Search Results (187)

With the continuous development of new aircraft, the application of low-cost composite materials technology still encounters numerous challenges and issues. The development of low-cost composite technology, while ensuring the high reliability of aircraft components, has become a common concern among aerospace composites. The research presented in this paper examines the findings related to the conformity verification process of an electric aircraft in China. This is an all-composite structural general aviation aircraft certified under CCAR Part 23. This study focuses on the quality characteristics of low-cost wet vacuum bagging composites, addressing the causes and effects of high porosity in the manufacturing process. Based on the research findings, a relationship between porosity and the strength of wet vacuum bagging composites is established. Consequently, a safe and reliable method for ensuring airworthiness conformity of low-cost composites is proposed and implemented in the aircraft type’s conformity verification. Furthermore, this paper discusses the development trends of low-cost composites for general aviation, providing valuable insights for the advancement of low-cost technologies in the future. Full article

Background/Objectives: Additive manufacturing (AM) enables the production of cementless acetabular cups with porous surfaces that facilitate early osseointegration. Directed energy deposition (DED), a form of AM, allows the direct welding of porous structures onto metal substrates without requiring a vacuum environment, offering advantages over conventional powder bed fusion methods. Despite growing interest in DED, no prospective clinical studies evaluating DED-based acetabular components have been published to date. This study assessed short-term outcomes of a DED-based 3D-printed acetabular cup in total hip arthroplasty (THA). Methods: A total of 120 patients who underwent primary cementless THA using the Corentec Mirabo Z^® acetabular cup were prospectively enrolled. Among them, 124 hips from 100 patients who had completed a minimum of 24 months of follow-up were included in the analysis. Clinical outcomes were assessed using the Harris hip score (HHS), WOMAC, EQ-5D-5L, and pain NRS. Radiographic evaluation included measurements of cup position, osseointegration, and detection of interfacial or polar gaps on CT and plain radiographs. Implant-related complications were also recorded. Results: At a mean follow-up of 34.6 months, the implant survival rate was 99.3%, with one revision due to suspected osseointegration failure. The HHS improved from 56.6 to 91.4 at 24 months, and the NRS decreased from 6.2 to 1.1 (both p < 0.001). Interfacial gaps were observed in 58.1% of cases on CT, though most were <1 mm and not clinically significant. Common postoperative issues included greater trochanteric pain syndrome, squeaking, and iliotibial band tightness, all of which were resolved with conservative treatment. Conclusions: DED-based 3D-printed acetabular cups demonstrated favorable short-term clinical and radiographic outcomes, with high survivorship and reliable early osseointegration in cementless THA. Full article

Beryllium-based intermetallic compounds, such as Be₁₂Nb, are attracting growing interest for their high thermal stability and potential to replace pure beryllium as neutron reflectors and multipliers in both fission and future fusion reactors, with additional applications in metallurgy, aerospace, and hydrogen technology. The paper presents the results of an investigation of the thermal treatment and phase formation of the intermetallic compound Be₁₂Nb from a mixture of niobium and beryllium powders in the temperature range of 800–1300 °C. The phase evolution was assessed as a function of sintering temperature and time. A nearly single-phase Be₁₂Nb composition was achieved at 1100 °C, while decomposition into lower-order beryllides such as Be₁₇Nb₂ occurred at temperatures ≥1200 °C, indicating thermal instability of Be₁₂Nb under vacuum. Careful handling of sintering in low vacuum minimized oxidation, though signs of possible BeO formation were noted. The findings complement and extend earlier reports on Be₁₂Nb synthesis via plasma sintering, mechanical alloying, and other powder metallurgy routes, providing broader insight into phase formation and synthesis. These results provide a foundation for optimizing the manufacturing parameters required to produce homogeneous Be₁₂Nb-based components and billets at an industrial scale. Additionally, they help define the operational temperature limits necessary to preserve the material’s phase integrity during application. Full article

