Formation Of Protective Coatings Research Articles

Eco-friendly corrosion inhibition of steel using phenolic compounds from Cynara syriaca

This study evaluates the corrosion inhibition performance of the n-butanol (n-BuOH) fraction derived from Cynara syriaca on mild steel in acidic environments. The n-BuOH fraction achieved up to 94 % inhibition at 500 ppm, as assessed through gravimetric analysis, potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS). Key phenolic compounds, including kaempferol, naringenin, myricetin, chlorogenic acid, and quercetin, were identified by UPLC-MS/MS. These compounds form stable flavonoid-metal complexes, as confirmed by UV–Vis spectroscopy. FT-IR and SEM-EDS analyses revealed the formation of protective coatings and interactions with the steel surface. Polarization curves indicate that the n-BuOH fraction acts as a mixed-type inhibitor, predominantly affecting the anodic reaction. The inhibition efficiency decreased from 93.89 % to 73.43 % with increasing temperatures. Thermodynamic analysis showed an increase in activation energy (Ea = 58.20 kJ/ mol) and a positive ΔH value of 56.17 kJ/mol, which can be attributed to the increased thickness of the double layer, enhancing the activation energy of the corrosion process. A Gibbs free energy (ΔG0ads) value of −25.48 kJ/mol confirms that the adsorption process is spontaneous and involves both physisorption and chemisorption. pKa analysis identified specific adsorption sites. This research underscores the potential of the n-BuOH fraction as a novel, eco-friendly corrosion inhibitor, offering valuable insights for sustainable corrosion control strategies.

Структура и свойства композиционного покрытия на основе высокоэнтропийного сплава, упрочненного частицами CrB

Introduction. Currently, a new class of materials, namely high-entropy alloys, is an active area of research. One of the areas of its application is the fabrication of protective coatings with high performance properties. The high-entropy alloy of CoCrFeNiMn composition is characterized by high ductility, which is retained both at elevated and cryogenic temperatures, as well as high thermal stability and, thus, can be considered as promising materials for protective coatings formation. At the same time, its disadvantages are low hardness and strength. It is known that the reinforcement of the CoCrFeNiMn high-entropy alloy with hardening particles is an effective way to improve the mechanical properties of coatings. It is assumed that the addition of hardening boride particles affects positively on the mechanical characteristics of the alloy. The aim of this work is to study the structural and phase states and wear resistance of coatings based on a CoCrFeNiMn high-entropy alloy reinforced with CrB particles. Coatings obtained by the method of non-vacuum electron-beam surfacing of powder mixtures with different mass ratios of CoCrNiMn metal powders to the CrB powder (100:0, 95:5, 90:10, 80:20, 70:30) are studied in this work. To investigate the structure and phase composition of the coatings, such methods as optical microscopy, scanning electron microscopy and X-ray diffraction analysis were applied. To study the elemental composition, energy-dispersive X-ray analysis was used. The mechanical properties were evaluated based on the microhardness measuring results. The wear resistance of the coatings was determined under conditions of dry sliding friction during reciprocating motion. Results and discussion. The addition of CrB powder to the surfacing mixture led to the formation of eutectic structures. When 5 wt. % CrB was added, a hypoeutectic structure is formed in the coating. An increase in the amount of CrB leads to the formation of coatings with a hypereutectic structure containing primary borides. The main phases found in the coatings are the fcc solid solution, and (Cr,Mn,Fe)2B, (Ni,Co,Mn)2B, CrB borides. All the studied coatings are characterized by an adhesive wear mechanism. The addition of 20 % and 30 % CrB to the surfacing mixture composition results in the wear resistance increase of the high-entropy alloy-based coatings by 3.6 and 6.1 times, respectively.

