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Corrosion behavior of SiC foam ceramic reinforced Al-23Si composites in NaCl solution

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Journal of Central South university 2017年第9期24卷 1934-1940页

作者：诸建彬闫洪叶何远艾凡荣 School of Mechanical Electrical engineering Nanchang University School of Mechanical Electrical engineering Nanchang Institute of Technology

SiC foam ceramic reinforced aluminum matrix composites(SfCAMCs)were prepared by squeeze casting aluminum alloy(Al-23Si)into the SiC foam ceramic with different pore sizes,and the corrosion behavior of the SfCAMCs was studied in NaCl *** immersion corrosion tests were conducted at 20°C,50°C and 80°C,*** morphology and products were analyzed by scanning electron microscope,energy dispersive system and X-ray *** was found that the corrosion rate of SfCAMCs increases as the temperature rising,and the bigger pore size of SiC foam ceramic reinforcement,the better corrosion resistance of SfCAMCs.

关键词： SiC ceramic foam aluminum matrix composites corrosion NaCl

Color tunable upconversion emission in Ceo_2:Yb,Er three-dimensional ordered macroporous materials

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Journal of Rare Earths 2015年第6期33卷 599-603页

作者：程彦敏杨正文廖佳燕邱建备宋志国杨勇 College of Materials Science and engineering Kunming University of Science and Technology

The three-dimensional ordered macroporous Ceo2：Yb,Er materials were prepared, and the influence of doping concentra- tion of Yb3＋ or Er3＋ ions on upconversion property was investigated. Green and red upconversion emissions were observed under the excitation of 980 nm at room temperature. It was found that the ratio of red to green upconversion emission intensity increased with increasing of concentration of the Yb3＋ or Er3＋ ions in the three-dimensional ordered macroporous Ceo2：Yb,Er materials. When the concentration of Yb3＋ was 10 mol%, pure red upconversion emission was obtained. The varied mechanism of ratio of red to green upconversion emission intensity was discussed with the concentration of Yb3＋ or Er3＋ ions.

关键词： three-dimensional ordered macroporous materials Ceo2:Yb,Er upconversion emission color tunability rare earths

Effects of lanthanum on hot deformation behaviour of Mn-Cr-Mo bainitic rail steel

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Journal of Rare Earths 2018年第7期36卷 772-780页

作者： Xirong Bao Jun'an Wang Xiaodong Wang feng Guo Yongzhen Liu Institute of Materials School of Materials Science and EngineeringShanghai University School of Material and Metallurgy Inner Mongolia University of Science and Technology School of Materials Science and engineering Inner Mongolia University of Technology School of Mining and Coal Inner Mongolia University of Science and Technology

Effects of lanthanum（La） as micro-alloying element on the hot deformation behaviour of the high strength Mn-Cr-Mo bainitic rail steel were investigated under a range of deformation conditions. The results indicate that La increases the flow stress by 10-30 MPa through strengthening nanoscale strain induced precipitation（SIP） θ-（fe,La）3 C during hot deformation. The hot deformation activation energy increases by 10-40 kJ/mol due to the ＂Zener effect＂ of SIP and the dynamic recrystallization（DRX） is retarded due to the competitive behaviour between SIP and DRX. Bainite plates in the DRX domain can be refined by adding La, resulting in the improvement of hot workability. The DRX domain with peak power dissipation efficiency of 52% is determined to be the optimal processing region for Mn-Cr-Mo-La bainitic rail steel.

关键词： Rare earth Hot deformation Strain induced precipitation Dynamic recrystallization Dissipation map Microstructure

Numerical study on similarity of plume infrared radiation between reduced-scale solid rocket motors

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Chinese Journal of Aeronautics 2016年第4期29卷 924-933页

作者： Zhang Xiaoying Chen Huandong Sino-french Institute of Nuclear engineering and technology Sun Yat-sen University School of Electricity South China University of Technology

