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Silicon carbide (SiC) has excellent characteristics such as strong high-temperature oxidation resistance, good wear resistance, and high hardness ・ After the surface of SiC particles was treated with silane coupling agent, in・situ polymerization grafting of polymethyl methacrylate(PMMA) chains was carried out for composite and functionalization, resulting in PMMA/SiC composite particles. The effect of PMMA/SiC composite particles on the friction performance of regenerated lubricating oil was studied・ The results showed that the hydrophilicity and dispersibility of PMMA/SiC composite particles in oil were significantly improved, and the best anti friction effect was observed when the addition amount in regenerated lubricating oil was 0. 25%, which could reduce the friction coefficient of regenerated lubricating oil from 0・ 16 to 0. 05, a decrease of 68・9%・ PMMA/SiC composite particles added to regenerated lubricating oil deposit and fill the grooves and scratches on the worn surface during the wear process, playing a role in polishing and ball bearing・ In friction and wear experiments under different working conditions, it can effectively cover the surface of the friction pair, reduce the friction coefficient, and make the friction pair have anti heavy load performance. [ABSTRACT FROM AUTHOR]

Silicon carbide (SiC) is one of the superior materials used in the manufacture of electronic components designed to work at high temperatures, high frequencies and high-power. In the past two decades, the application of SiC materials has been expanding as a result of much improved production and processing techniques. Although most SiC chips are still mainly made from 6 inch (1 inch =25. 4 mm) wafers, leading manufacturers have begun developing next-generation parts and chips based upon 8 inch SiC wafers. This study collaborates with leading enterprises in the upstream and downstream of the domestic silicon carbide industry chain in order to facilitate domestic production of 8 inch SiC chips, with the focus being wafer preparation and epitaxial growth. In this work, 8 inch conductive 4H-SiC substrate wafer was prepared by diameter expansion growth, with low average base plane dislocation (BPD) density (251 cm-2) and virtually 'zero threading screw dislocation (TSD)' density (< 1 cm-2) that meet the production requirements. Based on these 8 inch substrates, we achieve fast epitaxial growth (68. 66 μm/h) with domestically produced 8 inch epitaxy equipment and processing packages. The thickness uniformity of the resultant wafers is 0. 89% and the doping uniformity is 2. 05%. These parameters, as well as the defect density, are on par with those of high-quality 6-inch wafers, fully meeting production requirements. The 8 inch wafers prepared in this paper are better than those described in international publications in terms of thickness and doping uniformity. The defect density is only 1/4 of international data. In this paper, multi-wafer repetative text was designed and executed, to verify the stability of 8 inch epitaxy. [ABSTRACT FROM AUTHOR]

Copyright of Rolling Stock (1002-7602) is the property of Rolling Stock Editorial Office 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.)

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office 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.)

Graphene/SiCp/PCS slurry was obtained by adding graphene/SiCp composite powder into polycarbosilane (PCS) solution of silicon carbide precursor. Graphene/SiCp/SiC composites were prepared by direct ink writing 3D printing (DIW) and high temperature sintering. PCS has different products and properties at different pyrolysis temperatures. In this paper, the effect of pyrolysis temperature on the properties of graphene/SiCp/SiC composites was studied. PCS is converted into amorphous SiCxOy at 800 °C. As the temperature increases to 1500 °C, β-SiC and free carbon with higher conductivity were gradually formed from the amorphous SiCxOy. The conductivity of graphene/SiCp/SiC composites increases from 0.93 S⋅m-1 to 670 S⋅m-1. At 1200 °C, the compressive strength and bulk density of the composites reached the maximum of 12.3 MPa and 1.49 g⋅cm-3, respectively. This study provides a method to prepare highly conductive lightweight porous graphene/SiCp/SiC composite ceramics by direct writing 3D printing process based on PCS slurry. [ABSTRACT FROM AUTHOR]

Copyright of Refractories / Naihuo Cailiao is the property of Naihuo Cailia (Refractories) Editorial Office 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.)

Copyright of Refractories / Naihuo Cailiao is the property of Naihuo Cailia (Refractories) Editorial Office 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.)

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING 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.)

Nanofluids based on seawater can be used as hydraulic medium in marine hydraulic equipment to solve the problem of fluid deterioration caused by seawater intrusion in traditional hydraulic fluids. In this paper, seawater-based SiC nanofluids were prepared by a two-step method using natural seawater as the base fluid, and the dispersion stability and viscosity characteristics of nanofluids with different group distribution ratios were investigated by the single-variable method. The results showed that NaCl destroyed the particle double electric layer and reduced the nanofluid stabilization coefficient, but the surfactant CMC could be adsorbed on the surface of SiC particles to provide spatial site resistance, so that the stabilization coefficient was maintained at about 0.9 within 10 days. Meanwhile, it was verified that the best nanofluid dispersion stability was achieved with SiC particle size at 40 nm, mass fraction at around 1%, and CMC mass fraction at around 2%. The viscosity of seawater-based nanofluid increased with the increase of particle addition, and the rising trend slowed down when the mass fraction was greater than 1%. With the increase of CMC addition, the microstructure in the nanofluid was affected, so that the viscosity of the seawater-based nanofluid increased with the increase of the CMC mass fraction, and the rising trend was smooth-sharp-smooth. The viscosity was negatively correlated to the temperature by the effect of Brownian motion, and the viscosity of the nanofluid decreased with the increase of NaCl mass fraction, and the decreasing trend was fast and then slow. The seawater-based nanofluids prepared in this paper have good dispersion stability, and the desired viscosity can be obtained by regulating the group distribution ratio, which is helpful for the further development of nanofluid technology. [ABSTRACT FROM AUTHOR]