Formation of Protective Coatings Using an MAK-100 Plasma Spraying Installation

Formation of Protective Coatings Using an MAK-100 Plasma Spraying Installation

Overview of the plant-based synthesis of metal and metal oxide nanoparticles and their potential application in the formation of protective coatings

Overview of the plant-based synthesis of metal and metal oxide nanoparticles and their potential application in the formation of protective coatings

Іnfluence of finishing on the material performances

The complex of polyacrylic and polyurethane films physical and mechanical properties and the operational properties of leather decorated with them has been studied. The polyacrylate and polyurethane protective coatings formation is performed on the grain face of the semi-finished leather. 
 150–200 µm thick films are formed from the polymer solutions and aqueous dispersions. Acrylic films are obtained from a dispersion of methylbutylacrylate and a dispersion modified by acrylic lcarboxyethanolamine of kerosene-gas-oil fraction natural naphthenic acids. Polyurethane films are formed by the method of condensation structure formation in the presence of water vapor based on 4,4’-diphenylmethanediisocyanate, polyethylene glycol and polyester. Polyacrylurethane films are obtained from an aqueous dispersion of polyurethane and acrylate Lepton SPC.
 The coating is applied to the semi-finished leather by watering and spraying the polymer composition. The complex of physical-mechanical and sorption-diffusion properties of polymer films has been studied. It was found that the films obtained from the polyacrylurethane composition outperform polyurethane and polyacrylic by 1.9 and 6.7 times, respectively. Modification of the polyurethane composition with a polyacrylic polymer makes it possible to obtain films with higher sorption-diffusion properties.
 Polyurethane coated leather is superior to polyacrylic in the complex of physical and mechanical parameters, in particular in terms of adhesive strength in 3.4-4.4 times, and polyacrylurethane coated leather - in 5 times. Such leather has the highest sorbino-diffusion capacity, which is 1.4 times higher in vapor permeability compared to skins with polyacrylic coating. The acrylurethane polymer-based composition is promising formation of eco-coatings based on them in the technology of manufacturing leather materials. The studied polymeric film formers can be used for the formation of various kind protective coatings on a wide range of semi-finished leather products.

Physicochemical studies of composite coatings during accelerated tests for atmospheric corrosion

In the present paper, the formation of protective coatings on the MA8 magnesium alloy by plasma electrolytic oxidation (PEO) with subsequent treatment of fluoropolymer is considered. The morphology of coatings after accelerated climatic tests was investigated and the elemental composition of coatings was studied after tests in a salt spray chamber (SSC). The analysis of the obtained results demonstrated a higher corrosion resistance of the fluoropolymer-containing layers in comparison with the base PEO coating.

Redox-dependent surface passivation reduces phytolith solubility

Phytoliths are an important silicon (Si) source for plants due to their high solubility, yet some phytoliths are stable for centuries and used in paleosciences to reconstruct past vegetation. Here, we show that this discrepancy can be resolved by considering interactions of phytoliths with soil solution constituents. We tested the hypothesis that recurring alternating redox conditions reduce the solubility of phytoliths due to the formation of protective coatings. Phytoliths from rice plants were repeatedly exposed to solutions from a typical paddy soil under either exclusively oxic conditions or alternately anoxic−oxic conditions. Changes in solution chemistry and surface properties (chemical composition, ζ potential, surface area and porosity) of exposed phytoliths were linked to phytolith dissolution kinetics over 30 days (in 0.01 M CaCl2 at pH 7). We found that phytoliths exposed to alternating redox conditions accumulated iron and carbon at their surfaces, with changes in other properties being little. Dissolution rates decreased after exposure to soil solution regardless of redox conditions, but more pronounced under alternating redox conditions. After six exposure steps, the Si dissolution rate for the alternating redox treatment decreased by factor of 3.2 (oxic treatment: 2.1), with the Si release rate being negatively correlated with total iron contents. We conclude that alternating redox conditions can cause increased phytolith stability due to surface passivation and, in turn, reduced Si availability to plants.

