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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Oxide mixture and complex oxide coatings for cathode materials

Cathode active materials are provided. The cathode active material can include a plurality of cathode active compound particles. A coating is disposed over each of the cathode active compound particles. The coating can include at least one of ZrO 2 , La 2 O 3 , a mixture of Al 2 O 3 and ZrO 2 or a mixture of Al 2 O 3 and La 2 O 3 . The battery cells that include the cathode active material are also provided.

Wang, Dapeng↗
DOE OSTI2022

Performance of stainless steel interconnects with (Mn,Co) 3 O 4 -Based coating for solid oxide electrolysis

Mixed transition-metal oxide coatings are commonly applied to stainless steel interconnects for solid oxide cell stacks. Such coatings reduce oxidation and Cr evaporation rates, leading to improved degradation rate and stack lifetime. Here, the ChromLok™ MCO-based composition (Mn,Co) 3 O 4 is applied to Crofer 22 APU stainless steel and evaluated specifically for application in solid oxide electrolyzer stacks operating around 800 °C and utilizing oxygen-ion-conducting solid oxide cells. The MCO coating is found to decrease the stainless steel oxidation rate by about one order of magnitude, and decrease the Cr evaporation rate by fourfold. Furthermore, the coating also dramatically lowers the rate of area-specific resistance increase for stainless steel coupons oxidized for 500 h with constant current applied, from 33 mΩ*cm 2 kh -1 for an uncoated coupon to less than 4 mΩ*cm2 kh -1 for coated coupons. The coating is demonstrated on full-scale interconnects for single-cells, where the coating dramatically reduces degradation rate, and for a stack, which displays stable operation for 700 h.

08 HYDROGEN↗
NASA NTRS2007

Thermal Properties of Oxides With Magnetoplumbite Structure for Advanced Thermal Barrier Coatings

Oxides having magnetoplumbite structure are promising candidate materials for applications as high temperature thermal barrier coatings because of their high thermal stability, high thermal expansion, and low thermal conductivity. In this study, powders of LaMgAl11O19, GdMgAl11O19, SmMgAl11O19, and Gd0.7Yb0.3MgAl11O19 magnetoplumbite oxides were synthesized by citric acid sol-gel method and hot pressed into disk specimens. The thermal expansion coefficients (CTE) of these oxide materials were measured from room temperature to 1500 C. The average CTE value was found to be approx.9.6x10(exp -6)/C. Thermal conductivity of these magnetoplumbite-based oxide materials was also evaluated using steady-state laser heat flux test method. The effects of doping on thermal properties were also examined. Thermal conductivity of the doped Gd0.7Yb0.3MgAl11O19 composition was found to be lower than that of the undoped GdMgAl11O19. In contrast, thermal expansion coefficient was found to be independent of the oxide composition and appears to be controlled by the magnetoplumbite crystal structure. Thermal conductivity testing of LaMgAl11O19 and LaMnAl11O19 magnetoplumbite oxide coatings plasma sprayed on NiCrAlY/Rene N5 superalloy substrates indicated resistance of these coatings to sintering even at temperatures as high as 1600 C.

Bansal, Narottam P.↗
NASA NTRS1985

Thermal barrier coating life prediction model

This is the first report of the first phase of a 3-year program. Its objectives are to determine the predominant modes of degradation of a plasma sprayed thermal barrier coating system, then to develop and verify life prediction models accounting for these degradation modes. The first task (Task I) is to determine the major failure mechanisms. Presently, bond coat oxidation and bond coat creep are being evaluated as potential TBC failure mechanisms. The baseline TBC system consists of an air plasma sprayed ZrO2-Y2O3 top coat, a low pressure plasma sprayed NiCrAlY bond coat, and a Rene'80 substrate. Pre-exposures in air and argon combined with thermal cycle tests in air and argon are being utilized to evaluate bond coat oxidation as a failure mechanism. Unexpectedly, the specimens pre-exposed in argon failed before the specimens pre-exposed in air in subsequent thermal cycles testing in air. Four bond coats with different creep strengths are being utilized to evaluate the effect of bond coat creep on TBC degradation. These bond coats received an aluminide overcoat prior to application of the top coat to reduce the differences in bond coat oxidation behavior. Thermal cycle testing has been initiated. Methods have been selected for measuring tensile strength, Poisson's ratio, dynamic modulus and coefficient of thermal expansion both of the bond coat and top coat layers.

Hillery, R. V.↗
NASA NTRS1980

Preliminary study of a solar selective coating system using black cobalt oxide for high temperature solar collectors

Black cobalt oxide coatings were deposited on thin layers of silver or gold which had been deposited on oxidized stainless steel substrates. The reflectance properties of these coatings were measured at various thicknesses of cobalt oxide for integrated values of the solar and infrared spectrum. The values of absorptance and emittance were calculated from the measured reflectance values before and after exposure in air at 650 C for 1000 hours. Also, these cobalt oxide/noble metal/oxide diffusion barrier coatings have absorptances greater than 0.90 and emittances of approximately 0.20 even after about 1000 hours at 650 C.

