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Physical properties of B4N4-Ⅰ and B4N4-Ⅱ:First-principles study
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作者 马振洋 王鹏 +2 位作者 阎芳 史春蕾 田毅 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第3期283-290,共8页
The structural, mechanical, electronic, mechanical anisotropy, and thermal properties of boron nitride(BN) polymorphs, such as B4 N-4-Ⅰ and B4 N4-Ⅱ, are investigated under ambient pressure utilizing first-principles... The structural, mechanical, electronic, mechanical anisotropy, and thermal properties of boron nitride(BN) polymorphs, such as B4 N-4-Ⅰ and B4 N4-Ⅱ, are investigated under ambient pressure utilizing first-principles generalized gradient approximation calculations using an ultrasoft pseudopotential scheme. The phonon spectra and elastic constants reveal that B4 N4-Ⅰ is dynamically and mechanically stable at the pressure of 0 GPa and temperature of 0 K. Anisotropic calculations indicate that both B4 N4-Ⅰ and B4 N4-Ⅱ exhibit higher anisotropy of Young’s modulus than cubic BN(c-BN). B4 N4-Ⅱ and B4 N4-Ⅰ present indirect and wide band gaps of 5.32 eV and 4.86 eV, respectively. In addition, B4 N4-Ⅰ is more brittle than B4 N4-Ⅱ. Moreover, the minimum thermal conductivity,κmin, of B4 N4-Ⅱ at 300 K is 1.92 W/(cm·K), which is slightly higher than those of B4 N4-Ⅰ and c-BN(1.84 W/(cm-K) and 1.83 W/(cm-K), respectively. However, κmin of B4 N4-Ⅰ is slightly higher than that of c-BN. 展开更多
关键词 BN POLYMORPHS MECHANICAL PROPERTIES electronic PROPERTIES MECHANICAL ANISOTROPIC PROPERTIES
Growth behavior and electronic properties of Gen+1 and AsGen(n = 1–20) clusters: a DFT study 预览
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作者 M.Benaida K.E.Aiadi +3 位作者 S.Mahtout S.Djaadi W.Rammal M.Harb 《半导体学报:英文版》 EI CAS CSCD 2019年第3期9-17,共9页
We present a systematic computational study based on the density functional theory(DFT) aiming to high light the possible effects of one As doping atom on the structural, energetic, and electronic properties of differ... We present a systematic computational study based on the density functional theory(DFT) aiming to high light the possible effects of one As doping atom on the structural, energetic, and electronic properties of different isomers of Gen+1 clusters with n = 1–20 atoms. By considering a large number of structures for each cluster size, the lowest-energy isomers are determined. The lowest-energy isomers reveal three-dimensional structures starting from n = 5. Their relative stability versus atomic size is examined based on the calculated binding energy, fragmentation energy, and second-order difference of energy. Doping Gen+1 clusters with one As atom does not improve their stability. The electronic properties as a function of the atomic size are also discussed from the calculated HOMO–LUMO energy gap, vertical ionization potential, vertical electron affinity, and chemical hardness. The obtained results are significantly affected by the inclusion of one As atom into a Gen cluster. 展开更多
关键词 DENSITY FUNCTIONAL theory As–Ge CLUSTERS structural PROPERTIES ELECTRONIC PROPERTIES
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Effect of retained austenite and nonmetallic inclusions on the thermal/electrical properties and resistance spot welding nuggets of Si-containing TRIP steels 预览
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作者 V.H.Vargas I.Mejía +1 位作者 V.H.Baltazar-Hernández C.Maldonado 《矿物冶金与材料学报:英文版》 SCIE EI CAS CSCD 2019年第1期52-63,共12页
