0.2 K～300 K温区氦-3的p-h和T-s图

基于最新的德拜模型氦-3状态方程、氦-3饱和曲线特征方程和熔化曲线特征方程编写了氦-3热物性计算程序.在大量热物性的计算数据的基础上绘制了氦-3在0.2 K～300 K,0.000 1MPa～30 MPa范围内的p-h图和T-s图.与先前基于实验数据绘制的0.2 K～20 K温区氦-3的p-h图和T-s图相比,该图的绘制是建立在热力学理论计算的基础之上,适用温区得到了拓展,随机误差一般在2%以内.     

Thermal conductivity of a CuCrZr alloy from 5 K to room temperatures

Thermal conductivity of a CuCrZr alloy containing of 0.71% of Cr and 0.23% of Zr was measured in the temperature interval from 5 K to 300 K. A method utilizing the measurement of thermal conductivity integral of a sample was verified and applied. Measurements of thermal conductivity, electrical resistivity at 4.2 K and 295 K and of Brinell hardness were performed on solution annealed, precipitation hardened and “as received” materials. The CuCrZr alloy was found to be applicable where high mechanical properties together with high and stable thermal conductivity are required. The possibility to predict the thermal conductivity of precipitation hardened copper alloys from the electrical properties even if the RRR values are lower than 10 was verified at RRR = 5.     

Thermal impedance of thick-film resistance thermometers below 0.2 K

Contributions to the thermal impedance of thick-film resistors (TFRs) are discussed. Measurements of the heat flow along the resistance layer, through the substrate and through the glass overcoating, are presented for commercial resistors mounted on a copper plate in the 30–170 mK temperature range. Because of the relatively good thermal conductivity of the film material (three orders of magnitude higher than that of alumina), the contribution to the heat flow of the resistance layer is never negligible in spite of the thinness of the latter. Suggestions are given for the best mounting of the TFRs as low-temperature thermometers. Less conventional uses of TFRs as thermometers in bolometers are also considered.     

Thermal conductivity of ME771 glass-epoxy laminate from millikelvin temperatures to 4 K

Permaglas ME771 is a glass-epoxy laminate which is suitable for use at cryogenic temperatures. We have measured the thermal conductivity of a sample of this material between 64 mK and 4.2 K in the direction parallel to the reinforcing fibres, enabling us to make a comparison with the better known material G-10CR. The thermal conductivity follows the form that would be expected for such a material, and is similar to that of G-10CR, which has a similar (room temperature) tensile strength. We comment on some confusion that has arisen over the difference between G-10CR, a material specifically produced for cryogenic use, and G-10, the more common equivalent.     

Surface Magnetism of 3He in Grafoil

We report the magnetic susceptibility of ³He in Grafoil filled with pure liquid³He at 27.6 bar and at temperatures down to 0.1 mK with a cw NMR method. It is composed of two contributions: from the bulk liquid and from the adsorbed layer of ³He on the Grafoil surface. The latter shows a well-known strong ferromagnetic tendency and can be fitted to a Curie–Weiss law in the high temperature region. The obtained Weiss temperature is surprisingly large compared with the previous ones.     

Thermal conductivity of argon in the temperature range 107 to 423 K

The thermal conductivity of argon between 107 and 425 K has been measured in a transient hot-wire instrument. The results in the limit zero density have been employed to assess the accuracy of the instrument using exact kinetic theory expressions and has been found to be better than ±0.5%. The data at elevated densities are employed to examine the applicability of the modified Enskog theory in the gaseous phase and the hard-sphere theory in the liquid phase.Paper presented at the Ninth Symposium on Thermophysical Properties, June 24–27, 1985, Boulder, Colorado, U.S.A.     

Thermal conductivity of superconducting UPt3

The thermal conductivity of the heavy-fermion superconductor UPt₃ has been measured on two single crystals of different quality as a function of temperature and applied magnetic field for different orientations of the heat current relative to both the field and the crystalline axes. The temperature dependence of is far from exponential and nearly the same for both crystals, in which the heat current is, respectively, parallel and perpendicular to the hexagonalc axis, suggesting a gap structure with nodes in the basal plane and normal to it. The field dependence of is strongly anisotropic. In the best sample at low fields, where the scattering of heat carriers by vortices is thought to be important, (H) depends on the relative orientation of field and current. On the other hand, at high fields nearH _c2 (in both samples), (H) depends on the relative orientation of field and crystalline axes, reflecting an anisotropy in the gap structure and in the Fermi velocities.     

Thermal conductivity of krypton and xenon at temperatures up to 5000°K

The experimental data on the thermal conductivity of krypton and xenon at temperatures up to 5000°K are correlated. Computational equations are proposed.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 39, No. 5, pp. 852–858, November, 1980.     

Thermal conductivity of (TeO2)0.7(WO3)0.2(La2O3)0.1 glass

The thermal conductivity of (TeO₂)_0.7(WO₃)_0.2(La₂O₃)_0.1 tellurite glass has been measured by a steady-state technique between 77 and 320 K. In this temperature range, the thermal conductivity varies from 0.38 to 1.29 W/(m K). The results were analyzed using fitting equations tested on quartz glass, which made it possible to extend the temperature range of thermal conductivity determined in this study.     

Thermal conductivity of Kevlar 49 between 7 and 290 K

We measured the thermal conductivity of a Kevlar 49 in the 7–290 K temperature range. With a maximum error of 4%, our data are fitted by the simple formula: Kevlar 49 is a candidate material for the supports of CUORE experiment.     

