Search

The current study goals to create of PS-SiC-Al2O3 multifunctional nanocomposites films as a promising nanomaterials to exploit in futuristic nanoelectronics and optical fields. By comparing with other nanocomposites films, the PS-SiC-Al2O3 films have high absorption for UV-radiation, flexible, low band gap, and inexpensive. The microstructure and optical characteristics of PS-SiC-Al2O3 films were investigated. The microstructure and morphological properties included FTIR and OM. The realized results indicated that the values absorbance for PS-SiC-Al2O3 films are high at NIR and UV spectrums. These results build the films of PS-SiC-Al2O3 are promising for NIR sensing, UV shielding and optoelectronics approaches. The increment ratio of PS absorbance is 30.9% for λ = 320 nm and SiC-Al2O3 content is 2.4 wt.%. The PS band gap is 3.8 eV and its reduced to 3.13 eV with increasing SiC-Al2O3 NPs content to 2.4 wt.%.. This performance leads to make the PS-SiC-Al2O3 films are welcomed in various optoelectronics and photonics fields. The optical factors: extinction coefficient; absorption coefficient; real and imaginary dielectric constants, refractive index; and optical conductivity of PS were enhanced with increasing SiC-Al2O3 NPs content; these results of lead to made the PS-SiC-Al2O3 films are suitable for optical fields. Finally, the achieved results confirmed that the PS-SiC-Al2O3 films could be as a key for promising nanoelectronics and optical fields. [ABSTRACT FROM AUTHOR]

Additive manufacturing technology is being developed for manufacturing SiC ceramic parts with designed shape and microstructure. In this study, direct ink writing (DIW) was adopted to print SiC ceramic parts. To avoid incorporating volatile organic solvents or water, a SiC ceramic precursor liquid polycarbosilane (LPCS) was used as the binder of SiC powder and the rheological adjustment additive. The content of LPCS with the content and diameter of SiC powder were optimized to improve the fluidity of slurry, increase its ceramic yield and reduce its shrinkage during pyrolysis. According to the results of rheological analysis and shrinkage during pyrolysis, 78 wt% SiC powders composed of 40 nm SiC powder and 5 μm SiC powder in a ratio of 1:6 was appropriate. For achieving rapid solidification rate of the slurry at low temperature, a free‐radical initiator which can trigger the crosslinking of allyl group on LPCS was incorporated. According to the results of rheology, DSC and FT-IR, the preferred platform temperature for fast curing of DIW slurry was 150 °C. As the slurry accumulated layer by layer on heating platform, the cured green bodies were successfully prepared. After pyrolysis to 1200 °C, SiC ceramic parts were obtained with only 4.43 % linear shrinkage associated with the precursor-to-ceramic conversion. Because the shrinkage was limited, no obvious deformation or crack was found. [ABSTRACT FROM AUTHOR]

Yttrium-containing ceramics exhibit excellent resistance to water-oxygen corrosion, making them an attractive choice as the modified matrix for SiC f /SiC composites. However, the oxidation products of yttrium-containing ceramics are complex and vary widely in performance. In this study, YSOC ceramics, which are composed of yttrium silicate, SiO 2 , and SiC, were prepared using Y 2 O 3 , SiO 2 , SiC, and Li 2 CO 3. This research investigated the effects of high temperatures, air oxidation, and water-oxygen corrosion on the phase compositions of YSOC ceramics. The influence of environmental factors on the synthesis and decomposition of yttrium silicate was analyzed. Moreover, the study explored the compatibility of different oxidation products with SiC. The results suggest that Y 2 SiO 5 and Y 2 Si 2 O 7 are formed through the low eutectic of SiO 2 , Y 2 O 3 , and Li 2 CO 3. The high SiO 2 content likely contributes to the relatively low formation temperature of Y 2 Si 2 O 7. In the oxidizing environment, Y 2 SiO 5 reacts with SiO 2 to produce Y 2 Si 2 O 7. Conversely, in the water vapor-containing atmosphere, Y 2 Si 2 O 7 undergoes hydrolysis to form Y 2 SiO 5. Y 2 Si 2 O 7 displays a reduced elastic modulus in comparison to SiC fibers and exhibits favorable physical and chemical compatibility with SiC fibers. However, the hydrolysis of Y 2 Si 2 O 7 may potentially affect the water-oxygen corrosion resistance of the ceramics. These findings will significantly advance research and enhance understanding of the water-oxygen corrosion behaviors of yttrium-containing matrix-modified composites. [ABSTRACT FROM AUTHOR]

Room‐temperature (RT) 2D van der Waals (vdW) ferromagnets hold immense promise for next‐generation spintronic devices for information storage and processing. To achieve high‐density energy‐efficient spintronic devices, it is essential to understand the local magnetic properties of RT 2D vdW magnets. In this work, noninvasive in situ stray field detection is realized in vdW‐layered ferromagnet Fe3GaTe2 using divacancy spins quantum sensor in silicon carbide (SiC) at RT. The structural features and magnetic properties of the Fe3GaTe2 are characterized utilizing X‐ray diffraction, scanning tsransmission electron microscopy, Raman spectrum, magnetization, and magneto‐transport measurements. Further detailed analysis of temperature‐ and magnetic field‐dependent optically detected magnetic resonances of the PL6 divacancy near the Fe3GaTe2 reveal that, the Curie temperature (Tc) of Fe3GaTe2 is ∼360 K, and the magnetization increases with external magnetic fields. Additionally, spin relaxometry technology is employed to probe the magnetic fluctuations of Fe3GaTe2, revealing a peak in the spin relaxation rate around the Tc. These experiments give insights into the intriguing local magnetic properties of 2D vdW RT ferromagnet Fe3GaTe2 and pave the way for the application of SiC quantum sensors in noninvasive in situ stray field detection of related 2D vdW magnets. [ABSTRACT FROM AUTHOR]

