Coatings, Volume 13, Issue 8 (August 2023) – 175 articles

For the synthesis of ionogels containing microcrystalline cellulose (MCC) and Na-bentonite (Na-Bent), ionic liquid (IL) 1-butyl-3-methylimidazolium acetate was used as an MCC solvent. Characterization and research of the physicochemical properties of the synthesized materials were carried out using methods such as SEM, WAXS, thermal analysis, FTIR, conductometry, and viscometry. WAXS analysis showed an increase in the interlayer distance of Na-bentonite in composites due to the intercalation of IL molecules. Based on the data on the characteristic temperatures of thermal degradation, enhanced thermal stability of triple IL/Na-Bent/MCC ionogels was revealed compared to that for cellulose-free systems. It was found that the electrical conductivity of both triple IL/Na-Bent/MCC and binary IL/MCC ionogels was non-monotonous. The data obtained can be used in the formation of multifunctional coatings with enhanced thermal stability. Full article

High-chromium cast iron (HCCI) coatings with multicomponent carbides were prepared on low-alloy steel substrates using a laser cladding technique in this work. The microstructure and wear resistance of the coatings were characterized via optical microscopy, scanning electron microscopy, transmission electron microscopy, energy-dispersive spectroscopy, X-ray diffraction and block-on-ring wear testing. Multicomponent carbides (Ti, Nb, Mo, W, V)C with an FCC structure and multicomponent compounds (Nb, Mo, W, V) (B,C) with an FCC structure were found in the microstructures of coatings after multielement doping. In addition, (Cr, Mo, W, V)₂₃C₆ compounds could be obtained by heat treatment. These multicomponent compounds were beneficial for obtaining coatings with an excellent hardness (60 HRC) and high wear resistance. This multielement doping method provides an effective modified method for preparing high-wear-resistance laser cladding coatings. Full article

The development process of electrospark deposition (ESD) technology is reviewed, and the principles and differences of ESD technology are discussed in this review. Based on the research status regarding the ESD of titanium alloys, the promotion effect of ESD technology on wear resistance, corrosion resistance, oxidation resistance at high temperatures, and the biocompatibility of titanium alloys was elaborated on. For example, with the use of ESD technology to prepare Ti–Al, TiN, Ni–Cr, and other hardening coatings with high hardness, the maximum hardness of the deposited layer is six times higher than that of the substrate material, which greatly reduces the loss of the material surface in the process of friction in service, and has a high wear–resistance effect. The preparation of a single–phase lamellar coating is more beneficial for improving the oxidation resistance of the substrate. Carbide and a nano–porous coating can effectively enhance the bone integration ability of implants and promote biocompatibility. The application of ESD technology in the surface modification of titanium alloys is reviewed in detail. Finally, the development direction of ESD technology for titanium alloys is proposed. Full article

To address environmental pollution and energy shortage issues, titanium dioxide (TiO₂)-based photocatalysts, as an efficient pollution removal and fuel production technology, have been widely used in the field of photocatalysis. In practical applications, TiO₂-based photocatalysts are usually prepared on various substrates to realize the separation of the catalyst from water and improve photocatalytic stability. Herein, the research progress of TiO₂-based heterogeneous photocatalytic coatings deposited on glass substrates with various deposition techniques is reviewed. Such TiO₂-based composite coatings obtained using different techniques showed excellent self-cleaning, pollution removal, air purification, and antibiosis performance. The various deposition techniques used for the preparation of TiO₂ coatings, such as wet chemical deposition (WCD), electrodeposition, physical vapor deposition (PVD), and chemical vapor deposition (CVD) were discussed together with photocatalytic applications by highlighting the typical literature. Finally, the challenges and prospects of developing TiO₂-based heterogeneous coatings were put forward. Full article

Buried piping is subject to soil corrosion, which can be prevented by combining coatings and cathodic protection to maximize corrosion control. However, even with both methods, coatings are subject to damage from external factors and various causes. Buried piping may expose the metal and alter the current flow, which in turn causes corrosion. Therefore, this study analyzed the effect of detection electrode spacing on the direct current voltage gradient (DCVG) magnitude formed for coated pipelines buried in the soil. The DCVG was measured using a real-time coating defect detection system. FEM model simulations were carried out, and then the result was compared to the measured DCVG magnitude. When the spacing of the detection electrodes increased, the detected signal and signal location changed. The detection reliability increased as the noise signal is eliminated at the optimum detection electrode spacing. However, the detection reliability decreased at higher selection electrode spacing as the noise signal and detected signals together were eliminated. The location of the detected signal shifted as the spacing of the detection electrodes increased due to the change in the detection reference point and signal magnitude. Full article

