Surface Of Coating Layer Research Articles

Структура та властивості поверхневих шарів деформованого цирк¬нію, легованого Nb, Мо та В шляхом лазерної обробки поверхні

The phase composition and structure of the near-surface layers of zirconium ribbons subjected to laser treatment in the initial state and after alloying with B, Mo, Nb were studied. The distribution of microhardness values on the surface of the coating and changes in microhardness at different distances from the surface were analyzed. X-ray structural analysis of the surface layers was performed, and their phase composition was determined. The influence of β-stabilizing elements on changes in the phase composition was demonstrated. In the Zr—Mo coating, a phase transformation of Zr with bcc modification takes place. It is observed that small intermetallic particles of the ZrMo2 compound are released, which help to increase the hardness in the coating to the values of μ = 1200—1300. The content of niobium in the zirconium matrix in the Zr—Nb coating, calculated according to X-ray analysis, is 29,4% (at.) which is sufficient to stabilize the BCC lattice. The value of microhardness Hμ = 600—700 on the surface of the coating is typical for hardened zirconium with a bcc lattice. The hardness of the Zr—B coating on the surface reaches values of Hμ = 1600—1400, gradually decreases in the depth of the molten layer to Hμ = 1300 and sharply decreases outside the molten zone to Hμ = 300. Significant surface hardening of the coating is associated with a large amount of the strengthening phase ZrB2. As a result of the experiments, it was established that doping with niobium and molybdenum causes fundamental phase changes in the surface layer of coatings due to the stabilization of the β phase. This is important for protecting the surfaces of nuclear power and medical devices. The addition of B significantly increases the hardness due to the mechanism of dispersed strengthening, which contributes to the improvement of the wear resistance of the coatings. Keywords: laser processing, coating, phase composition, dispersed particles, hardness.

Detailed Investigation on LiNbO3-Coated Layer of Different Thicknesses on LiNi0.5Co0.2Mn0.3O2 Cathode Material for All-Solid-State Lithium Batteries

All-solid-state batteries (ASSBs) are very promising for next-generation energy storage technologies owing to several key advantages including higher power density, better thermal and electrochemical stability, and improved safety for electric vehicles [1, 2]. In this work, bulk-type ASSB cells were prepared with LiNbO3 coatings of different thicknesses, and their electrochemical behaviors at different upper cutoff voltages (upper cutoff potential ≥ 4.40 V) were first systematically compared by using Bulk-type ASSB cells. To eliminate the influence of additives, charge-discharge curves were recorded without conductive carbon or binders in the composite cathodes.A thicker coating caused three unfavorable electrochemical behaviors in the first three cycles: (1) a higher overpotential, (2) sluggish discharge kinetics, and (3) capacity fading. The measured electronic conductivity decreased drastically with increasing coating thickness, suggesting that this may have caused behaviors (1–3). To overcome this, a carbon additive was used to improve electronic transport in the composite cathode and successfully suppressed the aforementioned behaviors. Our findings indicate that the combination of a thick LiNbO3 coating on NCM523 and carbon additive can achieve synergistic effects to improve both the electrochemical properties and durability of ASSB cells.To further verify the cycle performance of the NCM523 cathode material with LiNbO3 layers of different thicknesses and uniformity, full-cell ASSBs consisted of a positive electrode and a graphite negative electrode separated by an SE has been fabricated. As a result, the cycle performance was greatly enhanced by increasing the thickness and uniformity of the LiNbO3 coated layer [3]. Our findings further demonstrate that a thick (more than 9 nm) and uniform coated layer (surface without uncoated area) displays outstanding electrochemical performance, especially cycle stability (capacity retention of 85.1% after 300 cycles at 60 ℃), indicating that this strategy is very effective for constructing high-performance NCM cathodes for sulfide-based ASSBs. 【 Acknowledgments 】 This study was supported by the SOLiD-NEXT project (JPNP23005) commissioned by the New Energy and Industrial Technology Development Organization (NEDO). 【 References 】 [1] Y. Kato, S. Hori, T. Saito, K. Suzuki, M. Hirayama, A. Mitsui, M. Yonemura, H. Iba, R. Kanno, Nat. Energy, 1 (2016), 16030.[2] M. M. Thackeray, C. Wolverton, E. D. Isaacs, Energy Environ. Sci., 5 (2012), 7854−7863.[3] W. S. K. Bong, A. Shiota, T. Miwa, Y. Morino, S. Kanada and K. Kawamoto, J. Power Sources, 577, 233259 (2023).

