Surface Protection Research Articles

Multi‐Species Surface Reconstruction for High‐Efficiency Perovskite Nanocrystal Light‐Emitting Diodes

AbstractAlthough colloidal perovskite nanocrystal (PNC) solution has exhibited near‐unity photoluminescence quantum yield (PLQY), the luminance would be severely quenched when the PNC solution is assembled into thin films due to the agglomeration and fusion of NCs caused by the exfoliation of surface ligands and non‐radiative Förster resonance energy transfer (FRET) from small to large particle sizes, which seriously affected the performances of light‐emitting diodes (LEDs). Here, we used Guanidine thiocyanate (GASCN) and Sodium thiocyanate (NaSCN) to achieve effective CsPbI3 PNC surface reconstruction. Due to the strong coordination ability of these small molecules with the anions and cations on the surface of the PNCs, they can provide strong surface protection against PNC fusion during centrifugal purification process and repair the surface defects of PNCs, so that the original uniform size distribution of PNCs can be maintained and FRET between close‐packed PNC films is effectively suppressed, which allows the emission characteristics of the films to be preserved. As a result, highly oriented, smooth and nearly defect‐free high‐quality PNC thin films are obtained, with PLQY as high as 95.1 %, far exceeding that of the original film, and corresponding LEDs exhibit a maximum external quantum efficiency of 24.5 %.

Fabrication of and corrosion prevention mechanisms of tin oxide (SnO2) decorated reduced graphene oxide (rGO) for anodic protection of Zn metal surfaces

The hydrothermal approach was utilized to prepare SnO2 and rGO-SnO2 composite, and its physicochemical properties and corrosion resistance application are examined in this study. The results suggest that the SnO2, rGO-SnO2 composite exhibits a well-defined and uniform morphology, with SnO2 NPs homogeneously distributed and anchored on the rGO. XRD analysis confirms the crystalline tetragonal structure with 19.1 nm and 20.8 crystalline size. Further, the corrosion resistance application of the rGO-SnO2 composite is evaluated through electrochemical measurements, such as potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The composite-coated substrate is subjected to NaCl electrolyte using a Zn plate. The corrosion performance is compared with that of bare Sn and rGO-SnO2 counterparts to assess the synergistic effect of the composite which exhibits enhanced anticorrosion properties. The synergistic effect of Sn and rGO in the composite offers superior corrosion resistance, making it a promising material for various corrosion-prone applications. Overall, the findings contribute to developing novel and effective strategies for combating corrosion, ensuring the durability and reliability of materials in diverse industrial environments.
 KEY WORDS: Sn-rGO composite, Tafel plot, Corrosion protection, Surface analysis, Synergistic effect
 Bull. Chem. Soc. Ethiop. 2024, 38(2), 445-456. 
 DOI: https://dx.doi.org/10.4314/bcse.v38i2.12

The impact of hBN layers on guided exciton–polariton modes in WS2 multilayers

Abstract Guided exciton–polariton modes naturally exist in bare transition metal dichalcogenide (TMDC) layers due to self-hybridization between excitons and photons. However, these guided polariton modes exhibit a limited propagation distance owing to the substantial exciton absorption within the material. Here, we investigated the impact of hexagonal boron nitride (hBN) layers on guided exciton–polariton modes in WS2 multilayers. By integrating hBN layers, we demonstrate a notable enhancement in the quality of guided exciton–polariton modes. The hBN layers can reduce substrate surface roughness and provide surface protection for the WS2 layer, mitigating inhomogeneous broadening of the exciton resonance. Consequently, we experimentally observed that the propagation distance of polariton modes substantially increased with hBN layers. Additionally, the polariton spectrum broadened due to efficient exciton relaxation to the polariton states at lower energies. Comparison with simulation data emphasizes that the observed improvements are primarily attributed to enhanced exciton quality. The promising outcomes with hBN encapsulation suggest its potential to overcome strong excitonic losses of the guided exciton polariton in implementing nanophotonic devices. Furthermore, this approach provides a new avenue for exploring the novel physics of guided exciton–polariton modes and their potential applications in polariton-based all-optical integrated circuits.

