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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 289 records · Page 16

MAB Phase Ceramics for Lunar Applications

During the ten-week internship my work focused on designing characterization protocol for 3D printed MAB phase ceramics on steel and Tiplates. I was mentored by Dr. Samuel Hocker of NASA and advised by Dr. Gupta from University of North Dakota. I also collaborated with Mackenzie Short from the University of North Dakota. The characterization protocol was divided into following steps; initially, we performed visual inspection of the plates. During this process, the coatings which spalled or delaminated were discarded for further evaluation. During the next step, we performed optical microscopy to discern and document surface features and porosities of the samples. We also noted some decomposition under the optical microscope as well. Thereafter, profilometry analysis was performed to understand the effect of power density on the surface roughness. Due to the deposited powder over the samples, the profilometry was inconclusive. We then cleaned the samples on the steel plate using ethanol and cotton swabs to wipe up the loose powder covering the samples. Detailed SEM analysis was then performed on the cleaned specimens. In parallel, the 3D printed samples on the Tiplate were cleaned by using an ultrasonic bath for 1h. Optical imaging showed that this cleaning process was more effective for cleaning except that small cracks propagated through the layered ceramics. The profilometry data gathered on the titanium plate after cleaning was more conclusive. The SEM data on the steel plate showed that there is decomposition at all wattages although at 100 W the extent of decomposition was lower. We are planning to characterize the steel samples after cleaning in ultrasonic bath for 5-10 min to minimize cracking during the cleaning process. In addition, we are also planning to study the fractured surface by SEM analysis.

Additive Manufacturing, Laser Powder Bed Fusion, S↗

Bridging microscopic dynamics and rheology in the yielding of charged colloidal suspensions

The yielding of soft materials is critical to many natural and industrial processes, yet experimental insights into microscopic aspects of yielding are limited. This study combines angle X-ray scattering, X-ray photon correlation spectroscopy, and in situ rheology (Rheo-SAXS-XPCS) with fast lubrication dynamics simulations to examine how interparticle interactions influence yielding in charged colloidal suspensions. By tuning attraction through salt addition, we compare repulsive and attractive systems under deformation. Repulsive suspensions yield uniformly with Andrade-like creep and minimal structural change. In contrast, attractive suspensions show complex behaviors, including shear banding, delayed yielding, and resolidification, governed by transient dynamics at shear band interfaces. These results directly link microscopic particle dynamics to macroscopic flow and demonstrate how interaction potentials control rheological behavior. This work offers a framework for designing soft materials with tailored properties for applications in coatings, food processing, drug delivery, and other technologies requiring precise mechanical control.

Molecular Dynamics Simulation↗

Joint Test Report for Validation of Alternative Low-Emission Surface Preparation/Depainting Technologies for Structural Steel

Headquarters National Aeronautics and Space Administration (NASA) chartered the NASA Acquisition Pollution Prevention (AP2) Office to coordinate agency activities affecting pollution prevention issues identified during system and component acquisition and sustainment processes. The primary objectives of the AP2 Office are to: (1) Reduce or eliminate the use of hazardous materials or hazardous processes at manufacturing, remanufacturing, and sustainment locations. (2) Avoid duplication of effort in actions required to reduce or eliminate hazardous materials through joint center cooperation and technology sharing. The objective of this project was to qualify candidate alternative Low-Emission Surface Preparation/Depainting Technologies for Structural Steel applications at NASA facilities. This project compares the surface preparation/depainting performance of the proposed alternatives to existing surface preparation/depainting systems or standards. This Joint Test Report (JTR) contains the results of testing as per the outlines of the Joint Test Protocol (JTP), Joint Test Protocol for Validation of Alternative Low-Emission Surface Preparation/Depainting Technologies for Structural Steel, and the Field Test Plan (FTP), Field Evaluations Test Plan for Validation of Alternative Low-Emission Surface Preparation/Depainting Technologies for Structural Steel, for critical requirements and tests necessary to qualify alternatives for coating removal systems. These tests were derived from engineering, performance, and operational impact (supportability) requirements defined by a consensus of government and industry participants. This JTR documents the results of the testing as well as any test modifications made during the execution of the project. This JTR is made available as a reference for future pollution prevention endeavors by other NASA Centers, the Department of Defense and commercial users to minimize duplication of effort. The current coating removal processes identified herein are for polyurethane, epoxy and other paint systems applied by conventional wet-spray processes. A table summarizes the target hazardous materials, processes and materials, applications, affected programs, and candidate substrates.

