Yu Yan

Publications

• 0.95

  Impact points

  Electrochemical instrumentation of a hip simulator: a new tool for assessing the role of corrosion in metal-on-metal hip joints.

  Y Yan, A Neville, D Dowson, S Williams, J Fisher

  Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine. 11/2010; 224(11):1267-73.

  Polyethylene wear debris induced osteolysis has triggered investigations to find alternative material combinations to the well-established metal-on-polyethylene hip implants. Owing to some early successful clinical cases, metal-on-metal (MoM) hip replacements have been attracting more and more inter... [more] Polyethylene wear debris induced osteolysis has triggered investigations to find alternative material combinations to the well-established metal-on-polyethylene hip implants. Owing to some early successful clinical cases, metal-on-metal (MoM) hip replacements have been attracting more and more interest. There is, however, considerable concern about the propensity of MoM hip replacements to release metal ions and fine, nanometre-scale metallic wear debris. The long-term effect from released metal ions and wear particles is still not clear. To date, all the work on hip simulators focused on assessing mass losses damage has been referred to as 'wear'. However, it is known in the field of tribocorrosion that mechanical removal of the passive layer on Co-Cr alloys can significantly enhance corrosion activity. In total joint replacements, it is possible that corrosion plays a significant role. However, no one has ever tried to extract, on a hip simulator, what proportion of the damage is due to mechanical processes and the corrosion processes. This paper describes the first instrumentation of an integrated hip joint simulator to provide in-situ electrochemical measurements in real time. The open circuit potential results are reported to assess the corrosion regime in the absence and presence of movement at the bearing surfaces. The importance of these measurements is that the real damage mechanisms can be assessed as a function of the operating cycle.
• 0.95

  Impact points

  Understanding the differences between the wear of metal-on-metal and ceramic-on-metal total hip replacements.

  C G Figueiredo-Pina, Y Yan, A. Neville, J Fisher

  Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine. 05/2008; 222(3):285-96.

  Hip simulator studies have been carried out extensively to understand and test artificial hip implants in vitro as an efficient alternative to obtaining long-term results in vivo. Recent studies have shown that a ceramic-on-metal material combination lowers the wear by up to 100 times in comparison ... [more] Hip simulator studies have been carried out extensively to understand and test artificial hip implants in vitro as an efficient alternative to obtaining long-term results in vivo. Recent studies have shown that a ceramic-on-metal material combination lowers the wear by up to 100 times in comparison with a typical metal-on-metal design. The reason for this reduction remains unclear and for this reason this study has undertaken simple tribometer tests to understand the fundamental material loss mechanisms in two material combinations: metal-on-metal and ceramic-on-ceramic. A simple-configuration reciprocating pin-on-plate wear study was performed under open-circuit potential (OCP) and with applied cathodic protection (CP) in a serum solution using two tribological couples: firstly, cobalt-chromium (Co-Cr) pins against Co-Cr plates; secondly, Co-Cr pins against alumina (Al2O3) plates. The pin and plate surfaces prior to and after testing were examined by profilometry and scanning electron microscopy. The results showed a marked reduction in wear when CP was applied, indicating that total material degradation under the OCP condition was attributed to corrosion processes. The substitution of the Co-Cr pin with an Al2O3 plate also resulted in a dramatic reduction in wear, probably due to the reduction in the corrosion-wear interactions between the tribological pair.

• Tribo-corrosion analysis of wear and metal ion release interactions from Metal-on-Metal and Metal-on-Ceramic contacts for the application of artificial prostheses

  Yu Yan, Anne Neville, Duncan Dowson, Sophie Williams, John Fisher

  Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology. 05/2008; 22:483-492.

• Biotribocorrosion of CoCrMo orthopaedic implant materials

  Yu Yan, Anne Neville, Duncan Dowson

  Tribology International. 12/2007; 40:1492-1497.

• Synovial joint lubrication – does nature teach more effective engineering lubrication?

  Anne Neville, Ardian Morina, Tomasz Liskiewicz, Yu Yan

  Proceedings of the Institution of Mechanical Engineers, Part C: Mechanical Engineering. 12/2007; 221:1223-1230.

• Tribo-corrosion properties of Cobalt-based medical implant alloys in simulated biological environments

  Yu Yan, Anne Neville, Duncan Dowson

  Wear. 12/2007; 263:1105-1111.

• Tribocorrosion in implants—assessing high carbon and low carbon Co–Cr–Mo alloys by in situ electrochemical measurements

  Yu Yan, Anne Neville, Duncan Dowson, Sophie Williams

  Tribology International. 12/2006; 39:1509-1517.

