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Influence of carbon preform density on the microstructure and ablation resistance of cLVD-c/c-Zrc-Sic composites

cORROSION ScIENcE 2021年 190卷

作者： He, Qinchuan Li, Hejun Tan, Qing Lu, Jinhua Wang, Yiqun Chengdu Univ Technol Coll Mat & Chem & Chem Engn Chengdu 610059 Peoples R China Shaanxi Univ Sci & Technol New Style Think Tank Shaanxi Univ Res Ctr Auxiliary Chem & New Mat Dev Xian 710021 Peoples R China Northwestern Polytech Univ Sch Mat Sci & Engn Xian 710072 Peoples R China

In chemical liquid vapor deposition (cLVD) technique, carbon preform density is a crucial factor to control the microstructure of c/c-Zrc-Sic composites, which also determines the ablation resistance. The effects of preform density on the microstructure and ablation behavior of cLVD-c/c-Zrc-Sic composites were studied. Results demonstrated the composites prepared from the preform with a density of 0.91 g/cm(3) showed a dense microstructure and proper ceramic content. Under an oxyacetylene flame, the composites displayed an excellent ablation resistance. The good ablation resistance was ascribed to the proper preform density, which promoted the formation of uniform and continuous protective layer of ZrO2-SiO2.

关键词： cLVD process Preform density c c-Zrc-Sic Microstructure Ablation resistance

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Quantification method for extrapolation errors of constitutive models and a demonstration on c/Sic composite

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cOMPOSITE STRUcTURES 2021年 273卷

作者： Wang, Pengyuan Yang, Qiang Gao, Bo Yi, Fajun Meng, Songhe Harbin Inst Technol Natl Key Lab Sci & Technol Natl Def Adv Composite Harbin 150001 Heilongjiang Peoples R China Harbin Inst Technol Postdoctoral Res Ctr Mat Sci & Engn Harbin 150001 Heilongjiang Peoples R China

Phenomenological constitutive models are always used in structural analysis due to its simplicity in modeling and implementation. However, these models are always fitted from limited experimental curves, leading to errors and insufficient confidence in analysis results. Previous constitutive model error quantification methods rely on a-posteriori experimental observations. In this paper, a priori error quantification method for extrapolation errors of constitutive models is established. Gaussian Process models are fitted with stress states as inputs and strains as outputs. Prediction variations of the GP model are used as the error indicator. The method naturally leads to zero error at known load cases and larger error at load cases away from existing experimental data. It can be integrated with FEM analysis easily and provide error visualization capabilities along with stress fields. Stress states at large error areas provide directions for further experiments and constitutive refinement. The method is demonstrated on the constitutive model and FEM analysis of a c/Sic frame and showed good validity.

关键词： constitutive law c Sic composite Model extrapolation Model errors

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Detection on the coating peeling of Sic coated c/c composites using infrared thermal-wave tomography

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INFRARED PHYSIcS & TEcHNOLOGY 2021年 114卷

作者： Dong, Boyuan Wang, Fei Song, Peng Liu, Yang Wang, Yonghui Wei, Jiacheng Liu, Junyan Wang, Yang chen, Mingjun Liu, Guobin Harbin Inst Technol Sch Mechatron Engn Nangang Dist Xidazhi St 92 Harbin 150001 Heilongjiang Peoples R China State Key Lab Robot & Syst HIT Harbin 150001 Peoples R China Harbin Inst Technol Sch Instrument Sci & Engn Harbin 150001 Peoples R China CASIC Acad 6 Inst 41 Hohhot 010010 Peoples R China

The coating damage of Sic-coated carbon?carbon (c/c) composite is directly influenced on the anti-oxidation attack and ablation performances of carbon?carbon (c/c) composite substrate. It is unprecedentedly reported that infrared thermal-wave tomography (IR-TWT or TWT) approach with laser as external stimulation source is successfully employed for the evaluation of the Sic damage coated on the c/c composite substrate. The stimulation laser intensity is varied according to a chirp-pulsed chain, and employed to induce the chirp-pulsed radar thermal-wave signal. The thermal-wave signals of Sic-coated c/c composite dependence on coating thickness degradation and substrate material are deeply analyzed by using of one dimensional (1D) thermal-wave transfer analytical model. A temporal amplitude of thermal-wave signal as function of delay time is obtained by using of dual-orthogonal demodulation (DOD) algorithms, and it can be employed to represent thermal-wave transmission and to perform tomography. Experimental results confirm that TWT can be used to accurately and reliably assess the Sic coating damage characterization from the c/c composite substrate.

