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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 667 records · Page 37
All sourcesNASA NTRSDOE OSTI
NASA NTRS1989

Contamination removal using various solvents and methodologies

Critical and non-critical bonding surfaces must be kept free of contamination that may cause potential unbonds. For example, an aft-dome section of a redesigned solid rocket motor that had been contaminated with hydraulic oil did not appear to be sufficiently cleaned when inspected by the optically stimulated electron emission process (Con Scan) after it had been cleaned using a hand double wipe cleaning method. As a result, current and new cleaning methodologies as well as solvent capability in removing various contaminant materials were reviewed and testing was performed. Bonding studies were also done to verify that the cleaning methods used in removing contaminants provide an acceptable bonding surface. The removal of contaminants from a metal surface and the strength of subsequent bonds were tested using the Martin Marietta and double-wipe cleaning methods. Results are reported.

Jeppsen, J. C.↗
NASA NTRS1974

Payload/orbiter contamination control requirement study, volume 2, exhibit A

The computer printout data generated during the Payload/Orbiter Contamination Control Requirement Study are presented. The computer listings of the input surface data matrices, the viewfactor data matrices, and the geometric relationship data matrices for the three orbiter/spacelab configurations analyzed in this study are given. These configurations have been broken up into the geometrical surfaces and nodes necessary to define the principal critical surfaces whether they are contaminant sources, experimental surfaces, or operational surfaces. A numbering scheme was established based upon nodal numbers that relates the various spacelab surfaces to a specific surface material or function. This numbering system was developed for the spacelab configurations such that future extension to a surface mapping capability could be developed as required.

Bareiss, L. E.↗
NASA NTRS1990

Nylon and teflon scribe effect on NBR to Chemlok 233 and NBR to NBR bond interfaces

A study was requested by Manufacturing Engineering to determine what effects marking with nylon (6/6) and Teflon scribes may have on subsequent bonding. Witness panel bond specimens were fabricated by the development lab to test both acrylonitrile butadiene rubber (NBR) to Chemlok and NBR to NBR after controlled exposure. The nylon rod used as a scribe tool demonstrates virtually no bond deterioration when used to scribe lines on either the Chemlok to NBR surfaces or the NBR to NBR interface. Lab test results indicate that the nylon rod-exposed samples produce tensile and peel values very similar to the control samples and the Teflon exposed samples produce tensile and peel values much lower than the control samples. Visual observation of the failure surfaces of the tested samples shows that Teflon scribing produces an obvious contamination to the surface and the nylon produces no effect. Photographs of test samples are provided. It is concluded that Teflon stock used as a scribe tool on a Chemlok 233 to NBR surface or an NBR to NBR surface has a detrimental effect on the bond integrity on either of these bond interfaces. Therefore, it is recommended that the nylon rod continue to be used where a scribe line is required in the redesigned solid rocket motor segment insulation layup operations. The use of Teflon scribes should not be considered.

Jensen, S. K.↗
NASA NTRS1993

Evidence for dust contamination on the VETA-1 mirror surface

Relative surface brightness data from the VETA-1 test displayed an energy dependence which was inconsistent with models which assume surface roughness is the only cause of scattering. A means of separating an in-plane component of scattering caused by surface roughness from an azimuthally symmetric component, which is expected from dust, was afforded by images taken while only single quarters of the mirror surface were exposed. In this case, in-plane scattered X-rays should populate only opposing 90 deg azimuthal quadrants of an image centered on the focal point. As such, this approach is a novel, high sensitivity test for detecting extremely small (about 10 exp -5) fractional dust coverage on X-ray optics. Comparison of in-plane and out-of-plane quadrants in these tests indicated that most of the scattered data were azimuthally symmetric, and that the symmetric component was enhanced at lower energies. Both results support a model which invokes the wing scan results with a combination of dust and surface roughness induced scattering. The extent to which parameters such as the mirror surface roughness, dust size distribution, spatial distribution, and density may be determined using this approach is also discussed.

