sulfides. The combined use of ZDDP and MoFMs leads to mutual inhibition, diminishing their individual friction-reduction and anti-wear benefits. These findings highlight the necessity for tailored additive formulations when pairing DLC-coated components with MoFM containing lubricants, balancing friction optimization and durability in advanced engine systems.\u003c/p\u003e","manuscriptTitle":"Tribological Compatibility of Diamond-like Carbon Coatings and Molybdenum Friction Modifiers in Engine Oil","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-01-12 15:20:49","doi":"10.21203/rs.3.rs-8518371/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-02-18T15:33:34+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-02-17T06:45:38+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"324949697155694000287471637179283287296","date":"2026-01-21T00:27:09+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-01-08T11:54:35+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-01-05T13:47:32+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-01-05T13:46:35+00:00","index":"","fulltext":""},{"type":"submitted","content":"Tribology Letters","date":"2026-01-05T07:38:27+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"tribology-letters","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"tril","sideBox":"Learn more about [Tribology Letters](https://www.springer.com/journal/11249)","snPcode":"11249","submissionUrl":"https://submission.nature.com/new-submission/11249/3","title":"Tribology Letters","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"fb7b169e-4e4f-4c13-9d9d-a217bb6ec162","owner":[],"postedDate":"January 12th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-04-01T14:23:33+00:00","versionOfRecord":[],"versionCreatedAt":"2026-01-12 15:20:49","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8518371","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8518371","identity":"rs-8518371","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}