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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 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Laser gain media fabricated via direct ink writing (DIW) and ceramic processing

A transparent ceramic optic includes: a lasing region comprising at least one lasing species dopant; and a transparent region transparent to light generated by the lasing species. At least the transparent region is doped with at least one other dopant species such that the lasing region and the transparent region are characterized by a difference in refractive index between the two regions in an amount of about 1.0×10−4 or less. Inventive formulations of inks suitable for fabricating transparent ceramic optics having desirable compositional characteristics such as concentration gradients in desired spatial arrangements, e.g. using additive manufacturing techniques such as direct ink writing and/or extrusion freeform fabrication are also disclosed, along with suitable techniques for forming the transparent ceramic optics from such inks.

Payne, Stephen A.↗
DOE OSTI2019

Structural and Magnetic Properties of La-Substituted M-Type Hexagonal Sr–Ni Ferrites Synthesized by Ball-Milling-Assisted Ceramic Process

Sr{sub 0.5}Ni{sub 0.5}La{sub x}Fe{sub 12 − x}O{sub 19} (x = 0, 0.08, 0.16, and 0.24) hexaferrites have been synthesized by ball-milling-assisted ceramic process. The calcined samples are characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectra (FTIR), and vibrating sample magnetometry (VSM). XRD reveals that all samples consist of the main M-type hexagonal Sr ferrite phase and a low amount of rhombohedral Fe{sub 2}O{sub 3} as secondary phase, and a continuous increase of the hexagonal lattice parameters with substitution content (x). Magnetic characterization indicates that all Sr{sub 0.5}Ni{sub 0.5}La{sub x}Fe{sub 12 − x}O{sub 19} samples have a hard magnetic property. Substitution of Fe{sup 3+} ions by La{sup 3+} ions can obviously improve the specific saturation magnetization, remanence, magnetic moment, and effective anisotropy constant. Specific saturation magnetization, remanence, and the magnetic moment reach a maximum at x= 0.24 and calcination temperature of 1050 {sup ∘}C.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2022

Development of a Kollidon 90F-PEG300-Glycerin Binder for PZT 95/5 Ceramic Processing

This SAND Report documents the development of organic binder system for PZT 95/5 consisting of Kollidon 90F, PEG300, and glycerin. Binders are a critical component in the manufacture of ceramic components. Low performing binders can result in poor yield and lower performance of ceramic components. This study sought to develop a well performing binder system for PZT 95/5 ceramics to support Ferroelectric Neutron Generator manufacturing. The study explored the glass transition temperature, powder compaction properties, green strengths, and thermal decomposition over a wide composition range. An optimal composition was found consisting of 1.3 wt.% Kollidon 90F, 0.5 wt.% PEG300, and 0.2 wt.% glycerin, and incorporating humidity conditioning . The results showed that the optimized binder exhibited improved compaction performance and enhanced green strength compared to a baseline binder and at lower loading. Further, sintered PZT 95/5 parts prepared using the optimized binder exhibited ~5% improved polarization performance without alteration to the microstructure.

36 MATERIALS SCIENCE↗
DOE OSTI2014

SRNL CRP progress report [Development of Melt Processed Ceramics for Nuclear Waste Immobilization]

A multi-phase ceramic waste form is being developed at the Savannah River National Laboratory (SRNL) for treatment of secondary waste streams generated by reprocessing commercial spent nuclear. The envisioned waste stream contains a mixture of transition, alkali, alkaline earth, and lanthanide metals. Ceramic waste forms are tailored (engineered) to incorporate waste components as part of their crystal structure based on knowledge from naturally found minerals containing radioactive and non-radioactive species similar to the radionuclides of concern in wastes from fuel reprocessing. The ability to tailor ceramics to mimic naturally occurring crystals substantiates the long term stability of such crystals (ceramics) over geologic timescales of interest for nuclear waste immobilization [1]. A durable multiphase ceramic waste form tailored to incorporate all the waste components has the potential to broaden the available disposal options and thus minimize the storage and disposal costs associated with aqueous reprocessing.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2023

In situ probing of interfacial roughness and transient phases during ceramic cold sintering process

