A Thermophysical Property Databank for Technically Important Gases and Liquids

A thermophysical property databank for technically important gases and liquids has been created. It provides users with data for nearly 30 substances: monatomic and diatomic gases, air, water and steam, carbon dioxide, ammonia, some hydrocarbons, and refrigerants. The coefficients of the equations of state and equations for calculating transport properties, the ideal-gas functions, the saturated vapor pressure, and the melting pressure are provided for each substance. The system of programs allows the calculation of the compressibility factor, density, enthalpy, entropy, isochoric and isobaric specific heats, speed of sound, Joule–Thomson coefficient, viscosity, and thermal conductivity and some other properties. These values can be determined in the single-phase and two-phase regions and on the phase-equilibrium lines at temperatures from the triple point up to 500 to 1500 K and at pressures up to 100 MPa (for monatomic and diatomic gases, up to 2500 to 3000 K and 300 MPa). Properties can be calculated for the following nine combinations of independent variables: T, ; T, p; T, s; T, x; p, ; p, h; p, s; p, x; and h, s. The software of the databank has a modular structure and permits an increase in the number of substances, properties, and independent variables.     

氢对TC21钛合金热物理性能的影响

目的 获得氢含量对TC21钛合金密度、热扩散系数、比热容和热导率等热物理性能的影响规律.方法 利用固态置氢法对TC21钛合金进行氢处理,利用固体密度测试仪、激光导热仪和差示扫描量热仪等设备测定原始及含有不同氢含量TC21钛合金的热物理性能.结果 随着氢含量的增加,TC21钛合金的密度呈线性降低趋势;TC21钛合金在不同...     

Synthesis of Free-Standing Pd-Ni-P Metallic Glass Nanoparticles with Durable Medium-Range Ordered Structure for Enhanced Electrocatalytic Properties

Topologically disordered metallic glass nanoparticles (MGNPs) with highly active and tailorable surface chemistries have immense potential for functional uses. The synthesis of free-standing MGNPs is crucial and intensively pursued because their activity strongly depends on their exposed surfaces. Herein, a novel laser-evaporated inert-gas condensation method is designed and successfully developed for synthesizing free-standing MGNPs without substrates or capping agents, which is implemented via pulse laser-induced atomic vapor deposition under an inert helium atmosphere. In this way, the metallic atoms vaporized from the targets collide with helium atoms and then condense into short-range-order (SRO) clusters, which mutually assemble to form the MGNPs. Using this method, free-standing Pd₄₀Ni₄₀P₂₀ MGNPs with a spherical morphology are synthesized, which demonstrates satisfactory electrocatalytic activity and durability in oxygen reduction reactions. Moreover, local structure investigations using synchrotron pair distribution function techniques reveal the transformation of SRO cluster connection motifs of the MGNPs from face-sharing to edge-sharing modes during cyclic voltammetry cycles, which enhances the electrochemical stability by blocking crystallization. This approach provides a general strategy for preparing free-standing MGNPs with high surface activities, which may have widespread functional applications.     

Development and Current Status of the Korea Thermophysical Properties Databank (KDB)

Physical property data, phase equilibrium data, and predictive models are essential parts of process design and operation. With the support of the Ministry of Commerce, Industry and Energy (MOCIE) of Korea, four universities collaborated to develop a thermophysical property databank and to obtain experimental data. In this paper topics related to the development and use of the thermophysical properties and phase equilibrium database are discussed. The databank contains about 4000 pure components and 5000 phase equilibrium data sets. Most of the data were collected along with the experimental uncertainties. Various estimation methods and thermodynamic models were included to calculate properties and phase equilibria. Data can be searched for with a stand-alone program or using an Internet web site. The current status and future prospects of the KDB (Korean Thermophysical Properties Databank) are discussed.     

Nondestructive Method for Determining the Thermophysical Properties and Temperature Transitions of Thermoplastics

A method is described making it possible to increase the efficiency and accuracy of determining thermophysical properties and temperature transitions of thermoplastic billets under production conditions without destroying them.__________Translated from Izmeritel’naya Tekhnika, No. 5, pp. 59–61, May, 2005.     