This study seeks to determine the similarities in plume radiation between reduced and full-scale solid rocket models in ground test conditions through investigation of flow and radiation for a series of scale ratios ranging from 0.1 to 1. The radiative transfer equation (RTE) considering gas and particle radiation in a non-uniform plume has been adopted and solved by the finite volume method (fVM) to compute the three dimensional, spectral and directional radiation of a plume in the infrared waveband 2-6 mu m. Conditions at wavelengths 2.7 mu m and 4.3 mu m are discussed in detail, and ratios of plume radiation for reduced-scale through full-scale models are examined. This work shows that, with increasing scale ratio of a computed rocket motor, area of the high-temperature core increases as a 2 power function of the scale ratio, and the radiation intensity of the plume increases with 2-2.5 power of the scale ratio. The infrared radiation of plume gases shows a strong spectral dependency, while that of Al2o3 particles shows spectral continuity of gray media. Spectral radiation intensity of a computed solid rocket plume's high temperature core increases significantly in peak radiation spectra of plume gases Co and Co2 center dot Al2o3 particles are the major radiation component in a rocket plume. There is good similarity between contours of plume spectral radiance from different scale models of computed rockets, and there are two peak spectra of radiation intensity at wavebands 2.7-3.0 lm and 4.2-4.6 lm. Directed radiation intensity of the entire plume volume will rise with increasing elevation angle. (C) 2016 Chinese Society of Aeronautics and Astronautics. Production and hosting by Elsevier Ltd.

关键词： Infrared radiation Plume Reduced-scale model Similarity Solid rocket motor

A new framework for evaluating along-wind responses of a transmission tower

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Earthquake engineering and engineering Vibration 2009年第1期8卷 87-93页

作者： Liu Guohuan and Li Hongnan School of Civil and Hydraulic engineering, Dalian university of technology, Dalian 116023, China PhD Professor School of Civil and Hydraulic engineering Dalian University of Technology Dalian China

In this paper, an analytical framework to evaluate the along-wind-induced dynamic responses of a transmission tower is presented. Two analytical models and a new method are developed：（1） a higher mode generalized force spectrum （GfS） model of the transmission tower is deduced; （2） an analytical model that includes the contributions of the higher modes is further derived as a rational algebraic formula to estimate the structural displacement response; and （3） a new approach, applying load with displacement （ALD） instead of force, to solve the internal force of transmission tower is given. Unlike conventional methods, the ALD method can avoid calculating equivalent static wind loads （ESWLs）. finally, a transmission tower structure is used as a numerical example to verify the feasibility and accuracy of the ALD method.

关键词： along-wind-induced dynamic responses transmission tower generalized force spectrum equivalent static wind loads

Assessment of Elasticity,Plasticity and Resistance to Machining-induced Damage of Porous Pre-sintered Zirconia Using Nanoindentation Techniques

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Journal of Materials Science & technology 2016年第5期32卷 402-410页

作者： Abdur-Rasheed Alao Ling Yin Matter & Materials College of Science Technology & Engineering James Cook University

Porous pre-sintered zirconia is subject to white machining during which its elasticity, plasticity and resistance to machining-induced damage determine its machinability and final quality. This study used nanoindentation techniques and the Sakai＇s series elastic and plastic deformation model to extract the resistance to plastic deformation from the plane strain modulus and the contact hardness for presintered zirconia. The modulus and the resistance to plasticity were used to calculate the relative amount of elasticity and plasticity. The fracture energy and the normalized indentation absorbed energy were used to deconvolute the resistance to machining-induced cracking based on the Sakai-Nowak model. All properties were extracted at a 10 mN peak load and loading rates of 0.1-2 mN/s to determine the loading rate effects on these properties. We found that the resistance to plasticity and the resistance to machining-induced cracking were independent of the loading rate （ANoVA, p 〉 0.05）. The elastic and plastic displacements depended on the loading rate through power laws. This loading rate-dependent deformation behaviour was explained by the maximum shear stress generated underneath the indenter and the indentation energy. The plastic deformation components and the indentation absorbed energy at all loading rates were higher than the elastic deformation components and the elastic strain energy, respectively. finally, we established the linkage among the pore structure, indentation behaviour and machinability of pre-sintered zirconia.

