Formation Of Composite Coatings Research Articles

BRIEF OVERVIEW OF METHODS FOR PRODUCING TiSiCN COATINGS AND THE METHOD OF REACTIVE PLASMA SPRAYING

Modern materials science sets itself the task of developing new materials with multifunctional coatings. Materials with such coatings are widely used in various fields of technology: construction and energy, microelectronics, aviation and others. The main reason for the emergence and development of technology for applying multifunctional protective coatings is the desire to increase the durability of parts and assemblies of various machine mechanisms. Wear-resistant hard coatings based on transition metal nitrides and carbonitrides are widely used to extend the life of forging and extrusion dies and high-speed machining tools. Over the past two decades, the widespread use of these coatings has stimulated and supported the development of new processes and materials in an attempt to further improve their properties. Among these coatings, the higher hardness, excellent oxidation resistance and high thermal stability of coatings such as TiSiN and TiSiCN make them the most promising candidates for demanding tribological applications. In addition, TiSiCN coating is a promising material used in marine environments due to its excellent anti-wear and corrosion resistance, as well as high hardness and low friction coefficient. These combinations of properties make TiSiCN coatings potential candidates for protective layers in the automotive and petroleum industries.The article briefly examines the possibilities of producing TiSiCN coatings using different deposition methods to control the properties of the resulting films and the features of the reactive plasma spraying method. The work describes the most common methods and technologies for producing carbonitride coatings currently used. The latest developments and current trends in the field of plasma spray coating technologies are reviewed, taking into account important innovations for industrial coatings. New conclusions that were obtained as a result of fundamental and applied research in physics or chemistry are based on them. The article provides a comparative review of the characteristics of obtaining wear-resistant TiSiCN coatings and the features of using reactive plasma spraying to obtain wear-resistant coatings. Based on an analysis of the literature, it can be argued that the further development of reactive plasma technology is associated with the development of a new resource-saving method for the formation of composite coatings with increased corrosion and tribological characteristics, which corresponds to the development trends of world science.

Formation of layered nanofibric materials and composite coatings

Using an electrospinning device, we determined the optimal conditions for producing nanofibers from a 10% solution of Co–AN. These conditions involved applying a 15[Formula: see text]kV voltage to the anode, which was connected to the syringe containing the solution, and maintaining a distance of 12–15[Formula: see text]cm from the needle tip to the collector screen (cathode). The filament diameter (d) ranged from 0.2 to 0.5[Formula: see text]mm. This setup allowed the formation of nanofibers under the cover. The electrolysis process was conducted for varying durations, ranging from 4 to 14[Formula: see text]h, while applying currents of 2[Formula: see text]mA, 4[Formula: see text]mA, and 8[Formula: see text]mA. At 4[Formula: see text]mA and 8[Formula: see text]mA, a substantial portion (approximately 65–70%) of the macroions in the solution reassembled on the electrode surfaces. These images clearly illustrate the restoration of macroions on the electrode surfaces, achieved through electron exchange processes. This phenomenon results in the combination of macroions and their neutralization, leading to the formation of a composite coating on the titanium, iron plate, and rods.

Low-energy electron beam deposition of coatings based on tannin and corn starch, their structure and properties

This paper, for the first time, presents the formation of composite coatings based on tannin, corn starch, and calcium dihydrophosphate by a low-energy electron beam in vacuum. Molecular structure, antiradical, antifungal and antibacterial properties of such coatings have been studied. Two-layer coatings (tannin + corn starch (1:1)) + Ca(H2PO4)2·H2O layer can be used for prolonged release of tannin into aqueous media. The bactericidal activity of the two-layer composite coating against S. aureus and S. viridans in most cases were found to be significantly higher than the bactericidal activity of the tannin coating. Two-layer composite coatings have pronounced fungicidal activity against C. albicans and can be used for treating oral lesions (mucositis).

