Coating surface - Beginning of Life
Enabling & Support

Near-Sun Mission Heat Shield Material Assessment

21/04/2017 299 views 1 likes
ESA / Enabling & Support / Space Engineering & Technology / Shaping the Future
 Programme:  TRP Workplan  Achieved TRL:  2-3
 Reference:  T224-001QT  Closure:  2016
 Contractor(s):  AAC (AT), CNRS (FR), TRAD (FR), Astrium (FR)

 
A first TRP activity investigated the materials potentially surviving the requirements of the PHOBOS mission; i.e. going down to 4 solar radii when placed as the outer surface of the primary heat shield. Two materials were identified i.e. Carbon and hexagonal boron nitride.

Objective(s)
The main objective of the study was to investigate the combination of the identified materials i.e. a carbon/carbon composite substrate and an hexagonal boron nitride coating under the harsh environment of a near sun mission (e.g. Phobos). 

Coating surface - End of Life
Coating surface - End of Life

Achievements and status
A system has been identified (based on Sigrabond Extraclean with Chemical Vapor Deposition Pyrolitic Boron Nitride) as suitable to survive the harsh mission environment . The system is stable at up to 2180K; above the  mission requirement (1750 K). The proton and UV irradiation tend to increase the a/e ratio. The coating is cracked but still adheres to the substrate.

Benefits
From a material point view there are no blocking points to use this material on the referenced mission.

Next steps
The processes required to scale up will need to be further investigated as well as the means to connect the CVD-pBN to the next layers of the heat-shield.

 

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