Five advanced high-strength transformation-induced plasticity(TRIP)steels with different chemical compositions were studied to correlate the retained austenite and nonmetallic inclusion content with their physical pro... Five advanced high-strength transformation-induced plasticity(TRIP)steels with different chemical compositions were studied to correlate the retained austenite and nonmetallic inclusion content with their physical properties and the characteristics of the resistance spot welding nuggets.Electrical and thermal properties and equilibrium phases of TRIP steels were predicted using the JMatPro software.Retained austenite and nonmetallic inclusions were quantified by X-ray diffraction and saturation magnetization techniques.The nonmetallic inclusions were characterized by scanning electron microscopy.The results show that the contents of Si,C,Al,and Mn in TRIP steels increase both the retained austenite and the nonmetallic inclusion contents.We found that nonmetallic inclusions affect the thermal and electrical properties of the TRIP steels and that the differences between these properties tend to result in different cooling rates during the welding process.The results are discussed in terms of the electrical and thermal properties determined from the chemical composition and their impact on the resistance spot welding nuggets. 展开更多
关键词 transformation-induced plasticity steel retained austenite non-metallic inclusions magnetic saturation electrical PROPERTIES THERMAL PROPERTIES resistance spot welding NUGGET
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Structural Stability, Electronic and Magnetic Properties of O-doped Monolayer C2N 预览
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作者 陈颖 刘光华 +2 位作者 李逸鹏 孔龙娟 刘鹏飞 《结构化学》 SCIE CAS CSCD 2019年第1期76-82,3共8页
Based on the first-principles of density functional theory, the structural stability,electronic and magnetic properties of the O-doped monolayer C2N are investigated. In details, the lattice parameters, band structure... Based on the first-principles of density functional theory, the structural stability,electronic and magnetic properties of the O-doped monolayer C2N are investigated. In details, the lattice parameters, band structures, density of states and phonon dispersions of O-doped monolayer C2N are obtained and analyzed. Our results show that the introduction of oxygen dopants can cause a significant local lattice distortion. The band structure indicates that monolayer C2N is a semiconductor with a direct band gap of 1.631 eV. The electronic properties of monolayer C2N can be regulated by oxygen dopant atoms with different numbers. However, doping nonmetal oxygen element in monolayer C2N does not affect its magnetic properties. In other words, the pure and O-doped systems are all nonmagnetic. The phonon dispersions of all the O-doped cases are found to have not any imaginary frequencies, which indicates that the structures of these O-doped systems have good structural stability. 展开更多
关键词 O-doping electronic PROPERTIES magnetic PROPERTIES STRUCTURAL stability
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Enhanced mechanical and thermal properties of γ-allyloxymethyl 18-crown-6 and polyimide composites through hydrosilylation crosslinking
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作者 Chuqi Shi Shumei Liu +2 位作者 Yang Li Jianqing Zhao Haohao Huang 《中国化学快报:英文版》 SCIE CAS CSCD 2019年第3期710-713,共4页
The complexation of y-allyloxymethyl 18-crown-6(AC6) induced inferior mechanical and thermal properties of polyimide(PI) in spite of lowered dielectric constant(k). To solve this puzzle, tetrakis-(di methylsiloxy)-si ... The complexation of y-allyloxymethyl 18-crown-6(AC6) induced inferior mechanical and thermal properties of polyimide(PI) in spite of lowered dielectric constant(k). To solve this puzzle, tetrakis-(di methylsiloxy)-si lane was employed to crosslink the complex of AC6 and PI(AC6-PI) through hydrosilylation reaction. The crosslinked AC6-PI(SiAC-PI) composites possessed excellent mechanical and thermal properties as well as low k. The tensile strength and fracture energy of SiAC-PI were increased by 87% and 716%, and the glass transition temperature and 5% weight loss temperature elevated 14.5 ℃ and 38.8 ℃, respectively, compared with those of AC6-PI. The structure of SiAC-PI was characterized by FTIR spectra, crosslinked density and XRD diffraction patterns. 展开更多
关键词 POLYMERIC COMPOSITES Dielectrics Mechanical PROPERTIES Thermal PROPERTIES HYDROSILYLATION CROSSLINKING