Formation of Composite Coatings of Layered Double Hydroxide Particles and Hydroxide Gel by Electrophoretic Deposition on Mg Alloy and Corrosion Resistance

To improve the corrosion resistance of Mg alloys, composite coatings of layered double hydroxide intercalated with carbonate (LDH-CO3, hydrotalcite) particles and magnesium and aluminum hydroxide gel were formed on AZ31 Mg alloy by electrophoretic deposition (EPD) using the LDH-CO3 suspension with Mg(NO3)2 and Al(NO3)3 in total of 1.25–125 mmol/L. Wet-dry cyclic corrosion tests were performed for the coated specimens after ultrasonication. LDH-CO3 particle-rich layer and magnesium and aluminum hydroxide gel-rich layer almost alternately piled up to form a composite layer. The hydroxide gel adhered the particles together and to the substrate. At the bottom of the composite layer, flake-shape LDH-structured substance densely covered the substrate surface. The coverage and thickness of the composite layer increased from sub-micrometers to 30 µm with an increase of Mg and Al ion concentrations of the suspension. By ultrasonication, parts of the composite layer delaminated to expose the LDH-structured substance layer, while the coverage by the remaining composite layer increased with an increase of Mg and Al ion concentrations. The LDH-CO3 particles and hydroxide gel composite coatings prevented corrosion initiation even in the areas where the LDH-structured substance layer was exposed.

Formation of Composite Coatings during Detonation Spraying of Cr3C2

In the current practice of applying carbide-based coatings by thermal spraying, the starting material usually contains a metal binder. However, it is important to study the possibility of spraying binder-free carbides, since the metal components usually reduce the operating temperature and corrosion resistance of cermet coatings. In this work, a powder of chromium carbide, Cr3C2, was sprayed using a CCDS2000 detonation gun. Acetylene–oxygen mixtures C2H2 + kO2 with k varying from 0.8 to 3.0 were used as an energetic material. Due to chemical reactions between Cr3C2 and the detonation products, the coatings were of composite nature (multi-phase materials) with a composition depending on k. At k values in the range from 0.8 to 1.1, along with Cr3C2, the coatings contained chromium carbonitride Cr3N0.4C1.6. In the k range from 1.3 to 2.0, Cr7C3 and Cr were the main components of the coatings. As k was increased to 3.0, along with Cr7C3 and Cr, the CrO and Cr2O3 oxides formed in the coatings. The mechanical properties and wear resistance of the coatings were found to depend on their phase compositions. Coatings produced by detonation spraying of Cr3C2 powder may be useful for increasing the corrosion resistance of machine parts to mineral acids and high-temperature oxidation resistance.

Formation of composite coatings: morphology and composition studies

In this work, composite fluoropolymer-containing coatings were obtained on samples of AMg3 aluminium alloy, MA8 magnesium alloy, and VT1-0 commercially pure titanium treated by plasma electrolytic oxidation (PEO). Superdispersed polytetrafluoroethylene (SPTFE) and a solution of tetrafluoroethylene (TFE) telomers in acetone were applied onto preliminarily formed PEO layers by the spray-coating method. The obtained coatings contained a large amount of crystalline polytetrafluoroethylene embedded in the outer porous layer of the PEO coating and did not have visible defects, which indirectly indicates high protective properties.

Определение объемной доли первичных карбидов в микроструктуре композиционных покрытий с применением семантической сегментации

