Protective Layer Research Articles

Microcrystalline and nanocrystalline structure of diamond films grown by MPCVD with nitrogen additions: Study of transitional synthesis conditions

This research explores the complex influence of nitrogen concentration and substrate temperature on the resultant properties of polycrystalline diamond (PCD) films grown by microwave plasma chemical vapor deposition (CVD). In particular, we investigated the growth parameters to find the exact conditions for changing the morphology of the resulting film from microcrystalline (MCD) to nanocrystalline (NCD). A series of 2 µm-thick polycrystalline diamond films was grown on Si substrates in methane-hydrogen–nitrogen gas mixtures with varied: (i) nitrogen concentration (0–2 %) and (ii) substrate temperature (700–1050 °C). Comprehensive characterization techniques, including scanning electron microscopy (SEM), micro-Raman spectroscopy, and X-ray diffraction, were employed to assess the morphological, structural, and spectroscopic properties of the films. The study reveals that even minor additions of nitrogen significantly modulate secondary nucleation, impacting both film morphology and phase composition. Furthermore, substrate temperature emerges as another critical parameter, influencing the growth kinetics and crystallite size. The comparison of the characteristics of grown PCD films allowed us to find conditions for the formation of NCD films with minimal surface roughness and maximal growth rate: nitrogen concentration [N2] ≈ 0.2–0.5 % and temperature T ≈ 850–900 °C. These findings can be used to optimize the CVD synthesis parameters of PCD films for applications as protective or friction-reducing layers, as well as for superhard cutting tools and optical devices.

Fractographic investigation of carbon/epoxy PRSEUS composites exposed to flame after compressive failure

After a structural-related composite aircraft crash, a fractographic forensic analysis of the damaged surfaces is typically performed to assess the root causes of mechanical failures. Such accident reconstruction efforts, however, can be impeded if the aircraft catches on fire on the ground (i.e., a post-crash fire occurs), where flames or heat exposure can obscure or destroy the fracture surface morphologies of the fibers (i.e., the primary load carrying constituent). In this study, carbon/epoxy Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) skin-stringer assemblies were subjected to uniaxial compression and subsequently exposed to direct flame using a Bunsen burner. Specimens were oriented parallel, orthogonal, and at 45° to the flame axis for durations of 60 s. Additional vertical burn tests were performed for durations up to 300 s. Fractographic inspection of the failure surfaces before and after flame exposure was performed using a combination of destructive sectioning and scanning electron microscopy. The warp-knitted skin (fascia) surrounding the pultruded rod effectively served as a thermal protection layer, which shielded the rod’s broken filaments from significant thermal degradation and facilitated the identification of microbuckling and other mechanical failure mechanisms. This suggests that the presence of fascia, bulkheads, ribs, skins, and other intermediate layers in aircraft structures may significantly shield underlying principal structural element failure surfaces from fire exposure, facilitating post-crash forensic assessments of composite aircraft. Additionally, the through-thickness VectranTM stitching remained intact even after extended flame exposure, suggesting that such stitching can enhance the fire resistance of composite structures.

Model test investigation on heat and deformation behaviors of canal slopes with protective layers caused by freeze-thaw action

Frost damage is one of the main factors affecting the stability of canal slopes in cold regions. To alleviate the damage, laying protective layers during the construction process has become an indispensable measure. In this study, two slope models were constructed using polyester geotextiles (slope I) and composite geomembranes (slope II) as the protective layer. Additionally, the insulation board in the control group were laid on specific section to examine their anti-frost effect. The temperature, frozen depth, and frost deformations of slope models during the freeze-thaw process were recorded and analyzed. Results suggest that the temperature of slope II is relatively lower than that of slope I in the freezing process. The temperature reduction at all monitoring sections of slope II are larger than that of slope I. The slope I exhibits a significant decrease in maximum frozen depth and maximum frost deformation. In particular, the section with the maximum frost deformation is independent of the type of protective layer, which all occurs in the middle of the slopes. The maximum frost deformations of slope models are 33.60 mm and 37.69 mm, respectively after laying the polyester geotextiles and composite geomembranes. Therefore, the polyester geotextiles have more advantages in reducing frost deformation than composite geomembranes. Additionally, if the insulation board and polyester geotextiles are laid together inside the slope, the maximum frost deformation can be further reduced to 9.72 mm. This study will help in the design and construction of canal slopes in cold regions.

