Advanced Processing and Environmental Barrier Coating System Development for SiC/SiC Ceramic Matrix Composites
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Zhu, Dongming↗
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High-Temperature Ceramic Capacitors for Applications in Deep Drilling and Completion Processes
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03 NATURAL GAS↗
Development of a High Strength, High Modulus Ceramic Fiber Final Summary Report, 29 Jun. 1967 - 29 Sep. 1968
Salt decomposition process for production of high strength ceramic continuous fiber
Fetterolf, R. N.↗
Commercialization of Ultra-Hard Ceramics for Cutting Tools Final Report CRADA No. TC0279.0
This was a collaborative effort between Lawrence Livermore National Security, LLC as manager and operator of Lawrence Livermore National Laboratory (LLNL) and Greenleaf Corporation (Greenleaf) to develop the technology for forming unique precursor nano-powders process that can be consolidated into ceramic products for industry. LLNL researchers have developed a solgel process for forming nano-ceramic powders. The nano powders are highly tailorable, allowing the explicit design of desired properties that lead to ultra hard materials with fine grain size. The present CRADA would allow the two parties to continue the development of the sol-gel process and the consolidation process in order to develop an industrially sound process for the manufacture of these ultra-hard materials.
36 MATERIALS SCIENCE↗
Applying molecular dynamics simulations to the study of micro cold spray of yttria
Micro cold spray (MCS) is a novel manufacturing process with proven success depositing dense, thick films of technical ceramics without the need for elevated processing temperatures or chemical precursors. The process transforms a loose sub-micrometer powder into an adherent film with mechanical properties approaching that of the bulk material through a phenomenon known as room temperature impact consolidation. While this phenomenon has been demonstrated for a wide variety of ceramic materials and film substrates, yttria stands out as a material that is both well-characterized in experiments and of significant interest for industrial applications due to its excellent refractory properties. This dissertation seeks to investigate the fundamental mechanisms that enable room temperature impact consolidation by using molecular dynamics (MD) simulations of yttria particle impacts and characterizing the deformation behavior of the system.
36 MATERIALS SCIENCE↗
Development of Ceramic Solid-State Laser Host Material
Polycrystalline ceramic laser materials are gaining importance in the development of novel diode-pumped solid-state lasers. Compared to single-crystals, ceramic laser materials offer advantages in terms of ease of fabrication, shape, size, and control of dopant concentrations. Recently, we have developed Neodymium doped Yttria (Nd:Y2O3) as a solid-state ceramic laser material. A scalable production method was utilized to make spherical non agglomerated and monodisperse metastable ceramic powders of compositions that were used to fabricate polycrystalline ceramic material components. This processing technique allowed for higher doping concentrations without the segregation problems that are normally encountered in single crystalline growth. We have successfully fabricated undoped and Neodymium doped Yttria material up to 2" in diameter, Ytterbium doped Yttria, and erbium doped Yttria. We are also in the process of developing other sesquioxides such as scandium Oxide (Sc2O3) and Lutesium Oxide (Lu2O3) doped with Ytterbium, erbium and thulium dopants. In this paper, we present our initial results on the material, optical, and spectroscopic properties of the doped and undoped sesquioxide materials. Polycrystalline ceramic lasers have enormous potential applications including remote sensing, chem.-bio detection, and space exploration research. It is also potentially much less expensive to produce ceramic laser materials compared to their single crystalline counterparts because of the shorter fabrication time and the potential for mass production in large sizes.
Prasad, Narasimha S.↗
Steric stabilization of nonaqueous silicon slips. I - Control of particle agglomeration and packing. II - Pressure casting of powder compacts
The application of steric stabilization to control particle agglomeration and packing of silicon powder in benzene and trichloroethylene is reported. The results provide useful guidelines for controlling unfavorable particle-particle interactions during nonaqueous processing of silicon-based ceramic materials. The application of steric stabilization to the control and improvement of green processing of nonaqueous silicon slips in pressure consolidation is also demonstrated.
