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Professor Yong Sun

Job: Professor

Faculty: Computing, Engineering and Media

School/department: School of Engineering and Sustainable Development

Research group(s): Solid Mechanics and Materials Research Group, Institute of Engineering Sciences

Address: 黑料网, The Gateway, Leicester, LE1 9BH, United Kingdom

T: +44 (0)116 257 7072

E: ysun01@dmu.ac.uk

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Research group affiliations

Solid Mechanics and Materials Research Group (Leader)

Institute of Engineering Sciences (IES)

Publications and outputs


  • dc.title: Effect of Counterbody Material on the Boundary Lubrication Behavior of Commercially Pure Titanium in a Motor Oil dc.contributor.author: Liu, Yizhao; Al-Shan, Mohammed; Bailey, Richard; Sun, Yong dc.description.abstract: Titanium possesses many useful properties and is a technologically important material in engi-neering. However, lubrication of titanium has long been a problem that has prevented titanium from being more widely used. This is due to its poor tribological properties deriving from its high tendency towards adhesive wear, material transfer and abrasive wear. Lubrication is a system engineering which involves material combinations, material surfaces, lubricants and operating conditions as a system. In this work, the boundary lubrication behavior of commercially pure tita-nium (CP-Ti) sliding against various counterbody materials in a motor oil (0W-30) was investigated under ball-on-plate reciprocating sliding conditions. The counterbody materials (balls) include CP-Ti, ceramic (Al2O3), steel (AISI 52100) and polymer (nylon). The results show that depending on material combination, the lubricating behavior can be divided into three categories, i.e. (1) lubri-cation failure (Ti-Ti), (2) improved lubrication but with friction instability (Ti-Al2O3), and (3) effec-tive lubrication (Ti-steel and Ti-nylon). Lubrication failure of the Ti-Ti pair leads to high and un-stable friction and severe wear from both the plate and ball, while friction instability of the Ti-Al2O3 pair leads to friction spikes and high wear rates. Effective lubrication of the Ti-steel pair results in low and smooth friction and much reduced wear rates of the Ti plate by nearly 10000 times. However, there is a load-dependence of the lubrication effectiveness of the Ti-steel pair. Although the Ti-nylon pair is effectively lubricated in terms of much reduced friction, the nylon ball suffers from severe wear. The friction and wear mechanisms of the various sliding pairs are discussed in this paper. dc.description: open access article

  • dc.title: Self-Reinforced Composite Materials: Frictional Analysis and Its Implications for Prosthetic Socket Design dc.contributor.author: Nagarajan, Yogeshvaran R.; Hewavidana, Yasasween; Demirci, Emrah; Sun, Yong; Farukh, Farukh; Kandan, Karthikeyan dc.description.abstract: Friction and wear characteristics play a critical role in the functionality and durability of prosthetic sockets, which are essential components in lower-limb prostheses. Traditionally, these sockets are manufactured from bulk polymers or composite materials reinforced with advanced carbon, glass, and Kevlar fibres. However, issues of accessibility, affordability, and sustainability remain, particularly in less-resourced regions. This study investigates the potential of self-reinforced polymer composites (SRPCs), including poly-lactic acid (PLA), polyethylene terephthalate (PET), glass fibre (GF), and carbon fibre (CF), as sustainable alternatives for socket manufacturing. The tribological behaviour of these self-reinforced polymers (SrPs) was evaluated through experimental friction tests, comparing their performance to commonly used materials like high-density polyethylene (HDPE) and polypropylene (PP). Under varying loads and rotational speeds, HDPE and PP exhibited lower coefficients of friction (COF) compared to SrPLA, SrPET, SrGF, and SrCF. SrPLA recorded the highest average COF of 0.45 at 5 N and 240 rpm, while SrPET demonstrated the lowest COF of 0.15 under the same conditions. Microscopic analysis revealed significant variations in wear depth, with SrPLA showing the most profound wear, followed by SrCF, SrGF, and SrPET. In all cases, debris from the reinforcement adhered to the steel ball surface, influencing the COF. While these findings are based on friction tests against steel, they provide valuable insights into the durability and wear resistance of SRPCs, a crucial consideration for socket applications. This study highlights the importance of tribological analysis for optimising prosthetic socket design, contributing to enhanced functionality and comfort for amputees. Further research, including friction testing with skin-contact scenarios, is necessary to fully understand the implications of these materials in real-world prosthetic applications. dc.description: open access article

