Coat Layer Research Articles

Significant Differences in Structure and Properties of Cast Film Prepared by Solution Casting and Coat Layer Prepared by Solution Coating of Block Copolymer Adhesives

ABSTRACTThis study reports significant differences in the structures and properties of test specimens of block copolymer adhesives prepared according to two different methods, solution casting and solution coating. To evaluate the mechanical properties of a pressure‐sensitive adhesive (PSA), test pieces are generally prepared by solution casting (solvent evaporation). Thus, the obtained specimen is completely different from the PSA layer of an actual PSA tape, which is commonly prepared by solution coating. This concept of equivalence of the two PSA test pieces is commonly adopted by engineers in PSA production companies, and violation of this concept may critically affect their research and development activities. In this current study, it was found that the surface segregation of the tackifier influenced the viscoelastic behavior of cast films, and the peak‐top temperature of the loss tangent (tan δ) was lower than that of the corresponding coat layer. Additionally, conditions were derived experimentally for the commonly used solution casting, by which mechanical properties equivalent to those of the test piece prepared by solution coating were accidentally obtained. This outcome of the current study can greatly contribute to the community of the PSA industries.

In Situ Bulk Oxygen Vacancy Manufacturing and Surface Spinel Layer Coating Enable High‐Performance Na‐Ion Layered Fe–Mn Based Cathodes

AbstractIron‐manganese based layered transition metal (TM) oxides are promising cathodes for sodium‐ion batteries owing to their high specific capacity and cost effectiveness, but they are confronted by severe Mn3+ Jahn‐Teller distortion, lattice oxygen loss, and irreversible Fe migration. Herein, in situ bulk oxygen vacancy manufacturing and surface spinel (MnFe2O4) layer coating for the P2‐Na0.67Fe0.3Mn0.7O2 (NFM(OV)+MnFe2O4) cathode are realized via an argon‐atmosphere calcination method. The bulk oxygen vacancies improve the Mn redox capacity by reducing Mn valence, and favor the reversible Fe interlayer migration to enhance oxygen redox activity through the Na─O─(TM vacancy) configurations. The migrated Fe ions to Na sites can serve as “temporary pillars” to suppress the TMO2 layers gliding in the deep charged state and return to their original positions upon discharge. The spinel coating layer can mitigate the lattice oxygen escape, prevent the interfacial side reactions, and alleviate the Mn3+ Jahn‐Teller distortion. Therefore, the tailored NFM(OV)+MnFe2O4 cathode affords high discharge capacities (185.7 and 84 mAh g−1 at 0.1 and 5 C, respectively) and desirable cycling stability (82.6% capacity retention after 300 cycles). This study paves the way for fabricating high‐performance Fe─Mn based layered oxide cathodes by simultaneously tuning the bulk and surface structures.

High-Temperature Oxidation Behavior of TiN-, Cr-, and TiN–Cr PVD-Coated Zircaloy 4 Alloy at 1200 °C

Zirconium alloys are essential materials for nuclear fuel cladding. During a loss-of-coolant accident (LOCA), zirconium alloy cladding can oxidize in high-temperature steam (>1000 °C), generating hydrogen and releasing significant heat. Without timely emergency actions, this can result in hydrogen explosions or nuclear leakage. In this study, titanium nitride (TiN), chromium (Cr), and TiN–Cr composite coatings were deposited on the surface of Zr-4 alloy using the magnetron sputtering method. The coatings’ surface and cross-sectional morphologies were examined using scanning electron microscopy (SEM), and their phase structures were analyzed with X-ray diffraction (XRD). The mechanical properties were evaluated using scratch tests, and their resistance to high-temperature steam oxidation was tested in a tube furnace connected to a steam generator. The results showed that the TiN, Cr, and TiN–Cr coatings exhibited strong adhesion to the Zr-4 substrates, with distinct interfaces and pure phase structures. After high-temperature steam oxidation, cracks appeared on the surfaces of the TiN, Cr, and TiN–Cr coatings, likely due to differences in the thermal expansion coefficients of TiO2, Cr2O3, and residual Cr layers. These cracks created pathways for the oxidizing medium, potentially leading to the oxidation of the substrate or inner layers of the composite coatings. For the Cr and TiN–Cr coatings, despite cracking of the Cr layer and melting of the TiN layer at high temperatures, the residual Cr layer effectively restricted oxygen diffusion into the Zr-4 substrate. This study suggests that layers with low melting points, such as TiN, are unsuitable for composite coatings in high-temperature applications. However, adding a Cr layer on top of the TiN layer to form a TiN–Cr composite coating improves adhesion between the coating and the substrate. The TiN–Cr composite coating functions as an effective diffusion barrier at temperatures up to 1200 °C, comparable to a pure Cr coating.