Kerkar, Awdhoot V.↗
Study of Ion Conductivity and Chain Dynamics in Polymer-Ceramic Composite Electrolytes
We fabricated polymer-ceramic composite consisting of polyethylene oxide, lithium trifluoromethanesulfonate, and a lithium-conducting glass ceramic from Ohara corporation. We examined the ion conductivity of the composite electrolyte with high volume fractions of Ohara ceramic (30% to 60%) using various processing methods. In this composition range, the composite conductivity was less affected by the volume fraction of the ceramic. Instead, it was strongly affected by processing methods. We found that the composite showed lower ion conductivity than the conductivity of PEO and the Ohara ceramic. A trilayer experiment using polymer electrolyte/Ohara ceramic plate/polymer electrolyte design revealed a very large interfacial resistance between the polymer electrolyte and Ohara ceramic. Quasi-elastic neutron scattering measurements were performed on the system to shed light on underpinnings of the origin of this large interfacial resistance.
Chen, Xi↗
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↗
Development of high strength, high temperature ceramics
Improvement in the high-pressure turbopumps, both fuel and oxidizer, in the Space Shuttle main engine were considered. The operation of these pumps is limited by temperature restrictions of the metallic components used in these pumps. Ceramic materials that retain strength at high temperatures and appear to be promising candidates for use as turbine blades and impellers are discussed. These high strength materials are sensitive to many related processing parameters such as impurities, sintering aids, reaction aids, particle size, processing temperature, and post thermal treatment. The specific objectives of the study were to: (1) identify and define the processing parameters that affect the properties of Si3N4 ceramic materials, (2) design and assembly equipment required for processing high strength ceramics, (3) design and assemble test apparatus for evaluating the high temperature properties of Si3N4, and (4) conduct a research program of manufacturing and evaluating Si3N4 materials as applicable to rocket engine applications.
Hall, W. B.↗
Scalable Solution-Processed Electrolyte Membranes with Optimized Microstructure for High-Performance Protonic Ceramic Electrochemical Cells
Proton-conducting electrochemical cells (PCECs) are promising for efficient hydrogen production, but achieving dense, uniform, thin electrolyte layers remains a key challenge, particularly for scalable fabrication. Here, we present a solution-processed deposition approach with a mechanistically optimized slurry for uniform electrolyte formation. By tailoring particle size distribution, solid loading, and solvent/additive balance, we regulated wetting behavior and evaporation kinetics of the electrolyte slurry to promote homogeneous electrolyte particle packing. These features facilitate tight grain boundary contact and early stage neck growth during sintering, eliminating residual porosity, and improving mechanical integrity. The resulting ∼15 μm thick electrolyte shows high density, strong electrode adhesion, and stable interfaces outperforming the previously reported spray-based fabricated electrolyte by about 31% at 600 °C in FC mode. Single cells deliver 0.962 W cm –2 at 600 °C in fuel cell mode and 1.31 A cm –2 at 1.3 V in electrolysis mode, maintaining robust performance over 100 h with negligible degradation (≤0.02% h –1 ) in each mode. Scale-up to 2.5 cm diameter substrates confirmed reproducible densification and geometric stability. This work demonstrates a cost-effective, scalable route where control over particle-fluid interactions and drying dynamics enables a superior electrolyte microstructure and high PCEC performance.
dense microstructure↗
Cold sintering process of Li 1.5 Al 0.5 Ge 1.5 (PO 4 ) 3 solid electrolyte
Abstract The recently developed technique of cold sintering process (CSP) enables densification of ceramics at low temperatures, i.e., <300°C. CSP employs a transient aqueous solvent to enable liquid phase‐assisted densification through mediating the dissolution‐precipitation process under a uniaxial applied pressure. Using CSP in this study, 80% dense Li 1.5 Al 0.5 Ge 1.5 (PO 4 ) 3 (LAGP) electrolytes were obtained at 120°C in 20 minutes. After a 5 minute belt furnace treatment at 650°C, 50°C above the crystallization onset, Li‐ion conductivity was 5.4 × 10 −5 S/cm at 25°C. Another route to high ionic conductivities ~10 −4 S/cm at 25°C is through a composite LAGP ‐ (PVDF‐HFP) co‐sintered system that was soaked in a liquid electrolyte. After soaking 95, 90, 80, 70, and 60 vol% LAGP in 1 M LiPF 6 EC‐DMC (50:50 vol%) at 25°C, Li‐ion conductivities were 1.0 × 10 −4 S/cm at 25°C with 5 to 10 wt% liquid electrolyte. This paper focuses on the microstructural development and impedance contributions within solid electrolytes processed by (i) Crystallization of bulk glasses, (ii) CSP of ceramics, and (iii) CSP of ceramic‐polymer composites. CSP may offer a new route to enable multilayer battery technology by avoiding the detrimental effects of high temperature heat treatments.
