University of Hertfordshire Research Archive

        JavaScript is disabled for your browser. Some features of this site may not work without it.

        Browse

        All of UHRABy Issue DateAuthorsTitlesThis CollectionBy Issue DateAuthorsTitles

        Arkivum Files

        My Downloads
        View Item 
        • UHRA Home
        • University of Hertfordshire
        • PhD Theses Collection
        • View Item
        • UHRA Home
        • University of Hertfordshire
        • PhD Theses Collection
        • View Item

        The Influence of Solid Additives on the Tribological Properties of Lubricants

        View/Open
        Download fulltext (PDF, 8Mb)
        Author
        Zhao, Chuanli
        Attention
        2299/11082
        Abstract
        The present work investigates the tribological properties of solid particles as lubricant additives in lubricants. Two types of solid particles, Ceria nanoparticles (CeO2) and Zinc borate ultrafine powders (ZB UFPs), were used as the lubricant additives in this study. The friction and wear behaviours of these lubricant additives in different base lubricants were identified. With an appropriate application of these solid lubricant additives, the friction reduction and wear resistance properties of the lubricant have been successfully improved. Without assistance of surfactant or surface modification, the two types of solid particles behave very differently. Evident performance was observed that pure ZB UFPs were capable of considerably reducing the friction coefficient of sunflower oil and liquid paraffin when they were used as a lubricant additive without further treatment. On the contrary, CeO2 nanoparticles did not show noticeable contribution to friction reduction when they were used as the only additive in water. Only when surfactant Sorbitan monostearate was employed to enhance the dispersibility of CeO2 nanoparticles in water, the application of this additive was capable of reducing friction coefficient of the water based lubricant effectively. Surface modification of the solid particles was carried out to improve the dispersibility of these particles in base lubricants. Oleic acid (OA) and Hexadecyltrimethoxysilane (HDTMOS) were selected as the modification agents. Modified CeO2 nanoparticles and ZB UFPs revealed outstanding wear resistance property. An improvement of up to 15 times was identified although this improvement on wear resistance, in this case, was often companied by a rise in friction coefficient. Tribo-films generated by tribo-chemical reaction were observed on most of the worn surfaces and the formation of this tribo-film appeared to have played an important role in the friction and wear behaviours of a system. A tenacious tribo-film with good surface coverage was only generated on the worn surface when HDTMOS modified solid particles were used as lubricant additives. The mechanical properties and elemental composition of the tribo-film were studied with nano-indentation and energy-dispersive X-ray spectroscopy (EDS). Finally, based on the experimental evidence, different functionalities of CeO2 nanoparticles and ZB UFPs as solid lubricant additives were recognized.
        Publication date
        2013-06-27
        Published version
        https://doi.org/10.18745/th.11082
        https://doi.org/10.18745/th.11082
        Other links
        http://hdl.handle.net/2299/11082
        Metadata
        Show full item record
        Keep in touch

        © 2019 University of Hertfordshire

        I want to...

        • Apply for a course
        • Download a Prospectus
        • Find a job at the University
        • Make a complaint
        • Contact the Press Office

        Go to...

        • Accommodation booking
        • Your student record
        • Bayfordbury
        • KASPAR
        • UH Arts

        The small print

        • Terms of use
        • Privacy and cookies
        • Criminal Finances Act 2017
        • Modern Slavery Act 2015
        • Sitemap

        Find/Contact us

        • T: +44 (0)1707 284000
        • E: ask@herts.ac.uk
        • Where to find us
        • Parking
        • hr
        • qaa
        • stonewall
        • AMBA
        • ECU Race Charter
        • disability confident
        • AthenaSwan