Due to the addition of short/continuous fibers with better mechanical properties, FDM 3D-printed short- and continuous-fiber-reinforced PEEK composites possess better performance than printed PEEK. However, the interlayer bonding performance becomes poor due to the layer stacking and weak fiber–resin interface adhesion. In this study, a heat treatment process was proposed to improve the interlaminar bonding properties of 3D-printed short- and continuous-fiber-reinforced PEEK composites. The effects of heat treatment temperature and time on the interlaminar shear strength, porosity and dimensional change of printed samples were studied by a single-factor experiment. Moreover, the thermal properties and fracture morphology of FDM 3D-printed fiber-reinforced PEEK composites before and after heat treatment were investigated to explore the toughening and strengthening mechanism. The experimental results showed that the mechanical properties of FDM 3D-printed fiber-reinforced PEEK composites improved by heat treatment process can be attributed to the improvement of crystallinity and interfacial bonding. The heat treatment process can also improve the infiltration and diffusion among adjacent filaments and layers, and further reduce the defects. The optimized heat treatment temperature and time were 250 °C and 6 h, respectively. The maximum ILSS of FDM 3D-printed short- and continuous-fiber-reinforced PEEK composites increased by 16 and 85% compared with untreated samples, respectively. Full article

Feather and down textiles are widely used in our daily life, especially in winter. However, they are easily drilled out from the fabric body and are difficult to machine-wash, which thereby blocks their widespread application. In order to solve these issues, a highly anti-drilling, breathable and machine-washable ePTFE-aided down-proof cotton fabric was prepared in this work, which was done by modifying a plain-weave cotton fabric with expanded polytetrafluoroethylene (ePTFE) nanofiber membrane via point glue method. The fabrication procedure is simple, scalable and environmentally friendly, which is a prerequisite for large-scale production. The effects of tumble and washing cycles on pore size distribution and the corresponding anti-drilling behavior of the prepared down-proof fabric were systematically investigated. Furthermore, the machine washability, air permeability, thermal insulation and tensile properties of the fabric were studied. The results demonstrated that less than five drilled files escaped from the fabric surface, irrespective of tumble and/or laundering cycles, and it also has the advantages of being lightweight (<83 g/m²), having high breathability, a good thermal insulation rate (≈80%) and can be washed with surfactant by a laundry machine without explosion. Benefiting from the above characteristics, the as-prepared ePTFE-aided down-proof cotton fabric presents its potential application in the field of home textiles. Full article

In this work, TiC/M2 high speed steel metal matrix composites (MMCs) were prepared using the ball milling method and laser powder bed fusing process. By controlling the TiC content in TiC/M2HSS, the grain size, phase composition, and frictional wear properties of the samples were enhanced. The results showed that when TiC/M2HSS was supplemented with 1% TiC, the surface microhardness of the samples increased to a maximum value and the wear volume decreased by approximately 39%, compared to pure M2HSS. The hardness and friction wear properties of the TiC/M2HSS composites showed a decreasing trend as the TiC content increased, owing to an increase in internal defects in the samples, as a result of excess TiC addition. The physical phases of the TiC/M2HSS MMC samples prepared by LPBF were dominated by the BCC phase, with some residual FCC phases and carbide phases. This work explored the possibility of enhancing the frictional wear performance of TiC/M2HSS samples by controlling the TiC content. Full article

Graphene oxide is obtained by oxidation of graphite followed by ultrasonic exfoliation. It is a two-dimensional layered material with a large number of oxygen-containing functional groups on its surface. Polyaniline is a conductive polymer and has a unique corrosion protection mechanism. In this study, carboxy-functionalized graphene oxide/polyaniline (CGO/PANI) composites with a lamellar structure were prepared by in situ polymerization. The lamellar layer was used to form a labyrinthine structure in the coating to effectively retard the penetration of corrosive media. The electrical conductivity of polyaniline can promote the formation of conductive pathways between zinc particles and improve the utilization of zinc powder. Polyaniline is also able to passivate the substrate, further improving the coating’s ability to protect steel substrates against corrosion. In this paper, the in situ polymerization of aniline on carboxy-functionalized graphene oxide flakes was confirmed by scanning electron microscopy (SEM), Fourier infrared spectroscopy (FT-IR), and X-ray diffraction (XRD), and the improvement of the corrosion resistance of the prepared composites on the epoxy zinc-rich coatings was evaluated by SEM, electrochemical impedance spectroscopy (EIS), and salt spray resistance tests. The results showed that aniline was successfully polymerized in situ on carboxy-functionalized graphene oxide, and the modified coating had significantly improved anticorrosive properties, where the best anticorrosive improvement was achieved when CGO: PANI = 0.03. Full article

