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The article concerns the technology of layered castings made with a system where the base part is made of gray cast iron with flake graphite and the working part is made of high-chromium steel X46Cr13. The castings were produced using mould cavity preparation method utilizing a molding sand based on SiC. The idea of the research was to perform heat treatment of X46Cr13 steel directly in the casting mould, with the success of this approach guaranteed by selecting molding sand with appropriate physicochemical parameters. During the pouring and cooling of the mould, the temperature on the outer surface of the steel insert was recorded to check if it reached the required austenitization temperature. The castings were then examined for the quality of the bond between the gray cast iron base part and the steel working part, microstructure studies were conducted using light and scanning microscopes, and hardness was measured on the surface of X46Cr13 steel. Based on the conducted research, it was found that the high thermal conductivity of the molding sand made with a silicon carbide base disqualifies it for use in the analyzed technology of integrating heat treatment of X46Cr13 steel with the process of producing a bimetal system with gray cast iron. In the microstructure of the steel, in addition to martensite, pearlite and ferrite were present. Therefore, a satisfactory increase in the hardness of the working surface compared to the annealed state of X46Cr13 steel was not achieved, which ultimately confirmed that the hardening of the steel insert was unsuccessful.

This study was mainly performed in order to examine the properties of electric motor brushes (EMB). EMBs are electrically conductive and work under wear conditions due to direct contact with the moving part (rotor) of electric motors. In accordance with the scope of the study, EMB characteristics were investigated in two different groups and reproduced with a new technique at the end of this phase. New EMBs were produced via varying proportions of copper matrix, graphene, and silicon carbide reinforcements. The composite-alloy powder elements were carefully squeezed by a cold and single-axis hydraulic press under a pressure of 500 MPa (±5 MPa) following 8 hours of mechanical alloying (MA). The molded composite product (sample) was sintered at 900° C for 1 hour in a reducing gas atmosphere. 100 kPa spring pressure was tested on each sample thrice with 8, 16, 24, and 32 m/s rotational speeds and densities of 4, 8, 12, and 16 A/cm2. Following this process, the electrical conductivity, porosity, hardness, wear loss, surface roughness, and temperature changes were investigated for each sample. It was determined that the electrical conductivity decreased with increasing reinforcement ratio and, in terms of electrical conductivity, affected the brushes’ properties negatively.

Pristine SiC coating prepared by plasma spraying is difficult to achieve good ablation resistance at high temperature due to its weak SiO2 scale. Besides incorporation by ultra-high temperature ceramics, the modification of the SiC coating from its feedstock powder is necessary. In the current work, the mixed powders of SiC, Si and C, where the SiC was encapsulated and then carbonized by polydopamine, denoted as SiC@C–Si, were employed as the feedstocks, compared with the mixed case, i.e. SiC–Si–C. The SiC@C–Si coating exhibited superior anti-ablation properties, with a linear ablation rate of 0.62 μm/s, 57 % lower than the SiC–Si–C coating. This is attributed to the fact that nano-carbon formed by carbonization of polydopamine is more prone to reacting with Si than micron-sized C powder, thereby forming a dense microstructure after ablation. Besides, in-situ formed SiC by the depletion reaction increases the flow resistance and decelerates the failure of SiO2 film, thus improving the ablation resistance.

The stereolithography 3D printing technology provides a new technical solution for the preparation of complex structure SiC ceramic parts， but the characteristics of high light absorption and high refractive index of SiC lead to a common problem that printing is difficult to cure. SiO2 with low absorbance and low refractive index was added to SiC ceramic matrix powder as filler to improve the curing property and printing accuracy of SiC ceramic paste. The effects of different amounts of SiO2 on the rheology， stability and curing properties of the slurry and its mechanism were studied. The green body with high precision and good surface quality was prepared by stereolithography 3D printing technology， and the microstructure and properties of the green body were tested and analyzed. The results show that the adding SiO2 to the SiC slurry can reduce the viscosity， improve the stability， and improve the curing property of the slurry. The addition of SiO2 can significantly improve the surface roughness of the SiC green body and make the bending strength increase at first and decrease then.

Today, the emergence of composite structures can be considered a huge transformation on an industrial scale, especially in the transportation industry. Among all the structures made by the composite process, aluminum-based composites (AMMCs) are particularly popular both in the scientific and industrial fields. These structures are very light in weight and, at the same time, have significant strength. The ability to work with the machine in these structures is very high, and their plastic deformation is so high that they can be used in different industry sectors. Today, various methods are used to induce plastic deformation in aluminum-based composites (AMMCs). One of these methods is called aggregate accumulative press bonding (APB). The advantage of this method compared to other methods is that this method can create a homogeneous nanocomposite with ultra-fine grains. In the present study, the investigation of mechanical properties (MP's) of AA5083/5%SiC bulk composites fabricated via APB vs. pressing temperature (Temp) was conducted. All primary composite samples were fabricated via the stir-casting process (SCP). APB process was done on composite samples as a supplementary process. Finally, the effect of pressing Temp on the MP and microstructural properties (MSP) was investigated. The pressing Temp was varied between the ambient Temp's up to T = 300 °C. The MP were measured in this study by the Vickers micro-hardness (VMH) test, tensile test, and scanning electron microscopy (SEM). It was realized that the pressing Temp has a prominent effect on the MS and MP of fabricated 400°C. Samples fabricated at the ambient Temp have low ductility and high strength while for samples fabricated at T = 300 °C, the elongation and toughness values were higher than others. The TS of samples after 2 steps of APB at T = 200°C is 1.31 times more than that of fabricated at T = 300°C. Elongation was reduced sharply to 1.8% after the two steps at the ambient Temp, while it was 21% for the annealed AA5083.

The existing methods for preparing titanium matrix composites (TMCs) are less efficient and more expensive. An interlayer laser cladding SiC during arc-directed energy deposition Ti-6Al-4V was developed to efficiently prepare the TMCs, whose microstructure and mechanical properties were analysed to explore the mechanism for change. TiC and Ti5Si3 precipitated at grain boundaries, hindering the growth of α-Ti and β-grains and reducing the size difference between different deposition heights. The fine grain strengthening produced by the reduction in the size of the α phase and the prior β columnar grains, as well as the precipitation strengthening produced by the formed ceramic phase, increased the microhardness of the LCS component by 21.1%. The ceramic phase and the disappearance of the α/β interface phase increased the brittleness of the LCS component, whose tensile properties were slightly decreased than the directed energy deposited (DED) components.

