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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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All sourcesNASA NTRSDOE OSTI
NASA NTRS2009

Refractory Materials for Flame Deflector Protection System Corrosion Control: Refractory Ceramics Literature Survey

Ceramics can be defmed as a material consisting of hard brittle properties produced from inorganic and nonmetallic minerals made by firing at high temperatures. These materials are compounds between metallic and nonmetallic elements and are either totally ionic, or predominately ionic but having some covalent character. This definition allows for a large range of materials, not all applicable to refractory applications. As this report is focused on potential ceramic materials for high temperature, aggressive exposure applications, the ceramics reviewed as part of this report will focus on refractory ceramics specifically designed and used for these applications. Ceramic materials consist of a wide variety of products. Callister (2000) 1 characterized ceramic materials into six classifications: glasses, clay products, refractories, cements, abrasives, and advanced ceramics. Figure 1 shows this classification system. This review will focus mainly on refractory ceramics and cements as in general, the other classifications are neither applicable nor economical for use in large structures such as the flame trench. Although much work has been done in advanced ceramics over the past decade or so, these materials are likely cost prohibitive and would have to be fabricated off-site, transported to the NASA facilities, and installed, which make these even less feasible. Although the authors reviewed the literature on advanced ceramic refractories 2 center dot 3 center dot 4 center dot 5 center dot 6 center dot 7 center dot 8 center dot 9 center dot 10 center dot 11 center dot 12 after the review it was concluded that these materials should not be ' the focus of this report. A review is in progress on materials and systems for prefabricated refractory ceramic panels, but this review is focusing more on typical refractory materials for prefabricated systems, which could make the system more economically feasible. Refractory ceramics are used for a wide variety of applications. Figure 2 shows many ofthese applications, their life expectancy or requirement, and the exposure temperature for the refractory ceramic. Note that the exposure temperatures for refractory ceramics are very similar to the exposure conditions for specialty ceramics (rocket nozzles, space vehicle re-entry fields, etc.) and yet the life expectancy or requirement is relatively low. Currently NASA is repairing the refractory lining in the flame trench after every launch - although this is not a direct indication of low life expectancy, it does indicate that the current system may not be sufficiently durable to maximize economy. Better performing refractory ceramics are needed to improve the performance, economy, and safety during and after launches at the flame trenches at Kennedy Space Center (KSC). To achieve this goal a current study is underway to assess different refractory systems for possible use in the flame trenches at KSC. This report will target the potential applicability of refractory ceramics for use in the flame trenches. An overview of the different refractory ceramics will be provided (see Figure I). This will be followed with a brief description of the structure of refractory products, the properties and characteristics of different systems, the methodology for selecting refractories, and then a general design methodology. Based on these sections, future challenges and opportunities will be identified with the objective of improving the durability, performance, economy, and safety of the launch complex. Refractory ceramics are used for a wide variety of applications. Figure 2 shows many ofthese applications, their life expectancy or requirement, and the exposure temperature for the refractory ceramic. Note that the exposure temperatures for refractory ceramics are very similar to the exposure conditions for specialty ceramics (rocket nozzles, space vehicle re-entry fields, etc.) and yet the life expectancy or requirement is relatively low. Currently NASA is repairing the refractory lining in the flame trench after every launch - although this is not a direct indication of low life expectancy, it does indicate that the current system may not be sufficiently durable to maximize economy. Better performing refractory ceramics are needed to improve the performance, economy, and safety during and after launches at the flame trenches at Kennedy Space Center (KSC). To achieve this goal a current study is underway to assess different refractory systems for possible use in the flame trenches at KSC. This report will target the potential applicability of refractory ceramics for use in the flame trenches. An overview of the different refractory ceramics will be provided (see Figure I). This will be followed with a brief description of the structure of refractory products, the properties and characteristics of different systems, the methodology for selecting refractories, and then a general design methodology. Based on these sections, future challenges and opportunities will be identified with the objective of improving the durability, performance, economy, and safety of the launch complex.