The current work deals with the fabrication of novel MoO₃ nanostructured films with Ce and Cu co-doping through the spray pyrolysis route on a glass substrate maintained at 460 °C for the first time. The phase of developed films was approved by an X-ray diffraction study, and the crystallite size was determined between 82 and 92 nm. The optical transmission of the developed films was noticed to be reduced with doping and found between 45 and 90% for all films, and the absorption edge shifted to a higher wavelength with doping. The optical energy gap of the fabricated films was found to be reduced from 3.85 to 3.28 eV with doping. The developed films were used to degrade the harmful Eosin-Y dye under UV light. The system with 2% Ce and 1% Cu-doped MoO₃ turned out to be the most effective catalyst for photodegradation of the dye in a period of 3H and almost degrade it. Hence, the MoO₃ films prepared with 2% Ce and 1% Cu will be highly applicable as photocatalysts for the removal of hazardous dye from wastewater. Full article

Titanium alloy is widely used in the aviation sector and has become the most important structural material in aircraft manufacturing. However, manufacturing a large-scale titanium component owns a high buy-to-fly ratio due to its poor machinability and expensive price. Over the last decade, the additive manufacturing (AM) technology has developed rapidly and has become a promising processing method for titanium alloys. In the future, in order to enhance processing efficiency and material utilization, a higher laser energy source is supposed to be applied in AM processes. Nevertheless, porosity within the AM fabricated part is the most important issue that restricts the application of AM technology. In the present work, two bulks with different porosities were fabricated using high-power direct energy deposition (HP-DED), and the high cycle fatigue (HCF) performance of the as-build part was tested and compared. The result shows that a lack of fusion (LOF), spherical pores and un-melted particles are the main porosity defects in the as-build part. The shape, size and location of the defect will have a synthetic effect on HCF performance. In addition, the unstable key-hole during the process will facilitate the formation of a pore, which consequently increases the porosity. Online monitoring and closed-loop feedback systems should be established for enhancing the process stability. Full article

Mold growth is a continuing issue when it comes to human health, as well as a growing concern in localized wood decay, as numerous ‘traditional’ molds have been found to have soft rotting capabilities. Mold inhibitors on the market are often synthetic; however, the fungal kingdom has a wide range of more ‘natural’ options. Pigments produced by many fungi have been found to be toxic to other fungi, especially soft rotting fungi. This study looked at the pigments produced by Talaromyces australis (red) and Penicillium murcianum (yellow) and their effect upon the growth and pigment production of two species of Trichoderma and two species of Penicillium. Penicillium murcianum pigment inhibited growth and pigment production of all tested species at 3 mg/mL and higher. Results from this study indicate that P. murcianum colorants have the potential to inhibit growth and pigment production against other select ‘mold’ fungi. This holds potential not only for the wood preservation industry, but for the greater natural dye industry, especially in the area of antimicrobial textiles. Full article

Polyvinylidene fluoride (PVDF) films are widely used in sensors for their wide response frequency, good flexibility, low acoustic impedance, and chemical stability. In this work, PVDF/CaCl₂ piezoelectric films were prepared by an electro-assisted 3D printing method and used to form a multi-layer composite film sensor. The study found that the addition of CaCl₂ can effectively increase the β-phase content in the PVDF film and improve the piezoelectric and dielectric properties of the PVDF composite film sensors. When the content of CaCl₂ is 0.15 wt.%, the β-phase content of the PVDF/CaCl₂ composite film can reach the highest value of up to 48.47%, and the output voltage response of the sensor is 0.62 V at an input frequency of 10 Hz, 10 V voltage. The output voltage of PVDF composite film sensor with two and three layers is 1.306 and 1.693 times that of a single layer, respectively. The sensitivity of the multi-layer sensors has also been greatly improved. Full article

This paper discusses the results of a study focused on the nature of the interaction of Me-MeN-(Me,Mo,Al)N coatings (where Me = zirconium (Zr), titanium (Ti), or chromium (Cr)) with a contact medium based on the Ni-Cr system. The studies were carried out during the turning of nickel–chromium alloy at different cutting speeds. The hardness of the coatings was found, and their nanostructure and phase composition were studied. The experiments were conducted using transmission electron microscopy (TEM), X-ray diffraction (XRD), and selected area electron diffraction (SAED). According to the studies, at elevated cutting speeds, the highest wear resistance is demonstrated by the tools with the ZrN-based coating, while at lower cutting speeds, the tools with the TiN- and CrN-based coatings had higher wear resistance. At elevated cutting speeds, the experiments detected the active formation of oxides in the ZrN-based coating and less active formation of oxides in the CrN-based coating. No formation of oxides was detected in the TiN-based coating. The patterns of cracking in the coatings were also studied. Full article

The study systematically compares the low-cycle fatigue (LCF) behaviors of novel martensitic steel (22MnSi2CrMoNi) and maraging steel (00Ni18Co9Mo4Ti). Results show that the two types of tested steel have a similar cyclic deformation behavior. The cyclic softening resistance of 22MnSi2CrMoNi steel is slightly inferior to that of 00Ni18Co9Mo4Ti steel at a low total strain amplitude. However, the gap gradually disappears with the increase of the total strain amplitude. At the same plastic strain amplitude, the LCF lifetime of 22MnSi2CrMoNi steel is higher than that of 00Ni18Co9Mo4Ti steel. The retained austenite film between martensite lath and the existence of precipitated phase in matrix can effectively improve the fatigue lifetime of the two types of tested steel. Full article

