Materials最新文献

This paper presents the results of corrosion resistance tests of materials (Fe40Al5Cr0.2ZrB alloy and X18CrN28 steel) in a 5% NaCl solution at room temperature using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization, complemented by confocal/AFM topography and SEM/EDS analysis. Confocal/AFM mapping showed pronounced roughening and localized features on Fe40Al5Cr0.2ZrB alloy (e.g., S_a rising locally to ~1.63 μm), consistent with heterogeneous chloride-induced attack, whereas X18CrN28 steel exhibited only minor roughness changes (S_a ~ 13-19 nm). SEM/EDS of Fe40Al5Cr0.2ZrB alloy revealed mixed oxides with detectable chlorine at corroded sites, while the steel retained a thin, Cr-rich passive layer with negligible Cl signal. Overall, X18CrN28 steel demonstrates significantly higher resistance to localized corrosion in neutral chloride media than Fe40Al5Cr0.2ZrB alloy, aligning electrochemical metrics with surface and chemical analyses.

In an interlayered carbon fiber reinforced polycarbonate (CFRPC) composite constructed of nine CF plies alternating between ten PC sheets, designated [PC]₁₀[CF]₉, applying homogeneous low voltage electron beam irradiation (HLEBI) at 200 kV cathode potential, with V_c setting at a 43.2 kGy dose, to both finished sample surfaces resulted in a 47% increase in Charpy impact strength and a_uc at median fracture probability (P_f) of 0.50 over that of untreated, from 118 kJm^-2 to 173 kJm^-2. Increasingly higher V_c settings of 150, 175, and 200 kV successively increased a_uc at median-P_f of 0.50 to 128, 155, and 173 kJm^-2, respectively. Strengthening is attributed to increasing the HLEBI penetration depth, D_th, into the sample thickness. Since the [PC]₁₀[CF]₉ has an inhomogeneous structure, D_th is calculated for each ply successively into the thickness. Scanning electron microscopy (SEM) photos showed a hierarchy of fracture mechanisms from poor PC/CF adhesion in untreated; to sporadic PC adhesion with aggregated CF at 150 kV; to high consolidation of CFs by PC at 200 kV. X-ray photoelectron spectroscopy (XPS) examination of the CF surface in the fracture area showed C1s carbonate O-(C=O)-O and ester O-(C=O)-R peak generation at 289 to 292 eV to be non-existent in untreated; well-defined at 150 kV; and increased in intensity at 200 kV, after which a reduction was observed at 225 kV. Moreover, the 200 kV yielded the largest area sp³ peak at 49.5%, signifying an increase in graphitic edge planes in the CF, apparently as dangling bonds, for increased adhesion sites to PC. For O1s scan, 200 kV yielded the largest area O-(C=O)-O peak at 34%, indicating maximum PC adhesion to CF. At the higher 225 kV, increase in a_uc at P_f of 0.50 was less, to 149 kJm^-2, and XPS indicated a lower amount of O-(C=O)-O groups, apparently by excess bond severing by the higher V_c setting.

The global challenge of antimicrobial resistance, as well as the need to develop safe and environmentally sustainable materials, has served to stimulate research interest in antimicrobial technologies. The abundance, degradability and environmental friendliness of biopolymers means that they are widely used in medicine, pharmacy, and cosmetology. The focus of this mini review is the development of biopolymer matrices with antimicrobial properties imparted via the inclusion of metal nanoparticles and plant extracts. The review also examines innovative technologies, including photocatalytic systems and intelligent coatings with mechanisms for the controlled release of active substances that can be used to combat microbial infections. We believe that such materials have significant potential for eventual translation to products in the real world.

