The negative influence of Fe2P pigments on the anticorrosion properties of zinc dust primers

 
Zinc primers are recognized as the most effective anti-corrosion paint systems to date, and are considered as nearly the only type of paints able to provide cathodic protection. For decades, zinc primers have been abundantly used in marine and protective applications such as off-shore, bridges, windmills and shipbuilding. During the last decades, the production of zinc dust for this application has gone through a lot of changes. Umicore Zinc Chemicals, a business unit of Umicore is a global supplier of zinc dust for this application and has four production facilities worldwide (China, Belgium, Malaysia and Norway). Umicore is a global producer of zinc dust, producing zinc dust both by atomization (Belgium) and distillation processes (Norway, Malaysia, China). Ferrophos® is a grey ferro-alloy pigment, consisting primarily of Fe2P with traces of FeP and SiO2. It is said to be electrically and thermally conductive as well as chemically inert under normal conditions. Its particles are comparable in size and distribution with paint grade zinc dust particles. Literature1-6 equally states that Ferrophos can replace 40 wt % of the zinc dust in a zinc dust primer, without reducing its corrosion resistance.