AbstractThis paper investigates the effect of the SiC and triplex thermal aging treatment (TTAT) on the mechanical behavior of compound bars. The bars were fabricated by varying the SiC (2, 4 and 6 wt. %) in Al6061. Initially, bars were tested for hardness and compression strength in homogenized conditions. It is observed that as SiC is increased in the matrix, mechanical properties have improved. The bars with composite cores exhibited better properties as compared to bars with composite casing. For the bar having a composite core, with 2 wt. % SiC, the compression strength was 530.70 MPa, for the 4 wt.% SiC core it was 589.35 MPa and for the 6 wt.% SiC it was 691.88 MPa. Failure was progressive, with noticeable signs of failure, and the load-bearing ability was found to be fairly stable up to nearly 218 kN. Later, the bar with a 6 wt. % SiC core was subjected to TTAT, and surface hardness, compression strength, and interfacial shear strength were found to have increased by 11.2, 3.2 and 11.11%, respectively. SiC are the hard particles; reinforcing them in a soft matrix induces strain in the lattice and thus enhances the hardness of the composite. During aging, the diffusion of alloy atoms is blocked by the generated dislocations present around the SiC particles. Hence, the bars with a higher quantity of SiC in the composite core can be used for high load-bearing structural applications due to their superior mechanical properties as an alternative to the simple composite bars with the same SiC quantity.

Accident Tolerant Fuel (ATF) is a next-generation fuel technology developed to enhance the fundamental safety of light water reactors. Compared to existing standard fuel technologies, ATF technology can provide the same or better performance during normal operation, transient conditions, and accident scenarios of nuclear power plants, enhancing the ability of fuel elements to withstand severe accidents while reducing the cost of generating electricity over the licensed life of the plants. This paper introduces the definition, characteristics and thermal-hydraulic research objectives of ATF technology, systematically reviews the thermal-hydraulic research results of different ATF technologies in various aspects from the perspectives of near-term concepts (UO2-based composite fuels, coated Zr-based claddings, FeCrAl claddings) and long-term concepts (high-uranium-density UN fuels, FCM fuels, extruded metal fuels, SiC/SiC claddings), respectively. Mainly includes: improving fuel thermal conductivity, lowering fuel operating temperatures and stored energy, reducing fuel-cladding interactions, improving cladding-coolant reactions, reducing the production of flammable gases (e.g., hydrogen) and enhancing the retention of radioactive fission products. Finally, this paper points out the current shortcomings and challenges in the field of ATF thermal-hydraulic research and outlooks the potential future directions.

High-throughput computing has been widely used in the field of material design because of its feasibility, efficiency, accuracy and predictability. Fourteen new high-temperature SiC polymorphs were theoretically established via high-throughput screening, and density functional theory (DFT) was employed to investigate their physical properties. The new SiC polymorphs have mechanical and thermodynamic stability, and 10 of them can even maintain thermal stability at high temperatures up to 2000 K. The electronic band structure obtained by the Heyd–Scuseria–Ernzerhof (HSE06) hybrid functional shows that 13 of the new SiC polymorphs have a wide bandgap, 6 of which have a direct or quasi-direct bandgap. Notably, compared with those of 3C-SiC, the holes of I41/a-II SiC, I41/a-IV SiC, and P4/ncc-I SiC have lower effective masses in the [100] direction; in particular, the hole effective mass of P4/ncc-I SiC is only approximately 4.6 % of that of 3C-SiC. Owing to their direct wide bandgap, excellent thermal stability and low effective mass, the newly proposed SiC polymorphs have great application potential in the field of microelectronics.

Abstract Integrating resistive memory or neuromorphic memristors into mainstream silicon technology can be substantially facilitated if the memories are built in the back-end-of-line (BEOL) and stacked directly above the logic circuitries. Here we report a promising memristor employing a plasma-enhanced chemical vapour deposition (PECVD) bilayer of amorphous SiC/Si as device layer and Cu as an active electrode. Its endurance exceeds one billion cycles with an ON/OFF ratio of ca. two orders of magnitude. Resistance drift is observed in the first 200 million cycles, after which the devices settle with a coefficient of variation of ca. 10% for both the low and high resistance states. Ohmic conduction in the low resistance state is attributed to the formation of Cu conductive filaments inside the bilayer structure, where the nanoscale grain boundaries in the Si layer provide the pre-defined pathway for Cu ion migration. Rupture of the conductive filament leads to current conduction dominated by reverse bias Schottky emission. Multistate switching is achieved by precisely controlling the pulse conditions for potential neuromorphic computing applications. The PECVD deposition method employed here has been frequently used to deposit typical BEOL SiOC low-k interlayer dielectrics. This makes it a unique memristor system with great potential for integration.

Environment coatings are frequently considered, to improve the corrosion resistance of silicon carbide (SiC) in pressurized water reactor (PWR) and boiling water reactor (BWR) surroundings. Chromium (Cr) is one of the main candidate materials for coatings on zirconium-based alloys for accident-tolerant fuel (AFT) cladding. In this work, the magnetron sputtered Cr coatings on SiC substrates were irradiated by the 500 keV He+ ions at room temperature. Moreover, the microstructural characterization was conducted on the irradiated specimens by using scanning electron microscope (SEM), and transmission electron microscope (TEM). The scratch test showed that the coating-substrate adhesion decreased from 41 N to 28 N (∼31.7%) before and after the irradiation, maybe due to that the irradiation produced tensile strain in the coating and mesophase along the coating-substrate interface. It revealed that irradiation accelerated the migration and aggregation of C elements on the surface of the coating. After the 800 °C annealing for 20 min, massive Cr atoms diffused into the SiC matrix and reacted with Cr to form a chromium silicide interlayer. Some cracks were observed at the interface, being attributed to the Kirkendall effect. Therefore, it is very necessary to avoid the formation of chromium silicide interlayer and decrease swelling mismatch between the metal coatings and the SiC substrate for the actual application in nuclear systems.

The short-term (5 min) exposure to the supersonic flow of carbon dioxide plasma on ultrahigh-temperature ceramics of HfB2-30vol.%SiC composition has been studied. It was shown that, when established on the surface at a temperature of 1615–1655 °C, the beginning of the formation of an oxidized layer takes place. Raman spectroscopy and scanning electron microscopy studies showed that the formation of a porous SiC-depleted region is not possible under the HfO2-SiO2 surface oxide layer. Numerical modeling based on the Navier–Stokes equations and experimental probe measurements of the test conditions were performed. The desirability of continuing systematic studies on the behavior of ultrahigh-temperature ZrB2/HfB2-SiC ceramics, including those doped with various components under the influence of high-enthalpy gas flows, was noted.