Broadband and omnidirectional antireflective coatings with gradient refractive index prepared using chitin nanofibers and pore generation agent.

Broadband and omnidirectional antireflective coatings with gradient refractive index prepared using chitin nanofibers and pore generation agent.

Mo Doping and Dual-Conductive Layer Coatings to Mitigate Structural Degradation and Extend Service Life for Ni-Rich Layered Cathode Oxides

Mo Doping and Dual-Conductive Layer Coatings to Mitigate Structural Degradation and Extend Service Life for Ni-Rich Layered Cathode Oxides

Correction to “Robust Nitrogen/Sulfur Co‐Doped Carbon Frameworks as Multifunctional Coating Layer on Si Anodes Toward Superior Lithium Storage”

Correction to “Robust Nitrogen/Sulfur Co‐Doped Carbon Frameworks as Multifunctional Coating Layer on Si Anodes Toward Superior Lithium Storage”

Compression of Semibounded Body with Thin Coating Layer Along Interface Near Surface Crack. Part II

Compression of Semibounded Body with Thin Coating Layer Along Interface Near Surface Crack. Part II

Oxidation Resistance of NiCrAl with CeO2 Addition for Thermal Barrier Coating System

Abstract The thermal barrier coating (TBC) system, including a bond coat and a top coat, was developed to enhance the service life of components functioning at elevated temperatures in gas turbines. Research on the bond coat layer for the creation of high-temperature resistance materials includes the addition of 0.4 wt.% CeO2 into the NiCrAl layer was conducted. The assessment of NiCrAl and NiCrAlCe is conducted to evaluate the performance of the bond coat layer. These coating materials were produced using mechanical milling. High-velocity oxygen fuel (HVOF) was used to apply the metallic layer onto the Inconel 625 substrate. A zirconia ceramic layer stabilized with 8 mol% yttria (8YSZ) was subsequently placed to the metal binder layer via air plasma spraying (APS). The coated samples underwent oxidation testing under equilibrium conditions at 1000 °C for 100 hours. The microstructure and phases present in the coating layer were analyzed utilizing field-emission scanning electron microscopy (FE-SEM) and x-ray diffraction (XRD). The findings indicate that TBC with NiCrAlCe bond coat exhibited superior oxidation resistance. Adding CeO2 as an active-controlled element significantly enhanced the growth of protective oxides after coating, which led to a reduction in layer porosity. The oxidation kinetic showed a parabolic curve, characterized by minimum mass change and oxidation rate of 0.9751 mg/cm2 and 2.64 × 10−12 g2/cm4s, respectively. Moreover, the t’-ZrO2 phase in NiCrAlCe-8YSZ possesses better thermal stability than NiCrAl-8YSZ, attributed to its consistent crystallite size and microstrain under thermal exposure.

Effect of Sintering Temperature on Adhesion Strength of Hydroxyapatite Coating Layer of Titanium TNTZ Prepared by Dip Coating Method

Effect of Sintering Temperature on Adhesion Strength of Hydroxyapatite Coating Layer of Titanium TNTZ Prepared by Dip Coating Method

Antiprotein Corona-Fouling Effect of the Double-Stranded DNA Coating Layer on the Gold Nanoparticles-Small Molecule Adsorbent Probe.

