DEPOSITION OF ADHERENT HARD COATINGS ON STEEL BY PLASMA-ENHANCED CVD

Wear resistant TiNx- and TiCxNy-layers were deposited on various pretr eated steel substrates in the temperature range 673-773 K. The influen ce of the process parameters and substrate pretreatment on the deposit ion rate, layer composition, interface and layer structure, microhardn ess and stress have been investigated. With optimized process paramete rs, layers with a low oxygen and chlorine impurity content, high micro hardness and a good adhesive strength are obtained. Usually, the TINx- and also the TiCxNy-layers with low carbon content deposited at 773 K have a columnar structure with a [200] texture. Nevertheless for TiCx a [111] texture is observed. TiNx-layers prepared below 773 K have a [111] preferred orientation or they are textureless. The adhesion of t he coatings on plasma nitrided steel substrates is remarkably higher t han on non-nitrided substrates. The critical loads for nitrided and no n-nitrided S6-5-2 steel are 44 N and 14 N, respectively.