Rutherford back-scattering and X-ray fluorescence for the study of corroded surfaces

Full text: A combination of Rutherford back-scattering (RBS) and X-ray fluorescence (XRF) has been used to examine some corroded surfaces and to find out the possible causes of corrosion. An example is given of tooth paste tubes where the inside surfaces were corroding and causing significant loss of the product. The grayish-brown, thin corrosion layer on the inside of the tooth paste tube was easily distinguishable from brand new, as well as from non-corroded used tubes, which are made from 99.7 % pure aluminum. The unused clean Al-tube shows some copper traces (about 0.3 μgram/cm2) on the surface, which almost disappears from the surface of the non-corroded used tube but reappears, to a lesser extent, on the surface of the corroded tube. The corroded layer has been found to consist mainly of P and Ca (about 1 μgram/cm2) with smaller quantities of Na, Mg, Si, S and Cl. The advantages of combining different nuclear analytical methods for studying surfaces of materials are highlighted. (author)