共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
3.
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. 相似文献
4.
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. 相似文献
5.
6.
7.
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. 相似文献
8.
Akira Yamaguchi Takamichi Watanuki Ryuichi Masutomi Hidehiko Ishimoto 《Journal of Low Temperature Physics》2004,134(1-2):67-72
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. 相似文献
9.
U. V. Mardolcar C. A. Nieto de Castro W. A. Wakeham 《International Journal of Thermophysics》1986,7(2):259-272
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. 相似文献
10.
K. Behnia L. Taillefer J. Flouquet D. Jaccard K. Maki Z. Fisk 《Journal of Low Temperature Physics》1991,84(3-4):261-278
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. 相似文献
11.
12.
N. B. Vargaftik Yu. D. Vasilevskaya 《Journal of Engineering Physics and Thermophysics》1980,39(5):1217-1222
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. 相似文献
13.
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. 相似文献
14.
15.
Thermal conductivity of Kevlar 49 between 7 and 290 K 总被引:1,自引:0,他引:1
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. 相似文献
16.
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。 相似文献
17.
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 相似文献
18.
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. 相似文献
19.
A. C. Scott A. I. Johns J. T. R. Watson A. A. Clifford 《International Journal of Thermophysics》1981,2(2):103-114
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 相似文献
20.
《低温学》1987,27(8):429-432
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. 相似文献