English English

Bragina L.L.

Doctor of Engineering Sciences (Advanced Doctor), Professor, Kharkiv Polytechnic Institute, Ukraine

A BLOCK OF THERMAL INSULATION MATERIALS WITH PROTECTIVE AND DECORATIVE COATINGS

https://doi.org/10.34031/2618-7183-2019-2-1-4-10
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 4-10 p.
Abstract
Scientific and technological principles of alternative plasma technology for the production of two-layer heat-resistant glass-like decorative coating were developed. The compositions of the intermediate heat-resistant layer and the technology of its application to the surface of the enclosing block of foam glass are proposed. The optimal parameters of plasma melting of heat-resistant and decorative coating layers were determined. The influence of high-speed characteristics of plasma jet thermal melting on the formation of texture and performance of two-layer heat-resistant coating is established. The features of the formation of amorphous vitreous and glass-crystalline phases of a two-layer heat-resistant coating are presented. Using x-ray phase analysis, the features of the phase composition of different layers of heat-resistant coating, as well as the laws of formation of its structural elements are studied. Based on the analysis of significant experimental material, it was concluded that the formation of the upper amorphous layer with liquating regions and minor gas inclusions. The conducted researches allowed to reveal and justify the features of the structure of the layers lying under the amorphous liquating. It was found that the two-layer protective and decorative coating had high physico-chemical and physico-mechanical properties: adhesion strength to the matrix of the foam glass block-1.25 ± 0.05 MPa, microhardness-785 HV, heat resistance-122°C, acid resistance – 98.5%, alkali resistance – 95.4%.
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SHEET BUILDING GLASS WITH PROTECTIVE AND DECORATIVE COATINGS

https://doi.org/10.34031/2618-7183-2019-2-1-11-16
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 11-16 p.
Abstract
Sheet glass with decorative coatings in industrial and civil construction play an important role in improving the aesthetic properties of buildings for various purposes. An innovative technology for obtaining decorative coatings on sheet glasses using low-temperature plasma is proposed. For plasma spraying crushed in a ball mill container glass of various colors was used. The optimal parameters of the plasma spraying of glass powders on the front surface of the glass sheets were established. To increase the adhesion strength of the coating to the substrate before plasma spraying, the front surface was heat treated with outgoing plasma-forming gases. It was found that with increasing temperature of the outgoing plasma-forming gases and the time of their impact on the front surface of the sheet glass, the adhesion strength of the coating with the base increases to 6.7 MPa. The effect of the coating thickness on the strength of its adhesion to the substrate is studied. Increasing the coating thickness from 150 to 1000 µm reduces the adhesion strength from 7.5 to 3.2 MPa. Under the influence of high temperatures of arc plasma is not only an increase in the glass refractory oxides of silicon and aluminum, but also an increase in their hardness up to 15%.
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VITREOUS PROTECTIVE AND DECORATIVE COVERINGS ON WOOD PARTICLE BOARD

https://doi.org/10.34031/2618-7183-2018-1-4-4-12
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 4-12 p.
Abstract
Scientific and technological bases of receiving vitreous coverings on wood with use of a torch of low-temperature plasma are developed. Before plasma dusting of glass powders by grain structure 60-120mkm, the special protective coating protecting chipboard from destruction at high-temperature influence of a plasma stream on a front surface of the wood particle board (WPB) was applied. The structure of an intermediate protective coating including mix of a fine-grained glass powder and liquid glass is developed. Preliminary drawing an intermediate protective layer provides several consecutive technological operations.
For receiving vitreous coverings fight of colored and colourless glass are used which was previously ground in spherical porcelain mills. Optimum process parameters of plasma dusting of glass powder on the front surface of chipboard are developed. Optimum parameters of plasma melting is: current - 800A; operating voltage – 30B, a consumption of plasma-forming gas of argon 2m3/h.
Operational and aesthetic-consumer properties of vitreous protective and decorative coverings are investigated. It is established that vitreous protective and decorative coverings have the high durability of coupling with an intermediate protective layer. The received vitreous protective and decorative coverings on the basis of colored and colourless glass have the high water resistance, acid resistance, alkali resistance, as well as microhardness and high aesthetic performance.
The technology is recommended for widespread industrial introduction.
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TECHNOLOGY OF PLASMA METALLIZATION OF THE WOOD AND FIBROUS BOARD