In this work, the mechanical properties of jute fiber-reinforced polymers were investigated, considering two manufacturing technologies—wet layups and vacuum-assisted resin infusion—with the aim of developing cost-effective composite materials based on natural fibers. In the manufacturing process, two different types of resins were used, specific to each technology. Specimens measuring 25 mm × 200 mm were cut from the resulting laminates at three orientations (0°, 45° and 90° with respect with the weft orientation), and they were subjected to tensile tests. The results showed that resin infusion yielded superior stiffness and strength values when compared to the wet layup. Multi-scale modeling techniques were applied in order to estimate the properties of the fibers and evaluate the orthotropic properties of the composites, and virtual material models that included orthotropic elasticity and the anisotropic Hill plasticity formulation were developed and evaluated, managing to reproduce the experimental data using finite element analyses with decent accuracy. Full article

Electrolytic copper foil is one of the core materials in the fields of electronics, communications, and power. The cathode roller is the key component of the complete set of electrolytic copper foil equipment, and the quality of the titanium cylinder of the cathode roller directly determines the quality of the electrolytic copper foil. There typically exists a longitudinal weld on the surface of the cathode roller’s titanium cylinder sleeve manufactured by the welding method, which leads to the degradation of the quality of the electrolytic copper foil. Refining the grains in the weld zone and the heat-affected zone to close to those of the base material is a key solution for the manufacturing of welded cathode rollers. In order to effectively modify the microstructure and obtain an optimal refining effect in the weld zone of a TA1 cathode roller, a novel composite technology consisting of low-energy and fewer-pass welding combined with multi-pass rolling deformation and vacuum annealing treatment was primarily explored for high-purity TA1 titanium plates in this study. The microstructure of each area of the weld was observed using the DMI-3000M optical microscope, and the hardness was measured using the HVS-30 Vickers hardness tester. The research results show that the microstructure of each area of the weld can be effectively refined by using the novel composite technology of low-energy and fewer-pass welding, multi-pass rolling deformation, and vacuum annealing treatment. Among the explored experimental conditions, the optimal grain refinement effect is obtained with a V-shaped welding groove and four passes of welding with a welding current of 90 A and a voltage of 8–9 V, followed by 11 passes of rolling deformation with a total deformation rate of 45% and, finally, vacuum annealing at 650 °C for 1 h. The grain size grades in the weld zone and the heat-affected zone are close to those of the base material, namely grade 7.5~10, grade 7.5~10, and grade 7.5~10 for the weld zone, heat-affected zone, and base material, respectively. Meanwhile, this technology can also refine the grains of the base material, which is conducive to improving the overall mechanical properties of the titanium plate. Full article

Plasma impedance monitoring in semiconductor manufacturing processes is performed using external sensors, such as voltage-current (VI) probes or directional couplers. Plasma chamber impedance measurements, conducted in non-50 Ω matched transmission lines, suffer from a lack of clean signals due to phase variations and the nonlinearity of plasma, thus, sensor calibration is required for each installment. In this study, we monitored plasma impedance in situ based on the position of the vacuum variable capacitor within the matching network, without employing an external VI probe. We observed changes in the matching position according to parameter variations and subsequently confirmed that the calculated plasma impedance also varied accordingly. This study demonstrates the feasibility of real-time plasma impedance monitoring under 50 Ω-matched conditions without the use of external sensors, thereby simplifying plasma diagnostics. Full article

