Search Results (48)

Difficult, extreme operating conditions of parabolic antennas under precipitation and sub-zero temperatures require the creation of effective heating systems. The purpose of the research is to develop a multilayer coating containing two metal-ceramic layers, epoxy composite layers, carbon fabric, and an outer layer of basalt fabric, which allows for effective heating of the antenna, and to study the properties of this coating. The multilayer coating was formed on an aluminum base that was subjected to abrasive jet processing. The first and second metal-ceramic layers, Al₂O₃ + 5% Al, which were applied by high-speed multi-chamber cumulative detonation spraying (CDS), respectively, provide maximum adhesion strength to the aluminum base and high adhesion strength to the third layer of the epoxy composite containing Al₂O₃. On this not-yet-polymerized layer of epoxy composite containing Al₂O₃, a layer of carbon fabric (impregnated with epoxy resin) was formed, which serves as a resistive heating element. On top of this carbon fabric, a layer of epoxy composite containing Cr₂O₃ and SiO₂ was applied. Next, basalt fabric was applied to this still-not-yet-polymerized layer. Then, the resulting layered coating was compacted and dried. To study this multilayer coating, X-ray analysis, light and raster scanning microscopy, and transmission electron microscopy were used. The thickness of the coating layers and microhardness were measured on transverse microsections. The adhesion strength of the metal-ceramic coating layers to the aluminum base was determined by both bending testing and peeling using the adhesive method. It was established that CDS provides the formation of metal-ceramic layers with a maximum fraction of lamellae and a microhardness of 7900–10,520 MPa. In these metal-ceramic layers, a dispersed subgrain structure, a uniform distribution of nanoparticles, and a gradient-free level of dislocation density are observed. Such a structure prevents the formation of local concentrators of internal stresses, thereby increasing the level of dispersion and substructural strengthening of the metal-ceramic layers’ material. The formation of materials with a nanostructure increases their strength and crack resistance. The effectiveness of using aluminum, chromium, and silicon oxides as nanofillers in epoxy composite layers was demonstrated. The presence of structures near the surface of these nanofillers, which differ from the properties of the epoxy matrix in the coating, was established. Such zones, specifically the outer surface layers (OSL), significantly affect the properties of the epoxy composite. The results of industrial tests showed the high performance of the multilayer coating during antenna heating. Full article

Despite their high specific capacity, magnetron-sputtered Si/Al thin films face rapid capacity decay due to stress-induced cracking, delamination, and detrimental electrolyte reactions. This study introduces a carbon-coated composite anode that overcomes these limitations, delivering superior reversible capacity, exceptional rate capability, and stable cycling performance. An electrochemical evaluation reveals that the CF-Si/Al@C-500-1h composite exhibits marked enhancements in capacity retention (43.5% after 100 cycles at 0.6 A·g⁻¹) and rate capability, maintaining 579.1 mAh·g⁻¹ at 3 A·g⁻¹ (1 C). The carbon layer enhances electrical conductivity, buffers volume expansion during lithiation/delithiation, and suppresses silicon aggregation and electrolyte side reactions. Coupled with an aluminum framework, this architecture ensures robust structural integrity and efficient lithium-ion transport. These advancements position CF-Si/Al@C-500-1h as a promising anode material for next-generation lithium-ion batteries, while insights into scalable fabrication and carbon integration strategies pave the way for practical applications. Full article

The effects of red mud on the microstructures and high-temperature tensile properties of the ZL109 aluminum alloy have been investigated. Red mud/ZL109-based composite materials with added red mud (a major byproduct of the aluminum industry), which has been coated with nickel by chemical deposition, have been prepared through gravity casting. The results show that the addition of red mud promotes the alloy’s microstructure and helps to uniformly distribute the eutectic silicon. It also increases the content of heat-resistant phases, such as the Q-Al₅Cu₂Mg₈Si₆ and γ-Al₇Cu₄Ni phases. These changes significantly enhance the alloy’s high-temperature tensile properties. The alloy with 1% (wt.%) red mud exhibits the best tensile strength at both room temperature and 350 °C, reaching 295.4 MPa and 143.3 MPa, respectively. The alloy with 1.5% (wt.%) red mud demonstrates excellent performance at 400 °C, achieving a tensile strength of 86.2 MPa through the cut-through method and Orowan mechanism. As a reinforcing material, red mud not only improves the high-temperature resistance of the aluminum alloy but also provides a way to recycle industrial waste. This study offers a new way to address the red mud waste problem and helps develop high-performance, heat-resistant aluminum alloys. It shows the potential of these alloys in high-temperature applications. Full article