HfCSiC-modified carbon/carbon composite (C/C–HfCSiC) sharp leading edges (SLEs) were prepared via precursor infiltration and pyrolysis for potential hypersonic applications. The effect of SiC proportion on the ablation behavior of the SLEs under oxyacetylene flames with 2.38 MW/m2 and 4.18 MW/m2 was investigated. The preferred sample with a volume ratio of HfC to SiC of 0.74 possessed almost zero degradation (linear recession rate 0.6 μm/s) up to a temperature of 2371 °C. As the temperature increases to 2527 °C in the latter condition, the SLE with less SiC (the volume ratio of HfC to SiC is 1.10) exhibited a linear recession rate of 1.03 μm/s during cyclic ablation of 3 × 40 s. Relatively more SiC addition is favorable under lower heat flux due to the better oxygen barrier performance of the scale. However, superior ablation resistance is available under higher heat flux with less SiC addition due to the higher thermal stability of the resulting oxide scale.

This study explores how machining parameters affect Surface Roughness (SR), Tool Wear Rate (TWR), and Material Removal Rate (MRR) during Electrical Discharge Machining (EDM) of a hybrid aluminum metal matrix composite (AMMC). The composite includes 6 % Silicon carbide (SiC) and 6 % Boron carbide (B4C) in an Aluminum 7075 (Al7075) matrix. A combined optimization approach was used to balance these factors, evaluating Pulse ON time, Current, Voltage, and Pulse OFF time. Response Surface Methodology (RSM) optimized single responses, while multi-response optimization employed a hybrid method combining the Entropy Weight Method (EWM), Taguchi approach, TOPSIS, and GRA. Analysis of Variance (ANOVA) assessed parameter significance, revealing substantial impacts on SR, MRR, and EWR. Based on TOPSIS and GRA, optimized parameters achieved a desirable balance: high MRR (0.4172, 0.5240 mm³/min), minimal EWR (0.0068, 0.0103 mm³/min), and acceptable SR (10.3877, 9.1924 μm) based on EWM-weighted priorities. Confirmation experiments validated a 15 % improvement in the closeness coefficient, and a 16 % improvement in the Grey relational grade, which considers combined SR, MRR, and EWR performance. Scanning Electron Microscope (SEM) analysis of surfaces machined with optimal parameters showed minimal debris, cracks, and no recast layer, indicating high surface integrity. This research enhances EDM optimization for AMMC, achieving efficiency in machining, minimizing tool wear, and meeting surface quality requirements.

Nickel alloys and composites are interesting engineering materials as a result of a combination of mechanical, corrosion and wear resistance at service temperatures that exceed those of steels and steel-based materials. The present study aimed at sintering Ni-graphite composites from NiO-SiC mixtures and investigate the in-situ formation of graphite. NiO powders were mixed with SiC (0, 3, 5 and 10 wt.%) and attrition-milled during 1 h. The mixtures were then granulated using 1.5 wt.% paraffin in hexane solution and uniaxially pressed under 400 MPa. The cylindrical pellets were then sintered at 1200 ºC. The sintered materials were characterized by density measurements, dilatometric and microstructural analyses, as well as Vickers microhardness. The results showed that Ni-graphite composites were successfully produced from NiO-SiC mixtures with full reduction of NiO and dissociation of SiC to form a Ni-Si matrix and graphite nodules.

Power Domain Non-Orthogonal Multiple Access (PD-NOMA) is a promising technique for future wireless networks. Currently, the growing number of researchers are addressing PD-NOMA issues. The great number of known results are based on the Shannon capacity theorem, assuming infinite code block length. However, they cannot be achieved in practice when modulation and coding schemes (MCS) with finite code block length are used. To solve this problem, we propose an approach which allows utilizing LTE MCSs in the link-level simulation of PD-NOMA. In this paper, we present an adaptive MCS map for a PD-NOMA system with two users, considering non-perfect Serial Interference Cancelation (SIC). In addition, we have developed a map for power allocation coefficients (PAC). The max-sum rate criterion and 10%-Block Error Rate constraint are utilized. The MCS and PAC maps allow access point to jointly and adaptively select MCS parameters for the users depending on their SNR values. The proposed MCS maps can be used in a link-level simulation of the PD-NOMA system to near-practical performance.

Friction stir spot welding (FSSW) is a prominent solid-state adhesion process. In the recent past, several investigations are performed for the property enhancement of FSSW welded joints especially on the mechanical and metallurgical characterization. In this work, an attempt has been made to analyze the effect of environmental conditions on the output quality characteristics of SiC reinforced Al6061-T6 welded joints, fabricated at optimal parametric setting. For this, welded joints are preserved at sub-zero temperature of −18 ± 2 °C for 90, 180, 270 and 360 days. Output quality characteristics in terms of tensile-shear and micro-hardness test in combination with microstructure analyses using SEM, EDS Mapping, and XRD analysis are emphasized. It is revealed that during sub-zero cooling, weld strength and micro-hardness of weldments increased over time. Additionally, a decrease in crystal size and increase in dislocation density are observed with increase in cooling period of weld joint, which eventually made suitable for extreme applications.

SiC-based ceramic matrix composites (SiC-CMC) are an ideal material for aeroengines with high thrust/mass ratio.In order to prevent the corrosion of SiC-CMC by gas (rich in H2O and O2) in the engine, it is necessary to prepare environmental barrier coatings (EBCs) with excellent water and oxygen corrosion resistance, gas erosion resistance and thermal shock resistance. Among many factors that evaluate the performance of EBCs, the bonding strength between EBCs and SiC-CMC matrix is an important indicator, but the limit value of the bonding strength has not been clearly explored.In this paper, main factors to control the bonding strength were studied in order to reach the highest value, including the SiC-CMC matrix state, the tensile strength limit of single crystal Si, and the preparation process of the Si bonding layer, etc. In the SiC-CMC/EBCs system, the interface between the SiC fiber cloth is the weakest part of the bonding strength, followed by the Si bonding layer. The bonding strength limit is 15 MPa, which is the tensile strength limit of single crystal Si in the [400] crystal direction. The bonding strength of the Si layer using atmospheric plasma spraying (APS) or high velocity oxygen-fuel(HVOF) is similar, which is lower than that of mullite or Yb2Si2O7 layer sprayed by the same process.

In-band full duplex (IBFD) communication systems have attracted much interest due to their ability to double the spectrum efficiency by simultaneously transmitting and receiving (STAR) over the same bandwidth. Modern communication technologies have to adapt to be able to meet the ongoing high demand capacity over existing radio channels. This paper proposes a system-level approach based on physical symmetry to improve the electromagnetic performance of a 3-port circulator. A system-level design consisting of two matched circulators connected in a differential configuration is proposed to cancel out residual RF scattering and leakage that causes self-interference in a STAR front-end. The method is validated using a custom designed microwave circulator based on microstrip technology, which forms a building block that operates in the 3–8 GHz band with 20 dB isolation. The proposed RF front-end operates within an extended band of 3–8 GHz while simultaneously exhibiting improvement in isolation by about 10 dB (isolation $30\pm 4$ dB) between the transmitter and the receiver ports of the STAR system.