Cancelable palmprint: intelligent framework toward secure and privacy-aware recognition system

Cancelable template protection techniques are indispensable to provide essential security and privacy privileges in biometric systems. This paper introduces an efficient cancelable palmprint recognition technique based on multi-level transformations. Gabor filtering with feature remapping is introduced for extracting highly discriminative features. Histogram remapping is applied to nonlinearly transform the downsampled Gabor features to be normally distributed. This feature-remapping step is proposed to enhance the discriminatory power and alleviate the effect of feature variability and image artifacts. Comb filtering is applied to the mapped features as a first protection layer. To provide security guarantees against linkability attacks, index-based locality-sensitive hashing (LSH) is introduced as a second protection layer to transform the comb-filtered mapped real-valued features into maximum-ranked indices. Recognition is performed in the secured domain to accelerate matching and to preserve the user’s privacy. Results show that the proposed scheme provides a large re-issuance ability, protects templates from being inverted, and demonstrates strong unlinkability across different databases. In addition, favorable verification/identification accuracy is obtained and the system satisfies the needs for real-time applications. A global measure D↔sys\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${D}_{\\leftrightarrow }^{sys}$$\\end{document} value of 0.01 is obtained, and thus, correlation attacks are mitigated. The recognition results for the legitimate scenario are 100% identification accuracy and 0% EER. For the worst case (same token scenario), the corresponding results are 99.752% and 0.31%, respectively.

Enhanced oxidation resistance in nano-lamellar CoCrFeNiNbx (0.45 ≤ x ≤ 0.55) eutectic high entropy alloy during cyclic oxidation at 700–1100 °C

We report the superior oxidation resistance of nano-lamellar CoCrFeNiNbx (x = 0.45, 0.50, 0.55 atom ratio) eutectic high entropy alloy (EHEA) at 700–1100 °C. The as-cast microstructure comprises of nano-lamellar eutectic FCC+Laves phases. The oxidation kinetics followed the parabolic rate in between 700–800 °C, whereas, near-parabolic kinetics is followed at 900 °C. The addition of Nb improves the oxidation and spallation resistance of the EHEAs. A protective outer-oxide layer containing Cr2O3, FeCr2O4-type spinels, whereas, an inner-oxide layer containing Nb2O5, CrNbO4 were formed during oxidation. The mechanism of protection and the superiority of EHEAs as high temperature alloy are explored.

Solanum tuberosum leaf extract as an eco-friendly corrosion inhibitor for Q235-steel in HCl medium: Experimental and theoretical evaluation

Solanum tuberosum leaf extract (STLs), used as a biodegradable corrosion inhibitor, was prepared to mitigate the corrosion rate of Q235 steel in HCl medium. The active inhibitory components existing in STLs were tracked by Fourier transform infrared spectroscopy. Electrochemical measurements, morphological characterization and contact angle tests were combined to evaluate the anti-corrosion performance of STLs at various concentrations and different temperatures, and the results show that the addition of STLs can evidently magnify the charge transfer resistance, expand the double layer capacitance at electric/solution interface, and simultaneously reduce the corrosion current density of Q235 steel in HCl medium with the maximum inhibition efficiency of 91.89 %. The adsorption behavior of STLs on steel was investigated using X-ray photoelectron spectroscopy and adsorption models. It is revealed that the molecules of STLs spontaneously bind to the substrate through chemical and physical action, forming a protective layer to block the diffusion pathway of harsh ions. Furthermore, theoretical calculations confirm that Solanum tuberosum leaves components were adsorbed on steel substrates through donor-acceptor interactions.

