Effect of Temperature on Corrosion behavior of Copper Silver Phosphorus Brazing Alloys in Chloride Containing Solution

Abstract

Abstract The groups of phosphorus-containing brazing alloys are the most favored filler metals used for joining copper and copper-base alloys. These brazing alloys are expected to have the optimum corrosion resistance during the application. However, failures arise at the braze joint generally caused and initiated by the corrosion of the brazing alloys when used at higher temperature than the room temperature. Since most studies of the phosphorus containing brazing alloys were performed at room temperature, this work has been extended to investigate the effect of various temperature on the corrosion behavior. Electrochemical measurements were carried out to observed the temperature effect with the temperature variation of 25, 40, 55 and 70 °C in 3.5% NaCl electrolyte. As the results, the copper-silver-phosphorus brazing alloy was undergone a selective dissolution by the attack of Cl-to the copper element. The temperature dependence of the alloy showed in agreement with the relationship of 2.3RT/F that have similar manner on pure copper tafel region. The schematic diagrams of the corrosion process were then proposed. This work could be helpful to understand in the field practically because the application temperature is usually higher than that of room temperature in general.