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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
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Process for fabrication of enhanced β″-alumina solid electrolytes for energy storage devices and energy applications

A dense β″-alumina/zirconia composite solid electrolyte and process for fabrication are disclosed. The process allows fabrication at temperatures at or below 1600° C. The solid electrolytes include a dense composite matrix of β″-alumina and zirconia, and one or more transition metal oxides that aid the conversion and densification of precursor salts during sintering. The composite solid electrolytes find application in sodium energy storage devices and power-grid systems and devices for energy applications.

Lu, Xiaochuan↗
DOE OSTI2022

Low-cost, high-strength, cast creep-resistant alumina-forming alloys for heat-exchangers, supercritical CO2 systems and industrial applications

An austenitic Ni-base alloy includes, in weight percent: 2.5 to 4.75 Al; 13 to 21 Cr; 20 to 40 Fe; 2 to 5 total of at least one element selected from the group consisting of Nb and Ta; 0.25 to 4.5 Ti; 0.09 to 1.5 Si; 0 to 0.5 V; 0 to 2 Mn; 0 to 3 Cu; 0 to 2 of Mo and W; 0 to 1 of Zr and Hf; 0 to 0.15 Y; 0.01 to 0.45 C; 0.005 to 0.1 B; 0 to 0.05 P; less than 0.06 N; and balance Ni (38 to 46 Ni). The weight percent Ni is greater than the weight percent Fe. An external continuous scale comprises alumina. A stable phase FCC austenitic matrix microstructure is essentially delta-ferrite-free, and contains one or more carbides and coherent precipitates of γ′ and exhibits creep rupture life of at least 100 h at 900° C. and 50 MPa.

Muralidharan, Govindarajan↗
DOE OSTI2024

Hydrothermally and thermally stable catalytic materials based on theta-alumina

A material and a method of making hydrothermally stable (catalytic) materials on the basis of theta-alumina support that is thermally and hydrothermally stable up to 1,150 C with metal, mixed metal-, metal-oxide nanoparticles dispersed upon it. Such materials did not lose significant amounts of their catalytic activity at temperature ranges for industrially relevant applications (including hydrocarbon oxidation, nitric oxide reduction, carbon monoxide oxidation) even after hydrothermal aging up to 1,150° C.

Khivantsev, Konstantin↗
DOE OSTI2024

Microwave-assisted pyrolysis of hydrocarbons using iron-based alumina catalysts obtained via solution combustion synthesis

The demand for hydrogen is growing which makes the development of clean and efficient H2 synthesis technologies imperative. Microwave-assisted, thermocatalytic, dehydrogenation of hydrocarbons has demonstrated the ability to generate H2 with high yield and selectivity, leaving behind valuable solid carbon byproducts. However, this microwave-assisted process is unoptimized which prevents it from being utilized in industry. A critical component of optimization is the development of a catalyst that is catalytically active, a good microwave absorber, and can be regenerated for repeated dehydrogenation cycles. Previous studies that focused on plastic waste decomposition have used iron-based alumina (FeAlxOy) made via solution combustion synthesis (SCS). Unexplored is the effect of tuning SCS parameters on dehydrogenation performance, the use of these materials in hydrocarbon decomposition to H2, and the regeneration of these catalysts. This dissertation has three objectives: (1) characterize the relationship between SCS parameters and the material properties of FeAlxOy, (2) determine how differences in the material properties of FeAlxOy influence their performance as catalysts during microwave-assisted pyrolysis of fossil fuels, and (3) investigate the Boudouard reaction to regenerate the FeAlxOy post-dehydrogenation.

Chanoi, Zachary Aidan↗
DOE OSTI2021

Dual-shell silicate and alumina coating for long lasting and high capacity lithium ion batteries

In this work we demonstrate a theory-driven, novel dual-shell coating system of Li 2 SrSiO 4 and Al 2 O 3 , achieved via a facile and scalable sol-gel technique on LiCoO 2 electrode particles. The optimal thickness of each coating can lead to increased specific capacity (~185 mAh/g at 0.5 C-rate) at a cut-off potential of 4.5 V, and greater cycling stability at very high C rates (up to 10 C) in half-cells with lithium metal. The mechanism of this superior performance was investigated using a combination of X-ray and electron characterization methods. It shows that the results of this investigation can inform future studies to identify still better dual-shell coating schemes, achieved by such industrially feasible techniques, for application on similar, nickel-rich cathode materials.

25 ENERGY STORAGE↗
DOE OSTI2024

Apparent fracture toughness estimation of additively manufactured alumina from as-printed chevron-notched test specimens

Ceramic vat photopolymerization (VPP) is a digital light processing method used to make additively manufactured green ceramic components that are then sintered. Despite the ever-advancing maturation of this method's green-state process, some of the material properties of sintered VPP-processed ceramics are still not well defined or understood. One example is Mode I fracture toughness, K Ic . In this study, attention was devoted to K Ic measurement using net-shape chevron-notched bend bars that were VPP-processed and the examination of whether valid K Ic measurement could occur by testing them. Further, stable crack propagation was observed in >60% of tested samples, indicated by a smooth nonlinear transition through the measured maximum force prior to final fracture. However, their results cannot yet be responsibly referred to as K Ic because of continuing violations of other prerequisites needed for valid K Ic testing.

36 MATERIALS SCIENCE↗
NASA NTRSDate not supplied

A 96% Alumina based Packaging System for 500°C Test of SiC Integrated Circuits

With the development of silicon carbide (SiC) sensors and electronic devices for operation at 500°C, compatible packaging technologies are needed for long term high temperature test and deployment of these sensors and electronic devices. 96% Al2O3ceramic is an excellent electrically insulating material with acceptable dielectric constant and low dielectric loss over wide temperature and frequency ranges. This paper presents a packaging system for low power integrated circuits including a prototype 8-I/O chip-level package and printed circuit board (PCB) based on 96% Al2O3ceramic substrates and Au thick-film metallization for 500°C applications. The details related to designs of packages and PCBs, packaging materials, and specific packaging step recipes including wire -bonding and die-attach, are presented. Some test results of this prototype packaging approach applied to SiC integrated circuits at 500°C are reviewed.

High Temperature, Packaging, Alumina, Thick Film↗
DOE OSTI2026

Enabling Long Term, Shelf‐Stable Perovskite Solar Cells: Alumina Barriers to Protect Perovskite Devices from Moisture and Oxygen

Current encapsulation architectures for thin-film metal halide perovskite do not adequately eliminate all ambient stressors. Here, we develop low transmission rate barrier layers using atomic layer deposited (ALD) aluminum oxide grown directly on the completed photovoltaic (PV) device stack to provide an additional seal, prior to full packaging. We investigate the effect of deposition temperature and oxidant chemistries on the barrier growth for protection of perovskite photovoltaic devices. We characterize the layers individually, then integrate into devices to detail the tradeoff between protection and deposition compatibility. To enhance compatibility and impermeability, we present an approach using water as the aluminum oxidant during nucleation and switching from water to ozone for the remainder of the growth. At 50 nm, the barrier results in a water vapor transmission rate (WVTR) of 4.5·10 −4 g/m 2 /day, and 1,000-hour device stability under 45°C with 85% relative humidity without further packaging. This barrier provides sufficient protection to enable minimal degradation of the perovskite solar cells while completely submerged in water for 140 minutes. Additionally, we characterize the oxygen transmission rate (OTR) to be 0.49 cm 3 /m 2 /day at 23°C and 0% relative humidity, which is 1.5 orders of magnitude improvement over the OTR of the current encapsulation.

14 SOLAR ENERGY↗