Thermal conductivity of various CFRPs from 100 mK to 20 K

TL;DR

This work addresses the scarcity of cryogenic thermal-conductivity data for CFRPs by measuring nine CFRP samples across 100 mK to 20 K using a specialized cryogenic setup. The authors determine κ(T) by injecting controlled heat and fitting the data with a Callaway-type model $\kappa(T) = \frac{a T^3}{1 + b T^n}$, while accounting for an environmental heat term $\dot{Q}_0$ and radiative losses. Uncertainties are propagated via a Monte Carlo approach with 200 realizations. The results reveal strong dependence on fiber orientation and content, show an inflection below 1 K, and provide a practical κ(T) parametrization for designing cryogenic CFRP components, aligned with existing literature when material definitions match. This enables improved thermal modeling for future cryogenic space instruments.

Abstract

Carbon-fiber-reinforced polymers (CFRPs) are some of the most useful materials for building spacecraft and aerospace tools. They are especially valuable for systems that work at extremely cold (cryogenic) temperatures because they are strong, lightweight, and don't transfer heat easily. In this study, researchers measured how well heat moves through several different types of carbon fiber samples, specifically T300, T700, HS40, M55J, and IMA, at different fiber layouts and densities. These measurements were taken at ultra-cold temperatures ranging from 100 mK to 20 K. The team used a newly developed analysis method to calculate the thermal conductivity for each sample. Finally, they shared how each material behaved at different temperatures and compared their findings to previous research.

Figures (17)

• Figure 1: The instrumented sample was placed on the cold plate.
• Figure 2: Exploded view of a "linear" contact for both top and bottom thermometers. The choice of a linear contact was made to reduce the uncertainties of the length between the two thermometers.
• Figure 3: On top the contact for the heater to maximize the injected power into the sample, and on bottom the linear contact for the thermometry to limit the uncertainties of the length between the two thermometers.
• Figure 4: Exploded view of the interface design to thermally couple the heater and the sample.
• Figure 5: Mechanical design to anchor the sample on the cold plate of the cryostat. To ensure good thermal contact, the interface is a large surface between the sample and the copper gold-plated cold plate.