Abstract
Electrochemical measurements of SUS316L and BNi‐5 were carried out to investigate the corrosion resistance of the portion brazed with nickel brazing filler metals in the heat exchanger made of austenitic stainless steel. Corrosion potentials and galvanic currents of SUS316L and BNi‐5 were measured in 0.06 mol/L sodium chloride and sodium sulfate solution at room temperature and at 80℃. The corrosion potential of BNi‐5 in NaCl solution at 80℃ is lower than that in NaCl solution at room temperature, while the corrosion potential of SUS316L in NaCl solution at 80℃ is almost the same as that in NaCl solution at room temperature. The corrosion potential of SUS316L was nobler than that of BNi‐5 in NaCl solution. The potential difference between SUS316L and BNi‐5 in NaCl solution at 80℃ was up to about 0.4V. The galvanic current between SUS316L and BNi‐5 in NaCl solution at room temperature was almost 0 μA/cm2, while the galvanic current at 80℃ was up to about 0.2μA/cm2. We found that the galvanic corrosion on couple between BNi‐5 and SUS316L may be induced in the solution containing chloride ion at high temperature.
