Article
Thermal conductivity of HTS assemblies based on soldered and adhesive joints at cryogenic temperatures
I. V. Martirosian
NRNU MEPhI, Kashirskoye Highway, 31, 115409, Moscow, Russia
e-mail: mephizic@gmail.com
A. Yu. Malyavina
NRNU MEPhI, Kashirskoye Highway, 31, 115409, Moscow, Russia
M. A. Balakina
NRNU MEPhI, Kashirskoye Highway, 31, 115409, Moscow, Russia
S. V. Pokrovskii
NRNU MEPhI, Kashirskoye Highway, 31, 115409, Moscow, Russia
Abstract
In this work, the results of a comparative study are presented for the effective thermal conductivity of stacks of hightemperature superconducting tapes based on YBa2Cu3O7-x, assembled using three joining technologies: soldering with solder POS-61 and bonding with two-component compounds TO-29-2 and T20-60 with thermally conductive SiO2 inclusions. The measurements were performed by the steady-state method in the temperature range of 55–120 K for the longitudinal and transverse orientations of the samples, which allows evaluating the thermal conductivity anisotropy of the HTS assemblies. A method is proposed for determining the intrinsic thermal conductivity of the bonding layer from the difference in thermal resistances of soldered and glued samples of the same configuration, excluding the contribution of the tapes and the systematic component of the measurement setup. The thermal conductivity of the adhesive layers increases in the investigated temperature range from 0.45 to 0.77 W/(m·K). It is shown that the adhesive compounds TO-29-2 and T20-60 are equivalent in intrinsic thermal conductivity, and the difference in thermal conductivity of the assemblies is determined by the thickness of the adhesive layer. The measurement results of the longitudinal samples indicate that when attaching the stack by its end face, the thermal resistance is limited by the mounting joint rather than the conductor. The obtained values of the thermal resistance of the joints can be used to calculate assemblies of arbitrary configuration and to model the thermal stabilization of HTS devices.
Keywords: thermal conductivity; HTS tapes; HTS assemblies; adhesive compounds; thermally conductive additives; adhesive joints; thermally conductive compound; thermal resistance; thermal stabilization.
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