High-Power Impulse Magnetron Sputtering (HiPIMS) has emerged as an excellent technology for producing high-quality nitride coatings, such as aluminum nitride (AlN), titanium nitride (TiN), chromium nitride (CrN), and silicon nitride (SiN), and composite nitride coatings such as titanium aluminum nitride (TiAlN), TiAlNiCN, etc. These coatings are known for their exceptional hardness, thermal stability, and corrosion resistance. These make them ideal for high-performance applications. HiPIMS distinguishes itself by generating highly ionized plasmas that facilitate intense ion bombardment, leading to nitride films with superior mechanical strength, durability, and enhanced thermal properties compared to traditional deposition techniques. Critical HiPIMS parameters, including pulse duration, substrate bias, and ion energy, are analyzed for their influence on enhancing coating density, adhesion, and hardness. The review contrasts HiPIMS with other deposition methods, highlighting its unique ability to create dense, uniform coatings with improved microstructures. While HiPIMS offers substantial benefits, it also poses challenges in scalability and process control. This review addresses these challenges and discusses hybrid, bipolar, and synchronized HiPIMS solutions designed to optimize nitride coating processes. Hybrid HiPIMS, for instance, combines HiPIMS with other sputtering techniques like DCMS or RF sputtering to achieve balanced deposition rates and high-quality film properties. Bipolar HiPIMS enhances process stability and film uniformity by alternating the polarity, which helps mitigate charge accumulation issues. Synchronized HiPIMS controls precise pulse timing to maximize ion energy impact and improve substrate interaction, further enhancing the structural properties of the coatings. Hence, to pave the way for future research and development in this area, insights of the HiPIMS have been presented that underline the role of HiPIMS in meeting the demanding requirements of advanced industrial applications. Overall, this review article comprehensively analyzes the recent strategies and technological innovations in HiPIMS and highlights the significant potential of HiPIMS for advancing the nitride coating field. Full article

In the Czochralski single-crystal silicon manufacturing industry, single-crystal furnaces often experience corrosion from silicon vapor, which reduces their operational lifespan. However, the preparation of metal coatings on the surface of C/C composites is challenging due to their low coefficient of thermal expansion and the intricate structure of carbon fibers. To address this issue and achieve high-quality alloy coatings, Ni-Al and Ni-Al/Si composite coatings are successfully prepared on the surface of C/C composites through a combination of electroplating and hot-dip plating, and their oxidation behavior at elevated temperatures is thoroughly investigated. The experimental results indicate that the Ni-Al composite coatings exhibit superior antioxidant properties compared to Ni coatings following thermal shock experiments, thereby significantly enhancing the antioxidant performance of C/C composites. This improvement is attributed to the preferential oxidation of surface aluminum, which forms a dense Al₂O₃ layer in aerobic and high-temperature environments, effectively preventing oxygen from reaching the underlying matrix. During the oxidation process, coating elements migrate outward along the concentration gradient, while oxygen molecules diffuse inward. Simultaneously, aluminum atoms diffuse inward, and Ni atoms diffuse outward, where they partially dissolve with oxygen. The inner coating’s Ni enhances the bonding of the coating by connecting the substrate to the outer layer. Meanwhile, the added Si in the Ni-Al/Si composite coating further improves the antioxidant properties of the coating. Full article

