title: Effect of Nitinol surface treatments on its physico-chemical properties.
abstract: The main purpose of this work is the study of different physicochemical treatments on Nitinol slabs and wires, with the aim of inducing the formation of a TiO(2) surface film capable of increasing the corrosion resistance of the material and of reducing the release of Ni when the Nitinol samples were immersed in simulated body fluid (SBF). To this end, a battery of measurements (surface roughness, contact angle, electrochemical corrosion, chemical analysis as a function of depth, and Ni release to SBF) has been used to characterize Nitinol commercial samples, as received, and also after the different treatments performed. The results clearly indicate the effectiveness of the passivation TiO(2) layer as a barrier against Ni leaching, and the detrimental effects of any processes (such as polishing or cutting) that result in exposure of areas not coated by the TiO(2) film. Chemical methods such as oxidation in nitric acid or hydrothermal treatment of the samples (by prolonged immersion in boiling water) seem to provide simple and efficient ways of forming TiO(2) films of adequate thickness on the Nitinol surface.
authors.affiliation: Aragon Nanoscience Institute (INA), University of Zaragoza, 50009 Zaragoza, Spain.
authors.forename: Luis Manuel
authors.initials: LM
authors.lastname: Pérez
authors.forename: Luis
authors.initials: L
authors.lastname: Gracia-Villa
authors.forename: José Antonio
authors.initials: JA
authors.lastname: Puértolas
authors.forename: Manuel
authors.initials: M
authors.lastname: Arruebo
authors.forename: Silvia
authors.initials: S
authors.lastname: Irusta
authors.forename: Jesús
authors.initials: J
authors.lastname: Santamaría
mesh_terms: D000497:Alloys / Q000737:chemistry / Q000378:metabolism; D001672:Biocompatible Materials / Q000737:chemistry; D001826:Body Fluids / Q000737:chemistry; D003343:Corrosion; D006801:Humans; D008422:Materials Testing; D009532:Nickel / Q000737:chemistry / Q000378:metabolism; D010084:Oxidation-Reduction; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry / Q000378:metabolism
chemical_list: D000497:Alloys; D001672:Biocompatible Materials; C013616:nitinol; D009532:Nickel; D014025:Titanium