Thermal conductance of pressed metallic contacts augmented with indium foil or Apiezon grease at liquid helium temperatures

The thermal conductance of pressed contacts which have been augmented with indium foil or Apiezon-N™ grease has been measured over the temperature range 1.6–6.0 K, with applied forces from 22 to 670N. The sample pairs were fabricated from OFHC copper, 6061-T6 aluminium, free-machining brass and 304 stainless steel. Although the thermal conductance was found to increase with increasing applied contact force, the force dependence was less than in earlier work. The addition of indium foil or Apiezon grease between the contact surfaces resulted in an improvement over uncoated surfaces ranging from approximately a factor of 3 for stainless steel to an order of magnitude for copper contacts.