It has been known that contacts of dis-similar metals in an oral cavity cause galvanic pain, corrosion or discoloration of metals. These unfavorable phenomena have been considered in the dental field for a long time. As the electrochemical aspects,the corrosion is explained by an intersection of the polarization curves when two dis-similar metals have contacted each other.
The purpose of this study is to investigate the electrochemical behavior of dis-similar metal contacts by developing the analysis of polarization curves.
Polarization curves of constituent metals and the curve obtained from the relation between an electrode potential and current were measured.In this circuit,the value of current was altered with changing resistance.
Commercially pure gold, pure titanium,cobalt-chromium alloys, and nickel-titanium alloys were provided as the electrodes.
The electrolyte solution was 0.1 N NaCl.
The electrochemical reaction on the contact of dis-similar metals has been discussed on the experimental results obtained.
The results are as follows:
1. The polarization curve with a constant potentionstatic method corresponded to a potention-current curve which was obtained in the electric circuit constructed with two dis-similar metals and a resistance in a series. The same value of the short-circuit potention and current was obtained from different two curves described above.
2. As a tendency, the short-circuit current decreased quickly with time when a polarization potention strongly depended on a polarization current.
3. Since the polarity of the open-circuit potention did not change,it is explained that the same kind of redox reactions between dis-similar metals take place even after a long process time proceed.