As the international situation continues to change and conflicts in various countries intensify, improving national defense forces is a necessary condition to ensure the stable development of the country, and bulletproof armor is a key part of it. Pressureless sintered silicon carbide ceramics have been widely used in the field of bulletproof armor because of its simple preparation process and excellent mechanical properties of low density, high hardness and high strength. The hardness and fracture toughness of pressureless sintered silicon carbide bulletproof ceramics directly determine the quality of bulletproof performance. Promoting sintering densification and multi-phase composite sintering are the key ways to improve the hardness and fracture toughness of pressureless sintered silicon carbide ceramics. This sturdy summarizes the research progress of pressureless sintered silicon carbide bulletproof ceramic materials in recent years, focusing on the sintering aids, toughening methods, composite form of pressureless sintered silicon carbide bulletproof ceramic materials. [ABSTRACT FROM AUTHOR]

Copyright of Plastics Science & Technology / Suliao Ke-Ji is the property of Plastics Science & Technology Editorial Office 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.)

Copyright of Journal of Railway Science & Engineering is the property of Journal of Railway Science & Engineering Editorial Office 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.)

Copyright of Refractories / Naihuo Cailiao is the property of Naihuo Cailia (Refractories) Editorial Office 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.)

Copyright of Refractories / Naihuo Cailiao is the property of Naihuo Cailia (Refractories) Editorial Office 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.)

Copyright of Refractories / Naihuo Cailiao is the property of Naihuo Cailia (Refractories) Editorial Office 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.)

Copyright of Refractories / Naihuo Cailiao is the property of Naihuo Cailia (Refractories) Editorial Office 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.)

Silicon carbide (SiC) is an important material for shielding nuclear fission products in tri-structural isotropic (TRISO) particles for high-temperature gas-cooled reactors. It has an important influence on the safety performance of TRISO particles. Therefore, it is necessary to study the irradiation behaviors and mechanical properties of the SiC layer of TRISO particles. The irradiation process and nanoindentation process can be described accurately by molecular dynamics simulations. It is helpful to analyze the irradiation behavior and mechanical properties of materials. In this paper, molecular dynamics simulations were used to study the irradiation behavior of equiaxed polycrystalline and long-axis polycrystalline SiC layers obtained from experiments. The calculated theoretical values of the irradiation swelling degree and mechanical properties of the SiC layer are in good agreement with the experimental values. It shows the strong applicability of the potential functions and other simulation system parameters used in this paper. The irradiation behavior of the SiC layer was studied in detail by swelling degree, density, atomic structure type, and point defect evolution. The results show that the grain structure of the SiC layer has no significant effect on its irradiation swelling and amorphization. The amorphization is not directly converted from the crystal structure to the amorphous structure during the irradiation process. The crystal structure is converted into an intermediate state structure and then converted into an amorphous structure. The point defects are mainly C vacancies, Si interstitial atoms, and C antisite atoms in the early stage of irradiation. The difference between the ratio of C point defects and Si point defects gradually disappears after the irradiation dose tends to be saturated. The evolution of amorphization and point defects tends to start nearby the grain boundaries. Irradiation reduces the mechanical properties of SiC layers. It no longer has a significant effect on the mechanical properties of the SiC layer after the irradiation dose tends to be saturated. The changes in the mechanical properties of the SiC layer before and after irradiation were analyzed by load-depth curve and stress & strain. The results show that the decrease in mechanical properties of the SiC layer is closely related to the mechanical behaviors under external force. For example, the bearing capacity and plastic deformation degree decrease, and the stress & strain distribution are disordered. The results provide a quantitative explanation for the irradiation behavior of the SiC layer of TRISO particles and the change of mechanical properties under irradiation. It is helpful to understand the irradiation behavior and relationship between the irradiation behavior and mechanical properties of the SiC layer.

