Advancements in high performance zinc epoxy coatings

Lars Thorslund Pedersen, Claus Weinell, Hempel A/S, Denmark
Pascal Verbiest, Jeroen Van Den Bosch, Umicore Zinc Chemicals, Belgium

The present work investigates the use of alloyed zinc powders in zinc epoxy and zinc silicate coatings. It is found that small amounts bismuth has a dramatic effect on rust creep resistance while nickel and magnesium was not found to have any effect in the tested range. 0.5% bismuth in the zinc reduces rust creep by up to 80% after cyclic exposure according to ISO20340. With the alloyed zinc it is possible to formulate zinc epoxy coatings with rust creep below 1 mm in the test, thus achieving performance similar to what is know from zinc silicates.