An Electrochemical Study On Corrosion Behaviors Of Ni-Cr Alloy, Ni-Cr Alloy With Electroplated Au Film And Au Alloy In Artificial Saliva

Background Dental alloys are widely used in clinical prosthodontic treament. Studies reveal that precious alloys such as Au, Pd, Pt, et al. have perfect corrosion resistance. However, the rareness and high price limit the wide useness of precious alloys. Many kinds of prostheses are usually made by non-precious metals such as Ni-Cr alloys so far.It is a very complex electrolyte in oral environment. Non-precious alloys hav good corrosion resistance in a certain extent. But they would still corrode in oral environment unavoidably. The released mental ions are easy to cause some harmful effects on body. So it is significant to be treated by surface coating for them in some degrees.Au have exerllent biocompatibility and corrosion resistance. The technology of electrodeposite Au is very ripe now. A compact and firm Au film is coated on inner surface of porcelain-fused-to-metal (n.on-precious.metal) crown by this method. Therefore the problem of " marginal black line" can be solved perfectly. There is few report about electrochemical corrosion behaviors of dental alloys after electroplated, however.It is sensitive, accurate and quick to study the corrosion behaviors of metals by electrochemical method. The corrosion resistance of alloys can be mirrored directly by potentiodynamic polarization curves.Objective The aim of this study is to compare the corrosion behavior of Ni-Cr alloy, Ni-Cr alloy with electroplated Au film and Au alloy in artificial saliva.Methods The electrochemical corrosion behavior of Ni-Cr alloy, Ni-Cr alloy with electroplated Au film and Au alloy were evaluated by potentiodynamic polarization curves in artificial saliva at 37±1 °C (pH=6.8,5.6 respectively)to determine the corrosion potential(Ecorr) and self-corrosion current density(ICOrr)- Surface microstructures were observed by Field Emission Scanning Electron Microscope(FSEM).Results Results indicated that E_corr of Ni-Cr alloy was the most negtive , I_corr was the largest whether in neutral or in acid solution. The values of Au alloy turned out contrary to that of Ni-Cr alloy. The E_corr of Ni-Cr alloy with electroplated Au film was more positive than that of Ni-Cr alloy. The I_corr decreased after gold-plated . The scanning results of FSEM showed that Ni-Cr alloy appeared crystal lattice corrosion in artificial saliva .The corrosion of Au was not significant and Ni-Cr alloy with Au film was in the middle .Conclusion The corrosion resistance of Ni-Cr alloy with electroplated Au film improved significantly, but inferior to that of Au alloy. In acid medium, the corrosion resistances decreased in certain degrees.