In order to reveal the damage evolution and failure mechanism of ceramic matrix composites (CMCs), in-situ X-ray CT compression tests of plain weave SiCf/SiC composites were conducted, and the CT data during loading and after failure were obtained. Displacement and strain distributions of the material were evaluated by the digital volume correlation (DVC) technology. The three-dimensional visual model of the composite was created by using image processing software. The spatial distributions of tow split and other damages were segmented by the deep learning algorithm. The qualitative and quantitative analysis of compression damage evolution were performed. The results show that there is a relatively large expansion induced by barreling in the thickness direction and a little shrinkage in the width direction during the unidirectional compression, while the barreling in the thickness direction is the main reason to trigger compressive damages of the material. Damages such as matrix falling-off at surface, tow split, delamination, will occur as the compression was approaching the ultimate load. Fiber kinking results in the final compressive failure of the material, while an obvious V-shaped shear band is observed in the fracture. The analysis of compressive damage evolution of plain weave SiCf/SiC shows that the DVC technology and deep learning-based image segmentation methods could effectively reveal the compressive damage evolution mechanism of ceramic matrix composites.

To address issues related to abrasion, agglomeration, and the challenges of mechanical and chemical release during chemical mechanical polishing (CMP), a vibration-assisted CMP method is employed. Molecular dynamics simulation analyze the dynamic evolution of frequency, amplitude, and indentation depth, along with the dicing speed of abrasive vibration on the workpiece's surface. It reveals the mechanism behind enhanced material removal and improved surface quality facilitated by vibration. The effectiveness and removal mechanism of vibration-assisted CMP are validated through process testing and surface composition analysis. The results show that atomic potential energy and temperature on the workpiece surface can be effectively improved by appropriately increasing vibration frequency, vibration amplitude, indentation depth, and abrasive particle cutting speed. Abrasive vibration contributes to increased atomic disorder on the workpiece surface, facilitating the participation of silicon carbide in oxidation reactions. This process results in the formation of an oxide layer, which is mechanically removed. Polishing tests and composition analyses also confirms that vibration can improve material removal rates by about 50.5% and improve the surface quality by about 25.4%.

Polycarbosilane was used to prepare modifed silicon carbide powder by coating method, this polycarbosilane-coated powder was used to prepare a green body of the membrane layer and sintered into a silicon carbide ceramic membrane with good morphology. The morphology and rejection performance of the membrane were analyzed by means of scanning electron microscope, laser confocal microscope, mercury intrusion porosimeter and rejection performance test. The results showed that polycarbosilane played the role of sintering binder in the sintering process. When the coating amount was 5%, the surface of the layer was smooth without cracks, and the layer shape was good. When the silicon carbide particle size was 0. 3 μm, the polycarbosilane coating amount was 5% and the sintering temperature was 1 750 ℃, the pore size of the prepared membrane layer was 0. 842 μm, and the rejection rate of 100 nm nanospheres was as high as 89%. This study has shown that polycarbosilane has obvious advantages in the application of silicon carbide membrane morphology and pore size control. [ABSTRACT FROM AUTHOR]

Chemical mechanical polishing (CMP) has become a critical process step in semiconductor manufacturing. This technique is a commonly used and effective method for achieving ultra-precision processing of silicon carbide wafers, playing a key role in the fabrication of semiconductor devices. CMP is employed to process the wafer surface, resulting in high material removal rates, excellent surface quality, and superior surface planarity of the chips. However, in the CMP of silicon carbide (SiC) wafers, the non-uniformity of material removal on the chip surface has been a challenging issue. Reducing the nonuniformity of material removal is essential for ensuring the high performance and stability of semiconductor devices. This article introduces the properties and applications of silicon carbide, along with the CMP process. It investigates the material removal mechanisms of different CMP techniques for silicon carbide, explores the development status of various CMP technologies, and evaluates the performance and pros and cons of different CMP techniques. The article provides an overview of the factors influencing material removal non-uniformity in CMP of silicon carbide wafers, including factors such as polishing pressure, polishing slurry (abrasives), and rotation speed. Finally, the article provides prospects for future research on material removal non-uniformity in silicon carbide CMP. [ABSTRACT FROM AUTHOR]

Copyright of China Synthetic Fiber Industry is the property of Sinopec Baling Petrochemical Company 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.)

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology 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.)

In order to improve the filtration performance, silicon carbide porous ceramics with network cell wall were fabricated via the polyurethane foaming method using silicon carbide powder, alumina powder, polyether polyol, polymethylene polyphenyl polyisocyanate, dibutyltin dilaurate, triethylenediamine and silicone oil (foam stabilizer) as raw materials. The effects of the solid loadings of the slurry (45%, 50%, 55% and 60%, by mass) on the microstructure, physical properties and their filtration properties towards particu-late matters were studied. The result shows that: (1) with the increasing solid loading, the bulk density and cold compressive strength gradually increase, and the apparent porosity decreases; (2) the micropores generated during the polyurethane foaming process are distributed on the ceramic pore wall to form a network cell wall structure, which increases the collision probability between particles and the wall pores and improves the filtration efficiency; meanwhile, the network cell wall structure also improves the pore interconnectivity and reduces the press drop; (3) when the solid loading is 55%, the silicon carbide based porous ceramics have the bulk density of 0.57 g · cm-3, apparent porosity of 79.2%, cold compressive strength of 3.7 MPa, and the filtering efficiency of the paniculate matter of 91.2%, achieving good regeneration performance. [ABSTRACT FROM AUTHOR]