As the demand for medium-voltage power semiconductors continues to rise, the super-cascode switch has emerged as a promising solution. This paper presents the design, implementation, and experimental evaluation of a 6.5 kV, 400 A super-cascode power module. This treatment includes an in-depth analysis of the theory of operation for this topology, as well as a set of design guidelines to facilitate the realization of practical implementations. To validate the functionality and performance of the realized prototype module, double-pulse test experiments were conducted under a wide range of operating conditions, deploying metrics specially targeted for the super-cascode switch. These experimental results demonstrate that adherence to the design guidelines provided in this paper yields a super-cascode switch with exceptional performance. In fact, the super-cascode module evaluated in this paper achieves switching performance on par with that of medium voltage SiC MOSFET modules, and far beyond that of medium voltage Si IGBT modules. Overall, this investigation contributes to the understanding of the factors driving the operation and performance of the super-cascode switch, especially under high current conditions.

The requirement of the upcoming sixth-generation (6G) wireless communication systems to significantly elevate the services of enhanced mobile broadband (eMBB) and massive machine-type communications (mMTC) necessitates the design and investigation of appropriate multiple access schemes. This paper investigates the impact of random source deployment on the performance of uplink systems, emphasizing the implications of non-orthogonality in contention-free and contention-based access schemes. For the latter scheme, we combine the strengths of slotted ALOHA and successive interference cancellation. Considering the advantages of breaking orthogonality in scenarios with random source deployment, we propose distinct policies tailored for mMTC, eMBB, and hybrid mMTC-eMBB scenarios by splitting the cell into rings. Furthermore, we derive closed-form expressions for the outage probability, which play a pivotal role in extracting the throughput of the sources in the considered scenarios. The paper offers a comprehensive analysis of the proposed approach, corroborated through simulations, shedding light on the potential of such protocols in future 6G wireless communication systems.

The super-cascode switch (SCS) has gained significant attention in the last decade due to its ability to achieve medium-voltage ratings using low-voltage semiconductors. However, there exists a notable absence of quantitative metrics to effectively evaluate the performance of the SCS. This gap exists because the behavior of the SCS is different from that of a traditional semiconductor switch, and traditional semiconductor performance metrics are not adequate for its evaluation. The present manuscript addresses this gap by introducing new figures of merit that are designed to evaluate the unique characteristics of the SCS. The practical value of these metrics is also demonstrated through a set of experimental studies. By applying these new figures of merit to one of the best-performing SCS configurations described previously in the literature, several opportunities for improvement are revealed. The SCS prototype described in this paper is evaluated experimentally at bus voltage levels up to 3.5 kV and current levels up to 200 A, demonstrating substantial performance improvements relative to the baseline configuration from the literature. These improvements are the result of iterative refinements to the balancing network, which are selected through a process that is informed by the application of the proposed figures of merit.

This work investigates the enhancement of dielectric properties of La2NiO4-CuO terpolymer nanocomposites using surface modified SiC nanoparticles as fillers. SiC nanoparticles were subjected to acid treatment and annealing at 1000 °C to tailor the surface chemistry. Acid treatment involved immersing the SiC powder in a mixture of H2SO4 and HNO3 acids and sonicating for 30 min, followed by stirring at 60 °C for 6 h. Annealing was carried out at 1000 °C for 2 h in an inert argon atmosphere. La2NiO4 and CuO nanoparticles were synthesized by sol-gel and precipitation techniques respectively, with average particle sizes of 20–40 nm and 10–15 nm confirmed by XRD and FESEM. Nanocomposites were fabricated by dispersing 2–10 wt% of untreated, acid treated and annealed SiC nanoparticles in a La2NiO4-CuO mixture solution, using PVDF as the polymer matrix. Impedance spectroscopy revealed that addition of 5 wt% acid treated SiC resulted in the highest dielectric constant of 42 at 1 kHz, in comparison to 25 for the unfilled polymer. This was attributed to increased interfacial polarization arising from uniform dispersion of nanoparticles and abundant charge trapping sites introduced by the SiC filler.

The potential of semiconducting, corrugated graphene, grown on silicon carbide, as an active element in chemosensors is studied in the present work. For this purpose, the adsorption of benzene, diazepam and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on the material’s surface was modeled. According to the graphene sheet bending and adsorbate–adsorbent distances, the heterostructure favors the ligands in the order of diazepam < benzene < TCDD. The apparent ambiguity in the results for diazepam is easy to explain. The abundance of lone pairs and π-electrons compensates for the low-symmetry, non-planar, far from optimal (adsorption-wise) geometry. The maximum band gap change in the heterostructure, caused by adsorption, is 0.02 eV. Intermolecular binding does not alter the HOMO–LUMO difference in benzene and TCDD by more than 0.01 eV. The completely planar molecules are not expected to undergo significant geometrical changes; hence, the alteration in their frontier orbitals is also minimal. The adsorption of diazepam, however, causes significant changes in the projected density of states of both structures in the complex. In conclusion, corrugated graphene is applicable as an active material in selective chemosensors for non-planar aromatic molecules.

Aluminum-based hybrid nanocomposites, namely the Al6061 alloy, have gained prominence in the scientific community due to their unique properties, such as high strength, low density, and good corrosion resistance. The production of these nanocomposites involves incorporating reinforcing nanoparticles into the matrix to improve its mechanical and thermal properties. The Al6061 hybrid nanocomposites were manufactured by conventional powder metallurgy (cold pressing and sintering). Ceramic silicon carbide (SiC) nanoparticles and carbon nanotubes (CNTs) were used as reinforcements. The nanocomposites were produced using different reinforcement amounts (0.50, 0.75, 1.00, and 1.50 wt.%) and sintered from 540 to 620 °C for 120 min. The characterization of the Al6061 hybrid nanocomposites involved the analysis of their mechanical properties, such as hardness and tensile strength, as well as their micro- and nanometric structures. Techniques such as optical microscopy (OM) and scanning electron microscopy (SEM) with electron backscatter diffraction (EBSD) were used to study the distribution of nanoparticles, the grain size of the microstructure, and the presence of defects in the matrix. The microstructural evaluation revealed significant grain refinement and greater homogeneity in the hybrid nanocomposites reinforced with 0.75 wt.% of SiC and CNTs, resulting in better mechanical performance. Tensile tests showed that the Al6061/CNT/SiC hybrid composite had the highest tensile strength of 104 MPa, compared to 63 MPa for the unreinforced Al6061 matrix. The results showed that adding 0.75% SiC nanoparticles and CNTs can significantly improve the properties of Al6061 (65% in the tensile strength). However, some nanoparticle agglomeration remains one of the challenges in manufacturing these nanocomposites; therefore, the expected increase in mechanical properties is not observed.