Wear behavior of light-weight and high strength Fe-Mn-Ni-Al matrix self-lubricating steels
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作者 Liuliu Han Kun Li +3 位作者 Cheng Qian Jingwen Qiu Chengshang Zhou Yong Liu 《材料科学技术学报:英文版》 SCIE EI CAS CSCD 2019年第4期623-630,共8页
The good combination of mechanical and tribological properties for self-lubricating materials is crucial. In this work, novel self-lubricating Fe-16.4 Mn-4.8 Ni-9.9 Al-xC(wt%) steels containing graphite phase were fab... The good combination of mechanical and tribological properties for self-lubricating materials is crucial. In this work, novel self-lubricating Fe-16.4 Mn-4.8 Ni-9.9 Al-xC(wt%) steels containing graphite phase were fabricated using mechanical alloying and spark plasma sintering. The compositions of the steels were designed by using thermodynamic calculation, and the effect of carbon addition on the microstructure was further investigated. The steel possesses high hardness of 621 HV, high yield strength of 1437 MPa and good fracture toughness at room temperature. The yield strengths are still above 600 MPa at 600?C.The tribological behavior and mechanical properties from room temperature to 800?C were studied, and the wear mechanisms at elevated temperatures were discussed. The steel has a stable friction coefficient of 0.4 and wear rate in a magnitude of 10-6 mm3/N·m below 600?C. The good tribological properties of the steels were mainly attributed to the high hardness, lubrication of graphite and stable surface oxide layer. 展开更多
关键词 Metal MATRIX composites MECHANICAL alloying MECHANICAL PROPERTIES TRIBOLOGICAL PROPERTIES Alloy design
Supercritical CO2:Properties and Technological Applications-A Review
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作者 NIKOLAI Polikhronidi RABIYAT Batyrova +1 位作者 ASLAN Aliev ILMUTDIN Abdulagatov 《热科学学报:英文版》 SCIE EI CAS CSCD 2019年第3期394-430,共37页
The main goal of the present paper is to assess the available information so as to obtain a general procedure for dealing with the critical enhancement of the thermodynamic and transport properties of supercritical CO... The main goal of the present paper is to assess the available information so as to obtain a general procedure for dealing with the critical enhancement of the thermodynamic and transport properties of supercritical CO2 and CO2 containing binary mixtures for practical and scientific applications.The present review provides comprehensive analysis of the thermodynamic and transport properties of supercritical carbon dioxide and CO2 containing binary mixtures(experiment and theory)and their various technological and scientific applications in different natural and industrial processes.The available information for the thermodynamic and transport properties(experiment and theory)enhancement(anomaly)of supercritical carbon dioxide and SC CO2+solute mixtures is comprehensively reviewed.The effect of long-range order parameter fluctuations on the thermodynamic and transport properties of supercritical fluids(SC CO2)will be discussed.Simplified scaling type equation based on mode-coupling theory of critical dynamics with two critical amplitudes and one cutoff wave number as fluid-specific parameters was used to accurately predict of the transport properties of supercritical carbon dioxide.The recommended values of the specific parameters(asymptotic critical amplitudes)of the carbon dioxide for practical(prediction of the thermodynamic and transport properties of the supercritical CO2 for technological applications)and scientific use were provided.The role of the critical line shapes of the carbon dioxide containing binary mixture(SC CO2+solvent)in determination of the critical behavior of the mixture near the critical point of pure supercritical solvent(CO2)is discussed.Krichevskii parameter concept for a description of thermodynamic behavior of dilute near-critical SC CO2+solute mixtures is also discussed.The structural and thermodynamic properties of the carbon dioxide containing binary mixtures near the critical point of pure solvent(CO2)are discussed. 展开更多