The primary purpose of this study is to gain a deeper understanding of the structure and mechanics of an ex-situ A356/Cu-coated with different weight percentages (x: 1, 3) of SiC stir-cast metal matrix composite. This study aims to improve silicon carbide's wetting and adhesion characteristics by fabricating a Cu-coated composite utilizing an electrolytic deposition technique based on aluminum. This green manufacturing method significantly reduces environmental impact compared to traditional coating processes, a crucial aspect in today's world. Examination of the optical microstructure of the SiC composite revealed a clustering of reinforcements within the matrix, potentially resulting from additional barriers formed during the stirring process that impede the movement of SiC particles. Furthermore, incorporating copper-coated SiC reinforcement led to a more even distribution of reinforcements in the matrix. The ultimate tensile strength, yield strength, and hardness of the 3 wt% copper-coated metal matrix composite cast are 225.97 MPa, 130.27 MPa, and 76.5 BHN, respectively, demonstrating superior mechanical properties compared to the other cast composites. The study opens potential paths for further advancements in composite technology. [ABSTRACT FROM AUTHOR]

A novel α/β SiC-(Ti, Nb)B 2 toughened (Ti, Nb)C-based composites was fabricated by reactive hot pressing with TiC, NbB 2 and Si powders at 1500 °C and 1600 °C, respectively. The influence of NbB 2 , Si content, and sintering temperature on the microstructure and mechanical properties of the composite was investigated. The intermediate product NbC reacts with Si to form NbSi 2 and β-SiC phases. With addition of 10 mol% NbB 2 , a toughening phase α-SiC was formed. During the reaction process, insufficient diffusion of Nb atoms in TiC leads to the formation of a specific "core-shell" microstructure, which improves the flexural strength of the composite ceramics. The (Ti, Nb)C has a specific crystallographic orientation relationship with NbSi 2 and α-SiC. The high-density stacking faults and ordered structures in β-SiC crystals enhances its hardness. The rod-shaped α-SiC and plate-like (Ti, Nb)B 2 by in situ reactions effectively improve the fracture toughness of the composites. TiC-32 mol% Si-10 mol% NbB 2 (raw powder composition) sintered at 1600 °C has excellent comprehensive mechanical properties, with fracture toughness, flexural strength, and Vickers hardness of 5.45 MPa·m1/2, 665 MPa, and 22 GPa, respectively, which provide a new insight into the optimization strength and toughness of TiC-based composites. In addition, under high temperature oxidation of 1000∼1200 °C, the 30NB (54 mol% TiC-16 mol% Si-30 mol% NbB 2) sample has better high-temperature oxidation resistance than the 30ZB (54 mol% TiC-16 mol% Si-30 mol% ZrB 2) sample. [ABSTRACT FROM AUTHOR]

High-entropy carbides-SiC biphasic ceramics demonstrate outstanding mechanical and oxidation resistance properties. However, previous studies have predominantly focused on fabricating dense monolithic high-entropy carbides-SiC biphasic ceramics, with limited attention given to the production of high-purity, narrow particles size distribution high-entropy carbides-SiC biphasic ceramic powders. In this study, we successfully synthesized high-entropy carbides-SiC biphasic ceramic powders, specifically (Hf 0.25 Zr 0.25 Ta 0.25 Ti 0.25)C-SiC, utilizing the polymer-derived-ceramic (PDC) route employing transition metal alcohol solution and methyltrimethoxysilane. The resultant powders exhibited an average particle size of ∼15 μm, with a narrow particle size distribution. Furthermore, variations in the heat treatment temperature demonstrated minimal impact on the particle size, while maintain compositional homogenous from nanoscale to microscale, and exhibiting low oxygen content less than 1.01 %. The introduction of the SiC phase also enhances the dynamic oxidation resistance of the high-entropy carbides. This pioneering work will not only provide a novel approach for obtaining other high-entropy carbides and SiC biphasic ceramic powder but also offers prospects for large-scale fabrication in industrial. [ABSTRACT FROM AUTHOR]

