Long-term wetting and corrosion characteristics of hot water treated aluminum and copper fin stocks

Experimental studies were conducted to investigate the long-term wetting and corrosion characteristics of hot water treated aluminum and copper fin stocks. This was done by subjecting them to wet/dry cycling consisting of alternately dipping the fin samples into distilled water for 5 min followed by air drying with a fan for 25 min. To simulate the fins of a heat exchanger, fin stocks were formed in a wavy shape using hand operated fin dies and a typical lubricant oil. The fin samples, including the formed and the unformed aluminum and copper stocks, were treated using hot water by immersing them in either 82 or 100 °C water for 20 min. The wettability and corrosion evaluations consisted of periodic measurements of the advancing/receding contact angles and weights of the fin samples. SEM photos were taken to show the appearance of the sample surfaces. Further, X-ray photoelectron spectroscope examinations were performed to analyze the atomic composition at the sample surfaces. The test results suggest that the hot water soak is an effective means to improve the surface wettability of both aluminum and copper surfaces. The soaking procedure was capable of producing wettable fin that was durable to wet/dry cycling. The soaking operation and follow-on wet/dry cycling treatment did not cause significant material loss by general corrosion.