Characteristics and health risks of the inhalable fraction of metal additive manufacturing powders

AbstractMetal additive manufacturing (AM) is gaining traction but raises worker health concerns due to micron‐sized powders, including fine inhalable particles. This study explored particle and surface characteristics, electrochemical properties, metal release in artificial lysosomal fluid (ALF), and potential toxicity of virgin and sieved virgin Fe‐based powders, stainless steel (316L), Fe, and two tooling steels. Virgin particles ranged in size from 1 to 100 µm, while sieved particles were within the respirable size range (<5–10 µm). Surface oxide composition differed from bulk composition. The Fe powder showed low corrosion resistance and high metal release due to a lack of protective surface oxide. Sieved particles of 316L, Fe, and one tooling steel released more metals into ALF than virgin particles, with the opposite was observed for the other tooling steel. Sieved particles had no notable impact on cell viability or micronuclei formation in human bronchial epithelial cells. Inflammatory response in human macrophages was generally low, except for the Fe powder and one tooling steel, which induced increased interleukin‐8 (IL‐8/CXCL‐8) and monocyte chemoattractant protein‐1 (MCP‐1/CCL‐2) secretion. This study underscores distinctions between virgin and sieved Fe‐based powders and suggests relatively low acute toxicity.

Quasi-in-situ Observation and SKPFM Studies on Phosphate Protective Film and Surface Micro-Galvanic Corrosion in Biological Mg–3Zn–xNd Alloys

Quasi-in-situ Observation and SKPFM Studies on Phosphate Protective Film and Surface Micro-Galvanic Corrosion in Biological Mg–3Zn–xNd Alloys

Surface Protection and Activation of Mid-IR Plasmonic Waveguides for Spectroscopy of Liquids

Surface Protection and Activation of Mid-IR Plasmonic Waveguides for Spectroscopy of Liquids

Combining laser surface texturing and double glow plasma surface chromizing to improve tribological performance of Ti6Al4V alloy

Ti6Al4V (TC4) alloy has been widely applied in the military, industrial, chemical, and medical fields due to their excellent thermal stability, corrosion resistance, and biocompatibility. However, titanium alloys are notorious for their poor tribological properties, such as their high friction coefficients and low surface bearing capacities. To tackle this problem, combination of laser surface texturing (LST) and double glow plasma chromizing was conducted to improve the wear resistance of TC4. LST was first conducted to produce uniform dimples with a diameter of 300 μm and gradient density of 11 % on the Ti6Al4V substrate. A chromizing coating (Cr-coating) was subsequently deposited on the surfaces of the textured and raw Ti6Al4V alloy by double glow plasma surface alloying (DGPSA). A continuous and compact Cr-coating with a thickness of about 55 μm was formed on TC4 after being maintained at a temperature of 850 °C, and the coating was mainly composed of a solid solution and intermetallic compounds of Cr2Ti phases. The surface hardness after alloying was two times higher than that of the TC4 substrate. Comparative assessments on the wear resistance of the Cr-coatings with and without LST treatment and the TC4 alloy were carried out using a ball-on-disk wear tester. The results showed that the mass loss and specific wear rate of the duplex-treated sample were 1.54 mg and 7.14 × 10−4 mm3·N−1·m−1. The mass loss and specific wear rate of the TC4 were 4.32 mg and 1.62 × 10−3 mm3·N−1·m−1. The specific wear rates of the four tested samples were in the following order: the duplex-treated TC4 < textured TC4 < chromized TC4 < polished TC4. The coating obtained by LST-double glow plasma chromizing duplex treatment exhibited an outstanding durability and the best mechanical performance. Thus, this approach be used for the protection of Ti6Al4V surface in engineering components and medical instruments.

Simple protocol for combined extraction of exocrine secretions and RNA in small arthropods.

