Thermal conductivity measurement Copper 252, Table

Electrical—Thermal Conductivities. Electrical conductivities of alloys (Table 5) are often expressed as a percentage relative to an International Annealed Copper Standard (lACS), ie, units of % lACS, where the value of 100 % lACS is assigned to pure copper having a measured resistivity value of 0.017241 Q mm /m. The measurement of resistivity and its conversion to % lACS is covered under ASTM B193 (8). 

Electrical conductivity is comparatively easy to measure, whereas thermal conductivity is not. Electrical conductivity values for the important cast alloys are Hsted in Table 2. Eigure 1 schematically shows the electrical conductivity of cast copper-base alloys compared with various other cast metals and alloys. The equation Y = 4.184 + 3.93a gives an approximation of thermal conductivity in relation to electrical conductivity, where Tis in W/(m-K) at 20°C and X is the % lACS at 20°C. 

We have carried out the measurement of the thermal conductivity of six copper samples, whose characteristics are shown in Table 11.2. 

Thermal Conductivity. Conductivity measurements were made of tape candidates to determine whether or not they would satisfy the cable design requirements listed in Table I. The measurements were made for BNL by Jelinek of BCL using the apparatus illustrated in Fig. 7. The method was a modified steady-state conductivity technique where a temperature gradient was established between two copper plates separated by four layers of polymeric film. (Multilayer measurements were always made to approximate the series interfacial resistivity that would be present in lapped cable configurations.) One plate was attached to a controlled heat sink and a measured quantity of heat was added to the other plate by means of an electric heater. With the use of a liquid helium throttling dewar, the ambient temperature could be controlled to within 1 K. (Complete details of the conductivity measurement method are included in Appendix II of this paper.)... 

In systems in which two materials are dispersed homogeneously, the logarithmic mixing rule lnKco=VcelnKce+VmlnK , is applied. Table 9-2 shows the results of measurement of the thermal conductivity of LTCC copper... 

Column 2 of Table II shows a comparison of the measured apparent mean thermal conductivity for Cab-O-Sil H-5 with silver, nickel, copper, and aluminum powders added by weight. Assuming there are the same number of metal particles per gram of Cab-O-Sil, and that the particle size and emissivities of the metal powders are very nearly the same, then there should be no significant difference in the opacifing effect of the four metal powders tested. Because the metal powders were added as percent by weight rather than as the number of particles per gram of Cab-O-Sil, the measured of the samples can not be ex-... 

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