Yaroslav Kravchenko

Structural features of the multilayer nitride coatings formation

The features of structure and properties formation of multicomponent (high-entropy) and multilayer transition metals nitride coatings of deposited by reactive magnetron (HF and DC) sputtering of targets in Ar + N2 mixture atmosphere was analyzed. It is shown that the formation of texture and columnar structure of films occurs due to changes the deposition conditions. Moreover, transition metals nitride films (TiN, HfN, et al.) have textured growth plane (111) and nanohardness values about 36 GPa at close to stoichiometric compositions. X-ray analysis of nitride multilayer coatings shows that the multilayers have a cubic structure with a preferential orientation (111) or (200) depending on the period of modulation Λ. It is shown that one of the methods of its preparation is the use of elements (Zr,Y). Correlations between structure and physico-mechanical properties of the coatings, as well as the effect of multilayers deposition conditions and modulation period on the hardness value were exhibited. Conducted researches show that the use of multi-component and multi-layered nitride coating allows to obtain super hard nitride coating (> 40 GPa,) with high elastic recovery (We up to 83%) and high resistance to plastic deformation (H3/E*2 up to 0.75).

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

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/N2 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.