ENERGY & FUELS
·
2019
·
IF 3.021
Jing Sun,Zhenyu Jiang,Ke Wang,Faqi Li,Zhanlong Song,Wenlong Wang,Xiqiang Zhao,Yanpeng Mao
Catalytic hydrogenation provides an important pathway for converting environmentally toxic phenol into less oxygenated and more stable useful chemical feedstock for the production of nylon and multicomponent diesel fuel. In this study, an innovative microwave–SiC-assisted heating technology was adopted to induce the vapor-phase catalytic hydrogenation of phenol over a Pd catalyst supported on Zr/Ce oxide. The H2 flow rate, catalyst support, and reaction temperature influenced the phenol conversion as well as product yield and selectivity. At a modest reaction temperature of 200 °C, the hydrogenation of phenol produced a mixture of cyclohexanol (COL) and cyclohexanone (CONE), and the COL/CONE molar ratio was influenced by the catalyst supports in the following order: Pd/CeO2 > Pd/ZrCeO2 > Pd/ZrO2. Under identical experimental conditions, the microwave–SiC-assisted hydrogenation exhibited superior performance over conventional hydrogenation in terms of both the phenol conversion and product yield. Particularly, the product selectivity of COL was remarkably enhanced for all catalyst types, primarily attributed to the abundant H• radicals, which were induced by electron collision as a result of microwave–SiC interaction, facilitating the hydrogenation of CONE into COL. In general, our innovative microwave–SiC-assisted hydrogenation presented a significant advantage in converting phenol into less-oxygenated compounds, hence providing an important reference for industrial practice.
研究领域:
化学工程
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2015
·
IF 2.605
Haibo Wu,Jie Yin,Yinsheng Li,Yunzhou Zhu,Xuejian Liu,Sea-Hoon Lee,Yiquan Wu,Zhengren Huang
ZrB 2 –SiC foams were prepared from composite poring mechanisms of foaming and solid poring (PAA beads) by the application of a gelcasting technique. The porosities and microstructures of sintered bulks were tailored through changing the solids loading of slurries and the amount of added PAA beads. The increase in solid loading caused high viscosities of slurries, and thus resulted in the reduction of porosity and a tendency to form close pores. With increasing the amount of PAA beads, high porosities (up to 91.4%) and obvious connectivity improvement between bubble-derived pores emerged owing to efficient foaming and presence of bead-derived pores. As the porosity increased, the compressive strength (0.4–8.2 MPa) decreased, and the gas permeability (9.7–62.1×10 −12 m 2 ) augmented because of the effects of bead-derived pores and the increase in window number and size of bubble-bead pores.
研究领域:
材料科学
·
陶瓷工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2024
·
IF 5.8
Yu Zhang,Xu Shen,Qin Ma,Shuang Mu,Shaoming Dong,Jinshan Yang
The wet oxidation behavior of LPS-SiC ceramics as well as the synergistic modification effect of Al 2 O 3 and Y 2 O 3 as sintering aids are investigated. The results show that SiO 2 oxide scale is transformed to aluminosilicate with the addition of Al 2 O 3 , which can inhibit the crystallization of oxide layer and formation of cracks. The aluminosilicate oxide layers have low k l value close to zero, which can reduce the consumption of protective oxide layer under water-containing atmosphere. Y 2 O 3 are mainly transformed to Y 2 Si 2 O 7 to resist the diffusion of oxidative gas. However, with the increase of sintering aids content, the aluminosilicate layer with excessive viscosity limits the emission of gas generated by oxidation and causes many bubbles left in oxide scale which provided rapid channel for oxidative gas. Therefore, LPS-SiC with lower content of sintering aids has better oxidation resistance. This work can provide guidance for the component design of SiC-based ceramics and composites.
研究领域:
材料科学
·
陶瓷工程
✓ 已验证
产品关联
DOI
高影响因子
Journal of Materials Chemistry C
·
2016
·Vol. 4
·期 27
·6466-6472
·
IF 5.066
Xiaoxiao Li,Shanliang Chen,Pengzhan Ying,Fengmei Gao,Qiao Liu,Minghui Shang,Weiyou Yang
Silicon carbide (SiC) is recognized as a promising substitute for the currently used Si for exploring robust pressure sensors with desired high sensitivities and excellent abilities to serve under harsh work conditions. In the present work, we reported the giant piezoresistance effect of p-type 3C-SiC nanowires with B dopants, which were synthesized by catalyst-assisted pyrolysis of polysilazane. The transverse electromechanical properties of SiC nanowires were investigated at loading forces applied using a conductive atomic force microscopy (C-AFM) tip. The resistances of the as-synthesized SiC nanowires exhibit an increase with the increase of compressed stresses at the same bias voltages, representing their negative piezoresistance behaviors. The measured negative piezoresistance coefficient π[10] of the nanowire fell in the range of −8.83 to −103.42 × 10−11 Pa−1 as the applied loading forces ranged from 51.7 to 181.0 nN. The giant gauge factor (GF) could be up to −620.5, which was enhanced by more than 10 times compared to the highest ever reported for SiC nanostructures.