This paper presents a comprehensive exploration of advanced beamforming techniques tailored for millimeter-wave (mm-Wave) communication systems. In response to the burgeoning demand for higher data rates, coupled with the constraints of power consumption and hardware complexity, this study focuses on developing a hybrid beamforming framework optimized for downlink scenarios, specifically targeting groups of users based on the approximate symmetry of their channels. The primary innovation of this research lies in leveraging the symmetry of channels among near users to develop a group-based successive interference cancellation (SIC) algorithm. Unlike traditional approaches that address interference on a per-user basis, this algorithm utilizes channel symmetry within clusters of users to reduce computational complexity and improve the efficiency of SIC. By grouping users with symmetrical channel characteristics, the algorithm simplifies the interference management process while maintaining system performance. The proposed system demonstrates notable advantages over existing non-linear algorithms through extensive simulations and performance evaluations, particularly in terms of spectral efficiency and computational complexity. In this study, we further emphasize the importance of balancing spectral efficiency improvements with reduced computational demands, offering a nuanced trade-off that accommodates various operational requirements. The flexible optimization framework provided showcases the system’s adaptability to diverse deployment scenarios and network configurations.

In this study, Al-Si-Cu-Mg composites reinforced with Silicon carbide (SiC) particles and/or Carbon nanotubes (CNTs) were fabricated using semi-solid stirring casting technology (SSC). The aim of the study was to investigate the influence of SiC and/or CNTs on the mechanical properties, microstructural evolution, and deformation mechanisms of the Al-Si-Cu-Mg alloy. The findings indicated that the presence of SiC/CNTs in the composite had a significant effect on refining the α-Al phase and altering its grain orientation. Additionally, the results obtained from EBSD and TEM revealed that the microstructure of the Al-Si-Cu-Mg-SiC/CNTs hybrid composite (HAMC) underwent dynamic recrystallization (DRX) and static recrystallization (SRX), resulting in a fine equiaxed recrystallized structure. This process also led to the formation of high-angle grain boundaries (HAGBs) through dislocation rearrangement. The SiC particles were evenly distributed within the matrix, ensuring good interface bonding between SiC and α-Al phases. Moreover, the CNTs reacted with the matrix, resulting in the in-situ formation of the Al4C3 phase at the interface. The addition of SiC/CNTs significantly increased the tensile strength of HAMC at 25°C and 250°C, from 319MPa and 178MPa to 438MPa and 331MPa. Examination of the fracture surface of the hybrid composite unveiled that void formation occurred primarily at the regions surrounding the matrix-particle interface.

This study investigates a novel methodology to intricately craft a HAMMC and thoroughly examine its multifaceted mechanical and tribological characteristics. By combining silicon carbide (SiC) and fly ash as reinforcements, a unique identity is bestowed upon this hybrid composite, enhancing its structural integrity and functional attributes. Stir casting is the chosen methodology for fabricating this composite, favored for its economic viability and suitability for large-scale manufacturing. In this research, the emphasis is on developing a cost-effective composite that not only meets stringent economic considerations but also exhibits improved material properties. Within the realm of hybrid metal matrix composites, the well-regarded Al6061 takes on the role of the matrix material, while the synergistic inclusion of fly ash and SiC serves as reinforcing constituents. Three specimens with compostion 90% Al6061 + 5% SiC +5% Fly ash, 90% Al6061 + 10% SiC +6% Fly ash and 90% Al6061 + 15% SiC +7% Fly ash were fabricated. To unravel the intricacies of the fabricated Al6061 metal matrix composite, comprehensive tests are employed. These tests, including the Pin-on Disc test, Scratch test, Rockwell Hardness test, and Charpy Impact test, collectively work to unveil the nuanced tribological and mechanical behaviors encapsulated within this innovative alloy. The results indicated significant improvement in wear resistance in specimen comprising 78% Al6061 + 15% SiC +7% Fly Ash and volumetric loss found to have 0.96 g. Superior hardness characteristics and enhanced abrasion resistance found in 78% Al6061 + 15% SiC +7% Fly Ash than other two specimens. The highest impact strength exhibited in 90% Al 6,061 + 5% SiC +5% Fly ash specimen.

An insightful understanding of the formation mechanism of process-inherent defects and deformation is increasingly important for the property evaluation and structural design of ceramic matrix composites (CMCs). For this purpose, a coupled thermal–diffusive–mechanical modeling approach was proposed by considering three important phenomena that occur during the pyrolysis process for manufacturing CMCs: variations of the physical and mechanical properties of the constituents, generation and diffusive of pyrolysis gas, and multiple thermal deformations. The synergistic effects of these three phenomena on the stress, damage development, microstructural morphology, and process deformation of SiC matrix composites were investigated using finite-element simulations. This new approach was validated by comparing the simulation and experimental results. Significant volume shrinkage of the matrix during the polymer-to-ceramic transformation resulted in large tensile stresses and subsequent highly fragmented microstructure in CMCs. The pyrolysis-gas-induced expansion on the matrix under a damage state may yield a positive process deformation of CMCs at the macroscale, overcoming the effects of the volume shrinkage of the bulk matrix at the microscale. The modeling approach is expected to guide high-quality manufacturing of CMCs and comprehensive studies of structure–processing–property relationships.

In this study, the effects of Mg on the formation of He bubbles and diffusion behavior of He atoms in cubic silicon carbide (3C–SiC) were investigated by irradiation and annealing experiments as well as first-principles calculations. TEM results indicated that two damage bands were formed in He&Mg irradiated SiC. During annealing, Mg could prevent He atoms from diffusing to the surface, resulting in the formation of the He bubbles in the deeper areas far from Mg-implanted regions, which is helpful in avoiding surface blisters. First-principles calculations were then performed to explore the effects of Mg on the He behavior in SiC. The solution energy, binding energy charge density, bond length, and crystal orbital Hamiltonian population of these elements were calculated to identify their states. The results suggested that the binding capacity between He and Mg was weak, and Mg could increase the diffusion energy barrier of He. Ab initio molecular dynamics (AIMD) simulation showed that Mg could make He in a high-energy unstable state, and force He atom to move toward the vacancy away from Mg, which explains the experimental results.