Features of thermal processes and the influence of pulsed heating of surface layers of titanium on the diffusion transfer of dopants during high-intensity ion implantation

Methods for modification of surface and near-surface layers of materials and coatings by ion beamshave prospects for application in many fields of science and technology. The method of high-intensityimplantation by high-power density ion beams with submillisecond duration involves significantpulsed heating of the irradiated target’s surface layer, followed by its rapid cooling due to heatremoval into the material due to thermal conductivity and the implementation of repetitively-pulsedradiation-enhanced diffusion of atoms to depths significantly exceeding the projective ion range. Thispaper considers features of thermal processes and the effect of pulsed heating of near-surface titaniumlayers on diffusion transfer under conditions of synergy of high-intensity titanium ion implantationand energy impact of a high-power density repetitively-pulsed beam on the surface to increase iondoping depth due to radiation-enhanced diffusion under conditions of limited heating of the entiresample. The paper presents the data of numerical simulation of dynamic changes in temperature fieldsin titanium and titanium self-diffusion under the action of ion beams with a submillisecond durationand a pulse power of tens of kW/cm2 and fluence of ions in a pulse 1.25×1015 ion/cm2.

Features of the structure and properties of surface layers of babbitt coatings after boundary mode of friction

Features of the structure and properties of surface layers of babbitt coatings after boundary mode of friction

Effect of thickness and uniformity of LiNbO3-coated layer on LiNi0.5Co0.2Mn0.3O2 cathode material on enhancement of cycle performance of full-cell sulfide-based all-solid-state batteries

Although LiNi0.5Co0.2Mn0.3O2 (NCM523) cathode active material (CAM) is considered to have application potential in sulfide-based all-solid-state batteries (ASSBs), CAM/solid electrolyte interfacial instability remains a significant limiting factor. To effectively improve the interfacial stability and long-term cycling performance, NCM523 cathode material was coated with LiNbO3 layers of different thicknesses and uniformity. As a result, the cycle performance was greatly enhanced by increasing the thickness and uniformity of the LiNbO3-coated layer. Our findings further demonstrate that a thick (≥9 nm) and uniform coated layer (surface without uncoated area) displays outstanding electrochemical performance, especially cycle stability (capacity retention of 85.1% after 300 cycles at 60 °C), indicating that this strategy is very effective for constructing high-performance NCM cathodes for sulfide-based ASSBs. Moreover, the performance improvement mechanism was investigated by electrochemical impedance spectroscopy (EIS) combined with XPS and TEM-EDX analysis. The findings reveal that controlling the thickness and uniformity of the coating material plays a crucial role in the effective suppression of interface side reactions and resultant performance degradation in NCM cathodes.

Layer-by-Layer Engineered Flexible Functional Film Fabrication with Spreadability Control in Roll-to-Roll Manufacturing.

A roll-to-roll manufacturing system performs printing and coating on webs to mass-produce large-area functional films. The functional film of a multilayered structure is composed of layers with different components for performance improvement. The roll-to-roll system is capable of controlling the geometries of the coating and printing layers using process variables. However, research on geometric control using process variables is limited to single-layer structures only. This study entails the development of a method to proactively control the geometry of the upper coated layer by using the lower-layer coating process variable in the manufacture of a double-coated layer. The correlation between the lower-layer coating process variable and upper coated layer geometry was examined by analyzing the lower-layer surface roughness and spreadability of the upper-layer coating ink. The correlation analysis results demonstrate that tension was the dominant variable in the upper coated layer surface roughness. Additionally, this study found that adjusting the process variable of the lower-layer coating in a double-layered coating process could improve the surface roughness of the upper coating layer by up to 14.9%.