The ceramic cold sintering process (CSP) offers an eco-friendly approach to producing fully dense ceramics at low temperatures. However, an incomplete mechanistic understanding hinders its optimization and widespread adoption. In this study, we analyze the microstructural and structural changes in ZnO, a model CSP system, using in situ synchrotron-based high-energy small-angle X-ray scattering and X-ray diffraction techniques. Our results reveal the time evolution of ZnO particles' surface area and roughness, reflecting the dissolution and re precipitation processes that enable densification. The in situ measurements supply valuable kinetic data for these stages of CSP. Alongside microstructural changes and densification, we observed the evolution of secondary phases representing reaction products between ZnO and acetic acid, the solvent used. The initial ZnO/solvent mixture's dominant secondary phase is attributed to zinc acetate, which is gradually replaced by a zinc soap-type structure during CSP. This structure has a large (≈ 21 Å) lattice parameter and is assumed to have a layered nature. The formation of this soap phase, which is retained in the sintered product as an intergranular component, appears to be a signature of successful cold sintering as it facilitates mass transport, leading to densification. Here, our study underscores the potential of in situ synchrotron characterization for revealing microstructural and phase-evolution details during CSP. These findings, which would be challenging to obtain through ex situ measurements, provide crucial data to guide and validate theoretical models, ultimately enhancing CSP's effectiveness and adoption.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Crystalline Ceramic Waste Forms: Comparison Of Reference Process For Ceramic Waste Form Fabrication

The research conducted in this work package is aimed at taking advantage of the long term thermodynamic stability of crystalline ceramics to create more durable waste forms (as compared to high level waste glass) in order to reduce the reliance on engineered and natural barrier systems. Durable ceramic waste forms that incorporate a wide range of radionuclides have the potential to broaden the available disposal options and to lower the storage and disposal costs associated with advanced fuel cycles. Assemblages of several titanate phases have been successfully demonstrated to incorporate radioactive waste elements, and the multiphase nature of these materials allows them to accommodate variation in the waste composition. Recent work has shown that they can be produced from a melting and crystallization process. The objective of this report is to explore the phase formation and microstructural differences between lab scale melt processing in varying gas environments with alternative densification processes such as Hot Pressing (HP) and Spark Plasma Sintering (SPS). The waste stream used as the basis for the development and testing is a simulant derived from a combination of the projected Cs/Sr separated stream, the Trivalent Actinide - Lanthanide Separation by Phosphorous reagent Extraction from Aqueous Komplexes (TALSPEAK) waste stream consisting of lanthanide fission products, the transition metal fission product waste stream resulting from the transuranic extraction (TRUEX) process, and a high molybdenum concentration with relatively low noble metal concentrations. Melt processing as well as solid state sintering routes SPS and HP demonstrated the formation of the targeted phases; however differences in microstructure and elemental partitioning were observed. In SPS and HP samples, hollandite, pervoskite/pyrochlore, zirconolite, metallic alloy and TiO 2 and Al 2 O 3 were observed distributed in a network of fine grains with small residual pores. The titanate phases that incorporate M +3 rare earth elements were observed to be distinct phases (ex. Nd 2 Ti 2 O 7 with less degree of substitution as compared to the more homogeneous melt processed samples where a high degree of substitution and variation of composition within grains was observed. Liquid phase sintering was enhanced in reducing gas environments and resulted in large (10-200 microns) irregular shaped grains along with large voids associated with the melt process; SPS and HP samples exhibited finer grain size with smaller voids. Metallic alloys were observed in the bulk of the sample for SPS and HP samples, but were found at the bottom of the crucible in melt processed trials. These results indicate that for a first melter trial, the targeted phases can be formed in air by utilizing Ti/TiO 2 additives which aid phase formation and improve the electrical conductivity. Ultimately, a melter run in reducing gas environments would be beneficial to study differences in phase formation and elemental partitioning.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2015

Melt Processed Crystalline Ceramic Waste Forms for Advanced Nuclear Fuel Cycles: CRP T21027 1813: Processing technologies for high level waste, formulation of matrices and characterization of waste forms, Task 17208 (Final Report)

