Hydroxyapatite-coated Ti-6Al-4V part 2: the effects of post-deposition heat treatment at low temperatures.
The present investigation explores the effects of a 90-h post-deposition annealing treatment at 400 degrees C in air on the crystallographic and chemical properties of a plasma-sprayed hydroxyapatite (HA) coating, the thickness and composition of the interfacial oxide layer, and the fatigue behaviour of the underlying Ti-6Al-4V substrate. X-ray diffraction analysis revealed that significant recovery of the crystalline HA structure occurred as a result of the treatment, however, as compared with results obtained through treatment at higher temperatures, recovery obtained through use of the present treatment was incomplete. X-ray photoelectron spectroscopy analysis showed no changes in the constituents of the oxide layer, with the oxide species TiO2, Al2O3, V2O5, V2O3, and VO2 present on both the as-sprayed and the heat-treated substrates. A change in film thickness was observed, however, as evidenced by a change in colour from opaque bronze to dark purple. The fatigue resistance of the substrate was found to be significantly reduced by the heat treatment, with the lives of heat-treated coupons with coatings of all thicknesses closely resembling those of as-sprayed coupons with thick HA coatings and uncoated stress-relieved coupons presented in Part I of this study. Stress relief was identified as the most likely cause of these reductions.
Lynn
A K
AK
Department of Bioartificial Organs, Institute for Frontier Medical Sciences, Kyoto University, Japan.
DuQuesnay
D L
DL
D000497:Alloys / Q000494:pharmacology*; D000537:Aluminum Oxide / Q000378:metabolism; D001672:Biocompatible Materials / Q000737:chemistry*; D004305:Dose-Response Relationship, Drug; D017886:Durapatite / Q000737:chemistry*; D004577:Electron Probe Microanalysis; D006358:Hot Temperature; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D010100:Oxygen / Q000378:metabolism; D013314:Stress, Mechanical; D013696:Temperature; D013718:Tensile Strength; D013816:Thermodynamics; D013997:Time Factors; D014025:Titanium / Q000378:metabolism / Q000494:pharmacology*; D014961:X-Ray Diffraction
D000497:Alloys; D001672:Biocompatible Materials; C031462:titanium alloy (TiAl6V4); C009495:titanium dioxide; D017886:Durapatite; D014025:Titanium; D000537:Aluminum Oxide; D010100:Oxygen