Synthesis, structural characterization, thermal analysis and anticorrosion properties of novel AZO-based imidazo[1,2-a]pyridine derivatives: Experimental study and theoretical approaches

In this study, innovative AZO-based imidazo[1,2-a]pyridine derivatives were synthesized using simple and efficient synthetic approach enabling large-scale production. Thermal analysis highlights their suitability for potential applications requiring resistance to moderate temperatures. These compounds were investigated as corrosion inhibitors for MS in a 1 M HCl-medium. Corrosion inhibition studies, including weight loss, PotentioDynamic polarization and electrochemical impedance spectroscopy methods, revealed that AZOs exhibited maximum corrosion inhibition efficiencies reaching 96.13 % and 94.07 %, respectively, at a concentration of 10−3 M and a temperature of 298 K, with both compounds acting as mixed-type inhibitors. The study also delved into the influence of temperature and immersion time on inhibitory performance, revealing stable inhibition within the temperature range of 298–328 K. The calculated standard free energy of adsorption was −42.06 and −40.62 kJ/mol for AZO 1 and AZO 2, respectively, suggesting mixed-type adsorption, with adsorption behavior following the Langmuir isotherm. Morphological analysis through SEM and AFM, showed a reduction in surface roughness in the presence of the inhibitors, while water contact angle measurements indicated a significant increase in surface hydrophobicity. UV–visible and FT-IR analyses confirmed the interaction of AZOs with the MS surface, suggesting the formation of a protective layer composed of adsorbed AZO molecules. Furthermore, computational investigations employing DFT, Monte Carlo, and Molecular Dynamic simulation revealed the formation of coordinate bonds between the studied inhibitors and the metal surface, confirming adsorption on the metallic surface. These findings align well with experimental outcomes, and a possible corrosion inhibition mechanism process was discussed.

Enhanced X-ray shielding efficiency and visible light degradation performance of a multilayer composite protective material

To mitigate the adverse effects of high-energy radiation, such as X-rays, on patients during medical procedures, a multifunctional composite nanofibrous membrane has been engineered to shield against low-energy X-rays. This study involves integrating processed oil-tea camellia shells (OCS) powder into molten polylactic acid (PLA) for modification. Concurrently, metallic Bi is introduced to enhance Bi2WO6, which is subsequently combined with modified PLA and electrospun into nanofibrous membranes for photocatalytic antimicrobial and organic pollutant degradation. Additionally, sodium hyaluronate (NaHA) and a silver nanoparticle solution are electrospun with PLA to form a skin-friendly protective layer. Following this, a chitosan (CS) solution containing WO3 and B4C is used as a coating on the multilayered membranes. The membranes are then freeze-dried to create sandwich-structured multilayer composite protective material. This method addresses challenges associated with polylactic acid (PLA) in electrospinning and alleviates limitations such as low light absorption and slow charge transfer in Bi2WO6. Compared to similar materials, this composite material is lightweight, flexible for cutting, and exhibits strong X-ray shielding capabilities. The composite nanofibrous membrane demonstrates a shielding efficiency of 97.75 ± 2.05 % at low X-ray energy (46 kVp). Moreover, under visible light, the membrane generates reactive oxygen species, resulting in the efficient removal of 98.03 % of methylene blue (MB), 96.35 % of rhodamine B (Rh.B), and 91.51 % of methyl orange (MO) within 180 minutes. Furthermore, it displays bactericidal activity against E. coli and S. aureus under both dark and light conditions. In natural settings, the composite membrane undergoes gradual degradation in soil, completely decomposing within 28 days due to the influence of rainfall and microorganisms. Consequently, this composite membrane holds significant promise for specialized medical protective applications.

Optimizing O3-type cathode materials with modified collector for sodium-ion batteries: Insights of interfacial reaction between collector and electrolyte

In order to obtain a sodium-ion battery with high energy density and good kinetic properties, high specific capacity of O3-type NaNi1/3Fe1/3Mn1/3O2 (NFM111) cathode material and high ion migration rate of NaClO4 electrolyte are selected. The cycling performance of NaNi1/3Fe1/3Mn1/3O2 is tested at 0.5 C after pre-activation at 0.1 C. During the electrochemical testing, a kind of side reaction products are found on the surface of the electrode piece. Through Scanning emission microscopy (SEM), X-ray photoelectron spectroscopy analysis (XPS) and Raman tests, side reaction products are found on the current collector with NaClO4 and Fluoroethylene carbonate (FEC). The protective layers are constructed on the surface of Al foil to effectively avoid the occurrence of side reactions. The prepared half cells have excellent stability and rate performance by the modified current collector. After 100 cycles at 0.5 C, the specific discharge capacity is 106 mA h g−1. The specific discharge capacity at 5 C is 107.2 mA h g−1. This measure provides a new idea to the NFM111 cathode materials electrochemical test and offers research basis for the design of sodium ion battery with excellent dynamic performance. Meanwhile, it also eliminates industry doubts about the performance of sodium-ion batteries.

