Skip to content

Dr Yong Sun

Job: Reader in Engineering Materials

Faculty: Technology

School/department: School of Engineering and Sustainable Development

Research group(s): Emerging Technologies Research Centre (EMTERC)

Address: De Montfort University, The Gateway, Leicester, LE1 9BH, United Kingdom

T: +44 (0)116 257 7072

E: ysun01@dmu.ac.uk

W: http://www.dmu.ac.uk

 

Research group affiliations

Emerging Technologies Research Centre (EMTERC)

Publications and outputs 

  • Effect of Applied Cathodic Potential on Friction and Wear Behavior of CoCrMo Alloy in NaCl Solution
    Effect of Applied Cathodic Potential on Friction and Wear Behavior of CoCrMo Alloy in NaCl Solution Sun, Yong; Bailey, Richard Most of the reported work on the effect of applied potential on tribocorrosion or corrosive wear of metallic alloys in a corrosive environment were conducted at anodic potentials. Limited tests have been conducted at cathodic potentials for comparison purposes or to derive the pure mechanical wear component in tribocorrosion. This work investigated the effect of cathodic potential on the friction and wear behaviour of an important biomedical alloy, CoCrMo, sliding against an Al2O3 slider in 0.9% NaCl solution at 37 C. High friction was found at cathodic potentials close to the open circuit potential, where mechanical wear played a predominant role in material removal. At potentials more cathodic than the hydrogen charging potential, low friction and low wear were observed. The coefficient of friction (COF) and total material loss decreased with increasing cathodic potential, such that at -1000 mV (saturated calomel electrode, SCE), extremely low COF values, as low as 0.02, and negligible material loss were obtained. Such reductions in friction and wear at increasing cathodic potentials were accompanied with the formation of parallel lines in the sliding track and were gradually diminished with increasing applied contact load. It is believed that hydrogen charging and hydrogen segregated layer formation at the surface are responsible for such a phenomenon. It can also be concluded that it is difficult to derive the pure mechanical wear component in tribocorrosion by simply conducting a test at an arbitrary cathodic potential. open access article
  • A comparative study of the tribocorrosion behaviour of low temperature nitrided austenitic and duplex stainless steels in NaCl solution
    A comparative study of the tribocorrosion behaviour of low temperature nitrided austenitic and duplex stainless steels in NaCl solution Haruman, E.; Sun, Yong; Adenan, M.S. This work studied and compared the tribocorrosion behaviour of low temperature nitridedaustenitic (316L) and duplex (2205) stainless steels. After gaseous nitriding at 450 �C for10 h, the S-phase layer formed on the duplex stainless steel is thicker and harder than that onthe austenitic stainless steel. The formation of S-phase layers reduces both mechanical wearand chemical wear of stainless steels but the duplex type exhibits better tribocorrosion performance. Wearing through of the S-phase layer during tribocorrosion leads to asignificant drop in open circuit potential, friction instability, and total material loss from the nitrided specimens. The work concludes that low temperature gaseous nitriding is effective in improving the tribocorrosion behaviour of these materials to avoiding catastrophic surface failures. 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.
  • Corrosive wear of multi-layer Fe-based coatings laser cladded from amorphous powders
    Corrosive wear of multi-layer Fe-based coatings laser cladded from amorphous powders Ji, Xiulin; Luo, Chanyuan; Sun, Yong; Zhao, Jianhua Since amorphous alloys exhibit good wear and corrosion resistance, they are supposed to be applied as a candidate implant material. In this work, using laser cladding, Multi-layer Fe-based alloy coatings were fabricated from amorphous powders on 316L stainless steel (SS) substrate. When the number of cladding layers increases, the microstructure of the coating was mainly composed of γ-Fe firstly, then evolved to γ-Fe and α-Fe solid solutions, and then to a composite of amorphous and crystalline phases. The surface hardness of the coating was also enhanced consequently to over 1200 HV. During reciprocate sliding against an Alumina ball in a simulated body fluid (Ringer’s solution), the volume loss and the coefficient of friction (COF) of the coatings generally decreased firstly and then increased with the number of cladding layers. During sliding at open circuit, the drop in open circuit potential (OCP) of all the Fe-based coatings, except for the 1-layer one, was not as significant as that of the 316 SS substrate. Moreover, when applying a cathodic potential during sliding, no obvious protective effect was obtained for the coatings, which indicates that the multi-layer Fe-based coatings possess a good corrosion-induced wear resistance in comparison to 316L SS. Because of the formation of an electric double layer, the fixed potential of 100 mVSCE or -600 mVSCE was beneficial to reduce the COF, especially for 316L SS. The tribocorrosion at OCP showed that the 2-layer coating possessed the best corrosive wear resistance, and its COF and volume loss were about 3 and 5.6 times lower than those of the substrate. The material loss in Ringer’s solution at OCP is mainly controlled by the mechanical wear for the coatings and the synergism between corrosion and wear for the substrate. Furthermore, this work provides a way to optimize the tribology system by adjusting the number of cladding layers to reduce COF and wear in a simulated body fluid. 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.
