CERAMICS INTERNATIONAL
·
2021
·
IF 4.527
Zhiqiang Zhou,Xiumin Chen,Zhongqian Zhao,Youli Xu,Bingyang He,Li Liu,Bin Yang,Baoqiang Xu,Dachun Liu
The Ab initio molecular dynamics (AIMD) simulation was adopted to elucidate the alumina vacuum carbothermal reduction and nitridation (VCRN) reaction mechanism, and an experimental method was adopted to verify the AIMD results. According to the results, the VCRN reaction occurs only when N 2 is adsorbed on both the C and Al atoms. C plays two important roles during the reaction of alumina VCRN: one is to act as a charge exchange carrier for N and Al atoms to catalyze N 2 molecule decomposition, and the other is to react with O atoms and reduce Al 2 O 3 .
研究领域:
材料科学
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化学工程
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产品关联
DOI
高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2023
·Vol. 107
·期 1
·16-23
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IF 3.9
Shuo Zhao,Songmo Du,Siyuan Sun,Fei Li,Zhanglin Chen,Shijia Zhang,Xiaoshan Ning,Wenbin Cao,Kexin Chen,Konstantin Smirnov,Jie Zhang,Guanghua Liu
β-Si 3 N 4 powder with well-dispersed spherical particles was synthesized by liquid-phase modified carbothermal reduction and nitridation. The influence of the type and content of additives on the particle morphology was investigated. The liquid phase formed at the reaction temperature modifies the morphology of the Si 3 N 4 powder. The Si 3 N 4 products precipitated along the liquid-solid interface, thus forming a spherical morphology and promoting the transformation from α-Si 3 N 4 to β-Si 3 N 4 . The type of additives has a strong influence on the formation temperature and viscosity of the liquid phase and hence affects the product morphology. In the samples with CaF 2 and CaO additives, sufficient liquid phase occurred and spherical particles were obtained. In the sample with Y 2 O 3 , however, the liquid phase was insufficient due to the higher formation temperature, thus resulting in an irregular particle morphology.
研究领域:
材料科学
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化学工程
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产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2019
·
IF 3.45
Qiang Zhi,Bo Wang,Shan Zhao,Zhao Zhang,Yu-Chen Deng,Nan-Long Zhang,Jian-Feng Yang
Highly porous Si 3 N 4 ceramics have been prepared via a novel carbothermal reduction-nitridation (CRN) reaction between carbon nanotubes (CNTs) and SiO vapor in a N 2 atmosphere. The green bodies consisted of 49.0 wt% CNT, 40.4 wt% α-Si 3 N 4 as seed and 10.6 wt% Y 2 O 3 as sintering additive, and SiO powders were located under the green bodies during sintering. By heating at temperatures ranging from 1550 to 1650 °C, fibrous β-Si 3 N 4 nanograins were obtained. Complete reaction was achieved after soaking at 1650 °C, and a mean grain diameter of approximately 290 nm and aspect ratio of as high as 20 were obtained, and a porosity of 73% was reached due to the low density of the green bodies. The bending and compressive strengths were up to 62 MPa and 82 MPa, respectively, which were higher than the values in the literature, as a result of the fine elongated fibrous β-Si 3 N 4 grains. It should be noted that the Si 3 N 4 ceramics exhibited a large strain to failure and ‘pseudoplastic’ deformation behavior during the compressive test, which was attributed to the high porosity.
研究领域:
材料科学
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陶瓷工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF LUMINESCENCE
·
2015
·
IF 2.719
Qian Liu,Qi Lu,Guanghui Liu,Qinhua Wei
β-SiAlON:Eu 2+ phosphors synthesis usually requires higher temperatures and higher nitrogen pressure conditions. In the present research, a low temperature technique has been developed to synthesize both β-SiAlON and Eu-doped β-SiAlON fibers by electrospinning combined with carbothermal reduction nitridation (CRN). The carbon sources used as reductant in CRN procedure have been optimized to effectively produce a well-crystallized β-SiAlON phase at lower temperatures of 1370–1500 °C. Additionally, through adding sucrose and covering activated carbon powders on the top of fiber precursor layers, the highly-pure β-SiAlON and β-SiAlON:Eu 2+ fibers could be obtained. The pyrolysis behavior of fiber precursors, crystalline phase, morphology, and UV excited luminescence properties of the produced ceramic fibers were also studied by using TG–DSC measurement, XRD analysis , SEM observation, and spectrometer method. The resultant fibers exhibit a smooth surface and an uniforme morphology with a substantial length. Moreover, the β-SiAlON:Eu 2+ fibers thus prepared show a blue light emission peaked at 470 nm under UV excitation.
