title: Stress influence on interface in plasma-sprayed hydroxyapatite coatings on titanium alloy.
abstract: During clinical use of hydroxyapatite-coated implants, mechanical stresses are added to pre-existing residual stresses. The magnitude of these stresses affects the coating's performance. In this work we studied, by neutron diffraction and conventional X-ray diffraction methods, the macrostresses induced by a plasma-spraying process in the coating and at the interface. Neutron diffraction is one of the most suitable techniques for studying the strain distribution in a bulk material. X-ray diffraction was used to determine residual stress in the hydroxyapatite coating. Using a neutron diffraction method at the nearest point to the interface, we saw no real difference between the stress observed on coated and that on non-coated samples. With the X-ray diffraction method, it appeared that the stress level was compressive on every sample. The major advantage of the neutron diffraction method is that measurements can be made on a thick coating in a nondestructive way. The disadvantage is the large-gauge volume that we had to use because of the relatively low intensity of the neutron beam. Polishing is necessary for measurements inside the material when using the X-ray method. This destructive method may alter the stress field of the deposit.
authors.affiliation: UFR Odontologie, 2 rue du general Koenig, LACM, EA3304, Université de Reims-Champagne-Ardenne, F51100 France. pierre.millet@univ-reims.fr
authors.forename: P
authors.initials: P
authors.lastname: Millet
authors.forename: E
authors.initials: E
authors.lastname: Girardin
authors.forename: C
authors.initials: C
authors.lastname: Braham
authors.forename: A
authors.initials: A
authors.lastname: Lodini
mesh_terms: D017886:Durapatite / Q000737:chemistry*; D008433:Mathematics; D013314:Stress, Mechanical; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D017886:Durapatite; D014025:Titanium