Nine different environmentally friendly coatings were tested on natural and acetylated hornbeam wood, during natural weather exposure and xenon lamp irradiation. The coating performance of acetylated hornbeam, and the photostability properties of tested coatings were evaluated to offer suggestions regarding suitable and less-suitable coatings for the exterior use of acetylated hornbeam. On the one hand, acetylation decreased the coating absorbance of hornbeam. On the other hand, it made the wood more durable and dimensionally stable, all of which influences the outdoor performance of acetylated hornbeam. The color of acetylated hornbeam is not photostable; it brightens during photodegradation, and greys after leaching. For long-lasting color, acetylated hornbeam should be coated with dark pigmented stains and maintained regularly. Fungal degradation and cracking did not occur, but the wood is just as susceptible to wasp stripping as untreated hornbeam. In this study, 200-h-long xenon lamp irradiation resulted in a color similar to that caused by 1 month of weather exposure (April to May 2018, Sopron, Hungary). Full article

Organic solar cells (OSCs) have become a potential energy source for indoor light harvesting in recent years as they have witnessed a record power conversion efficiency (PCE) of over 30% under indoor lights. Among various strategies, interlayer engineering is one of the important factors in improving the performance of OSCs. Here, we reported an efficient OSC based on PM6:Y6 photoactive layer showing an excellent PCE of ~22% and ~14% under light-emitting diode (LED, 1000-lx) and 1-sun (AM1.5 G) conditions, respectively. The performance of OSCs was optimized by systematically investigating the optical, electrochemical, and morphological characteristics of three different cathode interlayers (CILs) named as: PEIE, ZnO, and ZnO/PEIE (bilayer). The high transmittance (~90%), suitable work function (~4.1 eV), and improved surface morphology (RMS: 2.61 nm) of the bilayer CIL contributes in improving the performance of OSCs. In addition, the suppressed charge recombination and improved charge carrier transport are attributed to high shunt resistance and appropriate energy levels alignment between photoactive layer and bilayer CIL. The findings in the study might provide guidelines for designing novel interlayers in the development of efficient OSCs for different illumination conditions. Full article

During the steel continuous casting, the submerged entry nozzle (SEN) plays a crucial role in the fluid characteristic of fluid steel, which further affects the slab quality. In this paper, a nozzle model is developed to study the influences of nozzle inclination, nozzle area ratio, and side hole aspect ratio on the fluid characteristic of fluid steel. The results show that when the nozzle angle increased from 10° to 20°, the impact points of the narrow surface were 0.402 m, 0.476 m, and 0.554 m away from the meniscus, respectively. In addition, when the nozzle area ratio increased from 0.96 to 1.16, it resulted in a significant decrease of the speed of high-temperature liquid steel flowing out of the nozzle. Moreover, when the side-hole aspect ratio was 1.47, the maximum turbulent kinetic energy of the free surface reached 0.00141 m² s⁻². Furthermore, when the aspect ratio was 1.67 and 1.84, a slight difference existed, and the maximum turbulent kinetic energy was almost 0.00095 m² s⁻². The proposed model can provide theoretical basis and guidance for nozzle optimization. Full article

WC-Co cermet materials serving as protective coatings are widely used in many fields. Conventional WC-17Co coatings were formed in high-velocity oxygen-fuel (HVOF), warm spraying (WS), and cold spraying (CS), respectively. Deposition behavior of a single WC-17Co particle, as well as the microstructure, microhardness, fracture toughness, and abrasive wear of WC-17Co coatings formed in various spraying ways were investigated. The results show that the deposition behavior of a single WC-17Co particle was different after it was deposited onto a Q235 steel substrate in various spraying ways. The WC-17Co splat deposited by HVOF showed a center hump and some molten areas, as well as some radial splashes presented at the edge of the splat. The WC-17Co splat deposited by WS presented a flattened morphology with no molten areas. However, the WC-17Co splat deposited by CS remained nearly spherical in shape and embedded into the substrate to a certain depth. All the WC-17Co coatings had the same phase compositions with that of feedstock. The microstructure of all the WC-17Co coatings was dense with no cracks or abscission phenomena between the coatings and substrate. Moreover, fine WC particles were formed in the coatings due to the fracture of coarse WC particles, and the content of fine WC particles in the cold-sprayed coating was significantly more than the other coatings. A stripe structure was formed by the slippage of fine WC particles with a plastic flow of Co binder in the warm-sprayed and cold-sprayed coatings. More fine WC particles, as well as the stripe structure, in the coatings were conducive to improve the microhardness and fracture toughness of the coating. The microhardness and fracture toughness of the cold-sprayed WC-17Co coating were the highest among the coatings. The main wear mechanism of all coatings was the groove and some peel-offs. The cold-sprayed WC-17Co coating with the lowest wear loss presented the highest wear resistance among the coatings. Full article