SiC particles coated with Ti-Si-C layer were prepared by the molten salt synthesis method using NaCl-KCl eutectic mixture as the reaction medium and Ti metal powder as the Ti source. The synthesis was conducted under static argon atmosphere at 900 °C for 1–3 h. The post-synthesis treatment included dissolution of salts in hot water, followed by ultrasonic dispersion and sedimentation procedures. The thickness of the Ti-Si-C layer varied from 0.1 to 0.9 μm as the ratio of Ti to SiC components in the starting mixture changed from 0.05 to 0.4. The layer contained mainly nanocrystalline Ti 5 Si 3 , minor phases were TiC and Ti 3 SiC 2. The as-prepared powders were hot pressed under 30 MPa at 1700 °C. The densification behavior of the samples during hot pressing as well as changes both in phase composition and in microstructure were studied. The flexural strength of the hot-pressed samples increased with an increase in the Ti:SiC molar ratio, giving the value as high as 213 ± 20 MPa for the sample with Ti/SiC = 0.4. [ABSTRACT FROM AUTHOR]

This study aims to extend the work-life of diamond-cutting segments and to economize the operating cost of diamond-cutting tools. In order to achieve this object, bronze matrix sandwich segments reinforced with SiC and B 4 C were produced utilizing the hot pressing technique. In the term of the cutting segments, it is favorable that the outer layers are wear-resistant and the middle layer is tough. SEM and XRD analysis were used to determine the microstructural properties. Mechanical properties were evaluated by conducting hardness, wear, cutting performance, and three-point bending tests. The cutting performance of the segments was determined by turning andesite marble. SEM examinations showed that SiC and B 4 C grains were homogeneously distributed in the bronze matrix. The highest hardness value was 113.9 HB in the B 4 C reinforced sandwich segment. The reciprocating wear test findings indicated that the matrix exhibited the lowest wear rate in the B 4 C reinforced sandwich composite segment, followed by the hybrid sandwich composite segment. The lowest amount of cutting loss after turning andesite stone was achieved in the SiC, and B 4 C reinforced hybrid sandwich composite segment. The cutting performance of the hybrid sandwich composite segment increased by 46.15 % compared to the conventional segment without additives. The highest value of the transverse rupture strength of the specimens was 380 MPa for the B 4 C reinforced sandwich composite segment and 352 MPa for the hybrid sandwich composite segment. Considering all the tests and analyses, the hybrid sandwich composite segment sample may be the most suitable for diamond-cutting tools. [ABSTRACT FROM AUTHOR]

AbstractThe present investigation focuses on the synthesis of mono (AA5052/SiC and AA5052/graphene) and hybrid (AA5052/SiC/graphene) surface composites using friction stir processing (FSP). This work examines the synergistic effect of SiC and graphene on the fabricated surface composites. Macro/microstructure, microhardness, and wear test analysis were done on these samples, and the results were compared with the base material AA5052-H32. The microstructure analysis showed that the distribution of reinforcement particles in the aluminum matrix is made more uniform by adding hard SiC with graphene nanoparticles, which can reduce the occurrence of particle clustering and agglomeration. As a result, the smallest grain size of 11.2 µm and the highest microhardness obtained was 84.1 HV obtained in hybrid surface composites. Consequently, the hybrid surface composites obtained more improved wear properties than mono surface composites. Thus, the hybrid surface composites achieved the lowest average friction coefficient of 0.304. [ABSTRACT FROM AUTHOR]

In recent years, SiC aerogels have attracted considerable research interest owing to their excellent high-temperature resistance. It is crucial to research and improve the thermal stability of SiC aerogels under long and multiple heat treatments. Herein, we develop a series of monolithic SiC aerogels with a density of 0.23–0.28 g cm−3, low-thermal linear shrinkage of 21%–27 %, and high compressive strength of 0.38–0.60 MPa by designing a novel core–net structure. The resulting aerogels exhibit excellent thermal insulation thermostability and high-temperature reusability. Thermal conductivities of 0.0455–0.0678 W K−1 m−1 and 0.0934–0.1313 W K−1 m−1 were achieved at 40 °C and 900 °C, respectively. Following three consecutive heat treatments using a butane spray gun for 2000 s, the macromorphology exhibited no change, and the backside temperature was 230 °C. The results demonstrate an effective solution to reuse aerogels as long-lasting high-temperature insulation materials. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Statistical hypothesis testing, as formalized by 20th century statisticians and taught in college statistics courses, has been a cornerstone of 100 years of scientific progress. Nevertheless, the methodology is increasingly questioned in many scientific disciplines. We demonstrate in this paper how many of the worrisome aspects of statistical hypothesis testing can be ameliorated with concepts and methods from evidential analysis. The model family we treat is the familiar normal linear model with fixed effects, embracing multiple regression and analysis of variance, a warhorse of everyday science in labs and field stations. Questions about study design, the applicability of the null hypothesis, the effect size, error probabilities, evidence strength, and model misspecification become more naturally housed in an evidential setting. We provide a completely worked example featuring a two-way analysis of variance. [ABSTRACT FROM AUTHOR]

In this study, SiC quantum dots (SiC‐QD's) are studied, and some roundish SiC‐QD's with the incorporation of defects by removing a carbon or silicon atom are considered. Fourteen configurations are modeled in which the position of the silicon or carbon defect for each configuration is changed, considering that due to the chemical composition, it allows more Si atoms or more C atoms on the QD surface. All calculations are performed using the Density Functional Theory (DFT) methodology. The electronic exchange correlation is treated using the Generalized Gradient Approximation (GGA) with the Revised Perdew–Burke–Ernzerhof (RPBE) functional. The electronic energy levels of each configuration are calculated as well as the partial density of states to know the origin of the energy gap in each quantum dot. The final step is to analyze the energy formation to determine chemical stability. [ABSTRACT FROM AUTHOR]