Microstructure of the deposited NiCrBSiC coating after laser polishing

The structure of the surface layers of NiCrBSiC coatings obtained by powder laser cladding and subsequent laser polishing with a multichannel CO2 laser has been studied. XRD and TEM / STEM showed that the coatings are a γ-Ni matrix with Ni3B, Cr3C2 and Ni3Si precipitates. It was shown that the matrix of the coating after laser cladding has a high density of dislocations, which form networks. XRD evidences a decrease in the number of the precipitates after laser polishing and TEM / STEM demonstrated a decrease in the density of dislocations and the appearance of nanostructured γ-Ni layers in the form of flat elongated plates. The width of nano-grains is ≈20 nm near the interface and increases with distance from it. Microhardness measurements showed an increase from 4.4 to 5 GPa after laser polishing.

The effect of the multiplicity of frictional action on the micromechanical properties of NiCrBSi-coatings

The paper investigates the effect of the number of passes (1 or 2) of an indenter made of fine cubic boron nitride during friction treatment of PG-SR2 and PG-10N-01 NiCrBSi-coatings on the micromechanical properties of their surface layers. The friction treatment of the coating surface under all the process conditions studied, in comparison with the initial polished state, increases the strength characteristics of the coating surface layer and the parameters indicating the resistance of the material surface to elastic-plastic deformation. The effect of the number of indenter passes during surface friction treatment on the strength characteristics is found to be more significant for the softer and more ductile PG-SR2 coating than for the PG-10N-01 coating. This is attributed to the higher strain hardenability of the former.

Improvement of tribological properties of detonation carbosilicide coatings with subsequent pulsed-plasma treatment

This work considers the results of research of mechanical and tribological properties of surface layer of Ti3SiC2coatings after exposure to pulsed-plasma energy flows. Varying of technological parameters of pulsed-plasma treatment is made by changing the distance of pulse exposure. The analysis of the obtained results shows that the pulsed-plasma treatment technology makes it possible to improve the properties of Ti-SiC based coatings by strengthening the deposited compositions by modifying the structure with an increase in the number of МАХ-phases. It is established that the modification of the structural and phase state of the near-surface layers of the carbosilicide coatings leads to a change in their mechanical properties: an increase in the surface microhardness up to 1.8 times, a decrease in the dry friction coefficient by 1.5-2.0 times and an increase in wear resistance by 2.5 times. Based on the XRD analysis, it is established that the improvement of mechanical and tribological properties of Ti3SiC2 detonation coatings as a result of pulsed-plasma treatment is associated with phase transformations in the surface layer, in particular with an increase in the Ti3SiC2 phase content.

Structural Phase Transformations in Detonation Coatings Based on Ti3SiC2 after Pulse-Plasma Effect

This work presents the results of the study on the effect of pulse-plasma treatment on the structural-phase states of the surface layer of detonation coatings based on Ti3SiC2. Structural-phase studies were carried out by three main methods: scanning electron microscopy, transmission electron diffraction microscopy on thin foils and X-ray structural analysis. It was determined that after the pulse-plasma treatment, an increase in the intensity of the Ti3SiC2 peaks was observed, and the appearance of new reflections (101, 102, 112, 204, 1110, 0016) of this phase was detected, which indicates the increase in the MAX-phase content. It was determined that after the pulse-plasma treatment, the fraction of voids (pores) and the particle area decreased and the microstructure became more homogeneous, which resulted in the densification of the Ti3SiC2-based detonation coating. It was found that the process of detonation spraying with subsequent pulse-plasma treatment resulted in the formation of a Ti3SiC2-based coating, with TSC carbosilicide (Ti3SiC2) 0] plane reflexes, lamellar layered structure, and reduced porosity.