Iranian white cheese has a dynamic microbial load and moisture content of about 50%–60% and a short shelf-life (about 10 days). As a result, this research aimed to prolong the shelf-life of Iranian white cheese using an antimicrobial whey protein concentrate (WPC) edible coating enriched with 1 and 2% of cumin essential oil (CEO). The microbiological (total bacteria, lactic acid bacteria, and dairy-related pathogen risk), physicochemical (fat, protein, pH, titratable acidity, moisture, and total solid content), color, texture, organoleptic, and sensorial properties of the cheese samples were assessed during 28 days of storage at 4–5 °C. The integration of the WPC and the CEO reduced the moisture content of the films and improved their durability. The presence of the CEO significantly enhanced the mechanical attributes of the films, i.e., Young’s modulus and tensile strength. Cheese samples coated with WPC containing 1 and 2% CEO maintained the moisture content of the cheese samples, decreased the counts of Listeria monocytogenes, Staphylococcus aureus, and Escherichia coli (EHEC) by 2 log after 28 days of storage. The yeast and mold count decreased from 4.6 log CFU·g⁻¹ to 2.1 and 2 log CFU·g⁻¹. The edible coating did not affect the color or texture of samples during the 28 days of storage. The sensory qualities of all samples were identical, demonstrating that the coating did not influence the curd cheese flavor. This study demonstrated that an edible coating made of WPC with the addition of CEO could effectively improve the shelf-life of Iranian white cheese, contribute to the development of a more sustainable manufacturing process, and increase its functional value. Full article

This paper presents the synthesis of the triple substituted carbonated hydroxyapatite with magnesium, strontium and zinc (Mg-Sr-Zn-CHAp), as well as its structural, morphological and compositional characterization. The analytical techniques used (WDXRF, XRD and FTIR) highlighted, on the one hand, the B form for the apatite structure, as well as the presence of the three metal ions in the apatite structure, on the other hand (small shifts of 1120–900 cm⁻¹ and 500–600 cm⁻¹ absorption peaks due to the metals incorporated into the CHAp structure). The ratio between the metallic ions that substitute calcium and Ca²⁺, and phosphorus is increased, the value being 2.11 in comparison with CHAp and pure hydroxyapatite. Also, by using imaging techniques such as optical microscopy and SEM, spherical nanometric particles (between 150 and 250 nm) with a large surface area and large pores (6 m²/g surface area, pores with 6.903 nm diameters and 0.01035 cm³/g medium volume, determined by nitrogen adsorption/desorption analysis) and a pronounced tendency of agglomeration was highlighted. Also, the triple substituted carbonated hydroxyapatite was tested as an inorganic consolidant by using stone specimens prepared in the laboratory. The efficiency of Mg-Sr-Zn-CHAp in the consolidation processes was demonstrated by specific tests in the field: water absorption, peeling, freeze–thaw behavior, chromatic parameters as well as mechanical strength. All these tests presented conclusive values for the use of this consolidant in the consolidation procedures of stone surfaces (lower water absorption, increased mechanical strength, higher consolidation percent, decreased degradation rate by freeze–thaw, no significant color changes). Full article

The development of the bubble generator that can efficiently generate micro-nano bubbles has always been recognized as a challenge. Swirling flow is considered to be an efficient method to enhance hydrodynamic cavitation. The vortex supply chamber and the variable-diameter accelerated vortex cavitation reaction chamber were combined to obtain a stable high-speed tangential liquid flow and improve the cavitation effect inside the generator in this study. The central air intake column was innovatively installed above the cavitation reaction chamber, which prolonged the shear fracture time of bubbles under high shear force and improved the gas–liquid contact and mixing efficiency. The influence of geometric parameters on the internal and external flow fields of the generator was analyzed through the numerical simulation. The optimized central air intake column was located 10 mm above the inlet of the cavitation reaction chamber. The optimized variable diameter contraction angle was 16°, and the optimized generator outlet diameter was 15 mm. Through the bubble performance test, it was verified that the micro-nano bubbles with the minimum size and average size of 0.31 μm and 3.42 μm could be generated by the manufactured generator. The enforcement of the research provided theoretical guidance and data support for the development of efficient micro-nano bubble generators. Full article

This study aimed to develop a cost-effective and eco-friendly mosquito-repellent textile finish based on microcapsules incorporated with limonene, camphor, linalool, menthol, and 1-octanol individually. Essential oil-based microcapsules were prepared by the emulsion extrusion microencapsulation method. The concentration of active components was determined by the gas chromatography-mass spectrometry (GC-MS) technique at different time intervals. The prepared microcapsules were incorporated into the textile finish to prepare an insect-repellent finish and applied to polyester: cotton (40:60) fabric using a conventional pad-dry cure method. Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) analyses were performed to ensure the presence and stability of essential oil components on the fabric. FT-IR spectra showed that peaks observed in the range of (3400–3200 cm⁻¹) and (1720–1600 cm⁻¹) correspond to –OH stretching and bending vibrations in both untreated and microencapsulated essential oil-treated fabric. Mosquito-repellent activity was assessed by exposing treated and untreated fabric to mosquitoes. To study the long-lasting impact of microencapsulation of essential oil components on fabric, mosquito repellency was repeated every 10 to 50 days. Fabrics treated with microencapsulated essential oil components presented higher and longer-lasting protection from mosquitoes than untreated fabrics. Menthol (97%), linalool (93%), and limonene (93%) encapsulated finishes showed significantly higher repellency (>90%) as compared with octanol finishes. The studied mosquito repellent finishes could be ideal candidates for textile finishing industries. Full article