Copyright of Electric Drive is the property of Electric Drive Editorial Office 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 performance and lifetime of silicon carbide (SiC) devices are directly affected by the quality of SiC epitaxial films. On the one hand, the quality of SiC epitaxial films is affected by the quality of substrates. For examples, the stacking faults (SF) in substrates penetrate into the epitaxial layer, forming bar-shaped stacking faults (BSF), and the threading screw dislocation (TSD) penetrate into the epitaxial layer to form pits or Frank-type stacking faults (Frank SF). On the other hand, the quality of SiC epitaxial films is also influenced by the epitaxial growing process. For examples, basal plane dislocation (BPD) in the substrate form Σ-basal plane dislocation (Σ-BPD) in the epitaxial layer under thermal stress or other unstable conditions, the TSD and threading edge dislocation (TED) in the substrate may be etched and derived into pits, and SF and silicon droplets may also be produced. Therefore, high quality SiC substrates and optimized epitaxial growing process are both crucial for obtaining high-quality silicon carbide epitaxial wafers. In this article, based on the SiC epitaxial films grown on 6 inch SiC substrates batch-produced by TankeBlue Company, the defects reproducing process in substrates during epitaxial growing were analyzed, and the formation mechanism and controlling technology of common defects such as BPD, SF, silicon droplets and pits were overviewed. The generation mechanism of Σ-BPD and its eliminating methods were also explored. Finally, we obtained the mass-production technologies of SiC epitaxial films with good thickness and concentration uniformity, and low defect density, which are qualified for making 650 and 1 200 V SiC-based MOSFETs. [ABSTRACT FROM AUTHOR]

Semiconducting silicon carbide (4H-SiC) exhibits characteristics of high hardness, notable brittleness, and excellent chemical stability. The commonly employed technique for achieving an ultra-smooth and flat surface is chemical mechanical polishing (CMP), which is utilized to process the 4H-SiC surface. Wet oxidation, as an important process of chemical-mechanical polishing of single-crystal 4H-SiC, directly affects the rate and surface quality of CMP. This paper provides a comprehensive overview of the current research status of wet oxidation of single-crystal 4H-SiC. It discusses the oxidants used in the wet oxidation of 4H-SiC, such as KMnO4, H2O2, K2S2O8. Based on this, it further summarizes commonly employed oxidation-enhancement methods, including photocatalytic-assisted oxidation, electrochemical oxidation, and Fenton reaction. The mechanism of wet oxidation of single-crystal 4H-SiC is analyzed from the aspect of theoretical calculation, and the future research direction of wet oxidation of 4H-SiC is proposed. [ABSTRACT FROM AUTHOR]

Copyright of Diamond & Abrasives Engineering is the property of Zhengzhou Research Institute for Abrasives & Grinding 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.)

Copyright of Journal of Shanghai Jiao Tong University (1006-2467) is the property of Journal of Shanghai Jiao Tong University Editorial Office 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.)

Copyright of Refractories / Naihuo Cailiao is the property of Naihuo Cailia (Refractories) Editorial Office 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.)

As one kind of advanced high temperature structural and functional materials, it is necessary for fiber reinforced silicon carbide matrix composites (SiC CMCs) in the field of thermal management (TM) to combine the efficient heat transfer and high temperature heat resistance. Common fibers reinforced SiC CMCs, such as carbon fibers reinforced SiC CMCs (Cf/SiC or Cf/C-SiC), silicon carbide based fiber reinforced SiC CMCs (SiCf/SiC), etc., have a low degree of graphitization of the reinforcing fiber and are difficult to form an effective heat transport network. The latest research progress on the preparation and properties of fiber reinforced SiC CMCs with highly thermal conductivity was reviewed in this paper. The heat transport ability of fiber reinforced SiC CMCs can be improved by introducing highly thermal conductive phase, optimizing interfacial structure, making silicon carbide crystal coarse-grained, and designing preform structure. Moreover, the development of the fiber reinforced SiC CMCs with highly thermal conductivities was prospected, that is, comprehensively considering the factors that affect the performance of SiC CMCs, flexibly using the structure-activity relationship between the microstructure and properties of the composites, in order to prepare fiber reinforced SiC CMCs with stable size, excellent properties.