研究领域:
材料科学
·
纳米技术
·
传感器技术
✓ 已验证
产品关联
DOI
高影响因子
Membranes
·
2024
·Vol. 14
·期 5
·117
·
IF 3.3
Yuqi Song,Kai Miao,Jinxin Liu,Yutang Kang,Dong Zou,Zhaoxiang Zhong
Membrane distillation (MD) is considered a promising technology for desalination. In the MD process, membrane pores are easily contaminated and wetted, which will degrade the permeate flux and salt rejection of the membrane. In this work, SiC ceramic membranes were used as the supports, and an Al2O3micro-nano structure was constructed on its surface. The surface energy of Al2O3@SiC micro-nano composite membranes was reduced by organosilane grafting modification. The effective deposition of Al2O3nanoflowers on the membrane surface increased membrane roughness and enhanced the anti-fouling and anti-wetting properties of the membranes. Simultaneously, the presence of nanoflowers also regulated the pore structures and thus decreased the membrane pore size. In addition, the effects of Al2(SO4)3concentration and sintering temperature on the surface morphology and performance of the membranes were investigated in detail. It was demonstrated that the water contact angle of the resulting membrane was 152.4°, which was higher than that of the pristine membrane (138.8°). In the treatment of saline water containing 35 g/L of NaCl, the permeate flux was about 11.1 kg⋅m−2⋅h−1and the salt rejection was above 99.9%. Note that the pristine ceramic membrane cannot be employed for MD due to its larger membrane pore size. This work provides a new method for preparing superhydrophobic ceramic membranes for MD.
研究领域:
材料科学
·
环境工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CERAMICS INTERNATIONAL
·
2018
·
IF 3.057
Faliang Li,Cao Tan,Jianghao Liu,Junkai Wang,Quanli Jia,Haijun Zhang,Shaowei Zhang
Herein, we prepare phase-pure ZrB 2 -SiC composite powders by molten-salt-mediated reduction of ZrSiO 4 /B 2 O 3 /activated carbon mixtures with Mg, showing that the phase composition and morphology of the above composites is influenced by firing temperature, B:Zr and C:Si molar ratios, and the amount of excess Mg. Notably, phase-pure ZrB 2 -SiC powder with a ZrB 2 :SiC weight ratio of ~75:25 could be obtained by 3-h firing at 1200 °C, i.e., at a temperature lower than that used for conventional carbothermal reduction by at least 200 °C. As-prepared ZrB 2 -SiC composites exhibited grain sizes of several microns and comprised SiC nanoparticles well distributed in the ZrB 2 matrix. Finally, the oxidation activation energies of the prepared ZrB 2 and ZrB 2 -SiC powders were determined as 326 and 381 kJ/mol, respectively, which demonstrated that the introduction of SiC improved the oxidation resistance of monolithic ZrB 2 .
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2023
·
IF 5.7
Wei Dang,Linna Zhao,Fuping Li,Chenxi Li,Zhuoli Xu,Xinyuan Zhang,Kang Zhao,Yufei Tang
C/SiC aerogels with both ultra-low thermal conductivity and extremely high strength were fabricated by freeze casting. SiC junctions originated from pyrolysis of polycarbosilane (PCS) were formed between carbon nanofibers (C f ) to enhance the strength of aerogels. The effects of PCS content and total solid content on the phase composition, pore structure , thermal conductivity and compressive property were studied. The fabricated aerogels possess hierarchical pore structure. In the micro-scale, it contains circular pores with size of about 15 µm, while it is mesoporous and macroporous in the nano-scale. Both thermal conductivity and compressive strength increase with the increase in PCS content. Through tailoring PCS content and total solid content, C f /SiC aerogels with porosity of 99.5%, thermal conductivity of 33 mW·m −1 ·K −1 and compressive strength of 7.14 MPa can be obtained. The specific strength of the fabricated C f /SiC aerogels is up to 467.6 MPa/(g/cm 3 ), which is the highest value for ceramic aerogels.
研究领域:
材料科学
·
纳米技术
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2023
·
IF 5.7
Jun-Min Zhang,Xiao-Wu Chen,Jin-Shan Yang,Xiang-Yu Zhang,Yan-Mei Kan,Jian-Bao Hu,Yu-Dong Xue,Hao Qin,Shao-Ming Dong
The poor wet-oxidation resistance limits the long-life service of SiC f /SiC composites as the hot end components of aero-engines. The stability of SiC f /SiC composites under high-temperature wet oxygen environment can be promoted by more robust SiC matrix. In this work, the effect of Y 2 O 3 on the corrosion behaviors of SiC ceramics in flowing O 2 /H 2 O atmosphere at 1400 ℃ was studied. Duo to the continuous Y 2 Si 2 O 7 layer formed on the surface, SiC-Y 2 O 3 ceramics exhibit much better wet-oxidation resistance than original SiC ceramics. During the oxidation process , Y 2 O 3 dispersed in the ceramics migrates to the surface and reacts with SiO 2 to form β-Y 2 Si 2 O 7 . Subsequently, the β-Y 2 Si 2 O 7 aggregates and grows to form a continuous Y 2 Si 2 O 7 layer, inhibiting the corrosion from oxidizing medium to the inner SiC matrix. This study is expected to provide important ideas for the design and structure regulation of wet-oxidation resistant SiC f /SiC composites.