关键词： Infrared thermal-wave tomography chirp-pulsed radar Sic-coated c c composite

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About c/539W1 and c/1245D1 as the parent comet of 15-BOOTIDS

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PLANETARY AND SPAcE ScIENcE 2021年 204卷

作者： Martinez, M. J. Marco, F. J. Univ Politecn Valencia Dept Matemat Aplicada IUMPA Valencia 46022 Spain Univ Jaume 1 Dept Matemat IMAC Castellon de La Plana 12004 Spain

In a recent paper published in this journal it was presented an interesting study on the 2019 outburst of the 15Bootids and it was suggested the possibility that comet c/539W1 was the parent comet of this meteor shower. It was also deducted from the method employed that this parent comet could have had a first passage through perihelion around the year AD1260. In this paper, we review both assumptions and we propose the possibility that the previous perihelion passage of the parent comet of the 15-Bootids was observed and recorded as c/ 1245D1.

关键词： celestial mechanics Meteoroids Meteors Small bodies comets c c Meteor showers 15-Bootids

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Laser ablation behavior of c/Sic composites subjected to transverse hypersonic airflow

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cORROSION ScIENcE 2021年 183卷

作者： Wang, Zhe Wang, Jiangtao Song, Hongwei Yuan, Wu Liu, Yuwen Ma, Te Huang, chenguang Chinese Acad Sci Key Lab Mech Fluid Solid Coupling Syst Inst Mech Beijing 100190 Peoples R China Univ Chinese Acad Sci Sch Engn Sci Beijing 100049 Peoples R China Yanshan Univ Sch Environm & Chem Engn Qinhuangdao 066004 Hebei Peoples R China

Laser ablation behaviors of c/Sic composites were examined in a hypersonic wind tunnel. Parallel laser ablation tests under static air were also conducted, and the ablation behaviors of these two conditions were compared. Mass ablation rates were augmented by 4?9 times when subjected to the hypersonic airflow. Ablation morphologies were significantly different in the micro and macro scales, and the needle-like microstructure of carbon fibers under static air turned to be rough and tattered under the hypersonic airflow. The accelerated ablation rate and the peculiar ablation micro-morphologies were mainly attributed to the strong mechanical erosion induced by hypersonic airflow.

关键词： Laser ablation (c) c Sic composite (A) Hypersonic airflow (c) Ablation morphology (c) Mechanical erosion (c)

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TEM study on the morphology and interface microstructure of c/c-Sic composites fabricated by liquid infiltration

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MATERIALS cHARAcTERIZATION 2021年 175卷

作者： Zhang, K. X. Guo, X. S. cheng, Y. X. Zhang, F. Q. He, L. L. Guilin Univ Elect Technol Guangxi Collaborat Innovat Ctr Struct & Property Sch Mat Sci & Engn Guangxi Key Lab Informat Mat Guilin 541004 Peoples R China Pingxiang Univ Engn & Technol Res Ctr Environm Protect Mat & Equ Pingxiang 337055 Peoples R China Chinese Acad Sci Inst Met Res Shenyang Natl Lab Mat Sci Shenyang 110016 Peoples R China Cent South Univ Sci & Technol High Strength Struct Mat Lab Changsha 410083 Peoples R China

