title: Influence of noble metals alloying additions on the corrosion behaviour of titanium in a fluoride-containing environment.
abstract: Titanium alloys exhibit excellent corrosion resistance in most aqueous media due to the formation of a stable oxide film, and some of these alloys (particularly Ti-6Al-7Nb) have been chosen for surgical and odontological implants for their resistance and biocompatibility. Treatment with fluorides (F(-)) is known to be the main method for preventing plaque formation and dental caries. Toothpastes, mouthwashes, and prophylactic gels can contain from 200 to 20,000 ppm F(-) and can affect the corrosion behaviour of titanium alloy devices present in the oral cavity. In this work, the electrochemical corrosion behaviour of Ti-1M alloys (M = Ag, Au, Pd, Pt) was assessed in artificial saliva of pH = 3.0 containing 910 ppm F(-) (0.05 M NaF) through open circuit potential, E(OC), and electrochemical impedance spectroscopy (EIS) measurements. The corrosion behaviour of the Ti-6Al-7Nb commercial alloy was also evaluated for comparison. E (OC) measurements show an active behaviour for all the titanium alloys in fluoridated acidified saliva due to the presence of significant concentrations of HF and HF(2) (-) species that dissolve the spontaneous air-formed oxide film giving rise to surface activation. However, an increase in stability of the passive oxide layer and consequently a decrease in surface activation is observed for the Ti-1M alloys. This behaviour is confirmed by EIS measurements. In fact, the Ti-6Al-7Nb alloy exhibits lower impedance values as compared with Ti-1M alloys, the highest values being measured for the Ti-1Au alloy. The experimental results show that the corrosion resistance of the studied Ti-1M alloys is similar to or better than that of Ti-6Al-7Nb alloy currently used as biomaterial, suggesting their potential for dental applications.
authors.affiliation: Dipartimento di Scienza dei Materiali e Ingegneria Chimica (DICHI), Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Turin, Italy. francesco.rosalbino@polito.it
authors.forename: F
authors.initials: F
authors.lastname: Rosalbino
authors.forename: S
authors.initials: S
authors.lastname: Delsante
authors.forename: G
authors.initials: G
authors.lastname: Borzone
authors.forename: G
authors.initials: G
authors.lastname: Scavino
mesh_terms: D000497:Alloys / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D002327:Cariostatic Agents / Q000494:pharmacology; D020099:Coated Materials, Biocompatible / Q000737:chemistry / Q000494:pharmacology; D056831:Coordination Complexes / Q000138:chemical synthesis / Q000737:chemistry*; D003343:Corrosion; D017097:Electric Impedance; D004777:Environment; D005457:Fluoridation; D005459:Fluorides / Q000737:chemistry / Q000494:pharmacology*; D006046:Gold / Q000737:chemistry / Q000494:pharmacology; D008422:Materials Testing; D010165:Palladium / Q000737:chemistry / Q000494:pharmacology; D010984:Platinum / Q000737:chemistry / Q000494:pharmacology; D012834:Silver / Q000737:chemistry / Q000494:pharmacology; D014025:Titanium / Q000737:chemistry*
chemical_list: D000497:Alloys; D002327:Cariostatic Agents; D020099:Coated Materials, Biocompatible; D056831:Coordination Complexes; C070282:Ti-6Al-7Nb alloy; D012834:Silver; D010984:Platinum; D010165:Palladium; D006046:Gold; D014025:Titanium; D005459:Fluorides