The integration of data from multiple sources and analytical techniques to obtain novel insights and answer challenging questions is a hallmark of modern science. In arthropods, exocrine secretions may act as pheromones, defensive substances, antibiotics, as well as surface protectants, and as such they play a crucial role in ecology and evolution. Exocrine chemical compounds are frequently characterized by gas chromatography-mass spectrometry. Technological advances of recent years now allow us to routinely characterize the total gene complement transcribed in a particular biological tissue, often in the context of experimental treatment, via RNAseq. We here introduce a novel methodological approach to successfully characterize exocrine secretions and full transcriptomes of one and the same individual of oribatid mites. We found that chemical extraction prior to RNA extraction had only minor effects on the total RNA integrity. De novo transcriptomes obtained from such combined extractions were of comparable quality to those assembled for samples that were subject to RNA extraction only, indicating that combined chemical/RNA extraction is perfectly suitable for phylotranscriptomic studies. However, in-depth analysis of RNA expression analysis indicates that chemical extraction prior to RNAseq may affect transcript degradation rates, similar to the effects reported in previous studies comparing RNA extraction protocols. With this pilot study, we demonstrate that profiling chemical secretions and RNA expression levels from the same individual is methodologically feasible, paving the way for future research to understand the genes and pathways underlying the syntheses of biogenic chemical compounds. Our approach should be applicable broadly to most arachnids, insects, and other arthropods.

Effect of the elevated temperature on the wear behavior of Laser Metal Deposition IN718 repairs

IN718, a nickel-based superalloy popular in aerospace, has good high-temperature mechanics/corrosion resistance. Laser Metal Deposition (LMD) repairs using IN718 are extensively explored, yet few studies delve into their tribological aspects. This research examines post-treated IN718 coatings, mimicking rapid repairs, investigating their high-temperature tribological behavior. Samples underwent tribological tests at diverse loads and temperatures. Results show the scanning strategy does not impact the wear behavior. At elevated temperatures, a glaze layer forms in the contact zone, impacting lubrication and surface protection based on its uniformity. Despite its advantageous lubricating ability, at 400°C and 50 N force, the oxidized debris layer lacks mechanical stability. IN718 LMD repairs manifest enhanced high-temperature wear resistance compared to ambient conditions, attributed to the glaze layer.

Inspired trifunctional adsorption films of branched molecules on copper surface for protection

This study developed a method to realise triple resistant effects of new branched molecules for copper surface in aqueous solution. The adsorption of the studied molecules on copper surface was analysed. The results demonstrate that the copper surface adsorbed by the studied molecules showed super resistance effects on Chlorella sp., Escherichia coli and Staphylococcus aureus. The dramatic corrosive suppression of the branched compounds on copper in 0.5 M H2SO4 solution was revealed by the potentiodynamic polarisation and electrochemical impedance spectroscopy at 298 K. By establishing a simple chemical strategy to construct the branched molecules, the multiple inhibition properties of the target molecular adsorption layers on copper can be controlled on the molecular scale.

Mold Resistance of Bamboo after Laccase‐Catalyzed Fixation of Lignin Nanoparticles

AbstractIn this study lignin nanoparticles (LNPs) and iodolignin nanoparticles (ILNPs) were prepared in aqueous medium and subsequently deposited on the bamboo surfaces via laccase catalyzed reaction. The SEM micrographs of blocks treated with LNPs and ILNPs revealed a layer of nanoparticles with a mean particles size of 100 nm and 215 nm. Besides that, the fungal isolates from the bamboo culm of Dendrocalamus asper shared 99 %, 98 % and 100 % similarity with Penicillium sumatrense, Pleosporales and Cunninghamella species. The treatment of ILNPs exhibited maximum biocidal efficacy at 91 % against P. sumatrense, Pleosporales sp. and Cunninghamella sp. After leaching with ultrapure water, LNPs‐treated blocks exhibited a reduced biocidal effectiveness with an efficacy of 67 %. In contrast, bamboo treated with ILNPs exhibited a higher level of resistance to decay than LNPs. The reduction in mass of 2 %, 3 %, and 1 % was observed when subjecting P. sumatrense, Cunninghamella, and Pleosporales species to treatment with ILNPs. This study demonstrates the application of laccase catalysis in both LNPs and ILNPs, indicating a potentially effective approach for providing surface protection to bamboo against plant pathogenic fungi.

