Solid State Phenomena Vol. 379

Abstract: This study investigated the incorporation of lignin nanoparticles derived from black liquor (S-BLNAce) into polybutylene succinate (PBS) to enhance the antimicrobial and irradiation-shielding properties of PBS composite films for packaging applications. Black liquor, a by-product of paper industry, was utilized to produce nanolignin through acetone fractionation and anti-solvent precipitation techniques. PBS composite films with varying S-BLNAce concentrations (0.5–2.0%wt) were fabricated via blow-molding and evaluated for mechanical, irradiation-shielding, and antimicrobial properties. The addition of S-BLNAce nanolignin improved the tensile strength and modulus of PBS, particularly at lower concentrations, while slightly reducing elongation at break. Films with higher nanolignin content exhibited enhanced irradiation shielding, especially in the UV-A and UV-B regions, and demonstrated significant antibacterial activity against Escherichia coli and Staphylococcus aureus. These findings highlight the potential of nanolignin as a bio-based additive for developing high-performance, sustainable packaging materials, aligning with circular economy and sustainability goals.

Abstract: This study examines how infill percentage and infill pattern affect the compressive strength of 3D-printed High-Density Polyethylene (HDPE) parts using Fused Deposition Modeling (FDM). Specimens were printed with infill densities of 15%, 30%, 60%, and 100% across three patterns: honeycomb, grid, and triangular. Compression tests followed ASTM D695 standards. Results show that compressive strength increases significantly with higher infill percentages, with fully solid (100%) samples reaching up to 43.35 MPa. Among patterns, the honeycomb design consistently outperformed grid and triangular structures due to its efficient stress distribution. At lower infill percentages, pattern choice had a stronger impact, while at higher densities, the infill percentage became the dominant factor. These findings offer practical guidelines for optimizing strength and efficiency in applications such as aerospace, automotive, and healthcare.

Abstract: In₂O₃/ZnO/fluorine-doped tin oxide (FTO) photoanode was prepared by electrochemical anodization-hydrothermal approach and to assemble a visible light activated photocatalytic fuel cell (PFC) with CuO/Cu cathode. The as-fabricated electrodes were scrutinized using field-emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) and electrochemical impedance spectroscopy (EIS) analyses. The maximum power density and chlortetracycline hydrochloride (CTCH)-bearing aquaculture wastewater removal efficiency of In₂O₃/ZnO/FTO PFC treatment for 240 min were 0.3084 µW cm^-2 and 91.5%, respectively, which were much higher than that of PFC with ZnO/FTO photoanode (0.1805 µW cm^-2 and 67.5%, respectively). The spectacular performance of this PFC system was realized by the S-scheme heterojunction of the photoanode between In₂O₃ and ZnO/FTO, which boosted the segregation of photoexcited carriers and yielded powerful active radical species for the photoelectrocatalytic activity. This study can serve as reference for the devise and heterojunction establishment of highly effective electrodes of PFC with visible light response.

Abstract: The photoanodes of dye-sensitized solar cells (DSSCs) were studied. Industrial TiO₂ nanoparticles (P25) were used to form the active layer, and hollow ZnO nanoparticles (hollow ZnO) or ZnO powder particles were coated on top of the active layer to form the scattering layer. The hollow ZnO scattering layer helps increase the amount of dye adsorption as the surface area increases and the efficiency of incident light utilization due to high scattering characteristics. As a result, the light absorption of photoanodes with hollow ZnO was about 90% higher than that of DSSC with only TiO₂ film and about 25% higher than that of DSSC with ZnO powder as a scattering layer.

Abstract: In water splitting, high-performance electrocatalysts play an essential role in the oxygen evolution reaction (OER). This study focuses on preparing nanoflower-structured electrocatalysts by coating different amounts of Ni in NiCoFe double hydroxide (LDH) onto the NiCo₂O₄ surface on Ni foam (NF) using a hydrothermal method. The NiCoFe-LDH@NiCo₂O₄/NF electrocatalyst demonstrates excellent activity for OER, exhibiting low overpotential and good stability. The exceptional performance is attributed to the high electrochemically active surface area of ​​NiCoFe-LDH when combined with NiCo₂O₄. The optimal Ni_0.75CoFe-LDH@NiCo₂O₄/NF electrocatalyst demonstrates exceptional oxygen evolution reaction (OER) performance, with a low overpotential of 254mV at a current density of 50mA·cm⁻². It also shows excellent durability, with minimal overshot during overall water splitting stability tests. This study suggests developing highly efficient OER catalysts using ternary transition metals in the future.