Микроструктура и остаточные напряжения многослойных покрытий ZrN/CrN, полученных плазменно-ассистированным вакуумно-дуговым методом

Introduction. The current state of the art in the field of hard coatings application requires the formation of nanostructured compositions using different chemical elements. Modern hard coatings are able to combine different properties such as high hardness, wear resistance, corrosion resistance. At present, coatings formed by layer-by-layer deposition of zirconium and chromium nitrides are promising. When depositing combinations of chemical elements on various substrates, studies are required aimed at investigating its microstructure and, mainly, residual stresses formed during the deposition of multilayer coatings. The purpose of this work is to investigate the structural-phase state and residual stresses of ZrN/CrN system coatings formed by plasma-assisted vacuum-arc method from the gas phase. Research methods. Samples with coatings of zirconium and chromium nitrides deposited on substrates of hard alloy VК8 are investigated. Transmission electron microscopy is used to study the microstructural characteristics of multilayered coatings and X-ray diffraction analysis is used to quantify macroscopic stresses. Results and discussion. Based on the experimental results obtained it is found that changing the modes of deposition of multilayer ZrN/CrN coatings with regard to rotation speeds of table and substrate holder leads to variations in microstructure, morphology and internal stresses of surface layers of multilayer coatings. It is shown that by changing conditions for the multilayer coating deposition the possibilities of forming ZrN/CrN coatings on the substrate made of VK8 alloy with nanoscale thickness of coating layers open up. X-ray diffraction analysis indicates mainly insignificant stresses, and at high table and substrate rotation speeds – high compressive stresses in the multilayer coating. Transmission electron microscopy revealed that CrN and ZrN coatings have a common multilayer coating growth texture at low rotation speeds, and at high speeds a textural misorientation of the phases of the coating layers is observed. Based on the results obtained it is possible to recommend coatings of ZrN/CrN system as hard coatings.

Evaluation of the effect of maltodextrin and hydroxyethyl cellulose solution containing ZnO and Fe2O3 nanoparticles on the CO2 release in sodium bicarbonate coating process

Coating is a rapidly extending technology; especially in food and pharmaceutical industries. The coating process of sodium bicarbonate using ZnO and Fe2O3 nanoparticles (NPs) in aqueous solutions of maltodextrin (MD) and hydroxyethylcellulose (HEC) as wall materials has been studied in this work. The best operating conditions obtained by factorial design were the fluidization air flow rate of 100 m3/h, spraying pressure of 4 bars, drying air temperature of 60 °C, MD concentration of 30 % and HEC concentration of 0.1 %. The introduction of the NPs into the coating solution provides a heterogeneous surface, which enforces the wall material to a more uniform and faster crystallization. The applied conditions have been shown to be efficient for the coating process investigated in this study since they improve the coating characteristics such as CO2 release reduction, which is the most important one. CO2 release was reduced from 4 % for coated powders with no NPs in the coating solution to 2.4 % and 3.5 % for coated powders with Fe2O3 and ZnO NPs in the coating solution, repectively. The adsorption–desorption of N2 gas implies that the pore sizes of the coating layer surface have been significantly decreased by adding NPs to the coating solution.

After-Machining Surface Layer of Composite Coatings Obtained by Thermal Spraying

The surface of machine elements is changed to improve their mechanical properties. Ceramic-metal composite coatings are mainly used to increase the durability of machine parts. Therefore, new materials are constantly searched for application in the future development of metal and ceramic composites. The nickel and iron elements are usually used as a base and Al2O3 as tough particles. The welding technology for applying alloy and composite coatings is widely used. The common technology used to apply composite coatings is thermal spraying. It is a simple technology and very useful for the production or regeneration of machines. The surface layer is very rough and porous after applying the coating by thermal spraying. In order to obtain the proper surface quality of alloy and composite coatings, after-machining should be used. Many parts of machines strive to achieve an accurate surface. Therefore, a certain roughness is often required. The arithmetic mean of the ordinates of the surface roughness profile was (Ra = 0.16–1.25 μm). The article presents the influence of finishing on the roughness of the surface layer of the coating. After plastic working and machining, the roughness of the surface layer of the coating was reduced. However, it can be seen that, after plastic working, there is a strengthening of the surface layer of the coating and most of the pores were closed.

