Analysis of bleaching processes in aluminium pigmented chlorinated rubber coatings under osmotic effect

摘要

Aluminium pigmented chlorinated rubber coatings, widely used for steel ship protection, can be bleached when exposed to total immersion conditions. A deep study on the development of the decolouration processes of these coatings, applied on rolled steel specimens exposed to total immersion conditions in aqueous solutions with different salinity, has been carried out. The relationship between external salinity and contamination by sodium chloride of the steel/coating interface in the bleaching processes has been analysed. Besides, the influence of the osmotic processes in the coating bleaching has been established. Periodic visual inspections of the coating films, together with a deep analysis of the coating microstructure, by means of optical microscopy and scanning electron microscopy provided with microsonde analysis, were used. The bleaching processes of the coatings mainly depend on the salinity of the external solution, while the influence of the steel/coating interface contamination is not relevant.