C/C-SiC-(ZrxHf1-x)C composites were formed by means of the reactive melt infiltration method. Investigating the ablation characteristics and structural evolution of C/C-SiC-(ZrxHf1-x)C composites, along with the microstructure of the porous C/C substrate and the composite itself, was the focus of this systematic study. The results demonstrate that the C/C-SiC-(ZrxHf1-x)C composites are predominantly comprised of carbon fiber, carbon matrix, SiC ceramic, (ZrxHf1-x)C, and (ZrxHf1-x)Si2 solid solutions. Improving the pore structure's characteristics fosters the creation of (ZrxHf1-x)C ceramic material. Around 2000 degrees Celsius, in an air-plasma environment, the C/C-SiC-(Zr₁Hf₁-x)C composite material demonstrated outstanding ablation resistance. CMC-1 achieved the lowest mass and linear ablation rates, of 2696 mg/s and -0.814 m/s, respectively, following 60 seconds of ablation, thus demonstrating lower values compared to the ablation rates for CMC-2 and CMC-3. The bi-liquid phase and liquid-solid two-phase structure formed on the ablation surface during the process, obstructing oxygen diffusion and reducing further ablation, which accounts for the superior ablation resistance of the C/C-SiC-(Zr<sub>x</sub>Hf<sub>1-x</sub>)C composite material.
Two foams derived from banana leaf (BL) and stem (BS) biopolyols were created, and their mechanical response under compression, and their intricate three-dimensional microstructures were investigated. Using X-ray microtomography, in situ tests and traditional compression methods were executed concurrently during the 3D image acquisition process. A methodology encompassing image acquisition, processing, and analysis was created to classify foam cells, determine their quantities, volumes, and shapes, incorporating the compression techniques. check details The BS foam exhibited a comparable compression pattern to the BL foam, yet boasted a cell volume five times greater on average. Increasing compression levels demonstrated a concurrent rise in cellular numbers, while the mean cell volume concurrently shrank. Unchanged by compression, the cells displayed an elongated shape. The possibility of cell collapse offered a potential explanation for these attributes. A broader analysis of biopolyol-based foams, facilitated by the developed methodology, seeks to confirm their use as environmentally preferable alternatives to traditional petrol-based foams.
A comb-like polycaprolactone gel electrolyte, fabricated from acrylate-terminated polycaprolactone oligomers and a liquid electrolyte, is presented herein, along with its synthesis and electrochemical performance characteristics for high-voltage lithium metal batteries. This gel electrolyte's ionic conductivity, measured at room temperature, reached 88 x 10-3 S cm-1, a considerably high value capable of ensuring stable cycling in solid-state lithium metal batteries. check details The transference number for lithium ions was measured at 0.45, which helped prevent concentration gradients and polarization, thus inhibiting lithium dendrite growth. The gel electrolyte's oxidation voltage extends to a maximum of 50 volts versus Li+/Li, along with its perfect compatibility with metallic lithium electrodes. Superior cycling stability, a hallmark of LiFePO4-based solid-state lithium metal batteries, stems from their exceptional electrochemical properties. These batteries achieve a substantial initial discharge capacity of 141 mAh g⁻¹ and maintain a capacity retention exceeding 74% of the initial specific capacity after 280 cycles at 0.5C, operating at room temperature. This paper describes a remarkably effective in-situ gel electrolyte preparation technique, yielding an outstanding gel electrolyte ideal for high-performance lithium metal battery applications.
High-quality, flexible, and uniaxially oriented PbZr0.52Ti0.48O3 (PZT) thin films were produced on polyimide (PI) substrates that were previously coated with RbLaNb2O7/BaTiO3 (RLNO/BTO). Employing KrF laser irradiation, a photo-assisted chemical solution deposition (PCSD) process was used to fabricate all layers, enabling the photocrystallization of the printed precursors. Flexible PI sheets, coated with Dion-Jacobson perovskite RLNO thin films, served as seed layers for the uniaxial growth of PZT films. check details To achieve a uniaxially oriented RLNO seed layer, a BTO nanoparticle-dispersion interlayer was fabricated to prevent PI substrate damage from excessive photothermal heating. Growth of RLNO was observed at approximately 40 mJcm-2 at 300°C only. By employing a flexible (010)-oriented RLNO film on BTO/PI, PZT film with high (001)-orientation (F(001) = 0.92) and without any micro-cracks was successfully grown through KrF laser irradiation of a sol-gel-derived precursor film at 50 mJ/cm² at 300°C. The top portion of the RLNO amorphous precursor layer was the sole location for uniaxial-oriented RLNO growth. The oriented and amorphous components of RLNO are critical to the development of this multilayered film, (1) fostering the oriented growth of the overlying PZT film and (2) mitigating stress in the underlying BTO layer, thus minimizing microcrack formation. This marks the inaugural direct crystallization of PZT films on flexible substrates. The fabrication of flexible devices is economically viable and in high demand, due to the combined processes of photocrystallization and chemical solution deposition.