Research Progress on Surface Damage and Protection Strategies of Armature-Rail Friction Pair Materials for Electromagnetic Rail Launch.

Electromagnetic rail launch technology has attracted increasing attention owing to its advantages in terms of range, firepower, and speed. However, due to electricity-magnetism-heat-force coupling, the surface of the armature-rail friction pair becomes severely damaged, which restricts the development of this technology. A series of studies have been conducted to reduce the damage of the armature-rail friction pair, including an analysis of the damage mechanism and protection strategies. In this study, various types of surface damage were classified into mechanical, electrical, and coupling damages according to their causes. This damage is caused by factors such as mechanical friction, mechanical impact, and electric erosion, either individually or in combination. Then, a detailed investigation of protection strategies for reducing damage is introduced, including material improvement through the use of novel combined deformation and heat treatment processes to achieve high strength and high conductivity, as well as surface treatment technologies such as structural coatings for wear resistance and functional coatings for ablation and melting resistance. Finally, future development prospects of armature-rail friction pair materials are discussed. This study provides a theoretical basis and directions for the development of high-performance materials for the armature-rail friction pair.

Improved tribological performance and enhanced tensile adhesive strength of micro- to near-nanocrystalline WC-17 wt. %Co coatings sprayed using HVOF

This study investigated the performances of micro- and near-nanocrystalline coatings of WC-17 wt.% Co applied to a steel substrate using the high-velocity oxy-fuel (HVOF) spraying method. The near-nanocrystalline coatings exhibited reduced decarburization, as shown by the XRD and Rietveld refinement analyses. SEM analysis revealed small grain size, low porosity, and uniform surface texture in the near-nanocrystalline coatings. These coatings exhibited superior properties, including a high hardness (∼1298 HV), high tensile adhesive strength (≈9890 PSI), low wear rate (∼0.0011 mm3/m), and minimal wear volume loss (∼0.022 mm3), surpassing microcrystalline coatings. Near-nanocrystalline coatings exhibited 52.17 % less wear volume loss, attributed to factors such as smaller particle size, denser coating structure, reduced porosity, limited decarburization, and the high hardness of near-nanocrystalline coatings. Triboscopic analysis further confirmed their exceptional wear resistance, low wear volume loss, and low coefficient of friction, suggesting that near-nanocrystalline coatings could be effective for protecting substrates in demanding critical conditions, align with the Boeing Standard BSS 7072 requirements, and hold promise as robust surface protection solutions.

Long-Term Performance of Soybean-Based Concrete Surface Protectant under Laboratory Accelerated Aging Conditions

Soy methyl ester-polystyrene (SME-PS) is an organic material derived from soybeans, which has proven to be an effective protectant for concrete surfaces. This study investigated the long-term performance of cement paste samples treated with SME-PS under laboratory accelerated aging conditions (AAC). The specimens were subjected to cyclic conditions: 8 h of UVA radiation (simulating solar radiation), followed by 6 h of darkness with water condensation and a high temperature of 40°C for 28 days. After the AAC exposure, the samples were immersed in a deicing salt solution, specifically a 29.8 wt. % calcium chloride solution, for 7 days. To evaluate the long-term behavior of SME-PS, a series of experiments, including visual observation, thermogravimetric analysis (TGA), and low-temperature differential scanning calorimetry (LT-DSC) was conducted. Visual observations revealed slight damage in SME-PS-treated samples after AAC exposure, while control samples experienced microcrack formations. SME-PS chemical compositions remained unaffected by AAC, in contrast to the control samples where a decrease in the quantity of calcium hydroxide and an increase in calcium carbonate content were observed as a result of carbonation during AAC exposure. LT-DSC results indicated that SME-PS-treated samples showed a significant reduction in the enthalpy of fusion associated with calcium oxychloride (CAOXY) formation, indicating that the SME-PS remained effective after AAC exposure, while control samples exhibited higher CAOXY enthalpy of fusion.

