Joshi, Adwait (2025) Development of hydroxyapatite and wollastonite coatings for orthopaedic implant biomedical applications. Master of Engineering thesis, Dublin City University.
The project aims to develop orthopaedic implants for biomedical applications. At present, millions of people suffer from hip issues; therefore, total hip replacement surgery has become more common; thus, finding a better hip implant is imperative. This study uses the titanium implant as a substrate due to its lightness, strength, durability, and biocompatibility despite its low bioactivity. Hydroxyapatite has a similar chemical composition to inorganic bone due to its bioactive nature. Biocoating fulfils both the function of bioactivity of Hydroxyapatite and the superior mechanical property of titanium. However, the major drawbacks of this Hydroxyapatite coated titanium implant are the poor mechanical properties of Hydroxyapatite and the bioinertness of the titanium. The present study intends to add Wollastonite as an additive to improve its mechanical and bioactive properties suitable for load-bearing applications.
Hydroxyapatite was initially spray-dried with the previous process parameters. Wollastonite was spray-dried with the same process parameters as Hydroxyapatite. As observed by scanning electron microscope, spray-dried Wollastonite showed acicular shape morphology, which affected its flowability. Therefore, Hydroxyapatite, Wollastonite, and Hydroxyapatite/Wollastonite composite powder were coated on the titanium substrate using a dip-immersion technique to address this issue. In the dip coating, the precursors of calcium, phosphate and silicate were used to dip coat Hydroxyapatite and Wollastonite on to a titanium substrate, respectively and Wollastonite powder in 10, 20 and 30 wt.%, respectively was added to Hydroxyapatite gel to form a Hydroxyapatite/Wollastonite composite coating. For spray coating, Hydroxyapatite, Wollastonite was spray coated onto a titanium substrate with parameters obtained from spray drying and Wollastonite was added in 20-50 wt.% to Hydroxyapatite slurry and spray coated onto a prepared titanium substrate. Overall, for dip-coated composite samples, the addition of 10 wt.% Wollastonite to composite coatings presented optimal results, whereas for spray-coated composite samples, 20 wt.% Wollastonite added to the composite coatings showed better coating cracks, porosity, microstructure results with better crystallinity. Therefore, new coating techniques requiring further research were produced as an outcome of the research.
Item Type: | Thesis (Master of Engineering) |
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Date of Award: | 7 January 2025 |
Refereed: | No |
Supervisor(s): | Stokes, Joseph and Benyounis, Khaled |
Subjects: | Engineering > Mechanical engineering |
DCU Faculties and Centres: | DCU Faculties and Schools > Faculty of Engineering and Computing > School of Mechanical and Manufacturing Engineering |
Use License: | This item is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 4.0 License. View License |
ID Code: | 30636 |
Deposited On: | 11 Mar 2025 09:30 by Joseph Stokes . Last Modified 11 Mar 2025 09:30 |
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