https://doi.org/10.34031/2618-7183-2018-1-3-4-10
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 4-10 p.
Abstract
The scientific and technological principles of metallization of products on the basis of wood with use of plasma high-temperature dispersion are developed. For the purpose of prevention of impact of the highest temperatures of a plasma stream on a front surface wood and fibrous board (fibreboard) an intermediate layer was put.
The structure of an intermediate protective layer, the including mix of epoxy resin with refractory filler is developed. Operation of drawing a protective intermediate layer included several specially developed technological stages. For the subsequent metallization such non-ferrous metals as copper and aluminum in the form of a wire are used. Optimum parameters of plasma dusting of metals on a front surface of a fibreboard are determined
The protective and decorative covering on the basis of non-ferrous metals had high aesthetic consumption and performance properties. The covering possessed the increased coefficient of diffusive reflection and high durability of coupling with a matrix. The dependence of influence of thickness of the raised dust metal covering on durability of coupling of a covering with a substrate is established.
The developed technology of metallization of products from wood in comparison with traditional technologies, allows to lower significantly time of metallization and energy consumption and to increase competitiveness of products both on internal, and on external the markets.
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INVESTIGATION OF INFLUENCE OF PLASMOCHEMICAL MODIFICATION ON MACRO- AND MICROSTRUCTURE OF SURFACE LAYER OF AUTOCLAVE WALL MATERIALS

https://doi.org/10.34031/2618-7183-2018-1-2-4-10
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 4-10 p.
Abstract
Studies of the high-temperature effect of a plasma torch on the formation of a multilayer structure of the protective and decorative coating of autoclave wall materials are presented. The tasks of the work included studies: a temperature gradient in a multilayer protective-decorative coating; chemical composition of the fused, intermediate and deep layers of the protective and decorative coating; influence of sodium liquid glass on the formation of macro- and microstructures of protective and decorative coatings under the influence of plasma; processes of thermal diffusion and redistribution of oxides in the fused, intermediate and deep layers.
It was found that when the plasma torch was treated with autoclave wall materials, the surface layer was heated to a depth of 3000 μm, and the maximum surface temperature reached 2000 °C. The pattern of the change in the structure of the fused and intermediate layer is revealed. It is shown that the preliminary impregnation of the surface of silica brick during plasma treatment due to the formation of a low-melting melt eliminates microcracks in its deep layers, and high plasma temperatures promote intensive evaporation of sodium and calcium oxides from the fused layer.
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PLASMOCHEMICAL MODIFICATION OF WALL BUILDING MATERIALS

https://doi.org/10.34031/2618-7183-2018-1-2-11-18
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 11-18 p.
Abstract
The aim of the work is to study the effect of a high-temperature plasma torch on the processes of phase transformations and layer-by-layer modification of the protective and decorative coating on concrete using as a filler a mixture of quartz sand and hollow glass microspheres. The main tasks included: investigation of the processes of evaporation and thermal diffusion of oxides of plasma-coated coatings; study of phase transformations in the melt and its subsequent crystallization in the process of rapid spontaneous cooling of the fused protective and decorative coating; study of the effect of sodium liquid glass on the processes of polymorphic transformations of alumina and the formation of micro-wicks due to the intense diffusion of sodium oxide; study of operational characteristics of protective and decorative coatings. It was established that the initial phases in the protective-decorative coating are α-Al2O3 and CaO∙6Al2O3 (β-Al2O3), and the liquid sodium glass in the coating leads additionally to the formation of Na2O∙11Al2O3. The top layer of the protective and decorative coating is Na–Ca–Al–Si glass with regions of heterogeneities containing an increased content of sodium oxide. The content of aluminum oxide in the protective and decorative coating based on the battle of high-alumina refractory was 95.1 %. The introduction into the coating composition of sodium liquid glass minimizes the processes of dehydration of the binding component and changes the chemical composition of the protective and decorative coating. Reduction of the aluminum oxide content to 83.0 % affects the microhardness indicators. Microhardness of the concrete surface due to the introduction of liquid glass is reduced from 2510 HV to 887 HV.
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