The development of lightweight construction is of crucial importance for the development of sustainable technologies and for the reduction in carbon dioxide emissions, especially in the automotive industry. This study aims to address the challenges associated with manufacturing plant fibre-based polymer composites. The investigation focused on two novel formulations of bio-based unsaturated polyester resins, assessing their viability as a matrix in plant fibre-reinforced composites within the context of automotive applications. The study addresses the challenges related to the preparation and processing of the system, leading to the necessity of diluting the resin with (hydroxymethyl)methacrylate (HEMA) to achieve an applicable viscosity. Two different flax fibre textiles, in the form of a short fibre mat and a woven fabric, were used as reinforcement. The composite panels were manufactured using the vacuum-assisted resin infusion (VARI) process. The most efficacious material combination, comprising Bcomp^® ampliTex™ 5040 and STRUKTOL^® POLYVERTEC^® 3831, with viscosity modified by 39% HEMA, exhibited a consistent fibre volume fraction of 40% and a glass transition temperature of 70 °C. In addition, the mechanical behaviour in the 0°-direction demonstrated tensile strength and modulus values of approximately 99 MPa and 9 GPa, respectively, accompanied by an elongation at break of 2%. The flexural modulus was found to be 7 GPa, and the flexural strength 94 MPa. Full article

This study investigates the mechanical performance of basalt fiber-reinforced polymer (BFRP) laminates as a suitable alternative to conventional glass fiber-reinforced composites for marine applications. The laminates were produced by varying the main process parameters: the fiber type was either glass or basalt; the resin material was either polyester or vinylester; the fiber orientation in selected layers was set to either 0°/90°, or to ±45° by rotating the woven fabrics during lay-up, and finally the manufacturing technique was either hand lay-up or vacuum infusion. Three-point flexural tests with different spans were conducted to evaluate the flexural behavior and fracture mechanisms. The best-performing configuration, based on glass fibers and vacuum infusion, achieved a maximum flexural strength of about 500 MPa, while basalt-based laminates reached values of up to 400 MPa. Basalt laminates exhibited the highest flexural modulus, with values exceeding 24 GPa. An increase in span length from 120 mm to 220 mm resulted in a reduction in flexural strength of approximately 6–18% depending on the laminate configuration, highlighting the influence of loading conditions on mechanical behavior. The effect of the manufacturing processes was also evaluated using an analysis of variance. This showed that fiber type, manufacturing method, and span significantly influenced the mechanical performance. Full article

The discontinuation of commercially available saline and hypertonic saline wound dressings for the veterinary market has restricted options available to veterinary practitioners treating contaminated and infected wounds. Clinicians may manufacture their own homemade solutions in clinics or field settings to treat equine or livestock species; however, information is limited on whether autoclave sterilization is necessary or sufficient to eliminate bacterial growth in isotonic and concentrated salt solutions and how long they may subsequently be stored prior to use. The purpose of this study was to assess sterility of saline (0.9%) and hypertonic saline (20%) solutions manufactured three ways (1—autoclaved glass bottle that was autoclaved again following solution preparation; 2—autoclaved glass bottle, not autoclaved again following preparation; 3—non-autoclaved plastic bottle, not autoclaved following preparation). Solutions were stored two different ways (1—solution in sealed bottle or 2—soaked gauze in vacuum-sealed plastic packets). Products were assessed for bacterial growth at four time points (baseline, one week, one month, six months). At each time point, samples of each solution were plated on Luria–Bertani (LB) agar plates and assessed for bacterial growth at 24 h. Vacuum-sealed soaked gauze was placed in antibiotic-free growth media for 24 h, and then media were plated on LB agar plates and assessed for bacterial growth at 24 h. If bacterial growth was detected, qualitative culture with sensitivity was performed to identify bacterial isolates. No bacterial growth was detected in stored solutions for any preparation method, concentration or time point assessed. Bacterial growth was detected from 0.9% saline-soaked gauze at 1 week, 1 month and 6 months in all container types for at least one time point. Bacterial culture revealed Ralstonia, Bacillus, Sphingomonas and Staphylococcus species. Environmental controls (water, containers, salt, biosafety cabinet and benchtop) were submitted for culture to identify the source of contamination, yielding light mixed growth from tap water and no growth from any other locations. These findings provide clinicians with practical information to guide preparation and storage of homemade saline-based products for wound care. Full article