关键词 carbon dioxide CRITICAL point EQUATION of state SUPERCRITICAL FLUID THERMODYNAMIC PROPERTIES transport PROPERTIES
Spectra properties of Yb3+,Er3+:Sc2SiO5 crystal
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作者 薛艳艳 郑丽和 +3 位作者 姜大朋 赛青林 苏良碧 徐军 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第3期362-365,共4页
The influence of Er3+ ions on the spectra of Yb3+,Er3+: Sc2 SiO5(SSO) single crystal, which was obtained by Czochralski(Cz) method, is discussed. The absorption coefficient at 980 nm was 13.36 cm-1 with a peak absorpt... The influence of Er3+ ions on the spectra of Yb3+,Er3+: Sc2 SiO5(SSO) single crystal, which was obtained by Czochralski(Cz) method, is discussed. The absorption coefficient at 980 nm was 13.36 cm-1 with a peak absorption cross-section of 1.46 × 10-20 cm2. The emission cross-sections at 1034 nm and 1062 nm were 5.5 × 10-21 cm2 and4.9 × 10-21 cm2, respectively. The fluorescence lifetime was estimated as 1.24 ms at 1061 nm. The mechanical properties of SSO single crystal were also presented. 展开更多
关键词 YB3+ Er3+: Sc2SiO5 SPECTRA PROPERTIES MECHANICAL PROPERTIES
Potential Use of a Poultry Manure Digestate as a Biofertiliser:Evaluation of Soil Properties and Lactuca sativa Growth
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作者 Natalia MóRTOLA Romina ROMANIUK +9 位作者 Vanina COSENTINO Maximiliano EIZA Patricia CARFAGNO Pedro RIZZO Patricia BRES Nicolás RIERA Marcos ROBA Mariano BUTTI Daiana SAINZ Lucrecia BRUTTI 《土壤圈:英文版》 SCIE CAS CSCD 2019年第1期60-69,共10页
Anaerobic digestion is a process that is widely used for the treatment of organic wastes. The digestate can be used as a soil amendment or crop fertiliser. The aims of our work were to evaluate 1) the physicochemical ... Anaerobic digestion is a process that is widely used for the treatment of organic wastes. The digestate can be used as a soil amendment or crop fertiliser. The aims of our work were to evaluate 1) the physicochemical composition and pathogen content in a digestate from poultry manure, according to international regulations, and 2) the effect of its soil application on the major chemical and biological soil properties and on the growth of Lactuca sativa. The experiment consisted of two groups of pots(with and without crop). Treatments applied to each group were as follows: low and high doses of digestate and inorganic fertiliser, and no application(control)(low dose: 70 kg nitrogen(N) ha-1 and 21 kg phosphorus(P) ha-1;high dose: 210 kg N ha-1 and 63 kg P ha-1). Soil samples were taken 7 and 34 d(harvest) after treatment applications. Heavy metal and pathogen contents in the digestate were below the upper limit values. Despite the high pH and electrical conductivity values of the digestate, both soil parameters presented acceptable values for crop growth. Although there were no initial increases in total inorganic N and available P in soil with digestate application, an increase in the fresh weight of crop was observed with the high dose application. This is probably associated with the slow nutrient release from the digestate during the development of the crop. Changes in the microbial community were temporary and occurred at the initial sampling stage of the experiment. 展开更多
关键词 anaerobic digestion crop yield ORGANIC FERTILISER ORGANIC waste SOIL amendment SOIL chemical PROPERTIES SOIL microbiological PROPERTIES
Change in Surface Microstructure and Properties of PTFE after Solar Radiation and its Mechanism
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作者 马国政 DING Guangyu +3 位作者 LIU Xuebin 王海斗 ZHAI Huanchun ZHU Hui 《武汉理工大学学报:材料科学英文版》 SCIE EI CAS 2019年第1期223-229,共7页
