A study on degradation of germanium coating on Kapton used for spacecraft sunshield application

Abstract

a Sunshield membranes made of germanium-coated black polyimide (GBP) or Kapton are often used on the reflector/transmitter antenna of satellites for thermal control applications. However, the germanium top layer is prone to degrade during ground storage and implementation. Hence, vacuum/inert gas-sealed packaging is required for storing the membranes, followed by a staggered fabrication schedule as the shelf-life of the GBP is identified as only~6 months. In the present study, microstructural, thermo-optical, and electrical properties along with X-ray photoelectron spectroscopy (XPS) studies for evaluating oxidation states of the as-received and degraded GBP films have been investigated thoroughly. The radio frequency (RF) loss behavior of both the films has also been studied for S band (2.5-3.5 GHz), Ku band (10.5-14.5 GHz), and Ka band (30-35 GHz).

Coatings and Thin Films for Spacecraft Thermo‐Optical and Related Functional Applications

“…For germanium coatings on polyimide films, tests conducted at 50 °C and 97% relative humidity (RH) led to oxidative degradation and formation of large dark spots, as well as exposing parts of the polymer film . Similar studies were performed by Dey and co‐workers as part of their extensive project on degradation of germanium coating on kapton used for spacecraft sunshield application. In order to limit this degradation in sunshield for application on the communication satellite antenna, a nanoalumina coating deposited on top of the germanium coating was developed …”

Tailoring Ordered Mesoporous Titania Films via Introducing Germanium Nanocrystals for Enhanced Electron Transfer Photoanodes for Photovoltaic Applications

“…We find that three spectral components are necessary: one is located at a binding energy of ≈1217.3 eV and can be associated with elemental Ge, while the other two at higher binding energies of ≈1218.9 and ≈1220.0 eV are attributed to GeO and GeO 2 , respectively. [ 53,54 ] Thus, Ge, GeO 2 , as well as GeO are present in the nanocomposite films. The presence of GeO can be rationalized by considering that the reversible reaction (2GeO ↔ GeO 2 + Ge) might occur during thermal annealing at 500 °C, [ 55,56 ] in addition to the oxygen deficiency of the argon atmosphere annealing environment.…”

Investigation of long-term storage of space materials for future constellation missions: study of Braycote® 601 EF lubricant

“…Wide studies led by ESA [3] or Airbus [4], including hundreds of IOP Publishing doi:10.1088/1757-899X/1287/1/012011 2 samples stored for years, can also be pointed out. This LTS topic typically applies to all types of materials, from coatings and mirror which may degrade [5][6][7], to adhesive tapes which may lose adhesion or debond as a result of adhesive embrittlement, passing by CFRP structures [8], connectors [9], pyrotechnic igniter [10] and lubricants [11]. Among these last materials, Perfluoropolyether (PFPE) type lubricants and greases are common in space mechanism applications owing to their high thermal and chemical stability, as well as low outgassing properties.…”