The utilization of waste fibers in the production of reinforced concrete materials offers several advantages, including reducing environmental strain and socio-economic impacts associated with composite waste, as well as enhancing material performance. This study focuses on the development of cementitious mortars using secondary waste carbon fibers, which are by-products derived from the industrial conversion of recycled fibers into woven/non-woven fabrics. The research primarily addresses the challenge of achieving adequate dispersion of these recycled fibers within the matrix due to their agglomerate-like structure. To address this issue, a deagglomeration treatment employing nanoclay conditioning was developed. The functionalization with nanoclay aimed to promote a more uniform distribution of the reinforcement and enhance compatibility with the cementitious matrix. Various fiber weight percentages (ranging from 0.5 w/w% to 1 w/w% relative to the cement binder) were incorporated into the fiber-reinforced mix designs, both with and without nanoceramic treatment. The influence of the reinforcing fibers and the compatibility effects of nanoclay were investigated through a comprehensive experimental analysis that included mechanical characterization and microstructural investigation. The effectiveness of the nanoceramic conditioning was confirmed by a significant increase in flexural strength performance for the sample incorporating 0.75 w/w% of waste fibers, surpassing 76% compared to the control material and exceeding 100% compared to the fiber-reinforced mortar incorporating unconditioned carbon fibers. Furthermore, the addition of nanoclay-conditioned carbon fibers positively impacted compression strength performance (+13% as the maximum strength increment for the mortar with 0.75 w/w% of secondary waste carbon fibers) and microstructural characteristics of the samples. However, further investigation is required to address challenges related to the engineering properties of these cementitious composites, particularly with respect to impact resistance and durability properties. Full article

Similar to the asphalt mixture, the polyurethane (PU) mixture’s performance and characteristics are dependent on many variables. In this study, six variables, including aggregate gradation (limestone and basalt), aggregate type, PU type, PU content, and curing condition, and several parameter analyzing methods were chosen to determine the effect of variables on the dynamic property, rheological property, and rutting resistance of the PU mixture. The limestone aggregate gradation exhibited a substantial effect on the dynamic property, rheological property, and rutting resistance of the PU mixture; the basalt aggregate gradation exhibited significant influence on the dynamic property and rutting resistance, but a moderate effect on the rheological property. The aggregate type could influence the rheological property and rutting resistance. The slow curing speed of the PU binder decreased the dynamic modulus and rutting resistance but did not influence the phase angle. The rise in PU binder content would only improve the PU mixture’s resistance to rutting. The curing condition and color additive had no impact on the PU mixture’s properties. The generalized logistic sigmoidal (GLS) and Christensen Anderson and Marasteanu model (CAM) models could precisely predict the dynamic modulus and phase angle respectively disregarding the PU mixture features. PUM-10/B exhibited the greatest rutting resistance. The findings will aid in comprehending the properties and influencing factors of the PU mixture as well as in designing the desired mixture. Full article

In this paper, an online apparatus was developed for isothermal thermogravimetric measurement of silicide coatings within a wide temperature range (from −180 °C to 2300 °C) based on thermogravimetric analysis. Firstly, the measuring principle and method regarding silicide coatings of this apparatus were studied. Secondly, on the basis of oxidation kinetics analysis, the intrinsic mechanism and kinetic parameters of three stages (oxidation, diffusion, and fall-off) of silicide coatings were studied, and the oxidation kinetics features were also analyzed. In addition, according to mathematical physics methods, a kinetics model of silicide coatings in different stages of oxidation was established, including parameters such as weight change, oxidation rate, oxidation time, etc. Finally, online isothermal experiments from −180 °C to 2300 °C werecarried out and analyzed. The results showed that the kinetic model established in this paper was in good agreement with the oxidation process of silicide coatings. In this paper, a complete kinetics model including different oxidation stages is proposed for the entire oxidation process of a silicide coating, revealing its oxidation mechanism. The research will play a significant role in the study of preparation technology improvement and high-temperature environment application. This paper studied two measuring methods: weight gain and weight loss measuring methods. Also, an experiment was carried out on the silicide coatings to explore the physical oxidation process between −180 °C and 2300 °C. The results proved the perfect consistency of the kinetics model proposed by this paper and the oxidation process of silicide coatings. This paper will play a significant role in the study of preparation technology enhancement and high-temperature environment application. It also provides a theoretical foundation for accelerated aging and life evaluation methods. Full article