The Er-Zr-Sc-modified Al-Mg alloys produced by additive manufacturing (AM) exhibit good formability and excellent mechanical properties, and present great potential for applications in the fields of aerospace and automotive fields. In this work, the preparation process of Al-4.5Mg-0.7Er-0.5Zr-0.3Sc high-strength aluminum alloy powder for additive manufacturing by vacuum induction melting gas atomization (VIGA) was investigated. With the goal of obtaining excellent sphericity and higher powder yield in the particle size range of 15~53 μm, a new type atomizer with optimized convergence angle and tube extension length was designed based on finite element numerical simulation and experimental research, and the optimal atomization processing parameters were determined. The results revealed that when the convergence angle was 32° and the extension length was 5 mm, the large negative pressure and suction force at the tube outlet could facilitate the smooth flow of the melt and a refined powder particle size; when the melt temperature was 800 °C and the atomization pressure was 3.25 Mpa, the melt had low viscosity and the atomization gas could fully interact with the melt. Meanwhile, the melt droplets had suitable cooling conditions, avoiding the generation of irregular powders and improving the powder sphericity. Under the above optimal processing parameters, the prepared powders were spherical or nearly spherical with fine particle size and a high yield of about 39.45%. Full article

In industrial manufacturing, product quality is of paramount importance, as surface defects not only compromise product appearance but may also lead to functional failures, resulting in substantial economic losses. Detecting defects on complex surfaces remains a significant challenge due to the variability of defect characteristics, interference from specular reflections, and imaging non-uniformity. Traditional computer vision algorithms often fall short in addressing these challenges, particularly for defects on highly reflective curved surfaces such as aircraft engine blades, bearing surfaces, or vacuum flasks. Although various optical imaging techniques and advanced detection algorithms have been explored, existing approaches still face limitations, including high system complexity, elevated costs, and insufficient capability to detect defects with diverse morphologies. To address these limitations, this study proposes an innovative approach that analyzes the propagation of light on complex surfaces and constructs a polarization imaging system to eliminate glare interference. This imaging technique not only effectively suppresses glare but also enhances image uniformity and reduces noise levels. Moreover, to tackle the challenges posed by the diverse morphology of defects and the limited generalization ability of conventional algorithms, this study introduces a novel multi-scale edge information selection module and a Focal Modulation module based on the YOLOv11 architecture. These enhancements significantly improve the model’s generalization capability across different defect types. Experimental results show that, compared to state-of-the-art object detection models, the proposed model achieves a 3.9% increase in precision over the best-performing baseline, along with notable improvements in recall, mAP50, and other key performance indicators. Full article

We present the design and manufacturing of a deployable conical log spiral spring antenna for small spacecraft, along with a test campaign to evaluate its suitability for space applications. The conical spring was 45.7 cm in height, with base and apex diameters of 18.9 and 2.8 cm, respectively. The spring had a mass of 0.138 kg and was constructed from a carbon fiber-infused epoxy matrix with an embedded coaxial cable. We conducted dynamic and thermal mechanical analysis to determine the coefficient of thermal expansion and glass transition temperature. The initial 10 compressions of the spring shortened the structure’s overall height, but the change had a negligible effect on the antenna’s radio frequency (RF) performance. Thermal cycling between −70 °C and 80 °C did not cause any damage or deformation to the spring structure. Outgassing tests were conducted in a thermal vacuum chamber, and the total mass loss was 0.03%. We conducted vibration tests representative for a typical launch vehicle, and all natural frequencies remained stable above 250 Hz, while the antenna was stowed, satisfying launch vehicle requirements. Post-test functional checks confirmed that there was no change in antenna functionality. The environmental test results provide confidence that the antenna is suitable for spacecraft applications. Full article

