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Research Containing: Erosion

The Effect of Ash and Inorganic Pigment Fill on the Atomic Oxygen Erosion of Polymers and Paints

by on 9 June 2015in Technology Development & Demonstration No comment

Low atomic oxygen fluence (below 1×10(exp 20) atoms/sq cm) exposure of polymers and paints that have a small ash content and/or inorganic pigment fill does not cause a significant difference in erosion yield compared to unfilled (neat) polymers or paints. However, if the ash and/or inorganic pigment content is increased, the surface population of the inorganic content will begin to occupy a significant fraction of the surface area as the atomic oxygen exposure increases because the ash is not volatile and remains as a loosely attached surface layer. This results in a reduction of the flux of atomic oxygen reacting with the polymer and a reduction in the rate of erosion of the polymer remaining. This paper presents the results of ground laboratory and low Earth orbital (LEO) investigations to evaluate the fluence dependence of atomic oxygen erosion yields of polymers and paints having inorganic fill content.

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Effect of LEO Exposure on Aromatic Polymers Containing Phenylphosphine Oxide Groups

by on 9 June 2015in Physical Sciences No comment

As part of the Materials on The International Space Station Experiment (MISSE), aromatic polymers containing phenylphosphine oxide groups were exposed to low Earth orbit for ∼4 years. All of the aromatic polymers containing phenylphosphine oxide groups survived the exposure despite the high fluence of atomic oxygen that completely eroded other polymer films such as Kapton® and Mylar® of comparable or greater thickness. The samples were characterized for changes in physical properties, thermal/optical properties surface chemistry, and surface topography. The data from the polymer samples on MISSE were compared to samples from the same batch of material stored under ambient conditions on Earth. In addition, comparisons were made between the MISSE samples and those subjected to shorter term space flight exposures. The results of these analyses will be presented.

Related URLs:
http://scitation.aip.org/content/aip/proceeding/aipcp/10.1063/1.3076842

Ground‐Laboratory to In‐Space Atomic Oxygen Correlation for the PEACE Polymers

by on 9 June 2015in Physical Sciences No comment

The Materials International Space Station Experiment 2 (MISSE 2) Polymer Erosion and Contamination Experiment (PEACE) polymers were exposed to the environment of low Earth orbit (LEO) for 3.95 years from 2001 to 2005. There were forty‐one different PEACE polymers, which were flown on the exterior of the International Space Station (ISS) in order to determine their atomic oxygen erosion yields. In LEO, atomic oxygen is an environmental durability threat, particularly for long duration mission exposures. Although space flight experiments, such as the MISSE 2 PEACE experiment, are ideal for determining LEO environmental durability of spacecraft materials, ground‐laboratory testing is often relied upon for durability evaluation and prediction. Unfortunately, significant differences exist between LEO atomic oxygen exposure and atomic oxygen exposure in ground‐laboratory facilities. These differences include variations in species, energies, thermal exposures and radiation exposures, all of which may result in different reactions and erosion rates. In an effort to improve the accuracy of ground‐based durability testing, ground‐laboratory to in‐space atomic oxygen correlation experiments have been conducted. In these tests, the atomic oxygen erosion yields of the PEACE polymers were determined relative to Kapton H using a radio‐frequency (RF) plasma asher (operated on air). The asher erosion yields were compared to the MISSE 2 PEACE erosion yields to determine the correlation between erosion rates in the two environments. This paper provides a summary of the MISSE 2 PEACE experiment; it reviews the specific polymers tested as well as the techniques used to determine erosion yield in the asher, and it provides a correlation between the space and ground‐laboratory erosion yield values. Using the PEACE polymers’ asher to in‐space erosion yield ratios will allow more accurate in‐space materials performance predictions to be made based on plasma asher durability evaluation.

Related URLs:
http://scitation.aip.org/content/aip/proceeding/aipcp/10.1063/1.3076865

An Investigation of Stress Dependent Atomic Oxygen Erosion of Black Kapton Observed on MISSE 6

by on 9 June 2015in Physical Sciences No comment

Black Kapton XC polyimide was flown as part of the Polymer Film Tensile Experiment (PFTE) on Materials International Space Station Experiment 6 (MISSE 6). The purpose of the experiment was to expose a variety of polymer films, typical of those used for thermal control blankets or supporting membranes on Earth orbiting spacecraft, to the low Earth orbital (LEO) environment under both relaxed and tension conditions. Black Kapton XC under tensile stress experienced a higher erosion rate during exposure in LEO than the same material that was flown in a relaxed condition. Testing conducted to determine the magnitude of the stress and erosion dependence using a ground-based thermal energy atomic oxygen plasma showed a slight dependence of erosion yield on stress for Kapton HN and Black Kapton XC, but not to the extent observed on MISSE 6. More testing is needed to isolate the factors present in LEO that cause stress dependent erosion.

