Thermal Interface Materials
Thermal Pads, Greases, and Gap Fillers
Thermal interface materials—including silicone greases, elastomeric pads, phase-change materials, and indium foils—fill microscopic voids between mating surfaces to minimize contact resistance between equipment and thermal control cold plates or heat pipes. Lunar deployment is constrained by the vacuum and radiation environment. Outgassing from silicone formulations can contaminate adjacent optical and cryogenic surfaces. Over decades of operation, these materials also suffer from pump-out and dry-out degradation, necessitating vacuum- and radiation-compatible material selection and robotic reapplication during maintenance.
Materials filling gaps between mating surfaces to minimize thermal contact resistance
Purpose
Ensure efficient heat transfer between equipment and thermal control cold plates/heat pipes
Context
Child of L2-TCS-INTF in the Active Thermal Control System
Principles
- ▸Thermal greases (silicone-based) fill microscopic surface irregularities reducing contact resistance
- ▸Thermal pads (compliant elastomeric) accommodate tolerance stack-up while conducting heat
- ▸Phase-change TIMs melt during operation filling voids at operating temperature
- ▸Indium foil provides metallic thermal interface for highest conductivity applications
Typical implementations
- ▸Dow Corning (Dow) TC-5022 thermal grease (space heritage)
- ▸Bergquist/Henkel Gap Pad thermal pads
- ▸Indium Corporation thermal interface foils
- ▸Honeywell PTM7950 phase-change TIM
Lunar considerations
- ▸Outgassing of silicone-based TIMs can contaminate optical and cryogenic surfaces
- ▸TIM degradation (pump-out, dry-out) over decades degrades thermal performance
- ▸Must select TIMs compatible with vacuum and radiation environment
- ▸Robotic TIM reapplication during maintenance may be needed
Specifications
Functional
| primary function | Materials filling gaps between mating surfaces to minimize thermal contact resistance |
Physical
| materials | Silicone thermal grease, Indium foil, Gap pad elastomers, Phase-change materials |
Interfaces
Provides
- Low-resistance thermal coupling between equipment and TCS
Requires
- Replacement TIM materials for maintenance
Cite this entry
Lunar Ark Codex. "Thermal Interface Materials" (L3-TCS-INTF-TIM). Retrieved 10 September 2026, from https://lunarark.com/entry/L3-TCS-INTF-TIM
Licensed CC-BY-SA 4.0. You may reuse and adapt this entry with attribution, under the same licence.