A series of solar radiation tests for the polytetrafluoroethylene(PTFE) bulk and film samples were carried out using Q-SUN XE-3-HSC type Solar Radiation Simulator, with the test parameters as follows: radiation intens... A series of solar radiation tests for the polytetrafluoroethylene(PTFE) bulk and film samples were carried out using Q-SUN XE-3-HSC type Solar Radiation Simulator, with the test parameters as follows: radiation intensity is 1 120 W/m~2, temperature is 55 ℃ and humidity is 70% RH. Surface morphology, composition and microstructure of the PTFE samples before and after radiation tests were characterized contrastively. Effect of solar radiation on the tribology and wetting properties of PTFE were also studied by tribometer and contact angle tester, respectively. The results show that, for radiated PTFE, surface roughness, the relative content of C element, the friction coefficients and the contact angle with water increased in varying degrees. In conclusion, the obvious change in PTFE samples can be mainly attributed to break of(CFx)-C bonds after bombardment of high energy UV photons, which causes the loss of F-rich groups, oxidation, crosslinking and restructuring of active unsaturated groups. 展开更多
关键词 SOLAR radiation PTFE microstructure TRIBOLOGICAL PROPERTIES WETTING PROPERTIES
Effect of Electron Beam Irradiation on Thermal and Mechanical Properties of Polyamide Copolymer/Multiwall Carbon Nanotube Composites
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作者 崔成文 陈禹廷 张勇 《上海交通大学学报:英文版》 EI 2019年第1期12-18,共7页
Ternary polyamide(tPA) copolymer is susceptible to degradation when it is irradiated by electron beam(e-beam), and effective methods to avoid degradation and increase gel content are highly desirable for crosslinking.... Ternary polyamide(tPA) copolymer is susceptible to degradation when it is irradiated by electron beam(e-beam), and effective methods to avoid degradation and increase gel content are highly desirable for crosslinking.Carboxylated multiwall carbon nanotube(MWCNT) is modified by hydroxyethyl acrylate(HEA) in this paper and used as a co-agent for the e-beam irradiation crosslinking of tPA copolymer. HEA modified MWCNT can function as an effective co-agent for the e-beam irradiation crosslinking of tPA copolymer to increase the gel content and improve the mechanical properties of tPA copolymer. Under an irradiation of 160 kGy, addition of 2 parts per hundred(phr) HEA modified MWCNT into tPA copolymer can increase the gel content of tPA copolymer from about 20% to 40%(mass ratio) and increase the tensile strength from 45 to 59 MPa. The irradiation also affects the glass transition temperature of tPA copolymer by increasing the gel content. The results show that HEA modified MWCNT can act as a nucleating agent to increase the crystallization temperature, melting temperature and crystallinity of tPA copolymer. 展开更多
关键词 electron beam(e-beam) irradiation ternary polyamide(tPA) COPOLYMER multiwall carbon nanotube(MWCNT) mechanical PROPERTIES thermal PROPERTIES
Improved tabledng behavior of paracetamol in the presence of polyvinylpyrrolidone additive: Effect of mixing conditions
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作者 Ayuk Agbor Rose Waseem Kaialy 《中国颗粒学报:英文版》 SCIE EI CAS CSCD 2019年第2期9-18,共10页
Monoclinic paracetamol (PA) is notorious as a poorly compactible model drug. Polyvinylpyrrolidone (PVP) is a polymer that can act as an effective binder to improve the mechanical properties of PA. It is surprising how... Monoclinic paracetamol (PA) is notorious as a poorly compactible model drug. Polyvinylpyrrolidone (PVP) is a polymer that can act as an effective binder to improve the mechanical properties of PA. It is surprising however that the role of mixing conditions on the physicochemical and mechanical properties of PA-PVP mixtures has not been reported previously. The results of this work showed that PA-PVP mixtures containing 5%(w/w) PVP prepared using high energy mixing conditions had considerably smaller particle size distributions and higher cohesivities than mixtures prepared using low energy mixing conditions. Solid-state analysis did not detect any change in the monoclinic crystalline form of PA after mixing with PVP. The following rank order of tabletability for PA-PVP mixtures was obtained according to the mixing condition: low shear-medium shear< dry high shear< wet high shear< high-speed homogenization. A higher level of hydrogen bonding was detected in the mixtures prepared via high energy mixing conditions than in those prepared using low energy mixing conditions. Mixing is therefore a critical process that needs to be optimized during the preparation of in teractive mixtures for tableting. 展开更多