SiC is the ideal material for RF devices and power devices. Resistance-heated physical vapor transport method is considered a promising way to grow large size (especially 6 and 8 inch) SiC crystals due to its temperature uniformity. In recent years, the introduction of new technique such as the use of porous graphite improved the SiC crystal quality and yield, while there are only a few relatively comprehensive studies on its mechanism. This paper made comprehensive research on the influence of porous graphite on SiC growth system by means of numerical simulation. The crystal growth experiments under numerical simulation conditions have been carried out accordingly. The numerical simulation results show that the porous graphite raises the temperature and temperature uniformity within the powder area, which can strengthen the sublimation of powder. The temperature difference between the powder and the seed inside the crucible is improved and a greater growth driving force is obtained. The effect of decrease of the re-crystallization at powder surface has also been proved. Besides, the porous graphite improves the flow stability across the whole growth process, and assures a stable crystal growth. The C/ Si ratio has been increased under the influence of porous graphite, and thus reduces the probability of phase transition. The crystal shape has also been improved. The subsequent growth experiments verified the conclusions of numerical simulations such as the improvement of flow uniformity, decrease of poly-type transition probability, improvement of crystal shape, etc. The results of this paper have practical significance on comprehending the effecting mechanism of porous graphite and improving the SiC crystal growth conditions for better crystal quality. [ABSTRACT FROM AUTHOR]

In order to optimize and analyze the heat transfer and flow performance of Z-shaped silicon carbide printed circuit heat exchanger(PCHE) as a high temperature regenerator, the method of combining numerical simulation and response surface methodology is used to optimize the design with the Nusselt number and Fanning friction coefficient as the response, and the cold fluid pressure, cold fluid inlet temperature, hot fluid inlet temperature, channel bending angle, channel diameter and mass flow rate as the influence factors to determine the optimal structure and process parameters. The results show that the channel bending angle has the highest significance to the Fanning friction coefficient on the response hot side, and the channel diameter has the highest significance to the Nusselt number on the response hot side. It is concluded that when the Z-shaped silicon carbide PCHE is used as a high temperature regenerator, the cold fluid pressure is 30 MPa, the cold fluid inlet temperature is 568.44 K, the hot fluid inlet temperature is 893.813 K, the channel bending angle is 15°, the diameter is 1.769 mm, and the mass flow rate is 349.997 kg/(m² ⋅ s), the flow resistance is the smallest. When the cold fluid pressure is 23.078 MPa, the cold fluid inlet temperature is 541.961 K, the hot fluid inlet temperature is 800.045 K, the channel bending angle is 45°, the diameter is 1.8 mm, the mass flow rate is 350 kg/(m m² ⋅ s), the heat transfer effect is the best. [ABSTRACT FROM AUTHOR]

The quantum precision magnetic measurement in high-pressure environments is of great significance for studying the evolution and structure of matter under an extreme environment. Given the challenges associated with achieving in-situ high-resolution magnetic detection under high pressure by using traditional methods, the proposed high-pressure quantum magnetic measurement based on solid-state color centres has made significant progress in recent years. This advancement is of great significance in advancing the study of matter under high pressure. And this paper primarily focuses on the research of quantum magnetic measurement using SiC color centres under high pressure. The optical and spin properties of silicon vacancy defects and divacancy defects in SiC under high pressure is reviewed. Furthermore, the magnetic phase transition of Nd2Fe14B is observed, and the critical temperature-pressure phase diagram of the superconductor YBa2Cu3O6.6 is mapped out. This work reviews and highlights the potential of silicon vacancy-based quantum sensors for in situ magnetic detection at high pressures. Its applications in pressure sensing, pressure-induced magnetic phase transformation and pressure-induced superconducting transformation are also presented. [ABSTRACT FROM AUTHOR]

4H silicon carbide (4H-SiC) substrate wafers without surface / subsurface damages and low surface roughness are ideal substrates for the development of power electronics and radio frequency (RF) microwave devices, which hold great promise in applications of new energy, rail transportation, smart grid and 5G communication. The processing of 4H-SiC substrate wafers includes slicing, grinding, lapping, polishing and cleaning. However, the surface damages ( SDs) and subsurface damages (SSDs) introduced during the processing of 4H-SiC substrates affects the properties of 4H-SiC substrates and epitaxial layers, and thus the performance and reliability of devices based on 4H-SiC. This paper focuses on the formation and removal mechanisms of SDs / SSDs during the processing of 4H-SiC substrate wafers. Based on the detection method of SDs / SSDs, the morphologies and characterization approaches of SDs / SSDs are reviewed. Finally, three commonly used technologies for the removal SDs / SSDs, along with their technical advantages, development challenges and trends, are briefly discussed. [ABSTRACT FROM AUTHOR]

As for the severe working conditions of piston rod such as high temperature, high pressure, and fast movement, Ni--SiC composite electroplating was conducted on the surface of piston rod to improve its wear and corrosion resistance. The effects of particle size and pretreatment method of SiC powder on the surface roughness, micromorphology, and SiC content of composite coating were studied. The results showed that all the Ni--SiC composite coatings featured good appearance, uniform microstructure with well-distributed SiC particles, and strong adhesion to the 45 steel substrate without any gaps. The content of SiC in composite coating was increased slowly initially, then quickly, and slowly finally with the increasing of particle size from 2 to 10 µm for the SiC powder pretreated by the same method. For the same particle size of SiC, the content of SiC powder pretreated with different chemicals in composite coating was in the following descending order: sodium dodecyl sulfonate (a surfactant), anhydrous ethanol, and hydrochloric acid. [ABSTRACT FROM AUTHOR]