ПЕРСПЕКТИВИ РОЗВИТКУ ТЕХНОЛОГІЙ ТА ОБЛАДНАННЯ САМОРОЗПОВСЮДЖУВАЛЬНОГО ВИСОКОТЕМПЕРАТУРНОГО СИНТЕЗУ

Purpose. The work is aimed at building an algorithm and coating processing on structural steel, its detailed control at each stage and analysis in obtained material physical and technical characteristics. Methodology. The research of the mechanism of obtaining coatings, as well as operational tests of the obtained samples, computer simulation and spectral analysis are offered. Findings. The kinetics of protective coatings formation on steel 50 has been studied. Вased on the obtained data, the conditions for obtaining the greatest coating thickness are predicted. The rational technology of obtaining alloyed chromium-alloy protective coatings on structural materials has been developed, which allows to use the spent charge as: ballast filler for SHS-charges, abrasive material for grinding, powder material for spraying. The study of the microstructure, phase composition of alloyed chromium-alloy protective coatings, their performance characteristics was carried out on the basis of the obtained material. The analysis of surfactant solutions (surfactants) use efficiency as lubricants in the course of SHS processes and development the forecast estimations system for efficiency use the surfactant solutions as lubricants in the course of SHS processes is carried out. Originality. On the basis of the conducted researches and the received results new alloyed chromium-alloyed protective coatings and compositions of powder charges for self-propagating high-temperature synthesis are developed. Practical value. The implementation of the developed recommendations will increase the service life by 2,7–3,2 times by increasing the wear resistance by 1,9–2,1 times. Сonclusions. Boron and titanium alloy chromium-analytical protective coating is obtained on the parts in order to increase their wear resistance. Low cost of a covering in comparison with known methods of reception of coverings in isothermal conditions is provided by insignificant prime cost of components of SHS-charge, and also increase in service life of technological equipment.

The Protection of Building Materials of Historical Monuments with Nanoparticle Suspensions

Marble and limestone have been extensively used as building materials in historical monuments. Environmental, physical, chemical and biological factors contribute to stone deterioration. The rehabilitation of stone damage and the delay of further deterioration is of utmost importance. Inorganic nanoparticles having chemical and crystallographic affinity with building materials is very important for the formation of protective coatings or overlayers. In the present work, we have tested the possibility of treating calcitic materials with suspensions of amorphous calcium carbonate (am-CaCO3, ACC) and amorphous silica (AmSiO2). Pentelic marble (PM) was selected as the test material to validate the efficiency of the nanoparticle suspension treatment towards dissolution in undersaturated solutions and slightly acidic pH (6.50). Suspensions of ACC and AnSiO2 nanoparticles were prepared by spontaneous precipitation from supersaturated solutions and by tetraethyl orthosilicate (TEOS) hydrolysis, respectively. The suspensions were quite stable (nine days for ACC and months for AmSiO2). ACC and Am SiO2 particles were deposited on the surface of powdered PM. The rates of dissolution of PM were measured in solutions undersaturated with respect to calcite at a constant pH of 6.50. For specimens treated with ACC and AmSiO2 suspensions, the measured dissolution rates were significantly lower. The extent of the rate of dissolution reduction was higher for AmSiO2 particles on PM. Moreover, application of the nanoparticles on the substrate during their precipitation was most efficient method.

Protective Coatings Formation using Thermal and Thermochemical Treatment to Create “Unidirectional” Gradient Structures in VT6 Titanium Alloy

Protective Coatings Formation using Thermal and Thermochemical Treatment to Create “Unidirectional” Gradient Structures in VT6 Titanium Alloy

/ EXPERIMENTAL STUDY OF THE INFLUENCE OF DIE PARAMETERS ON COATING THICKNESS

It is presented design of the drawing unit, developed by the authors, for the formation of protective coatings, and the results of experimental studies of the influence of drawing tool parameters are given in order to develop practical recommendations for creating optimal coating application conditions.      

