ELECTROLYTE FOR PRODUCING THIN BLACK CONVERSION LAYERS ON LIGHT METALS

摘要

The invention relates to an ammonia-, cyanide- and fluoride-free, and consequently environmentally acceptable electrolyte which is low in pollutants and which makes it possible to produce optically black layers on light metals or their alloys with a layer thickness of < 10  mu m and with almost identical optical absorptivity and thermal emissivity by means of ANOF processes. Compared with the hitherto known conversion layers obtained by the ANOF process, these layers have a substantially lower roughness number and consequently a lower particle generation. The use of the electrolyte in the ANOF process consequently provides a version of the coating method, in particular, for constructional parts or assemblies of complicated shape whose dimensional accuracy is subject to high requirements.