关键词 Direct compression INTERACTIVE mixtures Hydrogen bonding Mechanical PROPERTIES PHYSICOCHEMICAL PROPERTIES Tableting
Effect of Ca on microstructure and high temperature creep properties of AM60-1Ce alloy
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作者 Wei Jin Yu-lai Song +2 位作者 Yao-hui Liu Ping Zhao R. D. K. Misra 《中国铸造:英文版》 SCIE 2019年第2期88-96,共9页
A series of AM60-1Ce-xCa(x=0, 0.5, 1.5, 2.5) magnesium alloys were prepared by gravity casting method and analyzed by means of XRD, DSC and SEM. The effects of Ca on normal temperature mechanical properties and high t... A series of AM60-1Ce-xCa(x=0, 0.5, 1.5, 2.5) magnesium alloys were prepared by gravity casting method and analyzed by means of XRD, DSC and SEM. The effects of Ca on normal temperature mechanical properties and high temperature creep behavior of alloys were characterized by tensile and constant creep test.Microstructure analysis indicated that Ca was preferentially combined with Al in the alloy to form the high melting point Al2Ca phase at the grain boundary. The addition of Ca can refine the crystal grains and reduces the content of β-Mg17Al12 phase. With the increase of Ca content in the alloy, Al2Ca phases at the grain boundary gradually changed to the network of lamellar structure, and replaced the β-Mg17Al12 phase as the main strengthening phase gradually. The creep resistance of the alloy continuously increases because the high-temperature stable phase Al2Ca firmly nailed at grain boundaries impedes the sliding of grain boundaries. However, when the addition of Ca was more than 1.5%, mechanical properties of the alloy started to decrease, which was probably due to the large amount of irregularly shaped Al2Ca phases at the grain boundary. Experimental results show that the optimal addition amount of Ca is 1.5 wt.%. 展开更多
关键词 AS-CAST magnesium ALLOY Al2Ca HARD phase mechanical PROPERTIES high temperature CREEP PROPERTIES
Modification of Oil Palm Empty Fruit Bunch and Sugarcane Bagasse Biomass as Potential Reinforcement for Composites Panel and Thermal Insulation Materials
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作者 Nor Azlina Ramlee Mohammad Jawaid +1 位作者 Edi Syams Zainudin Shaikh Abdul Karim Yamani 《仿生工程学报:英文版》 SCIE EI CSCD 2019年第1期175-188,共14页
This paper focuses on the study of the effect of modification of Oil Palm Empty Fruit Bunch(OPEFB)and sugarcane bagasse(SCB)biomass as potential reinforcement for composites panel and thermal insulation.Both fibres we... This paper focuses on the study of the effect of modification of Oil Palm Empty Fruit Bunch(OPEFB)and sugarcane bagasse(SCB)biomass as potential reinforcement for composites panel and thermal insulation.Both fibres were treated with three types of chemicals:2%silane,4%H2O2 and 4%H2O2-2%silane for 3 h.The influence of modified fibres content in composites was examined by structural changes using image analyser,Fourier transform infrared(FTIR),Scanning Electron Microscopy(SEM),tensile,interracial shear strength(IFSS)and thermal characteristic.The diameter of both fibres was reduced after treatment and showed decreasing of lignin and hemi-cellulose in fibre.Tensile strength has been increased by 2%silane treatment for both fibres and 4%H2O2 treatment displays higher result for IFSS.Thermal properties of treated SCB fibre with silane display higher residual content and better thermal stability.SEM charac-terization showed that 2%silane treatment removed silica bodies of OPEFB fibre while 4%H2O2 treatment uniformly filled porosity of SCB fibre.Finally,results revealed that treated OPEFB fibre is enough to improve compatibility and mechanical properties,while treated SCB fibre was effective in thermal stability for fabrication of composite materials. 展开更多
