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Effect of steam treatment during plasma spraying on the microstructure of hydroxyapatite splats and coatings.

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Effect of steam treatment during plasma spraying on the microstructure of hydroxyapatite splats and coatings.

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dc.contributor.author Li, H.
dc.contributor.author Khor, Khiam Aik.
dc.contributor.author Cheang, P.
dc.date.accessioned 2012-08-27T08:44:20Z
dc.date.available 2012-08-27T08:44:20Z
dc.date.copyright 2006
dc.date.issued 2012-08-27
dc.identifier.citation Li, H., Khor, K. A., & Cheang, P. (2006). Effect of steam treatment during plasma spraying on the microstructure of hydroxyapatite splats and coatings. Journal of Thermal Spray Technology, 15(4), 610-616.
dc.identifier.issn 1059-9630
dc.identifier.uri http://hdl.handle.net/10220/8424
dc.description.abstract The major problems with plasma sprayed hydroxyapatite (HA) coatings for hard tissue replacement are severe HA decomposition and insufficient mechanical properties of the coatings. Loss of crystalline HA after the high-temperature spraying is due mainly to the loss of OH− in terms of water. The current study used steam to treat HA droplets and coatings during both in-flight and flattening stages during plasma spraying. The microstructure of the HA coatings and splats was characterized using scanning electron microscope, Raman spectroscopy, Fourier transform IR spectroscopy, and x-ray diffraction. Results showed that a significant increase in crystallinity of the HA coating was achieved through the steam treatment (e.g., from 58 to 79%). In addition, the effects were dependent on particle sizes of the HA feedstock, more increase in crystallinity of the coatings made from smaller powders was revealed. The Raman spectroscopy analyses on the individual splats and coatings indicate that the mechanism involves entrapping of water molecules by the individual HA droplets upon their impingement. It further suggests that the HA decomposition has already taken place before the impingement of the droplets on precoating or substrate. The improvement in crystallinity and phases, for example, from tricalcium phosphate and amorphous calcium phosphate to HA, was achieved by reversing the HA decomposition through providing extra OH−. Furthermore, the steam treatment during the spraying also accounts for remarkably increased adhesion strength from 9.09 to 23.13 MPa. The in vitro testing through immersing the HA coatings in simulated body fluid gives further evidence that the economic and simple steam treatment is promising in improving HA coating structure.
dc.language.iso en
dc.relation.ispartofseries Journal of thermal spray technology
dc.rights © 2006 ASM International. This paper was published in Journal of Thermal Spray Technology and is made available as an electronic reprint (preprint) with permission of ASM International. The paper can be found at the following official URL: [http://dx.doi.org/10.1361/105996306X146938].  One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law.
dc.subject DRNTU::Engineering::Mechanical engineering.
dc.title Effect of steam treatment during plasma spraying on the microstructure of hydroxyapatite splats and coatings.
dc.type Journal Article
dc.contributor.school School of Mechanical and Aerospace Engineering
dc.identifier.doi http://dx.doi.org/10.1361/105996306X146938
dc.description.version Published version

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