研究领域:
材料科学
·
航空航天工程
✓ 已验证
产品关联
DOI
高影响因子
ACS Nano
·
2023
·
IF 17.1
Xuan Zhang,Jianyong Yu,Cunyi Zhao,Yang Si
SiC is an exceptionally competitive material for porous ceramics owing to its excellent high-temperature mechanical stability. However, SiC porous ceramics suffer from serious structural damage and mechanical degradation under thermal shock due to the hard SiC microstructure and weak bonding networks. Here, we report a scalable interface-engineering protocol to reliably assemble flexible amorphous SiC nanofibers into lamellar cellular meta-aerogels by designing a covalent heterointerface. This approach allows the construction of a strong binding architecture within the resilient nanofiber skeleton network, thereby achieving structurally stable, mechanically robust, and durable SiC porous ceramics. The optimized amorphous SiC meta-aerogels (a-SiC MAs) exhibit the integrated properties of ultralight with a density of 4.84 mg cm–3, temperature-invariant superelastic, fatigue-resistant at low 5% permanent deformation after 1000 cycles of compression, and ultralow thermal conductivity (19 mW m–1 K–1). These characteristics provide a-SiC MAs potential application value in the thermal protection field.
研究领域:
材料科学
·
机械工程
·
纳米技术
✓ 已验证
DOI
高影响因子
APPLIED COMPOSITE MATERIALS
·
2020
·Vol. 27
·期 3
·131-148
·
IF 2.199
Cuiyan Li,Zhao Xu,Haibo Ouyang,Liyuan Chang,Jianfeng Huang,Yijun Liu
Porous C/SiC ceramics were prepared by chemical vapor reaction of SiO and porous C/C composites. The porous C/SiC ceramics presented a hierarchical structured consisted of carbon fibers, SiC layer, microspheres and nanowires. The density of porous C/C composites control the growth of SiC nanowires and nanolayer, and influence the pore size distribution and specific surface area of the porous C/SiC ceramics. The C/SiC samples converting from the C/C composites with a density of 0.46 g/cm 3 possess the superior adsorption properties. The adsorption efficiency can reach 98.2% within 80 min, indicating that C/SiC samples have a promising adsorption property for MB from aqueous solution. Furthermore, the adsorption efficiency after five cycles microwave regeneration still reached 80.2%, which present excellent regeneration stability.
研究领域:
材料科学
·
环境工程
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2014
·
IF 2.307
Yinsheng Li,Jie Yin,Haibo Wu,Ping Lu,Yongjie Yan,Xuejian Liu,Zhengren Huang,Dongliang Jiang
In order to attain high thermal conductivity , SiC was doped with ultra-low amounts of B and C as sintering additives using boric acid together with d -fructose as boron–carbon sources. The contents of in situ generated B and C were both tailored as low as 0.4 wt.%, which can significantly reduce the impurities induced phonon scattering effect. The SiC ceramics were pressureless densified at 2150 °C for 1 h, and some samples experienced subsequent annealing at 1950 °C for 4 h. High thermal conductivities of 180.94 W/(m K) for the as-sintered SiC ceramics and 192.17 W/(m K) for the annealed specimens at room temperature were achieved. The reasons for the high thermal conductivity in the polycrystalline SiC ceramics were specified, based on the close correlation with microstructure.
研究领域:
材料科学
·
陶瓷工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2024
·
IF 5.8
Chuanqing Zhao,Shiqi Xia,Yizhe Lv,Huimin Qi,Shifeng Deng
Based on the micro-nano scale designs for absorbing materials, analyzing the influence of microstructures on absorbing properties is a feasible strategy to achieve efficient lightweight broadband electromagnetic wave absorbers. In this work, the silicon-containing arylacetylene resin, serving as a ceramic polymer precursor, is employed to coat SiO 2 gel. Subsequently, the PSA/SiO 2 aerogel underwent carbothermal reduction and the polymer-derived ceramics process, transforming it into a SiC/C aerogel. This SiC/C aerogel exhibits a low density of 0.2 g/cm³ and a high porosity of 68 %. The rich morphology of SiC/C aerogel is conducive to both interfacial polarization and multiple scattering, resulting in excellent impedance matching and attenuation. With a reflection loss of −52.6 dB and an effective absorption bandwidth of 6 GHz, SiC/C aerogels also achieve effective absorption in both the X and Ku bands. These results may thus be of great significance in guiding the design and mechanism investigation of high-performance.
研究领域:
材料科学
·
电磁学
✓ 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）