Hydrophobic phytic acid conversion layers for corrosion protection of steel surfaces

AbstractThe possibility for a good conversion protection based on phytic acid (PA) solutions is described many times in the literature.1,2 The latest results show that PA cannot improve the corrosion protective properties with an organic coating,2 although PA conversion layers without organic coatings have already successfully been applied on different surfaces and the development of layers with enhanced corrosion protective behavior was possible.3,4 The reason why PA does not work together with an organic coating is based on the hydrophilic surface and therefore the low contact angle of the PA conversion layer.2 One solution is to modify PA directly and/or change the solution properties to increase the hydrophobic properties. In this work, a new and innovative way to synthesize a new type of sustainable organic PA-based conversion layers on steel, which works completely without titanium or zirconium and is a new approach for hydrophobic conversion layers, is presented.5 The results prove the formation of a pure PA-based conversion layer on the surface. The infrared (IR), Raman, and nuclear magnetic resonance (NMR) spectroscopy verified the new synthesis products and by means of the vibration spectroscopy, the resulting conversion layers. To analyze the new physical properties, the contact angle of the conversion layers was detected. By means of the electrochemical impedance spectroscopy (EIS), the electrochemical stability of the conversion was studied and with cyclic voltammetry (CV), the solidity ratio was investigated. At last, the corrosion protective performance of the layers in combination with an E-coat in the salt spray test (SST) was examined. All modified PA-based conversion layers in combination with E-coats increased the corrosion protective properties in relation to industrial used phosphate conversion layers of steel surfaces. The overall result is a new kind of hydrophobic phytic acid-based conversion layer which shows advanced anticorrosion and coatability properties compared to other layers based on PA. The results if the EIS measurements show that the resistance of the coating significantly increased, and diffusion could be suppressed by coating the metal surface with PA conversion layers. The comparison of the SST results for the reference and the modified PA underline these observations. The overall SST rating increased by 2 and the delamination went down to 1.9 mm while the corrosion was 0.1, comparable to phosphated steel.

Fully bio-based water-resistant wood coatings derived from tree bark.

Surface protection is essential when using wood as a construction material. However, the industry lacks sustainable alternatives to replace the presently dominant fossil-based synthetic water-resistant coatings. Here, we show a fully bio-based wood surface protection system using components sourced from birch bark and spruce bark, inspired by the natural barrier function of bark in trees. The coating formulation contains suberinic acids and spruce bark polyphenols, resulting in a waterborne suspension that is safe and easy to apply to wood. The polyphenols play a dual role in the formulation as they stabilize the water-insoluble suberinic acids and serve as nanofillers in the thermally cured coating, enabling the adjustment of the mechanical properties of the resulting coating. When applied to spruce wood, the coating formulation with 10% polyphenol and 90% suberinic acids achieved a water absorption value of 100 g m-2 after 72 hours of water exposure, demonstrating superior performance compared to an alkyd emulsion coating. We conclude that instead of combusting tree bark, it can serve as a valuable resource for wood protection, closing the circle in the wood processing industry.

Arterial and venous supply of the Harderian gland in hens.

The Harderian gland in domestic birds is a major paraocular excretory gland that has an important role in tear production as well as in the immune protection of the conjunctiva surface. The aim of this research was to investigate the arterial and venous supply of the gland in hens and provide valuable and useful information for future research. The research was conducted on 26 adult hens, provenience of Lohmann Brown. For the identification and determination of blood vessels, we used the vascular corrosion cast technique in conjunction with the transmission electron microscope (TEM). The casts showed that the gland receives the arterial supply via branches of a. ophthalmotemporalis and a. nasalis communis and these arteries are accompanied by the corresponding veins. Ultrastructural analyses showed the presence of fenestrated capillaries, which indicates the possibility for permeability of larger molecules. The present research gives important and detailed information about the arterial and venous supply of the Harderian gland in hens that may serve as guidelines for future vascular and morphological investigations.

