MECHANISM OF ATMOSPHERIC CORROSION OF COPPER IN THE PRESENCE OF SUBMICRON AMMONIUM-SULFATE PARTICLES AT 300 AND 373 K

The corrosion mechanism of copper at 373 and 300 K in the presence of submicron (NH4)2SO4 particle deposits has been investigated. Several i n situ techniques have been used to monitor the corrosion process in r eal time. At and above the critical relative humidity of (NH4)2SO4, di ssolution of Cu is followed by formation of Cu2O, oxidation of Cu(I) i on to Cu(II) ions, and precipitation of antlerite [Cu3(SO4)(OH)4], bro nchantite [Cu4(SO4)(OH)6], or posnjakite [Cu4(SO4)(OH)6. H2O]. The amo unt of corrosion product formed increases with amount of (NH4)2SO4 par ticles, relative humidity (RH), and temperature. The in situ technique s allowed us to confirm and refine the individual steps in the multist ep mechanism proposed in earlier work.