carbon fiber reinforced carbon and silicon carbide dual matrix composites (c/c-Sic) have been widely used in aerospace field thanks to their superior high temperature properties. However, the interfacial microstructure of the composites is still not thoroughly understood in details. In this study, we focus on the morphology of the reaction-formed Sic and the interfacial microstructure between carbon and Sic in the c/c-Sic composites fabricated by liquid silicon infiltration performed at 1700 ?c. The fine microstructure of the composites was investigated systematically by using transmission electron microscopy. The results show that two main types of interface are formed in the composites: (i) the fine-grained Sic is formed adjacent to the pyrolytic carbon, followed by a layer of coarse-grained Sic;and (ii) some extremely large Sic grains are formed directly on the pyrolytic carbon, and different pyrolytic carbon coatings can be connected by these large Sic grains. Additionally, some subgrains with grain size of a few tens of nanometers or even smaller can be found near the pyrolytic carbon or carbon fibers. The formation mechanism of the Sic/carbon interface is also discussed based on the fine microstructure observed.

关键词： composites c c-Sic Liquid silicon infiltration TEM Morphology Interfacial microstructure

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Soluble salt assisted synthesis of hierarchical porous carbon-encapsulated Fe3c based on MOFs gel for all-solid-state hybrid supercapacitor

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cHEMIcAL ENGINEERING JOURNAL 2021年 419卷

作者： Zhang, Yidong Shao, Rong Xu, Wei Ding, Jianfei Wang, Yuan Yan, Xiuhua Shi, Wenyan Wang, Min Yancheng Inst Technol Sch Chem & Chem Engn Yancheng 224051 Peoples R China Yancheng Teachers Univ Sch Chem & Environm Engn Yancheng 224002 Peoples R China

Hierarchical porous materials receive extensive attention due to their excellent electrode kinetic performance. Herein, a facile strategy is presented to fabricate hierarchical porous supercapacitor materials using Nacl-assisted MOFs gel as a structure-directing template. By controlling the additive amount of Nacl, hierarchical porous carbon-encapsulated Fe3c with tailored pore size distribution has been obtained with a high specific capacity of 184.1 mAh g- 1 (602.3F g-1) at a current density of 1 A g-1. The analysis of kinetics and impedance indicates that the tailored porosity can provide broad ion diffusion pathway and low charge-transfer resistance. Meanwhile, seawater was used instead of Nacl for preparing hierarchical porous carbon with good capacitive performance. When evaluated their practical applications, the assembled all-solid-state hybrid supercapacitor delivers a high energy density of 30.6 W h kg-1 at a power density of 600 W kg-1, and even maintains an energy density of 15.5 W h kg-1 at a power density of 12000 W kg-1 with 86.5% capacity retention after 10,000 cycles. This work is anticipated to open up a new route of using MOFs gel and water-soluble salts for designing hierarchical porous electrodes materials, which pave the way for advanced utilization of MOFs gel and seawater.

关键词： MOFs gel Supercapacitor Fe3c c Salt assisted synthesis Hierarchical porous structure

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A comprehensive investigation of phase evolution of Al-Si coating during the prolonged aging at 650 °c

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cORROSION ScIENcE 2021年 189卷

作者： Zhao, Zhiyu Lu, Jintao Huang, Jinyang Wang, Qiannan Zhang, Xingpu Wang, Jiangwei Zhejiang Univ Ctr Electron Microscopy Sch Mat Sci & Engn Hangzhou 310027 Peoples R China Zhejiang Univ State Key Lab Silicon Mat Sch Mat Sci & Engn Hangzhou 310027 Peoples R China Xian Thermal Power Res Inst Co Ltd State Key Lab Coal Based Clean Energy Xian 710032 Peoples R China China Acad Engn Phys Inst Fluid Phys Lab Shock Wave & Detonat Phys Mianyang 621900 Sichuan Peoples R China

Microstructural evolution of silicon-modified aluminide coating during 10,000 h aging at 650 degrees c was systematically investigated. Upon aging, the coating was gradually transformed from a multilayered structure to a double-layer structure, with the matrixes of Al-Fe-Si compounds and beta-(Fe, Ni)Al in the two layers, respectively. An internal oxide layer formed below the coating, while the thickness of interdiffusion zone (IDZ) increased as the inward diffusion of Al. Precipitate evolutions in both the coating and the IDZ were discussed, which clarifies the microstructural origin of long-term stability of the coating. The phase evolution of Al-Si coating in prolonged aging was further discussed.