In this research, two intermediate layers were deposited on 316L stainless steel to improve the adhesion of diamond-like carbon (DLC) films, one composed of Ti_xAl and produced using the RF sputtering technique with three thicknesses, 100 nm, 200 nm, and 300 nm; the other, interlayer composed of amorphous hydrogenated silicon (a-Si:H). The DLC films were deposited using the pulsed-DC PECVD method with an active screen to achieve the AISI 316L/Ti_xAl//DLC and AISI 316L/TiₓAl/a-Si/DLC configurations. The binding energy between the substrate/Ti_xAl and Ti_xAl/a-Si:H was investigated via X-ray photoelectron spectroscopy with high-resolution spectra. The chemical composition and microstructure of the titanium–aluminum interlayers were investigated using energy-dispersive X-ray spectroscopy and X-ray diffraction, and the microstructure of the DLC coatings was studied using Raman spectroscopy. The coatings’ adherence was measured using scratch and indentation tests, and the hardness of the DLC coatings was determined with the nanoindentation test. The X-ray diffractograms did not allow the determination of any crystalline structure in the Ti_xAl interlayers. The XPS results showed that between the AISI 316L substrate and the Ti_xAl intermediate layer, Ti-O-Fe and FeAl₂O₄ were formed. On the other hand, at the Ti_xAl/a-Si:H interface, TiSi₂ and Al₂SiO₅ compounds were identified. The DLC coatings grew as hydrogenated amorphous carbon with a hydrogen content of around 30 at.% and a hardness of 24 GPa. The deposition methods used and the Ti_xAl/a-Si:H interlayers allowed the obtainment of adherent DLC coatings on AISI 316L stainless steel substrates. High critical load values of about 30 N were obtained. The novelty of this work is underscored by the absence of previous studies that thoroughly examine the bonds present in interlayers used as gradients to enhance the adhesion of DLC. Full article

This study investigates the corrosion products present on TiSi, AlTi, and WTi coatings deposited onto Ti6Al4V titanium alloy substrates using the RF sputtering PVD technique. Following deposition, the coatings underwent exposure to a temperature of 600 °C for 100 h. The corroded surfaces were meticulously characterized to identify the resultant corrosion products. Utilizing scanning electron microscopy (SEM), X-ray diffraction, optical profilometry, and XPS spectroscopy, the coatings were comprehensively examined. Furthermore, Raman mapping with multivariate analysis was employed to determine the spatial distribution of oxides in the coating post-high-temperature corrosion. Additionally, XPS spectroscopy unveiled the presence of species undetected by Raman spectroscopy, such as silicon oxide SiO₂, aluminum oxide Al₂O₃, and tungsten oxide WO₂, in oxidation studies on TiSi, AlTi, and WTi coatings, corroborated by XRD analysis. The results allowed us to propose the corrosion mechanisms of these coatings and to determine that the TiSi coating exhibits a superior high-temperature corrosion response compared to the AlTi and WTi coatings. The AlTi coating experiences aluminum depletion, whereas the WTi coating shows accumulations of tungsten oxides that resemble pitting. Full article

As a novel type of metal material emerging in recent years, high-entropy alloy boasts properties such as a simplified microstructure, high strength, high hardness and wear resistance. High-entropy alloys can use laser cladding to produce coatings that exhibit excellent metallurgical bonding with the substrate, thereby significantly improvement of the wear resistance of the material surface. In this paper, the research progress on improving the high-temperature wear resistance of high entropy alloy coatings (LC-HEACs) was mainly analyzed based on the effect of some added alloying elements and the presence of hard ceramic phases. Building on this foundation, the study primarily examines the impact of adding elements such as aluminum, titanium, copper, silicon, and molybdenum, along with hard ceramic particles like TiC, WC, and NbC, on the phase structure of coatings, high-temperature mechanisms, and the synergistic interactions between these elements. Additionally, it explores the potential of promising lubricating particles and introduces an innovative, highly efficient additive manufacturing technology known as extreme high-speed laser metal deposition (EHLMD). Finally, this paper summarizes the main difficulties involved in increasing the high-temperature wear resistance of LC-HEACs and some problems worthy of attention in the future development. Full article

Cavitation erosion poses a significant challenge in fluid systems like hydraulic turbines and ship propellers due to pulsed pressure from collapsing vapor bubbles. To combat this, various materials and surface engineering methods are employed. In this study, nano and micro scale particles of silicon carbide (SiC) or boron carbide (B₄C) were incorporated as reinforcement at 6% and 12% ratios, owing to their exceptional resistance to abrasive wear and high hardness. Microparticles were incorporated to assess the damage incurred during the tests in comparison to nanoparticles. Wear tests were conducted on both bulk samples and coated aluminum sheets with a 1mm of composite. Additionally, cavitation tests were performed on coated aluminum tips until stability of mass loss was achieved. The results indicated a distinct wear behavior between the coatings and the bulk samples. Overall, wear tended to be higher for the coated samples with nanocomposites than bulk, except for the nano-composite material containing 12% SiC and pure resin. With the coatings, higher percentages of nanometric particles correlated with increased wear. The coefficient of friction remained within the range of 0.4 to 0.5 for the coatings. Regarding the accumulated erosion in the cavitation tests for 100 min, it was observed that for all nanocomposite materials, it was lower than in pure resin. Particularly, the composite with 6% B₄C was slightly lower than the rest. In addition, the erosion rate was also lower for the composites. Full article

