Study of the effect of acetic acid vapor on copper corrosion at 40 and 80% relative humidity

Copper corrosion rate and corrosion products originating from acetic acid vapors have been studied using gravimetric, scanning electron microscopy, X-ray photoelectron spectroscopy, and argon-ion sputtering techniques. Copper specimens were exposed to the action of 10, 100, and 300 ppm acetic acid vapors generated in laboratory experiments at 40 and 80% relative humidity (RH) for a period of 21 days and at 30 deg C. The copper corrosion rate was in the range from 0.08 to 0.17 mg/dm exp 2 /day (mdd) for 40% RH and from 0.11 to 6.53 mdd for 80% RH. The main compounds found were cuprite [Cu sub 2 O], copper hydroxide [Cu(OH) sub 2 ], and copper acetate [Cu(CH sub 3 COO) sub 2 ]. A corrosion process model is proposed in which copper acetate is formed from copper hydroxide present on the copper surface.