2023 年 62 巻 1 号 p. 119-123
We have been examined the suppression of pitting corrosion in copper tube used for heat transfer in cooling water systems with absorption chillers. The corrosion was caused by the relationship between the carbon film on the copper tube surface and the water quality flowing through the tube. Phosphonic acid, and benzotriazole (BTA) were used as water treatment chemical due to suppress pitting corrosion. We reported silicate ion and calcium ion are effective for the corrosion resistance of copper in the presence of phosphonic acid, and also studied the effect of pH and carbon film. In this study, BTA was added to the system containing these three factors, and the effect of BTA on the corrosion resistance of copper tubes was investigated using electrochemical measurements. As the concentration of BTA increased, the current density was suppressed and the BDP became larger. No significant difference was observed with pH, but there was a difference with and without carbon film. From these results, it was considered that corrosion inhibition is more effective with increasing BTA concentration.