Alginate's ability to prevent metabolic illnesses, the degradation of the gut's protective layer, and alginate‐based encapsulation methods

AbstractThe gut serves as the body's main immunological and digestive system. Furthermore, host immunity is mostly managed there. Nutrients are further broken down and absorbed here. Numerous research investigations have shown evidence that inflammation, oxidative stress, impairment of the intestinal barrier, and imbalance in the gut microbiota can all contribute to a variety of intestinal illnesses and other issues, underscoring the growing significance of intestinal health concerns. Because of their high biological activity and lack of negative side effects, the organic food‐derived chemicals known as brown algal polysaccharides—mainly fucoidan, laminaran, and alginate—have attracted a lot of attention from academics. Because of its many benefits, sodium alginate is one of the biopolymers that has garnered the greatest attention, research, and application. Carotenoids, which are found in our food, have several positive health effects. Their low solubility in water, oxidation susceptibility, chemical instability, accessibility, and restricted solubility in water, however, restrict their use in food and medicine. In this review and in overcoming these constraints, encapsulation might be helpful. Furthermore, the primary goal of our study is to provide a fresh perspective into the control and avoidance of intestinal diseases. It provides more potent alternatives to this system, clarifies the function of alginates in enhancing the encapsulation of carotenoids, and functions as a model for the synthesis of the intestinal protective agent fucoidan.

Arc Ignition Methods and Combustion Characteristics of Small-Current Arc Faults in High-Voltage Cables

High-voltage cables will continue to operate for a period of time in the event of a small current arc fault, which poses a risk of fire. Two simulated ignition methods, moving electrode and melting fuses, are proposed to analyze the ignition characteristics of low-current arcs. The ignition test was carried out, and the combustion effect was compared. The results indicate that the moving electrode ignition method can achieve long-distance arc ignition test when the current is small and is suitable for simulating the arc ignition situation of cable outer protective layer damage. By controlling the movement speed, it can be ensured that the arc will not be interrupted during the electrode movement process. However, the arc is difficult to sustain using the fuse melting method when the current is small and the distance is long. The fuse melting method is suitable for simulating insulation breakdown situations. The results show that the critical arc duration for cable ignition under five different current conditions of 2–10 A is 28 s, 21 s, 14 s, 9 s, and 4 s, respectively. The maximum height of the cable flame under 2–10 A arc current is 9–52 cm and 16–63 cm, respectively, when the arc duration is 50 s and 100 s. The self-ignition time of the cable after the arc extinguishing is 8–95 s and 14–261 s, respectively. The maximum temperature of the cable flame is positively correlated with arc current, and the maximum flame temperature of the cable under 2–10 A arc current is 540–980 °C. Based on the actual current monitoring data in cable tunnels, the research results can provide reference for the risk assessment and protection of cable tunnel fires.

A-095 A New CO2 Assay with Concentrated Reagent Having Superior Onboard Stability on Mindray BS-2800M Analyzer

