Protective Properties Of Coatings Research Articles

Anti-corrosion resistance of coatings based on powder epoxy paints containing modifiers

The corrosion resistance of coatings (thickness 70 µm) based on epoxy powder paints modified with aliphatic amine or a mixture of anticorrosive pigments to the action of sodium chloride solution and salt spray has been studied. It is showed that with the increase of molecuar weight of initial epoxy oligomer and also at the incorporation of chemisorbing alifatic amine, containing polar groups, to the decrease in the permeability of the sodium chloride solution into the coating material is observed. It has been established that the observed changes in the properties of the coatings are due to the formation of a spatial structure of the polymer with different cross-link frequencies. It is shown that the introduction of a mixture of anti-corrosion pigments into the composition of paints provides a significant increase in the protective properties of coatings and a high preservation of the physical and mechanical properties of coatings in comparison with the base compositions. For 9000 hours of testing in a sodium chloride solution, the strength characteristics of the coatings decrease by about 10–12 % from the original ones. Based on the results of tests of coatings to the action of salt spray, the possibility of using the developed epoxy powder paints for operation in environments of a high atmospheric-corrosive category – C 5–1, including the application of coatings directly on a metal surface (Direct to metal) without multi-stage preparation of the metal surface for painting, is shown.

Vapor-phase deposition of polymer siloxane coatings on aluminum and magnesium alloys

Adsorption and polymerization of vinyltrimethoxysilane (VS) on the surface of aluminum AMG and magnesium alloy M20 in the presence of water vapor and ethylene glycol (EG) was investigated. It is shown that ethylene glycol is an effective polymerization promoter due to the crosslinking of hydroxyl and ethanol groups during polycondensation of VS and EG molecules on the surface of alloys. The main factors influencing the polymerization rate and protective properties of coatings are determined. Using XPS methods, it was found that ethylene glycol molecules interact with magnesium hydroxides to form magnesium glycolate polymolecules in the form of developed three-dimensional structures. The variation of the composition of the vapor-gas mixture makes it possible to obtain protective coatings with a different ratio of siloxane and poly-oxy magnesium structures. Azeotropic mixtures of vapor-gas deposition of coatings and optical methods for controlling the chemical composition of working solutions have been developed. Electrochemical and EIS studies of siloxane coatings on smooth and oxidized surfaces of alloys have been carried out. Impregnation of oxidized aluminum and magnesium alloys with organosilanes by vapor-gas gas deposition significantly increases their corrosion and mechanical resistance.

Development of graphene incorporated acrylic-epoxy composite hybrid anti-corrosion coatings for corrosion protection

Corrosion-induced damages have resulted in malfunctions as well as failures in metallic structures and led to economical loss. In addition, the wonder material, graphene, is widely applied in the corrosion protection coatings due to its excellent chemical stability, superior mechanical properties, and high corrosion resistance. Herein, the remarkable features of graphene-based nanofillers to improve the barrier performance of the acrylic-epoxy based polymer coatings are demonstrated. In different weight percentages, graphene nanoflakes were added to the blended polymer coatings and the hybrid coatings were characterized using Fourier-transform infrared spectroscopy (FTIR), Contact angle (CA), Field emission scanning electron microscopy (FESEM) and Electrochemical impedance spectroscopy (EIS) to investigate the chemical structure, surface roughness, surface morphology and coating dispersibility and corrosion protection properties, respectively. All the coatings were prepared using solution intercalation technique (sonication process) to overcome the nanoparticle agglomeration. Furthermore, the obtained results suggested that incorporation of 1 wt% graphene remarkable improved the protective properties of the polymer coatings due to the excellent dispersion and even distribution of the graphene nanoparticles. Moreover, an increment of the CA was displayed with a decreasing trend in the water absorption rate particularly for 0.5–3 wt% loading rates of graphene nanoparticles within the polymeric matrix. At higher graphene concentrations, the large agglomeration led in the overall reduction of the corrosion resistance. However, at different immersion time, the FESEM micrographs revealed that a strong anticorrosion barrier was provided by the graphene nanofillers over a period of 90 days of immersion. Overall, due to the fascinating properties of graphene, the inclusion of graphene-based nanofillers in the polymer matrix enhanced the barrier and protective properties of the coatings.

