scholarly journals MULTILAYER COMPOSITE PLASMA COATINGS ON SCREEN PROTECTION ELEMENTS BASED ON ZIRCONIUM DIOXIDE

2017 ◽  
Vol 16 (5) ◽  
pp. 422-431 ◽  
Author(s):  
V. A. Okovity ◽  
F. I. Panteleenko ◽  
V. V. Okovity ◽  
V. V. Astashinsky ◽  
P. P. Hramtsov ◽  
...  
Keyword(s):  
Surface Layer ◽  
Zirconium Oxide ◽  
Zirconium Dioxide ◽  
Fractional Composition ◽  
Lattice Parameter ◽  
Plasma Formation ◽  
Plasma Flows ◽  
Compression Plasma Flows ◽  
Melted Layer ◽  
Scanning Electron

The paper contains results of investigations pertaining to an influence of plasma jet parameters (current, spraying distance, consumption of plasma formation gas (nitrogen)), fractional composition of initial powder and degree of cooling with compressed air on anti-meteoric coating characteristics. Optimum modes (arc current 600 A; spray distance of 110 mm; consumption of plasma formation gas (nitrogen) – 50 l/min; fractional composition of zirconium dioxide powder <50 μm; compressed air consumption for cooling – 1 m3/min; p = 4 bar) make it possible to obtain anti-meteoric coatings based on zirconium dioxide with material utilization rate of 62 %, total ceramic layer porosity of 6 %. After exposure of compression plasma flows on a coating in the nitrogen atmosphere a cubic modification of zirconium oxide is considered as the main phase being present in the coating. The lattice parameter of cubic zirconium oxide modification is equal to 0.5174 nm. Taking into consideration usage of nitrogen as plasma formation substance its interaction with zirconium coating atoms occurs and zirconium nitride (ZrN) is formed with a cubic crystal lattice (lattice parameter 0.4580 nm). Melting of pre-surface layer takes place and a depth of the melted layer is about 8 μm according to the results of a scanning electron microscopy. Pre-surface layer being crystallized after exposure to compression plasma flows is characterized by a homogeneous distribution of ele-ments and absence of pores formed in the process of coating formation. The coating structure is represented by a set of lar- ge (5–7 μm) and small (1–2 μm) zirconium oxide particles sintered against each other. Melting of coating surface layer and speed crystallization occur after the impact of compression plasma flows on the formed coating. Cracking of the surface layer arises due to origination of internal mechanical stresses in the crystallized part. While using a scanning electron microscopy a detailed analysis of the surface structure has permitted to reveal a formation of a cellular structure with an average cell size of less than 1 μm in the crystallized portion and formation of the cells can be caused by speed crystallization of the melted layer.

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

2018 ◽  
Vol 17 (5) ◽  
pp. 378-389 ◽  
Author(s):  
V. A. Okovity ◽  
F. I. Panteleenko ◽  
V. V. Okovity ◽  
V. M. Astashinsky ◽  
V. V. Uglov ◽  
...  
Keyword(s):  
Surface Layer ◽  
Zirconium Dioxide ◽  
Composite Coatings ◽  
High Energy ◽  
Morphological Properties ◽  
Multilayer Composite ◽  
Plasma Flows ◽  
Near Surface ◽  
Compression Plasma Flows ◽  
X Ray

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.

FORMATION OF Nb-CONTAINING ALLOYS IN THE SURFACE LAYER OF MATERIALS BY COMPRESSION PLASMA FLOWS

2015 ◽  
Vol 19 (2) ◽  
pp. 153-167 ◽  
Author(s):  
Nikolai Cherenda ◽  
Andrej K. Kuleshov ◽  
Vitali I. Shymanski ◽  
Vladimir V. Uglov ◽  
N. V. Bibik ◽  
...  
Keyword(s):  
Surface Layer ◽  
Plasma Flows ◽  
Compression Plasma Flows

STRUCTURE OF THE AUSTENITIC STEEL SURFACE LAYER SUBJECTED TO COMPRESSION PLASMA FLOWS IMPACT

2020 ◽  
Vol 24 (3) ◽  
pp. 211-225
Author(s):  
Nikolai N. Cherenda ◽  
Vladimir V. Uglov ◽  
Yu. V. Martinovich ◽  
I. A. Betanov ◽  
Valiantsin M. Astashynski ◽  
...  
Keyword(s):  
Surface Layer ◽  
Austenitic Steel ◽  
Steel Surface ◽  
Plasma Flows ◽  
Compression Plasma Flows

scholarly journals Multielemental alloying of steel surface layer under the action of compression plasma flows

2019 ◽  
Vol 1238 ◽  
pp. 012057
Author(s):  
N N Cherenda ◽  
V V Uglov ◽  
G M Dzagnidze ◽  
V M Astashynski ◽  
A M Kusmitski
Keyword(s):  
Surface Layer ◽  
Steel Surface ◽  
Plasma Flows ◽  
Compression Plasma Flows

Modification of the structure of the hypereutectic silumin alloy Al-44Si under the action of compression plasma flows

2021 ◽  
Vol 1 ◽  
pp. 40-50
Author(s):  
V.I. Shimanski ◽  
◽  
A. Evdokimovs ◽  
V.V. Uglov ◽  
N.N. Cherenda ◽  
...  
Keyword(s):  
Energy Density ◽  
Elemental Composition ◽  
Phase State ◽  
Primary Silicon ◽  
High Energy ◽  
Absorbed Energy ◽  
Plasma Flows ◽  
Compression Plasma Flows ◽  
Silicon Crystals ◽  
Melted Layer

Effects of the high-energy compression plasma flows on the structure, elemental composition, and phase state of Al-44 at.% Si hypereutectic silumin alloy have been investigated. Using scanning electron and optical microscopy it was found decreasing in grain size of both primary silicon particles and Al-Si eutectic parts with increase of absorbed energy density of compression plasma flows. The primary silicon crystals were dispersed down to 300 nm in the result of high cooling rate of the melted layer after its homogenization by means of hydrodynamic mixing. It was found that increase in the absorbed energy density, homogenization of elemental composition in the modifies layer occurs due to increase in lifetime of the melted state and more efficiency mixing process.

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