Environmentally friendly powder coatings which have the advantages of being VOC-free, low-cost, and high-efficiency with a high recovery rate have been attracting increasing research attention. The introduction of antibacterial agents into the powder coatings endows them with a capacity to kill bacteria and viruses on the surface of objects; additionally, this enables them to inhibit the indirect transmission of pathogenic microorganisms. Silver, possessing broad-spectrum, strong, and stable antibacterial properties, is considered to be a promising antibacterial material for use in coating applications. Carrier materials for active silver play an important role in its activity and stability. However, there is a lack of systematic studies on the effects of different types of carriers in such coating systems, especially in green powder coating systems. In this paper, we investigated two types of carriers for active silver agents: zeolite, i.e., Linde type A (LTA) zeolite and Y-type zeolite; clay-based materials, i.e., montmorillonite and vermiculite. All the agents showed high antibacterial activity, with antibacterial rates of over 99% as compared to commercial agents. Among the four agents, the Ag-LTA zeolite antimicrobial agent showed a reduction rate of over 99.99%; additionally, it maintained a reduction rate of 99% after seven washing cycles. Thus, this agent was demonstrated to have the highest effectiveness and high durability; these features can be attributed to the high silver content and small particle size. The LTA zeolite also provides a protective effect for silver ions, protecting them from reduction, due to the restriction of elemental silver formation within the confined interior space of the α-cage structure. The Y-type zeolite antimicrobial agent exhibited a slightly lower antimicrobial performance due to its higher silicon-to-aluminum ratio and its lower cation exchange capacity. Comparatively, antimicrobial agents utilizing clay-based carriers have lower cation exchange capacity, resulting in poorer antimicrobial effectiveness than zeolite carriers. In addition, silver loaded on clay-based materials is prone to detach from the carrier and undergo a reduction reaction, making the coating yellowish in color. This study first provides information on the roles of different types of carriers in powder coating systems; then, this information guides the selection of carriers for active silver for the development of efficient antimicrobial agents and coatings. Full article

Hot stamping (or press hardening) is a new technology that is widely used in the production of advanced high-strength steel parts for automotive applications. Electrochemical measurements, including potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), and accelerated corrosion tests (the neutral salt spray test and periodic immersion test) were conducted on press-hardened samples produced from uncoated (cold-rolled and cold strip production (CSP) hot-rolled) and Al–Si-coated press-hardened steels to elucidate their distinct anti-corrosion mechanisms. The cross-sectional micromorphology and element distribution of three types of press-hardened steels after a neutral salt spray test were observed using scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDAX). The corrosion resistance of Al–Si-coated press-hardened steel was found to be significantly diminished following the hot stamping process due to the presence of microcracks and elevated iron content in the coating subsequent to austenitizing heat treatment. On the other hand, the corrosion resistance of uncoated press-hardened sheets produced from cold-rolled and CSP hot-rolled press-hardened steel was found to be proximal due to their nearly identical composition and microstructure (fully martensite) after the hot stamping process. Considering the high efficiency and energy-saving properties of hot-rolled press-hardened steel, it holds the potential to replace cold-rolled and even aluminum–silicon-coated press-hardened steel in automobile manufacturing. Full article

Silicon nitride (Si₃N₄) particle-reinforced aluminum–copper (Al-Cu) alloy matrix composites have been prepared in our previous works and experimental result shows that they can be used as a new kind of water-lubricated materials. However, the wettability between Si₃N₄ ceramics and Al-Cu alloys is poor and the manufacturing process is usually carried out at a high temperature of 1100 °C. To overcome this shortcoming, a layer of nickel was deposited on the surface of Si₃N₄ particles, forming a core-shell structure. Thus, the interface bonding property between Si₃N₄ and Al-Cu alloy can be improved and the lower sintering temperature can be applied. Si₃N₄/Al-Cu alloy composites with different proportions of Ni-coated Si₃N₄ were fabricated by powder matrix metallurgy technology at 800 °C, and the water lubrication properties of the composite were investigated. The experimental results show that with the increase in the particle content (10 wt%–40 wt%), the microhardness of the composites increased first and then decreased, while the porosity increased continuously. A low friction coefficient (0.001–0.005) can be achieved for the composites with the lower particle content (10 wt%–20 wt%). The major wear mechanism changes from the mechanically dominated wear during the running-in process to the tribochemical wear at the low frictional stage. Full article

