Quantification of corrosion phenomena in plastic processing machines

In a model platelet system the corrosion of metallic materials was studied by processing polyethylene, polyphenylene sulfide, and glass-fibre-reinforc ed polyphenylene sulfide. The measurement methods used were scanning electr on microscopy (images), electron-probe microanalysis (lateral element maps) , secondary-ion mass spectrometry (depth profiles), X-ray photoelectron spe ctroscopy (chemical bonding), and grazing-incidence X-ray diffraction (stru ctures of crystalline compounds). As nondestructive measure of corrosive at tack, grazing-incidence X-ray diffraction, using the intensity ratio (IFe-O /I-Fe), was found to be the method of choice. The reproducibility for the t otal procedure was found to range between 6 and 13% (rel.). The intensity r atio was examined as function of depth, of the time of stress, of material composition, and of the surrounding atmosphere. Oxides were identified as m ain corrosion products. The extent of oxide formation is proportional to th e time elapsed after processing.