Abstract: The paper presents a systematic approach to optimize the HVOF deposition technology of Al₂O₃ 40 TiO₂ coatings for the protection of components in the energy industry. Key performance factors evaluated include scratch resistance, surface roughness, and friction coefficient, given their importance for the intended applications. By means of a comprehensive experimental program using the Design of Experiment (DOE) method, the main HVOF process parameters were investigated, such as Fuel-to-Oxygen ratio (F/O), Stand-off Distance (SOD), and Powder Feed Rate (PFR), to identify optimal deposition conditions. Scratch resistance tests revealed that increasing the F/O and reducing the SOD significantly improved the tribological properties of the coatings. Surface morphology analysis through optical and electron microscopy confirmed that optimized HVOF parameters lead to dense coatings with low roughness and minimal defects, essential characteristics for components subjected to wear and severe friction. Additionally, tribological measurements demonstrated a significant reduction in the coefficient of friction for the optimized coatings. The obtained results demonstrate the HVOF technology’s capability to produce Al₂O₃ 40 TiO₂ coatings with superior properties for protecting energy industry components operating under severe conditions. The presented optimization approach can serve as a guide for best practices in developing new coating systems with enhanced performance.

Abstract: This paper focuses on the deposition and characterization of tungsten carbide (WC) hard thin films using the plasma jet deposition technique, with special emphasis on their hydroabrasive wear behavior. Tungsten carbide coatings are recognized for their exceptional properties such as high hardness, excellent wear and corrosion resistance, and chemical and thermal stability. The plasma jet deposition technology allows the formation of dense layers, well adhered to the substrate, with precise control over the thickness and microstructure of the deposited layer. The study analyzed process parameters, such as spray distance and particle velocity, which influence the microstructure and performance of the deposited layers. The characterization of the layers was carried out by methods such as scanning electron microscopy (SEM) and the composition was determined with the help of the EDX probe. The tribological properties of the WC layer were also investigated.

Abstract: This paper presents an in-depth spectroscopic analysis of Al₂O₃-40%TiO₂ coatings deposited via HVOF thermal spraying on a 10CrMo9.10 heat-resistant steel substrate. The study aims to correlate the optoelectronic and structural properties of the coatings with their composition and microstructure. Spectroscopic investigations revealed intense absorption in the visible (VIS) region due to electronic transitions from the valence band to the conduction band of the ceramic materials and high reflectivity in the ultraviolet (UV) region. These properties make the coatings particularly useful for protective systems in solar thermal power plants. The detailed characterization of the optical properties of the Al₂O₃-40%TiO₂ coatings obtained through HVOF technology was made possible by corroborating spectroscopic results. These insights are essential for understanding the mechanisms that govern the performance of these coatings in protective applications under high temperatures and aggressive environments.

Abstract: Using high-strength steels as substrates for hardfacing has become more and more influential over the years. The usage of high-strength steels started with S690QL steel, but nowadays the S1100QL is also applied as a substrate. Several applications can be found in the construction and demolition fields where the dynamic loading occurs beside the abrasive loading. To withstand this complex loading, the high-strength steel substrates are hardfaced by special welding wires with good wear resistance. In case of welding this type of material requires pre-heating especially for thick plates and requires very strict welding technology and necessary to adjust the right t8/5 cooling time for good results. The pre-heating can be very costly in case of hardfacing because of the relatively large surfaces and production time is also increasing. Additionally, in case of S1100QL steel, only softening happens in the heat-affected zone, and in most cases, it is necessary to minimize this effect to reach the highest strength. Previous investigations highlighted the effect of heat input on the softening, but pre-heating is always applied. Recent research focused on the need for pre-heating during hardfacing on S1100QL steel. Specimens were made with and without pre-heating using the same technological parameters and circumstances. Macroscopic and microscopic tests were performed on the hardfaced specimens to check the dimensional and microstructural differences. Then Vickers hardness measurements are performed on several points which resulted hardness maps on both cases. The subzones of heat-affected zones are identified with the help of hardness maps, and a comparison was made. The hardness results show remarkable differences in different subzones between the pre-heated and not pre-heated specimens. Hardened parts are not found in the heat-affected zones, but less softening happens with the not pre-heated technology.