Search Results (1,481)

To address the challenge of efficient catalytic elimination of carbon monoxide (CO) generated from spontaneous coal combustion in goaf and blasting operations in underground coal mines under low-velocity laminar flow conditions, we propose a perforated spiral-insert catalytic tube. The design inserts a spiral vane with surface micro-holes into a straight tube; the vane surface and internal pore walls are coated with a CuMnOx catalyst. A porous medium equivalent model describes the flow and catalytic reaction characteristics in the perforated region. A three-dimensional Computational Fluid Dynamics (CFD) model coupling flow, mass transfer, and surface catalytic reactions is developed. After grid independence verification, three sets of L9 orthogonal experiments systematically investigate the effects of inlet velocity, helix pitch, vane height, opening ratio, and pore diameter on CO conversion and flow resistance. Range analysis, variance analysis, and the comprehensive performance factor are used for multi-objective optimization. $PEC$ results show that inlet velocity is the primary factor affecting both conversion and comprehensive performance, and its dominance is independent of the number of vanes. At a low velocity of 0.2 m/s, the four-vane configuration achieves a maximum conversion of 51.07%. For a balanced trade-off between conversion and flow resistance, four vanes with a high opening ratio, large pore diameter, and large helix pitch yield the best comprehensive performance. If low resistance is the primary goal, two vanes with a high opening ratio achieve a resistance of only 0.29 Pa and a per-unit-resistance conversion efficiency of 97.72 Pa⁻¹. A further predicted optimal combination is validated by simulation, achieving a conversion of 64.96%, confirming the effectiveness of the parameter optimization. Under low-velocity conditions, the flow resistance of this design is only about 0.3–1.3 Pa, allowing passive operation using the natural negative pressure of the extraction pipeline. The design offers modular replaceability of the catalyst insert and operates without external power input beyond the natural negative pressure of the pipeline under the simulated low-velocity conditions, providing a theoretical basis and parameter optimization method for in situ CO catalytic elimination in coal mines. Full article

We investigated the possibility of developing super austenitic stainless steel Avesta SMO 254 X1NiCrMoCuN20-18-7 (EN 10088-4) and austenitic stainless steel X15CrNiSi25-21 (EN 10095) coated with SiC, resulting in the obtainment of a Metal Matrix Composite (MMC) by additive manufacturing (AM) for the upgrade of nozzles for sulfur recovery thermal reactors. One layer of the MMC targets the outer surface of the part that is in constant contact with the flame and the area is subjected to high friction erosion. The Directed Energy Deposition Laser (DED-LB) method has made it possible to produce a high strength-to-weight ratio. The aim is to engage lower-cost material with similar thermal stability and durability in extreme conditions. The robotic unit used for the application allowed for computer control of the positioning, feeding of the SiC particles inside the shielding gas and deposition in the molten pool. After the solidification process, visual testing (VT) and ultrasonic testing (UT) were applied for non-destructive evaluation, checking for disbonding and subsurface imperfections. Then, samples were tested with microhardness measurements, bond strength, microcracking detection, porosity, interface zone assessments and microstructural analysis. The process achieved 0.4 to 0.7 KJ mm⁻¹ heat input with no defects and the intended nozzle surface passed UT and VT. Controlled parameters provided strong metallurgical bonding. Full article

The guqin is a traditional Chinese musical instrument with a long history, and lacquering is a key step in modern guqin fabrication. Nevertheless, traditional raw-lacquer coatings on guqin soundboards possess poor wear and weathering resistance. During frequent use and varied storage conditions or in certain environments, these coatings are susceptible to bacterial contamination, as well as photothermally induced embrittlement and aging. In this study, while retaining the essential features of the traditional lacquering process, candidate modified raw-lacquer topcoats with potential for application to modern guqin soundboards were prepared. Natural raw lacquer was used as the matrix, methyltrimethoxysilane (MTMS) as the crosslinking agent, copper-loaded zeolite (Cu(II)-nZ) as the antibacterial agent, and boron nitride (BN) nanosheets together with nano-ZnO as functional modifiers. The modified lacquer coatings showed improved antibacterial property, wear resistance, interfacial adhesion, and UV aging resistance. Although Cu(II)-nZ addition was accompanied by a decrease in surface gloss, the resulting lower-gloss appearance may be compatible with the subdued visual character of traditional guqin finishes. The modified raw-lacquer coatings also showed low hemolysis in vitro. Collectively, compared with conventional raw lacquer, the modified raw-lacquer coatings exhibit improved material-level protective performance. They are worthy of further investigation as potential topcoats for guqin soundboards, with acoustic and vibrational validation to be performed. Full article

