The influence of the layer thickness (in the nanometer range) and negative bias potential (-Us) supplied during the deposition on the structure and hardness of the composite vacuum-arc coatings are analyzed for multilayer ZrN/CrN system with a large difference in the atomic weights and radiation-induced defect formation of metal components. It is established that at the layer thickness less than 50 nm, supply of-Us leads to an increase of microstrain in the CrN layers under bombardment by Zr ions with large atomic radius and mass, and the strain relaxation is observed in ZrN layers. The observed effects are explained by an increase in energy of deposited ionized particles when applying-Us that determines the radiation-induced mixing at the interphase boundaries of the layers and leads to the hardness decrease. The highest hardness of 42 GPa in the ZrN/CrN system is achieved upon deposition of thin (20 nm) layers in the absence of-Us.

The possibilities of structural engineering of multi-period vacuum-arc coatings based on nitrides of transition metals Ti, Cr, Mo, and Zr have been investigated by structural studies (X-ray diffraction and electron microscopy) in combination with measurement of hardness by indentation. The formation of phases with a cubic crystal lattice under nonequilibrium conditions under vacuum arc method of production. The supply of a negative bias potential of-200V in mononitrides leads to the predominant formation of texture of crystallites with the [111] axis. The introduction of thin (about 10 nm) metal layers leads to a decrease in texture perfection [111] and texture formation [100]. This effect is associated with a change in the stress-strain state of nitride layers. It is determined that the composite multiperiod coatings (Me1N/Me2N)/(Me1/Me2) have a greater hardness and greater resistance compared to MeN/Me. For a multiperiod system with damping metal layers-(ZrN/CrN)/(Zr/Cr), superhard coatings with a hardness of 46 GPa were obtained.

Using the method of structural engineering by changing the thickness of the layers in a multiperiod ZrN/MoN system investigated the effect of the phase-texture state of the crystallites and their size on the hardness of the vacuum-arc coating. Is revealed a determining influence on the formation of ZrN layers preferential orientation growth [100] axis with a small layer thickness 7-20 nm (the deposition of 3 to 10 seconds). At high layer thickness determines the texture [311] crystallites are -Mo2N phase formed in the Mo-N layers. Pulsed high-voltage stimulation without changing the type of structural states for different layer thicknesses, leads to partial disorientation texture in thick layers. Hardness of coating with thick (80 nm) layers is 35-37 GPa. In small thickness layers pulse stimulation of atoms motility causes the formation of a planar structure with an average crystallite size of 4-9 nm in the layers, which is accompanied by increased hardness of up to 44 GPa.

Influence of the period value Λ (at different negative potential Ub that supplied during deposition) on phase composition, structure, stress-strain state and hardness of multiperiod coatings ZrNx/MoNx is investigated by using complex methods of validation structural state at combined with microindentation. Formation in layers ZrNx and MoNx the phases with cubic lattice and preferred orientation of crystallites with axis [100] is established. Stress-strain state of compression with increasing Ub is amplified and reaches maximum value (-6.7 GPa) at Λ  20 nm and Ub -110 V. Hardness of coating increases with decreasing Λ from 300 to 20 nm. Coatings that obtained with Λ  20 nm and Ub -110 V have the highest hardness 44 GPa. Relaxation of structural compressive stresses and decreasing hardness is happening at smaller Λ and larger Ub -110 V (as a result of radiation-stimulated forming defect and mixing). Data of computer modeling of defectiveness at atomic level at bombardment of ions that accelerated in field Ub are used to explain the results.

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The influence of the layers thickness of bilayer multi-period coatings of the CrNx/MoNx and CrNx/TiNx systems on their phase-structural state, substructure, stress-strain state and mechanical properties was studied using methods of precision structural analysis in combination with computer simulation of implantation processes during particle deposition. It is established that a two-phase structure of CrN and -Mo2N phases of the structural type NaCl is formed in the multi-period coatings of the CrNx/MoNx system with a nanometer thickness of the layers. Because of the small difference in periods (less than 0.5 %) for Λ  20 nm, the layers form a coherent interlayer interface. The use of small Ub -20 V during deposition makes it possible to avoid significant mixing at interlayer (interphase) boundaries even at the smallest Λ  10 nm. Nitride layers formed under conditions of vacuum arc deposition are under the action of compressive stresses. In the СrNх/TiNх system, because of the relatively large discrepancy between periods (more than 2.5 %), during the formation of the same structural components in the layers (CrN and TiN phases of the structural type NaCl), the epitaxial growth with period adjusting does not occur, even for the smallest Λ  10 nm. The action of the deformation factor at the interphase boundary allows achieving an ultrahard state (with a hardness of about 50 GPa), which causes a relatively low friction coefficient. The obtained results on the formation of phase-structural states with the nanoscale thickness of layers of multi-period nitride coatings are explained from the position of minimization of surface energy and deformation energy.

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