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On the mechanism of intensified plasma-assisted processing

SURFACE & COATINGS TECHNOLOGY 1997年第3期89卷 197-203页

作者： Adjaottor, AA Ma, E Meletis, EI Materials Science and Engineering Program Department of Mechanical Engineering Louisiana State University Baton Rouge LA 70803-6413 USA

Intensified plasma-assisted processing (IPAP), is a surface modification technique developed recently in our laboratory. Plasma intensification is accomplished by triode discharge and can be utilized for low-pressure, low-temperature diffusion treatments and synthesis of a range of advanced compounds. The energetic flux of ions and neutrals generated in IPAP can create highly favorable surface conditions producing significant improvements in properties ranging from thermal and chemical stability to wear resistance. The objective of the present study was to investigate further the role of energetic particle bombardment on the modification process. IPAP nitriding experiments were carried out on Ti-6Al-4V substrates at specific nitrogen flux levels and Bur energies. Parallel experiments were performed by low-energy, broad-beam nitrogen implantation at comparable ion energies and dose levels. Nitrogen concentrations and penetration depths were determined by depth profiling using AES and microhardness measurements. The experimental results were used to derive effective nitrogen diffusivities to assess the effect of the energetic particle bombardment on the diffusion process. For both IPAP and ion implantation, nitrogen diffusion into titanium nitride and solid solution layers is greatly accelerated compared to conventional ion nitriding. IPAP is almost as effective as low-energy ion implantation in enhancing nitrogen penetration when the two processes use ions of similar energies and dose levels. The energetic neutrals present in IPAP appear to further enhance the growth of surface nitride layers. Analysis also indicates that an optimal ion energy may exist. (C) 1997 Elsevier science S.A.

关键词： intensified plasma-assisted processing

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TIME AND POLING HISTORY DEPENDENT ENERGY STORAGE AND DISCHARGE BEHAVIORS IN POLY(VINYLIDENE FLUORIDE-CO-HEXAFLUOROPROPYLENE) RANDOM COPOLYMERS

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Chinese Journal of Polymer science 2011年第1期29卷 65-80页

作者： Fang-xiao Guan Jing Wang Ji-lin Pan Qing Wang Lei Zhu Polymer Program Institute of Materials Science and Department of Chemical Materials and Biomolecular Engineering University of Connecticut Storrs Connecticut 06269-3136 USA b Department of Materials Science and Engineering Pennsylvania State University University Park Pennsylvania 16802 USA Department of Maeromolecular Science and Engineering Case Western Reserve University Cleveland Ohio 44106-7202 USA

We studied cycle time （0.01-10 s with triangular input waves） and poling history （continuous versus fresh poling） dependent electric energy storage and discharge behaviors in poly（vinylidene fluoride-co-hexafluoropropylene） [P（VDF- HFP）] films using the electric displacement -- the electric field （D-E） hysteresis loop measurements. Since the permanent dipoles in PVDF are orientational in nature, it is generally considered that both charging and discharging processes should be time and poling history dependent. Intriguingly, our experimental results showed that the charging process depended heavily on the cycle time and the prior poling history, and thus the D-E hysteresis loops had different shapes accordingly. However, the discharged energy density did not change no matter how the D-E loop shape varied due to different measurements. This experimental result could be explained in terms of reversible and irreversible polarizations. The reversible polarization could be charged and discharged fairly quickly （〈 5 ms for each process）, while the irreversible polarization depended heavily on the poling time and the prior poling history. This study suggests that it is only meaningful to compare the discharged energy density for PVDF and its copolymer films when different cycle times and poling histories are used.

关键词： P（VDF-HFP） random copolymer Charging and discharging behaviors Time and poling history dependence Dipole switching Compensation polarization.

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LABORATORY STUDY OF BOREHOLE BREAKOUTS IN CORDOVA CREAM - A CASE OF SHEAR FAILURE-MECHANISM

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INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING scienceS & GEOMECHANICS ABSTRACTS 1993年第7期30卷 1047-1056页

作者： HAIMSON, BC SONG, I [&dagger ]Geological Engineering Program Department of Materials Science and Engineering University of Wisconsin-Madison Madison WI 53706 U.S.A.