Abstract Background Measurement of total content of CO2 in serum or plasma can be used to assist in the diagnosis of various acid-base disorders. There are small amounts (about 0.04%) CO2 in the earth’s atmosphere, or more in an enclosed clinical laboratory space. The environmental CO2 could be dissolved into the CO2 reagent continuously, in particular at lowered temperature when it is opened and stored on the system, which leads an impact on CO2 assay performance. Presently, competitors mainly use additional inserts or with small opening of the reagent container to reduce the contact with air from reagent, to improve its onboard stability. Here, we designed a new CO2 assay by optimizing the reagent formulation with a new protection mechanism to reduce the amount of CO2 absorption to the reagent and improved its onboard stability. This study evaluated performances of the new CO2 assay on Mindray BS-2800M analyzer. Methods Mindray CO2 assay with concentrated reagent is based on PEPC (Phosphoenolpyruvate Carboxylase) enzymatic method. It is designed with an innovative mechanism of reagent formulations with a protective layer of chemical(s) on top of the reagent that prevents CO2 from entering the reagent and reduced its impact to its on-board stability. The onboard stability was conducted with a constant reagent consumption mode to simulate as it in clinical lab use. The onboard study used two levels of Quality Control materials and serum pools. According to CLSI protocols, the following assay performances were evaluated: onboard stability, precision, method comparison, linearity, and interference. Results On Mindray BS-2800M analyzer, Mindray CO2 assay demonstrated an excellent onboard stability. With uncapped reagent on the system, the stability is for 21 days without recalibration, with less than ± 5% deviation from day zero. In parallel onboard stability studies, with Roche CO2 reagent on Cobas c701 system, the relative deviation from day zero was found to be within ±10%; and other three manufacturers` results with deviation exceeded ±10% vs. day zero in 7 days. The linearity of Mindray CO2 assay was determined as from 2.0 to 50.0 mmol/L. Our CO2 assay correlated well with Roche CO2 on Cobas c701 (Mindray = 1.0032 * Roche - 0.0186, r≥0.99). The repeatability and with-lab CVs were ranged from 0.64% to 3.41%, respectively. There was no significant interference (<±10%), at CO2 concentration of 15 mmol/L with bilirubin up to 60 mg/dL,hemolysate up to 800 mg/dL, Intralipid up to 1000 mg/dL, triglycerides up to 1000 mg/dL. Conclusions On Mindray BS-2800M analyzer, the new CO2 assay demonstrated a good ability against environmental CO2 inference in 21 days of onboard time. The new CO2 assay also shown good performances in precision, correlation (accuracy) and anti-interference from endogenous substances. Therefore, we conclude that the new Mindray CO2 assay is suitable for routine clinical laboratory use.

Self-healing of cracks in cement-based materials through bio-mineralization of low air-dependency microorganisms

Microbial self-healing technology for concrete is attracting widespread attention due to its environmentally friendly, non-toxic, and sustainable attributes. Currently, microbial agents utilized in concrete exhibit a high dependence on atmospheric conditions, relying on atmospheric oxygen to activate or capture carbon dioxide from the air for the generation of carbonate ions. This paper introduces an innovative low-dependency microbial restorative aimed at augmenting the self-healing capability of concrete by nearly doubling the available carbonate ions and providing 80 % of them internally, especially targeting deep cracks. A pioneering approach was employed by combining microorganisms that rapidly produce carbon dioxide with those that expedite carbon dioxide hydration. Microbial functional components were meticulously pelletized to create core-shell structure restorative particles, featuring an outer protective layer constructed with low-alkali cement. This study investigates the mechanism through simulation and experimentation, including substrate conversion, carbon dioxide transformation, and the generation and accumulation of carbonate ions and calcium ions. Essentially, this research not only presents a path towards reduced atmospheric dependence but also provides valuable insights for comprehending the mechanism behind microbial self-healing concrete.

Coupled computational fluid dynamics-discrete element method for simulating the interactions between ship-induced waves and riprap on restricted waterway banks

In inland waterways, waves generated by passing boats cause the movement of riprap used for bank protection and stabilization. Previous studies have mainly concerned the natural channel erosion problem caused by wind-generated waves and neglected the research and findings on shipping behavior. This work presents a coupling of the computational fluid dynamics model and the discrete element method. The aim is to first study the interactions between ship waves in the confined channel and the movements of the riprap of the banks and shorelines and second to analyze the stability of these armourstones under the actions of various ship velocities and draught depths. These varying conditions exert influence on the ship-induced waves, the crucial point being the drawdown amplitude, and consequently create more intense flow behavior in the near-shore region, which results in instability and destruction of the overall structure of the armor protection layer. The higher ship velocity and the larger draught depth lead to the aggravation of instability processes of the blocs composing the protective layer. There is a critical phenomenon in the influence mechanism of vessel velocity, whereas the variation process induced by draught depth is relatively linear. In addition, the stability of the blocs also depends on their shapes, sizes, and the initial positions within the protective layer. This study could contribute to the high-quality development of inland navigation.