  • Surface finish and properties enhancement of selective laser melted 316L stainless steel by surface mechanical attrition treatment
    Surface finish and properties enhancement of selective laser melted 316L stainless steel by surface mechanical attrition treatment Sun, Yong; Bailey, Richard; Moroz, Adam Selective laser melting (SLM) has been used to produce stainless steel components with nearly full density, targeting real engineering applications. However, materials processed by SLM suffer from an inherent problem of poor surface finish, which is not suitable for many practical applications. It is thus necessary to improve the surface finish and surface integrity of SLM components through post processing. The aim of this work is to improve the surface finish of SLM 316L stainless steel by surface mechanical attrition treatment (SMAT), which involves bombarding the SLM sample surface with steel balls at a vibration frequency of 40 Hz for 10 min to 80 min. The surface finish, morphology, hardness and unlubricated sliding friction and wear behaviour were investigated. The results show that SMAT is very effective in smoothing the SLM 316L surface, reducing the surface roughness by up to 96% and achieving a surface finish comparable to that produced by surface grinding. SMAT also has the added benefits of increasing surface hardness, reducing friction and improving dry sliding wear resistance of SLM 316 L stainless steel. 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.
  • Surface finish effect on dry sliding wear behavior of thermally oxidized commercially pure zirconium
    Surface finish effect on dry sliding wear behavior of thermally oxidized commercially pure zirconium Alansari, A.; Sun, Yong The aim of this work was to investigate the effect of surface polishing on the wear behavior of thermally oxidized commercial pure zirconium (CP-Zr) under dry sliding conditions. Surface ground CP-Zr with a roughness of 0.21 m (Ra) was thermally oxidized (TO) at 650 °C for 6 h. After TO, some samples were polished to smoothen the surface with a finish of 0.04 m (Ra). The response of the polished and unpolished TO samples to dry sliding wear was investigated under unidirectional sliding conditions. The results show that surface polishing after TO affects the dry sliding wear behavior of TO CP-Zr in several aspects, including coefficient of friction, wear rate, crack formation and oxide layer breakdown. In particular, it is found that smoothening the TO surface favors the formation of semi-circular cracks in the wear track and accelerates oxide layer breakdown during dry sliding. A slightly rough TO surface helps to reduce the tendency of the oxide layer towards cracking and to increase the wear resistance at high contact loads. The mechanisms involved are discussed in terms of asperity contacts, crack formation, propagation and final fracture. 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.
  • Effect of sliding conditions on the macroscale lubricity of multilayer graphene coatings grown on nickel by CVD
    Effect of sliding conditions on the macroscale lubricity of multilayer graphene coatings grown on nickel by CVD Sun, Yong; Kandan, K.; Shivareddy, S.; Farukh, Farukh; Bailey, Richard A multilayer graphene (MLG) coating was grown on a nickel substrate by atmospheric chemical vapor deposition (CVD). The macroscale dry sliding friction behavior of the coated specimens against a stainless steel counterface was investigated under various contact loads ranging from 1 N to 5 N and at various rotational speeds from 30 rpm to 240 rpm. After the tests, the sliding surfaces were characterized by optical and scanning electron microscopes and Raman spectroscopy. The results show that contact load and sliding speed had significant effects on the lubricity of the MLG coatings under dry sliding conditions. At relatively low contact loads (1-3 N) and sliding speeds (30-120 rpm), the MLG coating exhibited good lubricity with coefficient of friction (COF) below 0.06 and lasted a long period of sliding time for more than 3600 cycles. With increasing contact loads and speeds, the COF of the MLG coating was gradually increased and the coating suffered from sudden breakdown after limited sliding cycles, losing its lubricity. Detailed examination and analysis revealed that material transfer occurred at the early stage of the sliding process, where MLG was transferred from the coating surface to the counterface. This graphene transfer was responsible for the lubricity of the sliding pair and the sustainability of the transferred material on the counterface determined the lifetime of the lubricity regime. High contact loads and high speeds favored severe plastic deformation and mechanical damages of the substrate, which limited the lifetime of the transferred material and thus the lifetime of the lubricity regime. Sliding induced defects in the MLG both on the coating and on the counterface were confirmed by Raman spectroscopy. 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.