The advantages of SiC MOSFETs (metal-oxide semiconductor field effect transistor) make this technology attractive for space, avionics and high-energy accelerator applications. However, the current commercial technologies are still susceptible to single event effects (SEEs) and latent damages induced by the radiation environment. In commercial SiC MOSFETs exposed to heavy ions, two types of latent damages were experimentally observed. One type is observed at bias voltages just below the degradation onset voltage and involves the gate oxide. The other type of damage was observed at bias voltages below the single event burnout (SEB) limit and which was attributed to changes in the silicon carbide lattice. The key parameter of SiC MOSFET, JFET region width, has been considered as the main influence factor of SEEs of SiC MOSFET. Aiming at this influence factor, SEE experiment was carried out on 12 kV SiC MOSFET devices with different JFET region widths of the same structure to investigate the influence of different JFET region widths on the device’s SEEs burning threshold voltage, leakage degradation threshold voltage, and the device performance under negative gate voltage conditions, and the test results show that the leakage degradation threshold voltage increases with the decrease of the JFET region width. Reducing the JFET region width of the device can effectively improve the SEEs resistance of the device, this effect is also observed under negative gate voltage bias conditions. Under negative gate voltage bias conditions, the effect of JFET region width on the SEEs of the device is reduced by the negative gate voltage. Sentaurus TCAD is used for simulation, and the simulation results confirm that the JFET region width and the negative gate voltage bias affect the accumulation of holes in the JFET region under the oxide layer, which in turn affects the oxide layer field strength, and thus affects the single event leakage degradation of the device. It is also demonstrated that SEB is caused by a localized energy pulse due to ion collisional ionization, followed by avalanche multiplication, which generates a large amount of Joule heat and leads to permanent structural damage in the device. The whole burn-in process does not correlate well with the JFET region width, and all changes in the JFET region width do not have a significant effect on the burn-in voltage, which is in line with the experimental results. The JFET region width is only one of the factors affecting the single event leakage degradation effect. The in-depth research will be carried out, with the help of advanced TCAD software to find out the intrinsic mechanism causing this phenomenon, in order to provide technological support for the radiation hardening of SiC power devices.

Este artigo investiga o uso da informação contábil a partir dos Sistemas de Informação Contábil (SIC) na gestão das micro e pequenas empresas que atuam no segmento da educação infantil, ensino médio e técnico, em instituições privadas do município de Camaragibe, em Pernambuco. Para isso, foi realizada uma pesquisa descritiva, de abordagem quantitativa, no qual foi realizado um censo e posterior envio de questionário aos gestores escolares objeto deste estudo. Obteve-se 38,2% de retorno e os resultados revelaram, dentre outros aspectos, que a maioria dos estabelecimentos pesquisados possuem contador, sendo este, em sua maioria, terceirizados. O estudo evidenciou também a relevância, confiabilidade e compreensibilidade das informações contábeis geradas pelo SIC para a maioria dos gestores pesquisados. O nível de conhecimento sobre o SIC percebido pela maioria dos gestores é bom. Quanto ao nível de percepção do SIC relativo à facilidade de uso, melhora do fluxo de trabalho, redução de erros, fornecimento de relatórios gerenciais para a tomada de decisão, dentre outras variáveis, a maioria dos respondentes questionados ‘concordam’ que o SIC promove tais atribuições, evidenciando assim, a atenção com as atividades gerenciais da escola, no sentido de identificar as dificuldades e promover a busca de soluções adequadas. Esta pesquisa pode ser um importante instrumento de orientação aos gestores de micro e pequenas empresas, em instituições privadas de ensino, para que possam compreender as lacunas existentes na gestão organizacional, através do SIC, e assim possam implementar estratégias e ações mais eficazes para em um melhor desempenho organizacional.

In this investigation, the Mg-0.5Zn-0.5Zr/4%SiC composite fabricated by the stir casting method was subjected to multi-pass friction stir processing (MFSP) to evaluate its microstructure, hardness, dry-sliding wear, and friction properties in comparison to those of the as-cast composite (ACC). Microstructural observations revealed the formation of a Mg matrix with average grain size (AGS) of 107 ± 12 μm, uneven dispersion (agglomeration) of SiC particles in the structure, and the formation of Zr-rich phase with the chemical composition of Zr:78.42, C:19.46, Mg:1.86, and Zn:0.26 wt%, ZrC, as well as some new formed carbide-based phases mostly propagated along the grain boundaries. On the other hand, the MFSP implementation led to a significant microstructural modification, i.e., in the optimum circumstance, the AGS and SiC particle size in the stir zone was reduced by 97.28 % (107–2.9 μm) and 67.69 % (21.33–6.89 μm), respectively, and the density of the composite increased from 1.669 to 1.774 gr/cm3. According to dry-sliding wear test results, applying FSP and increasing the pass number to three reduced the wear rate and coefficient of friction (COF) of the composites by about 45 % and 24 %, respectively, compared to those of ACC. The wear resistance enhancement was ascribed to wear mechanisms changing from delamination/adhesion/severe abrasion to mild abrasion wear, which stemmed from the formation of a stable O-rich tribolayer on the worn surface of FSPed samples.

The oxidation behavior and kinetics of (Zr, Ti)(C, N)–SiC ceramics subjected to a temperature of 850 °C-950 °C (typical operating temperatures range of Generation-IV nuclear reactors) for 1–4 h are investigated via X-ray diffraction, scanning electron microscopy, and weight gain testing. The results show that the microstructures of the ceramics after oxidation comprises primarily of m-(Zr, Ti)O2, c-(Zr, Ti)O2, and SiO2. After adding Si, the oxidation layer appears as a two-layer structure with both external and internal layers. The oxidation order of (Zr, Ti)(C, N)–SiC ceramics at 850 °C-950 °C is ZrSi > (Zr, Ti)(C, N) > SiC. Unoxidized SiC forms a “core-shell” structure with a dense external layer of SiO2. The dual effect of small SiO2 particles occupying cracks and the “core-shell” structure of SiC–SiO2 withstanding stresses can inhibit the propagation of cracks and reduce the porosity of the oxide layer. The oxidation of Z5T and Z5T5S exhibits linear oxidation kinetics, whereas the oxidation of Z5T10S and Z5T20S results in quasi-parabolic oxidation. By adding Si, the oxidation activation energy of Z5T20S (with the addition of 20 mol% Si) increases by 174 % compared to that of Z5T ceramic, thus improving the oxidation resistance of (Zr, Ti)(C, N)-based ceramics at 850 °C-950 °C.

Copper matrix composite reinforced with SiC exhibits high electrical and thermal conductivity, as well as superior mechanical properties, making it a potential candidate for thermal management applications. There has been rapid progress in the understanding of Cu–SiC metal matrix composites during the past decade. To accomplish this, powder metallurgy, casting, selective laser melting, composite electroforming technology, and electrodeposition methods have been employed. The optimum cutting conditions for fabrication of Cu–SiC metal matrix composites are still being explored. In recent years, friction stir processing (FSP) has become increasingly popular in the fabrication of composites. FSP is capable of microstructural engineering in Cu–SiC systems. In light of the fact that the electrical/thermal conductivity and mechanical performance of Cu–SiC composites depend on microstructural characteristics such as SiC distribution, grain size, grain orientation, density of dislocations, and bulk density, it seems important to study the effect of manufacturing conditions on microstructure in detail. In this study, the influence of FSP parameters such as rotational and traversal speeds, the number of FSP passes, and the pin profile as well as the characteristics of SiC powder are discussed in detail with regard to macro- and microstructure, hardness, strength, tribological, and electrical properties of FSPed Cu–SiC composites.