In the process of formation of composite coatings, partial dissolution of hardening particles (most often carbides) in the matrix is possible; therefore, in some cases, the material creation mode is chosen taking into account the volume fraction of primary carbides not dissolved during coating deposition. The methods currently widely used for calculating the volume fraction of carbides in the structure of composite coatings (manual point method and programs implementing classical computer vision methods) have limitations in terms of the possibility of automation. It is expected that performing semantic segmentation using convolutional neural networks will improve both the performance of the process and the accuracy of carbide detection. In the work, multiclass semantic segmentation was carried out including the classification on the image of pores and areas that are not a microstructure. The authors used two neural networks based on DeepLab-v3 trained with different loss functions (IoU Loss and Dice Loss). The initial data were images of various sizes from electron and optical microscopes, with spherical and angular carbides darker and lighter than the matrix, in some cases with pores and areas not related to the microstructure. The paper presents mask images consisting of four classes, created manually and by two trained neural networks. The study shows that the networks recognize pores, areas not related to the microstructure, and perfectly segment spherical carbides in images, regardless of their color relative to the matrix and the presence of pores in the structure. The authors compared the proportion of carbides in the microstructure of coatings determined by two neural networks and a manual point method.

Electrodeposition of Ni-zirconia or Ni-titania composite coatings from a methanesulfonic acid bath

The study addresses the patterns of formation of Ni-ZrO2 and Ni-TiO2 composite coatings from methanesulfonate and sulfate electrolytes at pH 3. It has been shown that the aggregative stability of the dispersed phase particles is better in the methanesulfonate electrolyte than in the sulfate electrolyte. As a result, at the same volume concentration of the non-metallic phase in both electrolytes, the concentration of particles is larger in the methanesulfonate electrolyte. This ensures the formation of composite coatings from methanesulfonate electrolyte with a content of non-metallic particles increased by 20–30 vol% compared to sulfate electrolyte. A mechanism for forming a composite coating has been proposed, which takes into account the different rates of the metal phase electrodeposition on the electrode surfaces that are free from the dispersed phase or conditionally occupied. A mathematical model of composite coating formation has been developed, which adequately describes the obtained experimental data. Incorporation of the non-metallic phase into the nickel matrix leads to a change in the coating structure and decrease in the sizes of metal grains. It has been found that the physicochemical properties of Ni-ZrO2 and Ni-TiO2 composite coatings depend on the content of non-metallic phase particles in them. It has been revealed that the microhardness of Ni-ZrO2 coatings obtained from methanesulfonate electrolyte is 10 % higher than the microhardness of coatings deposited from sulfate electrolyte, which is due to a higher content of the non-metallic phase. The photocatalytic activity of Ni-TiO2 composite coatings correlates with the content of the dispersed phase in them, which is due to the participation of TiO2 particle surfaces, accessible to irradiation, in the photocatalytic reaction. It has been found that an increased content of the dispersed phase in Ni-ZrO2 and Ni-TiO2 composite coatings obtained from methanesulfonate electrolyte leads to increased values of their microhardness and photocatalytic activity.

Smart composite antibacterial coatings with active corrosion protection of magnesium alloys

A new method of the formation of composite coatings with the function of active corrosion protection of magnesium alloys was developed using the plasma electrolytic oxidation (PEO) method. Susceptibility of PEO-layers to pitting formation was evaluated using localized electrochemical methods (SVET/SIET). The morphological features and electrochemical properties of composite coatings were studied using SEM/EDX, XRD, micro-Raman spectroscopy and EIS/PDP measurements, respectively. The effect of surface layers impregnation with corrosion inhibitor on their protective properties in a corrosive environment was established. Additional protection was achieved using controllable coating pore sealing with polymer. It was found that the polymer treatment of the PEO-layer does not reduce the inhibitor's efficiency. The formed protective composite inhibitor-and-polymer-containing layers decrease the corrosion current density of a magnesium alloy in a 3 wt.% NaCl solution to three orders of magnitude. This predetermines the prospect of new smart coatings formation that significantly expand the field of application of electrochemically active materials. The mechanism of smart composite coating corrosion degradation was established. The antibacterial activity of the inhibitor-containing coatings against S. aureus methicillin-resistant strain was proved using the in vitro model. These protective layers are promising for reducing the incidence of implant-associated infections.