Kolodziejeczak, J. J.↗
NASA NTRS1990

Holographic Reticle

Holographic reticle proposed for use in nondestructive evaluation of surface irregularities. Extends inspection capability to include measurements of depth. Surfaces inspected without contamination, damage, or costly disassembly. Provides valuable information difficult to obtain. For example, surface defects as corrosion and porosity, as well as propagation of cracks, measured accurately. Roughness, wear, and plating thickness also measured. Also used to determine quality of microcircuits.

Henn, Edward A.↗
DOE OSTI2020

Surface reservoirs dominate dynamic gas-surface partitioning of many indoor air constituents

Human health is affected by indoor air quality. One distinctive aspect of the indoor environment is its very large surface area that acts as a poorly characterized sink and source of gas-phase chemicals. In this work, air-surface interactions of 19 common indoor air contaminants with diverse properties and sources were monitored in a house using fast-response, on-line mass spectrometric and spectroscopic methods. Enhanced-ventilation experiments demonstrate that most of the contaminants reside in the surface reservoirs and not, as expected, in the gas phase. They participate in rapid air-surface partitioning that is much faster than air exchange. Phase distribution calculations are consistent with the observations when assuming simultaneous equilibria between air and large weakly polar and polar absorptive surface reservoirs, with acid-base dissociation in the polar reservoir. Chemical exposure assessments must account for the finding that contaminants that are fully volatile under outdoor air conditions instead behave as semivolatile compounds indoors.

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTAN↗
DOE OSTI2020

Radiation detectors employing contemporaneous detection and decontamination

Radiation detectors and methods of using the radiation detectors that provide a route for surface decontamination during use are described. The detectors utilize light illumination of an internal surface during use. Light is in the longer UV to near-infrared spectra and desorbs contamination from internal surfaces of radiation detectors. The methods can be carried out while the detectors are in operation, preventing the appearance of the negative effects of radioactive and non-radioactive contamination during a detection regime and following a detection regime.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2022

Radiation detectors employing contemporaneous detection and decontamination

Radiation detectors and methods of using the radiation detectors that provide a route for surface decontamination during use are described. The detectors utilize light illumination of an internal surface during use. Light is in the longer UV-to-near-infrared spectra and desorbs contamination from internal surfaces of radiation detectors. The methods can be carried out while the detectors are in operation, preventing the appearance of the negative effects of radioactive and non-radioactive contamination during a detection regime and following a detection regime.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2022

Electrical-Discharge-Machining Contamination Removal from Metal Additively Manufactured Components

The use of an electrochemical dissolution process is shown to remove the recast layer contamination from the surfaces of electrical-discharge-machining cut components, as well as the interior exposed surfaces of the structure. The solution chemistry, cell potential, and exposure time are all relevant interdependent variables. Optimization of the electrode geometry should be made for each type of component. For the case of Cu-Zn recast contamination of 300-series alloy components, surface composition analysis indicates that complete electrochemical dissolution is achieved using a dilute solution of nitric acid (HNO 3 ). For example, electrochemical dissolution of the Cu-Zn recast is accomplished at 1.2 V cell potential using a 20% nitric solution and an exposure time of 4 h. The use of a nitric acid bath was specifically chosen since it’s chemically compatible and will not degrade the host alloy or the component. In sum, an electrochemically driven dissolution process can be tailored to remove of the recast contamination without affecting the integrity of the host component structure and its dimensional tolerances.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Stainless Steel Coating Test Report

A process was developed to coat 316L stainless steel pieces having very low levels of fixed contamination on their surface (~100 dpm/100 cm²). The coating process served to significantly decrease the likelihood of any fixed contamination becoming loose contamination due to physical shocks. Prior to coating, the stainless steel was etched with a commercial methane sulfonic acid (MSA) solution in a heated ultrasonic bath, rinsed with deionized water, cleaned with a basic detergent solution, and then rinsed with deionized water. The MSA etched the surface of the stainless-steel pieces, creating a more favorable surface on which the coating could adhere. Due to the short timeline of the project, only commercially available clear coating products were considered. The clear coating had to be wear-resistant, shock resistant, radiation resistant, and have high adhesion to the surface of the stainless steel. Adhesion of coatings to stainless steel is notoriously difficult. A commercial, high molecular weight polymer coating was found that met these requirements. The adhesion properties of this coating to stainless steel are very good, and are significantly improved by the etching process. The etching process results in a higher surface area that is free of debris and other residues, making the surface much more wetable, and at the same time creating a favorable surface topography for adhesion. The polymer in its uncured form is a low viscosity liquid. It can be applied by brush or pipette, and it cures in air alone, but heat is required to speed up curing and attain the highest performance of the cured polymer. As the project progressed, the project team became interested in the composition of the selected commercial polymer coating, and in ways that this polymer coating could be made more wear resistant and potentially more radiation resistant. Nano-particle addition was chosen as the preferred way to achieve higher performance. Therefore, a series of tests were planned and performed. This report summarizes these tests, and presents the results.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Background identification in cryogenic calorimeters through $\alpha -\alpha$ delayed coincidences

