Heat-resistant Coatings Research Articles

Повышение свойств плазменных теплозащитных покрытий за счет напыления материалов, реагирующих с экзотермическими эффектами

The quality of heat-resistant coatings deposited by flame spraying is largely determined by the adhesion of the coating to the surface of the part. One of the ways to increase adhesion is to deposition intermediate layers of thermosetting powders between the base material and the coating. In this work, two versions of heat-protective coatings are investigated — a two-layer coating consisting of an Al – Ni sublayer (20 – 80 wt. %) and a main ZrO2 layer, and a single-layer coating sprayed from an aluminum-clad zirconium oxide powder (20 ZrO2 – 80 Al, wt. % ). The method of differential thermal analysis was used to determine the temperature ranges and values of the exothermic effects of oxidation and redox reactions during heating of Al – Ni and ZrO2 clad powders. A significant exothermic effect was found during oxidation of the aluminum cladding shell in the temperature range of 360 °C and a stronger thermal effect due to the redox reaction at a temperature of 920 °C. The microstructure and microhardness of the obtained coatings have been studied, and their thermal conductivity and adhesion have been assessed. The resistance of the coatings during thermal cycling tests has been determined. It has been established that thermal protective coatings made of aluminum-clad zirconium oxide powder have the best characteristics under thermal cycling conditions. A higher level of adhesion and thermal cyclic resistance of such coatings are due to an increase in the enthalpy of aluminum-clad ZrO2 powders due to exothermic reactions and the presence of a metal binder.

Effect of Heat Resistant Coating on the Drilled Hole Quality of Hybrid Fiber Reinforced Epoxy Composite

Effect of Heat Resistant Coating on the Drilled Hole Quality of Hybrid Fiber Reinforced Epoxy Composite

Deposition of heat-resistant coatings based on the ZrSi2-MoSi2-ZrB2 system for protection of non-metallic composite materials in high-speed high-enthalpy gas flows

The work demonstrates possibility of formation of coatings based on the ZrSi2-MoSi2-ZrB2 system by the slip-firing method. During oxidation, the coatings form heterogeneous oxide film resistant to high-speed high-enthalpy gas flow due to generation of refractory ZrO2 framework filled with borosilicate glass doped with zirconium dissolved in it. The advantages and disadvantages of the coatings in the system under study are presented.

Synthesis and Properties of Heat Resistant Coatings Based on a Si–B4C–ZrB2–ZrO2 Composition

This article discusses the influence of nanosized particles of zirconium dioxide on the properties of a heat-resistant coating synthesized by the suspension annealing of a silicon–boron carbide–zirconium diboride composition. The heat resistance of coatings on graphite and high silica ceramic substrates is studied, and the phase composition, morphology, hardness, and electric resistance of the coatings are determined.

Heat-Resistant Coatings of ZrB2–MoSi2–SiC on Carbon-Carbon Composite Materials for Aerospace Applications

Heat-resistant slip coatings of the ZrB2–MoSi2–SiC system on CCCM were examined for protection of aerospace technology elements from oxidation. The following compositions (mass%) were studied as coating materials: 55 ZrB2 + 25 MoSi2 + 20 SiC (ZSM25), 50 ZrB2 + 30 MoSi2 + 20 SiC (ZSM30), and 45 ZrB2 + 35 MoSi2 + 20 SiC (ZSM35). Heat-treatment modes were elaborated for the coatings. The optimal method for producing heat-resistant coatings was selected. The ZSM25 coating was found to satisfy the heat-resistance assessment tests conditions in a Multiplaz 2500-m plasmatron for 20 sec at an angle of 45°, presumably by forming a highly viscous ZrSiO4 film.

The study of high-temperature stability of the heat-resisting intermetallide coating

The article presents the results of a study of the processes occurring in a heat-resistant intermetallic coating under ultrafast thermal heating by a laser beam. Workers, guide vanes and other parts of the hot tract of gas turbine engines are operated at elevated temperatures, pressures and speeds. Significantly increase the life of such parts by applying heat-resistant coatings that protect the surface from high-temperature oxidation, erosion, and softening of the base material. The plasma coating consists of an intermetallic (β-phase) compound. A pulsed-periodic laser with pulse energy E = 5, 10, 15, and 30 J was used for thermal heating. Upon heating, surface melting of the fusible phases occurred and the integrity of the surface layer of the coating was violated. By changing the parameters of laser radiation, it is possible to carry out express diagnostics and comparative tests of coatings, as well as to predict their behavior in extreme conditions.

