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Achieving long-wavelength infrared (LWIR) cameras with high sensitivity and shorter exposure times faces challenges due to series reflections from high-refractive index lenses within compact optical systems. However, designing effective antireflective coatings to maximize light throughput in these systems is complicated by the limited range of transparent materials available for the LWIR. This scarcity narrows the degrees of freedom in design, complicating the optimization process for a system that aims to minimize the number of physical layers and address the inherent large refractive mismatch from high-index lenses. In this study, we use discrete-to-continuous optimization to design a subwavelength-thick antireflective multilayer coating on high-refractive index Si substrate for LWIR cameras, where the coating consists of few (e.g., five) alternating stacks of high- and low-refractive-index thin films (e.g., Ge-YF3, Ge-ZnS, or ZnS-YF3). Discrete optimization efficiently reveals the configuration of physical layers through binary optimization supported by a machine learning model. Continuous optimization identifies the optimal thickness of each coating layer using the conventional gradient method. As a result, considering the responsivity of a LWIR camera, the discrete-to-continuous strategy finds the optimal design of a 2.3-μm-thick antireflective coating on Si substrate consisting of five physical layers based on the Ge-YF3 high-low index pair, showing an average reflectance of 0.54 % within the wavelength range of 8–13 μm. Moreover, conventional thin-film deposition (e.g., electron-beam evaporator) techniques successfully realize the designed structure, and Fourier-transform infrared spectroscopy (FTIR) and thermography confirm the high performance of the antireflective function.

Achieving long-wavelength infrared (LWIR) cameras with high sensitivity and shorter exposure times faces challenges due to series reflections from high-refractive index lenses within compact optical systems. However, designing effective antireflective coatings to maximize light throughput in these systems is complicated by the limited range of transparent materials available for the LWIR. This scarcity narrows the degrees of freedom in design, complicating the optimization process for a system that aims to minimize the number of physical layers and address the inherent large refractive mismatch from high-index lenses. In this study, we use discrete-to-continuous optimization to design a subwavelength-thick antireflective multilayer coating on high-refractive index Si substrate for LWIR cameras, where the coating consists of few (e.g., five) alternating stacks of high- and low-refractive-index thin films (e.g., Ge-YF3, Ge-ZnS, or ZnS-YF3). Discrete optimization efficiently reveals the configuration of physical layers through binary optimization supported by a machine learning model. Continuous optimization identifies the optimal thickness of each coating layer using the conventional gradient method. As a result, considering the responsivity of a LWIR camera, the discrete-to-continuous strategy finds the optimal design of a 2.3-μm-thick antireflective coating on Si substrate consisting of five physical layers based on the Ge-YF3 high-low index pair, showing an average reflectance of 0.54 % within the wavelength range of 8–13 μm. Moreover, conventional thin-film deposition (e.g., electron-beam evaporator) techniques successfully realize the designed structure, and Fourier-transform infrared spectroscopy (FTIR) and thermography confirm the high performance of the antireflective function. [ABSTRACT FROM AUTHOR]

In this work, the adhesive and tribological characteristics of (TiZrNbYAl)N multilayer coatings were studied. The main goal of this work is to assess the influence of the number of layers on the adhesive and tribological characteristics of the (TiZrNbYAl)N coating deposited on 12Х18Н9Т steel substrates. A study of the distribution of elements over the depth of coatings using Auger electron spectroscopy showed that chemical elements are distributed quite evenly over the cross section of the coatings and the element distribution curves have sharp peaks. The presence of iron in the coating composition at a depth of more than 2 microns on the coating side indicates that an increase in electrical displacement ensures reliable adhesion of the coating to the steel substrate, which is confirmed by the results of testing the coatings for adhesive strength. An increase in the application time of each individual layer at Upp=-100 V and P= 4×10-3 Torr leads to an uneven distribution of elements throughout the thickness of the coatings and the formation of a relatively wide transition coating-substrate layer. Tests of the adhesive strength of coatings have shown that all coatings wear out when scratched, but do not peel off, i.e., they are destroyed by a cohesive mechanism associated with plastic deformation and the formation of fatigue cracks in the coating material. Different coating modes correspond to different values of acoustic emission depending on the load. It was determined that the coatings obtained at Upp =-100 V; P = 4×10-3 Torr showed high adhesive strength and some degree of delamination in the scratch area at the maximum test load. The results of tribological studies showed that (TiZrNbYAl)N coatings have a high friction coefficient, the average value of which is μ=0.85-0.95. Such values can be explained by the high roughness of wear tracks due to cohesive destruction of coatings. [ABSTRACT FROM AUTHOR]

In this work, TiAlSiN/NiCr multilayer coatings with different modulation periods were deposited by cathodic-arc techniques, which combined filtered cathode vacuum arc (FCVA) and cathodic-arc ion plating (CAIP) techniques to deposit sublayers at different bias voltages. The nanoscale multilayer coating (TiAlSiN: 88 nm; NiCr: 9 nm) exhibited excellent oxidation resistance and thermal stability. Annealed coatings at 900 °C in air for 1 h, the thickness of the oxide layer of N32 coating is only 0.91 μm and the increase in coating thickness was only 9.01%, while the thickness of oxide layer of monolayer TiAlSiN coating is 3.02 μm and thickness increasing of 122.28%. Due to the existence of numerous interfaces, the N32 coating exhibited the lowest wear rate of 1.92 × 10−7 mm3N−1m−1 at 600 °C under abrasive wear and adhesive wear mechanisms. In parallel, a new AlNi intermetallic compound with excellent thermal stability was characterized by high-resolution transmission electron microscopy (HRTEM) at the coating interfaces. This compound is derived from different cathodic-arc techniques and bias voltages used to deposit coatings, which provides a reference for the structural design of coatings facing thermal environments. [ABSTRACT FROM AUTHOR]

Working conditions exert an important influence on the tribological properties of protective coatings, thus affecting the wear resistance of workpieces. In this work, a TiAlSiN hardness-modulated multilayer coating with a good match of strength and toughness was deposited on WC-Co substrates. The adhesive wear played a predominant role under the condition of a larger normal load and lower velocity, leading to the formation of a third body layer composed of compressed and lubricating oxides. As a result, the wear rate of the coating tested at 20 N reduced by 23% of that tested at 5 N. Instead, abrasive wear was more manifest, leading to the formation of big-size abrasives, and thus the wear rate increased by 2.8 times while the velocity elevated from 4 mm/s to 16 mm/s. A full factorial analysis of the wear behaviors, including the nanohardness and roughness of the wear track, and the friction coefficient and wear rate of the coating, offered good guidance for the comprehension of the wear form of the TiAlSiN multilayer coating. The results demonstrated the optimization of multilayer structures for TiAlSiN coatings to attain better wear resistance under coupling conditions of normal load and velocity: harder or more lubricated sublayers. [ABSTRACT FROM AUTHOR]

