2010 Volume 59 Issue 10 Pages 360-365
A brief review is given, with selected examples, of a novel use of advanced scanning electron microscopy for corrosion studies. Examples included are (a) water-drop corrosion of iron, (b) corrosion of copper in NaCl solution, and (c) deformation of matrix around the tip of cracks developed in high-temperature resistant steels. Through the use of test specimens with “well-defined” or “nearly perfectly-defined” surfaces, prepared by mechanical polishing followed by final treatment by rf-GD sputtering, subtle surface evolutions associated with the initial stages of corrosion of iron and copper have been revealed at the clarity never seen before. Specifically for water-drop corrosion of high purity iron, where MnO and MnS inclusions of dimensions of up to several microns are present, often forming complex inclusions, it has been demonstrated for the first time that nano-cavities, which are precursors for pitting, are always formed not by dissolution of MnS− inclusions, as previously suggested for pitting of stainless steels, but by the dissolution of MnO inclusions.