The formation of a protein corona (PC) can significantly impact the detection ability of gold nanoparticles (AuNPs)-small molecule adsorbent probes based on competitive adsorption. To alleviate this problem, in this study, double-stranded DNA (dsDNA) was introduced to modify the AuNP probes to mitigate the negative effect of PCs on the detection of small molecules by taking the AuNPs-dichlorofluorescein (DCF) probe-based detection of ambroxol hydrochloride (AMB) as a study model. It was found that based on the dsDNA-modified AuNPs-DCF probe (dsDNA@AuNPs-DCF), the accuracy for the detection of AMB was significantly improved, which might be attributed to the isolation of proteins from the surface of AuNPs while still allowing small molecules to access the surface due to the introduction of rigid dsDNA. Further, the effect of the strand length and the number of dsDNA modified on the surface of AuNPs on the antifouling performance was then investigated, and it was found that the LOD value of AMB in artificial milk samples by dsDNA10bp90@AuNPs-DCF probes (with 10 base strand length and 90:1 ratio of dsDNA to AuNPs) is decreased more than 2-fold compared with that by the AuNPs-DCF probe. Moreover, based on dsDNA10bp90@AuNPs-DCF probes, the recovery rates of AMB analyzed in commercial milk samples greatly improved compared with that with the AuNPs-DCF probe, particularly when the samples contained AMB with much lower concentrations. This study demonstrates a dsDNA-based antiprotein corona-fouling strategy for the AuNPs-small molecule adsorbent probe, which provides beneficial ideas for dealing with the interference resulting from PCs to the studying of biological samples.

Novel Anchored Branched Polymer Coating Layers for Enhanced Redox Kinetics in Aqueous Zinc‐Ion Batteries

The fundamental issues associated with Zn anodes prevent the commercialization of aqueous Zn ion batteries. To address this, a simple dip‐coating method was used to coordinate a thin layer of branched polyethyleneimine (b‐PEI) polymer onto the electrode surface. This process increases hydrophilicity and reduces interfacial resistance between the electrode and aqueous electrolyte. Consequently, electrolyte leaching from the hydrophilic polymer coating layer is prevented, charge distribution is uniform, and stable electrochemical performance is maintained over extended periods. In symmetric cell testing, the b‐PEI@Zn anode exhibits a lifespan of over 1400 h (3 mA cm−2, 1 mAh cm−2). Furthermore, full‐cell tests, the b‐PEI@Zn anode demonstrates higher capacity (+26.05%) and improved stability (95.4%) compared to the bare Zn anode (0.5 A g−1). This study presents a practical surface modification strategy for Zn anodes and underscores the potential of innovative polymer‐based electrode coatings for aqueous battery applications.

Compression of Semibounded Body with Thin Coating Layer Along Interface Near-Surface Crack. Part I

Compression of Semibounded Body with Thin Coating Layer Along Interface Near-Surface Crack. Part I

Experimental Studies of the Effects of Recoating on Fire Protection Properties of Old and New Layers of Intumescent Coatings for Steel Elements

ABSTRACTThis paper presents the results of experimental studies investigating the effects of recoating on fire protection properties of composite layers of intumescent coatings for steel elements. Intumescent coatings, both with and without topcoats, were applied to steel plates. The samples were subjected to different cycles of hydrothermal aging before recoating. The composite layers of the existing and new coatings were then tested under fire. Comparisons of the morphological structures of the carbonaceous char revealed that the existing coating had little effect on the expansion properties of the new coating. However, the new coating reduced the expansion ratio of the existing coating. The thermal resistance of the existing coating decreased with the increasing thickness of the new coating. For specimens with a new coating 1.0 mm thick, the thermal resistance of the existing coating, after even moderate environmental exposure, was < 20% of the total and can be ignored. Contributions from the existing coating may be considered when specifying the thickness of the new coating if the new coating thickness is small and the existing coating is subjected to moderate environmental aging. Recoating with a different type of intumescent coating from the existing one appeared to provide better fire protection performance than using the same type.