By simulating ultrasonic welding (USW) of PEEK-ED (PEEK)-prepreg (PEI impregnated CF fabric)-ED (PEEK)-PEEK lap joints, an artificial neural network (ANN) model, leveraging expanded experimental and expert data sets, identified the optimal welding parameters. Experimental procedures confirmed the simulation's results, wherein mode 10 (900 milliseconds, 17 atmospheres, 2000 milliseconds) exhibited the high-strength characteristics and preserved the structural integrity of the carbon fiber fabric (CFF). Employing the multi-spot USW method, particularly mode 10, enabled the fabrication of the PEEK-CFF prepreg-PEEK USW lap joint, which demonstrated resistance to a 50 MPa load per cycle, signifying the minimum high-cycle fatigue endurance. ANN simulation of the USW mode, focused on neat PEEK adherends, did not enable bonding for both particulate and laminated composite adherends, specifically those reinforced with CFF prepreg. The process of forming USW lap joints benefited from USW durations (t) being considerably augmented, reaching 1200 and 1600 ms, respectively. The upper adherend serves as a conduit for more efficient elastic energy transfer to the welding zone, in this case.
Conductor alloys of aluminum, enhanced with 0.25 weight percent zirconium, are employed. Our research targeted alloys that were further alloyed with X, such as Er, Si, Hf, and Nb. The alloys' fine-grained microstructure was a result of equal channel angular pressing and rotary swaging procedures. An investigation into the thermal stability of the microstructure, specific electrical resistivity, and microhardness of novel aluminum conductor alloys was undertaken. To determine the nucleation mechanisms of Al3(Zr, X) secondary particles during the annealing of fine-grained aluminum alloys, the Jones-Mehl-Avrami-Kolmogorov equation was employed. The analysis of grain growth data in aluminum alloys, guided by the Zener equation, produced the relationship between annealing time and the average secondary particle sizes. Preferential nucleation of secondary particles at the cores of lattice dislocations was observed during prolonged, low-temperature annealing (300°C, 1000 hours). Prolonged annealing at 300°C results in the Al-0.25%Zr-0.25%Er-0.20%Hf-0.15%Si alloy achieving an optimal synergy between microhardness and electrical conductivity (598% IACS, microhardness = 480 ± 15 MPa).
Devices built from high refractive index dielectric materials, namely all-dielectric micro-nano photonic devices, provide a platform for the low-loss manipulation of electromagnetic waves. The manipulation of electromagnetic waves by all-dielectric metasurfaces presents a previously unimagined prospect, including the focusing of electromagnetic waves and the generation of structured light. Metasurface advancements in dielectric materials are correlated with bound states in the continuum, featuring non-radiative eigenmodes that are located above the light cone, supported by the metasurface's design. Our proposed all-dielectric metasurface, comprised of periodically arranged elliptic pillars, demonstrates that shifting a solitary elliptic pillar precisely controls the extent of the light-matter interaction. Specifically, when an elliptic cross pillar exhibits C4 symmetry, the quality factor of the metasurface at that point is unbounded, referred to as bound states in the continuum. The C4 symmetry's disruption, achieved by moving a single elliptic pillar, results in mode leakage within the corresponding metasurface; nonetheless, the large quality factor is retained, identified as quasi-bound states in the continuum. Simulated results verify that the designed metasurface is responsive to modifications in the refractive index of the ambient medium, thereby confirming its applicability to refractive index sensing. The metasurface, when coupled with the specific frequency and refractive index variations of the surrounding medium, allows for the effective encryption and transmission of information. We expect that the designed all-dielectric elliptic cross metasurface's sensitivity will propel the progress of miniaturized photon sensors and information encoders.
This paper details the fabrication of micron-sized TiB2/AlZnMgCu(Sc,Zr) composites through selective laser melting (SLM) employing directly mixed powders. Dense, crack-free, SLM-fabricated TiB2/AlZnMgCu(Sc,Zr) composite samples, exceeding 995% relative density, were produced and their microstructure and mechanical properties were subsequently examined. Introducing micron-sized TiB2 particles into the powder is shown to enhance laser absorption, subsequently reducing the energy density needed for Selective Laser Melting (SLM) and ultimately improving densification. While some TiB2 crystals adhered coherently to the matrix, a portion of the TiB2 particles broke apart and did not connect; nonetheless, MgZn2 and Al3(Sc,Zr) can facilitate the formation of intermediate phases, connecting these unattached surfaces to the aluminum matrix.