Composite Electrochemical Coatings Research Articles

Improving reliability and service life of industrial products via composite electrochemical coatings

The paper considers a method for obtaining hard, wear-resistant composite electrochemical tungsten carbide-cobalt (WC-Co) coatings with high adhesive strength. Such coatings are used to enhance surface hardness and wear resistance of parts and tooling. It is challenging to obtain hard, wear-resistant coatings on the surface of industrial parts and tooling. It is proposed to use an eco-friendly cobalt electrolyte with tungsten carbide additive for the electrodeposition of composite electrochemical coatings. The electrodeposition technique provides high output and quality of the applied coating with the ability to control its thickness.

Electrodeposition and Properties of Composite Ni Coatings Modified with Multilayer Graphene Oxide.

Within the framework of this study, Ni-based composite electrochemical coatings (CECs) modified with multilayer graphene oxide (GO) processed using microwave radiation have been deposited. The process of these coatings' electrodeposition in the potentiodynamic mode has been studied. The structure of Ni-GO and Ni-GO (MW) CECs has been studied using X-ray phase analysis (XPA) and scanning electron microscopy (SEM).It has been shown that the addition of GO into a nickel deposit contributes to the formation of uniform fine-grained coatings. As a result, the microhardness of the Ni-GO (MW) CECs increases by 1.40 times compared to Ni without GO. The corrosion-electrochemical behavior of nickel CECs in 0.5 M H2SO4 solution was researched. It was established that the corrosion rate of the nickel-GO (MW) CEC in 3.5% NaCl decreases by about 1.70 times in contrast to unmodified nickel coatings. This effect is due to the absence of agglomeration of the graphene oxide in the volume of the nickel matrix and the impermeability of GO particles to the corrosive environment.

Structural Features of Ni–SiC Composite Electrochemical Coatings with Submicrometer Grain Size, Prepared Using Vibrational Mixing

Structural Features of Ni–SiC Composite Electrochemical Coatings with Submicrometer Grain Size, Prepared Using Vibrational Mixing

Study of Electrodeposition and Properties of Composite Nickel Coatings Modified with Ti3C2TX MXene

In this work we have synthesized Ti3C2TX MXene powder and studied its structure. Composite electrochemical coatings (CECs) of Ni-Ti3C2TX MXene were obtained from a sulfate– chloride bath in the galvanostatic regime. The microstructure of CEC was researched using X-ray phase analysis and scanning electron microscopy methods. It has been established that a Ni–Ti3C2TX MXene CEC microhardness rises by about 1.80 times compared with electrolytic Ni without a dispersed phase. For corrosion research, different corrosive media is applied. The corrosion–electrochemical behavior of Ni–Ti3C2TX MXene CECs by the chronovoltamperometry method in 0.5 M H2SO4 solution has been investigated. Trials in 3.5% NaCl have shown that Ti3C2TX MXene inclusion into the matrix of the electrochemical Ni results in a decrease in the corrosion rate by 1.60–1.75 times. These effects are due to the addition of Ti3C2TX MXene into the nickel matrix and the formation of CECs with a strengthening fine-grained structure.

Properties and Structure Electrodeposition Alloys and Composite Electrochemical Coatings of Nickel-Based

The physicomechanical properties and morphology of composite electrochemical coatings (CEC) nickel-cobalt-nanodiamond from a chloride electrolyte-colloid of optimal composition have been investigated. For this CEC, microhardness (21-25 GPa) and internal compressive stresses (150-210 GPa) were determined. The study of wear and the Corrodcoot-test of the CEC showed a higher wear resistance (1,5 times) and the protective ability (2-3 times) of the CEC in comparison with chrome coatings. Studies of the CEC morphology and the nickel-cobalt alloy showed that the roughness of the resulting deposits, in comparison with nickel coatings, is 10 times less, and the fractal dimension of the coating surface is of the greatest importance. The cubic type of the nickel-cobalt-nanodiamond CEC lattice is established. The leveling effect on the structure of galvanic deposits of nanodiamond introduced from outside, as well as of microheterogeneous nickel and cobalt compounds formed in the electrolyte-colloid, has been determined.

