minimum period of a further 5 min and results in the deposition of the desired layer 22 of zrcn of typically 0 1 to 0 2 u03bcm thickness the zr target is operated here in the arc evaporation mode once the zrcrn layer has been completed the articles 14 have been provided with the required coating and can be removed from the apparatus they now typically have a golden colour given by the coating materials selected first of all rather than depositing just a single layer of crzrn and a single layer of zrcn a plurality of alternating layers of crzrn and zrcn can be deposited by alternatively switching between the process steps e and f which are then operated for a shorter period of time for each layer of the coating e g for 1 minute per layer secondly it is possible to deposit the coatings in the steps e and f by operating the targets in the cathode sputtering mode this is done by adjusting the process conditions to values suitable for operation as an imbalanced magnetron suitable values are given in the above mentioned document ep a 0 439 561 moreover it is not necessary for the coatings of steps e and f to be both deposited by the arc deposition mode or both by the cathode sputtering mode one coating can be applied by the one method and the other coating by the other method it should also be mentioned that the coating quoted here is simply one coating by way of example other coatings known per se can readily be used the important consideration is the provision of the cr layer to act as a water diffusion barrier if another material is used in the coating scheme then target 30 can be formed.