Many studies about the multilayer coating have indicated the effects of reflection phase, reflection group delay (GD), and reflection group delay dispersion (GDD) characteristics. Some overlook the importance of studying complex statistical coefficients and their role in comparing the results of optical designs and realize how important information is in analyzing data. In statistics, one can learn various techniques for working with data. This paper goes into a detailed study of multilayer stacks' dispersive properties for two mirror designs depending on MATLAB programs based on statistical parameters to evaluate the reflectance for the ZnS/MgF mirror. Two samples with a quarter wavelength optical thickness were prepared, specially designed for 632.8 nm He-Ne laser mirrors. For the designed mirror, the value of the reflectivity of the thirteen-layer ZnS/MgF mirror is 99.34 , while for the seven-layer ZnS/MgF mirror is 96.57 . This study presents greater detail on statistics and realized data topics when designing multilayer coating, including mean, median, mode, and standard deviation (STD). The reliability and accuracy of the data can be verified by calculating the standard deviation. [ABSTRACT FROM AUTHOR]

The paper deals with multilayer CrN/AlN coatings fabricated by the plasma-assisted vacuum-arc deposition onto a WC–8Co alloy substrate. The use of a screen for separating alternately Cr and Al flows, allows to create a multilayer coating structure with CrN and AlN nanolayers. The X-ray diffraction analysis shows that the structure of obtained coatings consists of CrN and AlN phases with the face-centered cubic crystal structure. It is found that a 5 rpm rotation speed of the turning table is the best and provides the most appropriate ratio between the thickness of CrN and AlN layers and the ratio between their phase compositions. This allows minimizing the wear rate intensity of the coatings. The in situ synchrotron X-ray diffraction analysis confirms the presence of CrN and AlN phases in the temperature range of ~1075 to 1080°C. [ABSTRACT FROM AUTHOR]

This study investigates an approach to temperature sensing by integrating Titanium Aluminum Nitride (TiAlN), originally engineered for wear and corrosion applications, as a temperature sensor within a multilayered thin film system. A nitride multilayer system was developed by physical vapor deposition (PVD) using a single four-target magnetron sputtering chamber; intermediate vacuum interruption steps were employed for masking procedures. The multilayer architecture design aimed to provide the sensor layer with mechanical protection and electrical shielding. Structural and electrical characterization of the TiAlN single layer revealed semiconductor behavior and stable electrical resistance up to 750 °C, with minimal signal stabilization requirements. Despite the higher Al content, the TiAlN temperature sensor exhibited a cubic crystal structure characterized by diffuse nanolayers, resulting from a two-fold rotational deposition and target configuration. A detailed examination of the multilayer system cross-section containing the TiAlN sensor was conducted using scanning transmission electron microscopy (STEM). The analysis revealed its columnar morphology with the presence of typical PVD growth defects, including voids and droplets. While the presence of these defects may impact the electrical characteristics of the sensor, the selected experimental conditions effectively maintained the structural integrity of the multilayer system despite the vacuum interruptions caused by masking procedures. Validation experiments confirmed the functionality of the multilayer system for temperature measurements up to 400 °C. The signal acquisition system addressed room temperature resistance variations and low sensitivity (thermistor coefficient ∼100 K), resulting in a measured error of approximately 6%. This study demonstrates promising results of TiAlN as a temperature sensor within a multilayered system, expanding its range of potential applications.

The paper deals with CrAlYN/CrAlYO multilayer coatings obtained by the plasma-assisted vacuum-arc deposition onto a WC–8Co alloy substrate. It is investigated how the layer number and thickness of 16- and 32-layer coatings with the thickness of ~240 and ~120 nm, respectively, affect the phase composition, crystal structure parameters, roughness, surface morphology, and physical and mechanical properties. The X-ray diffraction analysis shows that the obtained multilayer coatings have a multiphase structure consisting of nitride CrN and AlN and oxide Cr2O3 and AlYO3 phases. It is found that the roughness of the 32-layer CrAlYN/CrAlYO coating is almost 2 times lower than that of the 16-layer coating. It is shown that the larger number of layers and their lower thickness have a positive effect on physical and mechanical properties of the coatings. The hardness of the 32-layer coating increases by 52%. The synchrotron X-ray diffraction analysis of the 32-layer CrAlYN/CrAlYO coating shows its thermal stability up to ~1020°C during heating in air, while during heating in vacuum, its thermal stability keeps constant up to at least 1500°C. [ABSTRACT FROM AUTHOR]

Multilayer coatings have the advantage of controlling residual stress that is difficult to achieve with monolayer and bi-layer coatings. In this context, finite element modelling was employed to verify the effect of the design of the magnetron sputtered multilayer Ti/AlN coatings on the distribution of residual stress. Literature survey shows that most of the models in this area effectively show the residual stress arising due to thermal effects. However, that due to intrinsic effect is often neglected. In this work, the intrinsic stress was calculated using the model proposed by Windischmann and the results were incorporated in the finite element model to evaluate the total residual stress. The model was validated for residual stresses evaluated by X-ray diffraction, published by Sprute et al. It was applied for a variety of designs with bilayer and multilayer coatings (up to 20 layers) with graded and constant layer thicknesses. It was found that for the same total thickness of coatings, the residual stress is influenced by the number of layers and the thickness of individual layers. Moreover, the presence of the ductile Ti layer sandwiched between the ceramic nitride layers provides the perfect design for reducing residual stress and improving the life of the tool. [ABSTRACT FROM AUTHOR]

