Tribological Interaction of Plasma-Functionalized CaCO3 Nanoparticles with Zinc and Ashless Dithiophosphate Additives

• Published in: Tribology letters 2021-06, Vol.69 (2), Article 49
• Main Authors: Vyavhare, Kimaya, Timmons, Richard B., Erdemir, Ali, Aswath, Pranesh B.
• Format: Article
• Language: English
• Subjects: Additives; Atomic force microscopy; Automotive engines; Boundary lubrication; Calcium carbonate; Chemical reactions; Chemical synthesis; Chemistry and Materials Science; Comparative studies; Corrosion and Coatings; Formulations; Internal combustion engines; Low concentrations; Lubricants; Lubricants & lubrication; Lubrication; Materials Science; Morphology; Nanoparticles; Nanotechnology; Original Paper; Physical Chemistry; Plasma; Plasma enhanced chemical vapor deposition; Surfaces and Interfaces; Theoretical and Applied Mechanics; Thin Films; Tribology; Wear resistance; X ray absorption; Zinc
• ISSN: 1023-8883; 1573-2711
• DOI: 10.1007/s11249-021-01423-z

Surface-modified CaCO 3 nanoparticles, synthesized through plasma-enhanced chemical vapor deposition (PECVD), were employed to improve lubricant additive technology for internal combustion engines via reduction and/or replacement of additives, such as zinc dialkyl dithiophosphate (ZDDP), in engine oil. Various oil formulations were prepared with functionalized CaCO 3 nanoparticles, in combination with ashless dialkyl dithiophosphate (DDP) and ZDDP at low concentrations of phosphorus. Tribological test results indicate synergistic interaction of functionalized CaCO 3 nanoparticles with ZDDP and DDP, providing enhanced friction and wear performance under boundary lubrication. A comparative study of the tribo-surfaces morphology and chemistry was assessed via atomic force microscopy and X-ray absorption near-edge spectroscopy. Improved wear protection by functionalized CaCO 3 BM (borate and methacrylate coated) nanoparticles under boundary lubrication was attributed to the formation of calcium and boron-rich 50–80 nm thick tribofilms on the worn surfaces. XANES results revealed that plasma-functionalized CaCO 3 nanoparticles interact with ZDDP and DDP and participate in tribofilm formation through tribo-chemical reactions and metal cation supply to form stable and wear-resistant tribofilms. These results provide strong support for the potential application of plasma-functionalized CaCO 3 nano-additives to reduce the concentration of harmful P-based additives in automotive lubricants. Graphical Abstract