• Corrosin and Tribocorrosion behaviour of metallic materials in artificial joint implants

  Yu Yan

  09/2006

  Degree: PhD

  Supervisor: Prof. Anne Neville

• Biotribocorrosion – an appraisal of the time dependence of wear and corrosion interactions Part II: Surface analysis

  Yu Yan, Anne Neville, Duncan Dowson

  Journal of Physics D: Applied Physics. 05/2006; 39:3206-3212.

• Biotribocorrosion – an appraisal of the time dependence of wear and corrosion interactions Part I: The role of corrosion

  Yu Yan, Anne Neville, Duncan Dowson

  Journal of Physics D: Applied Physics. 05/2006; 39:3200-3205.
• 0.95

  Impact points

  Understanding the role of corrosion in the degradation of metal-on-metal implants.

  Y Yan, A. Neville, D Dowson

  Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine. 03/2006; 220(2):173-81.

  In metal-on-metal joints the primary concerns in terms of long-term durability relate to corrosion, wear, and their joint (tribocorrosion) effects. The release of ions through corrosion processes and nanoscale debris from wear processes can seriously affect joint integrity and can lead to an adverse... [more] In metal-on-metal joints the primary concerns in terms of long-term durability relate to corrosion, wear, and their joint (tribocorrosion) effects. The release of ions through corrosion processes and nanoscale debris from wear processes can seriously affect joint integrity and can lead to an adverse biological reaction by the host. In this paper an integrated study of corrosion-wear interactions in serum, Dulbecco's Modified Eagle's Medium and 0.3 per cent NaCl has demonstrated that the biological nature of the fluid affects the total degradation rate and also the level of wear-corrosion interactions. The specific action of proteins in corrosion and tribocorrosion for high-carbon Co-Cr-Mo and low-carbon Co-Cr-Mo alloys is discussed.

• Tribo-corrosion properties of cobalt-based medical implant alloys in simulated biological environments

  Y Yan, A. Neville, D Dowson

  Tribological problems and corrosion degradation have been recognized as essential risks for total joint replacements, especially for all-metal arthroplasty. Few studies have focused on the interactions between tribology and corrosion (tribocorrosion) for implant materials. This paper addresses the i... [more] Tribological problems and corrosion degradation have been recognized as essential risks for total joint replacements, especially for all-metal arthroplasty. Few studies have focused on the interactions between tribology and corrosion (tribocorrosion) for implant materials. This paper addresses the importance of understanding tribocorrosion and the evaluation of such materials in simulated biological environments. Due to the complex effect of proteins on tribocorrosion, which has been demonstrated in previous studies, this study focuses towards understanding the effects of amino acids as aspects of material degradation. Dulbecco’s Modified Eagle’s Medium (DMEM) is a cell culture solution. It contains comparable amount and types of amino acids to normal synovial fluid in human joints. 0.36% NaCl solution was employed to isolate the biological species. Three materials were tested; High carbon (HC) CoCrMo (contains 0.19% carbon), low carbon (LC) CoCrMo (widely used materials for total joint replacement) and stainless steel UNS S31603 (316L). Integrated electrochemical tests supported by measurement of friction and near surface chemical analysis were carried out to enable their tribocorrosion behaviour to be fully characterized. As a general conclusion, amino acids were found to react with materials under tribological contacts and form complex organometallic/oxides which lubricate the metallic sample surface. Tribocorrosion plays a very important role in material degradation in the studied environments. HC CoCrMo shows superior wear, corrosion and tribocorrosion resistance – the material characteristics and their effect on the different tribocorrosion processes are discussed.

• Synovial joint lubrication – does nature teach more effective engineering lubrication strategies?

  A. Neville, A. Morina, T. Liskiewicz, Y Yan

  Nature shows numerous examples of systems which show energy efficiency, elegance in their design and optimum use of materials. Biomimetics is an emerging field of research in engineering and successes have been documented in the diverse fields of robotics, mechanics, materials engineering and many m... [more] Nature shows numerous examples of systems which show energy efficiency, elegance in their design and optimum use of materials. Biomimetics is an emerging field of research in engineering and successes have been documented in the diverse fields of robotics, mechanics, materials engineering and many more. To date little biomimetics research has been directed towards tribology in terms of transferring technologies from biological systems into engineering applications. The potential for biomimicry has been recognised in terms of replicating natural lubricants but this system reviews the potential for mimicking the synovial joint as an efficient and durable tribological system for potential engineering systems. The use of materials and the integration of materials technology and fluid/surface interactions are central to the discussion.