We subjected vertical boreholes drilled in cubical specimens of Cordova Cream to a 3-dimensional stress field, and increased one or both of the horizontal principal stresses until breakout failure occurred. Acoustic emission, borehole strain, and visual monitoring of the borehole wall during testing revealed four stages of breakout development: crack initiation, extension, breakout formation, and stabilization. Thin section analysis suggests that breakout formation in Cordova Cream is the result of shear failure mechanism. The relationships at breakout stabilization between the two horizontal principal stresses and between the span at the borehole wall and the least horizontal stress suggest a potentially simple method of estimating the far-field state of stress if 'breakouted' borehole geometry is accurately mapped.

关键词： Boreholes

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CHARACTERIZATION OF THE AREA UNDER LOSS MODULUS AND TAN-DELTA-TEMPERATURE CURVES - ACRYLIC POLYMERS AND THEIR SEQUENTIAL INTERPENETRATING POLYMER NETWORKS

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JOURNAL OF APPLIED POLYMER science 1987年第1期34卷 409-422页

作者： CHANG, MCO THOMAS, DA SPERLING, LH Polymer Science and Engineering Program Department of Chemical Engineering Materials Research Center #32 Lehigh University Bethlehem Pennsylvania 18015

Areas under the linear tan δ–temperature (tA) and linear loss modulus–temperature (LA) curves of the polyacrylate and polymethacrylate homologous series and their interpenetrating polymer networks (IPNs) were investigated. For poly(methyl acrylate), LA values are independent of crosslinking level through 25%, but tA decreases. With increasing side group length, on the other hand, tA remains nearly independent of side group length for both homologous series, having values near 50 and 65 (units of K) for the acrylate and methacrylate series, respectively. However, LA decreases steeply with increasing side group length. A phenomenological treatment of areas is presented in order to explain tA and LA behavior semiquantitatively. Both tA and LA exhibit areas characteristic of the structure of the particular polymers. The homopolymer LA areas are additive in determining the area under the corresponding curve for the IPN. This suggested a group contribution analysis for LA, where each moiety contributes specific values to the area.

关键词： INTERPENETRATING POLYMER NETWORKS

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Single-Molecule Vibrational Characterization of Binding Geometry Effects on Isocyanide-Metal Interactions

arXiv

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arXiv 2025年

作者： Bi, Liya Wang, Zhe Balto, Krista Tao, Andrea R. Pascal, Tod A. Zhang, Yanning Figueroa, Joshua S. Li, Shaowei Department of Chemistry and Biochemistry University of California La Jolla San DiegoCA92093-0309 United States Program in Materials Science and Engineering University of California La Jolla San DiegoCA92093-0418 United States Department of Physics and Astronomy University of California IrvineCA92697-4575 United States Institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of China Chengdu611731 China Aiiso Yufeng Li Family Department of Chemical and Nano Engineering University of California La Jolla San DiegoCA92093-0448 United States

Isocyanide-metal binding is governed by σ-donation and π-back-bonding, which affects the energy of the isocyanide stretching mode—a characteristic probe for ligand-metal interactions. While extensive correlations exist between structure and spectroscopy in molecular isocyanide-metal systems, isocyanide interactions with metallic crystalline surfaces, where ligands often bind in various geometries, remain poorly understood. Conventional vibrational spectroscopies, such as infrared and Raman, lack the molecular-scale resolution needed to distinguish these inhomogeneous configurations. In contrast, inelastic electron tunneling spectroscopy with scanning tunneling microscopy (STM-IETS) enables direct visualization of ligand adsorption geometries and their vibrational signatures. Using STM-IETS, here we investigate an metal-adsorbed m-terphenyl isocyanide ligand and find that adsorption geometry on Cu(100) induces a significant shift in isocyanide stretching frequency, even greater than replacing Cu(100) with Ag(111). Density functional theory confirms this shift arises from atomic-scale variations in isocyanide-metal binding. This study elucidates how atomic-scale binding influences the vibrational signatures of isocyanide ligands—an often-overlooked factor in understanding isocyanide-metal interactions. © 2025, CC BY.