Compared with bare copper wire, palladium-coated copper (PCC) wire is widely used in microelectronic packaging due to its improved oxidation resistance and enhanced reliability. However, the formation mechanism of free air balls (FABs) and the redistribution behavior of Pd during the electronic flame-off (EFO) process, particularly under different Pd coating thicknesses and processing conditions, have not yet been fully understood. In this work, four types of 1 mil PCC wires with Pd coating thicknesses of 60, 80, 100, and 120 nm were systematically investigated to study the influence of EFO parameters on FAB morphology and Pd redistribution behavior. SEM, FIB, and EDS analyses were employed to provide experimental insights into the coupled relationship between transient thermal input, internal pore distribution and elemental segregation evolution, and Pd redistribution behavior. The results show that the preferred FAB morphology is obtained at 54 mA and 580 μs, with a diameter-to-wire ratio of approximately 2. With increasing Pd coating thickness, the exposed copper area on the FAB surface decreases from 13% to 6%, while the Pd-deficient region gradually shifts toward the bottom of the FAB. This study provides experimental insights into the Pd redistribution behavior during FAB formation under different EFO conditions, which may contribute to the optimization of Pd-coated Cu bonding wires. Full article

Tungsten nitride (WN) coatings were deposited on copper substrates by reactive direct current magnetron sputtering using deposition times of 15, 30, 45, and 60 min. The influence of deposition time on the structural, morphological, and electrical properties of the coatings was systematically investigated. WN coatings with thicknesses increasing from approximately 0.45 to 1.60 μm were obtained as the deposition time increased. Energy-dispersive X-ray spectroscopy confirmed the presence of W and N in the coating region, while X-ray diffraction showed diffraction features consistent with a crystalline hexagonal δ-WN phase with a dominant {110} preferred orientation for all samples. Increasing deposition time was accompanied by a decrease in the lattice parameter from 2.934 to 2.922 Å and in the relative lattice strain from 0.014 to 0.010. Atomic force microscopy showed that coatings deposited for 15 and 30 min reduced the initial surface roughness, whereas longer deposition times promoted the development of larger surface features and increased roughness. Electrical impedance measurements showed a strong frequency-dependent response. Electrical impedance exhibited a pronounced frequency dependence. At the 1000 kHz range, the impedance magnitude was approximately 0.54 Ω, 0.43 Ω, 0.45 Ω, and 0.43 Ω for coatings deposited for 15, 30, 45, and 60 min, respectively. The electrical response was correlated with the evolution of lattice strain and structural characteristics, although the present data not establish a unique charge-transport mechanism. These findings indicate that deposition time is an important parameter for tailoring the structural and electrical response of WN coatings for conductive and protective applications. Full article

The present research investigates the optimization of ball burnishing (BB) process parameters to create regular lubricating grooves on multilayer connecting rod liners to prevent engine seizure. The study utilized a Taguchi L9 fractional orthogonal array to evaluate the impact of ball diameter, deforming force, and feed rate on the resulting groove widths. Statistical analysis (ANOVA) revealed that ball diameter is the primary driver of groove width variation, exhibiting a non-linear parabolic relationship where the diameter serves as a stabilizing threshold. While deformation force showed a steady linear progression in widening traces, higher feed rates were found to restrict localized plastic flow, resulting in narrower groove widths. For the bimetallic structure (steel back with AlSn20Cu coating), the research recommends tailoring forces to the specific layer—forces for the anti-friction layer and for the substrate to avoid structural destruction. Profilometry confirmed that the height of edge inflows directly correlates with groove depth, ranging from 6 to 30 μm. The optimized non-linear regression model developed in this study achieved an exceptionally high coefficient of determination (R² = 99.84%), ensuring precise predictive accuracy. Overall, these findings provide a robust framework for researchers to enhance the durability of heavy-duty engine components through controlled surface topography. Full article

