Novel nanocomposite coatings combine protection with colour effects

New colored protective coatings offer the same corrosion and wear protection as colorless coatings while their colouration opens new opportunities. Red could for instance be used as a warning color on surfaces which can get very hot. The new possibilities from combining protection and color in such coatings will be demonstrated by INM – Leibniz Institute for New Materials at this year’s Hannover Fair from 13 to 17 April as an exhibitor at the leading Research & Technology trade fair (stand B46 in hall 2). “Incorporating colored pigments in nanocomposites make coatings possible which are not only protective but also deliver additional visual information via their colouration,” explains Peter William de Oliveira, head of the IZI - Innovation Center INM. A protective coating for surfaces of ovens, chimneys or certain automotive parts could be colored red for instance. So such parts would not only be protected from corrosion, wear and oxidation but at the same time also be distinctive to the consumer by virtue of their color To create a full red shade without brown content, INM researchers are currently working on ceramic particles with red pigments free from iron oxide. Chemical compounds previously used were not very suitable for such applications. “Organic compounds do make for very nice reds – but they are unsuitable for such protective coatings, since organics do not survive high temperatures,” explains the physicist de Oliveira, “Iron oxides do withstand high temperatures when used as coloring particles for reds, but do not give full reds.” Black colored coatings with a thickness of two to five micrometers can withstand temperatures up to 900 degrees Celsius, but also coatings with a reddish brown color with resistance can endure up to 500 degrees Celsius. INM researchers are also developing protective coatings using blue and green pigments. Current developments at INM enable the use of these colored glass-ceramic layers on metals and glasses. The pigments are incorporated in sol-gel nanocomposites and applied by dipping or spraying.