  • dc.title: Laser Surface Engineering for Tribology dc.contributor.author: Ji, Xiulin; Sun, Yong dc.description.abstract: This book is a reprint of the Special Issue Laser Surface Engineering for Tribology that was published in Lubricants dc.description: Tribology grapples with diverse challenges, seeking to minimize friction and wear, and to advance the energy efficiency and sustainability of machinery. Laser surface engineering emerges as a highly effective solution with which to tackle these challenges. Recent advancements in this field, including techniques like laser texture, laser deposition, laser cladding, and laser modification, have found widespread applications in tribology. Surface-strengthening coatings, prepared via laser manufacturing, stand out as one of the most efficient strategies to mitigate tribological issues. The laser processing-related techniques either alter the surface texture or create a new film, thereby enhancing the mechanical, physical, and chemical properties of the contact surfaces. These innovations have seamlessly integrated into various industrial applications. This comprehensive reprint encompasses surface texturing, laser processing, and post-machining. Various metals, such as cast iron, steel, high-entropy alloy, and Ti-based, Cu-based, Al-based, and Ni-based alloys, are explored in this reprint, with a dedicated focus on leveraging laser surface engineering for tribological enhancements. In the pursuit of ongoing advancements in this field, contributors participate in this reprint, encompassing the domains of laser surface engineering and tribology, in order to delve into and share their insights. We anticipate that this reprint will draw attention to key research trends and state-of-the-art developments in laser surface engineering for tribology.

  • dc.title: Special issue on Laser surface engineering for tribology dc.contributor.author: Ji, Xiulin; Sun, Yong dc.description.abstract: This Special Issue compiles significant contributions addressing challenges in laser surface engineering for tribology, suggesting a future research focus on application-specific optimization. This involves tailoring laser surface engineering approaches to meet the diverse requirements of various industries, including automotive, aerospace, and manufacturing. Additionally, the utilization of advanced characterization techniques like in situ microscopy and spectroscopy is advantageous for a deeper understanding of dynamic changes in laser-modified surfaces during tribological testing. These proposed research directions aim to further advance laser surface engineering for tribological applications, tackling current challenges and enhancing the practical implementation of these techniques. dc.description: open access article

  • dc.title: Corrosive-wear performance of grade 316 stainless steel sliding against grade 316 stainless steel in NaCl solution dc.contributor.author: Bailey, Richard; Sun, Yong dc.description.abstract: Most of the reported corrosive-wear or tribocorrosion tests have been carried out using an inert and insulating counter-body in the experimental set up, with the purpose of eliminating the direct contribution of the counter-body to the electrochemical response during sliding wear. Little work has been reported using the same material as the test specimen and as the counter-body. In this work, corrosive-wear experiments have been carried out on the same material contact, i.e., stainless steel on stainless steel (SS-SS), where a 316 SS specimen was sliding against a 316 SS slider in 0.5 M NaCl solution under controlled electrochemical conditions. For comparison purpose, similar experiments have also been conducted on the 316 SS-Al2O3 sliding pair. The tests were conducted under reciprocating sliding conditions at 1 Hz frequency, 4 N load and for a duration of 7200 s, incorporated with electrochemical control which included potentiodynamic polarization and potentiostatic polarization at constant negative and positive potentials with respect to the open circuit potential (OCP). The results show that the counter-body has a large effect on the corrosive-wear behaviour of the 316 SS specimen under all test conditions. As compared to the SS-Al2O3 sliding pair, the SS-SS pair experiences larger material removal from the specimen. Adhesive wear occurs in the SS-SS pair which leads to significantly roughened sliding surfaces and unstable frictional behavior and electrochemical response. Further analysis revealed that mechanical wear plays a more dominant role in material removal in the SS-SS pair than in the SS-Al2O3 pair, and it is the corrosion-accelerated wear that contributes to the significantly increased material removal in the SS-SS pair. dc.description: The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.

