Chromating is a chemical, electroless surface treatment which generates inorganic layers consisting of oxide hydrates of aluminium and chrom. These layers are also called conversion layers. Extremely thin, even layers can be produced with this treatment.
They are used in the construction of components mainly where corrosion restistance is needed, but at the same time a conductive layer is indispensable (e.g. because of electromagnetic compatibility) and therefore anodised layers cannot be used.