title: The effect of heat treatment on the morphology of D-Gun sprayed hydroxyapatite coatings.
abstract: In this study, the morphology of the Hydroxyapatite (HA) coatings sprayed on Ti alloy samples by Detonation Gun Spray (D-Gun) and the effect of aging before and after heat treatment in physiological solution were observed. Cross-sectional porosity and percentages of amorphous and crystal phase were measured using optical, electron microscopy, and X-ray diffraction analysis. Differential Thermogravimetric Analysis (DTA) was performed to estimate the glass-crystalline phase transformation temperatures. Heat-treatment at 300, 500, 700, 800 and 1200 degrees C were carried out to confirm DTA results. As a final analysis, the aging effect using Ringer's solution for 1 week on heat-treated and non-heat-treated samples was measured. It was observed that, in D-Gun sprayed samples, the cross-sectional porosity stayed in the accepted 5% range as reported for other spraying techniques.(1-5) On the other hand, surface porosity measured using the water immersion method remained in the conventional porosity limit of 15% for non-heat-treated samples. Heat-treatment had a small influence on the porosity while the crystallinity increased considerably; in addition, aging had little effect on HA crystallinity for heat treated samples. This work showed that D-gun sprayed HA coatings had lower porosity and better integrity than other coatings, due to which we can expect better performance during in vivo applications.
authors.affiliation: Lawrence Berkeley National Lab, Materials Science Division, 1 Cyclotron Road, MS 620-203, Berkeley, California 94720, USA. eerkmen@istanbl.edu.tr
authors.forename: Z E
authors.initials: ZE
authors.lastname: Erkmen
mesh_terms: D000497:Alloys; D020099:Coated Materials, Biocompatible; D006358:Hot Temperature; D006882:Hydroxyapatites; D007091:Image Processing, Computer-Assisted; D007552:Isotonic Solutions; D008855:Microscopy, Electron, Scanning; D016062:Porosity; D000077331:Ringer's Solution; D012995:Solubility; D013499:Surface Properties; D014025:Titanium
chemical_list: D000497:Alloys; D020099:Coated Materials, Biocompatible; D006882:Hydroxyapatites; D007552:Isotonic Solutions; C031462:titanium alloy (TiAl6V4); D000077331:Ringer's Solution; D014025:Titanium