Berbano, Seth S.↗
Dielectric and piezoelectric properties of 0.970(0.95(K{sub 0.485}Na{sub 0.515})NbO{sub 3}–0.05LiSbO{sub 3})–0.015CuO–0.015Al{sub 2}O{sub 3}/PVDF 0–3 composite reinforced with two kinds of ZnO powder
0.970(0.95(K{sub 0.485}Na{sub 0.515})NbO{sub 3}–0.05LiSbO{sub 3})–0.015CuO–0.015Al{sub 2}O{sub 3} (KNNLS–CA) ceramic powder obtained through the conventional solid state reaction. The ZnO nanoparticles (denoted as ZnO1) and poly (vinylidene fluoride) (PVDF) were supplied from commercial companies. The self-synthesized ZnO powder (denoted as ZnO2) were prepared by hydrothermal method using Zn (CH{sub 3}COO){sub 2}·2H{sub 2}O and NaOH. Subsequently, the two kinds of composites were fabricated by hot-pressing process using KNNLS–CA ceramic powder, two kinds of ZnO powder and PVDF polymer. The effects of the ZnO on the crystalline structures, morphology, thermal stability, densities and electric properties of composites were studied systemically. The KNNLS–CA ceramic possesses a perovskite phase with orthorhombic symmetry and peaks from the second phase of K{sub 3}Li{sub 2}Nb{sub 5}O{sub 15} (PDF#52-0157) are detected by X-ray diffraction. PVDF polymer mainly possesses α, β and γ phases. Two kinds of ZnO all possess hexagonal wurtzite structures without any impurity phase. It is worth noting that the ZnO particles have great impacts on lattice constants, strain and crystallinity. In addition, the ZnO particles can enhance the relative fraction of β phase in PVDF and improve the thermal stability of the composite. Interestingly, the dielectric and piezoelectric properties are also found to be improved with the increase of ZnO content. Especially, when 10 wt.% ZnO2 is doped, the dielectric permittivity reaches the value of 586.4 (100 Hz) at room temperature and the piezoelectric constant is 64 pC/N. After 30 days of aging test, it is obvious that all the composites present a good stability of piezoelectric property.
77 NANOSCIENCE AND NANOTECHNOLOGY↗
Processing and consolidation of copper/tungsten
Here, we developed a copper/tungsten (Cu/W) composite for mesoscale Materials Science applications using the novel High-Energy Diffraction Microscopy (HEDM) technique. Argon-atomized copper powder was selected as the starting raw powder and screened to remove the extremely large particle fraction. Tungsten particles were collected by milling and screening the -325 mesh tungsten powder between 500 and 635 mesh sieves. Hot pressing of screened Cu powder was performed at 900 °C in Ar/4 %H 2 atmosphere. XRD and ICP results show that the hot-pressed Cu sample consists of about 5 vol% Cu 2 O, which is caused by the presence of oxygen on the surface of the starting Cu powder. Hot pressing the copper powder in a pure hydrogen atmosphere was successful in removing most of the surface oxygen. Our process was also implemented for hot pressing the Cu/W composite. The density of the Cu/W composites hot pressed at 950 °C in pure hydrogen was about 94 % of the theoretical density (TD). The hot-pressed Cu/W composites were further hot isostatic pressed at 1050 °C in argon atmosphere, which results in 99.6 % of the TD with the designed Cu grain size and W particle distribution. Tensile specimens with D-notch were machined using the wire EDM method. Furthermore, the processing and consolidation of these materials will be discussed in detail. The HEDM images are also showed and discussed.
