title: [Corrosion resistance and wear resistance of Ni-Cr alloy after coating titanium nitride (TiN) in oral containing fluorine environment].
abstract: OBJECTIVE
  The aim of this study was to evaluate the corrosion resistance and wear resistance of Ni-Cr alloy after coating titanium nitride (TiN) in oral containing fluorine environment.
  
  
  METHODS
  Physical vapor deposition was established to coat titanium nitride (TiN) on the surface of dental cast Ni-Cr alloy to form TiN/Ni-Cr compound. Both Ni-Cr alloy and TiN/Ni-Cr compound were exposed to 37 degrees centigrade, artificial saliva containing 0.24% NaF. The polarization curves of the specimens were measured by PARSTAT 2273 electrochemical station to investigate its corrosion resistance. Vicker's hardness was measured by HXD-1000TMC/LCD micro-hardness tester to investigate its wear resistance. Statistical analysis was performed by SAS 8.2 software package for Student's t methods.
  
  
  RESULTS
  The corrosion potential of Ni-Cr alloy was -362.407 mV, the corrosion current density was 1.568μAcm(-2),the blunt-breaking potential was 426 mV bofor TiN coating. The corrosion potential of TiN/Ni-Cr compound was -268.638 mV, the corrosion current density was 0.114μAcm(-2),the blunt-breaking potential was 1142 mV after TiN coating. Polarization curves showed TiN/Ni-Cr compound improved the corrosion potential and blunt-breaking potential, decreased the corrosion current density. The Vicker's hardness of Ni-Cr alloy was 519.75±27.27 before TiN coating, the Vicker's hardness of TiN/Ni-Cr compound was 803.24±24.64, the D-value between them was 283.49±39.34. The difference of Vicker's harnesses between Ni-Cr alloy and TiN/Ni-Cr compound had significant (P<0.01).
  
  
  CONCLUSIONS
  The results demonstrate that the TiN coating can improve the corrosion resistant to F-and the surface hardness of Ni-Cr alloy. Supported by Research Fund of Science and Technology Commission of Shanghai Municipality (Grant No.08DZ2271100), Shanghai Leading Academic Discipline Project (Grant No.S30206 ) and Research Fund of Health Bureau of Shanghai Municipality (Grant No.2009074).
authors: Department of Prosthodontics,Ninth People's Hospital,College of Stomatology,Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology. Shanghai 200011, China. wengweimin31@126.com
authors: Wei-Min
authors: WM
authors: Weng
authors: Wei-Qiang
authors: WQ
authors: Yu
authors: Wei-Lan
authors: WL
authors: Shan
authors: Fu-Qiang
authors: FQ
authors: Zhang
mesh_terms: D003343:Corrosion; D003722:Dental Alloys; D004563:Electrochemistry; D005459:Fluorides; D005461:Fluorine; D012464:Saliva, Artificial; D013499:Surface Properties; D014025:Titanium
chemical_list: D003722:Dental Alloys; D012464:Saliva, Artificial; D005461:Fluorine; C041500:titanium nitride; D014025:Titanium; D005459:Fluorides