The coating's purpose is to enhance the tribological conditions at the tool-workpiece and chip–tool interfaces. In comparison to commercial coatings, the current work offers a coating for high-speed steel (HSS) equipment that is thinner and less expensive. A single-point AISI T6 high-speed steel tool having a square cross-section was used to prepare the cutting inserts for turning purpose. The best conditions for coating the HSS insert with ceramic oxides using the sol–gel process were determined. These precursor conditions involved: viscosity, PH, dispersion materials, and the ageing period. The deposition conditions were the number of coating cycles, the immersion time, the calcination temperature, and dry temperature that affects the layer thickness, adhesion, surface roughness, and homogeneity for coating layer. Titanium tetra-isopropoxide (TTIP), a catalyst HCl, and a dispersion material (triethanolamine) were employed to prepare the precursor (titanium hydroxide). The PH, the viscosity, and the ageing time, of the produced precursor were 6.46 and 8.74 cP, and 6 h, respectively. After the dip coating of the cutting inserts for 5 sec immersion time and two number of coating cycle in titania precursor, the inserts were dried at 355℃ for 1 hour. Then, to form the alumina coating film, the inserts were dipped in the alumina hydroxide sol, which was made by combining aluminium isopropoxide IPA, deionised water H2O, and nitric acid (HNO3). The produced precursor had a PH of 5.83, viscosity of 8.11 cP, with an ageing time of 12 h. The immersion time and number of coating cycles in the alumina precursor were 25 sec, and two, respectively. The inserts were dried at 355℃ for 1 hour, then calcinated at 500°C for 2 h to achieve the appropriate film thickness for the machining test. The study investigates the thermal and tribological properties of coated with single and multiple layers as well as uncoated cutting inserts. The results indicated that the hardness is 1393.3 HV with a thickness of 6 µm for multilayer. X-ray diffraction-phase analysis confirms the presence of phases originating from the coatings and substrate. EDS analysis of the chemical composition of the studied coatings indicates the presence of titanium and aluminium, as well as oxygen. Atomic force microscopy (AFM) was used to examine the surface morphologies of coated surfaces. Scratch hardness is measured in GPa and differs between monolayers (alumina) and multilayers (titania/alumina). Monolayer alumina has a value of 0.374 GPa, whereas multilayer alumina/titania has a value of 1.010 GPa. Multilayer coated inserts, on the other hand, have a lower wear rate than monolayer coated and uncoated inserts. The thermal expansion coefficient of the titania layer is often relatively near to the thermal expansion coefficient of the bulk HSS (11 × 10−6, 13 × 10−6 1/K) that reduces mismatch between substrate HSS and top coating layer (alumina). [ABSTRACT FROM AUTHOR]

Layer-by-layer deposition of zirconium and chromium nitrides is a promising material for hard coatings; however, this process is complex and not well documented in the literature. The problem lies in the difficulty of depositing thick layers of multi-component coatings with different physical characteristics, particularly the coefficient of linear thermal expansion (CLTE). As coatings undergo thermal exposure during deposition and use, different CLTEs can lead to cracking and product failure. The aim of the study is to perform on-site analysis of ZrN/CrN multilayer coatings using synchrotron radiation and investigate the micro-stress behavior of coatings deposited on a VK8 alloy substrate at temperatures up to 750°C. X-ray analysis and methods such as CLTE and qualitative determination of type II micro-stresses were used in the study. The results show changes in the characteristics of multilayer coatings during heating, the ability to determine the coefficient of thermal expansion, and qualitative determination of micro-stresses. The study provides recommendations for the application of multilayer coatings with specified characteristics. [ABSTRACT FROM AUTHOR]

The effects of layer number (2, 4, and 6-layer) and sintering temperature (800, 900, 1000, and 1100 °C) on the microstructure, wear, and corrosion properties of Al 2 O 3 –TiO 2 multilayer coatings deposited on 316L stainless steel plates using the sol-gel dip coating technique were investigated. The wear characteristics were measured through ball-on-disc type dry sliding tests using an Al 2 O 3 ball under a 1 N load, whereas the corrosion features were determined by potentiodynamic polarization tests conducted in a 3.5 wt% NaCl solution. Anatase, rutile, α-Al 2 O 3 , and γ-Al 2 O 3 phases were obtained in the hybrid coatings, depending on the sintering temperatures. However, at 1100 °C, the coating did not adhere well to the substrate due to passive oxide film formation on the 316L plate, leading to spalling. Besides, the surface homogeneity deteriorated in the 6-layer coated sample due to higher organic removal and residual stresses. The corrosion rate decreased with the increasing number of layers, but the sensitivity to corrosion varied due to changes in surface properties. The 4-layer coated sample sintered at 1000 °C achieved the highest wear strength (improved by up to 71.1%) and corrosion resistance (increased by up to 90.4%) due to its decreased porosity and homogeneously distributed finer particles. [ABSTRACT FROM AUTHOR]

The versatility of sol–gel systems makes them ideal for functional coatings in industry. However, existing coatings are either too thin or take too long to cure. To address these issues, this paper proposes using an atmospheric pressure plasma source to fully cure and functionalize thicker sol–gel coatings in a single step. The study explores coating various substrates with sol–gel layers to make them scratch-resistant, antibacterial, and antiadhesive. Microparticles like copper, zinc, or copper flakes are added to achieve antibacterial effects. The sol–gel system can be sprayed on and quickly functionalized on the substrate. The study focuses on introducing and anchoring particles in the sol–gel layer to achieve an excellent antibacterial effect by changing the penetration depth. Overall, this method offers a more efficient and effective approach to sol–gel coatings for industrial applications. In order to achieve a layer thickness of more than 100 µm, the second part of the study proposes a multilayer system comprising 15 to 30 µm thick monolayers that can be modified by introducing fillers (such as TiO2) or scratch-resistant chemicals like titanium isopropoxide. This system also allows for individual plasma functionalization of each sol–gel layer. For instance, the top layer can be introduced with antibacterial particles, while another layer can be enhanced with fillers to increase wear resistance. The study reveals the varying antibacterial effects of spherical particles versus flat flakes and the different scratch hardnesses induced by changes in pH, number of layers, and particle introduction. [ABSTRACT FROM AUTHOR]

The hypothesis of the present study is that thin multiple layer coatings on paperboard from the aqueous solutions of poly(vinyl alcohol) (PVOH) at high machine speeds is more effective in terms of barrier properties than one or two thick layers. The objectives included attempts to use surface roughness parameters to understand the coating process and mechanisms behind coating defects. The present study is focused on pilot-scaled PVOH coating onto uncoated paperboard at machine speeds of 400 m/min. The multiple coating operation was carried out in six passes with a dry coat weight of about 1 g/m2 in each layer. The concept of thin multiple coatings resulted in coated surfaces without detected pinholes and with Kit rating 12 after only two thin layers. However, the oxygen transmission rates were still fairly high (100 ± 89 cm3/m2 day atm) after six layers, and some coating defects (such as craters and cracks) could be identified. The analyses of surface structure indicated that the surface properties are affected by water uptake during the coating processes. The compression of paperboard beneath the metering element seemed to be required to achieve homogeneous thin layers. However, an analysis of defects revealed flaws and inhomogeneities near objects protruding from the surface, such as surface fibers and craters, caused by blistering. For rough paperboard substrates, the desired barrier properties may require a careful balance between sufficient compression for fiber coverage and gentle compression in order to avoid defects near craters and surface fibers. [ABSTRACT FROM AUTHOR]