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The Materials on International Space Station Experiment (MISSE): First Results from MSFC Investigations

by on 9 June 2015in Physical Sciences No comment

Hundreds of material samples were passively exposed to the space environment for nearly four years as part of the Materials on International Space Station Experiment (MISSE). The experiment was planned for one year of exposure, but its return was delayed by the Columbia accident and subsequent grounding of the Space Shuttle fleet. The experiment was attached externally to the Quest Airlock. Atomic oxygen fluence and ultraviolet radiation dose varied across the experiment because of shadowing and space station orientation. Over a hundred meteoroid/space debris impacts were found. Many polymer film samples were completely eroded by atomic oxygen. Some particulate contamination was noted, but black light inspection and the transmission measurements of magnesium fluoride windows indicated that molecular contaminant deposition was limited. Optical property changes in thermal control materials are discussed.

Related URLs:
http://dx.doi.org/10.2514/6.2006-472

MISSE 2 PEACE Polymers Erosion Morphology Studies

by on 9 June 2015in Physical Sciences No comment

Forty-one different polymer samples, collectively called the Polymer Erosion and Contamination Experiment (PEACE) Polymers, were exposed to the low Earth orbit (LEO) environment on the exterior of the International Space Station (ISS) for nearly four years as part of the Materials International Space Station Experiment 2 (MISSE 2). The objective of the PEACE Polymers experiment was to determine the atomic oxygen erosion yield of a wide variety of polymeric materials after long term exposure to the space environment. The polymers range from those commonly used for spacecraft applications to more recently developed polymers. Additional polymers, not considered for spacecraft applications, were included to explore erosion yield dependence upon chemical composition. The polymers were typically in thin-film form (25 to 500 μm thick) and depending on the polymer thickness and estimated erosion yield, stacking of numerous thin film sample layers was often necessary. Several thick single layer materials, such as epoxy and pyrolytic graphite, were also included. The PEACE Polymers experiment was flown in MISSE Passive Experiment Container 2 (PEC 2) on the exterior of the ISS Quest Airlock and was exposed to ram atomic oxygen, along with solar and charged particle radiation, for the majority of the mission; hence the polymers typically developed very diffuse textures. The average atomic oxygen fluence was 8.43 x 1021 atoms/cm2. This paper documents the erosion morphology of numerous MISSE 2 PEACE polymer samples. Erosion cone structures were examined for high and low erosion yield samples. Also examined were the erosion characteristics for thin film polymers eroded through several layers. Of particular interest was documentation of the erosion of a thin film polymer outer layer at cone valleys, and the corresponding erosion morphology of the underlying layer. This information is relevant to the durability of materials and components on spacecraft that are protected by thin film polymers. The MISSE 2 PEACE Polymers experiment is unique because it has the widest variety of polymers flown collectively in LEO for a long duration and was exposed to an unusually clean LEO spacecraft environment. This paper provides high fluence ram atomic oxygen erosion morphology data applicable to spacecraft durability.

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MISSE PEACE Polymers Atomic Oxygen Erosion Results

by on 9 June 2015in Physical Sciences No comment

Forty-one different polymer samples, collectively called the Polymer Erosion and Contamination Experiment (PEACE) Polymers, have been exposed to the low Earth orbit (LEO) environment on the exterior of the International Space Station (ISS) for nearly 4 years as part of Materials International Space Station Experiment 2 (MISSE 2). The objective of the PEACE Polymers experiment was to determine the atomic oxygen erosion yield of a wide variety of polymeric materials after long term exposure to the space environment. The polymers range from those commonly used for spacecraft applications, such as Teflon (DuPont) FEP, to more recently developed polymers, such as high temperature polyimide PMR (polymerization of monomer reactants). Additional polymers were included to explore erosion yield dependence upon chemical composition. The MISSE PEACE Polymers experiment was flown in MISSE Passive Experiment Carrier 2 (PEC 2), tray 1, on the exterior of the ISS Quest Airlock and was exposed to atomic oxygen along with solar and charged particle radiation. MISSE 2 was successfully retrieved during a space walk on July 30, 2005, during Discovery s STS-114 Return to Flight mission. Details on the specific polymers flown, flight sample fabrication, pre-flight and post-flight characterization techniques, and atomic oxygen fluence calculations are discussed along with a summary of the atomic oxygen erosion yield results. The MISSE 2 PEACE Polymers experiment is unique because it has the widest variety of polymers flown in LEO for a long duration and provides extremely valuable erosion yield data for spacecraft design purposes.

