Abstract: The present work, optimization of ceramic-based composite WC (Co, Ni) welds by laser cladding through the response surface methodology based on finite element analysis. The heat distribution and temperature field of laser melted WC(Co,Ni) ceramic coatings were simulated using ANSYS software which allowed the computation of the distribution of residual stresses. The results show that the isotherms in the simulation of the temperature field are elliptical in shape, and the isotherms in front of the moving heat source are dense with a larger temperature gradient, and the isotherms behind the heat source are sparse with a smaller temperature gradient. In addition, the observed microstructural evolution shows that the domains of the melting zone of WC(Co,Ni) are mainly composed of unmelted carbides, dendritic, rod-like, leaf-like, net-like, and smaller agglomerates of carbides in which the W content of unmelted carbides exceeds more than 80%, and the C content is about 1.5-3.0%, while the grey areas are composed of WC, Co, and Ni compounds. Based on the regression model, a quadratic model was successfully constructed. A three-dimensional profile model of the residual stress behavior was further explored. The predicted values of RSM-based FEA model for residual stress are very close to the experimental data, which proves the effectiveness of model in improving the residual stress by laser cladding .

Abstract: Uniformity in material coating is not only essential for ensuring durability and long-term reliability but also for reducing costs, optimizing resources, and maintaining high-quality standards in industrial applications. Zinc phosphate is notable for coating steel surfaces due to its excellent corrosion resistance and adhesion properties in various industries. This study investigates the optimal flow rate of a diaphragm pump for achieving effective and uniform coating of a steel cylinder. The coating uniformity was assessed using Scanning Electron Microscopy (SEM), focusing on layer thickness and elemental composition. A range of flow rates was analyzed to determine their influence on coating quality and regularity, with Energy Dispersive Spectroscopy (EDS) revealing the distribution and homogeneity of the applied layer. The results identified a flow rate of 30 L/min as optimal, as it minimized surface defects and ensured consistent thickness across the cylinder. This study provides valuable insights for optimizing industrial coating processes, contributing to improved efficiency and reduced resource waste.

Abstract: A one micron thick pure zinc oxide (ZnO) and nitrogen doped zinc oxide (N-ZnO) films, were fabricated on p-type, pristine (non-porous) and porous gallium nitride (GaN) substrates using a radio frequency (RF) sputtering technique at room temperature. The doping medium is nitrogen gas, which has a flow rate that ranges from 0 to 10 sccm (0 sccm refers to pure ZnO). Ultraviolet (UV) assisted photo electrochemical etching technique was employed to etch the wafer surface and develop porous GaN substrate. High-quality ZnO films were grown with ZnO powder as the target material under vacuum conditions. The X-ray diffraction (XRD) analysis confirms that the films grown on GaN possess a hexagonal wurtzite structure. For N-ZnO films, the UV-visible cut-off wavelength shifts towards the blue region. The root mean square (RMS) roughness of N-ZnO films, measured using atomic force microscopy (AFM), was found to decrease with increasing N-doping concentration. The lowest roughness value of 1.1 nm was observed for the 10 sccm sample, while the highest roughness of 3.4 nm was recorded for the pure ZnO film. The N-ZnO films was found to exhibit p-type conductivity as determined by Hall measurements using Van der Pauw method and the higher value of carrier concentration obtained for the nitrogen gas flow rate of 10 sccm, was 7.99 x 1018 cm-3.

Abstract: Periodically modulated optical coatings, fabricated by depositing conformal films on modulated substrates, offer unique capabilities for spectral and spatial filtering of light. However, conventional deposition methods often do not achieve the required replication and conformality on submicron-size structured surfaces. In this paper, we compare various thin film deposition techniques, including electron beam evaporation, atomic layer deposition, and ion beam sputtering, to evaluate their ability to control multilayer coating growth on periodically modulated substrates. Our study demonstrates that both single-layer and multilayer coatings produced by ion beam sputtering effectively replicate the initial geometry of structured surfaces, thereby enhancing optical performance.