Abstract Background To study the potential role of the C2PAC index (a ratio of soluble type C lectin-like receptor 2 level sCLEC-2 and platelet count) in sepsis-induced coagulopathy with the possibility of using this index as an early predictor in sepsis and sepsis-induced coagulopathy. Methods Our case–control study included a total of 86 participants divided into 2 groups: group I is the case group consisting of 56 patients of sepsis or septic shock and group II (control group) of 30 healthy persons: sex and age-matched healthy individuals. All patients were subjected to assessment of C lectin domain family 2 receptor (sCLEC2), by enzyme-linked immunosorbent assay ELIZA kit, then C2PAC index (a ratio of soluble type C lectin-like receptor 2 level sCLEC-2 and platelet count) was calculated using the platelet count. Results Our study demonstrated that sCLEC-2 levels and C2PAC in group I were higher than in group II (p value

With the development of power conversion systems or bidirectional grid-connected inverters characterized by high DC voltage, high efficiency, and high-power density, high-switching-frequency SiC power switches are being widely used, and these require a short computational time of control algorithm. Based on the sector judgment of a space voltage vector and the midpoint potential control balancing of a DC bus, an improved finite control set method prediction control (FCS-MPC) method was proposed for a T-type three-level PCS. This improved FCS-MPC first judges the sector of the space voltage vector and locates the position of the corresponding large sector according to phase lock information; then, it analyzes the sampled voltage of the upper and lower bus capacitors to obtain the midpoint potential situation and selects appropriate small vectors based on the midpoint potential situation. This simple improved strategy can reduce the computational complexity of traditional MPC for rolling optimization, resulting in a reduction in the vectors from 27 to 8. A SiC-based 10 kW bidirectional PCS prototype verified the improved FCS-MPC, and the computational time was reduced about by 56% in comparison to traditional FCS-MPC.

In efforts to fulfill the objectives of taking part in pragmatic cooperation in the Arctic, constructing the “Silk Road on Ice”, and ensuring ships’ safety and risk assessment in the Arctic, the two biggest hazards, which concern ships’ navigation in the Arctic, are wind and sea ice. Sea ice can result in a ship being besieged or crashing into an iceberg, endangering both human and property safety. Meanwhile, light winds can assist ships in breaking free of a sea-ice siege, whereas strong winds can hinder ships’ navigation. In this work, we first calculated the spatial and temporal characteristics of a number of indicators, including Arctic wind speed, sea-ice density, the frequency of different wind directions, the frequency of a sea-ice density of less than 20%, the frequency of strong winds of force six or above, etc. Using the ERA5 wind field and the SSMI/S sea-ice data, and applying statistical techniques, we then conducted a joint analysis to determine the correlation coefficients between the frequencies of various wind directions, the frequency of strong winds and its impact on the density of sea ice, the frequency of a sea-ice concentration (SIC) of less than 20%, and the correlation coefficient between winds and sea-ice density. In doing so, we determined importance of factoring the wind’s contribution into sea-ice analysis.

Chip bonding, an essential process in power semiconductor device packaging, commonly includes welding and nano-silver sintering. Currently, most of the research on chip bonding technology focuses on the thermal stress analysis of tin–lead solder and nano-silver pressure-assisted sintering, whereas research on the thermal stress analysis of the nano-silver pressureless sintering process is more limited. In this study, the pressureless sintering process of nano-silver was studied using finite element software, with nano-silver as an interconnect material. Using the control variable method, we analyzed the influences of sintering temperature, cooling rate, solder paste thickness, and solder paste area on the residual stress and warping deformation of power devices. In addition, orthogonal experiments were designed to optimize the parameters and determine the optimal combination of the process parameters. The results showed that the maximum residual stress of the module appeared on the connection surface between the power chip and the nano-silver solder paste layer. The module warping deformation was convex warping. The residual stress of the solder layer increased with the increase in sintering temperature and cooling rate. It decreased with the increase in coating thickness. With the increase in the coating area, it showed a wave change. Each parameter influenced the stress of the solder layer in this descending order: sintering temperature, cooling rate, solder paste area, and solder paste thickness. The residual stress of the nano-silver layer was 24.83 MPa under the optimal combination of the process parameters and was reduced by 29.38% compared with the original value of 35.162 MPa.

This paper reviews sintered silver (s-Ag) die-attach materials for wide band gap (WBG) semiconductor packaging. WBG devices that die-attach with s-Ag have attracted a lot of attention owing to their low energy loss and high temperature operation capabilities. For their practical operation, a reliability design should be established based on the failure of physics of the s-Ag die layer. This paper first focuses on the material characteristics of the s-Ag and tensile mechanical properties. Then, the s-Ag die-attach reliability is assessed with high-temperature storage, power cycling, and thermal shock tests. Each fracture mode was discussed by considering both the fracture surface analysis results and its mechanical properties. Finally, the effective reliability design parameters of the s-Ag die layer are introduced.

This paper introduces a method for producing red copper glaze by adding copper oxide (CuO) and silicon carbide (SiC) additives to the base glaze. SiC created a reducing environment in situ and allowed the glaze to be sintered in an oxidizing furnace environment. Nanocrystals are the determinants of the red color of the glaze. The CuO reduction reaction temperature range of SiC produces a reducing environment in the glaze as detected by the method (DSC). The functional group and phase of nanocrystals were determined by Fourier transform infrared (FT-IR) and X-ray diffraction (XRD) spectroscopy.

The 0.5Y2O3/Al2O3-Cu/30Mo3SiC and 0.3GO-0.5Y2O3/Al2O3-Cu/30Mo3SiC composites were fabricated by fast hot press sintering. Hot compression tests of the composites were carried out using the Gleeble-1500 simulator at 0.001–10 s−1 strain rates and 650–950 °C deformation temperatures. The effects of doped reduced graphene oxide (rGO) on the hot deformation behavior and microstructure of 0.5Y2O3/Al2O3-Cu/30Mo3SiC composites were investigated. Trace of molybdenum carbide (MoC) layers/nanoparticles formed in-situ at the rGO-Cu/Mo interface, which is beneficial to the interfacial bonding of the composite. The enhanced flow stress and activation energy of hot deformation is attributed to the addition of the rGO. The activation energy of the composites was improved by 11% with the addition of rGO. The dislocation density and texture orientation ratio decrease at higher deformation temperatures.