Gray cast iron (GJL) is known for its excellent damping property and high thermal conductivity, thanks to its unique lamellar graphite and pearlite structure. In a recent study, laser metal deposition (LMD) was explored as a potential process to enhance the corrosion resistance and wear mechanism of this tribological system. The focus was on laser cladding of gray cast iron using two different of stainless-steel materials, namely 430L and 316L, combined with TiC and WC particles. To create the samples, a multilayer coating system was employed. A comparative analysis of the microstructures was performed to understand the interaction of the laser beam with the material (composite materials). Surface properties were then characterized using light microscopy and electron microscopy (SEM) before and after subjecting the samples to a shock corrosion test, simulating automotive conditions. Additionally, phase analyses were performed at the interfaces between the coatings and the substrate, with particular attention given to the behavior of the graphite lamellae at these interfaces. This study aims to provide valuable insights into the potential improvements that can be achieved through laser cladding on gray cast iron, specifically in terms of corrosion resistance and wear mechanisms. By analyzing the microstructures and surface properties, researchers can gain a better understanding of the performance and durability of the coated samples. [ABSTRACT FROM AUTHOR]

This paper evaluates the mechanical and thermal properties of 3D-printed short carbon fiber reinforced composites (sCFRPs). A numerical analysis was developed to predict the mechanical and thermal properties of the sCFRPs, which were verified via experimental tests. In the experiments, a novel technique was adopted by coating the sCFRPs with carbon fiber fabric and copper mesh to further improve its mechanical and thermal performance. Various copper meshes (60-mesh, 100-mesh and 150-mesh) were integrated with carbon fiber fabric to form a multilayer structure, which was then coated on the surface of Nylon 12-CF composite material (base material) to form a composite plate. The effects of the copper mesh on the mechanical and thermal properties of the composite plate were studied theoretically and experimentally. The results show that the addition of different copper meshes had a significant influence on the mechanical and thermal properties of the composite plate, which contained carbon fiber fabric, copper mesh and the base material. Among them, the mechanical and thermal properties of the composite plate with the 60-mesh copper mesh were significantly improved, while the improvement effect slowly declined with the increase in the thickness of the base material. The composite plate with 100-mesh and 150-mesh copper meshes had improved mechanical properties, whereas the influence on its thermal conductivity was limited. For thermal conductivity calculation, both the thickness and length directions of the heat transfer were considered. The comparative analysis indicated that the calculated values and experimental results are in excellent agreement, meaning that this numerical model is a useful tool for guiding the design of surface lamination for 3D-printed sCFRPs. [ABSTRACT FROM AUTHOR]

Ceramic coatings are used to protect against high-temperature oxidation of metal products. The efficiency of the technology of detonation spraying of two-layer coatings of aluminum oxide ( Al2O3 ) and a heat-resistant alloy (CoCrAlY) on the surface of a sample made of steel 12X18H10T was studied. A multi-chamber detonation unit was used in the work, providing high speed (up to 1000 m/s) and a 60–80% utilization rate of the sprayed material. We used an oxygen-neutral combustible mixture based on propane-butane. The coating material has a smooth gradient of properties from ceramic to sample substrate The complex of the obtained structural and physical-mechanical properties of the coating material makes it possible to predict its high performance under conditions of high-temperature oxidation.

The paper presents research results of Y–Al–O system-based coatings synthesized by cathodic-arc deposition simultaneously from two electric-arc evaporators with single-component Y and Al cathodes. Three different modes of annealing are used. After the deposition process, the coatings are annealed in a vacuum furnace at 800 and at 1200°C to identify the effect from the annealing temperature on the phase composition. The formation of the YAlO3 phase occurs in all annealing modes. More complex Y3Al5O12 and Y4Al2O9 oxides appear with increasing process temperature. According to the X-ray diffraction analysis, the process temperature and deposition mode affect the phase composition of the coating, which acquires the amorphous structure. The coating structure is studied on a scanning electron microscope. After 1200°C annealing, the coating sublayer diffusion occurs in the base material. [ABSTRACT FROM AUTHOR]

Thin film-composed coatings can significantly improve the mechanical and tribological properties of spacecraft friction units. In this regard, protection by ion-plasma coatings has become one of the most used options and well-established technologies. However, design of coatings that remain effective over multiple usages, is a challenge. Improving their production requires a large number of parameters to be optimized and many verification experiments to be set up. We exploited machine learning algorithm to solve the problem of double layer coatings optimization with respect to a set of mechanical properties (hardness, Young's modulus, Poisson's ratio, and yield stress). The training dataset was constructed using the adaptive sampling algorithm and numerical simulation of indentation in ANSYS for coatings of different compositions and thicknesses. The machine learning approximation provided significant accuracy (R2 > 0.96) in predicting the coating hardness based on the mechanical properties of its individual layers. The feature importance analysis of the Extra Trees algorithm was used to define the parts of the indentation curve that carry information about the properties of individual coating layers. We have also addressed the inverse problem of coatings design in terms of the required hardness. Our findings demonstrate that only tandem approach to the cross-validation task permitted correct estimation of error in the presence of multiple ambiguous solutions. The value of error was smaller than 0.15 GPa. Being comprehensive, the proposed methodology can be applied to design optimal multilayer coatings in terms of their mechanical properties for friction units in aviation and rocketry-astronautics. • Database of numerical nanoindentation experiments for double layered coatings. • Direct problem of predicting coating hardness from layer's parameters was solved. • Extra Trees algorithm has high performance for predicting hardness: R2 score >0.95 • Inverse problem of predicting layer's parameters from coating hardness was solved. • Tandem approach was important during the cross-validation in the inverse problem. [ABSTRACT FROM AUTHOR]

Due to its unique physical and chemical properties, graphene oxide (GO) has excellent potential in energy-saving applications, especially in hydrogen storage materials such as bulk and layer coatings. A three-layer GO/Ni/GO coating was applied successfully on the Ni-foam through the hybrid coating process. GO was firstly synthesized by modified Hummers' method and then deposited on Ni-Foam using an electrophoretic deposition (EPD) method at 40, 60, and 80 V at various times (1 and 2 h). Furthermore, Ni-layer was applied on the first applied to GO layer using a Ni-electroplating bath at 3 V for 3 min. For evaluation of the electrochemical hydrogen storage performance, cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) were carried out in 1 M NaOH solution at room temperature. Obtained results showed a significant improvement in the amount of adsorbed hydrogen. The hydrogen storage capacity was increased from 88 to 741 F. g−1, and load transfer resistance decreased from 260 to 35 Ω for uncoated and coated porous substrates, respectively, which is due to the achieved high specific area. Based on the hydrogen storage capacity, the optimum EPD method is 60 V and 2 h. [Display omitted] • Multi-layer GO coating was achieved successfully by combining EPD and electroplating methods. • Discharge capacity of 741 F/g at current of 3 mA/g was achieved. • 60 V and 2 h were selected as the optimum condition of EPD process. [ABSTRACT FROM AUTHOR]

