title: Crystallographic changes in calcium phosphates during plasma-spraying.
abstract: Coating hydroxyapatite (HA) onto metal implant surfaces using the plasma-spraying technique has been investigated in several laboratories as a means of improving the mechanical properties of the bulk ceramic. This study describes crystallographic changes which can occur during the plasma-spraying of calcium phosphate powders. A precipitated calcium-deficient apatite and a high temperature near-stoichiometric HA were each sprayed onto metal substrate in an argon plasma using several hydrogen gas flow conditions at various temperatures. The surfaces were examined by X-ray diffraction and scanning electron microscopy. The plasma-sprayed products were identified as a mixture of calcium phosphates including HA, beta-tricalcium phosphate (beta-TCP) and calcium oxide. Stoichiometric HA when plasma-sprayed showed the least (5%) degradation. Since beta-TCP is more resorbable than HA in vivo, varying the HA/beta-TCP ratio on the plasma-sprayed surface may provide a method to control surface dissolution of the coating.
authors.affiliation: Eastman Dental Center, Department of Oral Sciences, Rochester, NY 14620.
authors.forename: L G
authors.initials: LG
authors.lastname: Ellies
authors.forename: D G
authors.initials: DG
authors.lastname: Nelson
authors.forename: J D
authors.initials: JD
authors.lastname: Featherstone
mesh_terms: D001672:Biocompatible Materials; D001842:Bone and Bones; D002130:Calcium Phosphates; D017886:Durapatite; D006801:Humans; D006882:Hydroxyapatites; D008422:Materials Testing; D008670:Metals; D008855:Microscopy, Electron, Scanning; D019736:Prostheses and Implants; D013499:Surface Properties; D014961:X-Ray Diffraction
chemical_list: D001672:Biocompatible Materials; D002130:Calcium Phosphates; D006882:Hydroxyapatites; D008670:Metals; C485817:beta-tricalcium phosphate; D017886:Durapatite; C018392:tricalcium phosphate