Heat-resistant coatings on CCCM for aerospace applications

Slip coatings of ZrB2‒MoSi2‒SiC system on CCCM of the next compostions, wt. %: 55 ZrB2 + 25 MoSi2 + 20 SiC (ZSM25), 50 ZrB2 + 30 MoSi2 + 20 SiC (ZSM30) and 45 ZrB2 + 35 MoSi2 + 20 SiC (ZSM35) are discussed in the article. The modes of the coatings’ heat treatment were worked out and the optimal method for producing heat-resistant coatings was selected. It was found that the coating of composition 1 satisfies the heat resistance assessment tests conditions on the Multiplas 2500-m plasmatron, presumably working due to the formation of a highly viscous ZrSiO4 film.

The Development of Fire- and Heat-Resistant Coatings Based on Chlorosulfonated Polyethylene with Improved Adhesion to Rubber

The main properties of compositions based on chlorosulfonated polyethylene modified by pyrolyzed polyvinyl alcohol fiber have been investigated. The potentialities of application thereof as coatings with increased fire-and-heat protection and adhesion properties for elastomeric materials is considered.

Heat-resistant coatings on CCCM for aerospace applications

Heat-resistant coatings on CCCM for aerospace applications

Development of gas mixture composition for the improvement of nickel-based cathodes for the ionic-plasma coating

Modern power plants and aero-engines work at enhanceable temperatures that may reach over 1 700 °С. Heat-resistant coatings on the basis of nickel are applied to provide the work at high temperatures. The service life of shoulder-blades, first of all, depends on the quality factors of the coatings (evenness, absence of pores, inclusions, chemical homogeneity). Quality of coating is determined by the application process and quality of cathode. As a rule, cathodes are alloys that are spread with the special geometry. There are a few technologies of making cathodes, with their advantages and defects. One of the methods is ingot melting layer by layer to produce cathodes in copper water-cooled mold with the use of unfluxible electrode. Purpose of research. To enhance the quality of nickel-based cathodes (Ni − Cr − Al − Y) by the improvement of technological modes of ingot melting. The tasks are set to reduce defects such as pores, to increase homogenity of structure and chemical composition. Methodology. The equipment, namely vacuum arc unit, was improved with helium cylinder. Test samples in a way of "pucks" (127 mm in diameter and 40-mm thick) were obtained to study the microstructure and chemical composition. The modes of remelting are worked through. Research of chemical composition was conducted with the use of SEM of РЕМ 106І equipped with microanalysis system. Scientific novelty. Optimal correlation of protective gases on ingot quality factors for further cathode production was identified. At gas correlation of 70/30 % high quality ingots were obtained. Conclusions. Based on the results of research on the effect of the concentration of gas mixture on the structure and composition of cathodes, technological melting conditions were established, which made it possible to improve the quality indicators and economic indicators of the studied cathodes. This will positively affect the number of cathode defects, serviceability of parts that contain coatings and the service life of aircraft engines in general.

Developing the modification of nickel cathodes for applying the ion-plasma coatings on the parts of aircraft engines

This paper reports studying the effect of such highly active, surface-active modifying elements as Y, Hf, and La on the structure and properties of the Ni–Cr–Al system's consumable cathodes, which are used to apply heat-resistant coatings onto the gas-turbine engines' blades. Y, Hf, and La are introduced to form the nanoscale separation of phases that stabilize the alloy structure. In order to obtain cathodes of the required quality, a method of vacuum-arc autocrucible melting has been chosen. The selected technique makes it possible to use raw materials of different dispersity for the manufacture of ingots (in the form of powders or pig metal). The charge was prepared by shredding the materials mechanically, using various methods (cutting and crushing). It has been shown that the introduction of elements such as Y and La into the cathodes has a similar effect on structural formation processes. It has been established that when Hf is introduced, the structure of the resulting consumable cathodes is characterized by a greater degree of homogeneity. There is also a positive effect of Hf on the uniformity of the distribution of doping elements (Al, Cr) in the volume of the material compared to alloy samples modified by Y and La. It has been shown that the introduction of Hf has made it possible to achieve the higher quality indicators in comparison with Y and La. An analysis of coating structure has revealed that samples with Hf have a greater degree of homogeneity and fewer defects, which is especially important when applying coatings of greater thickness (over 40 µm). It has been established that the introduction of Hf makes it possible to apply coatings up to 90 µm thick by obtaining a less defective structure. It has been found that the Hf modification increases the adhesion between the substrate and coating, as well as makes it possible to achieve maximum even distribution of doping elements throughout the entire thickness of the coating applied

Study of Heat Resistant Urethane Varnish Coatings Based on Isocyanate-Containing Prepolymers and Dicyandiamide

The structure and properties of urethane varnish coatings based on isocyanate-containing prepolymers are studied using the methods of atomic force microscopy, thermomechanical analysis, differential scanning calorimetry, and dynamic mechanical analysis. By the modification of isocyanate-containing prepolymers with dicyandiamide, the possibility of producing urethane varnish coatings having different supramolecular structure, high thermal and operational properties is shown.