Solution-processed oxide thin-film transistors (TFTs) can lead to a significant cost-effective process and suitable for large-scale fabrication. However, they often face limitations, such as lower field-effect mobility, the use of indium which is toxic and rare, and degradation compared to vacuum-based technologies. The single-walled carbon nanotubes (SWNTs) were incorporated with zinc–tin oxide (ZTO) precursor solution without dispersants for the device’s active layer. Sol–gel solution-based ZTO/single-wall carbon nanotube (ZTO/SWNT) (TFTs) with various SWNT concentrations were fabricated to improve the performance of ZTO TFTs. ZTO TFTs containing SWNTs exhibited better electrical performance than those without SWNTs. Among the samples, the ZTO TFT with an SWNT concentration of 0.07 wt.% showed a field-effect mobility (μsat) of 13.12 cm²/Vs (increased by a factor of 3) and an I_on/I_off current ratio of 7.66 × 10⁷ with a lower threshold voltage. SWNTs in the ZTO/SWNTs acted as carrier transfer rods, playing a crucial role in controlling the electrical performance of ZTO TFTs. The proposed fabrication of a sol–gel solution-based process is highly compatible with existing processes because it brings ZTO/SWNT hybrid TFTs closer to practical application, opening up the possibilities for next-generation electronics in flexible devices and low-cost manufacturing. Full article

The boiling point of metals is dependent on the ambient pressure. Therefore, in laser-based fusion welding and additive manufacturing processes, the resulting process regime, ranging from heat conduction welding to the keyhole mode, is also influenced by the process pressure. While laser welding deliberately uses reduced process pressures to achieve the keyhole mode with a lower laser power input as well as a more stable keyhole, there are no positive findings on the laser powder bed fusion process (PBF-LB/M) under vacuum conditions so far. Furthermore, the literature suggests that the process window is significantly reduced, particularly in the high vacuum regime. However, this work demonstrates that components made of the ferritic steel 22NiMoCr3-7 can be successfully manufactured at low process pressures of ${2 \times 10}^{-2} \mathrm{mbar}$ using a double-scanning strategy. The strategy consists of a first scan with a defocused laser beam, where the powder is preheated and partially sintered, followed by a second scan with a slightly defocused laser beam, in which the material within a single layer is completely melted. To test this manufacturing strategy, 16 test cubes were manufactured to determine the achievable relative densities and tensile specimens were produced to assess the mechanical properties. Metallographic analysis of the test cubes revealed that relative densities of up to 98.48 ± 1.43% were achieved in the test series with 16 different process parameters. The tensile strength determined ranged from 722 to 724 MPa. Additionally, a benchmark part with complex geometric features was successfully manufactured in a high vacuum atmosphere without the need for a complex parameterization of individual part zones in the scanning strategy. Full article

Chemical vapor deposition (CVD) is a highly adaptable manufacturing technique used to fabricate high-quality thin films, making it essential across numerous industries. As materials fabrication processes progress, CVD has advanced to enable the precise deposition of both inorganic 2D materials, such as graphene and transition metal dichalcogenides, and high-quality polymeric thin films, offering excellent conformality and precise nanostructure control on a wide range of substrates. Conjugated conducting polymers have emerged as promising materials for next-generation electronic, optoelectronic, and energy storage devices due to their unique combination of electrical conductivity, optical transparency, ionic transport, and mechanical flexibility. Oxidative CVD (oCVD) involves the spontaneous reaction of oxidant and monomer vapors upon their adsorption onto the substrate surface, resulting in step-growth polymerization that commonly produces conducting or semiconducting polymer thin films. oCVD has gained significant attention for its ability to fabricate conjugated conducting polymers under vacuum conditions, allowing precise control over film thickness, doping levels, and nanostructure engineering. The low to moderate deposition temperature in the oCVD method enables the direct integration of conducting and semiconducting polymer thin films onto thermally sensitive substrates, including plants, paper, textiles, membranes, carbon fibers, and graphene. This review explores the fundamentals of the CVD process and vacuum-based manufacturing, while also highlighting recent advancements in the oCVD method for the fabrication of conjugated conducting and semiconducting polymer thin films. Full article