Determination of Vapor Pressure of Liquid Copper by Carrier Gas Method

The relationship between the vapor pressure of liquid copper and the flow rate of carrier gas argon was discussed, when the carrier gas method was used to determine the vapor pressure of liquid copper at 1892 K. The proper argon flow rate range obtained was 150-500 mL/min and enough evidence was provided to verify the vapor pressure-flow rate of carrier gas relationship at the target temperature. Based on the proper flow rate range, the vapor pressure of liquid copper was measured at 1609-1892 K. The relationship of vapor pressure-temperature obtained by the method of regression analysis can be expressed as： In（p/Pa） = （25.470 -I- 0.903） - （39099.8 -4- 1574.5）/T, Further, the thermodynamic properties including the heat of vaporization and the Gibbs free energy of the Cu （I） = Cu （g） reaction were calculated by the vapor pressiJre obtained over the temperature range covered.     

U－23at％Zr合金的焓、比热容和相变潜热

用下落式铜卡计法测量了室温到１０７３Ｋ之间Ｕ－２３ａｔ％Ｚｒ（即Ｕ－１０ｗｔ％Ｚｒ）合金的焓，计算了８８０Ｋ以下相应的平均比热容和微分比热容。在焓－温度曲线上观察到在８８９、９３４、９６１Ｋ左右焓值的跳跃，这是和Ｕ－Ｚｒ系相图上固相线下前三个相变温度相对应的。算得相应的相变潜热分别是５７９、１１８和２８１２Ｊ／ｍｏｌ。     

Measurements of Heat Capacity and Enthalpy of Phase Change Materials by Adiabatic Scanning Calorimetry

Phase change materials (PCMs) are substances exhibiting phase transitions with large latent heats that can be used as thermal storage materials with a large energy storage capacity in a relatively narrow temperature range. In many practical applications the solid–liquid phase change is used. For applications accurate knowledge of different thermal parameters has to be available. In particular, the temperature dependence of the enthalpy around the phase transition has to be known with good accuracy. Usually, the phase transitions of PCMs are investigated with differential scanning calorimetry (DSC) at fast dynamic scanning rates resulting in the effective heat capacity from which the (total) heat of transition can be determined. Here we present adiabatic scanning calorimetry (ASC) as an alternative approach to arrive simultaneously at the equilibrium enthalpy curve and at the heat capacity. The applicability of ASC is illustrated with measurements on paraffin-based PCMs and on a salt hydrate PCM.     

一种温度间接测定法

本针对一些工程需要,提出了一种温度间接测定法,并阐述了该方法的原理和模型。通过实验,验证了该法的可行性和可靠性,从而在一定程度上拓宽了非接触式测温法的范围。     

气相转移法制备多孔双相沸石复合物

采用气相转移法制备了同时含有Y和ZSM-5沸石的双相沸石复合物。采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、N₂吸附-脱附和骨架红外(FT-IR)等手段对合成的样品进行了表征。结果表明, 合成的样品受Y型沸石的添加量、干胶制备条件和气相转移法转化条件的影响; 水热预处理后的ZSM-5沸石前驱体中具有ZSM-5沸石的骨架特征振动峰, 归结于ZSM-5沸石晶核或微晶的形成, 这有利于在气相转移法转化过程中引导或促使体系向ZSM-5沸石相的转变, 并有利于抑制ZSM-35杂晶的形成; Y型沸石在蒸汽处理过程中的脱铝过程导致合成的沸石复合物具有介孔结构。     

气相法制备纳米铁颗粒新进展

纳米铁颗粒在磁性、催化和吸波等方面都展现了优异的特性,具有广阔的应用前景.在过去的几十年里,国内外许多学者开展了对纳米铁颗粒制备、结构和性能的研究.着重阐述了纳米铁颗粒的气相法制备方法,并指出了这一领域今后的研究方向.     

气相法制备纳米铁颗粒新进展

纳米铁颗粒在磁性、催化和吸波等方面都展现了优异的特性，具有广阔的应用前景。在过去的几十年里，国内外许多学者开展了对纳米铁颗粒制备、结构和性能的研究。着重阐述了纳米铁颗粒的气相法制备方法，并指出了这一领域今后的研究方向。     

Vapor Pressure, Speed of Sound, and PVT-Properties of R-404a in the Vapor Phase

The density (300–363 K, up to 3.5 MPa) and speed of sound (293–373 K, 7.5–480 kPa) in gaseous R-404a have been studied by an isochoric piezometer method and an ultrasonic interferometer, respectively. The pressures of the saturated vapor along the dew line were measured from 298 to 330 K. The experimental uncertainties of the temperature, pressure, density, and speed-of-sound measurements were estimated to be within ±20 mK, ±1.5 kPa, ±0.15%, and ±(0.1–0.2)%, respectively. On the basis of the obtained data, the isobaric molar heat capacity of R-404a was calculated for the ideal-gas state. An eight-coefficient Benedict–Webb–Rubin equation of state has been developed for the gaseous phase of R-404a.     

An Accurate Vapor Pressure Equation with Good Extrapolation Characteristics

A new vapor pressure equation that has only three adjustable parameters and a simple form is presented in this paper. The equation is valid over the entire range from the triple point to the critical temperature for a chemically diverse set of compounds. It can represent the experimental data with an accuracy comparable to the Wagner vapor pressure equation. The advantage of the new equation is that it can be used to extrapolate well from a small amount of data in the usual range to the entire vapor–liquid coexistence region both up to the critical temperature and down to the triple point. Satisfactory results are presented for more than 40 substances in tables, and it has been shown that the new vapor pressure equation is generally valid in a wide range.     