On the Limits of the EIS Low-Frequency Impedance Modulus as a Tool to Describe the Protection Properties of Organic Coatings Exposed to Accelerated Aging Tests

This study analyzes the limitations of the low-frequency EIS impedance modulus as a tool to describe the protective properties of organic coatings subjected to accelerated aging tests. Acrylic clear-coated steel and hot-dip galvanized steel were exposed to accelerated test methods such as the neutral salt spray chamber and the Prohesion test for up to 2000 and 3000 h, respectively. During exposure, the protective properties of the coatings were monitored by EIS and visual inspection. We observed a significant discrepancy between the measured impedance modulus in the low frequency range (|Z0.01Hz|), and the actual deterioration of the metal–paint interface. The degradation of the two painted substrates is independent of the accelerated test considered. The |Z0.01Hz| values do not represent the actual degradation state of the metal–polymer interface. The manuscript discusses the reasons for the lack of agreement between EIS and visual inspection. The limitations of using the low-frequency EIS impedance modulus to describe the protective properties of organic coatings are highlighted, and several cautions for interpreting the raw EIS data are suggested. The reliability of possible thresholds of |Z0.01Hz| (e.g., failure below 106 ohm∙cm2) to define the protective performance of the coating turned out to be misleading.

Influence of structure and content of hard blocks in polymer chain on properties of protective coatings

Новые технологии, Химическая промышленность, Химическая технология, Научные журналы, Защита от коррозии, Технология металлов, Свойства материалов, Технические журналы, Наука и технологии, Справочная литература, Научные разработки

Estimation of the Filled Two-Component Cold Curing Polymer System Performance as a Coating for Protecting Concrete Surfaces from the Aggressive Environment Exposure

A filled two-component polymer cold curingsystem (FTCPS) is discussed in the article. To assess its corrosion resistance and durability, the indexes of reagent resistance were determined in accordance with the sorption method. What is optimal, since this value depends on the parameters of mass transfer, the intensity of the reaction, the size of the product, the duration of exposure to aggressive media and other factors. As aggressive media were taken: water, 5% hydrochloric acid solution, 25% aqueous ammonia solution, 10% sodium hydroxide solution, saturated sodium chloride solution. The exposure time was 360 days. Reagent resistance evaluation of the developed FTCPScompositionswas carried out on the basis of guidelines for determining the anticorrosive properties of protective coatings of concrete and laboratory test methods. Changes in the mass of the samples and their reagent resistance as a result of exposure to chemical reagents simulating an aggressive environment during operation were evaluated. The change in the index of reagent resistance in laboratory conditions did not go beyond the value of 0.80, which makes it possible to ensure reliable protection and operation of polymer-coated products under conditions of exposure to these aggressive environments.

Barrier properties of “epoxy resin - amine hardener” film-forming systems

The article examines the physicomechanical and barrier properties of non-pigmented epoxy coatings formed from various film-forming systems based on epoxy resins and amine hardeners. The barrier properties of the coatings were evaluated by the nature of the frequency dependencies of the capacitance and resistance of the painted metal plates in contact with a 3 % aqueous solution of sodium chloride, and also by the magnitude of the displacement of the open circuit potential of the painted electrode compared to unpainted. It was experimentally established that a higher content of gel fraction is observed for coatings formed from low-viscosity film-forming compositions. It is shown that the physicomechanical and protective properties of epoxy coatings depend on the content of the functional groups in the epoxy resin and the nature of the amine hardener. It was found that to obtain coatings with better properties, it is preferable to use amine hardeners characterized by a low content of amine groups and a reduced proportion of secondary amino groups. A relationship was found between the protective properties of coatings and their water absorption. It is proposed to use the characteristics of water absorption of coatings as a simple method for assessing their barrier properties. The technological aspects of the use of the studied film-forming systems in the production of anticorrosive paints are considered. The advantages of using low viscosity epoxy film-forming systems without inert solvents are shown.

