Title page for ETD etd-07112011-163318


Document Type Master's Dissertation
Author Hohls, Adrian Christian
Email adrian.hohls@cmti.co.za
URN etd-07112011-163318
Document Title Investigation into phase transformation of Yttria stabilized zirconia femoral heads
Degree MEng
Department Mechanical and Aeronautical Engineering
Supervisor
Advisor Name Title
Prof N D L Burger Supervisor
Keywords
  • phase transformation
  • Y-TZP
  • Yttria stabilised tetragona zirconia
  • femoral heads
Date 2011-04-06
Availability unrestricted
Abstract
27 Retrieved Yttria Stabilised Tetragonal Zirconia (Y-TZP) femoral heads were studied for the occurrence of tetragonal to monoclinic phase transformation and the effects that such transformation has on the bearing surface. The mean monoclinic percentage found is 53.6% with 25 of the samples having transformed more than 20%. This finding nullifies earlier predictions that it would take 25 to 30 years to transform to a monoclinic content of 30 to 40% inside the human body (Chevalier, Drouin & Calés 1997). It was however shown that Hot Isostatic Pressed (HIP’ed) Y-TZP femoral heads have a better, though still not adequate, resistance to phase transformation in the human body than non-HIP’ed femoral heads.

Results of various investigations show that this transformation degrades the surface condition of the femoral heads, which in turn increases wear and subsequently decreases the survival rate of the prosthesis due to a greater risk of aseptic loosening.

It is postulated that a great contributing factor to the phase transformation is increased temperatures inside the bearing couple, due to inadequate lubrication between the two bearing surfaces.

Tetragonal to monoclinic phase transformation and its associated effects renders Y-TZP femoral heads less attractive for hip replacements.

© 2010, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria.

Please cite as follows:

Hohls, AC 2010, Investigation into phase transformation of Yttria stabilized zirconia femoral heads, MEng dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-07112011-163318/ >

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