With the current-assisted bonding technology, the rapid brazing of SiC ceramics was realized at 1125℃ with CoFeCrNiCuTi2 high-entropy alloy as the bonding layer material, which improves the bonding efficiency and ensures the full diffusion of elements. The influence of brazing temperature on the microstructure and mechanical properties of the bonding interface was studied. The results show that the obtained brazed joint has no obvious defects and the weld microstructure is mainly composed of high-entropy FCC, TiC phase and Cr23C6 phase. The formation of TiC reaction layer with dense interface inhibits the decomposition of high-entropy alloy and the formation of intermetallic compounds to a certain extent, and relieves the thermal stress between interface matrix SiC and high-entropy alloy filler. At the same time, due to the delayed diffusion effect of high-entropy alloy filler, the filler in the center of weld still keeps the FCC structure of high-entropy alloy. The mechanical test shows that the strength of brazed joint decreases at first and then increases. When the joining temperature is 1125℃, the maximum bending strength of SiC joint is 37 MPa, which is higher than that of ordinary Ni-based filler by about 21.3 MPa.

Particle-reinforced Mg matrix composites possess excellent mechanical and physical properties. In this study, a new processing technique, semisolid injection molding, was employed to fabricate SiCp/AZ91D composites. The microstructure and mechanical properties of the as-molded composites were investigated. The SiC particles were found to be uniformly distributed in the metal matrix and no agglomeration was observed. The presence of small voids next to the SiC particles was observed. The microhardness of the composites decreases with the increase of SiC content, and initially decreases and then increases to a stable level with the increase of casting temperature. The 2.5 wt% SiCp/AZ91D composite has the highest tensile strength, up to 10% higher than AZ91D and 18% higher than the 1 wt% SiCp/AZ91D composite. A large number of small dimples and spherical voids, formed after unmelted Mg particles were pulled out of the matrix, were observed on the tensile fracture surface. This study demonstrates that semisolid injection molding is a valuable technique for the manufacture of particle-reinforced metal matrix composites.

Highlights The intimate NG@SiC heterostructure has been constructed via a direct thermal decomposition method. The NG@SiC heterostructure anode delivers enhanced capacity and cycling stability both in the half-cell and in the full cell. DFT analysis reveals that this NG@SiC anode possesses lower lithium-ion adsorption energy and higher charge and discharge rates.

ABSTRACTA new technique using impedance spectroscopy was developed to estimate the oxidation kinetics of the pyrolytic carbon interphase layer in SiCf/SiC ceramic matrix composites. The AC impedance Nyquist plot showed two semicircles that were curve-fitted using an equivalent circuit with two constant-phase element components. The analysis results revealed that the capacitance in the low-frequency region decreased with increasing oxidation time, whereas that in the high-frequency region remained relatively constant. This change in the capacitance in the low-frequency region was associated with the thickness of the oxidized SiO2 layer. This study might make a significant contribution to the literature, which has mostly focused on the characterization of ceramic matrix composites through measurements of mechanical properties. The limitations and potential applications of the developed method were also elucidated.

The borosilicate glass was used to join reaction bonded silicon carbide through two steps, namely: laser cladding and low-temperature heat treatment. The wettability and microstructure of the laser cladding glass layer were examined, while joint microstructure and strength were analyzed at various temperatures and times. The results show that the laser cladding layer improved the wetting of glass on the substrate, formed a good interfacial bond, and reduced the joining temperature. The joints primarily consist of the glass phase, the boron-rich phase, and a few crystals. The high-strength joints obtained after heating the joint interface at 950 °C for 30 min had a flexural strength of 250 ± 20 MPa, a 68% improvement compared with direct connection under the same conditions. The joints also exhibit good thermal shock resistance and high-temperature strength. At 400 °C (thermal shock temperature) and 600 °C (test temperature), the residual flexural strengths were 122 ± 25 and 152 ± 12 MPa, respectively.

The demanding material quality criteria in the automotive and aerospace industries have recently had an impact on the development of lightweight aluminium alloys. The choice and application of metal-matrix composites as structural materials in this context are known to offer a variety of benefits. These benefits include the ability to combine high elastic modulus, toughness, and impact resistance; minimum sensitivity to change in temperature or thermal shock; durability of the surface is good; moisture absorption leads to a potential issue while minimum exposure which leads to environmental degradation; and improved fabricability with conventional metalworking equipment. Aluminium metal matrix composites (AMMCs) are a potential material for advanced structural, aviation, aerospace, marine, and defense applications, as well as for the automotive sector and other related fields, due to their outstanding combination of qualities. The stir casting procedure is used to create an aluminium metal matrix composite (AMMC), which is the most efficient way to do so. In this study, the aluminium alloy 7075 is strengthened using neem leaf powder and SiC. The Vickers hardness examination method is used to govern the hardness of hybrid composites. Eventually, the mechanical and tribological properties of the composites were assessed, and their relationship to the composites' matching microstructure and wear was addressed.

The physical and chemical stabilities of SiC and heat-resistant steel were assessed by the diffusion couple method under vacuum at 1200 °C, which is a commonly used condition in magnesium metallurgy. High-temperature visualization instruments were used and Differential thermal analysis (DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermodynamic analyses were performed to verify the relevant mechanism. The reaction between SiC and heat-resistant steel can be divided into two stages: solid–solid and solid–liquid reactions. The solid–solid interfacial reaction produces graphite, which hinders the interfacial reaction. The interfacial reaction simultaneously generates silicides (NiSi, Ni2Si, and Ni3Si) with low melting points and transforms the reaction interface into a solid–liquid interface. The formation of the liquid phase promotes the dissolution and diffusion of carbon, leading to the accelerated corrosion of SiC and low-temperature melting of steel. Supersaturated carbon precipitates in the melt in the form of nanowires or nanotubes are catalyzed by Fe/Ni. Herein, a general model describing the direct interfacial reaction mechanism of SiC and heat-resistant steel is proposed to explain the reaction process under vacuum.

Abstract Efficient photocatalytic reduction of CO2 to high‐calorific‐value CH4, an ideal target product, is a blueprint for C1 industry relevance and carbon neutrality, but it also faces great challenges. Herein, we demonstrate unprecedented hybrid SiC photocatalysts modified by Fe‐based cocatalyst, which are prepared via a facile impregnation‐reduction method, featuring an optimized local electronic structure. It exhibits a superior photocatalytic carbon‐based products yield of 30.0 µmol g−1 h−1 and achieves a record CH4 selectivity of up to 94.3%, which highlights the effectiveness of electron‐rich Fe cocatalyst for boosting photocatalytic performance and selectivity. Specifically, the synergistic effects of directional migration of photogenerated electrons and strong π‐back bonding on low‐valence Fe effectively strengthen the adsorption and activation of reactants and intermediates in the CO2 → CH4 pathway. This study inspires an effective strategy for enhancing the multielectron reduction capacity of semiconductor photocatalysts with low‐cost Fe instead of noble metals as cocatalysts.