关键词 oil palm EMPTY fruit BUNCH SUGARCANE BAGASSE fibre treatment tensile PROPERTIES thermal PROPERTIES INTERRACIAL shear strength
A flexible conductive hybrid elastomer for high-precision stress/strain and humidity detection
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作者 Haoran Liu Zhenyi Zhang +4 位作者 Jun Ge Xiao Lin Xinye Ni Huilin Yang Lei Yang 《材料科学技术学报:英文版》 SCIE EI CAS CSCD 2019年第1期176-180,共5页
Flexible and environment-responsive materials are essential for a large number of applications from artificial skin to wearable devices. The present study develops a flexible, ultra-low cost conductive hybrid elastome... Flexible and environment-responsive materials are essential for a large number of applications from artificial skin to wearable devices. The present study develops a flexible, ultra-low cost conductive hybrid elastomer(CHE), which possesses high responsive capabilities to stress/strain and humidity. CHE was composed of polydimethylsiloxane(PDMS) and starch hydrogel(SH), enabling great elasticity(56 kPa),high conductivity(10^-2S/m) and high sensitivity to external stimuli(gauge factor of CHE under stress and strain are 0.71 and 2.22, respectively, and sensitivity to humidity is 1.2 × 10^-6S/m per RH%). These properties render CHE a promising candidate for artificial skin and wearable electronics applications of continuously monitoring environmental information. 展开更多
关键词 CONDUCTIVE composites Electrical PROPERTIES Mechanical PROPERTIES MOISTURE HYBRID ELASTOMER
Grain boundary and microstructure engineering of Inconel 690 cladding on stainless-steel 316L using electron-beam powder bed fusion additive manufacturing
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作者 I.A. Segura L.E. Murr +7 位作者 C.A. Terrazas D. Bermudez J. Mireles V.S.V. Injeti K. Li B. Yu R.D.K.Misra R.B. Wicker 《材料科学技术学报:英文版》 SCIE EI CAS CSCD 2019年第2期351-367,共17页
This research explores the prospect of fabricating a face-centered cubic(fcc) Ni-base alloy cladding(Inconel 690) on an fcc Fe-base alloy(316 L stainless-steel) having improved mechanical properties and reduced sensit... This research explores the prospect of fabricating a face-centered cubic(fcc) Ni-base alloy cladding(Inconel 690) on an fcc Fe-base alloy(316 L stainless-steel) having improved mechanical properties and reduced sensitivity to corrosion through grain boundary and microstructure engineering concepts enabled by additive manufacturing(AM) utilizing electron-beam powder bed fusion(EPBF). The unique solidification and associated constitutional supercooling phenomena characteristic of EPBF promotes[100] textured and extended columnar grains having lower energy grain boundaries as opposed to random, high-angle grain boundaries, but no coherent {111} twin boundaries characteristic of conventional thermo-mechanically processed fcc metals and alloys, including Inconel 690 and 316 L stainless-steel.In addition to [100] textured grains, columnar grains were produced by EPBF fabrication of Inconel 690 claddings on 316 L stainless-steel substrates. Also, irregular 2–3 μm diameter, low energy subgrains were formed along with dislocation densities varying from 108 to 109 cm2, and a homogeneous distribution of Cr23C6 precipitates. Precipitates were formed within the grains(with 3 μm interparticle spacing),but not in the subgrain or columnar grain boundaries. These inclusive, hierarchical microstructures produced a tensile yield strength of 0.527 GPa, elongation of 21%, and Vickers microindentation hardness of 2.33 GPa for the Inconel 690 cladding in contrast to a tensile yield strength of 0.327 GPa, elongation of 53%, and Vickers microindentation hardness of 1.78 GPa, respectively for the wrought 316 L stainlesssteel substrate. Aging of both the Inconel 690 cladding and the 316 L stainless-steel substrate at 685?C for50 h precipitated Cr23C6 carbides in the Inconel 690 columnar grain boundaries, but not in the low-angle(and low energy) subgrain boundaries. In contrast, Cr23C6 carbides precipitated in the 316 L stainless-steel grain boundaries, but not in the low energy coherent {111} twin boundaries. Consequently, the Inconel6 展开更多