Lewis, Pattie↗

Tackling issues of lithium metal anodes with a novel polymeric lithicone coating

Lithium metal (Li) has been hindered from as anodes in commercial batteries for over 50 years, due to two main issues: continuous formation of solid electrolyte interphase (SEI) and lithium dendritic growth. In this work, we report a new strategy to tackle these issues, i.e., using molecular layer deposition (MLD) to grow an ionically conducting but electrically insulating polymeric lithicone coating, an Li-containing triethanolamine (LiTEA). Our electrochemical tests revealed that this LiTEA coating could serve as an exceptional protection layer over Li anodes. Consequently, the LiTEA-coated Li electrodes could achieve a superior cyclability of > 10000 Li stripping/plating cycles at a current density of 5 mA cm -2 and a long cyclability of > 5500 cycles at 2 mA cm -2 in Li||Li symmetric cells without failures, under a fixed areal capacity of 1 mAh cm -2 . Characterizations using scanning electron microscopy and X-ray photoelectron microscopy verified that Li + ions could be easily extracted through and deposited under the LiTEA coating during the stripping/plating processes. Consequently, this LiTEA coating significantly inhibited the formation of SEI and Li dendrites. This underlies the long cycling lifetime of the LiTEA-coated Li||Li cells. Coupling with the nickel-rich LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811) cathodes, more encouragingly, the LiTEA-coated Li anodes could remarkably extend the cyclability and sustainable capacity of the resultant Li||NMC full cells. Finally, we also demonstrated that the performance of Li||NMC cells could be further improved through combining an LiTEA-coated Li anode with an Li 2 S-modified NMC811 via atomic layer deposition (ALD). Thus, this study is inspiring for developing high-energy Li||NMC lithium metal batteries.

25 ENERGY STORAGE↗

Recipe for coating ceramic blades for ion trapping

The first batches of ion traps patterned and coated were processed per the standard 3-step clean, air fire, and metallization processes. The third or fourth lot using this process resulted in poorly adhering metallization. Up until this point, the standard process was used to metallize and pattern ceramic ion traps without fail. At about the 4th batch of parts something changed. After the 5th batch, the ceramic ion traps received generally came with some unknown contamination that does not come off in a standard 3-step clean (Lenium Vapor Degreaser, Acetone, IPA) and air fire (860C for 1 hour) for which this process removes the vast majority of all contamination for most ceramic metallization. This is highly unusual. Using HF + Boiling H 2 O 2 is extreme for cleaning the ceramic ion traps. The contamination was never identified and is stubborn to effectively clean. Standard as-fired ceramic should be very easy to clean as if s fired at temperatures greater than 1400°C and not much in terms of contamination should exist at these temperatures, so there must be an intermediate step/process which is imparting this contamination. It is likely a polishing compound or previous polishing contaminant, but also not easily visually distinguishable until after metallization. The halo marks observed on parts might be fingerprints (less likely) or potential polishing marks (more likely) as metallization typically doesn't cover/hide any damage or contamination, but rather quite clearly the opposite, it accentuates it. Blotchy appearances in the metallization usually indicated an adhesion issue. As a result of the fragility of the parts (yield loss due to handling) and difficulty in identifying the contamination during cleaning, we have taken a conservative approach of HF + H 2 O 2 cleaning for all batches after the contamination and adhesion issues were identified.

36 MATERIALS SCIENCE↗

Improving Reliability, Weight and Cost of Gas-Fired Absorption Heat Pumps

The objective of the project was to identify and verify a viable path for the use of aluminum tubes in evaporators for gas-fired ammonia-water absorption heat pumps (GAHP), via identification of a suitable alloy, coating, inhibitor, process, or combination, for the purpose of achieving weight and cost reduction.

03 NATURAL GAS↗

Prediction of Performance Variation Caused by Manufacturing Tolerances and Defects in Gas Diffusion Electrodes of Phosphoric Acid (PA)–Doped Polybenzimidazole (PBI)-Based High-Temperature Proton Exchange Membrane Fuel Cells

The automated process of coating catalyst layers on gas diffusion electrodes (GDEs) for high-temperature proton exchange membrane fuel cells results inherently into a number of defects. These defects consist of agglomerates in which the platinum sites cannot be accessed by phosphoric acid and which are the consequence of an inconsistent coating, uncoated regions, scratches, knots, blemishes, folds, or attached fine particles—all ranging from μm to mm size. These electrochemically inactive spots cause a reduction of the effective catalyst area per unit volume (cm2/cm3) and determine a drop in fuel cell performance. A computational fluid dynamics (CFD) model is presented that predicts performance variation caused by manufacturing tolerances and defects of the GDE and which enables the creation of a six-sigma product specification for Advent phosphoric acid (PA)-doped polybenzimidazole (PBI)-based membrane electrode assemblies (MEAs). The model was used to predict the total volume of defects that would cause a 10% drop in performance. It was found that a 10% performance drop at the nominal operating regime would be caused by uniformly distributed defects totaling 39% of the catalyst layer volume (~0.5 defects/μm2). The study provides an upper bound for the estimation of the impact of the defect location on performance drop. It was found that the impact on the local current density is higher when the defect is located closer to the interface with the membrane. The local current density decays less than 2% in the presence of an isolated defect, regardless of its location along the active area of the catalyst layer.