A combination of fluorescent SiC (f‐SiC) and porous f‐SiC is a promising phosphor material for pure white light emission. Herein, the anodic oxidation condition is optimized to produce porous f‐SiC. Furthermore, a hybridly packaged white light emitting diode (LED) package composed of f‐SiC/porous f‐SiC stacks with a nitride‐based NUV‐LED as an excitation source is fabricated. A distinct pure white light emission and the peak luminous efficacy of 11.6 lm W−1 at a forward current of 10 mA in the NUV‐LED are observed. At the peak luminous efficacy, the estimated internal quantum efficiency of the f‐SiC/porous f‐SiC stacks is ≈80% as the package involved several types of optical and energy losses. [ABSTRACT FROM AUTHOR]

A method for improving the properties of the deposited metal in wire arc additive manufacturing of Al–Si alloy is proposed here, which introduces SiC ceramic particles into the side-axis wire feed. The effects of SiC ceramic particles on the macroscopic morphology, microstructure and mechanical properties, corrosion resistance, and wear resistance of deposited metals were studied. The results show that the introduction of SiC particles will not affect the surface-forming quality of the deposited metal; this is likely due to the stable droplet transfer and no splashing. The transverse and longitudinal tensile strengths are increased by 10.1 % and 11.3 %, respectively, while the corresponding elongations are increased by 33.1 % and 47.2 %, respectively. Further, the corrosion resistance and wear resistance of Al–Si alloy deposited metals containing SiC are improved. The (100) base surface has strong texture characteristics along the deposition direction X0, and the maximum polar density decreases to 13.63, which indicates that SiC promotes the transformation of columnar crystals to equiaxial crystals. The interface between SiC and Al is non-coherent, and the performance improvement lies in the enhanced dispersion distribution and load transfer of SiC. A ring structure was prepared using double-wire arc additive manufacturing technology, and the feasibility of side-axis wire feeding technology was verified. [ABSTRACT FROM AUTHOR]

Synthesis of porous ceramic materials based on fine SiC with sintering silicon oxide and magnesia binders at T = 800–1300 °C is considered. Special attention is paid to the influence of the shape and morphology of the initial powder particles on structural parameters and characteristics of porous ceramic materials. The SiC membranes sintered at 1000–1300 °C had average pore sizes of 0.5–1 μm, open porosity - up to 50 %, bending strength - up to 48.5 MPa and high water permeance - up to 7890 l⋅m−2⋅h−1⋅bar−1. The established filtration efficiency was ∼99 % in the case of screening out model particles of D 50 = 0.5 μm in size with maintaining stable permeance and physico-mechanical characteristics after multiple filtration-regeneration cycles. Comprehension of the initial powders morphology impact on the synthesized porous ceramics parameters makes it possible to forecast and ensure the preset structural, dimensional and physico-mechanical parameters of the materials under study properly. This work can be used for practical low-cost production of highly efficient SiC membranes for micro- and ultrafiltration processes, as well as base for catalysts. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A high‐entropy rare‐earth disilicate (Er0.25Y0.25Ho0.25Yb0.25)2Si2O7 (hereinafter referred to as (EYHY)2Si2O7) ceramic was synthesized by a heat treatment process combined with spark plasma sintering. According to the experimental results, (EYHY)2Si2O7 presents good phase stability and low thermal conductivity ([1.48–2.35] W∙m−1∙K−1) from room temperature to 1200°C. Its coefficient of thermal expansion is (3.89–5.32) × 10−6 K−1 from 200 to 1400°C, similar to SiC‐based materials ([4.5–5.5] × 10−6 K−1). Due to the multiple doping effects, (EYHY)2Si2O7 exhibits outstanding corrosion resistance performance in water‐vapor corrosion tests. Its weight loss is 1.79 mg/cm2 after corrosion at 1600°C for 30 h in the presence of 50% H2O‐50% O2, which is lower than the corresponding four single components Re2Si2O7 (Er2Si2O7, Y2Si2O7, Ho2Si2O7, and Yb2Si2O7) under the same conditions. Therefore, high‐entropy (EYHY)2Si2O7 ceramics are regarded as potential environmental barrier coatings materials for SiC ceramic matrix composites. [ABSTRACT FROM AUTHOR]

Silicon carbide (SiC) is widely used in various industrial fields for its excellent properties. Vat photopolymerization (VP) technology stands out in the fabrication of SiC ceramics due to its enhanced design flexibility and capability to produce intricate geometries. However, the excessive residual carbon content in VP technology directly affects the sintering performance of SiC ceramics, leading to cracking and deformation defects. To address this issue, we systematically studied the residual carbon content of SiC under different debinding atmospheres in forming by VP technology. We found that the debinding atmosphere can effectively control the residual carbon content in SiC ceramics. Residual carbon exists in samples with a lower degree of defect, promotes grain growth, reduces neck size, and results in flexural strength of 253.13 MPa after pressureless sintering. This research promotes the application of VP technology in SiC ceramics and opens up a new avenue for the development of high-performance SiC ceramics. [ABSTRACT FROM AUTHOR]