关键词： Vibrational spectroscopy

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Scalable Membraneless Direct Liquid Fuel Cells Based on a Catalyst-Selective Strategy

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Energy & Environmental materials 2018年第1期1卷 13-19页

作者： Xingwen Yu Arumugam Manthiram Materials Science&Engineering Program and Texas Materials Institute The University of Texas at AustinAustinTX 78712USA

This perspective presents a membraneless direct liquid fuel cell(DLFC)concept based on a catalyst-selective *** membraneless DLFCs are operated at low temperatures by employing a non-precious cathode catalyst with a high catalytic *** uniqueness is that the inexpensive cathode catalyst only catalyzes the oxygen reduction reaction but does not catalyze the oxidation reaction of a specific ***,during the operation of DLFCs,the liquid fuel can enter the cathode freely without any concern of fuel *** catalyst-selective approach tactfully avoids the use of high-cost or technically unviable ion-exchange polymer membranes in *** catalyst-selective operating principle also overcomes the scalability issue of the traditional laminar-flow membraneless *** a proper management of the anode and cathode catalysts in the cell,a variety of inexpensive,renewable alcohols,and small-molecule organics can be employed as anode *** innovative approach of membraneless alkaline DLFCs offers a great opportunity for the development of inexpensive energy-generation systems for both mobile and stationary *** addition to summarizing the principle and the research progress of the unique membraneless DLFC platform,the challenges and future research directions are presented.

关键词： catalyst uniqueness overcome

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Highly active vitamin B₁ Pickering emulsion interface catalysis systems for Knoevenagel condensation

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Surfaces and Interfaces 2025年 68卷

作者： Zhang, Po Liu, Daliang Chang, Xiaohong Song, Xi-Ming Song, Zhining Li, Quan Liaoning Key Laboratory for Green Synthesis and Preparative Chemistry of Advanced Materials College of Chemistry Liaoning University Shenyang 110036 China Center for Analysis and Testing College of Chemistry Liaoning University Shenyang 110036 China Institute of Advanced Materials and School of Chemistry and Chemical Engineering Southeast University Nanjing Nanjing 211189 China Materials Science Graduate Program Kent State University Kent 44242 OH United States

Vitamin B1 (VB1) is characterized by its non-toxicity, low cost, and good stability, making it a highly promising biobased green catalyst with significant potential for development. Due to its favorable water solubili... 详细信息

Vitamin B₁ (VB₁) is characterized by its non-toxicity, low cost, and good stability, making it a highly promising biobased green catalyst with significant potential for development. Due to its favorable water solubility, research on VB₁ as a catalyst is currently limited to homogeneous and single-solvent heterogeneous catalytic systems, and there are inherent limitations in how to fully dissolve substrates to enhance catalytic performance and expand the range of reaction substrates. In this study, VB₁ was immobilized onto the surface of graphene oxide nanosheets (GOs) through multiple interaction forces, thereby forming GOs-VB₁ composite nanosheets. With the nanosheets, stable toluene/water Pickering emulsion interfacial catalysis (PEIC) systems were constructed for Knoevenagel condensation. By using the PEIC systems, the yields of eight benzylidenemalononitrile derivatives reached 85%-95% after 30 min reaction under static reaction condition of non-agitation at 40 °C with the dosage of only 0.35 wt% GOs-VB₁, much higher than that catalyzed by VB₁ or GOs-VB₁ in the corresponding single or mixed solvents under the same conditions. The excellent catalytic performance of the VB₁-based PEIC systems under mild reaction conditions is attributed to the sufficient dissolution of the reactants (malononitrile and benzaldehyde or its derivatives) in the continuous and dispersed phases of the emulsion, respectively, as well as the stable enrichment of the catalyst VB₁ at the large emulsion interface. The PEIC systems exhibited consistently high reaction yields even after undergoing six of recycling. © 2025

关键词： Graphene oxide Knoevenagel condensation Pickering emulsion interfacial catalysis (PEIC) Vitamin B1 (VB1)

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EXTENDED VACANCY-VACANCY LIQUID MODEL