Solar cells play an increasing role in global electricity production, and it is critical to maximize their conversion efficiency to ensure the highest possible production. The number of photons entering the absorbing layer of the solar cell plays an important role in achieving a high conversion efficiency. Metal nanoparticles supporting localized surface plasmon resonances (LSPRs) have for years been suggested for increasing light in-coupling for solar cell applications. However, most studies have focused on materials exhibiting strong LSPRs, which often come with the drawback of considerable light absorption within the solar spectrum, limiting their applications and widespread use. Recently, aluminum (Al) nanoparticles have gained increasing interest due to their tuneable LSPRs in the ultraviolet and visible regions of the spectrum. In this study, we present an ideal configuration for maximizing light in-coupling into a standard textured crystalline silicon (c-Si) solar cell by determining the optimal Al nanoparticle and anti-reflection coating (ARC) parameters. The best-case parameters increase the number of photons absorbed by up to 3.3%. We give a complete description of the dominating light–matter interaction mechanisms leading to the enhancement and reveal that the increase is due to the nanoparticles optically exhibiting both particle- and thin-film characteristics, which has not been demonstrated in earlier works. Full article

This research paper focuses on the fabrication of a microstructure based on a natural structure pattern of hydrophobic properties using micro-milling technology, followed by an investigation of the dimensional accuracy, roughness, and replication of the fabricated microstructure. Design, modeling (CAD system), fabrication, and replication are the steps of this process. Knowledge of biomimetics was used to select the microstructure. The main research aim of the experiments is to verify and extend the applicability of conventional CNC manufacturing technologies to obtain a functional surface structure. The micro-milling was carried out on a conventional DMG MORI CNC machine, a CMX 600 V three-axis horizontal milling center, using an external high-frequency electric spindle clamped to the machine. The machined material was aluminum alloy EN AW 7075. The tool was a 0.1 mm diameter double-edged ball mill made of sintered carbide and coated with TiSiN. The cutting conditions were determined according to the tool manufacturer’s recommendations. To compare the achieved accuracies, the same microstructure was fabricated using PLA technology. For subsequent replication of the sample, the negative of the selected microstructure was created and machined. Subsequently, a positive microstructure was created using the silicone impression material by the replication process. This paper and the experiments performed extend the technical knowledge in the field of manufacturing surface functional structures and confirm the possibility of manufacturing the designed structures using chip and laser machining technology, with achieved discontinuities in the range of 3 to 50 μm. They also highlight the issues of replication of such structures with respect to critical manufacturing locations (geometrical parameters of the structures affecting the functional properties of the structure, venting, replica defects, etc.). Full article

Increasing the serviceability of industrial components intended for the petrochemical industry is possible through their superficial saturation with silicon (silicon cementation). Obtaining a silicon-rich surface coating results in a considerable increase in corrosion resistance, refractoriness, and wear resistance. One of the most economically convenient options for silicon cementation is pack siliconizing in powdery solid media. This paper presents the possibility of pack siliconizing that contains ferrosilicon (FeSi75C) and a thermite mixture (SiO₂ + Al) as active, silicon-providing components, in P265GH grade steel, which is frequently used in the petrochemical industry. The aim of the study was to determine the most suitable active component of the two that were analyzed and at the same time identify the processing conditions in which the siliconized coating has the greatest thickness, is free of porosity, and is in direct contact with the support. The use of experimental programming methods allowed the optimization of the operation to obtain the optimal solution. It was concluded that the thermite mixture is not compatible with pack siliconizing because it results in a superficial saturation predominantly composed of aluminum. When ferrosilicon is used as the active component, it determines the particularly intense formation kinetics of the non-porous siliconized coating with its maximum thickness being reached at high processing temperature values (over 1100 °C) with a proportion of 60% FeSi75 and, simultaneously, with the lowest possible proportion of ammonium chloride (max. 3%), which is the surface activation/cleaning component. Full article