In the context of rapid social development, it is urgent to address the increasingly prominent issues of fossil energy depletion and environmental pollution. As a result, research has focused on the creation of new clean energy sources such as solar, wind, biological, geothermal, and hydrogen. Hydrogen energy is one of these new energy sources that has drawn a lot of attention because of its low weight, good thermal conductivity, high heating value, rich utilization forms, and diverse storage states. Nowadays, one of the most significant methods for producing clean energy is photoelectrochemical (PEC) water splitting for hydrogen. However, the intrinsic drawbacks of commonly used semiconductors, such as the low light absorption efficiency, high carrier recombination rate, and slow oxygen evolution kinetics, have become the main barriers preventing their advancement in PEC water splitting. This study used anodic oxidation to create N-doped 4H-SiC nanowire arrays (NWAs) from N-doped 4H-SiC single crystalline wafers. It can be verified that the highly oriented N-doped 4H-SiC NWAs are fully exposed by removing the cap layer. Additionally, the single bamboo-shaped nanowire that was produced has a diameter of ~30–50 nm. Focusing on the optimization of the oxygen evolution reaction (OER) conditions, the NWAs were used as an integrated photoanode in a typical three-electrode system to achieve effective PEC water splitting for hydrogen production under illumination and electric field. Notably, the N-doped 4H-SiC NWAs show better water splitting performance compared with the bulk; that is, the onset potential is decreased from 1.224 V to −0.021 V versus the Ag/AgCl electrode, and the current density is increased from 2.64 mA∙cm−2 to 3.61 mA∙cm−2 at 1.4 V. Particularly, the N-doped 4H-SiC NWAs exhibit an extremely sensitive response to light. The improved optical absorption capacity and efficient charge transfer of N-doped 4H-SiC NWAs are responsible for the improvement in PEC water splitting performance. On the one hand, when the N-doped 4H-SiC NWAs are exposed to light, a significant amount of light shines into the gap between the nanowires. N-doped 4H-SiC obtains additional light absorption pathways with the constant reflection of the light, significantly enhancing the light absorption efficiency. On the other hand, the NWAs can considerably reduce the hole travel distance and avoid the recombination of the photogenerated electron-hole pairs, making more charges participate in the redox reaction to enhance the PEC water splitting performance of N-doped 4H-SiC. By building semiconductor photoanode nanostructures, it is possible to efficiently absorb light and transfer charge, significantly enhancing the PEC water splitting efficiency.

This is a paper in the field of mineral synthesis, covering the areas of mineral processing engineering and ceramics and composites. Tailings of a vanadium-titanium magnetite plant in Panzhihua were subjected to regrinding and re-election experiments, and an iron ore concentrate with a Fe grade of 58.59% was obtained by the "step grinding and step separation" process. The ilmenite concentrate with TiO2 grade of 46.63% was obtained by adopting the flotation flowsheet of "one roughing, one scavenging, three cleaning". The TFe and TiO2 of the reselection tailings of vanadium-titanium magnetite were 5.71% and 2.96%, respectively. The process was achieved efficient separation of effective components. The foamed ceramic material with a volume density of 482 kg/m3 and a water absorption rate of 2.35%, and a compressive strength of 3.03 MPa was obtained by using the reselection tailings of vanadium-titanium magnetite, feldspar tailings and kaolinite pyrite tailings as the base material, and silicon carbide as blowing agent at 1160℃ for 30 min. The comprehensive utilization of vanadium-titanium magnetite tailings is realized.

The hardness of hard-brittle materials is high, which results in the low lapping efficiency of traditional silicon carbide magnetic abrasive and short abrasive life. In view of this situation, a magnetic abrasive with diamond particle as lapping grit was developed. Using high purity iron powder as iron-based phase and diamond particle as abrasive, diamond magnetic abrasives were prepared by resin bonding method. K9 glass was chosen as the part being machined. The service life and processing efficiency of magnetic lapping K9 glass were compared between with diamond magnetic abrasives and with silicon carbide magnetic abrasives. The lifespan of diamond magnetic abrasive is 60.00 min, and the number of work-piece which can be machined is 4.6 pieces in the service life. The average surface roughness of K9 glass reaches 0.036 μm. However, the service life of the silicon carbide magnetic abrasive particles is only 40 min, and the average surface roughness of the K9 glass workpiece can only be processed to 0.222 μm. Besides, the number of workpieces that can be processed during the service life is 3.6 pieces. Diamond magnetic abrasives can effectively improve the service life, the processing capacity of magnetic abrasives, and the processing efficiency of magnetic grinding.