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METALLURGICAL AND materials TRANSACTIONS A-PHYSICAL METALLURGY AND materials science 1995年第10期26卷 2597-2610页

作者： BREBRICK, RF YU, TC Materials Science and Engineering Program Department of Mechanical Engineering Marquette University Milwaukee Trace Storage Technology Taiwan Republic of China

A quasicrystalline model of a binary liquid in which two sublattices containing randomly distributed vacancies is developed via statistical thermodynamics. The relative partial molar quantities are obtained. The constraints imposed upon the adjustable model parameters to ensure that the Schottky constant increases with increasing temperature but never exceeds unity are developed, as well as the constraints entering upon application to a AC system forming a congruently melting, narrow homogeneity-range compound AC (s). The model is an extension of an earlier version for liquids and of analogous models for narrow homogeneity-range compounds, AC (s), in that the excess Gibbs energies of vacancy creation are cubic functions of the atomic fraction. The model is also an alternative to associated solution models which would assume a single equiatomic associated species. The model is then applied to systems of varying polarity but all forming a narrow homogeneity-range crystalline compound whose stoichiometric composition is 50 at. pct. Quantitatively good fits are obtained for the Hg-Te, Cd-Te, Zn-Te, and Pb-Te systems and, for the first three systems, are comparable to fits obtained with the associated solution model using the same experimental data. Quantitatively good fits are also obtained for the less polar In-Sb and Ga-Sb systems, and these are comparable to those obtained by us with a Margules-type model in which the enthalpy of mixing for the liquid is a quartic function of atom fraction and a quadratic function of temperature. Finally, the predictions for the enthalpy of mixing at temperatures above the present range of experimental data are given and discussed for the various systems and models. It appears the model given here is appropriate for the type of systems tested.

关键词： Binary alloys

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Nanocrystalline Ag formed by low-temperature high-energy mechanical attrition

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NANOSTRUCTURED materials 1997年第1期8卷 91-100页

作者： Xu, J Yin, JS Ma, E Materials Science and Engineering Program Department of Mechanical Engineering Louisiana State University Baton Rouge LA 70803-6413 USA

High-energy mechanical attrition of Ag powders was conducted at the liquid nitrogen temperature without using process control agents. This process improves the milling efficiency and yields powders with truly nanocrystalline grain structure. The microhardness and grain growth behavior at different storage temperatures, as well as the excess enthalpy introduced by milling, have been studied and compared with the results for nanophase Ag prepared using other methods.

关键词： Nanostructured materials

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EFFECT OF OXYGEN-CHEMISORPTION ON CHAR GASIFICATION REACTIVITY PROFILES OBTAINED BY THERMOGRAVIMETRIC ANALYSIS

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FUEL 1988年第12期67卷 1691-1695页

作者： LIZZIO, AA PIOTROWSKI, A RADOVIC, LR Fuel Science Program Department of Materials Science and Engineering The Pennsylvania State University University Park PA 16802 USA

The gasification reactivity of an Illinois No. 6 bituminous coal char was determined in oxygen and carbon dioxide using thermogravimetric analysis (TGA). Extensive tests were carried out to ensure the absence of diffusional limitations. Measurements of chemically controlled rates were verified by analysing the activation energies for reactions of the char at various conversion levels. The effect of stable carbon-oxygen complex formation on TGA reactivity profiles was investigated. For disordered carbons (e.g. coal chars) gasified in oxygen, the results showed that the observed differences between reactivity profiles obtained by TGA and those obtained by product gas analysis (e.g. non-dispersive infrared spectroscopy, i.r.) can be attributed to significant amounts of stable complex being formed during the initial stages of reaction. The fact that TGA reactivity profiles become equivalent to i.r. reactivity profiles, when corrected to account for stable complex formation, suggests that the former may not be accurate representations of the variations in intrinsic reaction rates and should be used with caution when attempting to validate proposed models of char gasification kinetics. The extent to which stable complex forms during char gasification was used to explain the observed differences in the reactivity profiles obtained for reactions of char in oxygen and carbon dioxide.

关键词： thermogravimetric analysis oxygen char

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