CORROSION AND PROTECTION AT THE N.P.L.: 6: Electron microscopy and microprobe analysis Available to Purchase

Introduction The electron microscope and electron microprobe analyser are two of the newest and most advanced instruments available for corrosion and oxidation research. Metallographic techniques with a light microscope are very limited for the typically rough surfaces of corroded metal, and even a simple brown rust spot (Fig. 1a) takes on a new character when viewed with a scanning electron microscope (SEM), Fig. 1b. The depth of focus is at least three hundred times better than the light microscope, which makes the SEM very suitable for examining the surface topography of worn surfaces, fatigue fractures, hydrogen embrittled specimens, stress corroded materials or high temperature oxidation products. Normally, as the materials are conducting, the only preparation needed is to stick the piece of corroded metal on to a stub with conducting paint. Where specimens are too large to put into the microscope's vacuum system, a positive replica of the surface may be used instead.