Biocidal and Corrosion Properties of Composite Electrochemical Coatings Based on Tin–Nickel Alloy

Biocidal and Corrosion Properties of Composite Electrochemical Coatings Based on Tin–Nickel Alloy

Pulsed Electrodeposition and Properties of Nickel-Based Composite Coatings Modified with Graphene Oxide

Composite electrochemical coatings (CECs) on the basis of nickel modified with multilayer graphene oxide (GO) were deposited from a sulfate–chloride electrolyte in pulsed electrolysis mode. The microstructure of these CECs was studied by X-ray phase analysis and scanning electron microscopy. It was found that the microhardness of nickel–GO CECs increases by approximately 1.40 times compared to pure nickel. The corrosion–electrochemical behavior of nickel–GO composite coatings in 0.5 M H2SO4 was studied. Based on tests in 3.5% NaCl, it was found that the addition of graphene oxide particles into the matrix of nickel electrodeposits, increases their corrosion resistance by 1.40–1.50 times. This can be explained by the uniformity of the distribution of GO in the nickel matrix, which contributes to the reduction in grain size, as well as the impermeability and stability of graphene oxide.

Formation and Physicochemical Properties of Composite Electrochemical Coatings of Tin–Nickel Alloy with Silicon Dioxide Incapsulated by Nanosized Titanium Dioxide

Formation and Physicochemical Properties of Composite Electrochemical Coatings of Tin–Nickel Alloy with Silicon Dioxide Incapsulated by Nanosized Titanium Dioxide

Influence of heat treatment on tribocorrosion properties of Ni-B composite coatings

Various surface protection technologies, in particular, electrochemical, are used to increase the wear and corrosion resistance of steels and alloys. Composite electrochemical coatings (CEC) technology is more promising than "pure" galvanic coatings. Application of CEC increases the wear, corrosion and fatigue failure resistance of metals. Nickel often is chosen as a CEC matrix because it easily forms uniformly filled defect-free composite structures with many particles of the dispersed phase (DP).
 Physical and mechanical properties of metal coatings determine practical application of such composition. The characteristics of nickel-based CEC are: high hardness and strength, significant corrosion resistance in atmospheric environment, as well as in alkali and mild acidy environments. An effective composition coating with tribological designation can be CEC Ni-B, received in the process of electrolysis from suspension of amorphous boron in nickel electrolyte. A new composite structure of matrix filled type Ni-Ni3B is formed after heat treatment. Composition and structure of coating is determined by regimes of diffusion annealing. Ni-B coatings increase wear resistance of steel in chlorine-based environments. The influence of low-temperature thermal treatment of Ni-B CEC on steel 09Mn2Si on their tribocorrosion behavior is investigated. It is shown that the structural factor has a decisive influence on the efficiency of such friction pairs. The CEC has the least wear and the most positive compromise electrode potential after vacuum annealing at 450°C, when the initial stage of solid-phase interaction of coating components with the formation of Ni-Ni3B occurs.

Functional composite electrochemical coating Ni-Co-Al2O3 -an alternative to chromium plating

The physico-mechanical properties of composite electrochemical coatings (CEC) nickel-cobalt-aluminum oxide were investigated depending on the electrolyte parameters and electrolysis conditions. The previously developed low-concentration chloride electrolyte for nickel plating was used as an electrolyte to replace environmentally hazardous chromium plating electrolytes containing hexavalent chromium, which is prohibited by the laws of many countries. The wear resistance of the obtained CEC was determined on a three-ball friction machine. This made it possible to establish that the wear resistance of the CEC exceeds the wear of chrome coatings in dry friction mode by 2-2,5 times and is comparable to chromium in the friction mode with lubrication. In the dry friction mode, the higher wear resistance of the nickel-cobalt-alumina coating is explained only by the higher hardness of the latter. Probably, upon destruction of the coating, the particles of the alloying addition act as a solid lubricant, which causes an increase in the resistance of the CEC during wear. The microhardness of the CEC was determined using a PMT-3 microhardness tester and amounted to 6-25 GPa. The microhardness value was influenced by the concentration and properties of the dispersed phase, as well as the electrolysis conditions - the temperature and pH of the electrolyte, and the cathode current density. “Corrodcote” test was used in the study of corrosion. According to its data, the corrosion resistance of CEC is 2-3 times higher than the corrosion resistance of chromium deposits. The results obtained make it possible to recommend the developed functional CEC of nickel-cobalt-alumina instead of chromium coatings as corrosion- and wear-resistant.

