Characterization and nano-mechanical properties of tribofilms using Cu nanoparticles as additives

• Published in: Surface & coatings technology 2008-10, Vol.203 (1), p.28-34
• Main Authors: Yu, H.L., Xu, Y., Shi, P.J., Xu, B.S., Wang, X.L., Liu, Q., Wang, H.M.
• Format: Article
• Language: English
• Subjects: Applied sciences; Copper film; Cross-disciplinary physics: materials science; rheology; Cu nanoparticles; Exact sciences and technology; Materials science; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Nano-indentation; Physics; Surface treatments; Tribological property
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2008.07.032

Cu nanoparticles were dispersed into SN 650 oil to improve the lubricating properties of the oil and in-situ generate a thin copper film on the rough steel surface in the process of sliding friction. SEM, XPS and nano-indentation tester were utilized to investigate the morphology, chemical state and nano-mechanical properties of the film, respectively. Results show that the friction-reducing and anti-wear properties of SN 650 oil have been improved by adding Cu nanoparticles. A metallic copper film, with a low hardness and a thickness of approximately 5 μm, has been formed on the worn steel surface under the lubrication of SN 650 oil containing 1 wt.% Cu nanoparticles. The film, which bonds well with the substrate steel by a metallurgical bonding, separates the two contact surfaces and provides a fast relaxation of the contact stress. An ideal tribological structure with a soft surface film and a hard sub-surface has been formed on the worn surface, which was considered as the main reason why Cu nanoparticles possessed the excellent tribological properties.