In order to investigate the effects of co-deposition of SiC and WS2 particles on the microstructure, wear resistance and corrosion resistance of Ni coatings, the pure Ni coating, the Ni-SiC composite coating and Ni-SiC-WS2 composite coating were prepared on the surface of 1060 aluminum. Scanning electron microscopy (SEM), X-ray diffractometer (XRD), energy dispersive spectroscopy (EDS) and microhardness tester, friction and ball disc wear tester and electrochemical workstation were used to detect and analyze the surface and cross section morphology, phase composition, elemental contents and microhardness of the coatings, and the wear resistance and corrosion resistance of the pure Ni, Ni-SiC and Ni-SiC-WS2 composite coatings were compared. Results showed that the Ni-SiC-WS2 composite coating was flat and compact, with a mass fraction of 7.05% (mass fraction, the same below) and 2.53% for SiC and WS2, respectively. This resulted in the reduction of nickel grain size by 63.39% and 21.63%, compared with the pure Ni coating and the Ni-SiC composite coating, respectively. The microhardness of Ni-SiC-WS2 composite coating was up to 424.73 HV0.5 N, which was 57.70% and 20.46% higher than that of the pure Ni coating and the Ni-SiC composite coating, respectively. WS2 particles in the coating had good antifriction effect, which made the friction coefficient of the Ni-SiC-WS2 composite coating further reduced by 17.39% compared to Ni-SiC composite coating, and wear rate reduced by 24.62%. The self-corrosion current density of Ni-SiC-WS2 composite coating was the lowest, at 4.68 μA/cm2, which was reduced by 53.85% and 11.36%, compared with the pure Ni coating and the Ni-SiC composite coating, respectively. The Ni-SiC-WS2 composite coating had higher impedance value of 112 361 Ω·cm2, which demonstrated better corrosion resistance than the Ni coating and the Ni-SiC composite coating.

Recent new technologies and progress of refractories for iron and steel industry were introduced, including composite bonded silicon carbide materials for coke dry quenching furnaces, key refractories for hydrogen-based shaft furnaces, key refractories for OY furnaces (improved COREX-C3000), silicon carbide tuyere combination bricks for iron-making blast furnaces, environmentally friendly long-life Al2O3-SiC-C castables for blast furnace iron trough, zirconia slide plates for slag skimming of converters, refractories for refining ladles, gradient functional refractories for continuous casting, high-efficiency thermal insulation materials for high-temperature devices, recycling of hot blast furnace slag and foam ceramic filters for casting. Through the adoption of these new technologies, the requirements of new equipment and new technology in iron and steel industry can be met, improving the service life of existing furnace lining or key refractory materials, saving energy and decreasing consumption, purifying molten steel or molten iron, and strengthening the utilization of solid waste. [ABSTRACT FROM AUTHOR]

In order to study the effect of industrial carbon black on properties of multiphase bonded silicon carbide refractories,the samples were prepared using silicon carbide particles (3-1 and 1 - 0.088 mm) and fine powder ( <0.088 mm),silicon powder ( <0.088 mm),industrial carbon black (N990), microsilica (d50 =0.26 µm) and p-Al2O3 micropowder (d50 =6.0 µm) as the main raw materials, casting molding and heat treating at 1 400 °C in nitrogen atmosphere. The physical properties, phase composition and microstructure of samples with N990 additions of 2.5%, 3.0%, and 3.5% by mass were analyzed and compared.The results show that: (1) with N990 addition increasing, the flowability of the casting mud is improved, the demoulding and drying strengths are increased; (2) with the increase of N990 addition, the apparent porosity of the nitridized material increases, the bulk density and modulus of rupture both decrease, the content of free carbon increases, and the a-Si3N4 content decreases; (3) with the increase of N990 addition, because the particles agglomerating probability of carbon black increases, the uniformity of the samples become worse after nitridizing. Reaction sintering occurs between Si-C and Si-N, in addition to the continuous flocculent matrix, dense island-like β-SiC or O'-SiAlON phases also appear locally. It is thought after comprehensive analysis that the sample with 3.0% carbon black addition can better meet the need of material preparation and properties. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department 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.)

Copyright of Journal of Materials Engineering / Cailiao Gongcheng is the property of Journal of Materials Engineering Editorial Office 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.)

SiC ceramics were sintered with Al2O3-Y2O3-CaO as additives. The effects of sintering temperature and additives content on the relative density, polytype, microstructure and mechanical properties of SiC ceramics were investigated by Archimedes drainage method, XRD, SEM, TEM and Vickers hardness test. The results show that the relative density, hardness and fracture toughness of SiC ceramics increase firstly and then decrease from 1300 ℃ to 1800 ℃, and reach the maximum at 1700 ℃. The phase transformation from β-SiC to α-SiC occurs between 1700 ℃ and 1800 ℃. Reducing the content of additives can increase the grain boundary bonding strength, and can improve the hardness and inhibition of the grain growth. Under the condition of 1700 ℃ and 7% (mass fraction) additives content, the best sintering results are obtained, with relative density, hardness and toughness of 97.9%, 23.3 GPa and 4.1 MPa·m1/2, respectively.

