MoS2 Interactions with 1.5 eV Atomic Oxygen

1988 ◽  
Vol 140 ◽  
Author(s):  
J.A. Martin ◽  
J.B. Cross ◽  
L.E. Pope
Keyword(s):  
Oxide Layer ◽  
Atomic Oxygen ◽  
Diffusion Rate ◽  
Low Earth Orbit ◽  
Earth Orbit ◽  
Reaction Products ◽  
Crystallite Orientation ◽  
Protective Oxide ◽  
Protective Oxide Layer ◽  
Degree Of Oxidation

AbstractExposures of MoS2 to 1.5 eV atomic oxygen in an anhydrous environment reveal that the degree of oxidation is essentially independent of crystallite orientation and thesurface adsorbed reaction products are MoO3 and MoO2. A mixture ofoxides and sulfide exist over a depth of about 90 Å and this layer has a low diffusion rate for oxygen. It is concluded that a protective oxide layer will form on MoS2 upon exposure to the atomic-oxygen-rich environment of low earth orbit.

Leveling Coatings for Reducing Atomic Oxygen Defect Density in Graphite Fiber-Epoxy Composites

1994 ◽  
Vol 37 (3) ◽  
pp. 26-31
Author(s):  
D. Jaworske ◽  
K. de Groh ◽  
G. Podojil ◽  
T. McCollum ◽  
J. Anzic
Keyword(s):  
Atomic Oxygen ◽  
Defect Density ◽  
Protective Coatings ◽  
Protective Layer ◽  
Oxide Coating ◽  
Low Earth Orbit ◽  
Earth Orbit ◽  
Protective Oxide ◽  
Low Viscosity ◽  
Defect Sites

Pinholes or other defect sites in a protective oxide coating provide pathways for atomic oxygen in low-Earth orbit to reach underlying material. Onc concept for enhancing the lifetime of materials in low-Earth orbit is to apply a leveling coating to the material prior to applying any reflective and protective coatings. Using a surface-tension-leveling coating concept, a low-viscosity epoxy was applied to the surface of several composite coupons. A protective layer of 1000 Å of SiO2 was deposited on top of the leveling coating, and the coupons were exposed to an atomic oxygen environment in a plasma asher. Pinhole populations per unit area were estimated by counting the number of undercut sites observed by scanning electron microscopy. Defect density values of 180,000 defects/cm2 were reduced to about 1000 defects/cm2 as a result of the applied leveling coating. These improvements occur at a mass penalty of about 2.5 mg/cm2.

scholarly journals The Effect of Low Earth Orbit Atomic Oxygen Exposure on Phenylphosphine Oxide-Containing Polymers

2000 ◽  
Vol 12 (1) ◽  
pp. 43-52 ◽  
Author(s):  
John W Connell
Keyword(s):  
Thin Film ◽  
Atomic Oxygen ◽  
Low Earth Orbit ◽  
Space Environment ◽  
Earth Orbit ◽  
Cooperative Effort ◽  
Flight Experiment ◽  
Oxygen Exposure ◽  
Atomic Oxygen Exposure ◽  
Phenylphosphine Oxide

Thin films of phenylphosphine oxide-containing polymers were exposed to low Earth orbit aboard a space shuttle flight (STS-85) as part of flight experiment designated Evaluation of Space Environment and Effects on Materials (ESEM). This flight experiment was a cooperative effort between the NASA Langley Research Center (LaRC) and the National Space Development Agency of Japan (NASDA). The thin-film samples described herein were part of an atomic oxygen exposure (AOE) experiment and were exposed to primarily atomic oxygen (∼1×1019 atoms cm−2). The thin-film samples consisted of three phosphine oxide-containing polymers (arylene ether, benzimidazole and imide). Based on post-flight analyses using atomic force microscopy, x-ray photo-electron spectroscopy and weight loss data, it was found that the exposure of these materials to atomic oxygen (AO) produces a phosphorus oxide layer on the surface of the samples. Earlier work has shown that this layer provides a barrier towards further attack by AO. Consequently, these materials do not exhibit linear erosion rates which is in contrast with most organic polymers. Qualitatively, the results obtained from these analyses compare favourably with those obtained from samples exposed to AO and/or an oxygen plasma in ground-based exposure experiments. The results of the low Earth orbit AO exposure on these materials will be compared with those of ground-based exposure to AO.

Concentration of atomic oxygen in low earth orbit and in the laboratory for use in high quality oxide thin film growth

1998 ◽  
Author(s):  
J. A. Schultz ◽  
K. Eipers-Smith ◽  
K. Waters ◽  
S. Schultz ◽  
M. Sterling ◽  
...  
Keyword(s):  
Thin Film ◽  
Atomic Oxygen ◽  
Film Growth ◽  
Low Earth Orbit ◽  
Thin Film Growth ◽  
Oxide Thin Film ◽  
Earth Orbit ◽  
High Quality

Atomic Oxygen Plasma Effects on Cvd Deposited Diamond-Like Carbon Films

1991 ◽  
Vol 236 ◽  
Author(s):  
Jeffrey S. Hale ◽  
R.A. Synowicki ◽  
S. Nafis ◽  
John A. Woollam
Keyword(s):  
Atomic Oxygen ◽  
Moisture Absorption ◽  
Crystalline Silicon ◽  
Carbon Films ◽  
Fused Silica ◽  
Low Earth Orbit ◽  
Index Of Refraction ◽  
Earth Orbit ◽  
Diamond Like Carbon ◽  
Space Flights

AbstractCVD deposited diamond-like carbon (DLC) films have been studied for possible use as a secondary standard for Low Earth Orbit materials degradation. Samples of various thicknesses have been exposed to a simulated Low Earth Orbit atomic oxygen (AO) environment using a plasma asher. Mass loss measurements indicate that DLC degrades at a rate of 0.7 mg/hr which is two to three times the rate of currently used Kapton samples which degrade at a rate of.3 mg/hr. Thickness measurements show that DLC thins at a rate of 77 Angstroms/min. Since DLC is not as susceptible to environmental factors such as moisture absorption, it could potentially provide more accurate measurements of AO fluence on short space flights. Adhesion of DLC films to both fused silica and crystalline silicon substrates has been studied under thermal cycling conditions. Film adhesion to fused silica can be enhanced by sputtering a thin layer of silicon dioxide onto the substrate prior to deposition. In addition to the above, the index of refraction and extinction coefficient of various thicknesses of DLC films has been characterized by Variable Angle Spectroscopic Ellipsometry.

A Magnetically Filtered Atomic Oxygen Plasma Source for Low-Earth-Orbit Simulation

2021 ◽  
pp. 1-10
Author(s):  
Carlos A. Maldonado ◽  
Andrew D. Ketsdever ◽  
John D. Williams
Keyword(s):  
Atomic Oxygen ◽  
Oxygen Plasma ◽  
Plasma Source ◽  
Low Earth Orbit ◽  
Earth Orbit
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