title: Evaluation of mechanical properties and biological response of an alumina-forming Ni-free ferritic alloy.
abstract: PM 2000 is a Ni-free oxide dispersion strengthened Fe-20Cr-5Al alloy able to develop a fine, dense and tightly adherent alpha-alumina scale during high-temperature oxidation. Despite the high temperature involved during thermal oxidation (1100 degrees C), microstructural changes in the candidate material, a hot rolled product, hardly occurs. Consequently, the good mechanical properties of the as-received material are not significantly affected. Moreover, due to the high compressive residual stresses at the alumina scale, an increase in the fatigue limit from 500 to 530 MPa is observed. Such stresses also account for the high capability of the coating/metal system to withstand more than 1% tensile deformation without cracking. The biocompatibility of the alloy was assessed in comparison to commercial alumina. Saos-2 osteoblast-like cells were either challenged with PM 2000 particles, or seeded onto PM 2000 (with and without scale) solid samples. Viability, growth, and ALP release from cells were assessed after 3 or 7 days, while mineralization was checked at 18 days. This study has demonstrated that PM 2000 with and without scale are capable of supporting in vitro growth and function of osteoblast-like cells over a period of 18 days. Results from this study suggest that the resulting alumina/alloy system combines the good mechanical properties of the alloy with the superior biocompatibility of the alpha-alumina, for which there is very good clinical experience.
authors.affiliation: Physical Metallurgy Department, Centro Nacional de Investigaciones Metalúrgicas, CENIM-CSIC, Avda Gregorio del Amo 8, 28040 Madrid, Spain. jlg@cenim.csic.es
authors.forename: J L
authors.initials: JL
authors.lastname: González-Carrasco
authors.forename: G
authors.initials: G
authors.lastname: Ciapetti
authors.forename: M A
authors.initials: MA
authors.lastname: Montealegre
authors.forename: S
authors.initials: S
authors.lastname: Pagani
authors.forename: J
authors.initials: J
authors.lastname: Chao
authors.forename: N
authors.initials: N
authors.lastname: Baldini
mesh_terms: D000537:Aluminum Oxide / Q000032:analysis / Q000737:chemistry*; D001672:Biocompatible Materials / Q000737:chemistry*; D002448:Cell Adhesion; D018929:Cell Culture Techniques / Q000379:methods*; D002454:Cell Differentiation; D049109:Cell Proliferation; D002470:Cell Survival; D002478:Cells, Cultured; D004548:Elasticity; D005290:Ferric Compounds / Q000032:analysis / Q000737:chemistry*; D006244:Hardness; D006801:Humans; D008422:Materials Testing; D009532:Nickel; D010006:Osteoblasts / Q000166:cytology* / Q000502:physiology*; D019736:Prostheses and Implants; D013499:Surface Properties; D013718:Tensile Strength
chemical_list: D001672:Biocompatible Materials; D005290:Ferric Compounds; C501845:PM 2000; D009532:Nickel; D000537:Aluminum Oxide