  • Effect of Sliding Conditions on Micropitting Behaviour of AISI 304 Stainless Steel in Chloride Containing Solution
    Effect of Sliding Conditions on Micropitting Behaviour of AISI 304 Stainless Steel in Chloride Containing Solution Sun, Yong; Bailey, Richard The tribo-electrochemical behaviour of AISI 304 austenitic stainless steel in 0.5M NaCl solution is investigated at an anodic potential of 70 mV(SCE) under controlled sliding and electrochemical conditions. It is found that at such an anodic potential where corrosion pits do not form without sliding, numerous micro-pits are found inside the sliding tracks under certain sliding conditions. There exists a critical combination of frequency, load and sliding duration for the development of the pits. The results are discussed considering the accumulation of mechanical damages induced by sliding and the competition between wear and pit growth during the process. 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.
  • An Investigation into the Effects of Process Conditions on the Tribological Performance of Pack Carburized Titanium with Limited Oxygen Diffusion
    An Investigation into the Effects of Process Conditions on the Tribological Performance of Pack Carburized Titanium with Limited Oxygen Diffusion Bailey, Richard; Sun, Yong In the present study, a new pack carburization technique for titanium has been investigated. The aim of this treatment is to produce a titanium carbide/oxycarbide layer atop of an extended oxygen diffusion zone [α-Ti(O)]. The effects of treatment temperature and pack composition have been investigated in order to determine the optimal conditions required to grant the best tribological response. The resulting structural features were investigated with particular interest in the carbon and oxygen concentrations across the samples cross section. The optimization showed that a temperature of 925 °C with a pack composition of 1 part carbon to 1 part energizer produced surface capable of withstanding a contact pressure of ≈ 1.5 GPa for 1 h. The process resulted in TiC surface structure which offers enhanced hardness (2100 HV) and generates a low friction coefficient (μ ≈ 0.2) when in dry sliding contact with an alumina (Al O ) ball. 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.
  • Corrosion and Tribocorrosion Performance of Pack-Carburized Commercially Pure Titanium with Limited Oxygen Diffusion in a 0.9% NaCl Solution
    Corrosion and Tribocorrosion Performance of Pack-Carburized Commercially Pure Titanium with Limited Oxygen Diffusion in a 0.9% NaCl Solution Bailey, Richard; Sun, Yong In the research presented, the corrosion and tribocorrosion characteristics of pack carburized titanium with limited oxygen diffusion (PCOD-Ti) has been investigated using a 0.9 % NaCl solution. The carburization treatment was undertaken using a service temperature of 925 ℃ for duration of 20 h. The treatment resulted in the creation of a titanium carbide (TiC) network layer atop an extended oxygen diffusion zone (ODZ) (α-Ti(O)). Electrochemical testing indicated the treated titanium surface offered slightly enhanced corrosion resistance over that of untreated titanium. Tribocorrosion testing of the PCOD-Ti was conducted by sliding the titanium against an alumina counter-face under a contact load of 20 N, with various anodic and cathodic potentials applied. The testing showed a dramatic reduction in the wear rate for the treated titanium. Wear rates were reduced by an order of magnitude when compared with the untreated samples. During testing an interesting cathodic protection was encountered. When subjected to high negative charge the wear rates of the treated titanium were reduced further. This reduced wear was attributed to the formation of titanium hydride within the wear track. 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
  • A comparative study of the mechanical behaviour of thermally oxidized commercially pure titanium and zirconium
    A comparative study of the mechanical behaviour of thermally oxidized commercially pure titanium and zirconium Sun, Yong; Alansari, A. The objective of this study is to compare the mechanical behaviour of thermally oxidised commercially pure titanium (CP-Ti) and commercially pure zirconium (CP-Zr). For this purpose, these two bio-metals were thermally oxidised under the same condition (650 °C for 6 h) and the oxidised specimens were characterised using various analytical and experimental techniques, including oxygen uptake analysis, layer thickness and hardness measurements, scratch tests, dry sliding friction and wear tests and tribocorrosion tests in Ringer’s solution. The results show that under the present thermal oxidation condition, 4 times more oxygen is introduced into CP-Zr than into CP-Ti and the oxide layer produced on CP-Zr is nearly 6 times thicker than that on CP-Ti. Thermally oxidised CP-Zr possesses a higher hardness, a deeper hardening depth and better scratch resistance than thermally oxidised CP-Ti. Under dry sliding and tribocorrosion conditions, thermally oxidised CP-Zr also possesses much better resistance to material removal and a higher load bearing capacity than thermally oxidised CP-Ti. Thus, thermally oxidised Zr possesses much better mechanical behaviour than thermally oxidised Ti. 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.

