Development of high performance tribological coatings for application onto hip joint prostheses

2.50
Hdl Handle:
http://hdl.handle.net/2436/94223
Title:
Development of high performance tribological coatings for application onto hip joint prostheses
Authors:
Knox, Paul
Abstract:
In this thesis Graphit-iC™, an amorphous carbon coating developed by Teer Coatings Ltd. was modified and deposited onto CoCr and WHMWPE substrates in order to improve the wear properties. It was identified that depositing a hard coating onto soft substrate would cause high stresses and lead to coating delamination. Consequently the polyethylene substrates were ion implanted with nitrogen to reduce the hardness differential at the substrate-coating boundary. The coating was characterised using a pin on disc method in order to determine wear and friction. Hardness and fatigue was characterised using nano-indentation and the coating adhesion was measured using scratch testing. Application of the coatings resulted in a significant reduction in wear. Wear factors as low as 3.65x10¯18m³/Nm were achieved for coated CoCr substrates compared to 3.53x10¯15m³/Nm reported in the literature for uncoated CoCr. The coating resulted in friction coefficients between 0.12 and 0.19 with hardness ranging from 6.65 and 15.63GPa. Similarly coating UHMWPE resulted in a reduction in the wear factor to less than 9.6x10¯17m³/Nm. It was concluded that the deposition of amorphous carbon coatings can improve wear of hip joint prostheses, although consideration must be made for the adhesion of the coating to the substrate so that it does not contribute to an early failure of the device. Improved adhesion can be achieved by reducing the hardness differential between the coating and adhesion, either through softening the coating or by using interlayers.
Advisors:
Wang, Chan; Pearce, Gillian
Publisher:
University of Wolverhampton
Issue Date:
2010
URI:
http://hdl.handle.net/2436/94223
Type:
Thesis or dissertation
Language:
en
Description:
A thesis submitted in partial fulfilment of the requirements of the University of Wolverhampton for the degree of Doctor of Philosophy
Sponsors:
EPSRC Case Studentship (Teer Coatings Ltd)
Appears in Collections:
E-Theses

Full metadata record

DC FieldValue Language
dc.contributor.advisorWang, Chanen
dc.contributor.advisorPearce, Gillianen
dc.contributor.authorKnox, Paulen
dc.date.accessioned2010-03-12T16:59:10Z-
dc.date.available2010-03-12T16:59:10Z-
dc.date.issued2010-
dc.identifier.urihttp://hdl.handle.net/2436/94223-
dc.descriptionA thesis submitted in partial fulfilment of the requirements of the University of Wolverhampton for the degree of Doctor of Philosophyen
dc.description.abstractIn this thesis Graphit-iC™, an amorphous carbon coating developed by Teer Coatings Ltd. was modified and deposited onto CoCr and WHMWPE substrates in order to improve the wear properties. It was identified that depositing a hard coating onto soft substrate would cause high stresses and lead to coating delamination. Consequently the polyethylene substrates were ion implanted with nitrogen to reduce the hardness differential at the substrate-coating boundary. The coating was characterised using a pin on disc method in order to determine wear and friction. Hardness and fatigue was characterised using nano-indentation and the coating adhesion was measured using scratch testing. Application of the coatings resulted in a significant reduction in wear. Wear factors as low as 3.65x10¯18m³/Nm were achieved for coated CoCr substrates compared to 3.53x10¯15m³/Nm reported in the literature for uncoated CoCr. The coating resulted in friction coefficients between 0.12 and 0.19 with hardness ranging from 6.65 and 15.63GPa. Similarly coating UHMWPE resulted in a reduction in the wear factor to less than 9.6x10¯17m³/Nm. It was concluded that the deposition of amorphous carbon coatings can improve wear of hip joint prostheses, although consideration must be made for the adhesion of the coating to the substrate so that it does not contribute to an early failure of the device. Improved adhesion can be achieved by reducing the hardness differential between the coating and adhesion, either through softening the coating or by using interlayers.en
dc.description.sponsorshipEPSRC Case Studentship (Teer Coatings Ltd)en
dc.language.isoenen
dc.publisherUniversity of Wolverhamptonen
dc.subjectHip jointen
dc.subjectProsthesisen
dc.subjectCoatingen
dc.subjectDLCen
dc.subjectGraphit-iCen
dc.subjectCoCen
dc.subjectUHMWPEen
dc.subjectWearen
dc.titleDevelopment of high performance tribological coatings for application onto hip joint prosthesesen
dc.typeThesis or dissertationen
dc.type.qualificationnamePhDen
dc.type.qualificationlevelDoctoralen
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