High flight speed of hypersonic vehicles will push thermal insulation composites to achieve balanced enhancement of high porosity with increasing load-bearing capability. Herein, hierarchically porous SiC(rGO) polymer-derived ceramics (PDCs) with lightweight, heat-insulating, anti-ablative and tough engineered merits, are designed from polycarbosilane-vinyltriethoxysilane-graphene oxide precursors by re-pyrolysis/graphite-assisted decarburization. Graphite pore-forming agents tightly coupled with SiO x C y /C free (rGO) by C-dangling bonds, can inhibit SiO x C y decomposition, increase ceramic network disorder and expedite concurrent removal of C free. SiO 2 generated from Si-dangling oxidation bonding, efficiently densifies framework to retain mechanical performances, and meanwhile creates more interfaces to enhance phonon scattering. Such structure similar to nodular cast iron confers low thermal conductivity (0.11 W·m-1·K-1), particularly, fully preserves good compressive strength (5.4 MPa) for SiC(rGO) 40%. Under both cyclic butane flame ablation (∼1300 °C) and long-term oxidation for 7200 s, self-healing effect of SiO 2 imbues products with good structural integrity, shedding light on the opportunity to apply any thermal protection system. [Display omitted] • Hierarchically porous SiC(rGO) PDCs were ingeniously in-situ constructed. • Re-pyrolysis/graphite-assisted decarburization is a new structural design strategy. • The obtained products own well-balance between thermal insulation and load bearing. • Graphite-assisted interfacial interactions aims at strengthening ceramic framework. • Self-healing effect of SiO 2 can be promptly activated under flame scouring. [ABSTRACT FROM AUTHOR]

Multi-phase UHTCs are favoured for their superior ablation resistance and mechanical properties. In this work, to improve the efficiency and decrease the sintering temperature and pressure, the (Zr, Hf)C and SiC hybrid nanocrystalline particles were prepared via the sol-gel method combining carbothermal reduction at 1600 °C. Utilizing their high sinterability, a relative density of 96.1% (Zr, Hf) C–SiC composite was obtained at the conditions of 1900 °C and 30 MPa using SPS technology. XPS and FT-IR results demonstrate that Zr, Hf, and Si were successfully trapped in the cross-linking structure of the precursors. Precursors of Zr, Hf, and Si reached a molecular-level mixture in the gel phase. SEM, XPS, and XRD characterization showed that the Si–C bond was formed preferentially, leading to the emergence of SiC whiskers and SiC wrapped (Zr, Hf)C with increasing temperature. And, the (Zr, Hf)C can be easily generated during solid solution reaction. Eventually, a nanoscale mixture of (Zr, Hf)C and SiC particles was successfully obtained at 1600 °C. The hardness and compressive strength of the (Zr, Hf)C–SiC composite were 12.94 GPa and 622 MPa, respectively. Comparing usual sintering processes (over 2000 °C and 35 MPa), the reason for the improved sinterability can be attributed to the high sintering activity of the (Zr, Hf)C and SiC hybrid particles, and the existence of the solid solution and nano-SiC. [ABSTRACT FROM AUTHOR]

Although flash sintering (FS) is an effective method for rapidly preparing ceramics, FS of non-oxide ceramics at room temperature (RT) has not yet been achieved. In this study, we developed a feasible method for FS of SiC at room temperature (RT). A dog-bone-shape SiC sample prepared without using any sintering aid achieved a relative density of 96.5 % after sintering in a low-pressure Ar atmosphere for 60 s. Arc heating, which was constrained by the height of an alumina plate fixed above the sample, increased the conductivity of the sample, which then reached the stable stage of FS. The sintered sample exhibited a typical 6H–SiC crystal structure, which was consistent with that of the raw powder. The proposed FS method, based on constraining the arc using an alumina plate under a low-pressure inert gas atmosphere, provides a reference for developing further advanced RT FS strategies for non-oxide ceramics with low conductivities at RT. [ABSTRACT FROM AUTHOR]

Surface grinding is a widely employed finishing process in industrial sectors dedicated to achieve desired Surface characteristics of components. This study experimentally investigates the impact of the grinding parameters pertaining to the surface characteristics of Inconel 800, which is a nickel-iron-chromium alloy extensively used in high-temperature applications. Various commercially available grinding wheels were employed to grind Inconel800 under different grinding conditions. The ground surfaces were comprehensively analyzed using surface roughness measurements, Three-dimensional profilometry, optical microscopy, findings from XRD and SEM reveal that grinding parameters and wheel characteristics significantly impact the surface texture, topographical features, residual stress, and surface morphology of the machined nickel alloy.. The insights from this investigation contribute to the understanding of the grinding behavior of nickel-based superalloys and provide a basis for optimizing the grinding process for enhanced surface integrity. The findings are valuable for industries dealing with the machining of high-performance nickel alloy components. [ABSTRACT FROM AUTHOR]