关键词 Additive manufacturing ELECTRON-BEAM powder bed FUSION (EPBF) INCONEL 690 CLADDING 316L stainless steel Grain boundary engineering Materials characterization Mechanical properties
CPE改性硬质PVC增韧效果的研究 预览
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作者 冯光峰 樊陈莉 +1 位作者 洪娟 刘孝阳 《现代塑料加工应用》 CAS 北大核心 2019年第1期18-21,共4页
通过不同结构特征的高密度聚乙烯(HDPE)氯化反应后制得氯化聚乙烯(CPE),研究了CPE改性硬质聚氯乙烯(PVC-U)制品的力学性能;同时也探究了不同相对分子质量特征和部分接枝易于塑化链段的HDPE对CPE改性PVC-U加工性能的影响。结果表明:HDPE... 通过不同结构特征的高密度聚乙烯(HDPE)氯化反应后制得氯化聚乙烯(CPE),研究了CPE改性硬质聚氯乙烯(PVC-U)制品的力学性能;同时也探究了不同相对分子质量特征和部分接枝易于塑化链段的HDPE对CPE改性PVC-U加工性能的影响。结果表明:HDPE的粒径越小和分布越窄、相对分子质量越高及其分布越窄,CPE对PVC-U制品的增韧效果越好;接枝后PVC制品的塑化时间缩减为未接枝时的70%左右,同时CPE改性PVC-U的加工性能变好。 展开更多
关键词 聚氯乙烯 氯化聚乙烯 增韧 性能
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TC4钛合金粉末在SLM工艺中的循环老化行为
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作者 王维 柳宝元 +1 位作者 李长富 李晓丹 《稀有金属材料与工程》 SCIE EI CAS CSCD 北大核心 2019年第1期279-285,共7页
研究了TC4钛合金粉末颗粒形貌、粒度分布、流动性以及选区激光熔化(SLM)成形试样的孔隙率、显微硬度等在循环利用过程中的变化规律,并对一系列性能改变的机理进行分析。结果表明:随循环次数增加,粉末颗粒形貌整体仍保持球形,表面光滑度... 研究了TC4钛合金粉末颗粒形貌、粒度分布、流动性以及选区激光熔化(SLM)成形试样的孔隙率、显微硬度等在循环利用过程中的变化规律,并对一系列性能改变的机理进行分析。结果表明:随循环次数增加,粉末颗粒形貌整体仍保持球形,表面光滑度提高;循环14次后观察不到卫星颗粒;粒度分布经历了集中-分散-集中的变化;多次循环利用后粉末的流动性显著提高;通过对粉末宏、微观形貌的分析可知,上述性能变化趋势均与粉末中细小粉粒和卫星颗粒逐渐减少有关。成形试样孔隙率随循环利用次数增加先增大后减小;显微硬度不受TC4粉末循环利用次数影响。 展开更多
关键词 选区激光熔化 TC4粉末 循环利用 性能
电火花沉积碳化铬基金属陶瓷涂层的微观组织与性能
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作者 张怡 陈志国 +3 位作者 魏祥 汪力 侯志伟 杨威 《稀有金属材料与工程》 SCIE EI CAS CSCD 北大核心 2019年第2期601-607,共7页
采用电火花沉积分别制备了碳化铬基金属陶瓷单涂层和碳化铬基金属陶瓷/Ni复合涂层。采用X射线衍射仪(XRD)、扫描电镜(SEM)、显微硬度计和摩擦磨损试验机对比研究了单涂层和复合涂层的物相、微观组织结构、显微硬度和摩擦磨损性能。结果... 采用电火花沉积分别制备了碳化铬基金属陶瓷单涂层和碳化铬基金属陶瓷/Ni复合涂层。采用X射线衍射仪(XRD)、扫描电镜(SEM)、显微硬度计和摩擦磨损试验机对比研究了单涂层和复合涂层的物相、微观组织结构、显微硬度和摩擦磨损性能。结果表明,两种涂层组织结构致密,与基体呈良好的冶金结合,并在涂层内形成了纳米晶的微观组织。复合涂层中FeCr0.29Ni0.16C0.06韧性相含量增加,在涂层界面处存在过渡层Ni,并以塑性变形的方式释放了更多沉积时产生的热应力,因而涂层裂纹明显减少。复合涂层的峰值硬度(11.86 GPa)虽略低于单涂层,但该涂层具有最小的摩擦系数(0.2462),1 h磨损量仅为单涂层的1/3,因此表现出更好的耐磨性能,其主要磨损机制为磨粒磨损和疲劳磨损。 展开更多
关键词 碳化铬基金属陶瓷涂层 电火花沉积 组织结构 性能
Off-axis electron holography of manganite-based heterojunctions:Interface potential and charge distribution
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作者 令志斌 刘桂菊 +2 位作者 杨成鹏 梁文双 王乙潜 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第4期269-274,共6页
The interfacial electrical potentials and charge distributions of two manganite-based heterojunctions, i.e.,La0.67Ca0.33MnO3/SrTiO3:0.05 wt% Nb(LCMO/STON) and La0.67Ca0.33MnO3/LaMnO3/SrTiO3:0.05 wt% Nb(simplified as L... The interfacial electrical potentials and charge distributions of two manganite-based heterojunctions, i.e.,La0.67Ca0.33MnO3/SrTiO3:0.05 wt% Nb(LCMO/STON) and La0.67Ca0.33MnO3/LaMnO3/SrTiO3:0.05 wt% Nb(simplified as LCMO/LMO/STON), are studied by means of off-axis electron holography in a transmission electron microscope.The influences of buffer layer on the microstructure and magnetic properties of the LCMO films are explored. The results show that when a buffer layer of LaMnO3 is introduced, the tensile strain between the STON substrate and LCMO film reduces, misfit dislocation density decreases near the interfaces of the heterojunctions, and a positive magnetoresistance is observed. For the LCMO/STON junction, positive and negative charges accumulate near the interface between the substrate and the film. For the LCMO/LMO/STON junction, a complex charge distribution takes place across the interface, where notable negative charges accumulate. The difference between the charge distributions near the interface may shed light on the observed generation of positive magnetoresistance in the junction with a buffer layer. 展开更多
关键词 LA0.67CA0.33MNO3 films electron HOLOGRAPHY magnetic properties INTERFACIAL electrical POTENTIAL charge distribution
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