The CoolMOS^TM (Infineon Technologies AG, Munich, Germany) has been regarded as a device that alleviates high-voltage limitations of unipolar power devices. However, although the theoretical considerations seem to confirm this possibility, this expectation has not been fulfilled to date. It appears that there are some limitations in the CoolMOS^TM concept, and the paper deals with their identification. Part I concentrated on the theory of high-voltage superjunction and its implementation into a power VDMOS transistor, which resulted in the CoolMOS^TM structure. This part is aimed at the physical and technological limitations that have been identified, taking advantage of numerical investigations of CoolMOS^TM structures developed on the basis of a typical VDMOS one.

Restrictive regulations on the use of peat and increasing consumption in modern horticulture production have created an irreconcilable contradiction. Wood fibers (WF) produced from forestry residues are considered as a promising peat substitution. However, their poor water- and nutrient-holding capacity limit their application. Here, wood fiber-hydrogel composite (WF-Gel) was developed via a one-pot strategy by grafting poly(acrylic acid-co-acrylamide) (P(AA-co-AM)) onto WF. The structure of the hydrogel network incorporated with WF was confirmed by FTIR spectrophotometry, scanning electron microscopy, X-ray diffractometry, and thermogravimetric analysis. The growing substrate amended with WF-Gel showed higher physical properties, including water-filled porosity (~62.33%) and water-holding capacity (~44.93%) compared with peat incorporated with WF. The pot experiment revealed that WF-Gel significantly increases the chlorophyll content and relative growth rate of choy sum (Brassica rapa var. parachinensis), especially at the initial transplanting stage. Moreover, choy sum grown in a substrate containing WF-Gel showed a significant increase in biomass accumulation. Additionally, nutrient content and irrigation water-use efficiency data indicated that WF-Gel as a growing medium strongly promotes the water and nutrient efficiency of choy sum. Therefore, the incorporation of this hydrogel modification strategy is a promising approach to promote the water- and nutrient-use efficiency of WF as a soilless substrate component.

Realizing the full potential of optical actuation for high-speed phase-change radio-frequency (RF) switches requires a shift to single-pulse operation. This work presents a systematic investigation of reversible phase transitions in GeTe thin films induced by single 10 ns laser pulses, utilizing spatially resolved characterization techniques, including atomic force microscopy (AFM) and micro-spectroscopy. Precise laser fluence windows for crystallization (12.7-16 mJ/cm²) and amorphization (25.44-41.28 mJ/cm²) are established. A critical finding is that the amorphization process is governed by rapid thermal accumulation, which creates a direct trade-off between achieving the phase transition and avoiding detrimental surface morphology. Specifically, we observe that excessive energy leads to the formation of laser-induced ridges and ablation craters, which are identified as primary causes of device performance degradation. This study elucidates the underlying mechanism of single-pulse-induced phase transitions and provides a practical processing window and design guidelines for developing high-performance, optically actuated GeTe-based RF switches.

The preparation of construction waste into eco-friendly recycled powder (RP), partially replacing cement to produce foam concrete with thermal insulation properties, provides a new approach for the resource utilization of RP. In this study, different components of construction waste were used to prepare recycled paste powder (RPP), recycled brick powder (RBP), and recycled concrete powder (RCP). The effects of RP on the microstructural and macroscopic properties of foam concrete were investigated at replacement rates ranging from 0% to 30%. The research results indicate that the microstructure of all three types of RP exhibits irregular shapes, and their chemical compositions show significant differences. Partial replacement of cement with these RP leads to the deterioration of the matrix microstructure, which negatively affects the workability and mechanical properties of the foam concrete. However, the addition of RP effectively mitigates the drying shrinkage of the foam concrete, with RBP showing particularly outstanding performance in this regard. Specifically, the maximum drying shrinkage rate of F-30RBP is 9.33% and 11.31% lower than that of F-30RPP and F-30RCP, respectively. Furthermore, the incorporation of RP has a minimal effect on the thermal conductivity of the foam concrete, indicating that RP is well-suited for use in foam concrete.