Plasma electrolytic oxidation technology for producing protective coatings of aluminum alloys

Today, the technology of hardening the surface layers of parts and the creation of protective coatings on the surface with high physical, mechanical and chemical properties is particularly effective. The article reviews the most promising innovative technologies for surface hardening of aluminum alloys – plasma electrolytic oxidation (PEO). Possible conditions and mechanisms for the formation of protective coatings on the surface of aluminum alloys are considered. The influence of the main parameters of PEO processing (electrical parameters, composition and concentration of electrolyte, the influence of alloying elements) on the structure and properties of oxide-ceramic coatings has been studied. The qualitative characteristics of the surface layer of samples and finished products made of aluminum alloys have shown the effectiveness of the PEO technology, which makes it possible to obtain ceramic coatings with high hardness, strength, increased wear and corrosion resistance. Possible areas of application of high-performance technologies for the deposition of protective PEO coatings on the surface of products made of aluminum alloys are proposed.

Method of operational life’s increasing of transport’s parts due to usage of coatings based on epoxy matrix modified by maleinic anhydride with improved thermal physical properties

The use of a new method of operational life increase of the transport means parts due to the introduction of polymer-based modified materials has been substantiated in the paper under discussion. It is shown that the use of matrices based on epoxy diane oligomers is quite promising direction in protective coatings formation. Some active additives have been applied to improve the properties of epoxy matrices on preliminary stage of their formation. The use of maleinic anhydride modifier containing active to the interphase interaction functional groups is promising as well. Epoxy diane oligomer has been used as the main component for the matrix in the composite formation. The hardener polyethelenepolyamine has been used to link the epoxy compositions enabling to harden the materials at room temperature. The choice of maleinic anhydride as a modifier to improve thermal-physical properties of the developed materials has been substantiated. It has been found that to form a composite material or a protective coating with improved thermal-physical properties it is necessary to apply maleinic anhydride as a modifier in epoxy matrix in the following ratio: q = 0,5 pts.wt. per q = 100 pts.wt. of epoxy oligomer ЕД-20. In this case the material has been formed where, comparing with nonmodified matrix, the indices of glass transition temperature are being increased from Тс = 327 К tо Тс = 335 К, heat resistance (by Martenson) from Т = 341 К to Т = 362 К, and thermal coefficient of linear expansion in the range of temperatures ∆Т = 303…423 К is being decreased from α = 9,9 ×10-5 К-1 to α = 4,4 ×10-5 К-1. It has been proved that the maleinic anhydride content in the matrix with its small fraction (q = 0,5 pts.wt.) has activated the processes of interphase interaction in epoxy CM structure formation, resulted in the increase of number of both physical and chemical bonds per polymer volume unit. This process will involve the increase of gel fraction degree in CM, and, correspondingly, both the cohesion and thermal-physical properties of modified CM have been improved. The developed material under discussion could be efficiently used as a matrix in formation of protective coatings which are to be operated under high temperatures conditions and dynamic or static loadings.

Modeling of the protective coatings formation mechanism by micro-arc oxidation

An electrophysical model of the micro-arc oxidation process, which allows, on the basis of the equivalent electrical circuit and fundamental laws of physics and chemistry, to describe the formation mechanism of protective coatings by the micro-arc oxidation method taking into account the large number of physical effects inherent in this process is proposed. The proposed model can be used to increase the controllability of micro-arc oxidation technology.

MODELING PRODUCTION OF CORROSION RESISTANT DIFFUSION LAYERS UNDER NON-STATIONARY TEMPERATURE CONDITIONS

The paper discusses methods for obtaining alloyed chromium-alloyed coatings and the search for optimal powder mixtures that allow the formation of protective coatings on CCCM under non-stationary temperature conditions. Refractory compounds, primarily carbides, borides, nitrides and silicides, as well as alloys based on them, can be promising materials for applying protective coatings. In addition to protection against oxidation, coatings made of refractory compounds have high hardness and wear resistance. The implementation of the application of protective coatings on high-carbon materials is difficult for a number of reasons. This concerns the low wettability of the carbon surface by refractory metals, low adhesion of the coating to the substrate, which largely depends on the thermophysical properties of the coating, and also the choice of coating components depending on the operating conditions of the finished product. Under non-stationary temperature conditions, it is possible to obtain coatings of various chemical compositions by varying the amount and content of alloying additives. The gas-transport method of applying coatings using UTC makes it possible to obtain CCCM with enhanced physical and mechanical properties, without requiring high energy costs and time.