研究领域:
材料科学
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光学
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产品关联
DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2021
·
IF 5.302
Lei Han,Longhao Dong,Haijun Zhang,Faliang Li,Liang Tian,Guangqiang Li,Quanli Jia,Shaowei Zhang
With the rapid development of energy sources and aerospace engineering, high-performance thermal insulation materials with multiple functions are attracting more and more attentions. Non-oxide ceramic aerogels have application potential in thermal insulation under harsh conditions owing to their good thermal insulation performance and chemical stability. In this work, TiN aerogels were prepared by a combined freeze-casting and carbothermal reduction-nitridation method utilizing TiO 2 and chitosan as raw materials, at 1473 K for 3 h, with a C/TiO 2 molar ratio of 3/1. They showed a specific surface area of 167 m 2 /g and ultralow density of 0.07 g/cm 3 (the relative density of 1.3 %). Their thermal conductivity value was only 0.166 ± 0.0054 W/(m K at 673 K (TiO 2 solid content of 5 wt%). Moreover, the prepared aerogels possessed reasonably high mechanical strength and good high-temperature service performance, suggesting that they can be used under high-temperature conditions as an insulation material.
研究领域:
材料科学
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航空航天工程
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产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Yang Wang,Wenjie Yuan,Weijian Han,Jianwei Gao,Hao Li,Tong Zhao
A simple and scalable approach to fabricate monodispersed Si 3 N 4 hollow microspheres (Si 3 N 4 HMs) with uniform spherical structures is proposed in this study. This approach involves spray drying of Si 3 N 4 precursor, followed by carbothermal reduction nitridation. The homogeneous Si 3 N 4 precursor was first obtained by mixing phenolic resins and silicon resins, which are carbon and silicon sources, respectively. The spray drying process was then tuned by regulating the viscosity of the precursor by adding polyvinyl butyral in an appropriate ratio. Next, the hollow precursor microspheres were pyrolyzed at 1500 °C for 6 h, while ensuring that the shells of the obtained Si 3 N 4 HMs remained intact. Porous Si 3 N 4 ceramics with different contents of Si 3 N 4 HMs were then prepared using the gel-casting method. It was observed that the densities and dielectric constants of the porous Si 3 N 4 ceramics decreased with an increasing Si 3 N 4 HMs content. Thus, the proposed approach can be used for the synthesis of Si 3 N 4 HMs, that can be further processed into ceramic materials with both low densities and dielectric constants.
研究领域:
材料科学
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陶瓷工程
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产品关联
DOI
高影响因子
MATERIALS LETTERS
·
2016
·
IF 2.437
Shen Qi,Xiaojian Mao,Xiaokai Li,Minghui Feng,Benxue Jiang,Long Zhang
Wurtzite-structured aluminum nitride (AlN) hexagonal bipyramids were prepared via a carbothermal reduction nitridation method using alumina and carbon as the raw materials. The growth of the AlN hexagonal bipyramids is dominated by the vapor-solid (VS) mechanism with Fe 2 O 3 , SiO 2 and Na 2 O acting as mineralizers under alternate gas pressures. The preferred growth direction of the AlN hexagonal bipyramids is [0001]. Photoluminescence spectra of the AlN hexagonal bipyramids showed near-band edge emission at 512 nm at room temperature. The AlN hexagonal bipyramids might be useful for optical micro-devices.
研究领域:
材料科学
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光学工程
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DOI
高影响因子
METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE
·
2023
·Vol. 54
·期 11
·4332-4341
·
IF 2.8
Li Hang,Dong Longhao,Duan Hongjuan,Huang Zhong,Li Yage,Liu Xuefeng,Huang Ren,Jia Quanli,Ye Hang,Zhang Haijun,Zhang Shaowei
Non-oxide ceramic aerogel draws increasing attention in area of thermal insulation because of its low density, high temperature resistance and good chemical/thermal stability. Here, a BCN-TiN composite aerogel was prepared by an in-situ carbothermal reduction/nitridation method, using melamine (C 3 N 6 H 6 ), boric acid (H 3 BO 3 ), chitosan ((C 6 H 11 NO 4 ) n ) and titanium dioxide (TiO 2 ) as raw materials. The aerogel prepared at 1473 K showed a porosity high up to 97.6 pct with a density of 0.05 g/cm 3 . When testing at a temperature of 673 K, the thermal conductivity value of as-obtained composite aerogel was as low as 0.135 W/(m K). Moreover, the lightweight BCN-TiN aerogel had the high-temperature stability (at least 1473 K) and good compression strength, which ensures it a potential high-temperature insulation material in inert atmosphere. Graphical Abstract
研究领域:
材料科学
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热能工程
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产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2020
·
IF 3.83
