Surface Observation and Depth Profiling Analysis Studies of Corrosion Products on Copper Exposed Outdoors

We characterized corrosion products formed on copper plates exposed to different outdoor conditions in urban, rural/coastal, and hot spring areas by means of field emission scanning electron microscopy (FE-SEM) and Auger electron spectroscopy (AES). FE-SEM observation revealed that the surface morphology was different for each exposure site. The surface morphology on copper exposed in the urban area was relatively uniform. By contrast, we observed three and two regions, respectively, with different types of surface morphology for copper exposed in the rural/coastal and hot spring areas. We attributed the plate-like corrosion products found on copper exposed in the urban and rural/coastal areas to posnjakite, We also observed spherical corrosion products and assigned them to cuprite, However, we attributed the spherical corrosion products formed on copper exposed in the hot spring area to both cuprite, and copper sulfide, The depth profiles provided by AES in the different exposure areas revealed differences in concentration and elemental distribution.