Textile dye effluents, particularly cationic dyes, pose a major environmental challenge, demanding efficient and sustainable adsorbent materials to remove harmful synthetic dyes. In this study, a reference thiourea-formaldehyde (TU/FA) composite and a series of thiourea-poly(acrylic acid)-formaldehyde (TU/PAA/FA) composites were synthesized and systematically characterized. The composites were prepared by varying the volume of poly(acrylic acid) PAA (from 1 to 7.5 mL) to assess how PAA incorporation influences morphology, crystallinity, surface chemistry, charge, and thermal stability. Analytical techniques including SEM, XRD, FT-IR, particle size distribution, zeta potential, and TGA/DTG revealed that increasing PAA content induced more porous and amorphous microstructures, intensified carbonyl absorption, reduced particle size (optimal at 2.5-5 mL PAA), and shifted the zeta potential from near-neutral to highly negative values (-37 to -41 mV). From TU/PAA/FA composite analysis, it was depicted that the TU/PAA-5/FA material has the better characteristics as a potential cationic dye absorbent. Thus, the adsorption performance of this composite toward crystal violet dye was subsequently investigated and compared to the reference material thiourea-formaldehyde (TU/FA). The TU/PAA-5/FA material exhibited the highest capacity (145 mg/g), nearly twice that of TU/FA (74 mg/g), due to the higher density of carboxylic groups facilitating electrostatic attraction. Adsorption was pH-dependent, maximized at pH 6, and decreased with temperature, confirming an exothermic process. Kinetic data followed a pseudo-second-order model (R² = 0.99), implying chemisorption as the rate-limiting step, while Langmuir isotherms (R² > 0.97) indicated monolayer adsorption. Thermodynamic analysis (ΔH° < 0, ΔS° < 0, ΔG° > 0) further supported an exothermic, non-spontaneous mechanism. Overall, the TU/PAA-5/FA composite combines enhanced structural stability with high adsorption efficiency, highlighting its potential as a promising, low-cost material for the removal of cationic dyes from textile effluents.

This article presents the results of research on UV-curable epoxy coatings developed with selected plant modifiers such as garlic (Allium sativum), turmeric (Curcuma longa), common nettle (Urtica dioica), and privet (Ligustrum vulgare). This study aimed to evaluate the influence of these natural components on the functional properties of UV-cured coatings and to assess their potential as bio-based modifiers. The coatings were formulated using Epidian^® 5 epoxy resin, a safe and non-toxic material approved for food-contact applications, and cured with a commercial cationic photoinitiator. Their mechanical, surface, optical, and antibacterial properties were investigated. The results showed that all plant-based additives modified both the mechanical and esthetic characteristics of the coatings; however, garlic demonstrated outstanding antibacterial activity, achieving nearly complete inhibition of Staphylococcus aureus growth with a reduction rate of 99.998%. These findings highlight that natural modifiers, especially garlic, can serve as highly effective functional components, while future work should focus on implementing these coatings for surfaces exposed to bacteria, such as public utility items and shop, hospital, sports, and rehabilitation equipment.

Zinc oxide nanowires are often used to improve the bulletproof performance of high-performance fabrics, but determining the coefficients of inter-yarn friction (CIFs) of those fabrics in numerical ballistic models is a challenge. In this article, the linear method is adopted to obtain the CIF of sateen fabrics with two thread densities treated with zinc oxide nanowires. For treated sateen fabrics with a thread density of 8 ends/cm (S-8-ZnO), the coefficient of static friction (CSF) and coefficient of kinetic friction (CKF) obtained by the linear method are 1.85 and 1.83, respectively. For treated sateen fabrics with a thread density of 13 ends/cm (S-13-ZnO), the CSF and CKF obtained by the linear method are 0.76 and 0.74, respectively. The obtained coefficients are input into the yarn pull-out models of the above two types of sateen fabrics. It is found that for both S-8-ZnO and S-13-ZnO fabrics, the errors of the yarn pull-out force by the linear method are 0.43% and 6.56%, respectively. The method presented in this study provides a more feasible approach for determining the CIF of chemically treated fabrics in future FE simulations.