In vitro evaluation of effect of new fungicides against yellow spot (pyrenophora tritici-repentis) of wheat

In response to the producers’ concerns about reducing the cause of wheat yield loss from the necrotrophic pathogenic fungus Pyrenophora tritici-repentis, which informed the purpose of this study, to investigate the effectiveness of fungicides in reducing the prevalence of yellow spot during artificial infection in the field conditions of the Republic of Dagestan and the Rostov region. The experimental design included: T1) Taxis, SC (240 g/l azoxystrobin + 160 g/l epoxiconazole) (0.5 l/ha); T2) Taxis, SK (0.6 l/ha); T3) Spirit, SC (240 g/l azoxystrobin + 160 g/l epoxiconazole) (standard) (0.6 l/ha); and T4) Control (without treatment). On control plots, the prevalence of yellow spots corresponded on average to 32.5% (Homer) and 37.2% (Grom) for winter wheat varieties and 32.6% (Malachite) as well 35.7% (Prokhorovka) for spring wheat varieties respectively. At the same time, the smallest disease prevalence was observed in the treated variants T1, T2, and T3, on average 2.6–6.5%. Furthermore, the effective protection of the leaf surface during the 2-fold treatment of wheat crops with fungicides led to an increase in yield in both study regions from 11 to 19%.

Novel advancements in protection of steel surfaces using polystyrene supported nanoparticles of metallic zinc as sacrificial corrosion inhibitors

Corrosion poses a significant challenge, causing severe damage to steel infrastructures across various industries, particularly those involved in delivering fossil fuel sources.

The role of exocytotic proteins in the (dys)regulation of human reflex tearing and aqueous‐deficient dry eye syndrome

Aims/Purpose: Reflex tears triggered by various external and internal stimuli play vital functions in the protection of the ocular surface and visual acuity. The impairment of the molecular processes involved in reflex tearing is conjectured to be associated with the progression of dry eye syndrome (DES). Therefore, this study was undertaken to unravel the intricate proteome changes in the reflex and DES tears.Methods: Thirty six subjects underwent basic secretory test (BST) via Schirmer I (without anaesthetics) to determine the secretory rate of the lacrimal gland due to the irritating nature of the strip and were divided into reflex (RF, n = 12, BST = 35.0 ± 0.0), normal (NR, n = 12, BST = 15.3 ± 3.0) and severe aqueous‐deficient DES (DRY, n = 12, BST = 3.4 ± 1.4). The individual tear samples were analysed employing the state‐of‐the‐art mass spectrometry‐based proteomics strategy, followed by bioinformatics analyses to elucidate the underlying molecular processes.Results: A total of 293 and 237 proteins were found to be significantly (p &lt; 0.05) differentially regulated in the RFL vs. NR (up‐regulated, UR = 12; down‐regulated, DR = 281) and DRY vs. NR (UR = 197; DR = 40), respectively. The hallmark of this study was the identification of 10 lacrimal gland‐specific proteins (e.g., LYZ, LCN1, LTF, PRR4, ZG16B) secreted mainly via the exocytotic pathway, which were significantly up‐regulated in the RFL vs. NR but down‐regulated in the DRY vs. NR. Antibacterial response was also significantly activated in RFL (p = 1.9 × 10−2) compared to DRY (p &gt; 0.05). The activated inflammatory response (e.g. S100A8/A9, ANXA1) associated with DRY (p = 2.7 × 10−8, z = 4.0) was found to be inhibited in the RFL (p = 2.7 × 10−9, z = −3.5). Likewise, proteins involved in glycolysis (z = −2.8), acute phase response (z = −2.7) and actin cytoskeleton signalling (z = −2.1) were also inhibited in the RFL compared to DRY.Conclusions: In summary, this study has demonstrated that protein markers involved in the exocytotic pathway play major roles in the production of reflex tears and their regulation is impaired in the DES. Importantly, the abrogation of the vicious cycle of pathways involved in the progression of DES, especially inflammation, was observed in the reflex tears, which may be the key for the protection and maintenance of dynamic balance of the ocular surface.