Abstract: Metallic tubes are widely used in industrial applications. However, the internal smoothness and chemical resistance of metallic tubes are often major concerns. In contrast to the widely studied large-diameter metallic tubes (typically > 4 cm internal diameter) commonly investigated for surface modifications in industrial applications, we have focused on modifying the internal sur-faces of much smaller SS304 tubes (0.6 cm internal diameter) using nitrogen and argon PIII, as well as acetylene PIII&D. This study demonstrated that high-quality internal surface modifica-tions can be achieved with a straightforward setup and appropriate analysis techniques, even in tubes of industrial relevance with such small dimensions. In addition to gaining insights into the characteristics of hollow cathode (HC) and dielectric barrier (DB) discharges in small-diameter tubes, we found that Ar-PIII can partially mitigate the poor surface quality of as-received tubes. The addition of an N-PIII step further enhanced the internal surface, resulting in a smoother fin-ish with fewer trapped impurities. Moreover, acetylene PIII&D enabled the rapid deposition of a thick (>300 μm) Glassy Carbon film. These findings highlight the potential of these techniques for various plasma-related applications and industrial processes, offering promising avenues for future development.

Abstract: The rapid growth of industrial activities has increased environmental pollution, and so-lar-driven heterogeneous photocatalysis using TiO2 has emerged as a promising solution. However, its wide bandgap limits its efficiency, prompting research into various optimi-zation strategies. One of these approaches is surface functionalization. Thus, this study investigates the adsorption of CuSO4 on the anatase TiO2 (101) surface using density func-tional theory calculations. The adsorption process induced a magnetic moment of 0.97 µB and a slight reduction in overall bandwidth. A preferential adsorption geometry pattern with an energy of -4.31 eV was identified. Charge transfer analysis revealed a net transfer from the TiO2 surface to the CuSO4 molecule, with increased net atomic charges for atoms involved in new chemical bond formation, indicating a chemisorption process. These electronic structure modifications are expected to influence the electronic and catalytic properties of the material. The findings provide insights into the CuSO4 adsorption mechanism on anatase TiO2 (101) surface and its impact on the properties of the material, contributing to a deeper understanding of this system.

Abstract: The reflectance (R) of linear and circular micro-gratings on c-plane sapphire Al2O3 ablated by a femtosecond (fs) laser, were spectrally characterised for thermal emission ∝ (1 − R) in the mid-to-far infrared (IR) spectral range. An IR camera was used to determine the blackbody radiation temperature from laser patterned regions, which showed (3 − 6)% larger emissivity dependent on the grating pattern. The azimuthal emission curve closely followed the Lambertian angular profile ∝ cos θa at the 7.5-13 µm emission band. The backside ablation method on transparent substrates was employed to prevent debris formation during energy deposition as it applies a forward pressure of > 0.3 GPa to the debris and molten skin layer. The backside ablation maximises energy deposition at the exit interface where the transition occurs from the high-to-low refractive index. Phononic absorption in the Reststrahlen region 20–30 µm can be tailored with the fs-laser inscription of sensor structures/gratings.

Abstract:

Compositing and hybridizing compounds is a generally accepted route to making new materials that perform better than the individual components taken separately. Herein, we describe a new electrochemical route for constructing hybrid materials from Polypyrrole (PPy). In this context, thin films of silica layer (Si) deposited by electro-assisted on a flexible ITO (f-ITO) surface modified by diazonium salt (f-ITO-NH2) were covered with an adhesive layer of polypyrroles. Deposition periods ranging from 20 to 45 seconds produce more electroactive silica layers. The electrochemical method confirmed the growth of a silica layer on the surface of the f-ITO-NH2 electrode. The different flexible electrodes were characterized by XPS, by electrochemical and scanning electron microscopy (SEM), which showed the central role of the diazonium chemical interface in the development of PPy on the silica layer. According to cyclic voltammetric studies, altering the f-ITO surface with diazonium salts produces PPy-Si polymers with more conductivity than a comparable coating without integrated treatment. This work demonstrates the power of a subtle combination of diazonium coupling agents on f-ITO, silica layer, and conductive polymers (f-ITO-NH2-Si-PPy) to design high-performance electrochemical materials.