Application of Machine Learning in Terahertz-Based Nondestructive Testing of Thermal Barrier Coatings with High-Temperature Growth Stresses

The gradual growth of oxides inside thermal barrier coatings is a key factor leading to the degradation of thermal barrier coating performance until its failure, and accurate monitoring of the growth stress during this process is crucial to ensure the long-term stable operation of engines. In this study, terahertz time-domain spectroscopy was introduced as a new method to characterize the growth stress in thermal barrier coatings. By combining metallographic analysis and scanning electron microscope (SEM) observation techniques, the real microstructure of the oxide layer was obtained, and an accurate simulation model of the oxide growth was constructed on this basis. The elastic solutions of the thermally grown oxide layer of thermal insulation coatings were obtained by using the controlling equations in the rate-independent theoretical model, and the influence of the thickness of the thermally grown oxide (TGO) layer on the stress distribution was explored. Based on experimental data, multidimensional 3D numerical models of thermal barrier coatings with different TGO thicknesses were constructed, and the terahertz time-domain responses of oxide coatings with different thicknesses were simulated using the time-domain finite difference method to simulate the actual inspection scenarios. During the simulation process, white noise with signal-to-noise ratios of 10 dB to 20 dB was embedded to approximate the actual detection environment. After adding the noise, wavelet transform (WT) was used to reduce the noise in the data. The results showed that the wavelet transform had excellent noise reduction performance. For the problems due to the large data volume and small sample data after noise reduction, local linear embedding (LLE) and kernel-based extreme learning machine (KELM) were used, respectively, and the kernel function was optimized using the gray wolf optimization (GWO) algorithm to improve the model’s immunity to interference. Experimental validation showed that the proposed LLE-GWO-KELM hybrid model performed well in predicting the TGO growth stress of thermal insulation coatings. In this study, a novel, efficient, nondestructive, online, and high-precision measurement method for the growth in TGO stress of thermal barrier coatings was developed, which provides reliable technical support for evaluating the service life of thermal barrier coatings.

Solution Deposition Planarization as an Alternative to Electro-Mechanical Polishing for HTS Coated-Conducters

Mechanically flexible substrates are increasingly utilized in electronics and advanced energy technologies like solar cells and high-temperature superconducting coated conductors (HTS-CCs). These substrates offer advantages, such as large surface areas and reduced manufacturing costs through reel-to-reel processing, but often lack the surface smoothness needed for optimal performance. For HTS-CCs, specific orientation and high crystalline quality are essential, requiring buffer layers to prepare the amorphous substrate for superconductor deposition. Techniques, such as mechanical polishing, electropolishing, and chemical-mechanical polishing, can help achieve an optimally levelled surface suitable for the subsequent steps of sputtering and ion-beam-assisted deposition (IBAD) necessary for texturing. This review examines Solution Deposition Planarization (SDP) as a cost-effective alternative to traditional electro-mechanical polishing for HTS coated conductors. SDP achieves surface roughness levels below 1 nm through multiple oxide layer coatings, offering reduced production costs. Comparative studies demonstrate planarization efficiencies of up to 20%. Ongoing research aims to enhance SDP’s efficiency for industrial applications in CC production.

Cold Plasma as a Novel Pretreatment to Improve the Drying Kinetics and Quality of Green Peas

Green peas, with their high moisture content, require effective drying techniques to extend shelf life while preserving quality. Traditional drying methods face challenges due to the dense structure of the seed coat and wax layer, which limits moisture migration. This study investigates cold plasma (CP) pretreatment as a novel approach to enhance drying kinetics and maintain the quality attributes of green peas. The results showed that CP treatment significantly improves drying efficiency by modifying the pea epidermis microstructure, reducing drying time by up to 18.18%. The moisture effective diffusivity coefficients (Deff) for untreated and CP-pretreated green peas were calculated to range from 5.9629 to 9.9172 × 10−10 m2·s−1, with CP pretreatment increasing Deff by up to 66.31% compared to the untreated group. Optimal CP parameters (90 s, 750 Hz frequency, 70% duty cycle) were found to improve the rehydration ratio, preserve color, and increase total phenolic content (TPC) by 24.06%, while enhancing antioxidant activity by 29.64%. Microstructural changes, including pore formation and increased surface roughness, as observed through scanning electron microscopy (SEM), partially explain the enhanced moisture diffusion, improved rehydration, and alterations in nutrient content. These findings underscore the potential of CP technology as a non-thermal, eco-friendly pretreatment for drying agricultural products, with broad applications in food preservation and quality enhancement.