Formation of composite coatings by ion-beam spraying of targets based on pyrogenic silica micro-powders containing copper compounds

In the introduction, the object of research is indicated – thin films obtained by ion-beam spraying of targets based on pyrogenic silica micro-powders containing copper compounds. The aim of the research is to study the behavior of copper ions during the formation of thin films by ion beam sputtering of a SiO2:CuO target in an Ar/O2 mixture of gases. The main part presents the results of a study of the structural and optical properties of thin films (~ 100 nm thick) formed by ion beam spraying of targets based on pyrogenic silica micro-powders containing copper compounds. The morphology of the film surface as a whole shows integral homogeneity and in fact does not depend on the composition of the gas medium, while there is some ‘‘granularity’’ of the coating surface, which is typical for spraying porous targets consisting of agglomerates or domain structures. The obtained frequency dependences of the dielectric constant of SiO2:CuO films showed a decrease in the dielectric constant in the range of 10 kHz – 1 MHz. It was found that when the SiO2:CuO film thickness is less than 100 nm, a thin-film capacitor is not always formed. Based on the analysis of the optical parameters of film accumulation depending on the sputtering medium, it was suggested that in an inert medium a large absorption of globular spheroidal CuO is formed in the film, and copper oxide can also be reduced to Cu+ and possibly to Cuº. It is indicated by the change in ε and tgδ, as well as an increase in the optical prohibited gap of SiO2:CuO thin films from 3.91 to 3.97 eV with an increase in the oxygen content in the Ar/O2 gas mixture. The resulting films can be used as active media in solar cells, sensors and other devices.

Formation of composite coatings by the method of supersonic plasma spraying of powders based on TiAl intermetallic with non-metallic refractory compounds SiC and Si<sub>3</sub>N<sub>4</sub>

The Paton Welding Journal, 2022, №06. International Scientific-Technical and Production Journal «The Paton Welding Journal» «The Paton Welding Journal» has been published monthly since 2000 in English, ISSN 0957-798X. «The Paton Welding Journal» is a cover-to-cover English translation of the «Avtomaticheskaya Svarka» (Automatic Welding) journal. The «Avtomaticheskaya Svarka» journal has been published monthly since 1948 in Russian, ISSN 005-111X.

Increase in properties of copper electrical contacts in formation of composite coatings based on Ni–C–Ag–N system

The article is concerned with analyzing the structure and properties of the Ni–C–Ag–N coating formed on copper by the complex method combining the electroexplosive spraying of coating, its irradiation by a pulsed electron beam and a subsequent nitriding in plasma of a gas discharge of low pressure. The structural constituents of coating's surface after the electroexplosive spraying as well as after the electron-beam processing and nitriding are studied. It is shown that a coating's thickness amounts to ≈90 μm. The wear resistance of a copper sample with the deposited coating exceeds that of the copper without the coating by ≈ 1.6 times. The friction coefficient of samples with the coating (μ = 0.5) is less than that of the copper without the coating (μ = 0.679) by ≈ 1.35 times. It is established that the hardness of the coating increases as the substrate is approached and reaches the maximum value of ≈1780 MPa (the hardness of substrate is 1300 MPa). By means of micro-X-ray-spectral analysis it is detected that the main chemical element of the coating is silver, but copper, nickel, carbon and nitrogen are present in a considerably smaller quantity. It is established by the methods of diffraction electron microscopy that the main phases of the coating are solid solutions.

Formation of Composite Coatings on Galvanized Steel from Organosilane Solutions Using Electrophoresis and Sol-Gel Technology.

New hybrid composite coatings (HCCs) on hot-dip galvanized steel (HDGS) were obtained using electrophoresis (cathodic polarization (CP)) and sol–gel technology. For this purpose, a technique for the preparation of a cationic precursor based on TiCl4 and aminopropyltriethoxysilane was developed. Electrophoresis of the charged particles of the precursor and organosilanes promotes the production of denser sol–gel coatings with improved adhesion. Using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS) methods, the formation mechanism and protective properties of HCC on galvanized steel were investigated.