关键词： A Metal coatings A Stainless steel B SEM B TEM c Segregation

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Pulsed Dc Sputtering of Highly c-Axis AlN Film on Top of Si (111) Substrate

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PHYSIcA STATUS SOLIDI B-BASIc SOLID STATE PHYSIcS 2021年第6期258卷

作者： Iqbal, Abid Walker, Glenn Hold, Leonie Fernandes, Alanna Iacopi, Alan Mohd-Yasin, Faisal Griffith Univ Queensland Micro & Nanotechnol Ctr Nathan Qld 4111 Australia Univ Engn & Technol Dept Elect Engn Peshawar Kpk Pakistan Bluglass Ltd 74 Asquith St Silverwater NSW 2128 Australia

Herein, pulsed Dc sputtering of the AlN film on top of the Si (111) substrate is reported on. First, major articles on the reactive sputtering of AlN film on top of Si (111) substrate that were published in the past 30 years are tabulated. Then, a sputtering recipe to produce a consistent and high-crystal-quality (as measured by the full width at half maximum [FWHM] of rocking curve) AlN film across varying substrate temperatures (250-450 degrees c) and sputtering powers (1200-2400 W) is proposed. In addition, the influence of both parameters to in-plane stress is demonstrated, in agreement with similar trends that have been reported in the literature for AlN films on other substrates. The best sample is produced at a substrate temperature of 350 degrees c and sputtering power of 1800 W, resulting in FWHM of rocking curve of 1.84 degrees, surface roughness of 1 nm, and in-plane stress of +300 MPa. The recipe herein is beneficial for integration of AlN thin film in complementary metal-oxide-semiconductor and micro-electromechanical system processes.

关键词： aluminum nitride c -axis film silicon substrate sputtering stress

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Parametric Study of Pt/c-catalysed Hydrothermal Decarboxylation of Butyric Acid as a Potential Route for Biopropane Production

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ENERGIES 2021年第11期14卷

作者： Razaq, Iram Simons, Keith E. Onwudili, Jude A. Aston Univ Energy & Bioprod Res Inst Coll Engn & Phys Sci Birmingham B4 7ET W Midlands England SHV Energy Sustainable Fuels NL-2132 JL Hoofddorp Netherlands Aston Univ Dept Chem Engn & Appl Chem Coll Engn & Phys Sci Birmingham B4 7ET W Midlands England

Sustainable fuel-range hydrocarbons can be produced via the catalytic decarboxylation of biomass-derived carboxylic acids without the need for hydrogen addition. In this present study, 5 wt% platinum on carbon (Pt/c) has been found to be an effective catalyst for hydrothermally decarboxylating butyric acid in order to produce mainly propane and carbon dioxide. However, optimisation of the reaction conditions is required to minimise secondary reactions and increase hydrocarbon selectivity towards propane. To do this, reactions using the catalyst with varying parameters such as reaction temperatures, residence times, feedstock loading and bulk catalyst loading were carried out in a batch reactor. The highest yield of propane obtained was 47 wt% (close to the theoretical decarboxylation yield of 50 wt% on butyric acid basis), corresponding to a 96% hydrocarbon selectivity towards propane. The results showed that the optimum parameters to produce the highest yield of propane, from the range investigated, were 0.5 g butyric acid (0.57 M aqueous solution), 1.0 g Pt/c (50 mg Pt content) at 300 degrees c for 1 h. The reusability of the catalyst was also investigated, which showed little or no loss of catalytic activity after four cycles. This work has shown that Pt/c is a suitable and potentially hydrothermally stable heterogeneous catalyst for making biopropane, a major component of bioLPG, from aqueous butyric acid solutions, which can be sourced from bio-derived feedstocks via acetone-butanol-ethanol (ABE) fermentation.

关键词： hydrothermal decarboxylation butyric acid biopropane bioLPG catalysis Pt c

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