title: Effect of dissolution/precipitation on the residual stress redistribution of plasma-sprayed hydroxyapatite coating on titanium substrate in simulated body fluid (SBF).
abstract: The residual stress distributions in hydroxyapatite (HAp) coating with and without mixed hydroxyapatite/titanium (HAp/Ti) bond coating on commercially pure Titanium substrate (cp-Ti) were evaluated by Raman piezo-spectroscopy analysis. The Raman shifted position 962cm(-1), which is the symmetrical stretching of surrounded oxygen atoms with phosphorous atom ( [Formula: see text] ), was referred to analyses of stress dependency. The piezo-spectroscopic coefficient, which is a Raman shift value per stress (cm(-1)/GPa), was fitted from the result of four-points bending test of rectangular HAp bar and as-sprayed HAp on Zn plate. The calculated values were 3.89cm(-1)/GPa for the former and 7.11cm(-1)/GPa for the latter. By using these calibrations, the compressive residual stress in HAp coating with HAp/Ti bond coating (HA-B) has been found to be distributed in the range of -137MPa to -75MPa. For the heat-treated HAp coating (HA-B-HT) specimen, the compressive residual stresses placed in the range of -40--22MPa. The changes in the values of residual stress of the HAp coating after immersion in SBF were also evaluated. The residual stress in HA-WB specimens tend to change from compressive to tensile after 30 days immersion. The HA-B-HT specimens exhibited similar behavior and reached to zero stress after the immersion. The mechanism of the changes in residual stress would be the effect of stress redistribution around melted calcium phosphate particles to remained HAp splats.
authors.affiliation: Department of Materials Science, Maejo University, Chiangmai 50290, Thailand; Department of System Safety, Nagaoka University of Technology, Niigata 940-2188, Japan.
authors.forename: Achariya
authors.initials: A
authors.lastname: Rakngarm Nimkerdphol
authors.affiliation: Department of System Safety, Nagaoka University of Technology, Niigata 940-2188, Japan. Electronic address: otsuka@vos.nagaokaut.ac.jp.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Otsuka
authors.affiliation: Department of System Safety, Nagaoka University of Technology, Niigata 940-2188, Japan.
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Mutoh
mesh_terms: D000268:Adhesiveness; D040761:Biomimetic Materials / Q000737:chemistry; D001826:Body Fluids / Q000737:chemistry*; D018786:Bone Substitutes / Q000737:chemistry*; D011232:Chemical Precipitation; D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D065546:Drug Liberation; D017886:Durapatite / Q000737:chemistry*; D008422:Materials Testing; D058626:Plasma Gases / Q000737:chemistry*; D019736:Prostheses and Implants; D013314:Stress, Mechanical; D013500:Surface Tension; D014025:Titanium / Q000737:chemistry*
chemical_list: D018786:Bone Substitutes; D020099:Coated Materials, Biocompatible; D058626:Plasma Gases; D017886:Durapatite; D014025:Titanium
keywords: Calcium phosphate; Hydroxyapatite; Plasma-spray coating; Raman spectroscopy; Residual stress; Simulated body Fluid