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3D printing“wire-on-sphere”hierarchical sic nanowires/sic whiskers foam for efficient high-temperature electromagnetic wave absorption

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Journal of Materials Science & Technology 2022年第14期109卷 94-104页

作者： Xinyuan Lv Fang Ye Laifei Cheng Litong Zhang Science and Technology on Thermostructural Composite Materials Laboratory Northwestern Polytechnical UniversityXi’an 710072China

Electromagnetic wave absorption(EWA)materials for use in extreme environments are of great ***,sic nanowires/sic whiskers(sic_(nw)/sic_(w))foam with unique“wire-on-sphere”hierarchical structure was developed for efficient high-temperature ***_(w)were assembled to porous sic_(w)spheres via spray drying and then sic_(w)spheres were 3D printed to sic_(w)*** catalyst-free precursor infiltration pyrolysis process was first developed to ensure that sicnwcan intentionally grow in situ on the surface of sic_(w)spheres,thereby achieving“wire-on-sphere”hierarchical structure *** room-temperature,the maximum electromagnetic wave effective absorption bandwidth(EAB_(max))and minimum electromagnetic wave reflection coefficient(RC_(min))of sic_(nw)/sic_(w)foam can reach 4 GHz and-57 dB,***600℃,the EAB_(max)and RC_(min) were 3 GHz and-15 dB,***,even oxidized at 1000-1500℃,sic_(nw)/sic_(w)foam can still retain EAB_(max)ranging from 2.7 to 3.9 GHz and RC_(min)ranging from-16 dB to-64 dB,because the formation of SiO_(2)layer with appropriate thickness can boost interfacial polarization and regulate impedance *** sic_(nw)/sic_(w)foam also shows the flexural strength as high as 17.05 *** results demonstrate that the sic nw/sic_(w)foam is a promising EWA material for applications of harsh *** the material-independent“wire-on-sphere”hierarchical structure and its novel preparation process should find the widespread use in the design and fabrication of high-efficiency EWA micro-nano materials.

关键词： “wire-on-sphere”hierarchical structure sic nanowires sic whiskers 3D printing High-temperature electromagnetic wave absorption

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Synergistically Toughening Effect of sic whiskers and Nanoparticles in Al_2O_3-based Composite Ceramic Cutting Tool Material

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Chinese Journal of Mechanical Engineering 2016年第5期29卷 977-982页

作者： LIU Xuefei LIU Hanlian HUANG Chuanzhen WANG Limei ZOU Bin ZHAO Bin Centre for Advanced Jet Engineering Technologies School of Mechanical EngineeringShandong University School of Mechanical and Electrical Engineering Qilu Institute of Technolegy Key Laboratory of High Efficiency and Clean Mechanical Manufacture of Ministry of Education Shandong University

In recent decades, many additives with different characteristics have been applied to strengthen and toughen Al2O3-based ceramic cutting tool materials. Among them, sic whiskers and sic nanoparticles showed excellent performance in improving the material properties. While no attempts have been made to add sic whiskers and sic nanoparticles together into the ceramic matrix and the synergistically toughening effects of them have not been studied. An Al2O3-sicw-sic np advanced ceramic cutting tool material is fabricated by adding both one-dimensional sic whiskers and zero-dimensional sic nanoparticles into the Al2O3 matrix with an effective dispersing and mixing process. The composites with 25 vol% sic whiskers and 25 vol% sic nanoparticles alone are also investegated for comparison purposes. Results show that the Al2O3-sicw-sicnp composite with both 20 vo1% sic whiskers and 5 vol% sic nanoparticles additives have much improved mechanical properties. The flexural strength of Al2O3-sicw-sicnp is 730＋ 95 MPa and fracture toughness is 5.6 ± 0.6 MPa.m1/2. The toughening and strengthening mechanisms of sic whiskers and nanoparticles are studied when they are added either individually or in combination. It is indicated that when sic whiskers and nanoparticles are added together, the grains are further refined and homogenized, so that the microstructure and fracture mode ratio is modified. The sic nanoparticles are found helpful to enhance the toughening effects of the sic whiskers. The proposed research helps to enrich the types of ceramic cutting tool and is benefit to expand the application range of ceramic cutting tool.

关键词： Al2O3-based ceramic cutting tool materials sic whiskers sic nanoparticles mechanical properties,toughening and strengthening mechanisms

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Effect of sic whiskers on the oxidation protective properties of sic coatings for carbon/carbon composites

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Rare Metals 2006年第1期25卷 58-62页

作者： SHI Xiaohong LI Hejun FU Qiangang LI Kezhi ZHANG Xiulian The Key Laboratory of Superhigh Temperature Composites Northwestern Polytechnical University Xi＇an 710072 China

In order to effectively employ the unique high temperature mechanical properties of carbon/carbon composite substrates, sic coatings reinforced by sic whiskers were prepared by pack cementation method. The effect of sic whiskers on the oxidation resistance properties of the single-layer coating and double-layer coating was investigated. sic whiskers in the single-layer sic coating have little effect on the anti-oxidation property but obviously improve the thermal shock property. The double-layer coating with inner-layer reinforced coating exhibits more perfect anti-oxidation ability than the double-layer coating with sic inner-layer coating.