Protective coating of highly porous alginate aerogel particles in a Wurster fluidized bed

Alginate aerogel particles were successfully coated with a copovidone and hydroxypropyl cellulose based polymer in a Wurster fluidized bed. The results indicate that the pores of aerogels were not damaged during the process. Several sets of experiments were conducted at three different temperatures and atomizing air pressures. Coating time for all the runs ranged from 5 min to 40 min and the coating thickness ranged from 12.4 ± 4.6 μm to 170.6 ± 43.3 μm.Changing bed temperature led to significant changes in coating thickness whereas both bed temperature and atomizing pressure affected coating layer surface morphology. The smoothest coating layer surface and the highest coating efficiency which was 69.2 ± 0.4% were achieved at 50 °C with 1.7 bar atomizing pressure. At this condition, the coating layer thickness increased linearly with coating time.

Численное моделирование динамики температурных полей в монокристаллическом кремнии при импульсно-периодической высокоинтенсивной ионной имплантации и энергетическом воздействии пучка на поверхность

Methods to modify surface and near-surface layers of materials and coatings by ion beams are used in many fields of science and technology. The method of high-intensity implantation by high-power density ion beams with submillisecond duration involves significant pulsed heating of the irradiated target’s near-surface layer, followed by its rapid cooling due to heat transfer into the material due to thermal conductivity and the implementation of repetitively-pulsed radiation-enhanced diffusion of atoms to depths exceeding the projective ion range. Using the numerical simulation, this work studies the dynamics of changes in temperature fields into silicon wafer under single-pulse and repetitively-pulsed exposure to submillisecond titanium ion beam with a pulsed power density in the range up to 109 W/m2. The conditions are determined under which the temperature in the ion-doped layer will correspond to the conditions of radiation-stimulated diffusion of the implanted element, and the temperature in the matrix material will not deteriorate its microstructure and properties.

Additive manufacturing technologies of tool electrodes

The experience of using additive technology in relation tocombined methods of tool manufacturing with the impact of electromagnetic and other types of fields on the process., where there are completely or partially no traditional mechanical effects on the tool part, which must have high mechanical strength, wear resistance. It is shown that the field of use of additive technologies is much wider than it was previously accepted., and mainly covers modern flexible-structured production of such branches of mechanical engineering, where there is a constant updating of products and the technological process is based on the production of limited batches of high-tech products, as a rule, according to preliminary orders of the consumer. It is proved that the scientific foundations of the multilayer formation of parts created to date are legitimate for coating, controlled layer-by-layer changes in the performance characteristics of materials, the creation of means of cooling the hot zone of aircraft engines in aerospace engineering, where multilayer templates with specified performance characteristics can be used as a data carrier. A new (according to the authors’ patent) direction of manufacturing unprofiled electrode tools with giving them useful properties of a profile tool is considered. The ways of solving the problem of controlling the operational characteristics of products by creating parts from conjugate layers, the properties of which are formed by optimizing technological modes, are proposed. The ways of effective finishing of combined methods of surface layers of coatings with preservation of useful performance qualities of parts obtained using additive technologies are studied.

Effect of Electric Pulse Treatment on Hot-Dip Aluminizing Coating of Ductile Iron.

In this paper, hot-dip aluminizing of ferrite nodular cast iron was carried out after treating liquid aluminum with different electrical pulse parameters. Compared with that of conventional hot-dip aluminizing, the coating structure of the treated sample did not change, the surface was smooth and continuous, and the solidification structure was more uniform. When high voltage and large capacitance were used to treat the liquid aluminum, the thickness and compactness of the coating surface layer increased. The thickness of the alloy layer decreased, and, the compactness and the micro hardness increased, so the electric pulse had a certain inhibition on the formation of the alloy layer. The growth kinetics of the alloy layer showed that the rate-time index decreased from 0.60 for the conventional sample to 0.38 for the electric pulse treated sample. The growth of the alloy layer was controlled by diffusion and interface reaction, but only by diffusion. The AC impedance and polarization curves of the coating showed that the corrosion resistance of hot-dip coating on nodular cast iron was improved by electric pulse treatment.

