Environmental Testing of Thermal Control Materials at Elevated Temperature and Intense Ultraviolet Radiation

Heltzel, Stan; Semprimoschnig, Christopher; Eesbeek, Marc van

doi:10.2514/1.31892

Cited by 13 publications

(11 citation statements)

References 1 publication

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“…Decomposition of organic components, however, is not deemed to be favorable for the thermal stability. Further assessment of thermal endurance of silicate paints by TGA is presented in Heltzel et al [3]. Figure 4 shows weight loss during isothermal exposure at 350 1 C comparing two thin (25 1m) polyimide foils of Kapton HN and Upilex S. By conditioning the samples in the TGA at elevated temperature the effects of water desorption are excluded, since these are not of concern.…”

Section: Thermogravimetric Analysis (Tga)mentioning

confidence: 99%

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Investigation of the Degradation of Thermal Control Materials by Thermal Analysis

Heltzel

Semprimoschnig

Eesbeek

2008

High Performance Polymers

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Thermal analysis is the name of a collection of techniques that investigates material properties as a function of temperature. Four main techniques which all look at specific material properties are differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), thermomechnical analysis (TMA) and dynamic mechanical analysis (DMA). The commercially available polyimide foils Kapton HN and Upilex S are often used as external thermal control material on spacecraft. For missions to the inner part of the solar system, these materials need to withstand an elevated service temperature in combination with high intensity solar radiation, such as UV and protons. The thermal stability of Kapton and Upilex has been investigated at around 250 1 C for a mission to Venus and at 350 1 C for a mission to Mercury. Samples were aged at representative temperature levels, also in combination with high intensity UV and proton radiation. It was found that TMA and DMA revealed, in good detail, the environmental effects of the behavior of the materials. Both foils are known to be thermally stable materials. Assessment by TGA and kinetic modeling indicates a better stability of Upilex at 350 1 C. The DMA experiments of foils aged at 350 1 C for up to 3580 h prove that the glass transition of Kapton is largely affected and almost completely disappears. Upilex is also affected but remains more stable. The TMA assessment revealed annealing of residual stresses at elevated temperature that cause (partial) shrinking of the foils. Ageing at around 250 1 C causes such annealing besides other more subtle changes. The added irradiation to high intensity UV and protons does not cause significant changes compared to thermal ageing alone. The DMA results are in good agreement with the TMA. The behavior of Upilex is deemed to be somewhat less affected by the environmental testing than Kapton.

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Section: Thermogravimetric Analysis (Tga)mentioning

confidence: 99%

“…For reliable assessment of thermal endurance, this technique is always correlated with long-term isothermal ageing under high vacuum [3].…”

Section: Kinetic Modelingmentioning

confidence: 99%

Investigation of the Degradation of Thermal Control Materials by Thermal Analysis

Heltzel

Semprimoschnig

Eesbeek

2008

High Performance Polymers

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“…It is known from many of these evaluation tests that particle and electromagnetic radiation can significantly degrade materials (see e.g. Lura et al, 1997;Heltzel et al, 2009;Sharma & Sridhara, 2012).…”

Section: Introductionmentioning

confidence: 99%

Degradation of metallic surfaces under space conditions, with particular emphasis on Hydrogen recombination processes

Sznajder

Geppert

Dudek

2015

Advances in Space Research

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The widespread use of metallic structures in space technology brings risk of degradation which occurs under space conditions. New types of materials dedicated for space applications, that have been developed in the last decade, are in majority not well tested for different space mission scenarios. Very little is known how material degradation may affect the stability and functionality of space vehicles and devices during long term space missions.Our aim is to predict how the solar wind and electromagnetic radiation degrade metallic structures. Therefore both experimental and theoretical studies of material degradation under space conditions have been performed. The studies are accomplished at German Aerospace Center (DLR) in Bremen (Germany) and University of Zielona Góra (Poland).The paper presents the results of the theoretical part of those studies. It is proposed that metal bubbles filled with Hydrogen molecular gas, resulting from recombination of the metal free electrons and the solar protons, are formed on the irradiated surfaces. A thermodynamic model of bubble formation has been developed. We study the creation process of H 2 -bubbles as function of, inter alia, the metal temperature, proton dose and energy. Our model has been verified by irradiation experiments completed at the DLR facility in Bremen.Consequences of the bubble formation are changes of the physical and thermo-optical properties of such degraded metals. We show that a high surface density of bubbles (up to 10 8 cm −2 ) with a typical bubble diameter of ∼ 0.4µm will cause a significant increase of the metallic surface roughness. This may have serious consequences to any space mission.Changes in the thermo-optical properties of metallic foils are especially important for the solar sail propulsion technology because its efficiency depends on the effective momentum transfer from the solar photons onto the sail structure. This transfer is proportional to the reflectivity of a sail. Therefore, the propulsion abilities of sail material will be affected by the growing population of the molecular Hydrogen bubbles on metallic foil surfaces.

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“…Porém, a degradação ocorre oriunda dos contaminantes provindos da "degaseificação" de orgânicos voláteis que são exauridos do satélite ou do foguete no estágio de posicionamento do satélite (2,3,5) . O mecanismo de degradação ainda não é bem conhecido, porém está comprovado que esse efeito causa o aumento de absortividade solar nestes radiadores tipo espelho.…”

Section: Introductionunclassified

Testes de degradação por foto deposição de um refletor solar óptico para controle térmico de satélites

Boato

Garcia

Santos

et al. 2015

RBAV

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Environmental Testing of Thermal Control Materials at Elevated Temperature and Intense Ultraviolet Radiation

Cited by 13 publications

References 1 publication

Investigation of the Degradation of Thermal Control Materials by Thermal Analysis

Investigation of the Degradation of Thermal Control Materials by Thermal Analysis

Degradation of metallic surfaces under space conditions, with particular emphasis on Hydrogen recombination processes

Testes de degradação por foto deposição de um refletor solar óptico para controle térmico de satélites

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