Formation and Research of Multi-Layer Composite Plasma Oxide Coatings Based on Elements of Screen Meteroid Ptotection

Пантелеенко, Ф. И.; Девойно, О. Г.; Оковитый, В. А.; Асташинский, В. М.; Khramtsov, P. P.; Черник, М. Ю.; Углов, В.В.; Соболевский, С. Б.

doi:10.21122/2227-1031-2016-15-5-357-364

Cited by 4 publications

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“…Однако увеличение концентрации реактивного элемента ограничено процессами охрупчивания сплава и ростом скорости диффузии кислорода [7][8][9][10]. Поэтому большинство MеCrAlY-сплавов имеют ограничения по содержанию кислорода до 0,05 %, и в качестве основных методов нанесения покрытий представляется целесообразным использовать вакуумные методынапыление в динамическом вакууме (VPS) или электронно-лучевое физическое осаждение в вакууме (PVD) [5,[11][12][13]. Но поскольку это очень дорогое и редкое оборудование, для отработки технологий нанесения ТЗП в лабораторных условиях мы предлагаем использовать специальную насадку с контролируемой атмосферой, применение которой при напылении жаростойких подслоев способствует минимальному содержанию кислорода в зоне напыления.…”

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Plasmatron for Coatings

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The paper analyzes reasons for application of plasma torches of special design for deposition of heat-resistant layers of thermal barrier coatings that contribute to minimum oxygen content in the zone of spraying. It contains detailed description of design for a plasma torch with a nozzle that allows better protection of a plasma stream against atmospheric exposure.Heated inert gas (Ar) is fed inside the nozzle along its walls through holes in its end part. Air around a plasma jet is displaced, additional compression of the plasma occurs and due to this oxygen content is decreased in a coating and efficiency of material deposition is increased. An additional use of a tungsten insert in an electronic node makes it possible to create a pair of tungsten – tungsten in an electrode assembly and the life of the electrode assembly will be increased due to high erosion resistance, electrical conductivity, thermal conductivity and sufficient strength in 2–2.5 times while increasing spray performance through toughening regimes. The paper presents testing results of the developed plasma torch and its prototype for duration of continuous operation and intensity at 500 A current, 70 V voltage, nitrogen flow rate of 45 l/min (standard mode for deposition of oxide ceramics). Coatings from nickel–chromium–aluminum–yttrium powder have been obtained while using plasma torches with the same parameters of deposition and a comparative analysis of the technological properties have been made in the paper. The developed plasma torch has more qualitative characteristics of subsurface plasma coatings: increase in adhesive strength – by 1.4 times, material utilization ratio – by 1.3 times, micro-hardness – by 1.3 times, porosity decrease – by 2.3 times.

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FORMATION AND STUDY OF PLASMA SPRAYING DOUBLE-LAYER COMPOSITE COATINGS (VISCOUS METALLIC NiCr AND SOLID ZrO2 LAYER)

et al. 2018

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. The paper presents results pertaining to investigations on influence of plasma jet parameters and fractional composition of initial powder on characteristics of two-layer composite coatings on the basis of nickel-chromium, and zirconium dioxide in the shielding elements. Optimization has been carried out on the basis of obtaining maximum powder use factor. A comparative analysis for dependence of the powder use factor in viscous metal layers of nickel-chrome and nickelaluminum on spraying distance shows that while having similar character of curves for the presented dependencies an absolute value of powder use factor is higher for nickel-chromium powder. It can be explained by a higher ductility of the latter and correspondingly smaller rebound of particles which are colliding with substrate. The investigation results for cross section microstructure in the formed coatings while using scanning electron microscopy are given in the paper. The paper considers cross section microstructures for ZrO2-coating and intermediate Ni–Cr layer. The submitted data reveal that an initial stage of the coating is characterized by porosity and an average pore size is of several micrometers, and in some areas its size reaches 20 mm. The microstructure of a Ni–Cr layer is characterized by lower porosity. Impact of compression plasma flows on sprayed coating leads toformation of fused oxide layer with thickness of 12–15 mm and contributes to smoothing of surface relief and formation of cracks on the surface which are preferably propagating into coating depth. Processing of oxide coatings by compression plasma also results in reduction of their porosity.

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Formation and Investigation of Plasma Powder Coatings Made of Oxide Ceramics Modified with High-Energy Effects

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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.

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Formation and Research of Multi-Layer Composite Plasma Oxide Coatings Based on Elements of Screen Meteroid Ptotection

Cited by 4 publications

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Plasmatron for Coatings

FORMATION AND STUDY OF PLASMA SPRAYING DOUBLE-LAYER COMPOSITE COATINGS (VISCOUS METALLIC NiCr AND SOLID ZrO2 LAYER)

Formation and Investigation of Plasma Powder Coatings Made of Oxide Ceramics Modified with High-Energy Effects

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