Сomposition, structure and functional properties of silver-tungsten composition electrochemistry coatings formed with the help of ultrasound

Influence of electrolyte composition and deposition parameters on the composition, structure, physicalmechanical and functional properties of composite silver-tungsten coatings was studied. It was shown that addition of sodium tungstate in electrolyte and application of ultrasound at the electroplating leads to formation of silver layers that contains tungsten oxides and demonstrates lower crystalline nucleus. Application of ultrasound vibration at the electrochemical deposition increases ability for plating process control and allows to optimize electrophysical and functional properties of composite electrochemical coatings, to make dense fine crystalline thin layers. Obtained layers demonstrate increased microhardness (by 10–50 %), wear resistance (1,5–2 times), corrosion resistance and improved contact electrical resistance. It is shown that application of ultrasound effect to electrodeposition allows increased level of permissible current density and provides.

Electrodeposition and Corrosion Properties of Nickel-Graphene Oxide Composite Coatings.

Nickel-based composite electrochemical coatings (CEC) modified with multilayer graphene oxide (GO) were obtained from a sulfate-chloride electrolyte in the reverse electrolysis mode. The microstructure of these CECs was investigated by X-ray phase analysis and scanning electron microscopy. The corrosion-electrochemical behavior of nickel–GO composite coatings in a 0.5 M solution of H2SO4was studied. Tests in a 3.5% NaCl solution showed that the inclusion of GO particles into the composition of electrolytic nickel deposits makes their corrosion rate 1.40–1.50 times less.

Influence of sulfate and nitrate ions on kinetics of dissolution of chromium (III) α-CrOOH hydroxide

Chrome is part of many alloyed steels and wear-resistant composite electrochemical coatings. Chromium films are used as firming coatings of metal products and cutting tools in electronic technology. Chromium alloys are used in industry for the manufacture of parts of machines and mechanisms intended for operation in extreme conditions for the formation of durable coatings on metal and other surfaces. Therefore, the question of optimizing the technologies of etching, leaching and enrichment of chromium-containing ores. The paper discusses the kinetic features of the dissolution of chromium hydroxide (III) and proposes the optimal mechanism for the dissolution of chromium hydroxide (III) α-CrOOH in the presence of various ions (sulfate and nitrate) in acidic environments. The influence of various mineral acid ions on the kinetics of dissolution of chromium hydroxide (III) α-CrOOH in acidic environments is considered. The mechanism of dissolution of chromium hydroxide (III) α-CrOOH is proposed from the standpoint of various model representations. The most important direction of research in metallurgy is the selection of effective reagents and determining the main kinetic parameters of dissolution processes. An analysis of data on the influence of the nature of mineral acids on the rate of dissolution of chromium hydroxide (III) α-CrOOH is carried out. To calculate the empirical values of kinetic parameters, the methods of regression analysis were used. In order to select the technological regimes of the selective extraction of valuable metals from raw materials, the following parameters are considered (with acid and anions, T, pH).

Electrodeposition of Graphene Oxide Modified Composite Coatings Based on Nickel-Chromium Alloy

Composite electrochemical coatings (CECs) based on nickel-chromium alloy and modified with multilayer graphene oxide (GO) were obtained. The electrodeposition process of these coatings was studied in the potentiodynamic mode. The structure and the composition of nickel–chromium–GO CECs were studied by scanning electron microscopy and laser microspectral analysis. Nickel–chromium–GO CECs are dense and uniform. The carbon content in them increases when moving from the substrate to the surface. It was established that the addition of GO particles into the composition of electrolytic coatings with a nickel-chromium alloy results in the increase in their microhardness from 4423–5480 MPa to 6120–7320 MPa depending on the cathodic current density.