Qiang Zhi,Bo Wang,Shan Zhao,Zhao Zhang,Yu-Chen Deng,Bao-Qiang Hou,Nan-Long Zhang,Jian-Feng Yang
Si 3 N 4 ceramic with ultrafine fibrous grains are expected to exhibit remarkable mechanical properties . In this work, highly porous Si 3 N 4 ceramic monoliths composed of ultrafine fibrous grains were developed via a novel vapor-solid carbothermal reduction nitridation (V-S CRN) reaction between SiO vapor and green bodies comprised of carbon nanotubes (CNTs), α-Si 3 N 4 diluents and Y 2 O 3 in a N 2 atmosphere. The unique fibrous grains-interconnected structure was developed through in-situ formation of Si 3 N 4 and following liquid phase sintering . The porous Si 3 N 4 monoliths with porosity of 61–78% was developed by controlling the contents of α-Si 3 N 4 diluents and densities of the CNT green bodies. With increasing of the α-Si 3 N 4 contents, Si 3 N 4 fibrous grains with an aspect ratio of approximate or higher than 20 could be achieved, and the grains were gradually refined. For the samples with 40 wt% α-Si 3 N 4 , the minimum mean grain diameter and pore size of 164 nm and 0.79 μm were achieved, respectively, and the resultant porous Si 3 N 4 monolith exhibited a flexural strength of as high as 73–102 MPa with the porosity of 61–73%, which is much higher than that of the reported in literature. The improvement of mechanical strength could be attributed to the densely interconnected bird's nests structure formed by the ultrafine fibrous grains. The effects of the α-Si 3 N 4 diluents on the resulting porous Si 3 N 4 monolith via this method were analyzed.
研究领域:
材料科学
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陶瓷工程
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产品关联
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2023
·Vol. 34
·期 21
·1-15
·
IF 2.8
Lu Jiaqi,Li Runkang,Cui Yi,Wang Ronglin,Lv Dongfeng,Wei Yingna,Chen Yuejun,Wei Hengyong,Bu Jinglong
Zirconium nitride nanofibers were synthesized by electrospinning method combined with carbon thermal reduction nitridation process, with zirconium chloride octahydrate and polyvinylpyrrolidone as raw materials. The phase composition, morphology and pore structure of the as-prepared nanofibers were analyzed by XRD, XPS, SEM, TEM and BET. In addition, the microwave absorption properties were measured using transmission line theory utilizing a vector network analyzer of zirconium nitride nanofibers/paraffin composites with different filler loadings. The results show that the as-prepared nanofibers are ZrN phase. The zirconium nitride nanofibers contain residual oxygen and carbon to form Zr(N,C,O) solid solution. The average diameter of the nanofibers is approximately 300 nm. There are particles distributed in it and the particle size ranges from 100 to 200 nm. The specific surface area of zirconium nitride nanofibers is 176.7 m 2 /g, and their pore volume is 0.26 cc/g. The pore sizes are mainly distributed at 3 nm. The granular structure and abundant pores of zirconium nitride nanofibers provide suitable conditions for impedance matching, interfacial polarization, multiple reflections, and scattering. These nanofibers exhibit excellent microwave absorption performance, achieving an optimum reflection loss of − 55.11 dB at a thickness of 1.55 mm with an effective absorption bandwidth of 3.51 GHz when the filler loading is 35 wt%. This study suggests that zirconium nitride nanofibers with good microwave absorption performance have the potential as novel transition metal nitride microwave absorption candidate materials.
研究领域:
材料科学
·
纳米技术
·
微波吸收材料
·
陶瓷
·
电磁功能材料
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2019
·
IF 3.45
Maomao Ding,Tun Wang,Benjamin Maerz,Stuart Robertson,Zehan Sun,Lingcong Fan,Ying Shi,Houzheng Wu
Aluminum oxynitride (γ-AlON) powders were synchronously synthesized by carbothermal reduction-nitridation (CRN) and high-temperature solid state reaction (SSR) methods. Twin structures existing in γ-AlON powders and transparent AlON ceramics were investigated by systematically employing electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM). It was found that the twin structures in synthetic powder and transparent ceramics exhibit quite different microstructural features; binary twin structures were widely observed in powders and ceramics, whereas the sandwich-like twin structure was produced only in transparent ceramics. High-resolution electron backscattered diffraction (HREBSD) was used to determine the residual elastic stress distributions in AlON powders and ceramics. Discrepancies in the magnitude and distribution of the residual stress between binary twins and sandwich-like twins were fully clarified. The formation of two kinds of twins in powders and ceramics was discussed in detail. The Vickers hardness and its corresponding indentation size effect (ISE) were studied in CRN-AlON and SSR-AlON ceramics. The effects of the twin structure on the Vickers hardness and fracture toughness were investigated simultaneously.
研究领域:
材料科学
·
陶瓷工程
·
固体化学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）