МОДЕЛИРОВАНИЕ РАСПРОСТРАНЕНИЯ УПРУГИХ ВОЛН В ТРЕХКОМПОНЕНТНОЙ СРЕДЕ ПРИ ФОРМИРОВАНИИ КОМПОЗИТНОГО ПОКРЫТИЯ ПЛАЗМЕННЫМ НАПЫЛЕНИЕМ

In a three-component medium, when it is de-formed, acceleration waves propagate longitudi-nally on the wave surface. In this paper, the be-havior of acceleration waves and their influence on the quality of the propagation medium during the formation of composite coatings during plasma spraying were investigated. A flowchart has been compiled to create a software product that promotes theoretical studies of wave pro-cesses in a three-component environment.

Formation of composite coatings by carbide vibro-arc hardening

The processes of ignition and combustion of an electric arc during the formation of hardening composite coatings by the method of carbide vibro-arc hardening (CVAH) are investigated. It is established that an increase in the electric field intensity during CVAH can be achieved by minimizing the acceleration of the carbon electrode during its oscillations. The rational mode of the CVAH is determined. Keywords: composite coating, carbide vibro-arc hardening, arc ignition, combustion, carbon electrode, intensity, multicomponent paste.

Surface modification of carbon steel by electrodeposit composite coating for improving erosion-corrosion resistance: a review

This paper included an explanation of one of the methods of protection from corrosion, as it dealt with the use of electroplating technology by using solid ceramic particles embedded in chromium on carbon steel as a base material as an effective way to increase the service life of fluid-carrying tubes, considering that they are exposed to a joint effect of chemical and physical action. The formation of composite coatings on carbon steel and the factors affecting the success of these coatings in addition to a group of studies that dealt with these factors and their impact on increasing the resistance to conditions surrounding the metal represented by resistance to chemical corrosion in the presence of erosion (such as the concentration of solid particles in the paint solution, the temperature of the paint solution, the effect of The current density on the quality of the coatings and the effect of the thermal treatment on the coatings). The current density, the concentration of solid particles and the temperature have the greatest influence in determining the efficiency of the composite coatings.

Electrochemical formation of composite coatings by cobalt alloys in a pulsed mode

Electrodeposition of refractory metals and zirconium in composite alloys with cobalt allows to obtain coatings with a unique combination of physicochemical properties that are unachievable while using other methods of covering. By varying the composition of the electrolyte in galvanostatic mode it is impossible to obtain high-quality composite coatings with a high content of refractory components and current efficiency. As an alternative, it was suggested the use of pulsed electrolysis mode that allows to improve the producing of composite coatings. The selection of the ratio of pulse duration and pause allows avoiding the introduction of expensive additives and co-depositing metals in the alloy, which is not possible in the galvanostatic mode. Therefore, the purpose of the work was to determine the parameters for electrochemical deposition of cobalt coatings with refractory metals and zirconium from non-toxic electrolytes by pulsed electrolysis. The use of pulse mode at a ratio of the pulse duration 1×10-3-20×10-3 s and a pause duration of 2×10-3-20×10-3 s and an amplitude of the cathodic current density of 2-10 A/dm2 allows to obtain cobalt-based composite alloys with an increased content of zirconium, molybdenum and tungsten as comparing with stationary modes. Increasing the operating current densities causes the increase of the refractory metals content in composite alloys that contain molybdenum, and also decreases the grain size of the Сo-Mo-WхОy alloy surface layer. Based on the analysis of the experimental studies, the dependencies of current amplitude and pulse frequency on the current efficiency and composition of Сo-Mo-WхОy, Co-W-ZrO2 and Co-Mo-ZrO2 alloy coating were determined. The control of the composition of Сo-Mo-WхОy, Co-W-ZrO2 and Co-Mo-ZrO2 galvanic alloys in a quite wide range of alloying components concentrations is being achieved by varying the parameters of the pulse electrolysis, which allows adapting of the deposition technology to the needs of the modern market.