Electrodeposition kinetics and surface morphology of Ni-B-UDD composite coating

The article presents the results of kinetic investigates of electrodeposition of a composite electrochemical coating based on a nickel-boron alloy. Current efficiency, polarization potentiodynamic researches had shown the joint participation in the electrodeposition process of finely dispersed compounds of nickel hydroxides, poorly soluble nickel and boron compounds present in the electrolyte or formed during electrolysis, and ultradispersed diamond introduced into the electrolyte. Comparison of 2D and 3D scans of the surfaces of the formed coatings confirmed the leveling effect of additives, as well as sparingly soluble nickel and boron compounds on the structure of coatings. The proposed composite electrochemical coatings can be used instead of chrome coatings when restoring parts and units of agricultural machinery.

Electrochemical Deposition of Zinc-Based Composite Coatings Modified with Carbon Nanotubes from Alkaline Electrolyte

Composite electrochemical coatings (CECs) based on zinc, modified with carbon nanotubes (CNTs) from an alkaline electrolyte in a pulsed electrolysis mode have been obtained. The microstructure and tribological properties of these CECs are investigated. It was found that the introduction of the dispersed CNT phase into the alkaline galvanizing electrolyte reduces the sliding friction coefficient of the forming coatings by a factor of 1.30–1.45. The corrosion–electrochemical behavior of zinc–CNT CECs in 0.5 M solution of H2SO4 has been described.

The role of dispersed phase in the formation of Ni – CEC

Composite electrochemical coatings make it possible to successfully solve many practical problems of surface hardening of structural parts, tooling and restoration of their wear parts. One of the factors influencing the structure and properties of composite coatings is characteristics of the dispersed phase (nature, concentration, dispersion). This paper presents the results of studying activation of titanium carbide by heat treatment method, which contributed to an increase in the main characteristics of nickel electroreduction. Barium sulfate is a promising dispersed material for composite coatings. This powder can be obtained with any dispersion as a result of an exchange reaction. In this work investigates the effect on the particle size of barium sulfate deposition conditions (time of mixing and pouring of reagents). The optimum conditions for obtaining barium sulfate are determined. Both powders can be used as a dispersed phase to obtain composite coatings with a nickel matrix.

Possibilities of Using Fly Ash with Other Industrial Waste to Obtain Geosorbents and Composite Materials

The authors have studied the conditions of using waste obtained after thermal and chemical processing of minerals (coal, apatite, etc.) and unused natural polymer lignin formed as a result of wood hydrolysis. It has been established that these wastes, individually and in various combinations, can be used as an effective geosorbent for lanthanum ions from wastewater, in the form of composite electrochemical coatings and in the manufacture of ceramic products. The degree of trapping of lanthanum ions from concentrated wastewater with a mixture of fly ash and hydrolytic lignin reaches 96%. Internal stresses and microhardness of composite electrochemical coatings (CEC) nickel – fly ash decrease with increasing thickness and content of fly ash in the nickel layer due to the presence of 4.23% iron fraction with increasing its strength. The use of fluorogips and fly ash in the manufacture of mixtures for the production of ceramic products, including red brick, gives positive results in reducing shrinkage during high-temperature processing of the composite.

Possibilities of Using Fly Ash with Other Industrial Waste to Obtain Geosorbents and Composite Materials

The authors have studied the conditions of using waste obtained after thermal and chemical processing of minerals (coal, apatite, etc.) and unused natural polymer lignin formed as a result of wood hydrolysis. It has been established that these wastes, individually and in various combinations, can be used as an effective geosorbent for lanthanum ions from wastewater, in the form of composite electrochemical coatings and in the manufacture of ceramic products. The degree of trapping of lanthanum ions from concentrated wastewater with a mixture of fly ash and hydrolytic lignin reaches 96%. Internal stresses and microhardness of composite electrochemical coatings (CEC) nickel – fly ash decrease with increasing thickness and content of fly ash in the nickel layer due to the presence of 4.23% iron fraction with increasing its strength. The use of fluorogips and fly ash in the manufacture of mixtures for the production of ceramic products, including red brick, gives positive results in reducing shrinkage during high-temperature processing of the composite.

Determination of composition of galvanic composites by microhardness method

Based on composite electrochemical coatings effect of content by volume of hard dispersed phase on coefficient of variation of microhardness has been considered. Besides model equation of relationship between content by volume of dispersed phase and coefficient of variation of microhardness has been worked out. The relation between the coefficient of variation of microhardness and volume content of a dispersed phase in a galvanic composite is established.