Premazi na bazi bazalta za zaštitu metalnih konstrukcija

The paper present the results of the synthesis of a new refractory coating based on basalt for the protection of metal construction under conditions of cavitation. Initial basalt samples obtained from the locality Vrelo - Kopaonik. The basalt based refractory filler was obtained by crushing and grinding selected samples of basalt rock. XRD, SEM and optical microscopy methods were used to characterize the obtained filler samples. The research defined the composition of basalt -based coating with epoxy resinbased binder, organic additives and organic solvent. The resistance properties of protective coatings applied to metal surface were investigated using the ultrasonic vibration method with a stationary sample according to the ASTM G 32 standard. To evaluate the resistance of the sample surface to the action of cavitation, the sample surface was examined before and during testing. The surface of the samples was monitored by scanning electron microscopy in order to analyze the morphology of surface damage. Computer image analysis according to the Image Pro Plus program was applied to assess the damage to the sample surface. The obtained test results showed high resistance of the coating layers to the effect of cavitation, with small mass losses, small damage to the coating surface and a cavitation rate of 0,1 mg/min.

The service life increasing of bushings by electro-acoustic spraying

The control of obtaining the predicted physico-mechanical properties of protective coatings of machine parts in a complex acoustic field by the method of electroacoustic spraying is carried out through the use of highly concentrated sources of electrical energy. The prediction of the physico-mechanical properties of the hardened surface of machine parts is made on the basis of the experiment planning methodology with non-orthogonal planning matrices. The adequacy of the obtained mathematical models was carried out using the criterion of adequacy of Fisher. Physical fundamentals of mass transfer of materials to a substrate in a complex acoustic field, realized through the transformation of longitudinal vibrations, to longitudinal-torsional, have been developed, while the amplitude of oscillation of the acoustic system is 5 to 15 micrometers. The use of longitudinal-torsional ultrasonic waveguides in this process and ultrafast cooling temperatures make it possible to form elements such as carbides, carbonitrides, and intermetallic compounds on the surface of a conductive material. The subsequent impact with a shift against the surface produced by the waveguide - electrode leads to irreversible microplastic deformations of the surface layer, which provide the specified parameters of surface quality and its physico-mechanical properties.

Modification of water-suspension epoxy varnish and paint materials by nanostructured magnesium oxide

The process of modifying aqueous powder suspension materials (APS) based on solid epoxy film-forming agents with highly dispersed powders of magnesium oxide was studied: production by ChemPur (n-MgO – primary size of particles is 36 nm), and magnesium oxide synthesized by a template method from the concentrated bischofite solution (MgOlab – primary size of particles is 102.8 nm). It was shown that presence of active functional surface OHgroups in both samples of magnesium oxide leads to the formation of secondary structures: aggregates and agglomerates. The nature of the influence of the size of aggregates of MgO particles and the conditions of dispersion on the properties of protective coatings is established. The nature of the influence of particle size and dispersion conditions on the properties of protective coatings is established. Optimal properties of coatings based on APS, sedimentation and aggregative stability of suspensions are implemented only under the condition of effective mechanical dispersion in a bead mill, when the most intensive destruction of large aggregates of n-MgO up to 50–60 nm occurs. The distribution of nanoparticle agglomerates in APS at the micro level (700–800 nm) using the MgO-lab does not lead to a significant change in the properties of APS and coatings based on them.It is shown that the introduction of n-MgO into APS allows reduces the curing temperature of the coatings from 110 to 90–100 °С. It is caused by the increase in the density of cross-linking of the spatial structure of polymer. The strength of modified coatings upon impact and tension increases by 2 times in comparison with the base composition, which does not contain nanomodifier, during curing of coatings at100 °C. In comparison with the known water-borne epoxy paints and varnishes, APS compositions are one-pack, they are more technological in use, have a long lifetime (up to 12 months in comparison with the viability of known two-pack epoxies, 1-8 hours). Materials can be used in industry for the protection of metal products, both as primers and as independent coatings.

