Journal of Materials Science最新文献

5356 aluminum alloy welding wire is widely used in automotive, aerospace, and marine, due to its excellent corrosion resistance, high strength-to-weight ratio, and excellent weldability. The properties of aluminum alloys are primarily determined by their microstructure. This study investigates the microstructure evolution, mechanical properties, and texture of 5356 aluminum alloy welding wire produced using the continuous casting direct rolling (CCDR) method. The results show that continuous rolling led to an increased generation of dislocations in the matrix, and dynamic recovery plays an important role in reducing dislocation density. As a result of dynamic recovery, the microstructures of 3RPs consist of extensive deformed grains and numerous substructures. The continuous casting direct rolling textures are characterized to be cube and shear textures. After 10 rolling processes, the 5356 aluminum alloy welding wire shows a highest tensile strength of 365 MPa with a lowest elongation of 8.8%. This research provides theoretical guidance to produce high-performance 5356 aluminum alloy welding wires, paving the way for their more efficient and reliable applications.

This study aims to understand the effects of adding octa-phenyl-substituted silsesquioxane (phSQ) on the crystallization process and thermal stability of polylactide (PLA). Nowadays, PLA is the most industrially used compostable polymer, but its uses are limited by its low crystallization and thermal degradation during processing. The possibility of introducing functionalized silsesquioxanes (SQs) to improve thermal stability and increase its crystallinity and ductility in a controlled way is desirable. The nanometric size of the Si-O-Si cage, coupled with the influence of the functional groups attached to its structure, enables it to function as a heterogeneous nucleating agent. In this work, a specially synthesized octa-phenyl-substituted SQ (phSQ) was added to the PLA in 0.5–5 wt%. Crystallization in non-isothermal and isothermal conditions was conducted and monitored using differential scanning calorimetry (DSC); the course of the spherulite formation under identical conditions to DSC was also assessed using optical microscopy in polarized light. The results showed that phSQ increases the degree of crystallinity of PLA by introducing additional sites of heterogeneous nucleation but does not increase the spherulite growth coefficient. Additionally, the analysis of thermal properties indicates that the presence of phSQ could not have a positive impact on thermal stability. The agglomeration of the nanometric particles and changes in the main structural features of the polymeric matrix could be present in the samples, affecting the obtained results.

Graphical abstract

The entanglement of polymers can cause a sharp increase in the viscosity of polymer melt, which is adverse to polymer processing. Disentanglement is an effective method to improve the processing performance of polymers without sacrificing mechanical properties. Although there are some methods to reduce the entanglement degree of polymers, few methods can preserve the disentangled state in pellets for secondary processing. Long-chain branched polypropylene (LCB-PP) has a slower entanglement recovery rate due to its branched chain. Thus, it is worth studying whether the disentangled state of LCB-PP can be kept in pellets to improve processing performance during secondary processing. In this work, disentangled LCB-PP was successfully prepared using the self-designed polymer melt disentanglement device that can apply a complex shear field (a superposition of rotational shear and oscillatory shear) to polymers. The effect of the rotational shear, oscillatory shear, and complex shear on disentanglement was studied. The results show that the complex shear field has a better effect on the disentanglement of LCB-PP, which is endowed with lower viscosity and higher melt flow rate compared to rotational shear and oscillatory shear. In secondary processing, the processing temperature and injection pressure required for disentangled LCB-PP are significantly reduced while mechanical properties are maintained.

Graphical abstract

Silica aerogel membranes are renowned for their high porosity and superior thermal insulation capabilities. However, they are known to have limited mechanical strength and tend to shed surface particles easily. To address these drawbacks, a novel PVDF/SiO₂/PVDF(PSP) composite membrane with a three-layered structure has been successfully fabricated by coating the surface of silica aerogel membranes with polyvinylidene fluoride (PVDF) using a straightforward and effective coating technique. This innovative approach not only effectively addresses the issue of particle shedding but also endows the silica aerogel membrane with organic functionality. The resulting PSP membranes offer significant improvements over traditional polyolefin separators, including higher porosity, enhanced electrolyte affinity, and superior thermal dimensional stability. These membranes boast an impressive ionic conductivity of 1.405 mS/cm and a lithium-ion transference number of 0.550. Moreover, when incorporated into a LiFePO₄-based coin battery, the PSP membranes deliver a remarkable discharge-specific capacity of 143.5 mAh/g and an impressive capacity retention rate of 93.7% after undergoing 200 charge/discharge cycles at a rate of 0.5C.