Abstract: In the present work, a study of the structural defects in HfO2 thin films deposited by dip-coating on p-type silicon substrates treated under different conditions, such as air-annealing, ultraviolet irradiation, and simultaneous annealing-UV irradiation, is presented. HfO2 thin films were analyzed by grazing incidence X-ray diffraction, Raman spectroscopy, optical fluorescence, atomic force microscopy, and UV-Vis diffuse reflectance. Films treated at 200 ºC and 350 ºC present peaks corresponding to monoclinic HfO2. After UV treatment, films became amorphous. The combination of annealing at 350 ºC with UV treatment does not lead to crystalline peaks, suggesting that the UV treatment causes extensive structural damage. Fluorescence spectroscopy and UV-Vis spectroscopy suggested that films present oxygen vacancies as the main structural defects. A reduction of oxygen vacancies after a second thermal treatment was observed, but in counterpart, after UV irradiation, fluorescence spectroscopy indicates that more defects are created within the mobility gap, irrespectively of the simultaneous annealing at 350 ºC. An electronic band diagram was proposed assigning the observed fluorescence bands and optical transitions. The results suggest that the electronic structure of HfO2 films can be tailored with a careful choice of thermal annealing conditions along with the controlled creation of defects using UV irradiation, which would open the way to multiple applications of the materials either in microelectronics and photocatalytic/electrocatalytic applications such as photodegradation and hydrogen generation.

Abstract: Coating disk-shaped materials on the bottoms of containers has become a highly effective method for tribocatalysis enhancement. Presently, the effects of Ti coatings on the tribocatalytic degradation of organic dyes by CdS nanoparticles have been systematically studied. For both 50 mg/L rhodamine B (RhB) and 20 mg/L methyl orange (MO) solutions, the tribocatalytic degradation by CdS nanoparticles was dramatically enhanced in Ti-coated beakers than in as-received glass-bottomed beakers, with the degradation rate constant increased by 4.77 and 5.21 times, respectively. Moreover, for tribocatalytic degradation of MO using CdS, two quite different MO degradation modes have been identified between Ti and Al2O3 coatings. Electron paramagnetic resonance (EPR) spectroscopy analyses showed that more radicals were generated when CdS nanoparticles rubbed against Ti coating than glass bottom, and boron nitride nanoparticles had been employed to verify that the enhancement associated with Ti coatings resulted from the interactions between Ti and CdS. These findings underscore the importance of catalysts and coating materials selection in tribocatalytic systems, offering valuable insights for the development of efficient environmental purification technologies.

Abstract: High entropy alloys are being increasingly investigated for their excellent combination of properties like strength, ductility, and significant low temperature fracture toughness. In the present work, the quinary equiatomic FeNiCoCrCu alloy is studied for its sputter deposition over a [001] nickel substrate using molecular dynamics simulations, described by the embedded atom method. The influence of annealing on the mechanical properties of the HEA coating is studied using nanoindentation with a virtual spherical indenter of diameter 25Å to an indentation depth of 25Å. The alloy is observed to undergo Transformation Induced Plasticity (TRIP) deformation – with activation and annihilation of stacking faults.

Abstract: This study investigates the enhancement of thermal durability in multilayer yttria-stabilized zirconia (YSZ) thermal barrier coatings (TBC) with porosity-controlled structures. Conventional single-layer YSZ and multilayer TBCs with dense- and porous-layers were fabricated by air plasma spraying and the TBC specimens were conducted to furnace cyclic testing. The single-layer TBC suffer from catastrophic delamination under cyclic thermal loading, driven by the mismatch in thermal expansion, while multilayer TBCs exhibited significant increase in thermal durability by up to 50%. Relevant delamination mechanism was suggested with microstructural analysis, showing the multilayer structure effectively relived residual stresses by forming horizontal cracks, thereby mitigating crack propagation. This study emphasizes that the multilayer design in TBC with controlled porosity significantly enhances thermal durability, improving the operational lifespan of gas turbine hot components.

