COMPARATIVE ANALYSIS OF STRUCTURE FORMATION AND PROPERTIES OF PVD COATINGS TIN, TI/TIN AND TIN-MON

Abstract

Nanocomposite coatings represent a new generation of mate-rials and they consist of at least two phases with a nanocrystalline and/or amorphous structure. They have a lot of unique properties, the appear-ance of which is associated with a high volume fraction of phase boundar-ies, with the strength of these boundaries, with the absence of dislocations inside crystals. The purpose of the paper analysis of the reasons for the observed changes, based on the mechanism of formation of surface lay-ers of vacuum-arc coatings under the condition of implantation processes stimulated by applying a negative potential to the substrate. Methodology. All samples were obtained using modern coating methods on a modernized "Bulat-6" installation. Cross section imagines were carried out by meth-ods of optical, electron microscopy. Structure of the samples was studied using a "DRON-3M" instrument in Cu-Kα radiation. Separation of diffrac-tion profiles was carried out using the "New profile". Mechanical tests of materials were performed in the mode of microindentation. Results. At all schemes of deposition of TiN coatings, a single-phase state with an fcc lattice is formed. As the displacement potential increases, a transition from [100] to [111] texture is observed. In multilayer nanostructured TiN/Ti coat-ings, a texture develops in titanium nitride layers with a thickness of 300 nm or more when a displacement potential is applied [111]. The thickness of the Ti layers of more than 30 nm is sufficient for the development of the stress-strain state in the TiN layers without their significant relaxation. When the displacement potential increases, the macrostress of the compression in the titanium nitride layers of TiN increases. It was established that epitaxial growth of isostructural cubic modifications of titanium nitride and molybdenum nitride without the formation of a two-phase state is possible with a small thickness of layers in the TiN-Mo2N multilayer system (≈2 nm). At a greater thickness, a two-phase material is formed, where the second phase is high-temperature molybdenum nitride γ-Mo2N with a cubic lattice, which is isostructural to titanium nitride. Practical implications. The final properties of nanocrystalline coatings such as the size and orientation of the grains, the structure strongly depend on the technological parameters of deposition – ion bombardment, shear potential, temperature of the sub-strate, flow density and energy of the precipitating ions, therefore, in order to achieve the desired results in each specific case, it is necessary to strive for optimization of the process deposition of coatings. Value/originality. A possible mechanism for the formation of micro- and nanostructured lay-ered condensates under conditions of continuous influence of condensation of accelerated particles of the deposited flow is proposed. At the same time, the surface is subject to bombardment, which is based on radiation-stim-ulated processes of redistribution of elements of the deposited flow and structural defects of the coating material that is formed.