A recent technique developed in hip arthroplasty is hip resurfacing (HR) which is a much smaller and less invasive implant system as compared to the commonly used total hip replacement (THR) and therefore more attractive. In the current design, both implant parts used in HR are made of CoCrMo alloy which provide sufficient mechanical strength to the implant under load-bearing situations. Metal on metal implants have however been reported to cause metal ion release and wear debris in these coupling bearings. Ceramics would offer a much better solution in terms of wear resistance, but are too brittle for use in HR where excellent mechanical and tribological properties are a prerequisite. This project aimed at the development of ceramic/metal graded interpenetrating phase composites (GIPCs) for possible application in HR implants in order to reduce metal wear debris and ion release while providing the necessary mechanical properties. Graded porosity ceramics with continuously aligned open pores were successfully fabricated using a double-side cooling freeze casting setup and subsequently infiltrated with metal to produce ceramic/metal GIPCs. The effects of slurry solid content, temperature, cooling rate and the introduction of electrophoretic deposition (EPD) on the microstructure of freeze cast ceramic preforms were investigated. The addition of EPD before freeze casting altered the microstructure substantially with decreasing lamellar spacing and reduced porosity gradient. Processing conditions of ceramic preforms that were suitable for the fabrication of GIPCs were identified. Vacuum and centrifugal casting techniques were investigated and compared for the metal infiltration. The centrifugal casting turned out to be a more efficient method. The fabricated GIPCs possessed high compression strength, good wear resistance and could potentially be used as a candidate for the HR implants. Finally, the fabrication of a prototype in acetabular shape was demonstrated with a hemisphere shaped mould using the freeze casting and metal infiltration techniques.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:556731 |
| Date | January 2011 |
| Creators | Preiss, Annemarie |
| Publisher | University of Bristol |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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