Predicting thermal contact resistance at cryogenic temperatures for spacecraft applications

Abstract

Extensive work has been done to predict thermal contact resistance (or thermal contact conductance) at room temperature; however only limited research has been conducted at cryogenic temperatures. The absence of experimental data is notable because of the many applications for spacecraft at low temperature. This paper presents thermal contact conductance measurements of pressed metal contacts in a vacuum environment near room temperature and at cryogenic temperatures (110 to 144 K). Contact pressures varied from 0.4 to 14 MPa. The materials used were chosen because of their applications within the aerospace industry: stainless steel (AISI304), aluminum (6061-T6), a low-expansion nickel-iron alloy (39% nickel), and beryllium. Existing theoretical correlations (an elastic contact model and a plastic contact model) are reviewed, and the temperature dependence of the relevant material properties is investigated to explain the results. The stainless-steel data are in good agreement with the elastic contact model, whereas the aluminum data do not agree well with either the elastic or the plastic contact model. Of particular interest are the results with beryllium that indicate the conductance may not always be directly proportional to the bulk thermal conductivity.