Hard coatings generated by means of PVD or CVD processes have proven to protect tools successfully from wear. With a thickness of a few micrometers, these coats significantly increase the performance and useful life particularly of machining tools. Nowadays, they are also used successfully as a decorative wear protection e.g. on bathroom fittings, glasses frames and other articles of everyday use. Due to their great hardness, the nitrides, borides and carbides of the elements from the subgroups 4 to 6 are the most interesting coating systems (e. g. Ti, Cr, W, Zr).