关键词： carbon/carbon composites sic coating oxidation protection sic whiskers

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Microstructure of sic whiskers with Different Cross-sections Perpendicular to the whiskers Axis

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Journal of Materials Science & Technology 1992年第1期8卷 1-8页

作者：宁小光吕毓雄胡魁毅叶恒强 Laboratory of Atomic Imaging of Solids Institute of Metal ResearchAcademia SinicaShenyang 110015China

Microstructure of β-sic whiskers with differ- ent cross-sections perpendicular to their growing direction was studied in detail by transmission elec- tron microscopy (TEM).It was indicated that there were three types of cross-sections:round, hexagonal and *** whiskers with round and hexagonal cross-sections had a high density of planar faults lying on the (111) close packed planes perpendicular to the whisker *** existed a few stacking faults on the other {111} planes in some hexagonal *** whiskers with bicrystals were also found in hexagonal whiskers. The microstructure of trigonal sic whiskers was basically perfect but there were a few intrinsic stack- ing faults on the (11) planes (mostly) and (111) *** characters of electron diffraction pat- terns of β-sic whiskers with different cross-sec- tions were reasonably analyzed using a reciprocal space model with continuous diffraction streaks along the [111] reciprocal direction.

关键词： microstructure sic whiskers TEM

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Preparation and Characterization of sic whiskers from Rice Husks in Argon Atmosphere

Preparation and Characterization of Sic Whiskers from Rice H...

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The 3rd International Conference of Bionic Engineering(ICBE’10)

作者： Suqiu Jia1 2 Jin Tong1 Yunhai Ma1 1 Key Laboratory of Bionic Engineering (Jilin University) Ministry of Education P.R.China 2 Key Laboratory of Advanced Structural Materials Ministry of Education Changchun University of Technology Changchun 130012 P.R China

sic whiskers were prepared through carbonthermal reduction in two steps. Firstly raw rice husks （RHs） were pyrolysed in a graphite vacuum furnace at 460℃ for 2 hours and coked rice husks were pyrolysed at 1400℃ in argon atmosphere. Scanning electron microscopy （SEM）, X-ray diffraction （XRD）, transmission electron microscopy （TEM） was employed to characterize the morphology and phase composition of sic whiskers. The result shows that the diameters of sic whiskers range in 20-200 nm and their lengths are in the range from hundreds of microns to several millimeters. The whiskers are straight and slightly rough and consist of β-sic crystals with bamboo-like structure. Vapor-solid （VS） mechanism plays a key role at the early stage of sic formation and VLS mechanism and vapor phase mechanism of the whiskers are involved during the growth of sic whiskers.

关键词： sic whiskers Rice husks Pyrolyse

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In-situ Synthesis of sic and β-Si3Al3O3N5 whiskers in Alumina Carbon Based Materials

In-situ Synthesis of SiC and β-Si3Al3O3N5 Whiskers in Alumi...

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中国材料大会2012

作者： Xiangcheng Li Boquan Zhu Fei Zhao The State Key Laboratory Cultivation Base of Refractories and Ceramics Wuhan University of Science and Technology

ISBN: (纸本)9783037856079

sic whiskers are the common reinforced phases in alumina carbon refractories. In this paper, the effect of transition metal catalyst on the evolution of matrix phase and the formation of β-Si3Al3O3N5 whiskers were studied. It was found that the whiskers of both sic and β-Si3Al3O3N5 in alumina carbon materials with the catalyst in reducing atmosphere were generated. The existence of catalyst can promote the nitriding process of Si metal and facilitate the formation of β-Si3Al3O3N5 whiskers. The growth mechanism of both sic and β-Si3Al3O3N5 whiskers agrees with the vapor-liquid-solid model.

关键词： Alumina carbon refractories sic whiskers β-Si3Al3O3N5 whiskers Catalyst.

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FRACTURE BEHAVIOUR OF sic WHISKER REINFORCED Al COMPOSITES

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Acta Metallurgica Sinica(English Letters) 1989年第12期2卷 403-408页

作者： CAO Li JIANG Chiping YAO Zhongkai LEI Tingquan Harbin Institute of Technology,Harbin,China

The dynamic tensile processes of silicon carbide whisker reinforced Al composite(sic_w/Al) with 22% V_f have been in situ observed with a scanning electron microscope equipped with a tensile *** results show that a number of microcracks have formed as the tensile stress increases to 180～190 *** form in most cases at the whisker *** frac- ture behaviour of sic_w/Al composite observed has been explained theoretically.

关键词： composite fracture stress distribution sic whiskers aluminum

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