10-290 K环境下聚酰亚胺纤维导热性能研究

为探究聚酰亚胺纤维的热导率随温度变化的规律及成因,利用瞬态电热技术得到聚酰亚胺纤维在不同温度下的热导率。实验研究表明,当温度处于10～290 K范围内,随着温度的降低,聚酰亚胺纤维的热扩散系数逐渐升高,热导率逐渐降低。从晶格振动(声子)导热为主入手,通过研究温度与晶格振动、声子浓度、声子平均自由程等实验参数之间的关系,在排除宏观方面例如气孔等材料瑕疵造成的影响后,得出结晶率是影响聚酰亚胺纤维在玻璃化转变温度附近热导率随温度变化的主要因素,而晶格振动是影响聚酰亚胺纤维在德拜温度附近热导率随温度变化的主要因素。因此可以通过改变结晶率、改善工艺条件等方法,制备满足不同生活、生产、科研需要的聚酰亚胺纤维。     

Thermal conductivity of ethane from 290 to 600 K at pressures up to 700 bar,including the critical region

The paper presents thermal conductivity measurements of ethane over the temperature range of 290–600 K at pressures to 700 bar including the critical region with maximum uncertainty of 0.7 to 3% obtained with a transient line source instrument. A correlation of the data is presented and used to prepare tables of recommended values that are accurate to within 2.5% in the experimental range except near saturation, and in the critical region, where the anomalous thermal conductivity values are predicted to within 5%.Nomenclature a _k , b _ij , b _k , c _i Parameters of the regression model, k=0 to n, i=0 to m, j=0 to n - P Pressure, (MPa or bar) - Q _l Heat flux per unit length (mW · m^–1) - t Time, s - T Temperature, K - T _cr Critical temperature, K - T _r Reduced temperature = T/T _cr - T _w Temperature rise of wire between times t ₁ and t ₂ K - T ^* Reduced temperature difference (T–T _cr)/T _cr - Thermal conductivity, mW · m^–1 · K^–1 - ₁ Thermal conductivity at 1 bar, mW · m^–1 · K^–1 - _bg Background thermal conductivity, mW · m^–1 · K^–1 - _cr Thermal conductivity anomaly, mW · m^–1 · K^–1 - _e Excess thermal conductivity, mW · m^–1 · K^–1 - Density, g · cm^–3 - _cr Critical density, g · cm^–3 - _r Reduced density, = / _cr - ^* Reduced density difference =(- _cr)/ _cr     

Nuclear magnetic resonance of 3He adsorbed submonolayers on Grafoil and argon-coated Grafoil. I. Low coverages

Continuous-wave (cw) nuclear magnetic resonance measurements have been made at 5.5 MHz of ³He adsorbed on Grafoil and on argon (monolayer)-coated Grafoil at coverages x 0.40 (x = 1 corresponds to one monolayer), in the temperature range 0.35–4.21 K. To determine the fractional coverages, the adsorption area of the Grafoil and the monolayer coverages were determined from observations of argon and ³He adsorption isotherms. The results indicate that the adsorbed ³He is highly mobile and behaves as a two-dimensional nonideal Fermi gas. Relative magnetic susceptibilities determined from the NMR lines indicate that the onset of Fermi degeneracy is delayed by spin-independent ³He-³He interactions, as shown by the fit to the data of the quantum second virial coefficient expansion for the magnetic susceptibility. It is established that the residual (coverage-independent) linewidth is largely determined by spin-diffusion through local field gradients in voids in the Grafoil.Supported by a grant from the National Science Foundation.     

Thermal conductivity of air in the range 312 to 373 K and 0.1 to 24 MPa

We have used the transient hot-wire technique to make absolute measurements of the thermal conductivity of dry, CO₂-free air in the temperature range from 312 to 373 K and at pressures of up to 24 MPa. The precision of the data is typically ±0.1%, and the overall absolute uncertainty is thought to be less than 0.5%. The data may be expressed, within their uncertainty, by polynomials of second degree in the density. The values at zero-density agree with other reported data to within their combined uncertainties. The excess thermal conductivity as a function of density is found to be independent of the temperature in the experimental range. The excess values at the higher densities are lower than those reported in earlier work.Nomenclature Thermal conductivity, mW · m^–1 · K^–1 - Density, kg · m^–3 - C _p Specific heat capacity at constant pressure, J · kg^–1 · K^–1 - T Absolute temperature, K - q Heat input per unit wire length, W · m^–1 - t Time, s - K(=/C _p) Thermal diffusivity, m² · s^–1 - a Wire radius, m - Euler's constant (=0.5772 ) - p _c Critical pressure, MPa - T _c Critical temperature, K - _c Critical density, kg · m^–3 - R Gas constant (=8.314 J · mol^–1 · K^–1) - V _c Critical volume, m³ · mol^–1 - Z _c(=p _c V _c/RT _c) Critical compressibility factor     

Thermal conductivity of various glass-reinforced plastics at temperatures below 80 K

The results of thermal conductivity measurements of glass-fabric base laminates CKTφ-5KT, CT0φ-1, CT0φ-HT and uniaxial glass-fibre base laminates 27–63C and AΓ-4C within the 4–80 K temperature range are presented. The thermal conductivities of CKTφ-5KT constituents have also been measured and the thermal conductivity in specific directions has been calculated. The technique used for calculation made it possible to find the thermal conductivities of the matrices of the glass-reinforced plastics under investigation. The effect of cooling heating cycles under vacuum on the thermal conductivity has also been studied.