TiC-Ti3SiC2 gradient hybrid interphase on the surface of SiC fibers was successfully obtained through the molten salt method. The electromagnetic parameters of the prepared samples can be accurately controlled by adjusting the reaction temperature. A significant bimodal effect is observed in electromagnetic parameters patterns, corresponding to the double interface layer. TiC-Ti3SiC2 gradient hybrid interphase plays a dominant role in impedance matching, as well as in the attenuation layer through multi-interfacial polarization and conduction loss. Through the co-evaluation of the suppression of specular reflection and non-specular scattering properties of the samples, the SiC fiber with the TiC-Ti3SiC2 gradient hybrid interphase is expected to be a high temperature resistant radar absorbing material for future stealth aircraft. [ABSTRACT FROM AUTHOR]

In this study, the Cr/Cr-W/W-DLC/DLC multilayer coating was deposited on 5A06 Al alloy using a combination of unbalanced magnetron sputtering system and filter cathode vacuum arc technique. Dry linear reciprocating sliding wear tests were performed to evaluate the tribological properties of the deposited coating at different temperatures from −100 °C to 25 °C. The microstructure, mechanical properties and wear characteristics of the multilayer coating were also characterized by SEM, EDS, nanoindenter and nanoscratch tester, respectively. The results show that, compared with 0 °C and 25 °C, the tribological behavior of the multilayer DLC coating exhibits significant differences at low temperatures. The formation of the transfer layer and the graphitization caused by the flash temperature contribute to explain the excellent tribological performance of the coating at room temperature and 0 °C. The deterioration of the tribological properties of the multilayer coating at subzero temperatures is ascribed to the inhibition of the graphitization process, as well as the oxidation and capillary action of water molecules. Cyclic shear stress and low temperature lead to the formation of microcracks and surface spalling, which also increases the friction coefficient and wear rate of the multilayer DLC coating.

Optical characteristics of germanium telluride (GeTe) thin films in multilayer structures are calculated. A model of a multilayer optical coating with a four-level transmission coefficient is developed. Based on the calculated data, thickness values are determined at which the transmittance change is greatest for 1550-nm modulated optical radiation. Experimental samples coated with antireflection GeTe films are synthesized and their optical transmission characteristics are investigated. Combinations of parameters of the multilayer structures for the implementation of contrast transmittance levels are determined. The results of the study represent the implementation of a multilevel artificial optical synapse for neuromorphic processors.

In this work, a multilayer Chemical Vapour Deposition (CVD) coating over a base tool material is developed, and its performance in cutting tailored hard EN8 steel is investigated. Using atmospheric pressure chemical vapor deposition, the TiN-TiCN-Al2O3-TiN coating is created on the TNMG 160408 base material. During deposition, 900 m-Torr of deposition pressure and 800 °C of temperature are maintained. Energy-dispersive X-ray analysis (EDAX) is used to inspect the coated instrument to ensure the desired chemical composition is present. According to experimental findings, when cutting speed increases, surface roughness and thrust force decrease. When feed rate and depth of cut are adjusted in tandem with cutting speed, tool wear increases as cutting speed increases. ANOVA variance analysis is carried out while taking into account the maximum dependence of temperature, torque, tool wear, surface roughness, thrust force, and cutting speed on feed rate. Chip analysis is performed at varying speeds of 140, 200, and 260 mm/min, increasing the working conditions results in longer continuous chips. Chips with helical and tubular shapes can be created at cutting rates of 200 mm/min and a depth of cut of 1 mm, respectively. [ABSTRACT FROM AUTHOR]

This work illustrates a novel approach for the development of orange multilayer interference coatings with improved angular stability of color while maximizing energy efficiency. The high energy efficiency of these interference coatings is based on thin film interference phenomena, which is achieved by depositing multilayer coatings on the inner side of the glass substrate. These multilayer interference coatings are designed to selectively reflect a narrow spectral band of visible light while being transparent to the rest of the solar spectrum, ensuring minimal loss of module efficiency. In this work, three distinct simulated multilayer interference coatings, such as easy orange (EO), thin orange (TO) and enhanced secondary peak orange (ESPO) are deposited on flat and structured glass substrates, that exhibit high color saturation and low angular dependence. Irrespective of substrate type, all of these coatings exhibit high solar energy transmittance ( τ e ) with an average relative light loss of only 12.1 % after multilayer deposition. Angle dependent reflectance measurements, supported by simulation data show that multilayer interference coatings deposited on structured glass substrates are more angular stable than coatings deposited on flat substrates, regardless of the coating type. For the proof of concept, these multilayer interferential coated structured glass substrates are laminated with mini photovoltaic (PV) modules. In addition, the relative efficiency loss of the colored PV module is found to be only ∼10 % for the ESPO coating on the structured glass substrate, indicating a high percentage of conserved solar energy of ∼90 %. Due to high conservation of energy and improved color stability, the developed orange PV module can significantly promote the architectural integration of solar systems in buildings. [Display omitted] • Orange multilayer interference coatings are developed by simulation and experiment. • Presence of a secondary peak along with reflection peak increases angular stability. • Coatings deposited on structured glass are more angular stable than flat glass. • A high percentage of conserved solar energy ∼90 % is achieved for colored PV module. [ABSTRACT FROM AUTHOR]

The carbon interlayers in the multilayer coatings can improve the load-bearing capacity and oxidation resistance, promote the layer-by-layer wear mechanism, and extend the lifespan of the multilayer coating, which is crucial to improving their tribological properties. To investigate the role of C interlayers in the competitive relationship between tribochemistry and material removal in multilayer coatings, this study comprehensively examines the tribological behavior of single layer MoS 2 and multilayer MoS 2 /C coatings through in-situ tribotests and nanoscratch tests. Key findings reveal that the C interlayers enhance the tribological behavior by reducing the oxidation rate of MoS 2 , improving the load distribution, and delaying the onset of coating failure. Specifically, the single layer MoS 2 coating demonstrated a lifespan of 55,000 cycles, whereas the multilayer MoS 2 /C coating achieved 80,000 cycles, reflecting a 45 % enhancement. The critical load increased from 8 mN to 18 mN, indicating a 125 % improvement in removal resistance. The presence of C layers results in a more stable and enduring tribofilm, which leads to reduced friction and wear. This study underscores the importance of in-situ analysis by combining nanoscratch with Raman mapping to elucidate the complex tribological behavior of coatings. These insights are crucial for designing efficient, wear-resistant, low-friction multilayer coatings for diverse industrial applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Poly-ether-ether-ketone (PEEK) is a polymeric material that is often used in biomedical applications due to its excellent mechanical properties and radiolucency; this material is, in general, biologically inert. In recent decades, thermally sprayed biocompatible coatings have been widely employed in metallic implants to improve the osseointegration process in the human body. Thus, not surprisingly, thermally sprayed biocompatible coatings can be envisaged as an excellent alternative to improve the material's surface properties. However, there is little information in the literature about the deposition of thermally sprayed bioactive coatings on polymeric substrates. In the present study, a titanium dioxide (TiO 2) powder was plasma-sprayed on PEEK substrates acting as a bond coat to further deposition of hydroxyapatite (HA)/bioactive glass multilayered coatings. The design of experiments methodology was employed to produce coatings with tailored properties. A key aspect in this work is how the experiments were carried out to understand the effect of powder features, such as chemical composition, on the deposition of the ceramic coatings on the PEEK substrate. Heating/cooling physical laws were employed to discuss the results obtained. The methodology employed in this work allowed to deposit a multilayered coating with adhesion strength of about 50 MPa on PEEK substrates measured using scratch test. The coatings' structural, morphological, chemical, thermal, and mechanical evaluation was performed using X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, differential scanning calorimetry, and micro indentation test, respectively. In-vitro tests were also performed on these coatings under static simulated conditions. The results show that the PEEK's surface can be successfully functionalized, turning it from showing an inert behavior to displaying bioactivity by applying a HA-based bilayer or multilayered coating. • A multilayered coating of HA:BG/HA/TiO 2 was successfully created on PEEK using APS. • "Normalized power" significantly affects substrate damage and coating formation. • Adhesion of strength of the coatings are in the order of 50 MPa. • Multilayer coating on PEEK substrates provides these later of bioactive behavior. [ABSTRACT FROM AUTHOR]