Calle, Luz Marina↗
DOE OSTI2024

Development of Refractory Alloys and Refractory Coatings for Advanced Nuclear Reactors

The next generation of nuclear reactors will benefit from materials that enable operation at higher temperatures (>500°C), higher irradiation doses (up to 200 displacements per atom (dpa)), and the use of more corrosive and reactive coolants. This work package represents the first experimental steps towards a longer-term effort to develop refractory materials for nuclear energy applications which will enable operation under these conditions. Specifically, this work package focuses on additive manufacturing of refractories as both a refractory liner coating deposited onto the interior surface of a metallic tubular backbone and as bulk refractory alloys. During fiscal year 23 (FY23), several refractory metal coating systems and bulk alloys were examined and selected using a decision criteria matrix. The refractory metal coating systems included molybdenum, tungsten, and zirconium as refractory coatings on backbones of either carbon-carbon (C/C) or silicon carbide-silicon carbide (SiC/SiC) ceramic matrix composites. The bulk refractory alloys included C-103, WTa, and WNiFe as bulk alloys. During FY24 additional bulk refractory alloys and metallic backbones were evaluated using the decision criteria matrix based on input from the AMMT leadership team. These included 316 SS and 316H SS for the metallic backbones and Mo-La, Ta, and Nb1Zr as bulk refractory alloys. The primary focus for the FY24 effort was placed on establishing the capabilities to deposit refractory coatings based on the results of the scoring in the decision criteria matrix and finalizing the additively manufactured TZM studies which were incorporated into the AMMT program from the microreactor program. Further efforts were dedicated to establishing the capabilities to additively manufacture down-selected bulk refractory alloys.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2025

The Path towards Plasma Facing Components: A Review of State-of-the-art in W-Based Refractory High-Entropy Alloys

Developing advanced materials for plasma-facing components (PFCs) in fusion reactors is a crucial aspect for achieving sustained energy production. Tungsten (W) - based refractory high-entropy alloys (RHEAs) have emerged as promising candidates due to their superior radiation tolerance and high-temperature strength. This review paper will focus on recent advancements in W-based RHEA research, particularly emphasizing the key role of modelling using machine learning (ML) in the stage of discovery by predicting properties for each composition and expediting the identification of optimal RHEA compositions with desired properties. Additionally, the application of additive manufacturing (AM) techniques for fabricating W-based RHEAs is explored, highlighting their advantages for rapid prototyping and multi-compositional sample production in a high throughput manner. The review critically evaluates the current understanding of mechanical properties relevant to PFC applications, including high-temperature strength and ductility. Furthermore, the radiation tolerance of W-based RHEAs under irradiated conditions is discussed. Finally, the validity of current AM-manufactured W-based RHEAs as PFC materials is assessed, and key challenges and opportunities for future research are identified. This review aims to provide a comprehensive overview of W-based RHEAs for fusion applications and their potential to guide the development and validation of advanced refractory high entropy alloys.

Hatler, Caleb [University of Wisconsin-Madison]↗
NASA NTRS1983

Refractory precursor components of Semarkona chondrules and the fractionation of refractory elements among chondrites

Instrumental neutron activation analysis has been used to measure about 20 of the lithophile elements in 30 chondrules from the Semarkona chondrite. The amounts of oxidized iron were calculated from other compositional parameters, and Si concentrations are estimated from mass-balance considerations. It is suggested that the refractory component probably forms from fine grained materials that were able to equilibrate down to lower nebular temperatures. The chondrite matrix may have had an origin similar to that of the nonrefractory material. The low abundance of refractories and Mg in ordinary and enstatite chondrites was produced by the loss of materials having a higher refractory element/Mg ratio than that of the refractory element of the chondrules.

Grossman, J. N.↗
NASA NTRS1984

The geochemical behavior of refractory noble metals and lithophile trace elements in refractory inclusions in carbonaceous chondrites

Recent models of Ca, Al-rich (CAI) inclusion petrogenesis, and the recent availability of thermodynamic data have led to the reexamination of the geochemical behavior of the refractory noble metals (RNM) and several lithophile refractory trace elements in CAI's in the context of distillation models. Here, pertinent chemical and mineralogical properties of the various classes of refractory inclusions are reviewed, and calculations of the stability of LRTE-RNM alloys and several LRTE oxides under nebular conditions are presented. The calculations, observations and experimental results are applied to a new model of the origin of refractory metal nuggets, and a specific mechanism is identified for producing Group II chemical patterns in a cold star nebula by fractionating interstellar dust at low temperature on the basis of physical differences between different populations of pre-solar grains.