Localization and modeling of radioactive contaminations is a challenge that ultra-low background experiments are constantly facing. These are fundamental steps both to extract scientific results and to further reduce the background of the detectors. Here we present an innovative technique based on the analysis of $\alpha -\alpha$ delayed coincidences in 232 Th and 238 U decay chains, developed to investigate the contaminations of the ZnSe crystals in the CUPID-0 experiment. This method allows to disentangle surface and bulk contaminations of the detectors relying on the different probability to tag delayed coincidences as function of the $\alpha$ decay position.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS1992

Analysis of Interplanetary Dust Experiment Detectors and Other Witness Plates

The development of analytical procedures for identifying the chemical composition of residue from impacts that occurred on the Interplanetary Dust Experiment (IDE) detectors during the flight of Long Duration Exposure Facility (LDEF) and the carrying out of actual analysis on IDE detectors and other witness plates are discussed. Two papers on the following topics are presented: (1) experimental analysis of hypervelocity microparticle impact sites on IDE sensor surfaces; and (2) contaminant interfaces with secondary Ion Mass Spectrometer (SIMS) analysis of microparticle impactor residues on LDEF surfaces.

Griffis, D. P.↗
NASA NTRS2001

Solar Collector With Image-Forming Mirror Cavity to Irradiate Small Central Volume

A unique solar thermal chamber has been designed and fabricated to produce the maximum concentration of solar energy and higher temperature possible. Its primary purpose was for solar plasma propulsion experiments and related material specimen testing above 3000 K. The design not only maximized solar concentration, but also, minimized infrared heat loss. This paper provides the underlying theory and operation of the chamber and initial optical correlation to the actual fabricated hardware. The chamber is placed at the focal point of an existing primary concentrator with a 2.74 m (9 ft) focal length. A quartz lens focuses a small sun image at the inlet hole of the mirrored cavity. The lens focuses two image planes at prescribed positions; the sun at the cavity's entrance hole and the primary concentrator at the junction plane of two surfaces that form the cavity chamber. The back half is an ellipsoid reflector that produces a 1.27 cm diameter final sun image. The image is "suspended in space," 7.1 cm away from the nearest cavity surface, to minimize thermal and contaminate damage to the mirror surfaces. A hemisphere mirror makes up the front chamber and has its center of curvature at the target image, where rays leaving the target are reflected back upon themselves, minimizing radiation losses.

Buchele, Don↗
NASA NTRS2010

Reducing Seal Adhesion in Low Impact Docking Systems

Silicone elastomers, used in seals for airlocks or other sealing surfaces in space, are sticky in their as-received condition. Because of the sticking, a greater force may be needed to separate the mating surfaces. If the adhesion is sufficiently high, a sudden unpredicted movement of the spacecraft during undocking, vibration, or uneven release could pull off the seal, resulting in a damage that would have to be repaired before another docking. The damaged seal can result in significant gas leakage and possibly in a catastrophic mishap impacting the safety of the crew. It is also possible that a compromised seal could result in a delayed but sudden gas leak that could put the crew at unexpected risk. This is especially of concern for androgynous seals, which have identical mating surfaces on both sides for interchangeability and redundancy. Such seals typically have elastomer-on-elastomer sealing surfaces. To reduce sticking, one could use release agents such as powders and lubricants, but these can be easily removed and transferred to other surfaces, causing uneven sealing and contamination. Modification of the elastomer surface to make a more slippery and less sticky surface that is integral with the bulk elastomer would be more desirable.

Banks, Bruce A.↗