This study is based on the thermal degradation presented in the multilayer coatings [8YSZ/a- Al2O3]n when subjected to thermal cycles, focusing mainly on the analysis of the mechanical properties before and after these. To determine thermal degradation, the coatings were analyzed by XRD before and after thermal cycling. From these results, the presence of a tetragonal phase and an alpha phase belonging to (8YSZ and Al2O3) respectively was determined before the thermal cycles. After the cycles, show new peaks attributed to 2 important factors, the appearance of a monoclinic and cubic phase belonging to 8YSZ and peaks due to the presence of substrate oxides produced by a delamination of the coating and that decreased in intensity as increase in the bilayers number. Mainly, it was determined for the 70 bilayers coating, which presented the best mechanical properties before the thermal cycles, a decrease of 34.44% and 6.41% for hardness and elasticity modulus respectively, after the thermal cycles. From this research, it was concluded that the coating [8YSZ/a- Al2O3]n with 70 bilayers, presented the highest resistance to thermal wear generated in the coatings.

The paper studies the magnetron sputter-deposited multilayer, multicomponent Al–Si–N/Ni/Al–Si–N coating possessing higher corrosion resistance. Studied are the phase and elemental composition of the coating and its structural layers. It is found that all coating layers have a columnar structure. The structure of the Al–Si–N coating is nanocrystalline, while the structure of the nickel layer is finely crystalline. The X-ray diffraction (XRD) analysis shows that AlN and Si3N4 phases with the hexagonal closed packed crystal structure are present in the Al–Si–N layer, which is confirmed by the XRD patterns obtained on a transmission electron microscope. According to corrosion tests, the corrosion resistance of specimens coated by the Al–Si–N/Ni/Al–Si–N coating, is higher than that of uncoated specimens. [ABSTRACT FROM AUTHOR]

The current study intends to investigate the role of advanced coated tool consisting of TiN/TiAlN multilayer coating as well as cutting environment during the machining of Incoloy 825. Condition of machining (roughing and finishing) and cutting tools (new and worn) have also been evaluated. The coated tool was utilised under environment friendly dry machining, while uncoated tools were used under flood cooling and minimum quantity lubrication (MQL). Cutting temperature and various characteristics of surface integrity including surface roughness, surface morphology, formation of white layer, hardness depth profile and residual stress have been compared under different conditions of machining. Although maximum temperature was recorded with the PVD coated tool under dry environment, the same tool resulted in overall improvement in surface integrity compared to the uncoated tools used for wet machining. According to the general trend, flood cooling was more beneficial than MQL when overall machined surface integrity of Ni-based superalloys was considered. [ABSTRACT FROM AUTHOR]

This work shows the atomic scale deformation behavior of crystalline multilayer coating comprising up to five Cr and Ni layers. A molecular dynamics simulation was conducted to visualize the atomic scale behavior of the multilayer during indentation/unloading and scratch. Normal and shear directional forces were recorded to compare repulsion and friction forces between the multilayer models during the indentation/unloading and scratch simulations. Dislocation lines within the layers were quantified to understand the deformation behavior of each model. Atomic scale deformation and dislocation lines after the indentation and scratch were visualized. Generation and movement of a single dislocation line during the indentation simulation were also visualized within a few picoseconds. The repulsion and friction forces of the five-layer model showed the lowest values among the models. The unloading stiffness of the five-layer model was calculated to be the lowest among the models. The amount of plastic deformation and the wear volume of the one-layer model after the indentation and scratch was calculated to be the highest among the models. The number of dislocation lines of the five-layer model showed an increasing trend during the indentation and scratch. The highest dislocation density of the five-layer model might aid in an enhancement of resistance to the plastic deformation to reduce the wear volume when scratched. [ABSTRACT FROM AUTHOR]

This work is devoted to the study of the formation of nanostructured multilayer coatings (TiZr/Nb)N on the surface of an AISI 321 steel substrate depending on the deposition parameters of the Arc-PVD method. The results of the X-ray diffraction analysis showed the formation of solid solution (TiNb)N and ZrN in the multilayer coatings with an FCC structure, ε-NbN with a hexagonal structure, as well as with a small volume fraction of the ε-Ti2N and β-Nb2N phase. On the basis of phase composition data, it is possible to assume that an increase in the number of bilayers leads to a decrease in the nitrogen concentration in the bilayers and, consequently, to a decrease in the volume fraction of ε-NbN and β-Nb2N nitrides. In all investigated systems obtained at −100 V and −200 V bias potentials, ε-NbN is the main phase. The study of the element distribution over the thickness of the (TiZr/Nb)N coating confirms the results of the X-ray diffraction analysis. The use of the structure model in the form of alternating layers allows for significantly improving the adhesion characteristics of the protective coating, as well as ensuring their high hardness. Based on the experimental results, it is possible to analyze changes in the mechanical and tribological properties of multilayer coatings depending on the number of applied bilayers. The results of the study of the elastic modulus and hardness of multilayer coatings (TiZrNb)N with different numbers of bilayers showed that a large number of bilayers (small thickness of each individual layer) shows the lowest value of hardness. It is assumed that as the bilayer thickness decreases, the coating characteristics are closer to the monolayer alloy than to the multilayer structure. [ABSTRACT FROM AUTHOR]

