Corrosion resistance and antifriction properties of nitride multilayered coatings on the basis of V and Ta

Abstract

The analysis of single-layer and multi-layer nitride coatings based on refractory metals V and Ta was conducted. The magnetron deposition based on direct current and targets of the V and Ta with a purity of 99,995 % were used to create the coating samples. The coating deposition was performed in an atmosphere of Ar/N 2 mixture at a substrate bias voltage from 0 to 150 V. The changes of the ratio flow Ar/N2 allowed to form an amorphous (a-TaN) and FCC crystalline (c-TaN) phase of the coating. The tribological tests of single-layer coatings based on Ta showed the presence of chips and cracks at early stages of testing, for c-TaN typical abrasive wear mechanism. The heterostructure system a-TaN/c-TaN has a cohesive mechanism of wear and better adhesion to the substrate, rather than single-layer coatings. An analysis of corrosion re-sistance of the nanostructured coating NV, deposited on a steel substrate RUS-3 at 400 °C was made. For the analysis of the corrosion resistance of the coating unused NV the method of electrochemical impedance spectroscopy technique in 3.5 % solution of NaCl was used. The applied negative voltage to 150 V results to increasing coating hardness and elastic modulus, together with the pores, cracks and macro defects are formed on the coating surface that leads to deterioration of corrosion resistance of the system.