Features of electron beam deposition of polymer coatings with the prolonged release of the drug component.

The first part of the paper provides a comprehensive analysis of the features of electron beam formation of polymer coatings with the prolonged release of the drug compound using ciprofloxacin and clotrimazole as an example. The influence features of the low-energy electron beam on the molecular structure of medicinal chemical preparations have been established. The impossibility of producing the coatings based on medicinal compounds with a complex molecular structure (vancomycin, micafungin, etc.) by a low-energy electron beam has been justified. The second part of the paper introduces a fundamentally new vacuum method for the formation of the composite coatings based on antibiotics and antifungal drugs, accompanied by the prolonged release of the drug component. This method allows the formation of composite coatings based on medicinal compounds with a complex molecular structure. It is effective for modifying implants to prevent the risk of implant-associated infectious complications which are the result of the occurrence of mixed biofilms. The method can be used to form composite layers based on topical antitumor drugs for cancer control.

Influence of modifying coatings on dielectric permittivity of ceramic materials with composite coatings

The results of research of features of modification of aluminosilicate ceramics by suspension of fluoroplastic, aluminophosphate binder (AFS), non-aqueous compositions of polyurethane components, are presented. Samples of aluminosilicate ceramics for research were obtained by technological methods, including batch preparation operations, sample pressing, pre-annealing and sintering at a temperature of 1200–1350 °C. Polydisperse powders of aluminosilicates obtained by grinding waste of porcelain production (porcelain ware, GOST 28390-89); low-melting clay raw materials were selected as initial components. Modification of surface of aluminosilicate materials was carried out by impregnation of aqueous compositions based on a suspension of fluoroplastic and aluminophosphate binder (AFS), non-aqueous compositions of polyurethane components used in the preparation of polyurethane foam and 5 % solution of polyethylene hydrosiloxane in toluene with the formation of composite coatings on the surface of ceramic materials. It is shown that the application of organic film coatings (based on polyurethane, aluminophosphate binder and a suspension of fluoroplastic-4D, polyethylene hydrosiloxane) leads to formation of a multilayer dielectric material in which there are interface surfaces separating areas with different dielectric properties. In the presence of an external electric field, conditions are created for migration polarization between the crystalline phase of the substrate and the amorphous phase of the coating, due to the redistribution of free charges in the volume of the composite. Moreover, the chemical interaction of AFS with ceramics leads to the smoothing of the surface relief of the aluminosilicate base and the overgrowth of deep pores. Composite “aluminosilicate – AFS-fluoroplastic coating” differs from other materials, primarily in that aluminophosphate binder coating chemically reacts with the ceramic base. The impurity ions introduced during coating application, its composite structure, as well as the heterogeneity of the interface determine the pronounced frequency dependence ε and tgδ, as well as large dielectric losses of the composite in comparison with the original aluminosilicate material.

Electrodeposition of Transition Metal Composites on Mild Steel: Structural and Wear Behaviour

Wear characteristics of the transition metal composite (TMC) coated mild steel are investigated. TMC coatings were performed using electrodeposition technique on mild steel. Different concentrations of transition metals were subjected to prepare the TMC’s and studied. The structural and the micro structural studies of the composites coatings were studied through X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The elemental compositions of coated composites were evaluated using Energy dispersive X-ray diffraction (EDS) studies. Both the structural and micro structural characterizations confirmed the formation of composite coatings. Further, it is evident from the EDS analyses that TMC’s are coated with the desired concentrations. In order to understand the wear resistance of coated mild steel, the specimen were subjected to load on pin-on-disc type wear tester. The effects of concentration of composite and thickness of the coating on wear resistance are discussed. The coating results in improving the wear resistance and hardness of the specimen