Structure and Tribological Properties of AlCrN plus CrCN Coating

The paper presents results of the investigation of the AlCrN and AlCrN + CrCN coatings, deposited by arc evaporation method on the austenitic steel substrate. Topography studies performed with the use of AFM showed that the roughness value was 24 nm for AlCrN and 14 nm for CrCN. Chemical analysis carried out with energy dispersive X-rays spectroscopy confirmed the chemical composition of the coatings. Transmission electron microscopy (TEM) investigations showed a column structure of AlCrN and CrCN layers with a width in the range of 10-200 nm. Tribological properties analyzed using a scratch test and ball-on-disc method showed a good adhesion of the coatings to the substrate (L-C2 is 40 and 46 N for AlCrN and AlCrN + CrCN, respectively) and its high wear resistance; the use of an additional CrCN layers caused a decrease in the friction coefficient by 19%. Structure modification of the AlCrN + CrCN coating system and the related improvement in its mechanical and tribological properties allowed increasing the lifetime of the coated elements. The original approach was to produce a dual-layer coating, consisting of an internal, hard AlCrN layer and an external layer of CrCN, providing good tribological properties, as well as an appropriate forming of the transition zone between the layers.