多元Al合金的热力学和热物理数据库的建立及凝固过程显微组织演变的模拟

介绍了相图热力学及热物理性能数据库的建立方法;综述了国内外学者构筑多元Al合金相图热力学和热物理性能数据库的研究工作。并介绍了使用相场方法,使用热力学和热物理性能数据库模拟多元Al合金凝固时显微组织演变的几个实例。最后展望了新一代热力学和热物理性能数据库建立及凝固过程显微组织演变定量模拟未来的可能发展方向。     

Overload effects on fatigue crack‐tip fields under plane stress conditions: surface and bulk analysis

The surface crack opening displacements are characterised by digital image correlation for a (thin) plane stress 316 stainless steel compact tension sample subjected to an overload event. This supports a traditional plasticity‐induced closure interpretation showing a knee in the closure response prior to overload, an absence of closure in the accelerated growth regime followed by accentuated closure in the retardation regime. By contrast, measurement of the mid‐thickness elastic strain field behind and ahead of the crack made by synchrotron X‐ray diffraction shows no evidence of significant crack face contact stresses behind the crack tip on approaching minimum loading. Rather the changes during loading and overloading can mostly be explained by a simple elastic plastic analysis using a value of the yield stress intermediate between the initial yield stress and the UTS. This shows very significant compressive reverse plastic strains ahead of the crack that start to form early during unloading. At the moment it is not clear whether this difference is because of the increasing stress intensity applied as the crack grows, or for some other reason, such as prevention of the crack faces closing mid‐thickness due to the reverse plastic zone.     

Automated System for Calculating Thermophysical Properties of Fluids and Thermal Processes of Cryogenic Plants

An automated system for calculating thermophysical properties of gases and liquids over a wide range of parameters has been developed. On the basis of values of the properties, the processes of isothermal compression, adiabatic throttling, polytropic expansion, heat exchange in two- and multi-stream heat exchangers, separation of vapor-liquid mixtures in the liquid vessel, and rectification in an air separation plant can be analyzed. For a specified structure scheme of a cryogenic plant, optimization of a corresponding thermodynamic cycle can be fulfilled.     

Specific Heat and Thermal Transport Measurements of Reactive Metallic Alloys by Noncontact Calorimetry in Reduced Gravity

Experimental concepts, application, and recent results of noncontact calorimetry inculding ac-specific heat and thermal transport property measurement of reactive metallic specimens are described. The method is based on induction heating in an electromagnetic levitation device. Experiments have been performed in reduced gravity onboard Spacelab. A heat flow model is discussed regarding conditions for precise specific heat determination from the temperature response to modulated heating power input as well as determination of thermal transport properties from the transient temperature response. Modulation techniques were developed for application in the metastable regime of the undercooled melt, where processing time is a critical issue. Results to be discussed include the total hemispherical emissivity of a bulk metallic glass-forming alloy revealing effects of surface segregation, thermal conductivity measurements, and application of ac calorimetry in the two-phase region.     

Thermophysical Properties and Normal Spectral Emittance of Iridium up to 3500 K

An ohmic pulse-heating experiment together with radiometry and μs-photopolarimetry is deployed at the Institute of Experimental Physics, Graz University of Technology, to obtain temperature-dependent thermophysical properties of conducting samples in the solid and molten states. This experimental setup has been used within the present work to gather data for solid and liquid iridium. Results for both thermophysical properties, as well as the normal spectral emittance obtained at a wavelength of 684.5 nm up to 3500 K are reported. The newly obtained values for iridium are presented in graphical and tabular form and compared to available literature data. The uncertainties for all reported properties are stated and it follows that, considering these expanded uncertainties, the recent data are in very good agreement with literature sources. Mutually motivated by these good results and by the scarce (if any) data available for the liquid state, the thermal conductivity and thermal diffusivity of liquid iridium are estimated by means of the Wiedemann–Franz law.     

Absolute Measurement of Thermophysical and Optical Thin-Film Properties by Photothermal Methods for the Investigation of Laser Damage

Perspectives and limits of the application of the photothermal technique are given for the measurement of absorption, thermal, and thermoelastic properties in thin films. The peculiarities of this technique in the frequency and time domains are discussed in some detail, and selected important results with respect to laser damage studies in optical coatings are pointed out. Emphasis is placed on the absolute measurement of both optical and thermophysical properties in dielectric materials in thin-film form and, also, on the influence of both absorption and changed thermal properties in thin films on their thermally induced laser damage resistance.     

