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The paper presents results of studying structure and properties of multilayer composite coatings optimized for their composition based on zirconium dioxide materials used for deposition of plasma coatings on the models of elements for anti-meteor shielding screens. The influence of plasma jet parameters (current, distance of sputtering, consumption of plasma-forming nitrogen gas) and fractional composition of an initial powder on characteristics of two-layer composite coatings based on nickel-chromium-aluminum-yttrium and zirconium dioxide on the elements of protective screens has been analyzed in the paper. Optimization has been carried out on the basis of obtaining maximum coefficient of powder utilization. The investigations have made it possible to ascertain specific features of elemental and phase composition, surface morphology, microstructure multilayer composite coatings on the basis of a solid layer of metal oxides and a viscous transition sub-layer subjected to compression plasma flows. The investigations have been executed with the help of scanning electron microscopy, energy dispersive x-ray spectral microanalysis, and x-ray diffraction analysis. It has been shown on the basis of the obtained results that the effect of compression plasma flows on multilayer composite coatings leads to a modification of a near-surface layer with a thickness up to 15 μm that presupposes its melting and subsequent high-speed crystallization which together provide an increase in its density, decrease in porosity while maintaining the initial phase state. Liquid-phase processes in the molten phase of the near-surface layer permit to modify morphological properties of the surface which are associated with its smoothing and lowering of roughness.

This paper presents a mathematical model of the plasma-spray coating formation process that allows one to estimate bond strength energy, a parameter related to coating quality. Bond strength energy is defined on the basis of particle-substrate or system balance. Unknown quantities in the energy equation are obtained from nonstationary Navier-Stokes equations for velocity field and pressure and from thermoelasticity equations for temperature and stress. Complexities associated with particle spreading and nonlinear hydrodynamics have made it necessary to develop a stable numerical technique.

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abstract. A quick cooling of coatings for the forming of the electrolyte layers with the given phase composition is widely used. In this work the preliminary heating of the specimens was applied instead of quick cooling technology. The influence of the substrate preliminary heating on the ZrO 2 -Y 2 O 3 coatings structure and properties was investigated. The optimal of the spraying of coatings from the Ni and ZrO 2 -Y 2 O 3 powders mechanical mix was determined. The research on the coating structure was carried out analysing the application of the optical metallography, scanning microscopy and X-ray method.