Improvement of Technology of Formation of Coatings with Metal Effect by Modified Water-Dispersion Paints

The work is devoted to the study of the formation of protective and decorative coatings environmentally safe combined paint compositions. The considered work covers a range of issues related to colloidal-chemical modification of organo-soluble and water-dispersion lacquer compositions, development of their rational formulations and finishing modes, study of physical, mechanical and operational properties of protective coatings and ends with the calculation of the possible economic efficiency of the research results. In work environmentally safe water-dispersive paint and varnish compositions for transparent and opaque finishing by method of colloidal-chemical modification are developed. Optimal conditions for obtaining combined water-dispersion lacquer compositions of pigmented and non-pigmented and finishing modes are established. Modification of paint compositions with metal pigments allows to obtain a glazing coating, which significantly expands the color gamut of protective and decorative coatings.

Fabrication of a highly protective silane composite coating with limited water uptake utilizing functionalized carbon nano-tubes

Water uptake is an influential parameter on the protective properties of coatings. Carbon nano-tubes (CNTs) with different oxidation levels were used in this work to decrease water uptake of silane composite coating. The water uptake of the single-layer coatings was monitored using electrochemical impedance spectroscopy (EIS). In this assessment, power-law formula and effective medium theory (EMT) were exploited considering the parallel combination of the coating and electrolyte. EIS results showed that an increase in oxidation level of CNTs improved the protective functioning of the silane sol-gel coatings due to decrease in water uptake of the coatings.

Structure and protective properties of epoxy-polyester powder coatings containing curing accelerator

As a result of the study, the effect of curing accelerators (heterocyclic amine and zinc-containing accelerator) on the structure, physico-mechanical and protective properties of coatings based on powder epoxy-polyester compositions was established. The introduction of accelerators into the compositions affects the depth and speed of the curing process of film formers and provides the possibility to reduce the curing temperature. It has been established that the use of heterocyclic amine accelerator is more effective than a zinc-containing catalyst. For compositions containing heterocyclic amine, a decrease in gel time and an increase in the complex of physico-mechanical and protective characteristics of the coatings are observed, which were evaluated for the resistance of the coatings to the static action of a 3 % solution of sodium chloride. It is shown that changes in the protective properties of coatings, depending on the composition, correlate with the structural parameters of the polymer film and are due to the formation of the spatial structure of the polymer with different cross-link density. The use of mixtures of the investigated curing accelerators leads to an increase in the density of the polymer spatial network. This provides high protective properties of coatings to the action of aggressive electrolytes by reducing the permeability of corrosive media into the coating material. For 5000 hours of testing there are no pockets of corrosion under a film and no significant disruption of the continuity of the coatings (bubbles, peeling, wrinkling and cracking) in comparison with the basic compositions that do not contain accelerators.

Study of Synthesis and Evaluation of Heat-Resistant Coatings Based on Silicon–Boron Carbide–Zirconium Boride–Aluminum Oxide Composite

The effect of nanosized fibers of aluminum oxide on the properties of protective coatings based on the silicon–boron carbide–zirconium boride composite is investigated. The coatings applied on different substrates (graphite and ceramics) are compared and the effect of the thermal treatment conditions on the formed coatings is examined. It is demonstrated that the introduced additives do not weaken the coating’s thermal resistance and allow reducing the cost of the coating, darkening the color, and protecting it from erosion.

Effect of plasticizers on the qualitative indicators of film­forming coatings for the protection of chilled meat