In this work, we systematically investigate the effects of metal doping on the structural, electrical, and optical properties of spin-coated nanocrystalline ZnO thin films prepared by a simple acetate-based solution process. The incorporation of different metal dopants significantly modified the crystallographic, electrical, and photoluminescence properties of ZnO. Doping with alkali metals enhanced the photoluminescence efficiency and enabled amplified spontaneous emission, whereas Mg was the only dopant that produced a pronounced blue shift in the photoluminescence spectra. Lithium-doped ZnO exhibited a strong concentration-dependent electrical behavior, producing highly conductive n-type ZnO at a 1% doping level and p-type conductivity at an 8% concentration. Strong n-type conductivity was also achieved using low concentrations of Li and Na and higher concentrations of Al. In contrast, Fe-, Ni-, Cu-, and Pb-doped ZnO exhibited a substantial reduction in electrical conductivity accompanied by strong photoluminescence quenching, indicating enhanced defect-related carrier compensation. These results demonstrate that metal doping provides an effective approach for tailoring the structural, optical, and electrical properties of ZnO and offers a versatile route toward engineering ZnO-based layers for optoelectronic devices, transparent conductive contacts, photodetectors, solar cells, and ultraviolet laser applications. Full article

Nickel coatings were deposited onto the surfaces of red mud, Al₂O₃, and Fe₂O₃ particles via an electroless plating technique. The nickel-coated particles (1.5 wt.%) were subsequently incorporated into a ZL109 aluminum alloy matrix to fabricate three types of composites using a stir-casting process, followed by a T6 heat treatment consisting of solution treatment at 515 °C for 8 h, water-bath quenching at 90–100 °C, and artificial aging at 175 °C for 12 h. The microstructural morphology and phase identification were examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Furthermore, the high-temperature tensile properties of the fabricated alloys were evaluated at 350 °C and 400 °C. The results showed that the addition of 1.5 wt.% nickel-coated red mud led to a more uniform distribution of eutectic silicon and an increase in the content of the Al₅Cu₂Mg₈Si₆, Al₇Cu₄Ni, and Al₂Cu strengthening phases. These microstructural changes significantly enhanced the high-temperature tensile performance of the alloy. At 350 °C and 400 °C, the alloy reinforced with 1.5 wt.% nickel-coated red mud achieved tensile strengths of 97.8 MPa and 86.2 MPa, respectively. The combination of an appropriate amount of nickel-coated red mud and a suitable heat treatment process effectively improves the high-temperature stability and tensile properties of the ZL109 aluminum alloy, which could be attributed to the synergistic strengthening effect arising from the precipitation of high-temperature stable phases and the Orowan mechanism. Full article

In this work, a Fe-based amorphous coating (Fe₄₄Cr₁₈Mo₇Ni₄Cu₂B₂₀Si₃C₂) was fabricated via high-velocity oxygen fuel (HVOF) spraying, and the effect of annealing temperature on its microstructure, phase composition, and corrosion resistance in 3.5 wt.% NaCl solution was investigated. The as-sprayed (AS) coating exhibits an amorphous content of 85.71% and a porosity of 1.37%. Annealing at 540 °C (H540) reduces porosity to 0.98% without significant crystallization, whereas annealing at 640 °C (H640) and 740 °C (H740) triggers extensive crystallization (amorphous content drops to 24.18% and 19.20%), and porosity increases to 1.82% and 2.17%. Electrochemical tests show that corrosion resistance deteriorates progressively with increasing temperature. i_corr increases from 3.56 μA/cm² (AS) to 50.0 μA/cm² (H740), while R_p decreases from 8472 to 669 Ω·cm². EIS reveals that the AS coating is dominated by the inner barrier layer (R_b >> R_t), whereas annealing causes a drastic collapse of R_b (from 8.374 × 10⁴ to 5.011 Ω·cm²). This degradation is attributed to crystallization-induced grain boundaries and reduced effective Cr content, which impair passive film integrity and accelerate corrosion. Full article