关键词： Elastic/plastic deformation Loading rate Nanoindentation Pre-sintered zirconia Resistance to machining-induced cracking Resistance to plasticity

Synergistic effect of hybrid Himalayan Nettle/Bauhinia-vahlii fibers on physico-mechanical and sliding wear properties of epoxy composites

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Defence technology（防务技术） 2020年第4期16卷 762-776页

作者： Sandeep Kumar KKSMer Brijesh Gangil Vinay Kumar Patel Department of Mechanical engineering S.O.E.T.H.N.B.Garhwal UniversitySrinagar-Garhwal246174UttarakhandIndia Department of Mechanical engineering Govind Ballabh Pant Institute of Engineering and Technology GhurdauriPauri Garhwal246001UttarakhandIndia

The cellulosic bast fibers are recognized as a justifiable and biodegradable substitute for producing moderate strength polymer composite materials because of their characteristics of renewability,ecofriendliness,and higher specific *** the aim of this research work is to fabricate Himalayan bast fibers(Nettle fiber(Nf)/bauhinia vahlii fiber(Bf)) based mono/hybrid epoxy composites at varying weight percentage of 2-6 wt% and evaluate the physical(void fraction and water absorption),mechanical(tensile strength,flexural strength,hardness) and sliding wear properties of as-fabricated *** 6 wt% NBf reinforced composites exhibited higher mechanical properties as compared to Nf and Bf composites with tensile strength of 34.04 MPa,flexural strength of 42.45 MPa,and hardness of 37.01 Hv *** influence of various control factors(sliding velocity,Nf/Bf/NBf contents,normal load and sliding distance) on specific sliding wear rate of composites was evaluated by Taguchi(three factors at three levels) experimental design and the percentage contribution of these selected parameters on sliding wear performance was examined by Analysis of variance(ANoVA).The sliding wear property of as-developed composites was found to be greatly influenced by sliding velocity and the wear resistance was observed to be improved with the Nf/Bf/NBf *** wear mechanism of the as-fabricated composites has been elucidated by scanning electron microscopy *** research outcomes demonstrated that the hybridization of Bauhinia vahlii fiber with Nettle fiber led to improve the mechanical and wear properties of epoxy composites.

关键词： Natural fiber Physical properties Mechanical properties Wear properties Taguchi analysis

Inhibition of La-fe-Co-Si compound corrosion in distilled water by sodium molybdate and disodium hydrogen phosphate

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Journal of Rare Earths 2011年第2期29卷 138-142页

作者：张敏叶荣昌龙毅常永勤 School of Materials Science and engineering University of Science and Technology Beijing

A comparative study of Na2Moo4·2H2o and Na2HPo4·12H2o as inhibitors for magnetic refrigeration material La-fe-Co-Si compound corrosion in distilled water at room temperature was carried ***,the inhibiting behavior of the mixture of Na2Moo4·2H2o and Na2HPo4·12H2o was *** polarization curves and electrochemical impedance spectroscopy （EIS） measurements were applied to study the corrosion behavior of the compound in the absence or presence of different concentrations of these inhibitors under the same experimental *** study revealed that the mixture of 3.0×10–3 kg/L Na2Moo4·2H2o and 5.0×10–3 kg/L Na2HPo4·12H2o was the best inhibitor reaching the value of inhibition efficiency （ε%） up to 93.9%.Polarization curves showed that the studied compounds acted as anodic *** potential of zero charge （PZC） of La-fe-Co-Si compound was determined in distilled water in the absence of the studied *** inhibition mechanisms for inhibitors were proposed in this work.

关键词： magnetic refrigeration material La-fe-Co-Si compound inhibitor Na2Moo4·2H2o Na2HPo4·12H2o

Effect of Ceo_2 and Cao Promoters on Ignition Performance for Partial oxidation of Methane over Ni/Mgo-Al_2o_3 Catalyst

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Journal of Natural Gas Chemistry 2007年第2期16卷 148-154页

作者： Yejun Qiu Jixiang Chen Jiyan Zhang Department of Catalysis Science and engineering School of Chemical Engineering and Technology Tianjin University Tianjin 300072 China

The effect of Ceo2 and Cao promoters on the ignition performance over Ni/Mgo-Al2o3 catalyst for the partial oxidation of methane （PoM） to synthesis gas was investigated. It was found that the PoM reaction could not be ignited over lwt%Ni/Mgo-Al2o3 catalyst without the promoters in the temperature range from 773 K to 1073 K. Ceo2 and Cao promoters enhanced the ignition performance and the PoM reactivity of lwt%Ni/Mgo-Al2o3 catalyst remarkably. Moreover, the improving effect became greater with the increase of the promoter content under the investigated reactiorrconditions. The modification effects of Ceo2 and Cao promoters were closely related to the concentration and reducibility of the surface and bulk oxygen species.

关键词： partial oxidation of methane synthesis gas nickel-based catalyst ignition cerium oxide calcium oxide