Solid lubricating composite TiN coatings with Pb additives were obtained on steel and titanium substrates in the process of reactive magnetron sputtering of separate cathodes. Columnar, columnar nanostructured and composite nanostructured TiN coatings with different contents (3–13%) of a lubricating component (Pb) were obtained by deposition onto rotating and stationary substrates. It was found that deposition at a rotating substrate and 3% Pb content in the TiN matrix led to a columnar crystallite coating structure. With an increase in its content to 8%, columnar crystallites in the structure become less pronounced, and the coating becomes columnar nanostructured. In nanostructured composite coating with 12% Pb, the soft component is distributed both in the matrix and in the form of inclusions. XRD analysis of the composite nanostructured TiN–Pb coating indicates a textureless state. In this case, the diffraction lines of all present phases (Pb, PbO, TiN) are characterized by a significant broadening, indicating that the size of the subgrains are in range of 10–20 nm. Tribological tests of the coatings were carried out at room temperature and under conditions of stepwise heating. The nanostructured composite coating showed the best tribological characteristics due to a high Pb content, a relatively high microhardness (817 HV) and a textureless state with a low grain size. This coating had a low friction coefficient (~0.1) over 50,000 test cycles, both at room temperature and under conditions of stepwise heating up to 100 °C and 200 °C. Full article

Fourth-generation nuclear power systems are based on high-temperature gas-cooled reactors, in which the pebble fuel is the primary energy carrier. In this regard, applying protective pyrocarbon coatings on granulated fuel is an essential problem in ensuring the reliability of nuclear power plants. The article’s main idea is to research rational technological parameters of forming a pyrocarbon protective coating on the granules of a nuclear fuel model. For this purpose, granulated Al₂O₃ with the protective pyrocarbone coating was applied as a fuel model. The article’s aim is to study the effect of thermophysical parameters on applying a protective pyrocarbon coating on granulated Al₂O₃. During the experimental studies, thermal imaging of the pyrolysis process was used. The scientific novelty of the work is the equilibrium curves for the systems Al₂O₃:CH₄, Al₂O₃:CH₄:N₂, and Al₂O₃:CH₄:Ar. Their analysis allowed for evaluating rational thermochemical parameters of the pyrolysis process. As a result, rational thermophysical parameters of coating granulated Al₂O₃ with a pyrocarbon layer were evaluated, and the practical possibility of applying the pyrocarbon coating to granulated Al₂O₃ in the electrothermal fluidized bed was experimentally proven. It was shown that nitrogen does not significantly affect the target reaction product under a temperature of less than 1500 K. Also, the rational conditions for the pyrocarbon coating at a pressure of 0.1 MPa were realized at a temperature of 900–1500 K and using argon. Moreover, pyrocarbon was precipitated from hydrocarbon at 1073–1273 K. Overall, the need to add an inert gas for reducing the carbon black formation was proven to prevent a reduction of natural gas efficiency. Full article

High-entropy materials have attracted extensive attention as emerging electrode materials in various energy applications due to their flexible tunability, unusual outstanding activities, and cost-effectiveness using multiple earth-abundant elements. We introduce a novel high-entropy composite oxide with the five elements of Cu, Ni, Co, Fe, and Cr (HEO-3CNF) for use in the oxygen evolution reaction (OER) in electrocatalytic water splitting. HEO-3CNF is composed of two phases with a non-equimolar, deficient high-entropy spinel oxide of (Cu_0.2−xNi_0.2Co_0.2Fe_0.2Cr_0.2)₃O₄ and monoclinic copper oxide (CuO). Electrochemical impedance spectroscopy (EIS) with distribution of relaxation times (DRT) analysis validates that the HEO-3CNF-based electrode exhibits faster charge transfer than benchmark CuO. It results in improved OER performance with a lower overpotential at 10 mA/cm² and a Tafel slope than CuO (518.1 mV and 119.7 mV/dec versus 615.9 mV and 131.7 mV/dec, respectively) in alkaline conditions. This work may provide a general strategy for preparing novel, cost-effective, high-entropy electrodes for water splitting. Full article