A TiN/TiNC/Al2O3 multilayer coating was deposited on an Inconel 625 alloy by the chemical vapor deposition method as a protective barrier to improve the corrosion resistance in supercritical water. The corrosion characteristics were evaluated in a reactor at 500 °C and 25 MPa for 72 h. The surface morphology of the coated samples was relatively dense with no obvious cracks or pores observed. The XRD analysis revealed that the coatings were composed of TiN, TiNC and α-Al2O3 phases. After exposure to supercritical water, the surface morphology of the coatings was still dense and kept integrity. The phase composition of the coatings was also not changed, with no obvious corrosion scales detected. This result demonstrates the effectiveness of TiN/TiNC/Al2O3 coatings as a protective coating under harsh supercritical water environments. [ABSTRACT FROM AUTHOR]

A comprehensive experimental investigation of the wear behaviour of coated spur polymer gears made of POM is performed in this study. Three different thicknesses of aluminium (Al) coatings were investigated and deposited by the Physical Vapour Deposition (PVD) process. The Al coating was deposited in three steps: By plasma activation, metallisation of the aluminium by the magnetron sputtering process, and plasma polymerisation. The wear of the gears was tested on an in-house developed testing rig for different torques (16, 20, and 24 Nm) and a rotational speed of 1000 rpm. The duration of the experiments was set to 13 h, when the tooth thickness and, consequently, the wear of the tooth flank were recorded. The experimental results showed that the influence of metallisation with aluminium surface coatings on the wear behaviour of the analysed polymer gear is not significantly important. The results also showed that the gears with a thicker aluminium coating showed greater wear than gears with a thinner coating or even without a coating. This is probably due to the fact that the aluminium particles that started to deviate during gear operation represented the abrasive material, which led to the faster wear of the contacting surfaces of the meshing gear flanks. [ABSTRACT FROM AUTHOR]

The paper presents the results of the study of the influence of thermal fields on the deformation processes occurring in the surface layers of the cutting tool in the cutting zone. The proposed friction model takes into account the structural and phase composition of the coating material, deformation processes in the coating and emerging stresses under the influence of temperature flow in the contact area. The thermodynamic influence on the physical and mechanical characteristics of the coating was studied by the phase plane method through analytical research and construction of phase portraits by numerical integration of the corresponding system of differential equations using the Runge--Kutta algorithm. An analysis of Lyapunov indices for special points of the system was carried out, conclusions were drawn regarding the characteristics of the behavior of the 'dynamic stress-strain' system for tool surfaces with and without coating. [ABSTRACT FROM AUTHOR]

The reliability and durability of devices that operate in vacuum and are subjected to wear are critical issues. The concerns rise at the macroscale wherein the contact area is large, yet the contact stress is in the GPa range. This paper reports on the design and fabrication of a coating comprising nitridized molybdenum disulfide (MoSN) supported by a novel nanolayered coating composed of carbon with subnanometer‐thick periodic albeit discrete Cr interlayers. The MoSN coatings are deposited onto mating surfaces using pulsed‐DC magnetron sputtering in an atmosphere with varying N2 to argon (Ar) ratios. Pulsed‐DC parameters, such as pulse duty and frequency, together with nitrogen content, are systematically optimized to achieve superior mechanical and tribological properties. The results reveal the importance of optimizing pulsing parameters during deposition as they significantly alter the properties of MoS2. The outcome is fabrication of a coating that despite having a low thickness, exhibits extremely low friction and record‐breaking macroscale wear rate in high vacuum compared to the values reported in the literature by date. Lastly, the analysis confirms the prediction of theoretical studies regarding the release of entrapped nitrogen in gaseous form during the wear process without disrupting the formation of a stable solid lubricant tribofilm. [ABSTRACT FROM AUTHOR]

CoCrMo alloy is widely used in artificial orthopedic joint applications due to its high mechanical properties. But, high levels of the metal ion release from alloy surfaces cause variable toxic and allergic effects on the patient in vivo use. This case restricts the lifetime of the implant and results in the failure of the artificial joint. In order to enhance the corrosion resistance and to decrease the metal ion release, alloy surface was multilayer-coated by closed field unbalanced magnetron system. The protective efficiency of the coatings was determined by potentiodynamic polarization tests and static immersion tests were performed for 45, 60 and 90 days in the simulated body fluid in order to understand the effect of the coatings on the metal ion release. The metal ion concentrations in the simulated body fluids were determined by using inductively coupled plasma mass spectrometry device. The electrochemical corrosion results showed that the multilayer coatings provided 93 % protective efficiency in terms of corrosion resistance. Multilayer coatings decreased the metal ions release levels significantly, especially Co leaking was decreased approximately 52 times compared to uncoated samples.

This work were studied the effect of technological parameters of detonation spraying on the phase composition and tribological characteristics on the bases of NiCr and Al2O3 coatings. As well as therewas obtained and investigated multilayer coating on the basesof NiCr/NiCr-Al2O3/Al2O3. It was determined that during detonation spraying the phase composition of Al2O3 coatings strongly depends on the degree of filling the borehole with a gas mixture. The . -Al2O3 -phase content in the coatings increases when the degree of filling is 63% and 54%. Only one CrNi3 phase is observed on the diffractograms and only increase of reflex intensity (020) at barrel filling by 58% is observed by sputtering on the bases of NiCr coatings in different degrees of barrel filling. The results of the coating nanohardness study showed that the hardness of the Al2O3 coating increases depending on the content of . -Al2O3 in it. Al2O3 coating has the maximum nanohardness values and is 16.42 GPa at the borehole is filled to 63%. The nanohardness of NiCr coating has the maximum values at barrel fillingby58% and consisting of 8.02 GPa.

Nickel–Iron coating was formed from a sulfate base electroplating bath under a current density of 3 A/dm 2 and turbulence of 300 rpm on a previously prepared cylindrical steel substrate. In order to obtain a sample including nickel composite coating, different amounts of alumina particle powder were added to the plating solution of the sample in question. By adding different quantities of ferrous sulfate to the electroplating bath under a current density of 2.5 A/dm 2 and turbulence of 300 rpm, an optimal sample containing 20 g/L of ferrous sulfate was obtained was free of any stress and microcracks. A hardness test was performed for the optimal sample among the nickel–iron​ composite samples, and the sample containing 50 g/L of alumina particles was selected as the optimal sample. The Ni–Fe/Al 2O3 composite sample was tested for hardness, corrosion and wear. The obtained results showed that the highest hardness level is equivalent to 740 HV and the best corrosion resistance with the most positive corrosion potential. The lowest amount of wear mass is equal to 0.1 mg, and it showed the highest wear resistance.