Abstract: Nowadays, the development of eco-friendly paint formulations is part of the transition process to more sustainable materials, which involves many industrial fields such as offshore and shipbuilding where the deterioration of steel in seawater is a key factor. This article aims to produce suitable innovative coatings and test their protective action on DH 36 steel plates. Commercially available SiO2 and TiO2 were covalently modified with amino groups allowing two organic-inorganic hybrid materials for the immobilization of iron sites. The obtained powders were characterized by thermogravimetric analysis, N2 physisorption, X-ray diffraction, and X-ray photoelectron spectroscopy. Fe-based solids were used as filler for the design of ecological paint formulations which, in turn, were applied on the surface of metal prototype plates. The surface properties of the resulting coatings were examined by determination of thickness, water wettability, roughness, and cross-cut adhesion tests (before and after degradation test in seawater according to ASTM D 870-97 standard). Preliminary tests of the microbiological activity of the iron amino functionalized materials were carried out monitoring, as proof of concept, the growth of some bacterial strains through measurements of optical density.

Abstract: Driven by the effects of global warming and environmental pollution from fossil fuel use, the transition towards renewable energy sources, such as wind and solar power, is gaining momentum. Yet, photovoltaic systems encounter critical issues, primarily due to soiling or dust accumulation, which can diminish power efficiency by 20-40% and raise maintenance expenses. Therefore, this study aims to develop a durable, transparent, environmentally friendly, and cost-effective anti-dust coating for photovoltaics, evaluating its potential to maintain PV power performance under harsh environmental conditions. The coating was applied using the dip-coating method, followed by heat curing to improve adhesion. Microstructural analysis using XRD, SEM, and EDS showed that the coating consists of SiO2 nanograins. The one-month current-voltage (I-V) measurement test showed that coated samples had a higher Maximum Power Point by 8.7% and Open Circuit Voltage by 5.3% than uncoated ones. Transmittance evaluations over seven months showed that coated samples maintained a high level of transparency at 94% under clean conditions. Coating durability was confirmed through abrasion tests, where the coating withstood 30 cycles, a figure among the highest recorded for silicon dioxide coatings. The UV resistance and chemical stability tests further demonstrated robustness against environmental stressors. Additionally, a notable increase in cost efficiency ($1.5/kg) over conventional cleaning methods was observed, attributed to the coating's low-maintenance nature. In conclusion, this coating significantly benefits the solar energy industry by maintaining photovoltaic panel efficiency and substantially reducing cleaning costs, bridging the gap between innovative research and practical applications.

Abstract: We report the formation of multi-walled carbon nanotubes (MWCNTs) through the interaction of an atmospheric-pressure plasma jet, generated via a capillary discharge, with a graphite surface. This surface-modifying discharge was established in a brief air gap between the cathode and ignition electrode, manipulated across varying discharge power levels. Notably, the structural properties of MWCNTs on the graphite anodes demonstrated a clear dependence on discharge power. Utilizing scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy, we observed a progression toward disordering in the nanotubes alongside the emergence of graphitized clusters with increasing discharge energy. The formation of relatively defect-free MWCNTs at minimal discharge energy presents an opportunity for their synthesis with low energy consumption of 4.7 kJ/cm2. The suggested energy-efficient, rapid and straightforward technique for tailoring MWCNT formation significantly reduces the reliance on complex and expensive instrumentation, presenting a promising pathway for effective surface modification with potential applications in electronics, gas sensors, and water treatment.

Abstract: Biomimetic surfaces with low surface energy have garnered significant interest due to their exceptional properties such as self-cleaning, anti-fouling, and non-stick characteristics. These surfaces hold substantial potential for a wide range of applications in fields including food industry, healthcare, and energy sectors. We have identified that the surface of mushrooms possesses an array of microconical structures, which endows the mushroom surface with self-cleaning properties. Inspired by this low-adhesion characteristics of the mushroom surface, we have designed and developed a flexible, low-adhesion biomimetic surface. Utilizing laser direct writing and spot shaping techniques, we fabricated a controllable array of microconical structures on a template substrate. The biomimetic replication process was then employed to obtain a microstructured surface based on polydimethylsiloxane (PDMS). Subsequent fluorination grafting was performed on the surface to create a mushroom-inspired superhydrophobic functional surface. Experimental results indicate that this surface exhibits ultra-low adhesion to deionized water, milk, coffee, and other liquids. Additionally, this surface possesses a flexible overflow effect and ultra-low adhesion properties with high robustness. We believe that this process can offer new insights into the biomimetic design of flexible low-adhesion surfaces.

