Corrosion properties of soldered joints. Part I: Electrochemical action of dental solder and dental nickel-chromium alloy

The corrosion properties of contact between six Ni-Cr alloys and two dental solders were evaluated. Ni-Cr alloys with low Cr content coupled with silver solder induced continuous galvanic current, whereas Ni-Cr alloys with high Cr and some Mo content coupled with silver or gold solder induced galvanic current for a short time. Six Ni-Cr alloys were divided into two groups according to the dissolution of Ni, one low-resistance and the other high-resistance. The initial equilibrium was induced between high-resistance Ni-Cr alloys and both solders by less current density, which implies a smaller degree of corrosive current than that in low-resistance alloys. Corrosion was observed in the silver solder coupled with high-resistance Ni-Cr alloy, but was not found in the gold solder coupled with both alloys. In soldering Ni-Cr alloy it is better to use a gold solder and a high-resistance Ni-Cr alloy for corrosion resistance.