Structural State and Properties of Composite Chromium Coatings Modified with Nitrogen Ions

The structure, durometric properties, wear resistances, and corrosive dissolution of composite chromium coatings modified with nanodimensional carbon-containing additives and treated with nitrogen ions are investigated. It is demonstrated that addition of nanodimensional carbon-containing particles to the deposition electrolyte leads to dispersion of the crystal structure of the coatings. This is accompanied by their hardening and increase in the wear and corrosion resistances. When the composite chromium coatings are treated by nitrogen ions, nitrided layers are formed containing Cr2N and CrN nitrides. It is demonstrated that ion-beam nitriding of the composite chromium coatings provides relatively higher concentration of nitrogen in the layer compared to the conventional chromium coating. Formation of the nitride layer on the surface of the composite chromium coating leads to an increase in its microhardness and additional decrease by 24% of the rate of corrosive dissolution of the coatings. Softening of the chromium substrate during ion-beam nitriding causes a decrease in the wear resistance of the composite chromium coatings under conditions of friction without lubricant.