Gurau, Vladimir (ORCID:0000000327429061)↗

Protective overcoating of films

Kodak Film Type SO-212 was emulsion overcoated with gelatin and lacquer to evaluate the feasibility of application of the coatings, any image degradation, and the relative protection offered against abrasion. Evaluated were: Eastman motion picture film lacquer Type 485, water solutions of Eastman purified Calfskin gelatin, and experimental Eastman gelatin stripping film of 4 and 6 microns. Conclusions reached were: (1) All coatings can be applied with relative ease with the only limitation being that of equipment. (2) None of the coatings degrade the processed image. (3) All of the coatings provide protection to the emulsion. These conclusions apply to any film which may be considered for overcoating.

Maas, K. A.↗

Evaluation of glass resin coatings for solar cell applications

Using a variety of non-vacuum deposition techniques coatings were implemented on silicon solar cells and arrays of cells interconnected on Kapton substrates. The coatings provide both antireflection optical matching and environmental protection. Reflectance minima near 2% was achieved at a single wavelength in the visible. Reflectance averaging below 5% across the useful collection range was demonstrated. The coatings and methods of deposition were: (1) Ta2O5 spun, dipped or sprayed; (2) Ta2O5.SiO2 spun, dipped or sprayed; (3) GR908 (SiO2) spun, dipped, or sprayed. Total coating thickness were in the range of 18 microns to 25 microns. The coatings and processes are compatible with single cells or cells mounted on Kapton substrates.

Field, M. B.↗

Development of sputtering process to deposit stoichiometric zirconia coatings for the inside wall of regeneratively cooled rocket thrust chambers

Thermal barrier coatings of yttria stabilized zirconia and zirconia-ceria mixtures were deposited by RF reactive sputtering. Coatings were 1-2 mils thick, and were deposited on copper cylinders intended to simulate the inner wall of a regeneratively cooled thrust chamber. Coating stoichiometry and adherence were investigated as functions of deposition parameters. Modest deposition rates (approximately 0.15 mil/hr) and subambient sustrate temperatures (-80 C) resulted in nearly stoichiometric coatings which remained adherent through thermal cycles between -196 and 400 C. Coatings deposited at higher rates or substrates temperatures exhibited greater oxygen deficiences, while coatings deposited at lower temperatures were not adherent. Substrate bias resulted in structural changes in the coating and high krypton contents; no clear effect on stoichiometry was observed.

Busch, R.↗

Improved adherence of T1C coatings to steel

Modified process for RF sputtering of titanium carbide coatings onto 440-C steel has resulted in improved adherence. Small partial pressure of nitrogen, approximately 0.5 percent, during first minutes of deposition markedby improved adherence, friction, and wear properties when compared with coatings applied on sputter-etched surfaces, or oxidized surfaces or in presence of small oxygen partial pressure. X-ray photoelectron spectroscopy and X-ray diffraction were used to characterize resultant coatings.

Brainard, W. A.↗

Processing modifications for improved propellants - Coated oxidizers

The present investigation is concerned with a technique which makes it possible to improve greatly the performance of composite propellants by alleviating the combustion instability problem. The technique involves the coating of the oxidizer crystals (typically ammonium perchlorate) with a suitably selected chemical. For each application the chemical for the coating is chosen on the basis of a screening procedure including the employment of differential scanning calorimetry and the use of a thermogravimetric analyzer. It is particularly important that the coat chemicals have good thermochemical stability at temperatures up to the normal surface temperature of the propellant during time-independent combustion (typically 800 to 900 K). At higher temperatures, sudden degradation should occur over a vary narrow temperature range (10-20 C).

Helmy, A. K.↗

Front surface passivation of silicon solar cells with antireflection coating

It is demonstrated that the deposition and postdeposition sintering of an antireflection (AR) coating in hydrogen acts to passivate silicon solar cells. Cells with and without an SiO2 passivating layer, coated with a TiO(x)/Al2O3 AR coating, showed comparable enhancements in short-wavelength spectral response and in open-circuit voltage Voc after sintering at 400 C for 5 min in a hydrogen ambient. The improvement in Voc of cells without SiO2 is attributed to front-surface passivation by the AR coating during processing.

Crotty, G.↗

Continuous Measurement Of Mass Density Of Yarn

Prototype instrument provides measurement data from which one computes mass density of strand of yarn. Includes fixtures placing known length of yarn under known tension across fixed and movable support. Transverse vibrations induced in yarn by moving movable support up and down. Source of light illuminates photodetector at midlength of yarn, and photodetector senses repeated shadowing caused by vibration of yarn through light, thereby measuring vibrations. Also used for continuous real-time monitoring of such yarn-manufacturing processes as coating or impregnation.

Hinkley, Jeffrey A.↗

Preparation Of Sources For Plasma Vapor Deposition

Multicomponent metal targets serving as sources of vapor for plasma vapor deposition made in modified pressureless-sintering process. By use of targets made in modified process, one coats components with materials previously plasma-sprayed or sintered but not plasma-vapor-deposited.

Waters, William J.↗