A multi-phase ceramic waste form is being developed at the Savannah River National Laboratory (SRNL) for treatment of secondary waste streams generated by reprocessing commercial spent nuclear. The envisioned waste stream contains a mixture of transition, alkali, alkaline earth, and lanthanide metals. Ceramic waste forms are tailored (engineered) to incorporate waste components as part of their crystal structure based on knowledge from naturally found minerals containing radioactive and non-radioactive species similar to the radionuclides of concern in wastes from fuel reprocessing. The ability to tailor ceramics to mimic naturally occurring crystals substantiates the long term stability of such crystals (ceramics) over geologic timescales of interest for nuclear waste immobilization [1]. A durable multi-phase ceramic waste form tailored to incorporate all the waste components has the potential to broaden the available disposal options and thus minimize the storage and disposal costs associated with aqueous reprocessing. This report summarizes results from three years of work on the IAEA Coordinated Research Project on “Processing technologies for high level waste, formulation of matrices and characterization of waste forms” (T21027), and specific task “Melt Processed Crystalline Ceramic Waste Forms for Advanced Nuclear Fuel Cycles” (17208).

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2015

Melt Processed Crystalline Ceramic Waste Forms for Advanced Nuclear Fuel Cycles CRP T21027 1813: Processing technologies for high level waste, formulation of matrices and characterization of waste forms, Task 17208 (Final Report)

A multi-phase ceramic waste form is being developed at the Savannah River National Laboratory (SRNL) for treatment of secondary waste streams generated by reprocessing commercial spent nuclear. The envisioned waste stream contains a mixture of transition, alkali, alkaline earth, and lanthanide metals. Ceramic waste forms are tailored (engineered) to incorporate waste components as part of their crystal structure based on knowledge from naturally found minerals containing radioactive and non-radioactive species similar to the radionuclides of concern in wastes from fuel reprocessing. The ability to tailor ceramics to mimic naturally occurring crystals substantiates the long term stability of such crystals (ceramics) over geologic timescales of interest for nuclear waste immobilization. A durable multi-phase ceramic waste form tailored to incorporate all the waste components has the potential to broaden the available disposal options and thus minimize the storage and disposal costs associated with aqueous reprocessing. This report summarizes results from three years of work on the IAEA Coordinated Research Project on “Processing technologies for high level waste, formulation of matrices and characterization of waste forms” (T21027), and specific task “Melt Processed Crystalline Ceramic Waste Forms for Advanced Nuclear Fuel Cycles” (17208).

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2014

A quantitative acoustic emission study on fracture processes in ceramics based on wavelet packet decomposition

We base a quantitative acoustic emission (AE) study on fracture processes in alumina ceramics on wavelet packet decomposition and AE source location. According to the frequency characteristics, as well as energy and ringdown counts of AE, the fracture process is divided into four stages: crack closure, nucleation, development, and critical failure. Each of the AE signals is decomposed by a 2-level wavelet package decomposition into four different (from-low-to-high) frequency bands (AA{sub 2}, AD{sub 2}, DA{sub 2}, and DD{sub 2}). The energy eigenvalues P{sub 0}, P{sub 1}, P{sub 2}, and P{sub 3} corresponding to these four frequency bands are calculated. By analyzing changes in P{sub 0} and P{sub 3} in the four stages, we determine the inverse relationship between AE frequency and the crack source size during ceramic fracture. AE signals with regard to crack nucleation can be expressed when P{sub 0} is less than 5 and P{sub 3} more than 60; whereas AE signals with regard to dangerous crack propagation can be expressed when more than 92% of P{sub 0} is greater than 4, and more than 95% of P{sub 3} is less than 45. Geiger location algorithm is used to locate AE sources and cracks in the sample. The results of this location algorithm are consistent with the positions of fractures in the sample when observed under a scanning electronic microscope; thus the locations of fractures located with Geiger's method can reflect the fracture process. The stage division by location results is in a good agreement with the division based on AE frequency characteristics. We find that both wavelet package decomposition and Geiger's AE source locations are suitable for the identification of the evolutionary process of cracks in alumina ceramics.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