Owing to their excellent thermal conductivity (TC), boron nitride nanosheet (BNNS)-filled polymer composite films have aroused great interest in their use for heat dissipation in the electronics industry. However, the application of BNNS composite films is limited by their lack of hydrophobicity and non-fouling properties, as well as their low corrosion resistance, affecting their long-term stability in specific environments, such as high humidity environment, rainwater erosion, corrosion from pollutants, and dust pollution. In this work, a composite film with both superhydrophobicity and a high TC was constructed by spraying a silicon carbide (SiC) and polyurethane (PU) coating modified by perfluorooctylmethoxysilane (PFTMS) onto the surface of BNNS-filled polymer composite films. The PFTMS coupling agent not only improved the dispersibility of SiC in PU and the combination of SiC with PU, but also reduced the surface free energy of the film. The optimal mass ratio of SiC to PU for the SiC/PU composite coating was 1.2:1, resulting in superhydrophobic properties with a contact angle (CA) of 168.6 ± 1.3° and a rolling angle (RA) of 2.8 ± 1.2°. Meanwhile, SiC with higher TC also allowed the BNNS-filled composite films to maintain a high TC (32.3 W/m K). The composite films exhibited excellent TC and self-cleaning ability, as well as improved mechanical and chemical stability of the surface, which provides a strategy for enhancing the environmental adaptability of BNNS composite films and broadening their application scenarios. Superhydrophobic SiC/PU-coated BNNS composite films with excellent anti-fouling properties and high thermal conductivity [ABSTRACT FROM AUTHOR]

Copyright of Nuclear Safety is the property of Nuclear & Radiation Safety Center and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The amount of biomass production each year is huge, and microwave-assisted pyrolysis of biomass to obtain biogas, bio-oil, and biochar is a promising method. In this study, silicon carbide (SiC) was selected as the microwave absorber, and the effects of microwave power (400, 450, 500, 550 and 600 W), reactor chamber volume (100, 150, 200, 250, and 300 W), and the mass ratio of SiC and corn straw (0, 0.25, 0.5, 0.75, and 1) on the heating performances of corn straw particles were investigated and presented in this study. When the microwave power increased from 400 to 600 W, the average heating rate of corn straw particles increased from 23.06 ℃ /min to 101.46 ℃ /min, and that of mixture particles of corn straw and SiC increased from 87.00 ℃ /min to 236.88 ℃/min. When the reactor chamber volume increased from 100 to 300 mL, the average heating rate of corn straw particles decreased from 38.21 ℃/min to 22.54 ℃/min, and that of mixture particles of corn straw and SiC decreased from 98.84 ℃/min to 76.01 ℃/min. When the mass ratio of SiC and corn straw increased from 0 to 1, the average heating rate of mixture particles of corn straw and SiC increased from 101.46 ℃/min to 236.88 ℃/min. Some formulae with R2 values ranged from 0.971 to 0.998 were proposed to determine the transient temperatures of corn straw particles and mixture particles of corn straw and SiC. [ABSTRACT FROM AUTHOR]

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 Fenton reaction is known for generating highly reactive hydroxyl radicals that are applied to accelerate the polishing removal rate of chemically inert SiC substrates. However, previous research primarily focuses on the polishing removal rate acceleration on the C surfaces of SiC substrates, and very limited studies have been conducted to investigate whether the hydroxyl radicals produced by the Fenton reaction serve as the primary agents of oxidative activity. Furthermore, the oxidation ability of hydroxyl radicals on the C surface and its relationship with their concentration are still not well-established. Therefore, more extensive research is needed to gain comprehensive understanding on the role of hydroxyl radicals in the oxidative activity on the C surface and their concentration-dependent effects. In this study, the polishing results of alumina, cerium oxide, and silica containing polishing slurries with and without Fenton reaction were compared and analyzed. The material removal rate (MRR) of the C surfaces of SiC substrates was significantly improved after the introduction of the Fenton reaction in alumina-containing slurry at pH 4, resulting in a smoother surface. Low-field nuclear magnetism, atomic force microscopy (AFM), ultraviolet spectrophotometry, and X-ray photoelectron spectroscopy (XPS) were employed to gain insights on inter-particle interactions and oxidation mechanisms of C face of SiC in presence of Fenton reaction. The results revealed that while hydroxyl radicals demonstrated potent oxidation ability, they alone were incapable of oxidizing C face of SiC. [ABSTRACT FROM AUTHOR]

To address the challenge of high-temperature microwave absorbing materials (MAM) for the hot-end components of aircraft, SiC enhanced ZrB 2 –Al 2 O 3 (ZSA) ceramics are prepared by pressureless sintering. In ZSA ceramics, ZrB 2 and SiC are the absorbers and Al 2 O 3 is the matrix. The effect of the content of SiC on microwave absorption properties for the ZSA ceramics are studied. The results show that the addition of SiC enhances the MA properties and high-temperature stability of ZrB 2 –Al 2 O 3 ceramics. Ceramics with an effective absorption bandwidth (EAB) of 3.9 GHz at a thickness of 1.56 mm; and a minimum reflection loss (RL min) of −15 dB is obtained. After treatment at 1000 °C for 20 h in an air atmosphere, the EAB reduces to 3.5 GHz at the thickness of 1.56 mm, however, RL min reaches −21 dB. ZSA ceramics consume microwaves through effect including interfacial polarization relaxation, conductive loss and multiple reflection loss. This work is expected to provide new ideas for the design and development of high-temperature microwave absorbing materials. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

