title: [Corrosion resistance of casted titanium by compound treatments in the artificial saliva with different fluoride concentrations].
abstract: OBJECTIVE
  To study the corrosion resistance of casted titanium by plasma nitriding and TiN-coated compound treatments in the artificial saliva with different fluoride concentrations and to investigate whether compound treatments can increase the corrosion resistance of casted titanium.
  
  
  METHODS
  Potentiodynamic polarization technique was used to depict polarization curve and to measured the current density of corrosion (Icorr) and the electric potential of corrosion (Ecorr) of casted titanium (Group A) and casted titanium by compound treatments (Group B) in the artificial saliva with different fluoride concentrations. After electrochemical experiment, the microstructure was observed by scanning electron microscope (SEM).
  
  
  RESULTS
  The Icorrs of Group A and B in the artificial saliva of different fluoride concentrations were (1530.23 ± 340.12), (2290.36 ± 320.10), (4130.52 ± 230.17) nA and (2.62 ± 0.64), (7.37 ± 3.59), (10.76 ± 6.05) nA, respectively. The Ecorrs were (-0.93 ± 0.10), (-0.89 ± 0.21), (-0.57 ± 0.09) V and (-0.21 ± 0.04), (-0.17 ± 0.03), (-0.22 ± 0.03) V, respectively.The Icorrs of Group B were significantly lower (P < 0.01)than that of Group A. The Icorrs increased significantly with the increasing of fluoride concentrations (P < 0.01). The Ecorrs of Group B were significantly higher than that of Group A (P < 0.01). The SEM confirmed the microstructure in the casted titanium was much severely than that in Group B, the microstructure in Group A and B corroded more and more heavily with increasing of fluoride concentrations.
  
  
  CONCLUSIONS
  The increase of fluoride concentrations influence the corrosion resistance of both treated and untreated casted titanium negatively, but plasma nitriding and TiN-coated compound treatments can significantly increase the corrosion resistance of casted titanium.
authors.affiliation: Department of Prosthodontics, College of Stomatology, The Fourth Military Medical University, Xi'an 710032, China.
authors.forename: Xian-li
authors.initials: XL
authors.lastname: Wang
authors.forename: Tian-wen
authors.initials: TW
authors.lastname: Guo
mesh_terms: D003343:Corrosion; D005459:Fluorides / Q000737:chemistry*; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D017672:Nitrogen Compounds / Q000737:chemistry; D058626:Plasma Gases / Q000737:chemistry; D012464:Saliva, Artificial / Q000737:chemistry*; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*
chemical_list: D017672:Nitrogen Compounds; D058626:Plasma Gases; D012464:Saliva, Artificial; C041500:titanium nitride; D014025:Titanium; D005459:Fluorides