Aerosol Deposition: Room Temperature Solid-State Deposition of Ceramics

The ability to integrate ceramics with other materials has been limited by the high temperature s (>800C) associated with ceramic processing. A novel process, known as aerosol deposition (AD), capable of preparing ceramic films at room temperature (RT) has been the subject of recent interest in the thermal spray and microelectronics communities. In this process, ceramic particles are accelerated using pressurized gas, impacted on a substrate and form a dense film under vacuum. This revolutionary process eliminates high temperature processing, enabling new coatings and microelectronic device integration as a back end of line process, in which ceramics can be deposited on metals, plastics, and glasses . Future impact s of this technology on Sandia's mission could include improved ceramic integration, miniaturized magnetic circulators in radar applications, new RF communication products, modification of commercial - off - the - shelf electronics, fabrication of conformal capacitors, thin batteries, glass - to - metal seals, and transparent electronics. Currently, optimization for RT solid - state deposition of ceramics is achieved empirically and fundamental mechanisms for ceramic particle - particle bonding are not well understood. Obtaining this knowledge will allow process - microstructure - property relation ship realization and will enable a differentiating ceramic integration capability. This LDRD leveraged Sandias existing equipment and capabilities in simulation, experimentation, and materials characterization to discover the fundamental mechanisms for ceramic particle deformation, particle - substrate bonding, and particle - particle bonding in RT consolidated films. RT deformation of individual Al 2 O 3 particles was examined computationally and experimentally as a model system for understanding the complex dynamics associated with in vacuo RT deposition conditions associated with AD. Subsequently, particle - substrate bonding and particle - particle bonding in AD Al 2 O 3 consolidated films were examined computationally and experimentally. Fundamental mechanisms behind the AD process were proposed.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Ceramic matrix composite component and process of producing a ceramic matrix composite component

A process of producing a ceramic matrix composite component. The process includes positioning core plies on a mandrel. At least partially rigidizing the core plies to form a preform ceramic matrix composite arrangement defining a tip cavity and a hollow region. Ceramic matrix composite tip plies are positioned on the preform ceramic matrix composite arrangement and within the tip cavity. The ceramic matrix composite tip plies are densified to form a tip region of the composite component.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Deformation behavior of sub-micron and micron sized alumina particles in compression

The ability to integrate ceramics with other materials has been limited due to high temperature (>800°C) ceramic processing. Recently, researchers demonstrated a novel process, aerosol deposition (AD), to fabricate ceramic films at room temperature (RT). In this process, sub-micron sized ceramic particles are accelerated by pressurized gas, impacted on the substrate, plastically deformed, and form a dense film under vacuum. This AD process eliminates high temperature processing thereby enabling new coatings and device integration, in which ceramics can be deposited on metals, plastics, and glass. However, knowledge in fundamental mechanisms for ceramic particles to deform and form a dense ceramic film is still needed and is essential in advancing this novel RT technology. In this work, a combination of experimentation and atomistic simulation was used to determine the deformation behavior of sub-micron sized ceramic particles; this is the first fundamental step needed to explain coating formation in the AD process. High purity, single crystal, alpha alumina particles with nominal sizes of 0.3 µm and 3.0 µm were examined. Particle characterization, using transmission electron microscopy (TEM), showed that the 0.3 µm particles were relatively defect-free single crystals whereas 3.0 µm particles were highly defective single crystals or particles contained low angle grain boundaries. Sub-micron sized Al 2 O 3 particles exhibited ductile failure in compression. In situ compression experiments showed 0.3µm particles deformed plastically, fractured, and became polycrystalline. Moreover, dislocation activity was observed within these particles during compression. These sub-micron sized Al 2 O 3 particles exhibited large accumulated strain (2-3 times those of micron-sized particles) before first fracture. In agreement with the findings from experimentation, atomistic simulations of nano-Al 2 O 3 particles showed dislocation slip and significant plastic deformation during compression. On the other hand, the micron sized Al 2 O 3 particles exhibited brittle fracture in compression. In situ compression experiments showed 3µm Al 2 O 3 particles fractured into pieces without observable plastic deformation in compression. Particle deformation behaviors will be used to inform Al 2 O 3 coating deposition parameters and particle-particle bonding in the consolidated Al 2 O 3 coatings.

Sarobol, Pylin↗