Mcdonald, G.↗
NASA NTRSDate not supplied

Measuring the Wear and Abrasive Resistance of Air Plasma Sprayed Aluminum Oxide for Lunar Exploration

Lunar regolith, especially finer dust particles traveling at high velocities, can cause significant wear and abrasive damage to structural components that ensure a prolongated presence on the surface of the Moon. With the absence of an atmosphere and lower gravity than on Earth, regolith particles maintain high velocities at large distances from where they were generated, for example next to lunar landers. Wear-resistant ceramic and ceramic composite materials can improve the durability of spacecraft components during long missions on the Moon’s surface. Aluminum oxide coatings are lightweight, have multifunctional properties, and have high strength including high hardness and wear resistance. These properties can help improve the durability of structures used in space exploration. Air plasma sprayed (APS) aluminum oxide coatings have demonstrated the potential to protect critical structures. This study investigated the abrasive wear resistance of APS aluminum oxide coatings via Taber abrasion experiments. Taber abrasion offers the advantage of quantifying the abrasive wear behavior of particles with different shapes on a surface. In this work, an abrasive wheel made of silicon carbide was utilized to evaluate wear properties of specimens progressively over 5000 cycles. This experiment focused on testing two series of specimens to determine whether a bond coat composed of nickel, chromium, aluminum, and yttrium (NiCrAlY) improved the protective behavior of the APS aluminum oxide coating. The specimens varied in topcoat thickness and were made with and without an approximately 100 µm bond coat layer. The mass of the specimens was measured at 400 cycles, 800 cycles, 3800 cycles, and 5000 cycles. Increasing thickness was found to result in higher wear for samples with and without a bond coat. Increased mass loss in samples with a bond coat was observed indicating a need for further studies on the overall impact of the use of a bond coat on the protective behavior of the coatings. To continue designing wear resistant coatings for structural protection in space missions, the multifunctional properties of the APS aluminum oxide coating will be studied. Future experiments will determine whether the APS aluminum oxide coating can protect the structures from other aspects of the harsh space environment, such as extreme temperature variations and ionizing radiation.

aluminum oxide↗
NASA NTRS1980

Preliminary study of a solar selective coating system using black cobalt oxide for high temperature solar collectors

Black cobalt oxide coatings (high solar absorptance layer) were deposited on thin layers of silver or gold (low emittance layer) which had been previously deposited on oxidized (diffusion barrier layer) stainless steel substrates. The reflectance properties of these coatings were measured at various thicknesses of cobalt for integrated values of the solar and infrared spectrum. The values of absorptance and emittance were calculated from the measured reflectance values, before and after exposure in air at 650 C for approximately 1000 hours. Absorptance and emittance were interdependent functions of the weight of cobalt oxide. Also, these cobalt oxide/noble metal/oxide diffusion barrier coatings have absorptances greater than 0.90 and emittances of approximately 0.20 even after about 1000 hours at 650 C.

Mcdonald, G.↗
DOE OSTI2024

The Effect of Sulfuric Acid Anodization on the Electrochemical Properties of Aluminum Alloy AlSi 10 Mg Prepared by Selective Laser Melting

Aluminum alloy, AlSi 10 Mg, prepared by selective laser melt (SLM) fabrication was anodized in 9.8% sulfuric acid (Type II) at 15 V for a total of 23 min. Experiments were performed to study the potentiostatic anodization process and its effects on the oxide coating morphology, thickness, and electrochemical properties of the alloy. Prior to anodization, the alloy microstructure is composed of aluminum cells encapsulated in a silicon network. Anodizing the abraded and polished AlSi 10 Mg surface produced a porous oxide layer with a thickness of 5μm. The oxide coating weight was 698 ± 29 mg/ft 2 . The oxide coating forms in the aluminum cells that are isolated from one another by the silicon eutectic phase. In electrochemical tests, the anodic and cathodic potentiodynamic polarization currents were suppressed by factors of 15× and 215×, respectively, as compared to the unanodized controls. The data indicate the anodic oxide coating suppresses the cathodic more than the anodic reaction rate. Linear polarization resistance (R p ) values increased by 279× after anodization. The corrosion current density values (j corr ) decreased by 133× after anodization. Taken together, the electrochemical data indicate the anodic oxide coating (unsealed) increases the corrosion resistance of the SLM alloy by two orders of magnitude.

Electrochemistry↗
NASA NTRS1961

Investigation of Oxidation-Resistant Coatings on Graphite and Molybdenum in Two Arc-Powered Facilities

A number of leading-edge specimens of ATJ graphite and 0.5-percent titanium-molybdenum alloy were tested in a 6-inch subsonic low-pressure arc-powered tunnel and a 1,500-kw subsonic arc jet to determine the effectiveness of several refractory coatings in preventing the oxidation of these materials. The results indicate that the siliconized coating for the ATJ graphite and the W-2 and Durak MG coatings for the titanium-molybdenum alloy provide adequate protection at temperatures up to 3,000 F for the durations of the tests in these facilities, approximately 70 seconds in the arc tunnel and approximately 10 minutes in the arc jet. Weight losses (less than one-half of 1 percent) experienced by a few of the coated specimens indicate that tests of longer duration in these environments may prove deleterious and that the stability of these coatings may be depreciated under the low-pressure environmental conditions encountered during reentry.

Peters, Roger W.↗
DOE OSTI2020

Graphene-coated metal oxide spinel cathodes

Disclosed herein are graphene-coated lithium manganese oxide spinels cathodes for high-performance batteries Li-ion batteries and methods for making thereof. A single-layer graphene coating is shown to significantly reduce manganese loss in the cathodes while concurrently promoting the formation of a well-defined solid electrolyte interphase layer.

25 ENERGY STORAGE↗