Heat-Resistant Sitall Coatings for High-Temperature Corrosion Protection of Nichrome Alloys

The bases of physical and chemical processes of technology of heat-resistant Sitall coatings are considered. Presents the results of investigations of phase composition and nanostructure of the contact layer system "nichrome - sitelove coverage" depending on the chemical composition of stellamaris coatings and their mode of microcrystallization. Identified and established the theoretical and technological special-news stalowych formation of coatings on the surface Narumov.

Heat-Resistant CCCM Coatings for Aerospace Applications

The paper discusses the layered heat-resistant coatings for aerospace applications obtained by atmospheric plasma spraying (APS) technique. The following coating material compositions were selected, wt. %: 1 — 20(ZrO2–8Y2O3) + 80MoSi2; 2 — 10(ZrO2–8Y2O3) + 90MoSi2. As the sublayer thickness decreases and MoSi2 content increases, the strength of the coated sample becomes higher. It was established that the coating composition 2 completely satisfies the heat resistance test requirements, and presumably undergoes plastic deformation.

Разработка антиадгезионных фторопластовых покрытий для пищевых технологий

В статье рассматривается актуальный вопрос создания модифицированных полимерных композиций на основе порошкового фторопласта для антиадгезионных термостойких покрытий. В настоящее время сложность создания разделительных покрытий пищевого назначения обусловлена ограниченным выбором полимерных материалов, пригодных для покрытий, контактирующих с продуктами питания, обладающих высокой термостойкостью, а также низкой поверхностной энергией, ответственной за уровень адгезионного взаимодействия с пищевыми средами. Для исследования комплекса структурных характеристик использованы методы сканирующей электронной микроскопии, ИК-спектроскопии. Исследованы как поперечные срезы, так и поверхность покрытий, что позволило установить, что причиной улучшенных механических характеристик модифицированных покрытия является равномерное распределение их по объему, приводящее к гомогенизации структуры, формированию гладкой поверхности покрытий и бездефектной границы раздела «металл-покрытие».

Investigation of the Influence of Technology of Production of Cathodes on the Quality of Condensation Heat-Resistant Coatings

We present the results of comparative investigations of the quality of Me???Cr???Al???Y tube cathodes obtained by the methods of casting and granule metallurgy. The quality of coatings applied to turbine blades by the method of ion-plasma deposition is evaluated by the method of X-ray diffraction microanalysis. The influence of the technology of production of cathodes on the surface roughness of the coatings of turbine blades is analyzed. The surface quality of the blades with heat-resistant coatings deposited with the use of the investigated cathodes is estimated by the method of scanning electron microscopy. We also performed the quantitative analysis of the drop phase with its separation into fractions.

Tribological Wear-Preventive Coatings

This article discusses wear-preventive tribological coatings that increase the operational life of artillery, tank, and rifle barrels. Studies have been conducted using some of them. The presence of a sufficiently large scientific and technical reserve in the field of material science of heat-resistant alloys and antifriction antiwear coatings is noted.

Biosourced heat resistant coatings by cross-linking of proteins with triethyl phosphate

The industrial application of proteins has been limited so far. While there are good possibilities to develop protein-based products like adhesives and coatings. The paper deals with using wheat protein hydrolysate, namely SOLPRO 508 and casein reacted with triethyl phosphate (TEP) for the preparation of high-temperature resistance coatings.The Result of Matrix-Assisted Laser Desorption-Ionization – Time Of Flight (MALDI-ToF) and Attenuated Total Reflectance- Fourier Transform Mid-Infrared (ATR-FT MIR) spectroscopy confirmed that wheat protein and casein had the ability to react with triethyl phosphate. Moreover, the related coatings present outstanding adhesion and excellent solvent resistance.

Diffusion heat-resistant coatings for stainless and carbon steels

Diffusion heat-resistant coatings for stainless and carbon steels

Диффузионные жаростойкие покрытия для нержавеющей и углеродистой сталей

Диффузионные жаростойкие покрытия для нержавеющей и углеродистой сталей