The purpose of this research is to characterize and evaluate the corrosion behavior of zinc coatings used for corrosion protection, with a special focus on the S235 steel material. The introduction highlights the need for corrosion protection in industrial settings, as well as the importance of understanding corrosion processes and the development of corrosion products to develop more effective solutions. The study’s goals are to undertake an extensive analysis of corrosion products formed on the zinc coating’s surface, to evaluate the performance of these coatings under atmospheric circumstances, and to investigate the effect of deposition parameters on coating quality. The essential message provided to readers is the critical significance of knowing corrosion product formation mechanisms and zinc coating corrosion behavior in developing long-lasting and effective protection measures. The study methodology includes cycle testing, morphological and chemical examination of corrosion products, as well as optical and electron microscopy and energy-dispersive spectroscopy. Corrosion resistance is assessed using accurate measurements. The results show that zinc coatings have exceptional corrosion resistance under air settings, with the produced corrosion products offering further protection to the underlying material. Furthermore, the study demonstrates that the surface roughness of S235 steel has a substantial impact on the quality and corrosion behavior of hot-dip galvanized coatings. The findings emphasize the necessity of detailed characterization of corrosion products, the effect of depositional factors on zinc coating performance, and the need for novel corrosion protection methods. These discoveries have significant implications for the corrosion protection sector, providing the potential to improve the longevity and efficiency of protective systems used in industrial applications. Full article

Laser-Directed Energy Deposition (L-DED) is an additive manufacturing technique that has lately been employed to deposit coatings of cemented carbides, such as WC-Co. During deposition, complex microstructural phenomena usually occur, strongly affecting the microstructural and mechanical behavior of the coatings. Post-fabrication heat treatments (PFHTs) may be applied to homogenize and strengthen the microstructure; nevertheless, to the best of the authors’ knowledge, just a few papers deepened the effect of these treatments on cemented carbides fabricated by additive manufacturing. This work evaluates the influence of four PFHTs on the microstructural evolution and hardness of L-DED WC-12Co. For each treatment, different combinations of solubilization time and temperature (between 30 and 180 min and from 400 °C to 700 °C, respectively) were adopted. The microstructure was investigated by optical and scanning electron microscopy equipped with energy-dispersive spectroscopy, whereas the mechanical properties were determined by Vickers hardness measurements. Based on the results, high microstructural heterogeneity in terms of WC particles, η-phase structures, and Co distribution was observed in the sample in the as-built condition. Some cracking defects were also observed in the samples, irrespective of the heat treatment conditions. Finally, a finer microstructure and a lower amount of brittle ternary η-phase, together with an increase in hardness (1030 ± 95 HV10), were found for the highest dwelling times (180 min) and for solubilization temperatures in the range of 500–600 °C. Full article

Metal acetylacetonates belong to the β-diketonate family and are considered as classics among precursors for metal–organic chemical vapor deposition (MOCVD). The success of film preparation is crucially dependent on the volatilization thermodynamics of the precursors used. Data on the volatilization thermodynamics of metal acetylacetonates are in huge disarray. We amassed and analyzed experimental data on the vapor pressures and on the enthalpies and entropies of fusion, vaporization, and sublimation of acetylacetonate tris-complexes of metals(III) (Al, Sc, Cr, Mn, Fe, Co, Ru, Rh, In, and Ir) available in the literary sources. In addition, saturated vapor pressures over crystalline Al(III), Cr(III), and In(III) acetylacetonates and corresponding thermodynamic sublimation properties were determined. New findings enabled us to arbitrate the conflict among literature data. The enthalpies and entropies of sublimation, vaporization, and fusion were adjusted to the reference temperature for a correct comparison using the empirically estimated differences in heat capacities. The heat capacity of the crystalline phase was shown to depend weakly on the metal atom. As a result, a reliable set of enthalpies and entropies of the mentioned processes of fundamental importance was derived for ten metal complexes. Relationships between volatility and structure were established depending on the central metal. The suggested algorithm can be fairly easily transferred to the acetylacetonate or other β-diketonate isoligand complexes with metals of different valence. Full article

Aqueous zinc ion batteries (AZIBs) are considered as one of the most promising energy storage technologies due to their advantages of being low in cost, high in safety, and their environmental friendliness. However, dendrite growth and parasitic side reactions on the zinc metal anode during cycling lead to a low coulombic efficiency and an unsatisfactory lifespan, which seriously hinders the further development of AZIBs. In this regard, metal–organic frameworks (MOFs) are deemed as suitable surface modification materials for the Zn anode to deal with the abovementioned problems because of their characteristics of a large specific surface area, high porosity, and excellent tunability. Considering the rapidly growing research enthusiasm for this topic in recent years, herein, we summarize the recent advances in the design, fabrication, and application of MOFs and their derivatives in the surface modification of the zinc metal anode. The relationships between nano/microstructures, synthetic methods of MOF-based materials, and the enhanced electrochemical performance of the zinc metal anode via MOF surface modification are systematically summarized and discussed. Finally, the existing problems and future development of this area are proposed. Full article