Correlation between the Properties of PEO-Layer and Coating Formation Current Density

Presented paper considers the formation of protective coatings on MA8 magnesium alloy by plasma-electrolytic oxidation (PEO). The influence of current densities formation on the structure, corrosion properties of PEO-coatings was studied. Electrochemical and scanning electron microscopy of the surface and cross-section of the samples were carried out. The effect of changing the formation current density on the functional parameters of coatings, such as corrosion resistance, thickness and porosity was investigated.

Incorporation of TiO<sub>2</sub>(B) Nanoparticles into PEO Coatings on MA8 Magnesium Alloy

The way of protective coatings formation on MA8 magnesium alloy by plasma electrolytic oxidation (PEO) in the electrolyte containing TiO2(B) nanoparticles has been developed. It is shown that the coatings, which contain nanoparticles, have a significant advantage in microhardenss and adhesive strength in comparison with the surface layers obtained without their use.

Вплив процесів, що відбуваються в рухомих спряженнях деталей транспортних машин під дією компонентів геомодифікатора, на ефективність триботехнологій припрацювання і відновлення

It is shown that the effectiveness of the implementation of tribotechnologies for running-in and restoration of systems and assemblies of transport machines depends on the preparation of the working environment in which the running-in of tribocouplings of parts takes place. When using a geomodifier to add to engine and transmission oil, it is important to refine the particles of its components and obtain special properties of their surfaces. The properties of the main components of the KGMT-1 geomodifier: SiO2, MgO, Al2O3, Fe2O3 are considered. Their activation during grinding and feeding into the friction zone is substantiated. The change in the size of the particles of the components of the geomodifier on the duration of the test under various operating conditions and within the limits of the strength intervals was investigated. The course of various physical processes according to nonequilibrium thermodynamics and the realization of states and processes of self-organization are considered. It was found that, depending on the degree of fragmentation, the particles of the components exhibit different activity, and therefore, different conditions for the formation of protective coatings on the working surfaces of parts and tribomechanical and tribophysical effects on particles are realized. It is shown that the latter manifests itself during the formation of defects, specific surface area, and duration of mechanical activation. It was revealed that for the materials of the KGMT-1 geomodifier components with strongly homeopolar bonds, such as SiO2, SiC, and the aluminosilicate mineral kaolinite, an amorphization process is observed. The influence of the α-Si-k-Si phase transformation in the materials of the KGMT-1 additive on the efficiency of the implementation of tribotechnologies has been determined. It is shown how physical processes in a composite oil cause tribochemical reactions and formation of coatings on the working surfaces of interfaces of parts of systems and aggregates of transport machines.

MODELING OF DIFFUSION COATINGS STRUCTURE WITH VANADIUM AND TUNGSTEN IN COMPOSITION-FILLING ENVIRONMENTS

The process of modeling the production of vanadium and tungsten coatings is an effective method of increasing the reliability and durability of machine parts, tools by creating protective layers on the surface of the workpiece, which have a unique set of physico-chemical properties.One of the most effective methods of developing protective layers having high mechanical, physical and chemical characteristics is the diffusion saturation of the surface of the layers using composite powder materials.The formation of protective coatings in composite saturation media occurs under non-stationary temperature conditions. The method of diffusion saturation of the solid phase surface in the active gas medium is based on the analysis of the requirements for the diffusion layer and the method of metal saturation is selected. The rates of chemical processes are determined by kinetic regularities that depend on both temperature and diffusion factors. This method provides high surface quality, is the simplest and most used in laboratory practice, reproduces well in production conditions, and does not require special sophisticated equipment to implement it.

Calculation of Physicochemical Conditions of the Formation of Protective Coatings Based on Carbides and Nitrides of Chromium

Calculation of Physicochemical Conditions of the Formation of Protective Coatings Based on Carbides and Nitrides of Chromium