| Summary: | This thesis documents studies directed towards the development of electrochemical measurement procedures capable of quantifying corrosion resistance and/or the corrosion rate in Tin Mill products, and in particular steel food/beverage cans. Chapters 3 and 4 describe electrochemical studies carried out using commercially produced cans. Conventional corrosion evaluation techniques were compared with Electrochemical Impedance Spectroscopy (EIS) data. EIS was found to provide useful information regarding container corrosion performance, however statistical variation from can to can required the use of large sample populations unless cans could be conserved between measurements. This was achieved by the development of "sealed-in-electrodes", which were used to identify trends in can coating performance. Sealed-in-electrodes form the basis of a predictive corrosion test method, whereby short-term electrochemical measurements may be extrapolated to predict long-term corrosion performance. Conventional electrochemical techniques provide a surface averaged measurement of the corrosion performance of coated metals, giving no information regarding the spatial distribution of penetrative defect sites in the organic coating. For this reason, a novel method for defect detection was developed, exploiting the phenomenon of electrogenerated chemiluminescence (ECL) in conjunction with digital (CCD) photography. The development, optimisation and evaluation of techniques for the spatially resolved characterisation of penetrative coating defect populations using luminol ECL is described in chapters 5 - 7. A proposed mechanism and kinetic model for the ECL process is described in chapter 5. Chapter 6 describes the application of luminol ECL to the detection of induced defects in a polymer laminate material, and an estimation of the limits of the technique. Chapter 7 describes the application of luminol ECL to the detection of defect populations in commercially produced polymer laminate cans. ECL images were suitable for computerised image analysis, providing information on the frequency, size distribution and location of penetrative defects.
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