Nanotechnology is one of the most active research fields in materials science. Metal-organic frameworks (MOFs) have the benefits of having a sizable specific surface area, extremely high porosity, changeable pore size, post-synthesis modification, and extreme thermal stability. Graphene oxide (GO) has attracted significant research interest due to its similar surface area to MOFs. Furthermore, oxygen-containing groups presented in graphene oxide offer the unique processing and handling advantages of amphiphilicity and dispersion in water. MOF-based GO has recently attracted attention due to its resemblance to metal ions and organic binding linkers. It has sparked great interest in the past few years due to its distinct characteristics and higher performance compared to MOFs or GO alone. This review aims to describe the most current developments in this topic for researchers. An attempt has been made to provide a synopsis review of recent research on MOFs/GO composites’ properties, synthesis techniques, advantages and challenges, and different applications, including supercapacitors, gas separation and storage, water purification, sensing, catalysis, and biomedical. Full article

The overall rigidity of the cement concrete pavement is high, but there are defects such as easy cracking and insufficient anti-slip performance. The epoxy resin ultra-thin wearing course overlay can effectively solve these issues. However, there is still a lack of knowledge about the long-term performance of epoxy resin ultra-thin wearing course overlay on cement concrete pavement. Therefore, this article analyzed the interlayer adhesion and durability of epoxy resin ultra-thin wearing course overlay through the Hamburg rutting test and a series of shear tests under damp heat, thermal oxygen aging, and ultraviolet (UV) aging conditions. Shear test results indicated that the shear performance of epoxy resin overlay grew with the increase in epoxy resin content and was severely affected by high temperature, and the optimal content was set as 3.4 kg/m². The Hamburg rutting test results showed that the epoxy resin overlay exhibited satisfactory high-temperature performance and water resistance. For the damp heat effect, it was revealed that damp heat led to more significant shear strength loss compared with the overlay specimens without damp heat. The water immersion caused the shear strength decline due to the water damage to the overlay interface. As for the thermal oxygen aging effect, it was reflected that the short-term thermal oxygen aging had a minor impact on the shear performance of the epoxy resin overlay. However, with the increase in thermal oxygen aging duration, the shear strength of the epoxy resin overlay significantly decreased due to the aging of epoxy resin binders. Regarding the UV aging impact, it was also found that the shear performance of the epoxy resin overlay rapidly decreased as the UV aging duration grew whether at 20 °C or 60 °C. Moreover, UV aging led to a more significant impact on the shear performance of the epoxy resin overlay than thermal oxygen aging. Full article

This study investigates the microstructure and tribological behavior of Inconel 625 overlays applied via GMAW (Gas Metal Arc Welding) with and without a 316LSi stainless-steel intermediate layer on top of A36 steel. The microstructural characterization was conducted via FESEM with EDS. The tribological behavior was evaluated using a tribometer in a reciprocating configuration. The results showed that the wear rate of the Inconel 625 weld overlay with the 316LSi intermediate layer was higher than without it. However, no variations were observed in terms of hardness and the friction coefficient of the Inconel 625 weld overlays. The difference in the behavior of the two coatings was justified due to the microstructure morphology found in each case and chemical composition. When applied without the intermediate layer, Inconel 625 coating’s structure was dendritic, whereas it was cellular otherwise. An increase in the amount of Nb was observed in the layer deposited over 316LSi. This rise likely led to an increase in the number of precipitates and/or Laves phase formation. Thus, the results indicated that the difference in thermal conductivity and dilution between the stainless and carbon steels modifies the morphology of the microstructure of the Inconel 625 weld overlay, decreasing wear resistance when deposited on top of the stainless steel. Full article

Nowadays, the application of multicomponent coatings with multiphase nanocrystalline structure is the most promising direction in the search for wear-resistant protective coatings with a full set of necessary operational properties. Nanocrystalline multicomponent coatings based on the Ti-Al-Ta-Si-N system have a high hardness combined with thermal stability and oxidation resistance. Silicon atoms are weakly soluble in the TiN, Ti_1−xAl_xN, and TaN crystalline phases of the Ti-Al-Ta-Si-N system and interact preferentially with N atoms, forming the amorphous Si₃N₄ phase. In this context, it is important to first study the peculiarities of the interaction of Si atoms with the simplest structural units of the Ti-Al-Ta-Si-N system, such as TiN, AlN, and TaN compounds with the NaCl structure. This work is devoted to the study of the interaction of a Si atom with the (001) surface of AlN, TiN, and TaN compounds with the NaCl structure using ab initio calculations. This provides information for a deep understanding of the initial stages of the formation of different crystallites of the considered composite. It was established that the adsorption of silicon on the (001) surface of AlN, TiN, and TaN significantly increases the relaxation of the surface layers and leads to an increase in the corrugation observed on the clean surfaces. The largest corrugation is observed on the surface of the TaN compound. The most energetically favorable adsorption positions of Si atoms were found to be the position of Si above the N atom on the TiN and TaN surfaces and the quadruple coordinated position on the AlN surface. The valence electron density distribution and the crystal orbital Hamiltonian population were studied to identify the type of Si atom bonding with the (001) surface of AlN, TiN, and TaN compounds. It was found that silicon forms predominantly covalent bonds with the nearest metal and nitrogen atoms, except for the quadruple coordinated position on the surface of TiN and TaN, where there is a high degree of ionic bonding of silicon with surface atoms. Full article