New C/SiC composites with continuous fibers were produced through impregnation of carbon fiber preforms and consolidation by hot pressing. The resulting sintered material was investigated as a potential target for nuclear applications, such as radioisotope production. Desired properties include high porosity and high thermal conductivity to allow isotope release from the targets while working at high temperature. To this end, porosimetry and thermal and mechanical characterizations were conducted up to 1250°C. It was shown that the addition of fibers resulted in high porosity, about 40%, while maintaining a very high thermal conductivity, 40 W/m∙K at 1250°C, a value particularly attractive for the intended application. Emissivity at 1250°C was 0.76, compressive strength at room temperature was 134 MPa, and flexural strength passed from about 90 MPa before thermal conductivity measurements to 50 MPa after the tests. [ABSTRACT FROM AUTHOR]

Silicon carbide (SiC) is a multifunctional material with a myriad of potential applications, from high-power electronics to friction applications to power generation. Grafting preceramic polymers (PCPs) from SiC nanoparticles would create a platform for forming SiC via a polymer derived route that would have advantages over simple particle-PCP slurries and may enable new additive manufacturing inks or spreadable coatings with controlled rheology. Grafting PCPs directly on SiC powders would greatly improve dispersion of these particles and yield a single component system. Moreover, PCP-grafted-SiC would be a new addition to the burgeoning field of polymer grafted nanoparticles (PGNPs). Herein, SiC nanoparticles were surface-modified in a grafting-from polymerization reaction to create polycarbosilane (PCS) grafted SiC. Surface grafting was verified through a number of analytical techniques and the synthesized materials were pyrolyzed at 1600 °C. The PCS-grafted SiC retained 66 % of its pre-pyrolysis mass, representing a significant improvement over PCS-grafted silica nanoparticles from our previous work (20 wt% yield). In addition to an increased ceramic yield, the grafting of PCS to SiC also resulted in the formation of a SiC phase not present in the simple physical mixture of SiC nanopowder in PCS. This study demonstrated that PCP-grafted nanoparticles (GNPs) can be synthesized utilizing non-oxide nanoparticle cores with desirable rheology, opening possibilities for future ceramic inks and coatings. [ABSTRACT FROM AUTHOR]

The Ho-Bi-Te ternary system was studied by DTA, X-ray diffraction, and MSA, as well as by measuring microhardness and determining density, congruent triangulation scheme and projection of the liquidus surface, types and coordinates of mono- and invariant equilibria. It is established that this system is triangulated into five pseudo-ternary systems. It was discovered that an incongruently melting ternary compound containing HoBiTe3 is formed in the Ho-Bi-Te ternary system. X-ray phase analysis established that the HoBiTe3 compound crystallises in a tetragonal system with lattice parameters: a = 19.99, с = 13.82 Å, Z = 3. Studying the nature of the interaction of the components of the quasi-binary section Bi2Te3-Ho2Te3 of the Ho-Bi-Te ternary system, as well as thermoelectric materials formed by combining Bi2Te3 with rare-earth tellurides, is of interest from a scientific and practical point of view. [ABSTRACT FROM AUTHOR]

A comprehensive process model for 4H‐SiC oxidation is created and calibrated against a very large collection of experimental data. The model reproduces measured oxide thickness for Si‐face, C‐face, and a‐face SiC wafers, in the temperature range 950–1500 °C, in the pressure range 0.25–4.0 atm, in the thickness range 3–1600 nm, and for SiC doping ranging between 1019 cm−3 n‐type and 1019 cm−3 p‐type. The model is based on the Massoud model: Oxidation is driven by oxidants (O2, H2O) which are present in the gas phase, diffuse through the oxide, and form SiO2 at the oxide–SiC interface. For thin oxides, the interface reaction rate includes empirical correction terms which add to the oxidation rate, and which asymptotically approach zero with increasing oxide thickness. For dry oxidation, a remarkable dependence on the O2 partial pressure is discovered: For thick oxides, the oxidation rate scales linearly with the pressure, but the correction term for thin oxides scales with the square root of the pressure. This suggests that the atomistic processes responsible for the fast initial growth of oxides involve the splitting of O2 molecules into two O atoms. [ABSTRACT FROM AUTHOR]

The motto of research is to attempt to enrich the mechanical and fracture resistance quality of AA5052 alloy composite composed by the adaptations of 0, 3, 6, and 9 weight percentages (wt%) of silicon carbide (SiC) nanoparticle and 5 wt% of chopped E-glass fiber through vacuum-assisted stir processing under 500 rpm. The metallography analysis of composite samples is analyzed and spots the good interfacial with void-less structure. The composite's mechanical and fracture qualities enriched through the inclusion of SiC (9 wt%) / E-glass fiber (5 wt%) in AA5052 alloy composite attained the highest tensile strength, better hardness, improved elongation percentage and excellent fracture toughness, which is enhanced by 25.5, 33.8, 22, and 15 % comparable to the value of monolithic AA5052 alloy cast. The E-glass configured hybrid AA5052/SiC alloy composite is suggested for automotive body structural applications. [ABSTRACT FROM AUTHOR]

