| Popis: |
Zinc based coatings are effective of protecting steel structures for various industrial applications due to their cathodic protection properties on top of the barrier protection. Hot dip galvanization was the most historical technique under this category. Despite of their historical background, using hot dip galvanization in some current applications has become questionable specially due to their inability to apply on site which reduces the productivity and adverse environmental consequences galvanization process may can cause. Zinc rich coatings trying to replace hot dip galvanization in these demanding applications though they have another set of industrial challenges to satisfy. One such a demand is to cater aesthetic requirements, to provide coloured coating without compromising corrosion protection properties. Current practice is to apply a multi coat system which may contain three or more layers. Thus, based on the critical service related problems of current zinc based coatings, this work is focused to develop processes to provide an effective and reliable zinc based corrosion protective coating system which satisfy aesthetic requirements, aiming building and construction related applications. To enhance the productivity compared to the current coating systems, it is expected to develop a single layer coloured zinc rich coating accommodating different corrosion protection strategies. Colouring pigment with suitable size distribution and chemical properties are studied for this development to fulfil the aesthetic purpose, while examining the effect of other additives to enhance the corrosion protection properties. Synergistic effect of different corrosion protection strategies is evaluated to review the suitability of the single colour zinc coating. Overall corrosion protection performance of the developed coatings is evaluated by methodologies based on scientific principles and international standards to get quantitative and qualitative details of coatings properties. Details of this development with evaluation results will be presented. Alternative solutions to cater industrial demands will also be discussed. |