Graphical abstract

Integrating energy storage and harvesting devices have been major challenges and significant needs of the time for upcoming energy applications. Photosupercapacitors are combined solar cell-supercapacitor devices which can provide next-generation portable powerpacks. Owing to advantages like economic and environmental friendliness, dye-sensitized solar cells (DSSCs) offer vast potential for being integrated with energy accumulation devices like supercapacitors. Over the past few years, various types of harvesting cum storage power devices combining DSSCs and supercapacitors have been reported. Over time the devices have improved in both performance and stability providing a broad outlook to possible future advancements including commercialization. We still have many challenges that are yet to be resolved in order to take these powerpacks to the next level of applications in portable and wearable electronics and communication devices. In this context, a detailed analysis and comparison of already reported photo-powered integrated supercapacitors based on DSSCs would give further insights into future advancements. In this review, we have discussed the development of photosupercapacitors, their fabrication strategies, and different materials used as counter electrodes, electrolytes, and dye sensitizers.

Graphical Abstract

C/C materials represent as materials with specific performance, therefore they are applied in various industries. It is essential to figure out the paths to predict, to provide and to enhance their properties to obtain high performance products. It is well known that strong matrix/reinforcer adhesion provides better strength utilization and therefore better properties for the majority of composite materials of all types (Heim in Compos Part B Eng 54:365–370, 2013), (Hancock and Cuthbertson in J Mater Sci 5:762–768, 1970), (Yang et al. in Polymers 13:2764, 2021). However some researchers note that strong adhesion in the materials that are exposed to high temperatures leads to cracking and significant properties degradation (Vignoles et al. in The Control of interphases in carbon and ceramic matrix composites, Wiley, Hoboken, 2012), (Zhang et al. in Compos Struct 340, 2024). In this work, the effect of the pyrocarbon layer applied on the surface of carbon fibers used for reinforcement of formaldehyde novolac resin based carbon/carbon (C/C) material prepregs was investigated. For the first time we used this effect to prove that lower matrix/reinforcer adhesion in C/C materials prepregs leads to better material behavior during pyrolysis, which results in higher mechanical properties of the pyrolised samples in comparison with the samples demonstrating stronger matrix/reinforcer adhesion. The prepregs were thermally treated at various temperatures, the physical and mechanical performance evolution of the prepregs at different carbonization stages were analyzed. Comparative study of the features of the prepregs with pyrocarbon coated and uncoated carbon fiber as a reinforcement were carried out. The damping effect of the pyrocarbon on the fiber surface were advertised, allowing to mitigate the carbonization-caused effects. The prepregs reinforced with pyrocarbon-modified carbon fibers demonstrated lower cracking performance and higher mechanical performance comparing with the uncoated fiber reinforced prepregs.

Hard carbon materials are attracted as excellent anode materials for sodium-ion batteries due to their good electrical conductivity, high reversible capacity, low operating voltage and stable cycling performance. Herein, waste denim fabrics were used as raw material to prepare denim-based hard carbon (DHC) via a one-step carbonization method, and its sodium storage performance as an anode material for sodium-ion batteries was investigated. The effects of carbonization temperature on the microstructure and electrochemical sodium storage performance of DHC were investigated using X-ray diffraction, N₂ adsorption–desorption isotherms, Raman spectroscopy, scanning electron microscopy, cyclic voltammetry and galvanostatic charge–discharge methods. The results demonstrate that DHC derived at a carbonization temperature of 1300 °C with an optimal graphitic microcrystal size, pore structure and surface defect, exhibits the best electrochemical performance. At a current density of 50 mAh·g⁻¹, it has a reversible specific capacity of 317.1 mAh·g⁻¹ and an initial Coulombic efficiency of 87.76%. After 1000 cycles at a current density of 1000 mA·g⁻¹, the capacity retention rate is 84.5%. This study demonstrates the potential of converting waste textile resources into high-performance materials for sodium-ion batteries, which could contribute to sustainable development by promoting the high-value utilization of textile waste and supporting environmental protection.