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NASA Glenn Research Center's Materials International Space Station Experiments (MISSE 1-7)

by on 9 June 2015in Physical Sciences No comment

NASA Glenn Research Center (Glenn) has 39 individual materials flight experiments (>540 samples) flown as part of the Materials International Space Station Experiment (MISSE) to address long duration environmental durability of spacecraft materials in low Earth orbit (LEO). MISSE is a series of materials flight experiments consisting of trays, called Passive Experiment Carriers (PECs) that are exposed to the space environment on the exterior of the International Space Station (ISS). MISSE 1-5 have been successfully flown and retrieved and were exposed to the space environment from one to four years. MISSE 6A & 6B were deployed during the STS-123 shuttle mission in March 2008, and MISSE 7A & 7B are being prepared for launch in 2009. The Glenn MISSE experiments address atomic oxygen (AO) effects such as erosion and undercutting of polymers, AO scattering, stress effects on AO erosion, and in-situ AO fluence monitoring. Experiments also address solar radiation effects such as radiation induced polymer shrinkage, stress effects on radiation degradation of polymers, and radiation degradation of indium tin oxide (ITO) coatings and spacesuit fabrics. Additional experiments address combined AO and solar radiation effects on thermal control films, paints and cermet coatings. Experiments with Orion Crew Exploration Vehicle (CEV) seals and UltraFlex solar array materials are also being flown. Several experiments were designed to provide ground-facility to in-space calibration data thus enabling more accurate in-space performance predictions based on ground-laboratory testing. This paper provides an overview of Glenn s MISSE 1-7 flight experiments along with a summary of results from Glenn s MISSE 1 & 2 experiments.

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MISSE 2 PEACE Polymers Atomic Oxygen Erosion Experiment on the International Space Station

by on 9 June 2015in Physical Sciences No comment

Forty-one different polymer samples, collectively called the Polymer Erosion and Contamination Experiment (PEACE) Polymers, were exposed to the low Earth orbit (LEO) environment on the exterior of the International Space Station (ISS) for nearly 4 years as part of Materials International Space Station Experiment 2 (MISSE 2). The objective of the PEACE Polymers experiment was to determine the atomic oxygen erosion yield of a wide variety of polymeric materials after long-term exposure to the space environment. The polymers range from those commonly used for spacecraft applications, such as Teflon ® FEP, to more recently developed polymers, such as high temperature polyimide PMR (polymerization of monomer reactants). Additional polymers were included to explore erosion yield dependence upon chemical composition. The MISSE PEACE Polymers experiment was flown in MISSE Passive Experiment Carrier 2 (PEC 2), tray 1, attached to the exterior of the ISS Quest Airlock. It was exposed to atomic oxygen along with solar and charged particle radiation. MISSE 2 was successfully retrieved during a space walk on July 30, 2005 during Discovery's STS-114 Return to Flight mission. Details on the specific polymers flown, flight sample fabrication, pre-flight and post-flight characterization techniques, and atomic oxygen fluence calculations are discussed along with a summary of the atomic oxygen erosion yield results. The MISSE 2 PEACE Polymers experiment is unique because it has the widest variety of polymers flown in LEO for a long duration and was exposed to an unusually clean LEO spacecraft environment. This experiment provides extremely valuable erosion yield data for spacecraft design purposes.

Related URLs:
http://hip.sagepub.com/content/20/4-5/388.abstract

Space Environment Exposure of Polymer Films on the Materials International Space Station Experiment: Results from MISSE 1 and MISSE 2

by on 9 June 2015in Physical Sciences No comment

A total of thirty-one samples were included in the National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) Polymer Film Thermal Control (PFTC) and Gossamer Materials experiments, which were exposed to the low Earth orbit environment for nearly 4 years on the exterior of the International Space Station (ISS) as part of the Materials International Space Station Experiment (MISSE 1 and MISSE 2). This paper describes objectives, materials, and characterizations for the MISSE 1 and MISSE 2 GRC PFTC and Gossamer Materials samples. Samples included films of polyimides, fluorinated polyimides, and Teflon® fluorinated ethylene propylene (FEP) with and without second-surface metalized layers and/or surface coatings. Films of polyphenylene benzobisoxazole (PBO) and a polyarylene ether benzimidazole (TOR-LM TM) were also included. Polymer film samples were examined post-flight for changes in mechanical and optical properties. The environment in which the samples were located was characterized through analysis of sapphire contamination witness samples and samples dedicated to atomic oxygen (AO) erosion measurements. Results of the analyses of the PFTC and Gossamer Materials experiments are discussed.

Related URLs:
http://hip.sagepub.com/content/20/4-5/371.abstract