Microstructure evolution and degradation process of AlCrTiSiN coatings with different Si contents at high temperatures

The microstructure evolution of AlCrTiN and AlCrTiSiN coatings containing 4, 6.8, and 10.6 at.% Si was studied at temperatures ranging from 800 to 1100 °C. The AlCrTiN coating exhibits a single-phase fcc-(Al,Cr,Ti)N structure, while the AlCrTiSiN coatings transition from a nanocomposite structure, composed of fcc-(Al,Cr,Ti)N and amorphous a-SixNy, to a fully amorphous structure as the Si content increases. The hardness and adhesion strength of coatings initially rise, peaking at 24 GPa and 44 N respectively, due to the formation of the nanocomposite structure. However, these properties decline as the coatings become fully amorphous. At elevated temperatures, severe oxidation leads to the gradual formation of layered oxides. Concurrently, phase transformation, spinodal decomposition, and crystallization occur within the nitride layer. The addition of Si enhances oxidation resistance by promoting the rapid formation of a dense and protective oxide layer, and by reducing nitrogen release and TiO2 formation. However, at 1000 and 1100 °C, the coating with 10 at.% Si exhibits slightly faster oxidation compared to the 6.8 at.% Si coating, as the increased Si content reduces the Al content, limiting the coating's ability to regenerate the protective oxide layer.

Lithiophilic Protective Dual Layer Enabling Stable Electrodeposition of Lithium at High Current Density

Lithium (Li) is an ideal anode material for rechargeable batteries and thus manufacturing Li metal is crucial for the practical development of Li metal batteries. Electrodeposition is an efficient technique for producing ultrathin and scalable Li metal electrodes. However, the dendritic growth and the side reactions of Li with electrolyte during the electrodeposition are the main obstacles to overcome. In this study, we designed a pre-coated protective dual layer (PDL) composed of a poly(ethylene oxide)-based solid polymer electrolyte (SPE) and a polydopamine-coated cellulose membrane (PD-CM). The adhesive and ion-conductive SPE layer suppressed the growth of Li dendrites and side reactions with liquid electrolyte. The PD-CM layer with high porosity and lithiophilicity promoted a facile and uniform Li-ion flux. By applying the pre-coated PDL, Li was uniformly electrodeposited on the Ag-coated Cu at a high current density of 6 mA cm−2. The Li/LiFePO4 cell composed of an electrodeposited Li anode with PDL and a LiFePO4 cathode was assembled without an additional separator, and its cycling performance was evaluated. The cell initially delivered a high discharge capacity of 154.8 mAh g−1 at 45 °C and exhibited excellent cycling stability with a capacity retention of 97.0% after 200 cycles.

Lithium p-toluenesulfinate-coated poly(imide) separators for enhanced safety and electrochemical performances of lithium-ion batteries

Increasing the energy density of lithium-ion batteries enhances their applicability; however, ensuring their safety remains a critical issue in the energy society. Herein, we report the development of a lithium p-toluenesulfinate (PTSL)-coated polyimide (PI) separator with improved safety and electrochemical performance during cycling. It is anticipated that integrating PTSL particles into the PI separator will mitigate the risk of internal short circuits by clogging the porous structure of the PI separator and enhance the interfacial stability of the electrode materials. The PTSL is expected to act as an effective component of protective layers, physically separating the cathode from direct contact with electrolytes. The PTSL-embedded PI separator regulated the porous structure inherent to the PI separator, thereby enhancing its physical and thermal properties, such as improved wetting characteristics (evidenced by higher ionic conductivities and lithium-ion transference numbers) and thermal behaviors (reduced shrinkage and more stable thermal decomposition behaviors). During cycling, the cells with the PTSL-coated PI separator demonstrated increased cycling retention compared to the cells with graphite/NCM811 electrodes because the additional PTSL-based protective layers mitigated the electrolyte decomposition upon cycling.