CVD-SiC and sintered SiC (SPS-SiC) were proton irradiated at 340 ̊C receiving different levels of damage (0.05–0.25 dpa). A novel multi-step machining and measurement method using laser flash analysis (LFA) was developed to derive the thermal conductivity of the irradiated layer (∼46 µm). Before irradiation, the thermal conductivity of SPS-SiC was much lower than CVD-SiC, primarily due to its higher intrinsic defect concentration and smaller grain size which provide a greater density of barriers to phonon transmission. Following irradiation, major thermal conductivity degradation (∼90%) was found to occur to both types of SiC after only a low dose (∼0.1 dpa), with both saturating at a similarly low value (a few W/K⋅m), as the thermal resistivity due to the presence of high density of grain boundaries became less important. Thermal conductivity degradation after irradiation was primarily caused by point defects in both types of SiC, as reflected by Raman spectra. [ABSTRACT FROM AUTHOR]

Friction stir welding (FSW) is a process that can join many materials by causing minimal internal stress without the need for a direct electric current, contrary to traditional welding methods. The effects of SiC and Al2O3 reinforcing powders on the joining of AA6061-T6 and AA7075-T6 plates, which are difficult to join with conventional welding methods by FSW, are investigated in this study. The metallurgical properties of the combined samples are examined in terms of strength characteristics to investigate the effects of the reinforcement powder. In addition, elemental analysis is carried out for the mixing behavior of the powders. Finally, we used the TOPSIS method to select the most appropriate powder types to improve welding quality. Furthermore, a game theory application is presented to determine which powder type is suitable considering the joined aluminum plate's strength expectations. [ABSTRACT FROM AUTHOR]

Measured electronic stopping powers along the 〈0001〉 direction (S e) of 4H-SiC and 2H-GaN for low-velocity 12Mg, 13Al, and 15P ions were reproduced with the modified El-Hoshy−Gibbons model that reduced not only the atomic numbers of projectiles and targets but also the impact parameter for small-angle collisions (based on the Kohn−Sham radii of projectiles) in the Firsov model. Unreported S e of 2H-GaN for low-velocity 14Si ions was then predicted to be between S e of 2H-GaN for 12Mg ions and S e of 4H-SiC for 13Al ions, indicating not only Al and Mg but also Si channeling being usable for fabricating cost-effective superjunctions. [ABSTRACT FROM AUTHOR]

The low thermal conductivity, the small magnitude of modulus of elasticity, and the high chemical reactivity of Ti-6Al-4V make it difficult to machine this material using traditional processes. The intended requirements for the applications of the said alloy, like in biomedical and aerospace, further complicate its processing. Thereof, electric discharge machining (EDM) opted for this alloy. However, intrinsic issues of EDM, that is, electrode wear rate (EWR) and dimensional overcuts, restricted its utilization. Therefore, the potential of three powder-based additives and dielectric fluids against different electrode materials has been deeply envisaged to address the abovementioned issues. Because the choice of best dielectric has a direct bearing on heat input to the electrode which influences the melting/vaporization of the tool wear of the electrode. It is worth mentioning that these concerns have not been discussed so far in such a broad spectrum. Taguchi's experimental design is used for experimentation. The results show that transformer oil performance is best rated compared to other dielectrics. Overall, the reduction in tool wear rate and overcut obtained with transformer oil is 21.3% and 21.4%, respectively, in contrast to the other dielectrics. The electrode of Cu outperforms for yielding the smaller value of overcut and tool wear rate. In the case of micro-additives, alumina has proved its potential for lowering the electrode wear rate. Deep and wide craters of a depth of 150 µm have been observed by using the brass electrode in kerosene oil, whereas the small and shallow craters of 38 µm depth have been encountered using the Cu electrode in the presence of transformer oil. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In the present work, aluminum alloy Al8090 was reinforced by 2 wt.% of SiC and various wt.% of B4C such as 2, 4 and 6 to develop Al8090/SiC/B4C hybrid metal matrix composites (HMMCs) using double step stir casting technique. Metallurgical characterization, physical properties, mechanical properties and thermal behavior were determined on the samples prepared from the developed hybrid composites. EDAX analysis was performed on the hybrid composite having maximum and minimum reinforcement particles. The presence of matrix material and reinforcement particles were analyzed and defect-free castings were confirmed. [ABSTRACT FROM AUTHOR]

The development of lightweight and high-strength materials is critical for many industries, including aerospace, automotive, and electronics. Metal matrix composites (MMCs) have shown great promise in meeting these requirements. The structural and physical properties of Al6061 alloy reinforced with hybrid MMCs, including TiB2, SiC, and fly ash (FA), were investigated in this research review. The MMCs investigated were made using the stir-casting process. Their microstructure, structural characteristics, and mechanical features were examined. The inclusion of TiB2 and SiC enhanced the composite’s hardness, tensile strength, and wear resistance, while the addition of FA lowered its density and improved its thermal and corrosion resistance. However, the volume percentage, particle dimension, and arrangement of the reinforcing components all had an effect on the physical characteristics of the composite. Therefore, the optimum combination of the reinforcing materials must be carefully selected to achieve the desired properties. The result of this review provides valuable insights into the development of high-performance MMCs for various industrial applications. [ABSTRACT FROM AUTHOR]