BACKGROUND: The polishing treatment on the surface of the crown restoration can effectively reduce pigmentation, adhesion of plaque and abrasion of the jaw teeth. OBJECTIVE: To investigate the effects of different polishing treatments on the surface roughness and bacterial adhesion of the full zirconia restoration. METHODS: Totally 30 full zirconia specimens with sizes of 10 mm × 10 mm × 2 mm were prepared and divided into 5 groups randomly (n=6): control group (simple glazing treatment), polishing group (green silicon carbide sandstone, Shofu porcelain polishing kit, Ceramaster Polisher polishing), polishing paste group (green silicon carbide sandstone, Softcut PA, Shofu porcelain polishing kit, UltraII emery polishing paste), fine polishing group (green silicon carbide sandstone, Softcut PA, Shofu porcelain polishing kit, Ceramaster Polisher polishing), multi-step fine polishing group (green silicon carbide sandstone + white alumina sandstone, Softcut PA + Softcut PB, Shofu porcelain polishing kit, Ceramaster Polisher polishing). The surface roughness value, surface morphology of each specimens, and colony forming unit of bacteria on the surface of the specimens were detected after treatment. RESULTS AND CONCLUSION: (1) The surface roughness values of specimens of the five groups from high to low were: polishing group, polishing paste group, multi-step fine polishing group, fine polishing group, control group. The value was higher in the polishing group than that in other four groups (P < 0.05). The value was higher in the polishing paste group than that in the control group, fine polishing group, and multi-step fine polishing group (P < 0.05). (2) Under the electron microscope, the specimens of control group, fine polishing group and multi-step fine polishing group had smooth surface without visible scratches. The specimens of polishing paste group had deep scratches and small particles on the surface. The specimens of polishing group had the roughest surface with noticeable scratches, deep grooves, and many irregular granular protrusions. (3) The colony forming unit in the five groups from high to low was: polishing group, polishing paste group, multi-step fine polishing group, fine polishing group, and control group. The colony forming unit was significantly higher in the polishing group than that in the other four groups (P < 0.01). (4) These results show that both the fine polishing and the multi-step fine polishing can effectively improve the finish and reduce the bacteria adhesion on the surface and have a comparable effect to glazing. [ABSTRACT FROM AUTHOR]

Melamine polyphosphate (MPP) was grafted onto the surface of silicon carbide (SiC) particles by silane coupling agent KH-560. The modified SiC (SiC-M) was melt blended with nylon 6 (PA6) to prepare SiC modified PA6 composites (PA6/SiC-M). The effects of SiC-M particle content on the flame retardancy, friction properties and mechanical properties of the composites were analyzed. The results show that the flame retardant MPP is successfully grafted onto the surface of SiC particles. When the mass fraction of SiC-M is 10%, the composite reaches UL94 V-0 level and the limiting oxygen index reaches 29.8%. When the mass fraction of SiC-M is 10%, the friction coefficient of the composite is the largest. When the mass fraction of SiC-M is 4%, the flexural strength of the composite reaches 285 MPa and the tensile strength reaches 51 MPa. The addition of SiC-M can improve the flame retardancy, wear resistance and mechanical properties of the composites. [ABSTRACT FROM AUTHOR]

Based on self-healing technology of closed wall microcapsules in goaf, silicon carbide-phenolic resin (SiC-PF) microcapsules were prepared by in-situ polymerization with epoxy resin E-51 as core material and silicon carbide (SiC) doped phenolic resin as wall material. The microstructure and particle size distribution of the microcapsules were characterized by scanning electron microscopy (SEM) and laser particle size analyzer. The structure of the microcapsules was analyzed by Fourier transform infrared spectroscopy (FTIR). The thermal degradation behavior of the microcapsules was tested by thermogravimetric analyzer (TG). The nanoindentation instrument was used to analyze the capsule wall performance of the microcapsules, and the mass loss rate of the microcapsules was tested at room temperature. The results show that with the increase of SiC content, the particle size of SiC-PF microcapsules is uniform, the thermal stability is good, the performance of capsule wall is greatly improved, and the mass loss rate is small. The initial thermal decomposition temperature of 0.8SiC-PF microcapsules is increased to 279 °C, the carbon residue rate is 12.6%, the rupture load of the capsule wall is 95.49 mN, and the mass loss rate is 1.82% after 100 d at room temperature. The addition of SiC improves the particle shape, thermal stability, capsule wall characteristics and storage stability of PF microcapsules. [ABSTRACT FROM AUTHOR]

Copyright of Refractories / Naihuo Cailiao is the property of Naihuo Cailia (Refractories) Editorial Office 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.)

Copyright of Refractories / Naihuo Cailiao is the property of Naihuo Cailia (Refractories) Editorial Office 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.)