Corrosion mitigation of carbon steel in sulfuric and hydrochloric acid solutions by Syzygium polyanthum (Wight) Walp. leaf extract

It is widely recognized that corrosion has been a persistent issue throughout human history. Over time, various effective strategies have been suggested and successfully employed to combat this problem. Among them, the utilization of inhibitors stands out as a promising, versatile, and easily applicable method. Considering the drawbacks associated with previous substances such as environmental concerns and high operational expenses, plant extracts have emerged as an effective alternative. In there, Syzygium polyanthum (Wight) Walp. stands out as a popular species characterized by a high concentration of polar compounds that is crucial for the formation of a protective film layer on carbon steel. Consequently, this work centers on investigating the corrosion inhibition behavior of Syzygium polyanthum (Wight) Walp. leaf water-extract (SPWE) for carbon steel in different solutions, including 1.0 M HCl, 0.5 M H2SO4, and co-volume acidic mixture, by employing electrochemical and surface techniques. The findings reveal that 2000 ppm of SPWE proved inhibition efficiency exceeding 94.24, 66.27, and 95.02% (estimated by Tafel extrapolation) for carbon steel in 1.0 M HCl, 0.5 M H2SO4, and acidic mixture solutions, respectively. High inhibition performance was also ensured by high polarization resistances (Rp) observed on electrochemical impedance spectroscopy (EIS) and linear polarization resistance (LPR). Increasing corrosion resistance could be due to the protective layer formed on the inhibited samples, while severe corrosion occurred on the uninhibited steel due to extensive damage across the entire surface. Hence, the study underscores the noteworthy impact of chloride and sulfate ions on corrosive inhibition process of SPWE.

Improving structure stability of single-crystalline Ni-rich cathode at high voltage by element gradient doping and interfacial modification

Single-crystalline Ni-rich cathodes can provide high energy density and capacity retention rates for lithium-ion batteries (LIBs). However, single-crystalline Ni-rich cathodes experience severe transition metal dissolution, irreversible phase transitions, and reduced structural stability during prolonged cycling at high voltage, which will significantly hinder their practical application. Herein, a Li4TeO5 surface coating along with bulk Te-gradient doping strategy is proposed and developed to solve these issues for single-crystalline Ni-rich LiNi0.90Co0.05Mn0.05O2 cathode (LTeO-1.0). It has been found that the bulk Te6+ gradient doping can lead to the formation of robust Te–O bonds that effectively inhibit H2-H3 phase transformations and reinforce the lattice framework, and the in-situ Li4TeO5 coating layer can act as a protective layer that suppresses the parasitic reactions and grain fragmentation. Besides, the modified material exhibits a higher Young’s modulus, which will be conducive to maintaining significant structural and electrochemical stability under high-voltage conditions. Especially, the LTeO-1.0 electrode shows the improved Li+ diffusion kinetics and thermodynamic stability as well as high capacity retention of 95.83% and 82.12% after 200 cycles at the cut-off voltage of 4.3 and 4.5 V. Therefore, the efficacious dual-modification strategy will definitely contribute to enhancing the structural and electrochemical stability of single-crystalline Ni-rich cathodes and developing their application in LIBs.

The Corrosion Characteristics of Graphite Coatings on Nickel Foam and Their Applications in High-Temperature Proton Exchange Membrane Fuel Cells

This study investigates the effectiveness of graphite coatings on nickel foam for use in high-temperature proton exchange membrane fuel cells (HT-PEMFCs). Nickel foam, known for its high porosity and good conductivity, serves as an advantageous alternative to traditional flow channels but faces corrosion challenges in HT-PEMFCs, especially from phosphoric acid leakage. Graphite coatings are used as the protection layer and compared with nitride coatings. Chemical vapor deposition process parameters are first optimized for graphite growth. Corrosion polarization curves are then measured using a high-temperature phosphoric acid three-electrode system simulating HT-PEMFC conditions, followed by an analysis of the surface morphology of the samples. Subsequently, the performance and durability of the nickel foams with different coatings are evaluated after being assembled in single fuel cells. The results highlight the superior corrosion resistance of graphite coating under HT-PEMFC conditions, demonstrating its performance over other coatings. Graphite-coated foams showed a significant reduction in corrosion current, approximately 58% lower than uncoated foams and 21% lower than the TiN coated foams. In practical applications, an HT-PEMFC single cell with graphite-coated nickel foam demonstrated a current density of 763 mA/cm2 at 0.6 V under conditions of 180 oC and 2 atm H2/air. The current density is 40% higher than that of the uncoated nickel foam. The results show notable long-term durability under constant current holding tests at 160 oC. The voltage decay rate in the graphite-coated cell was 48% lower compared to the cell with uncoated nickel forms.