PLASMA AND ION-BEAM-ASSISTED DEPOSITION OF MULTILAYERS FOR TRIBOLOGICAL AND CORROSION PROTECTION

Multilayers of Ti/TiN and Al/AlN were deposited on steel and silicon by magnetron sputtering and ion-beam-assisted deposition. Compositions and film thicknesses were determined by Rutherford backscattering. Hardness was measured with a dynamic ultramicrohardness tester. The corrosion protection potential in an aqueous environment was evaluated by electrochemical techniques. The results are discussed in terms of the structure and composition of the multilayer arrangement. It turns out that the multilayer coatings generally show a better corrosion protection performance than both the pure metal and the pure nitride films, with an optimum ratio of nitride film thickness to metal film thickness for a maximum corrosion protection effect. The hardness values are in between that of nitride single film and those of metal single films. Deposition of multilayers with the possibility of selecting the thickness ratio of metal to nitride film for particular mechanical and chemical requirements allows a controlled adaption of the film features to a given application problem.