硅藻土吸附正十八烷高相变焓复合相变材料的制备及其性能研究

利用硅藻土比表面积大、孔洞多因而吸附性好的特点,吸附正十八烷,制备出形态稳定、高相变焓的硅藻土/正十八烷复合相变材料.利用扫描电镜(SEM)观察其表面形貌,采用红外光谱法(FTIR)分析材料的微观结构,用热重分析仪(TG)及受热形态变化对其热稳定性进行了表征,用示差扫描量热法(DSC)对其相变温度及相变焓进行了测定.结果表明:制得的复合相变材料的分解温度在240℃以上,当正十八烷的吸附量不超过40％时,在高于相变温度时未泄漏,相变温度在26～31℃之间,并且具有很高的相变焓(131.6～163.3 J/g),是一类形态稳定、相变焓高、热性能良好、应用前景广泛的节能环保材料.     

雷德法饱和蒸汽压校准方法的探讨

石油产品是各种烃类的复杂混合物,在一定温度下,油品的馏分越重,饱和蒸汽压越小,直接关系着产品的质量,所以对于饱和蒸汽压的温度和压力的校准就极其重要.本文对饱和蒸汽压的温度、压力两个参数的校准方法进行了详细介绍,保证了在工作中数据的准确性,提高了产品质量.     

Enthalpy of Phase Change Materials as a Function of Temperature: Required Accuracy and Suitable Measurement Methods

Phase change materials (PCMs) are thermal storage materials with a high storage density for small temperature range applications. In the design of latent heat storage systems, the enthalpy change of the PCM has to be known as a function of temperature with high precision. During dynamic measurements, the sample is not in thermal equilibrium, and therefore the measured value is not the equilibrium value. The influence of non-equilibrium on the measurement results can be quantified by doing measurements during heating and cooling with any measurement instrument. Measurements carried out by differential scanning calorimetry (DSC) and by the T-history method are presented and discussed. To characterize encapsulated PCM objects, measurements on the whole objects should be carried out. A measurement setup for this purpose is also presented. The obtained precision meets typical application requirements, and good agreement between results obtained with the different methods is demonstrated.     

Enthalpy Calibration Method for Differential Scanning Calorimeters

Measurement Techniques - A method for enthalpy calibration of differential scanning calorimeters is described which makes it possible to eliminate the existing limits on the temperature range...     

高频热等离子体气相合成一维纳米氧化锌研究

把锌粉原料加入到高频常压热等离子体弧中,使锌粉加热气化,然后与加入等离子体反应器中的氧气反应,合成出了直径为50nm、长度超过2靘的一维棒状纳米氧化锌.研究了氧分压和锌粉加料速度对合成产物形貌的影响,结果表明,通过控制这些参数,可以调控合成的氧化锌纳米棒长径比.采用XRD、SEM、TEM和HRTEM对产物的形貌和结构进行了表征,并衷征了合成的氧化锌纳米棒的光致发光性能.     

基于相变存储器的相变存储材料的研究进展

相变存储器具有非易失性、循环寿命长、元件尺寸小、功耗低、多级存储、与现有集成电路工艺相兼容等诸多优点,被认为是最具潜力的下一代存储器.简要介绍了相变存储材料的工作原理和对相变存储材料的性能要求,综述了近年来国内外在相变材料存储性能的优化、存储机理以及面临的关键问题等方面的最新研究成果,最后展望了相变存储材料的研究和发展趋势.     

一种气相缓蚀剂的密闭空间定量评价方法

在总结了国内外文献中气相缓蚀剂缓蚀性能评价方法的基础上,提出了一种密闭空间定量评价方法,并对试验条件进行了优化,得到的最佳试验条件为:试验温度为60℃;循环周期为加热8h静置16h,24h为一个循环;试验周期为1d;溶液为含NaHCO3,Na2SO4,NaCl的质量浓度分别为1g/L的电解质溶液60mL。对单组分气相缓蚀剂和复配气相缓蚀剂采用密闭空间定量评价方法进行了定量评价和验证,发现总趋势与废止的部颁92年标准结果类似,说明这种评价法能为高效、快速、定量评价气相缓蚀剂的缓蚀性能提供新的思路。     

Metallorganic Vapor Phase Epitaxy of(AlGa)InP on GaAs at Atmospheric Pressure

High quality (AlGa)InP epilayers lattice matched on GaAs substrates were grown by atmosphericpressure metallorganic vapor phase epitaxy (AP-MOVPE).The relationship between surfacemorphologies and lattice mismatches was studied.The influence of Al incorporation to thephotoluminescence and electronic properties of AlGaInP was measured.The applicability of growthat atmospheric pressure and the passivation of Zn in AlGaInP were discussed.     

Godunov Method for Stefan Problems with Enthalpy Formulations

A Stefan problem is a free boundary problem where a phase boundary moves as a function of time. In this article, we consider one-dimensional and two-dimensional enthalpy-formulated Stefan problems. The enthalpy formulation has the advantage that the governing equations stay the same, regardless of the material state (liquid or solid). Numerical solutions are obtained by implementing the Godunov method. Our simulation of the temperature distribution and interface position for the one-dimensional Stefan problem is validated against the exact solution, and the method is then applied to the two-dimensional Stefan problem with reference to cryosurgery, where extremely cold temperatures are applied to destroy cancer cells. The temperature distribution and interface position obtained provide important information to control the cryosurgery procedure.     

Vapour Pressure and Enthalpy of Sublimation of C70

The vapour pressure of pure C₇₀ was measured in the temperature range 650-850 K by using the Knudsen effusion mass spectrometry resulting in the equation log(p/Pa) = -10219±78 / T(K) ± 11.596±0.065. The second law enthalpy of sublimation of C₇₀ was determined to be 195.7±1.1 kJ/mol.