The versatility of sol–gel systems makes them ideal for functional coatings in industry. However, existing coatings are either too thin or take too long to cure. To address these issues, this paper proposes using an atmospheric pressure plasma source to fully cure and functionalize thicker sol–gel coatings in a single step. The study explores coating various substrates with sol–gel layers to make them scratch-resistant, antibacterial, and antiadhesive. Microparticles like copper, zinc, or copper flakes are added to achieve antibacterial effects. The sol–gel system can be sprayed on and quickly functionalized on the substrate. The study focuses on introducing and anchoring particles in the sol–gel layer to achieve an excellent antibacterial effect by changing the penetration depth. Overall, this method offers a more efficient and effective approach to sol–gel coatings for industrial applications. In order to achieve a layer thickness of more than 100 µm, the second part of the study proposes a multilayer system comprising 15 to 30 µm thick monolayers that can be modified by introducing fillers (such as TiO2) or scratch-resistant chemicals like titanium isopropoxide. This system also allows for individual plasma functionalization of each sol–gel layer. For instance, the top layer can be introduced with antibacterial particles, while another layer can be enhanced with fillers to increase wear resistance. The study reveals the varying antibacterial effects of spherical particles versus flat flakes and the different scratch hardnesses induced by changes in pH, number of layers, and particle introduction.

• Design of NiAl/Al/Si-NiAl multi-layer coating; • The multi-layer coating exhibits excellent resistance to high-temperature molten chloride salt corrosion; • It offers a promising approach for developing corrosion-resistant Ni-Al coatings. The microstructure and resistance to high-temperatures molten chloride salt corrosion of NiAl/Al/Si-NiAl coating was investigated. The pre-oxidation integrates NiAl/Al/Si-NiAl multilayer coating into a unified structure, resulting in the formation of a continuous dense oxide layer. During corrosion process, the oxide layer initially grows and thickens, then reaches a stable state, and finally becomes thinner. The mass change remained at approximately −2.5 ± 0.2 mg/cm2 after 162 h of corrosion. The structural design of the multi-layer coating further increases the thickness of the Al 2 O 3 layer and strengthens the coating's resistance corrosion. This fully utilizes the role of the pure Al layer as Al source and also takes advantage of Si addition to promote the formation of Al 2 O 3 layer and hinder the diffusion of Cr. [ABSTRACT FROM AUTHOR]

Metal bipolar plate (BPP) is one of the key components in proton exchange membrane fuel cell (PEMFC). However, the high interfacial contact resistance and poor corrosion resistance of BPP remain the great challenges for its commercialization. In this study, multilayer TiN/TiCN coatings were designed, and multi-arc ion plated on AISI 316L stainless steel used for BPP in PEMFC. Effects of gas pressure on the microstructure and properties of multilayer TiN/TiCN coatings were evaluated. The results show that microstructures of the multilayer TiN/TiCN coatings are dense with nanocrystalline grains. Gas pressure has no big influence on the thickness of coatings, which is about 2 μm in the present investigation conditions. The multilayer TiN/TiCN nanocrystalline coatings are shown in good corrosion resistances in the simulated solution of PEMFC, especially for the one obtained under 1.0 Pa, which achieves the best corrosion resistance. The interfacial contact resistances of the multilayer TiN/TiCN nanocrystalline coatings are decreased evidently, which can be decreased to as low as 1.82 mΩ cm2 at 1.4 MPa for the one obtained under 1.0 Pa. The present findings offer a substantial support for the commercial viability of BPP coated with the multilayer TiN/TiCN nanocrystalline coating. • Nanocrystalline multilayer coatings with alternating TiN and TiCN layer prepared by multi-arc ion plating. • TiN/TiCN multilayer coating possesses a good corrosion resistance in the simulated solution of PEMFC. • TiN/TiCN multilayer coating shows the lower interfacial contact resistance than that of the untreated stainless steel. [ABSTRACT FROM AUTHOR]

Hybrid concentrated solar power/photovoltaic systems (CSP/PV) combine the advantages of the two separate systems while reducing their drawbacks. The design of such a hybrid system is challenging due to the various trade-offs between the thermal and electrical performance, and the overall system complexity. A reliable simulation model that includes all relevant optical, thermal, and photovoltaic aspects, can therefore be extremely useful to analyse the combined system performance and fine-tune the various design parameters. While multi-physics modelling of photovoltaic systems is well established, this is not the case for hybrid CSP/PV. In this paper, a novel multi-physics framework is presented for a hybrid system consisting of a parabolic trough with integrated PV cells covered by a dichroic coating, focusing incident sunlight towards a thermal receiver. Instead of monofacial PV cells, bifacial cells are considered for harvesting also the diffuse and ground reflected light at the back of the trough. The presented framework relies on an existing simulation tool for PV modules, that is combined with a ray-tracer that includes the spectral beam splitting functionality of the coating, and a novel 1.5D thermal model for the receiver tube. Long term outdoor monitoring results are used to predict the averaged, time-resolved annular thermal and electric energy yield of the system. This energy production is compared for three different multilayer coating designs with an increasing amount of (TiO 2 , SiO 2) layers. These results show that the amount of reflected sunlight towards the thermal receiver can be enhanced at the expense of the transmitted sunlight towards the PV cells, when a higher number of layers are used. The reduction of the incident power on the PV cells is however almost fully compensated by the enhanced spectral match of the transmitted light with the spectral response of the considered bifacial cells, in addition to the enhanced cell efficiency due to the lower thermalization losses. This results in superior system efficiency, for the application scenario where the generated thermal energy is also converted in electrical energy, and geographical locations with sufficient direct sunlight; a conclusion that is drawn from comparing the total electrical energy yield in Spain and Belgium, as a function of the thermal to electrical conversion fraction. [Display omitted] • Demonstration of a novel multi-physics simulation framework for hybrid CSP/PV systems. • Integration of long-term monitoring results allows predictive energy yield modelling. • Usage of bifacial PV cells enhances CSP/PV system efficiency for diffuse sunlight. • Number of layers in spectral beam splitter has crucial impact on system performance. • Geographical location determines potential application scenarios of hybrid CSP/PV. [ABSTRACT FROM AUTHOR]

Here, we report the development of high corrosion-resistant (Ni-Fe) alloy coatings from a low-concentration bath through multilayer approach. The corrosion analysis of (Ni-Fe) alloys electrodeposited at different current densities (2.0–5.0 A/dm2) revealed that the coating developed at 2.0 A/dm2, represented as (Ni-Fe)2.0 A/dm2 is highly anticorrosive. The corrosion resistance of monolayer (Ni-Fe)2.0 A/dm2 coating, showing a corrosion rate of 14.71 × 10−2 mm/y was further improved by utilizing multilayer approach. Corrosion study revealed that multilayer coating having 120 layers, represented as (Ni-Fe)2.0/4.0/120 was six times more anticorrosive (with corrosion rate = 2.33 × 10−2 mm/y), compared to its monolayer counterpart. The improved anticorrosion performance of multilayered coatings was explained in the light of advanced instrumental techniques. [ABSTRACT FROM AUTHOR]