Improvement of high frequency giant magnetoimpedance effect in CoFeSiB amorphous ribbon with vanishing magnetostriction by electrodeposited Co coating surface layer

The influence of a ferromagnetic cover layer on giant magnetoimpedance (GMI) effect in nearly-zero magnetostrictive Co66.5Fe3.5Si12.0B18.0 amorphous ribbon after being surface coated by an electrodeposited Co layer of 10 μm in thickness, has been studied in the high frequency range between 10 MHz and 1.5 GHz. Longitudinal MOKE measurements performed on both kind of samples reveal the influence of exchange coupling interaction at the interface between the magnetic amorphous ribbon and electrodeposited Co coating layer, which is sensitive to the skin depth effect at high ac current frequency values. Comparison between GMI responses of the Co coated amorphous ribbon and the as-cast sample is provided. A more sharp and well defined double-peaks dependence of impedance on magnetic field, but with lower peaks intensity, is observed for the Co coated ribbon in the frequency range of 10–100 MHz, while the peaks intensity is higher than that observed in the as-cast ribbon at the high frequency value of 1 GHz due to the higher resistance of the Co electroplated layer than the core one. The influence of a dc bias drive current on the GMI response in both amorphous ribbons (as-cast and Co layered) is analyzed, which originates the removal of magnetic domain structure from both, the as-cast and Co-coated ribbons, giving rise more sensitive GMI effect. CoFeSiB amorphous ribbon with vanishing magnetostriction can achieve improved high frequency magnetic properties after being surface coated with electrodeposited ferromagnetic layers, as outstanding candidates for electromagnetic and magnetomechanical engineering applications.

Study of Coatings Formed on Zirconium Alloy by Plasma Electrolytic Oxidation in Electrolyte with Submicron Yttria Powder Additives

Coatings with thickness 40 to 150 μm were formed by plasma electrolytic oxidation (PEO) on the zirconium alloy Zr-1Nb (Zr-1% Nb) in the slurry electrolyte containing 9 g/L Na2SiO3 5H2O, 5 g/L Na(PH2O2) and 6 g/L submicron Y2O3 yttria powder during 60 min under the AC electrical mode at current densities 20; 30 and 40 A/dm2. The surface morphology, structure, composition, and corrosion-protective ability of the formed coatings have been analyzed. At PEO current density 30 A/dm2, a predominantly tetragonal phase of zirconia was formed in coatings. Increasing the PEO current density up to 40 A/dm2 promoted the formation of the coating surface layer containing submicron yttria particles. Electrochemical polarization studies in 0.5% LiOH solution showed that PEO coatings demonstrated high corrosion-protective ability. The dependence of the polarization currents on the PEO current density was found to be inconsequential.

Experimental investigation of cryogenic flow quenching of horizontal stainless steel tubes

Cryogenic fluid is frequently used in such fields as cryogenic cooling, food engineering and chemical process, etc. It has been understood in pool quenching experiments that a thin low-thermal-conductive coating layer on the wall can greatly improve the cooling performance, while less is known about the flow quenching. In the present study, the experiments are conducted to investigate cryogenic flow quenching of the horizontal stainless steel tubes with the Teflon coating layers on the inner wall. To explore the influence of the coating layer on the quenching performance, three Teflon coating layers of distinct thicknesses are fabricated on the inner wall of the stainless steel tubes, and the quenching efficiency and quenching heat transfer performance are compared with those of the bare tube. It is shown that the thin coating layer on the inner tube wall can significantly shorten quenching time and reduce the consumption of liquid nitrogen at different inlet pressures. The quenching time of the Teflon-coated tube is reduced by up to about 78.5%, and the maximum quenching efficiency of the Teflon-coated tube is above 50.0% compared with 8.0% of the bare tube. The improvement of quenching performance in the present study is ascribed to the fact that the sharp temperature drop of the Teflon coating layer surface upon cooled by liquid nitrogen makes the transition boiling with higher heat transfer coefficient replace film boiling at a higher average wall temperature, leading to a reduction in quenching time and an improvement in quenching efficiency.