Abstract:

Paper-based artworks are prone to natural aging processes driven by chemical and biological mechanisms. Numerous cleaning, disinfecting, and protective treatments have been developed to mitigate deterioration and prevent irreversible damage. In this context, the application of hydrogels as support materials has gained widespread attention due to their efficacy in enabling minimally invasive treatments. In the present study, we investigated the use of poly(acrylic acid)/TiO₂ composite hydrogels both as cleaning agents and protective coatings to shield paper from the detrimental effects of ultraviolet (UV) radiation. To evaluate the efficacy of these treatments, we employed a diagnostic protocol previously developed to differentiate between hydrolytic and oxidative aging processes, based on Raman spectroscopy imaging. Our findings demonstrate that papers coated with poly(acrylic acid)/TiO₂ composite hydrogels exhibit enhanced stability and improved resistance to degradation compared to uncoated samples.

Abstract:

Objective: This study focuses on the synthesis and analysis of the morphology of CsSnI3 crystals and films based on CsI and SnCl2 solutions. The aim of this approach is to synthesize air-stable perovskites and prevent phase transitions of tin-containing perovskite, where previous studies have often reported its rapid oxidation when dissolved in dimethyl sulfoxide. Methods: CsSnI3 crystalline films were obtained from CsI and SnCl2 solutions, in which deionized water and ultrapure ethanol were used for their dissolution. Dissolution and mixing were performed at room temperature. High-purity CsI (99.99%) and SnCl2 (99.99%) powders were used to obtain solutions. To obtain a homogeneous CsSnl3 solution, the SnCl2 solution was added dropwise to the CsI solution and stirred on a magnetic stirrer at 900 rpm. The resulting solution was then applied to FTO substrates heated on a hotplate without spin coating. The samples were heated to temperatures from 60 0C to 130 0C, where, depending on the rate of evaporation of the liquid, the process of formation of crystalline and thin-film structures was controlled. Results: Stable CsSnI3 films were obtained. SEM and X-ray diffraction analyses of the obtained cesium tin triiodide films deposited on conventional FTO glass substrates were performed. X-ray diffraction patterns of synthesized perovskite crystals and films were obtained. Conclusion: The synthesized CsSnI3 perovskite thin films retained their black perovskite phase for more than 4 months, indicating their long-term stability. Based on the results and long-term stability performance, it can be concluded that the black phases of CsSnI3 are suitable for various applications such as photovoltaic devices.

Abstract: The effect on the physical, mechanical, and antibacterial properties of films composed of alginate-chitosan with the incorporation of oregano (EOO) or thyme (EOT) essential oils was evaluated. The results indicated that the incorporation of essential oil increased the thickness of the films, in addition to evidencing a significant effect on the colour variation towards the yellow tone, especially in the b* factor. On the other hand, the incorporation of essential oil significantly decreased the tensile strength, simultaneously increasing elasticity. Regarding antibacterial capacity, as the concentration of essential oil increases, the antibacterial capacity also increases. On average, the increase from 1% to 3% of EOO increased the antimicrobial capacity against Gram-negative and Gram-positive bacteria. These results suggest that films with the addition of oregano and thyme essential oils can be promising for food packaging applications with the ability to improve food safety and increase product shelf life by achieving functional packaging characteristics.

Abstract: Metal organic frameworks (MOFs) have become a highly usable system in various sectors because of their highly ordered structure and high porosity providing them with high storage capacity. But their use is sometimes forbidden in the food industry due to the presence of some organic compounds which have undesirable effects. Cyclodextrins which are considered GRAS (Generally Recognized as Safe) by FDA comes as a very good alternative to previously used compounds for the development of the MOF’s to be used in food packaging industry especially in the packaging sector. These cyclodextrin MOF does possess edible, biocompatible as well as biodegradable characteristics and due to these reasons they have gained attentions from researchers in the food industry. In this review we focus on the recent advancements in the field of CD MOF’s. We have emphasized on the synthesis of these MOF’s through different techniques, formations of their inclusion complex with bioactive compounds and their characterization. Finally, we discussed on the use of CD MOF as a carrier for various highly volatile bioactive compounds and their ability to increase the solubility and stability of these bioactive compounds.