  • dc.title: Effect of thermal oxidation on the dry sliding friction and wear behaviour of CP鈥慣i on CP鈥慣i tribopairs dc.contributor.author: Sun, Yong; Bailey, Richard; Zhang, Jin; Lian, Yong; Ji, Xiulin dc.description.abstract: Thermal oxidation (TO) has proven to be a cost-effective and efficient technique to engineer the surfaces of titanium and its alloys to achieve enhanced surface properties. The benefits of TO treatment in enhancing the tribological properties of titanium have been demonstrated by many investigators. However, most of the reported tribological studies have been based on the contact between a TO treated titanium specimen and a counter-body made of other materials, mainly ceramics, steels and polymers. Very few studies have been reported on the friction and wear behaviour of TO treated titanium sliding against TO treated titanium. In this work, the effect of thermal oxidation on the dry sliding friction and wear behaviour of commercially pure Ti (CP-Ti) on CP-Ti tribopairs was investigated under loading conditions ranging from elastic contact to plastic contact. Comparisons were made among three contact pairs: (1) untreated Ti on untreated Ti (Ti鈥揟i), (2) untreated Ti on TO treated Ti (Ti-TO) and (3) TO treated Ti on TO treated Ti (TO-TO). The results show that the TO-TO contact pair presents an ideal material combination to achieve the best tribological performance in terms of low friction and superior wear resistance. On the other hand, the Ti鈥揟i pair presents the worst combination in terms of tribological performance. While the Ti-TO pair performs better than the Ti鈥� Ti pair tribologically, it is not as good as the TO-TO pair. It is essential to thermally oxidize both specimens in order to achieve optimal tribological performance. It is the oxide layer-on-oxide layer contact that imparts the excellent tribological performance. Failure of the oxide layer in one of the contact bodies can lead to high and unstable friction and increased wear from both contacting bodies. The tribological performance of the three contact pairs and the failure mechanism of the oxide layer are discussed in the paper. The results of this work suggest that the TO treated Ti on TO treated Ti contact pair would have potential tribological applications in engineering. dc.description: open access article

  • dc.title: Surface Engineering & Coating Technologies for Corrosion and Tribocorrosion Resistance dc.contributor.author: Sun, Yong dc.description.abstract: The corrosion of materials leads to about 3 to 4% economic losses of GDP in an industrial nation and also significantly contributes to greenhouse emissions and climate change, as the production of materials is one of the largest greenhouse emitters. Corroded material replacement leads to increasing demands in materials production. Therefore, from economic and environmental points of view, it is highly necessary and important to enhance the corrosion and tribocorrosion resistance of materials. Since corrosion and tribocorrosion are surface- and subsurface-related material degradation phenomena, surface engineering and coating technologies are the most effective to tackle such problems. This reprint is a collection of the papers published in the Special Issue 鈥淪urface engineering & coatings technologies for corrosion and tribocorrosion resistance鈥� in the Materials journal. The Special Issue aims to collate the latest developments in this technologically, economically, and environmentally important area. It provides a forum for researchers to share their original work or insight reviews in this field. This reprint contains an Editorial by the Guest Editor and 12 original research papers and reviews related to this topic contributed by researchers from around the globe. The editor acknowledges the contributions of all the authors and the Editorial team in making this Special Issue a success dc.description: This is a reprint of articles from the Special Issue published online in the open access journal Materials (ISSN 1996-1944) (available at: www.mdpi.com/journal/materials/special_issues/Surface_ Tribocorrosion)

  • dc.title: Surface Engineering & Coating Technologies for Corrosion and Tribocorrosion Resistance dc.contributor.author: Sun, Yong dc.description: open access article

  • dc.title: Tribocorrosion Behavior of 纬鈥�-Fe4N Nitride Layer Formed on Mild Steel by Plasma Nitriding in Chloride-Containing Solution dc.contributor.author: Sun, Yong; Richard, Bailey dc.description.abstract: Nitriding has long been used to engineer the surfaces of engineering steels to improve their surface and subsurface properties. The role of the surface compound layer (飦р��-Fe4N and/or 飦�-Fe2-3N) in improving the tribological and corrosion resistant properties of nitrided steels has been established. However, there have been very few studies on the response of the compound layer to tribocorrosion in corrosive environments. In this work, the tribocorrosion behaviour of a 5 飦璵 thick 飦р��-Fe4N nitride layer produced on mild steel (MS) by plasma nitriding has been studied in a NaCl containing so-lution under various electrochemical conditions. The results show that at a cathodic potential of -700 mV (saturated calomel electrode, SCE), where mechanical wear is predominant, the total material removal (TMR) from the 飦р��-Fe4N layer is 37% smaller than that from the untreated MS, and at open circuit potential, TMR from the layer is 34% smaller than that from the untreated MS, while at an anodic potential of -200 (SCE), the 飦р��-Fe4N layer can reduce TMR from mild steel by 87%. The beneficial effect of the 飦р��-Fe4N nitride layer in improving the tribocorrosion behavior of mild steel is derived from its high hardness and good corrosion resistance in the test solution and its ability resist both mechanical wear and corrosion and to reduce wear-corrosion synergism. dc.description: open access article

  • dc.title: Comparison of wear performance of low temperature nitrided and carburized 316L stainless steel u