Heptafluoropropyl methyl ether (HFE-347mcc3), as a lower-GWP (global warming potential) alternative to PFCs (perfluorocarbons), was used to etch SiO₂ contact holes. The etch profiles of the SiO₂ contact holes in HFE-347mcc3/O₂/Ar plasmas showed more bowing at lower flow rate ratios of HFE-347mcc3 to Ar, whereas more narrowing occurred at higher ratios. The measurements of the angular dependences of the deposition rates of fluorocarbon films on the surface of SiO₂ and the etch rates of SiO₂ showed that the shape evolution of contact-hole etch profiles at different HFE-347mcc3/Ar ratios was attributed to an increase in etch resistance and a decrease in etch ability of the sidewalls of the contact hole with the increasing HFE-347mcc3/Ar ratio. This resulted in determining the optimum ratio of HFE-347mcc3 to Ar to achieve the maximum anisotropy of the contact hole etched in HFE-347mcc3/O₂/Ar plasmas. By carefully selecting the specific flow rates of HFE-347mcc3/O₂/Ar (9/2/19 sccm), a highly anisotropic and bowing-free SiO₂ contact hole, with a 100 nm diameter and an aspect ratio of 24, was successfully achieved. Full article

This study addresses the need for effective rejuvenators in asphalt concrete mixtures containing Vacuum Tower Bottom (VB) binder, a by-product of petroleum refining. We investigated the use of a softening rejuvenator, comprising Carnauba (5.5%), Soybean oil (3%), water (81%), surfactant (1.5%), and additive (3%) from a Korean refining company, to mitigate the brittleness of VB binder. Laboratory experiments were conducted to compare the performance of the modified binder with the original hardened binder. The results showed that adding the rejuvenator improved the properties of the VB binder. Optimal asphalt grades were achieved with a 2% content of the softening additive in the VB binder. The rejuvenator enhanced moisture resistance, leading to settlements comparable to the control asphalt. Settlements after 20,000 load repetitions were 11.49 mm for the modified mixture, which were slightly better than the control material at 12.44 mm. Moisture stripping points occurred at around 16,000 cycles for the modified mixture, while the control material experienced them at approximately 13,000 cycles. Under freeze-thaw cycles, the modified mixture exhibited enhanced durability compared to the control mixture. The control mixture experienced a significant increase in rutting value of approximately 59.7% (from 12.4 mm to 19.7 mm), while the modified mixture showed a relatively lower increase of approximately 37.4% (from 11.5 mm to 15.8 mm). Additionally, the modified VB mixture demonstrated approximately 7.8% higher dynamic modulus at lower temperatures, indicating improved mechanical properties. It also displayed superior fatigue crack resistance, with a fatigue life of 18,385 cycles compared to 15,775 cycles for the control asphalt. Field results confirmed that the VB asphalt mixture with the rejuvenator achieved comparable site compactness to the control mixture, indicating successful compaction performance. These findings highlight the rejuvenator’s efficacy in mitigating binder stiffening and restoring the original state of aged asphalt binders. Full article

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. Full article

Multinary chalcogenides with Kesterite structure Cu₂ZnSn(S,Se)₄ (CZTSSe) are a prospective material base for the enhancement of the photovoltaics industry with abundant and environmentally friendly constituents and appropriate electro-physical properties for building highly efficient devices at a low cost with a short energy pay-back time. The actual record efficiency of 13.6%, which was reached recently, is far below the current isostructural chalcopyrite’s solar cells efficiency of near 24%. The main problems for future improvements are the defects in and stability of the Kesterite absorber itself and recombination losses at interfaces at the buffer and back contacts. Here, we present an investigation into the rapid thermal annealing (RTA) of as-electrodeposited thin films of Cu₂ZnSnS₄ (CZTS). The treatment was carried out in a cold wall tubular reactor in dynamic conditions with variations in the temperature, speed and time of the specific elements of the process. The effect of annealing was investigated by X-ray diffractometry, Raman scattering and Scanning Electron Microscopy (SEM). The phase composition of the films depending on treatment conditions was analyzed, showing that, in a slow, prolonged, high-temperature process, the low-temperature binaries react completely and only Kesterite and ZnS are left. In addition, structural investigations by XRD have shown a gradual decrease in crystallite sizes when the temperature level and duration of the high-temperature segment increases, and respectively increase in the strain due to the formation of the phases in non-equilibrium conditions. However, when the speed of dynamic segments in the process decreases, both the crystallite size and strain of the Kesterite non-monotonically decrease. The grain sizes of Kesterite, presented by SEM investigations, have been shown to increase when the temperature and the duration increase, while the speed decreases, except at higher temperatures of near 750 °C. The set of experiments, following a scrupulous analysis of Raman data, were shown to have the potential to elucidate a way to ensure the fine manipulation of the substitutional Cu/Zn defects in the structure of CZTS thin films, considering the dependences of the ratios of Q = I₂₈₇/I₃₀₃ and Q′ = I₃₃₈/(I₃₆₆ + I₃₇₄) on the process variables. Qualitatively, it can be concluded that increases in the speed, duration and temperature of RTA lead to increases in the order of the structure, whereas, at higher temperatures of near 750 °C, these factors decrease. Full article

