Particle Characterisation and Depletion of Li 2 CO 3 Inhibitor in a Polyurethane Coating

摘要

The distribution and chemical composition of inorganic components of a corrosion-inhibiting primer based on polyurethane is determined using a range of characterisation techniques. The primer consists of a Li 2 CO 3 inhibitor phase, along with other inorganic phases including TiO 2 , BaSO 4 and Mg-(hydr)oxide. The characterisation techniques included particle induced X-ray and γ-ray emission spectroscopies (PIXE and PIGE, respectively) on a nuclear microprobe, as well as SEM/EDS hyperspectral mapping. Of the techniques used, only PIGE was able to directly map the Li distribution, although the distribution of Li 2 CO 3 particles could be inferred from SEM through using backscatter contrast and EDS. Characterisation was also performed on a primer coating that had undergone leaching in a neutral salt spray test for 500 h. Overall, it was found that Li 2 CO 3 leaching resulted in a uniform depletion zone near the surface, but also much deeper local depletion, which is thought to be due to the dissolution of clusters of Li 2 CO 3 particles that were connected to the external surface/electrolyte interface.