Biofilm accumulation on orthodontic appliances is a recognized risk factor for white spot lesion formation and caries during treatment. Antibacterial surface modifications and coating strategies have been proposed as appliance-level preventive approaches. Studied interventions in the literature span true thin-film surface coatings, plasma-based and ion-implantation surface modifications, and bulk-incorporated antibacterial agents in appliance matrix materials. Yet the extent to which in vitro efficacy translates to clinically meaningful protection remains unresolved. This PRISMA-ScR-compliant scoping review searched PubMed/MEDLINE, Scopus, Web of Science, Cochrane Library, and Google Scholar, identifying 109 eligible studies: 96 in vitro, 8 in vivo animal studies and 5 clinical trials, covering brackets, archwires, clear aligners, bands, miniscrews, elastomeric ligatures, and removable appliances, some articles studied multiple types of appliances. In vitro studies consistently demonstrated significant reductions in bacterial adhesion and biofilm formation across all appliance types, with silver-based coatings and nitrogen-doped TiO₂ showing the broadest evidence base; combination systems (Ag/ZnO, CuO-ZnO) outperformed individual agents. The 13 in vivo and clinical studies provided limited but directionally supportive evidence: silver nanoparticle-incorporated acrylic retainers reduced S. mutans counts in a double-blind RCT, and silver-infiltrated tungsten material-maintained biofilm reduction after simulated two-year abrasion. Coating durability emerged as an important determinant of potential clinical translation. Surface-deposited thin-film coatings degraded substantially within one month of intraoral use, whereas substrate-integrated approaches showed greater longevity. This scoping review maps the current evidence landscape, identifies coating durability and clinical endpoint validation as critical gaps, and prioritizes silver-based and nitrogen-doped TiO₂ coatings for future randomized clinical trials. Full article

The performance of coatings, corrosion barriers, photocatalysts, and tribological materials is greatly influenced by in situ surface properties, requiring highly sensitive and reproducible operando surface characterization methods. We previously developed a temperature-programmed photoelectron emission (TPPE) method to clarify electron transfer behavior on light-irradiated metal surfaces. TPPE is sensitive to surface temperature and prior chemical exposure, which affect the total photoemitted electron count (N_T), the photothreshold, and the activation energy derived from Arrhenius plots of N_T obtained during heating–cooling cycles. This study examines the reproducibility of TPPE data and the TPPE mechanisms for Cu₂O/Cu surfaces subjected to mechanical abrasion, cleaning, plasma treatment, and subsequent immersion in organic liquids. The resulting Arrhenius plots reveal both positive and negative activation energies, depending on the treatment conditions. Negative activation energies during cooling are associated with photoredox-mediated emission. TPPE is attributed to oxygen vacancies within the Cu₂O surface layer, which is interfaced with metallic Cu, serving as a direct probe of these vacancy-related states. The TPPE characteristics (N_T intensity and activation energy) following exposure to various polar and nonpolar organic molecules (e.g., acetone, toluene, hexane, and ethanol) correlate with the electronic properties of these vacancies, consistent with previous observations for ambient air, alcohol, and water vapor exposure. Under illumination, Cu₂O vacancy states enhance photocarrier extraction (electrons and holes) and accelerate surface redox reactions within adsorbed thin films, thereby improving photocatalytic performance. Notably, the solvent’s reciprocal dielectric constant significantly influences TPPE, indicative of electrostatic surface–solvent interactions. Finally, the TPPE mechanism is discussed in the context of antiviral inactivation at the metallic copper–environment interface. Full article

This study evaluated the effects of reduced inclusion levels of coated inorganic compound trace elements as a reduced substitution for uncoated inorganic trace elements in layer breeder diets. A total of 360 Hy-Line Brown layer breeder hens were randomly assigned to three groups, with six replicate pens of 20 hens per group: control group A (inorganic trace elements), group B (500 mg/kg coated inorganic compound trace elements), and group C (1000 mg/kg coated inorganic compound trace elements). Compared with the control, the coated trace element groups significantly increased the laying rate, eggshell strength and yolk color, and decreased the cracked egg rate and feed-to-egg ratio (p < 0.05). Group B had a lower cracked egg rate and a higher egg shape index than group C. Regarding eggshell ultrastructure, group B had a greater effective layer thickness and proportion and a lower mammillary layer thickness and proportion (p < 0.05), while group C presented increased mammillary width. The coated trace elements increased the deposition of Mn, Zn, and Se in eggs and increased serum GSH-Px and Cu-Zn SOD activities and the T3 concentration. No significant differences in hatching performance were observed among the groups. For progeny, groups B and C had higher birth weight, pectoralis muscle weight, and liver weight, as well as improved serum antioxidant indices and intestinal morphology (p < 0.05). The mRNA expression of intestinal tight junction genes was upregulated in group C (p < 0.05) and showed a modest increase in group B. In conclusion, the coated inorganic compound trace elements, when used at reduced inclusion rates, replaced the conventional uncoated inorganic premix without compromising production performance and improved several performance outcomes. The 500 mg/kg inclusion level provided the most balanced improvements in breeder performance and progeny quality while reducing feed costs. These findings suggest that coated mineral technology may sustain productivity at a substantially lower mineral input and may benefit progeny by increasing egg mineral deposition and supporting intestinal development, thereby providing a more sustainable mineral-feeding strategy for breeder hens. Full article