Highly stretchable and sensitive strain sensors are immensely desired for motion detection in human-like robots. Here, we report an extremely facile fabrication of carbon nanotubes (CNTs) based ultrasensitive strain sensors. CNTs are coated on a flexible and stretchable commercial fabric using the spray-coating method. Scanning electron microscopy and energy-dispersive X-ray spectroscopy confirm that the CNTs are effectively embedded into fabric fiber frameworks where these act as conducting channels among the individual fibers. A strain sensor is fabricated using the CNTs coated fabric by simply stitching the copper wires along its two opposite edges. The strain is employed systematically and response of the sensor is recorded. The sensor shows an ultrasensitivity of 113,129% for an applied strain of 50% with a notable response and recovery time of 78 ms. The sensor also shows remarkable cycling stability for 5,000 stretching cycles. Moreover, the sensor is evaluated for rotational motion detection in robotics. The sensor with electrode length up to 10 cm can tolerate the rotational motion up to ~ 12,600° (~ 35 rotations), and delivers a stable response. The results show that the demonstrated sensor can act as e-skin for human-like robots where it can effectively monitor the robot motion particularly which involves large random and rotational movements.

Graphical abstract

Polylactic acid (PLA) is a biodegradable thermoplastic that has emerged as a suitable replacement of petroleum-derived polymers commonly used in packaging. In this study, it has been demonstrated that glyceryl tributyrate (TB) and triethyl citrate (TEC), non-toxic, environmentally friendly additives, can be effectively employed as natural, renewable, and sustainable plasticizers to improve PLA’s thermal and physical properties, thus expanding its potential applications. The study initially investigates the impact of varying contents of these two natural plasticizers on PLA properties, identifying the optimal plasticizer percentage based on improvements in PLA performance. PLA/Starch composites were then formulated using the selected percentage of TB or TEC as plasticizers. The study further analyzes the relationship between sample morphology and their thermal and mechanical properties, as well as functional properties relevant to food packaging, such as transparency, water vapor permeation, and migration. PLA-TEC/Starch films exhibited the highest crystallinity and best barrier properties, which was attributed to the different affinities between starch and the plasticizers. Furthermore, the samples were transparent in the visible region of the spectrum but exhibited negligible transmittance in the UV-C region as well as a decrease of migration in isooctane. Therefore, these biodegradable and eco-friendly films show great potential as viable alternatives to traditional packaging materials, particularly for fatty and UV-sensitive foods.

Graphical abstract

The use of microwave absorption (MA) materials in practical aerospace applications would be challenging without a dependable mechanical support structure. However, achieving a wide effective absorption bandwidth (EAB) in aramid honeycomb structures at low weight gain is crucial for the practical aerospace applications of MA materials. To address this challenge, this study proposes a combination of porous carbon foam and high structural strength honeycomb to achieve broadband microwave absorption in structural devices through the synergistic effect of carbon foam absorption and honeycomb structure. The uniform filling process of ultra-lightweight reduced GO aerogel is achieved through freeze-drying, solving the issues of uneven dispersion and incomplete filling of traditional absorbers in honeycombs. Further optimization and comprehensive evaluation of filling concentration and reduction process were carried out. The freeze-drying process combined with chemically reduced honeycomb samples filled with different concentrations of GO all exhibit broadband absorption performance. At a specific standard honeycomb thickness of 15 mm, uniformly filled honeycomb samples with 0.1 to 0.3% GO exhibit triple resonance peaks near 2–3 GHz, 8–9 GHz, and 15 GHz, with effective absorption peaks all below − 10 dB. Moreover, the incorporation of transparent wave honeycomb walls in conjunction with honeycomb materials enhances the overall impedance matching, leading to a further improvement in the EAB to 10.53 GHz for the honeycomb sample filled with 0.2% freeze-dried and reduced GO. CST simulation data confirms that the loss in the honeycomb samples originates from uniform conduction loss, and the electric field stably enters the interior of the honeycomb. This approach, based on the rapid and efficient filling of uniform RGO by freeze-drying, provides a new way to achieve broadband microwave absorption in aramid honeycombs and has significant potential for development in the field of aerospace stealth.