Click here to view a full listing of Yong Sun's publications and outputs.

Research interests/expertise

Surface Engineering & Coating Technologies for Tribological, Corrosion Resistance and Biomedical Applications

Characterisation of Surface Engineered Systems.

Plasma Nitriding of Ferrous and Non-ferrous Alloys

Duplex Treatments

Magnetron Sputter Deposition of Oxide, Boride and Nitride Coatings

Surface Engineering of Stainless Steels

Surface Nanocrystalline Materials

Finite Element Analysis

Tribology and Corrosion of Coatings

Surface Engineering of Wear Components for Food Processing

Areas of teaching

Materials Science

Engineering Science

Failure Analysis

Materials and Sustainability

Green Design

Design for manufacturing

Solid Mechanics 

Qualifications

BSc, Ph.D

Courses taught

Mechanical Engineering BEng

Mechanical Engineering MSc

Green Energy Technologies BEng

Membership of professional associations and societies

Member of ASM International and Affiliated Heat Treatment Society

Conference attendance

The 8th International Conference on Plasma Surface Engineering AEPSE 2011: Invited Speaker and Session Chair, , Dalian, China, September 2011

Consultancy work

Area of expertise:

Surface treatments

Failure analysis

Materials selection

Previous consultations:

Generation 2 potato slicing blades: wear and failure analysis, Industrial consultant project for PepsiCo Inc., 2007

Surface treatments for potato slicing blades for improved lifespan, Industrial consultant project for PepsiCo Inc., 2008

Current research students

Mr. Richard Bailey: PhD student, First supervisor

Mr. Khalid Alrbaey: PhD student, Second supervisor

Internally funded research project information

DMU Research Capital Infrastructure Funding (RCIF): to develop the Materials Laboratory for teaching and surface engineering research, 2009

DMU Fee-only PhD scholarship Award: 2011

Published patents

Bell, Thomas and Sun, Yong: Process for the treatment of austenitic stainless steel articles

UK Patent ZSR455/Q036333PGB, 1997

United States Patent 6238490, May 29, 2001.

Professional esteem indicators

175 publications

Citation: total citations by others so far: more than 2000 times

Editorial board: Member of Editorial Board, (Journal) ISRN Materials Science, since January 2011

Service as reviewer for the following international journals:

  • Surface and Coatings Technology 
  • Surface Engineering 
  • Corrosion Science 
  • Journal of Materials Science 
  • Materials & Design 
  • Vacuum 
  • Materials Chemistry and Physics 
  • Journal of Physics and Chemistry of Solids 
  • Proceedings of the Institute of Mechanical Engineers 
  • Tribology International 
  • Tribology Letters 
  • Applied Surface Science 
  • Iranian Journal of Engineering 
  • Thin Solid Films

Search Who's Who