The result of theoretical research into protection and prolonging the duration of meat and meat products storage has demonstrated that one of the promising directions is the application of protective coatings based on natural biopolymers. We used hydrocolloids as basic components of film-forming protective coatings. The study into mechanical and rheological properties of protective coatings was conducted; a comparative characteristic of these properties, which depend on the added plasticizer, is given. Film-forming coatings must possess high indicators of strength, elasticity, transparency, barrier properties, capability to sorb gases, water vapor. The film is to prevent undesirable effects for meat, to improve shelf life of the product without compromising quality indicators. Adding plasticizers to the composition of film-forming coatings will make it possible to control quality indicators of coatings. We have analyzed and theoretically substantiated the character and mechanisms of interaction between components of a film-forming coating and plasticizers. The viscosity of the film-forming coating without adding a plasticizer has the largest value compared to other solutions. The addition of plasticizers led to an increase in the elasticity of the film; we, however, observed a slight increase in strength. Film-forming coatings with the addition of a plasticizer had a higher yield limit and thus they were stronger than the integrated film-forming coatings without the addition of a plasticizer. On the other hand, the values of deformation of the film-forming coatings without the addition of a plasticizer were higher than those of the integrated film-forming coatings with the addition of a plasticizer, so they were more elastic. Studying the physical properties of the developed film-forming coatings based on hydrocolloids revealed that coatings with a plasticizer possess a larger vapor permeability. We have analyzed and theoretically substantiated the character and mechanisms of interaction between components of a film-forming coating and plasticizers. Based on results obtained in the course of experiments, it was established that the best mechanical, rheological, and physical indicators are demonstrated by the film-forming coating based on sodium alginate, carboxymethyl cellulose, and glycerin.

The Synthesis of Nitrogen-Containing Phenol Formaldehyde Oligomers Grafted with Vegetable Oils

The synthesis of nitrogen-containing alkyl(C8–C12)phenol formaldehyde oligomers grafted with vegetable oils was investigated with the aim of creating new materials with the properties of protective coatings. Soybean and linseed oils were used as the vegetable oils. The interaction between phenol formaldehyde oligomers and vegetable oils probably occurs through the functional groups formed as a result of oxidative processes at the carbon atoms in the a-position to double bonds. The probable structure was established using infrared and nuclear magnetic resonance spectroscopy, and the physicochemical properties of the synthesised products were studied.

The protective properties of coatings on a magnesium alloy formed by plasma electrolytic oxidation in silicate electrolytes

The protective properties of coatings on a magnesium alloy formed by plasma electrolytic oxidation in silicate electrolytes

IFHANAL-3 Inhibited Chromate-Free Conversion Coatings on V95T2 Aluminum Alloy

Alloys in the Al–Cu–Mg–Zn system are known to be characterized with high corrosion resistance in both atmospheric and aqueous media. It was earlier demonstrated that the alkaline chromate-free converting composite IFHANAL-3 enabled one to produce coatings with protective properties not inferior to those of conventional chromate coatings on a number of aluminum alloys, including that of grade V95 with different thermal treatment. The present work was devoted to studies of the effect of different complexing agents on the oxidation process and protective properties of coatings on V95T2 alloy. The studied modifying dopants decrease the concentrations of different oxides in the composition of conversion coatings, thus facilitating the adsorption of corrosion inhibitors and improvement of their protective properties. The decrease of the oxidation temperature in the solution of IFHANAL-3 modified with inhibitors of the azol type does not ly affect protective properties of the formed coatings.

Intensity of Exhaustion of the Properties of Protective Coatings during Heat Resistance Tests

The changes in the phase compositions of various protective coatings that occur during heat resistance tests are studied. The intensity of exhaustion of their protective properties as a function of the chemical and phase compositions of a coating is investigated. It is shown that the life of a coating can be increased due to the retardation of the diffusion processes occurring between the coating and the base alloy.

Protective properties of paint and lacquer coatings based on a fluorine-containing film-forming material

Paint and lacquer coatings (PLCs) are most commonly used when one needs to impart an aesthetic appeal to metal surfaces and protect them from the effects of the environment. Priming paint and lacquer compositions, which are dispersions of anticorrosion pigments in film-forming materials possessing a high adhesion to the surface that is being coated, are rather widespread among the variety of paint and lacquer corrosion- protection materials. The use of a fluorine-containing film-forming material to produce a PLC is rather promising. In this work, we have studied the protective properties of coatings that are based on epoxy varnish and a fluorine-containing polymer and filled with chromate and chromate-free anticorrosion pigments. The protective properties of PLCs have been evaluated by express tests in a salt spray chamber. The PLC structure has been analyzed by scanning-electron and atomic-force microscopy.