36 MATERIALS SCIENCE↗
Progress and Technology Assessment of Melt-Cast Ceramic Waste Forms
The Savannah River National Laboratory (SRNL) conducted research from FY2011 – FY2020 to develop ceramic waste forms to treat High-Level Waste (HLW) resulting from reprocessing of commercial Used Nuclear Fuel (UNF) as part of the Department of Energy (DOE) office of Nuclear Energy (NE) Fuel Cycle Technologies (FCT) research program. The objective of the research was to develop a reference ceramic waste form and process technology needed to immobilize the combined HLW raffinate stream, including undissolved solids and soluble technetium, and potentially the TRU waste stream resulting from reprocessing processes. This report compiles the relevant literature produced under, and pertinent to, the program objectives and provides a perspective on the technology development as well as prospects for future.
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
Superconductivity devices: Commercial use of space
The work described in this report covers various aspects of the Rainbow solid-state actuator technology. It is presented in six parts dealing with materials, processing, fabrication, properties and associated phenomena. The Rainbow actuator technology is a relatively new materials development which had its inception in 1992. It consists of a new processing technology for preparing piezoelectric and electrostrictive ceramic materials. It involves a high temperature chemical reduction process which leads to an internal pre-stressing of the oxide wafer, thus the name Rainbow, an acronym for Reduced And INternally Biased Oxide Wafer. Ceramics fabricated by this method produce bending-mode actuator devices which possess several times more displacement and load bearing capacity than present-day benders (unimorphs, bimorphs). It is anticipated that these solid-state, electromechanical actuators which can be used in a number of applications in space such as cryopump motors, anti-vibration active structures, autoleveling platforms, telescope mirror correctors and autofocusing devices. When considering any of these applications, the key to the development of a successful device is the successful development of a ceramic material which can produce maximum displacement per volt input; hence, this initiative involving a solid-state means for achieving unusually high electromechanical displacement can be significant and far reaching. An additional benefit obtained from employing the piezoelectric effect in these actuator devices is the ability to also utilize them as sensors; and, indeed, they can be used as both motor (actuator) and generator (sensor) in multifunction devices.
Haertling, Gene↗
X-ray characterization technique for the assessment of surface damage in GaN wafers
SixPoint Materials has successfully switched to production of two-inch diameter GaN wafers using the ammonothermal method. Crystal quality values are high with dislocation densities typically in the low 10 5 cm -2 . In efforts to produce true epi-ready material, investigations were made to develop a technique to study surface damage caused by the back-end process using X-ray diffraction methods. Analysis of peak tailing from X-ray rocking curves of the (1 1 4) reflection indicates the progression of surface damage during each step of the back-end process. For instance, the tailing can be partially represented using full width five thousand max (FW5000M) values. By using a peak with a low glancing angle, such as the (1 1 4) reflection’s angle of 10.8662°, more of the X-ray beam is scattered in the surface region, providing an improved measurement of surface damage. Since this technique is non-destructive and can be performed without dismounting the sample from its ceramic back-end processing plate, it can provide information on the damaged layer at each stage of the back-end process. Using this technique to evaluate samples from various manufacturers, we found a lack of uniformity in surface damage from GaN companies. It is our hope that this technique will be adopted to better standardize surface damage measurements in the GaN field.
36 MATERIALS SCIENCE↗
Ceramics for Molten Materials Containment, Transfer and Handling on the Lunar Surface
As part of a project on Molten Materials Transfer and Handling on the Lunar Surface, molten materials containment samples of various ceramics were tested to determine their performance in contact with a melt of lunar regolith simulant. The test temperature was 1600 C with contact times ranging from 0 to 12 hours. Regolith simulant was pressed into cylinders with the approximate dimensions of 1.25 dia x 1.25cm height and then melted on ceramic substrates. The regolith-ceramic interface was examined after processing to determine the melt/ceramic interaction. It was found that the molten regolith wetted all oxide ceramics tested extremely well which resulted in chemical reaction between the materials in each case. Alumina substrates were identified which withstood contact at the operating temperature of a molten regolith electrolysis cell (1600 C) for eight hours with little interaction or deformation. This represents an improvement over alumina grades currently in use and will provide a lifetime adequate for electrolysis experiments lasting 24 hours or more. Two types of non-oxide ceramics were also tested. It was found that they interacted to a limited degree with the melt resulting in little corrosion. These ceramics, Sic and BN, were not wetted as well as the oxides by the melt, and so remain possible materials for molten regolith handling. Tests wing longer holding periods and larger volumes of regolith are necessary to determine the ultimate performance of the tested ceramics.
Standish, Evan↗