• Biotribocorrosion of CoCrMo orthopaedic implant materials—Assessing the formation and effect of the biofilm

  Yu Yan, Anne Neville, Duncan Dowson

  Tribology International.

  Due to the renewed interest in hard-on-hard hip replacement, especially metal-on-metal (MoM) or metal-on-ceramic (MoC) joints, issues relating to their long-term durability need to be addressed. Their effects on the operating environment (human body) and how the body fluid affects the implant materi... [more] Due to the renewed interest in hard-on-hard hip replacement, especially metal-on-metal (MoM) or metal-on-ceramic (MoC) joints, issues relating to their long-term durability need to be addressed. Their effects on the operating environment (human body) and how the body fluid affects the implant materials are the primary concern. For widely used metallic implant materials, such as cobalt–chromium–molybdenum (CoCrMo) alloys, released ions due to electrochemical (corrosion) processes and mechanical-enhanced electrochemical (corrosion-wear/tribocorrosion) processes may cause biological reactions in the human hosts. Proteins are a primary constituent of the synovial fluid in human joints with other organic components such as hyaluronic acid and lubricin, and, although numerous tribological studies in protein-containing fluids have been conducted, there is still a need to fully understand the role of proteins and adsorbed-protein layers in wear, corrosion and tribocorrosion processes in artificial joints.In this study, bovine calf serum was used to simulate the body fluid, and a model solution of 0.36% NaCl solution was employed to isolate the influence of organic species (such as proteins, amino acids etc.). Wrought high carbon cobalt–chromium–molybdenum alloy (HC CoCrMo), Wrought low carbon cobalt–chromium–molybdenum alloy (LC CoCrMo) and stainless steel UNS S31603 (316 L) were included in the study and their corrosion, tribology and tribocorrosion behaviour were assessed by integration of gravimetric analysis and electrochemical measurements. Surface analysis (chemical and topographical) was carried out to fully understand the surface/organic species interactions.The constituents of bovine serum have been shown to have a great influence on the corrosion behaviour of all materials studied here—the mechanism of their action being to accelerate ion release and passive film breakdown in static conditions. In tribological contacts, biofilm can play a role in forming an effective lubricating film that reduces friction. For HC CoCrMo, reactions at the surface in the contact zone form a very complex nanostructured layer which comprises wear debris, biofilm and reaction products and the process also changes the nature of the passive film formation. The film reduces the material loss and hence has a protective nature. Organic species (proteins, etc.) were also shown to enhance corrosion-related damage on all materials.

• Tribo-corrosion properties of cobalt-based medical implant alloys in simulated biological environments

  Yu Yan, Anne Neville, Duncan Dowson

  Wear.

  Tribological problems and corrosion degradation have been recognized as essential risks for total joint replacements, especially for all-metal arthroplasty. Few studies have focused on the interactions between tribology and corrosion (tribo-corrosion) for implant materials. This paper addresses the ... [more] Tribological problems and corrosion degradation have been recognized as essential risks for total joint replacements, especially for all-metal arthroplasty. Few studies have focused on the interactions between tribology and corrosion (tribo-corrosion) for implant materials. This paper addresses the importance of understanding tribo-corrosion and the evaluation of such materials in simulated biological environments. Due to the complex effect of proteins on tribo-corrosion, which has been demonstrated in previous studies, this study focuses towards understanding the effects of amino acids as aspects of material degradation. Dulbecco's Modified Eagle's Medium (DMEM) is a cell culture solution. It contains comparable amount and types of amino acids to normal synovial fluid in human joints. NaCl (0.36%) solution was employed to isolate the biological species. Three materials were tested: high carbon (HC) CoCrMo (contains 0.19% carbon), low carbon (LC) CoCrMo (widely used materials for total joint replacement) and stainless steel UNS S31603 (316 L). Integrated electrochemical tests supported by measurement of friction and near surface chemical analysis were carried out to enable their tribo-corrosion behaviour to be fully characterized. As a general conclusion, amino acids were found to react with materials under tribological contacts and form complex organometallic/oxides which lubricate the metallic sample surface. Tribo-corrosion plays a very important role in material degradation in the studied environments. HC CoCrMo shows superior wear, corrosion and tribo-corrosion resistance—the material characteristics and their effect on the different tribo-corrosion processes are discussed.