Coating Structure and Corrosion Mechanism of Zn-19%Al-6%Mg Alloy Coating Layer

Coating Structure and Corrosion Mechanism of Zn-19%Al-6%Mg Alloy Coating Layer

EFFECT OF VARYING THE PULSE-PLASMA TREATMENT DISTANCE ON THE PROPERTIES OF CR3C2-NICR DETONATION COATINGS

One of the most promising methods to improve the operational properties and increase the service life of products is the application of functional coatings using various sputtering technologies. Considering the high resistance to wear and corrosion of Cr3C2-NiCr metal-ceramic composition, such coatings have started to be actively used to protect steel elements in hot parts of boilers designed for waste incineration, as well as in electric furnaces and equipment operating on natural gas.This study examines the effect of pulse-plasma treatment distance on the structural characteristics of the surface layer of Cr3C2-NiCr detonation coatings. We study a process involving the deposition of such coatings using a detonation device and then their treatment by pulse plasma. The results show that after such treatment, melting and levelling of the structural components of the coatings occurs without leading to their destruction by the plasma pulses. The microstructure of the coatings is a molten Cr3C2-NiCr based metal-ceramic material. After pulse plasma treatment, Cr2O3 chromium oxide phases are found on the surface, the intensity of Cr3C2 peaks increases and new Cr3C2 reflections appear, indicating an increase in the Cr3C2 phase content. It is also observed that the microstructure becomes more homogeneous after this treatment, which leads to the densification of the Cr3C2-NiCr-based detonation coating.

Buckling Resistance and Its Effect on the Gas Barrier of Composite Coating Layers Based on Polyvinyl Alcohol and Montmorillonite

In addition to the mechanical properties and barrier performance, one of the key properties of flexible films used in food packaging is the resistance of their gas barrier layer to buckling and bending. Testing the gas barrier before and after mechanical stress is time-consuming and resource-intensive, but important to assure a certain gas barrier during the whole life time of the package until food consumption. The aim of this study was, on the one hand, to identify the most significant influencing factors of a composite lacquer formulation and coating on its buckling resistance and, on the other hand, to show a fast and efficient method to identify defects occurring during buckling. The influence of mechanical stress was simulated via Gelbo-Flex treatment, and the samples were examined and evaluated before and after using light microscopy. The evaluation was verified with scanning electron microscopy (SEM) and helium barrier measurement. Polyethylene terephthalate (PET) and polyethylene (PE) films were coated with composite barrier lacquers made of polyvinyl alcohol (PVA) and montmorillonite (MMT) and the wet coating layer thickness (20;40;80;130m) and the composition of the coating were changed. It was found that thin coatings are more resistant to buckling than thick coatings. It was also shown that a higher proportion of MMT in the coating layer leads to a better gas barrier, but poorer buckling resistance. Additionally, it was found that soft PE films are already subjected to high stresses during the coating process, which means that barrier coatings do not build up ideally. However, the barrier-coated soft film withstood mechanical stress better and lost less barrier by a lower factor than the counterpart on the basis of PET. To conclude, the evaluation of the buckling resistance with microscopy offers an efficient method during lacquer development; however, the final decision on the right lacquer composition is dependent on many factors.

Controllable SiOx Coating Layer Promotes High Stable Si Anode for Lithium-Ion Batteries.

Silicon (Si) is considered as one of the most promising candidates for next-generation lithium-ion batteries with high energy density. The main problems are the severe volume expansion and continuous interfacial side reaction of Si that hinder its further application. It can be an effective way by constructing a robust coating layer outside of Si to impede/alleviate the above effect. SiOx with high mechanical strength can largely promote the electrochemical performance of Si. Herein, Si@SiOx material with high specific surface area, high porosity, and controllable coating was synthesized via a simple solid-liquid reaction by LiOH solution etching effect. The etching/oxidation mechanism of Si under alkaline conditions was thoroughly investigated. The surface oxide layer of Si was beneficial to the formation of a solid electrolyte interphase (SEI) with excellent stability and high Li+ conductivity, while its high-porosity structure reduces the volume expansion of the material by approximately 110%. Under the synergistic effect of etching-oxidation, the modified material exhibited superior electrochemical properties. When employed as anode materials, the specific capacity was as high as 3101.5 mAh g-1 and maintained at 841.0 mAh g-1 after 500 cycles at 1 A g-1.