Titanium alloys are widely used for implants, yet corrosion, bacterial colonization and incomplete osseointegration remain important causes of interfacial failure. This review critically analyzes major biomedical functional coating fabrication techniques employed to enhance the surface properties of titanium alloys, including micro-arc oxidation, anodic oxidation, magnetron sputtering, electrochemical deposition, electrophoretic deposition, plasma spraying, physical vapor deposition, plasma immersion ion implantation, laser surface treatment, and hybrid (composite) approaches. For each method, key operational principles, structural and functional characteristics, performance advantages and limitations, and representative application domains are critically analyzed. Across these routes, biological performance depends on coating continuity, pore or nanotube geometry, interfacial bonding, phase composition and ion release. Calcium- and phosphorus-rich oxides and hydroxyapatite deposits generally promote cell adhesion, proliferation, alkaline phosphatase activity, mineralization and osteogenic differentiation. Dense oxide, nitride, tantalum and carbon-based films strengthen corrosion barriers, whereas Mn, Zn, Cu and Ag containing surfaces can inhibit bacterial adhesion and biofilm formation. Excessive ion release, however, may compromise cytocompatibility. Reported outcomes also vary with test medium, exposure time, bacterial strain and cell model. Standardized quantitative endpoints and longer-term corrosion, biofilm and osseointegration studies are required to guide clinically reliable multifunctional coatings. Full article

Crystalline oxide microfeatures offer optical, electronic, catalytic, and interfacial functions, but their fabrication often requires templates, patterned scaffolds, or serial machining. A template-free route converted an electrodeposited Cu₂O coating on Au(111)/Si into substrate-supported vertical microfeatures by anodization at a nominal cell voltage of 10 V in 0.002 mol L⁻¹ Na₂S₂O₈ at 277 K. FE-SEM showed progressive widening of the pre-existing intercolumnar network and narrowing of the retained features. This spatially non-uniform removal identifies preferential dissolution along the intercolumnar network as the principal removal pathway at the coating-morphology scale. From 1 to 8 min, the within-image mean and median feature widths decreased by 36.0% and 45.9%, respectively. The dominant out-of-plane Cu₂O(111) diffraction signature was retained while mean visible reflectance decreased. The Cu-H₂O potential-pH framework provides a qualitative thermodynamic guide to possible oxidative pathways that are evaluated against the experimental evidence. C 1s-referenced XPS provides direct ex situ evidence of an anodization-associated Cu(II)/CuO-like contribution at the outermost surface. Chopped photoelectrochemical measurements showed the largest condition-level light–dark current density contrast after short anodization, providing a secondary functional comparison of the completed coatings. Full article

The persistence of antibiotics like ciprofloxacin (CIP) in aquatic environments necessitates the development of efficient, low-cost wastewater treatment technologies. This study investigates a low-temperature fabrication strategy for mixed-phase copper oxide (CuO/Cu₂O) coatings synthesized via co-precipitation and immobilized using electrophoretic deposition (EPD). A critical finding was that a 25 min precursor aging time (T25) preserved a metastable mixture of CuO and Cu₂O phases, which is highly advantageous for creating heterojunction interfaces that enhance charge separation. In contrast, extended aging (T35) promoted phase consolidation toward bulk CuO, reducing catalytic surface area. During the EPD process, applied voltage acted as an influence to the relative phase composition and deposition behavior of the deposited coatings; 1.0 V was identified as the optimal condition, balancing high phase fidelity with enhanced crystallinity (average crystallite size of 30.6 nm) and mechanical stability. Photocatalytic experiments demonstrated significant CIP degradation, with the 0.9 V and 1.0 V films outperforming the 1.2 V film, possibly due to more favorable surface chemistry and phase diversity. While the 0.9 V film achieved the highest mineralization efficiency (18% TOC removal), the 1.0 V film offered the best balance between photocatalytic activity, structural stability, and phase selectivity for practical applications. High-Performance Liquid Chromatography-Mass Spectrometry HPLC-MS analysis suggested that degradation proceeds through oxidative pathways involving piperazine ring cleavage and defluorination. Full article