金属箔饰面家具表面理化性能检测及标准化研究

本文提出了金属箔饰面家具的表面理化性能研究的必要性,并从表面胶合强度、表面漆膜理化性能(耐液性、耐湿热、耐干热、附着力、耐冷热温差、耐磨性、抗冲击)等多个方面提出了检测要求和试验方法,通过验证试验证明了良好的测试效果,并在最后展望了应用前景。     

Structure and Thermophysical Properties of Fullerene C60 Aqueous Solutions

The structure and thermophysical properties of fullerene C₆₀aqueous solutions were investigated both experimentally and theoretically. The aggregation kinetics results indicated that the structure of fullerene C₆₀aggregates in water could be described as a fractal system. The IR and electronic absorption spectra obtained confirm the presence of the crystalline phase in aqueous solution. The numerical values of thermodynamic coefficients _P, _T, _S,c _P, andc _V, and sound velocity were determined from the measured (P–V–T) data. The vibrational spectrum of the crystalline structure (T_hsymmetry group) formed from the hydrated single fullerene C₆₀molecules in aqueous solutions was calculated using the molecular dynamics approach.     

Setting Up a Databank on the Properties of Substances and Materials: A Task Undertaken by the State Reference Data Service

Research results are reported for a databank on the thermophysical properties of substances and materials, which covers researches in the Soviet Union and Russia between 1950 and 2000. An archive of 3475 documents has been set up, which provides bibliographic information on the publications containing the original experimental data and which has been implemented in the Lotus Notes environment. The database organization and retrieval in it are considered.     

Synthesis and Structural Evolution of Nickel–Cobalt Nanoparticles Under H2 and CO2

Bimetallic nanoparticle (NP) catalysts are interesting for the development of selective catalysts in reactions such as the reduction of CO₂ by H₂ to form hydrocarbons. Here the synthesis of Ni–Co NPs is studied, and the morphological and structural changes resulting from their activation (via oxidation/reduction cycles), and from their operation under reaction conditions, are presented. Using ambient‐pressure X‐ray photoelectron spectroscopy, X‐ray absorption spectroscopy, and transmission electron microscopy, it is found that the initial core–shell structure evolves to form a surface alloy due to nickel migration from the core. Interestingly, the core consists of a Ni‐rich single crystal and a void with sharp interfaces. Residual phosphorous species, coming from the ligands used for synthesis, are found initially concentrated in the NP core, which later diffuse to the surface.     

Effects of Pb Intercalation on the Structural and Electronic Properties of Epitaxial Graphene on SiC

The effects of Pb intercalation on the structural and electronic properties of epitaxial single‐layer graphene grown on SiC(0001) substrate are investigated using scanning tunneling microscopy (STM), noncontact atomic force microscopy, Kelvin probe force microscopy (KPFM), X‐ray photoelectron spectroscopy, and angle‐resolved photoemission spectroscopy (ARPES) methods. The STM results show the formation of an ordered moiré superstructure pattern induced by Pb atom intercalation underneath the graphene layer. ARPES measurements reveal the presence of two additional linearly dispersing π‐bands, providing evidence for the decoupling of the buffer layer from the underlying SiC substrate. Upon Pb intercalation, the Si 2p core level spectra show a signature for the existence of Pb? Si chemical bonds at the interface region, as manifested in a shift of 1.2 eV of the bulk SiC component toward lower binding energies. The Pb intercalation gives rise to hole‐doping of graphene and results in a shift of the Dirac point energy by about 0.1 eV above the Fermi level, as revealed by the ARPES measurements. The KPFM experiments have shown that decoupling of the graphene layer by Pb intercalation is accompanied by a work function increase. The observed increase in the work function is attributed to the suppression of the electron transfer from the SiC substrate to the graphene layer. The Pb intercalated structure is found to be stable in ambient conditions and at high temperatures up to 1250 °C. These results demonstrate that the construction of a graphene‐capped Pb/SiC system offers a possibility of tuning the graphene electronic properties and exploring intriguing physical properties such as superconductivity and spintronics.     

加热过程中小鼠皮肤热物性及力学参数变化研究

本文以小鼠作为实验对象,研究了离体小鼠皮肤组织加热过程中热物性及力学参数的变化,讨论了温度及水分等因素的影响规律。结果表明:在加热过程(37～47℃)中,皮肤组织应力应变曲线近似为线性,弹性模量与温度相关,且随着温度的升高而逐渐减小,泊松比变化与之相似;加热初期(37～45℃),组织含水率减少不明显,导热系数随温度的升高而缓慢增加;随着温度的升高与时间的推移,组织逐渐失水,含水率对导热系数的影响高于温度对其的影响,45℃时导热系数开始急剧下降,在45～47℃,导热系数值下降了5. 4%,比热容变化与之相似。