The energy of the sputtered atoms is important to control the microstructure and physical properties of thin films. In this work, we used the SRIM program to simulate the energy of sputtered atoms. We analyzed the energy distribution functions (EDFs) and the average energies of the atoms in different spatial directions for a range of target materials and Ar ion energies. The results were compared to the analytical equations for EDFs derived by Sigmund and Thompson and with experimental data from the literature. The SRIM simulations give realistic EDFs for transition metals, but not for elements lighter than Si. All EDFs show a low-energy peak positioned close to one-half of the surface binding energy and a high-energy tail decreasing as approximately E⁻². We analyzed the characteristics of EDFs, specifically, the position of low- and high-energy peaks, FWHM, and the energy tail, with respect to the ion energy and position of the element in the periodic table. The low-energy peak increases with atomic number for elements within each group in the periodic table. Similar changes were observed for FWHM. For the period 5 and 6 elements, additional broad high-energy peaks were observed at emission angles above 45° when sputtered by Ar ions with 300 eV and also in some heavier elements when bombarded by 600 eV and 1200 eV ions. The transition metals in groups 4, 5, and 6 in periods 5 and 6 have the highest average energies, while the lowest average energies have elements in group 11. The results of simulations show that the average energies of sputtered atoms were inversely proportional to the sputtering yield, i.e., the higher the sputtering yield, the lower the average energy of sputtered atoms. We established an empirical equation for transition metals to estimate the average energy of sputtered atoms from the sputtering yield. The angular distribution of the average atom energy depends on the atomic number. Transition metals with 22 < Z < 72 have an anisotropic energy distribution, with the highest average energies in the 40°–70° range. For the elements in group 11, the angular distribution of the average energies is more isotropic. Full article

The association of the V-prep and a resin-modified glass ionomer cement (RMGIC) has shown to be a suitable alternative for the orthodontic bracket bonding procedure in vitro. The aim of this study was to evaluate over eighteen months the clinical bonding failure and survival rates of the conventional bonding technique using the Transbond XT (3M Unitek, Monrovia, CA, USA) and the RMGIC Fuji Ortho LC (GC Corporation, Tokyo, Japan) prepared with the V-prep. Therefore, one operator using the straight-wire technique bonded two hundred metallic brackets to upper and lower premolars of twenty-five patients requiring an orthodontic treatment. The randomized trial was a single-blind design in a split-mouth comparison. Each patient was randomly allocated one of the two bonding systems for each premolar on each side of the mouth. The bonding and rebonding techniques were standardized throughout the trial and bond failure was recorded each month for a period of eighteen months. The survival rates of the brackets were estimated by Kaplan–Meier and log-rank test (p < 0.05). A total of 200 orthodontic brackets were included in the study with a significant lower failure rate of 9.0% for the V-prep and RMGIC compared to 25.0% for the conventional bonding technique (p < 0.05). A higher survival rate was observed for the V-prep and RMGIC (16.36 months) over the conventional bonding technique (13.95 months) (p < 0.05). Lower premolar bonding failure was higher than upper premolar for both bonding techniques. The V-prep followed by RMGIC, with enamel surface protection abilities, can be used as an alternative bonding technique in an orthodontic treatment. Full article

At present, for micro-textured tools, the determination of the micro-texture placement area depends on the derivation of the cutting geometric model. The micro-texture distribution form applies geometric methods, and the research methods and accuracy are limited. Therefore, in this paper, the ball-end milling cutter is taken as the research object. Based on fractal theory, the morphology of the tool before and after wear is compared to determine the tool–chip contact area. The uniform-density micro-texture distribution model is established using the uniform distribution point theorem, and the synergistic mechanism of the edge and the micro-texture is revealed. The strength of the micro-textured tool with uniform density under the action of the edge is studied by simulation. Finally, the determination of the tool–chip contact area and the establishment of a uniform-density micro-texture model is realized. It is proved that the synergistic effect of the cutting edge and the micro-texture has a positive effect on the milling behavior of the tool. When comparing the non-edge and non-texture tools with the cutting-edge tools, the maximum strain and stress of the cutting-edge micro-textured tools increased by 12% and 30%, and 30% and 20%, respectively, without affecting the normal use of the tool. This research provides a new method for the design of micro-textured tools. Full article