Fegley, B., Jr.↗
DOE OSTI2021

Computational exploration of biomedical HfNbTaTiZr and Hf 0.5 Nb 0.5 Ta 0.5 Ti 1.5 Zr refractory high-entropy alloys

Refractory high entropy alloys (RHEAs) have been proven to be a potential candidate in the biomedical field due to their balanced mechanical properties and biocompatible composition. Recent experimental findings show that RHEAs like HfNbTaTiZr and Hf 0.5 Nb 0.5 Ta 0.5 Ti 1.5 Zr have good mechanical properties such as high polarization and wear resistance than others which establish them as potential materials for biomedical application. In this work, we performed first-principles density functional theory calculations on the mechanical and thermal properties of HfNbTaTiZr and Hf 0.5 Nb 0.5 Ta 0.5 Ti 1.5 Zr. The predicted lattice constant, density, Young's modulus, and Vickers hardness are consistent with the available experimental report, which verifies the accuracy of the applied model. The thermal coefficient of linear expansion of both RHEAs has been investigated by utilizing the Debye theory. The present methods could be applied to study other future RHEAs on exploration of their physical properties.

36 MATERIALS SCIENCE↗
NASA NTRS1980

Refractory metal particles in refractory inclusions in the Allende meteorite

SEM and X-ray analysis were used to study refractory metal particles in five calcium-aluminum-rich inclusions in the Allende meteorite, and a complex variety of compositions and large departures from equilibrium were found. It is suggested that these particles could have been primordial condensates which were isolated from the nebula and from each other at different times by cocondensing oxides. Selective diffusion and/or oxidation of the more oxidizable metals (Mo, W, Fe, and Ni), phase segregations into different alloy phases (fcc, bcc, hcp, and, possibly, ordered phases), and the formation of metastable condensates could have been involved in the genesis of these materials

Fuchs, L. H.↗
NASA NTRS1993

Refractory inclusions from the Leoville, Efremovka, and Vigarano C3V chondrites - Major element differences between Types A and B, and extraordinary refractory siderophile element compositions

Instrumental neutron activation analysis is used to measure the bulk chemical compositions of ten Ca-, Al-rich inclusions (CAIs) from three C3V chondrites of the reduced subgroup, five from Leoville, three from Efremovka, and two from Vigarano. Six of the inclusions are found to possess very large fractionations between refractory siderophile elements, and four of the six have remarkably high concentrations of these siderophiles, as compared with CAIs analyzed previously. Most of the inclusions analyzed here have lower concentrations of Na, Au, Fe, Zn, and Mn than their Allende counterparts, consistent with the idea that they have experienced secondary alteration at a higher temperature or for a shorter time than did Allende inclusions.

Sylvester, Paul J.↗
NASA NTRS2017

Fine-Gained CAIs in Comet Samples: Moderate Refractory Character and Comparison to Small Refractory Inclusions in Chondrites

Examination of >200 comet Wild 2 particles collected by the Stardust (SD) mission shows that the CAI abundance of comet Wild 2's rocky material is near 1% and that nearly 50% of all bulbous tracks will contain at least one recognizable CAI fragment. A similar abundance to Wild 2 is found in a giant cluster IDP thought to be of cometary origin. The properties of these CAIs and their comparison with meteoritic CAIs provide important clues on the role of CAIs in the early Solar System (SS) and how they were transported to the edge of the solar nebula where Kuiper Belt comets formed. Previously, only two CAIs in comet Wild 2 had been identified and studied in detail. Here we present 2 new Wild 2 CAIs and 2 from a giant cluster cometary IDP, describe their mineralogical characteristics and show that they are most analogous to nodules in spinel-rich, fine-grained inclusions (FGIs) observed in CV3 and other chondrites. Additionally, we present new O isotope measurements from one CAI from comet Wild 2 and show that its oxygen isotopic composition is similar to some FGIs. This is only the second CAI from Wild 2 in which O isotopes have been measured.

Joswiak, D. J.↗