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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 37 records · Page 2

System and method for light assisted friction stir processing and welding of metallic and non-metallic materials

An apparatus for use in a friction stir operation, such as friction stir welding (FSW) or friction stir processing (FSP). The apparatus may have a rotating tool adapted to be plunged into a material, where the material is susceptible to being softened by heating. The rotating tool may further be adapted to be advanced along a surface of the material. An optical energy generating subsystem may be used to heat a portion of the material using optical energy as the tool is advanced along the material.

42 ENGINEERING↗

From n- to p-type material: Effect of Metal Ion on Charge Transport in Metal-Organic Materials

An intriguing new class of two-dimensional (2D) materials based on metal–organic frameworks (MOFs) has recently been developed that displays electrical conductivity, a rarity among these nanoporous materials. The emergence of conducting MOFs raises questions about their fundamental electronic properties, but few studies exist in this regard. Here, we present an integrated theory and experimental investigation to probe the effects of metal substitution on the charge transport properties of M-HITP, where M = Ni or Pt and HITP = 2,3,6,7,10,11-hexaiminotriphenylene. The results show that the identity of the M-HITP majority charge carrier can be changed without intentional introduction of electronically active dopants. We observe that the selection of the metal ion substantially affects charge transport. Using the known structure, Ni-HITP, we synthesized a new amorphous material, a-Pt-HITP, which although amorphous is nevertheless found to be porous upon desolvation. Importantly, this new material exhibits p-type charge transport behavior, unlike Ni-HITP, which displays n-type charge transport. These results demonstrate that both p- and n-type materials can be achieved within the same MOF topology through appropriate choice of the metal ion.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Charge Compensation by Iodine Covalent Bonding in Lead Iodide Perovskite Materials

Metal halide perovskite materials (MHPs) are a family of next-generation semiconductors that are enabling low-cost, high-performance solar cells and optoelectronic devices. The most-used halogen in MHPs, iodine, can supplement its octet by covalent bonding resulting in atomic charges intermediate to I− and I0. Here, we examine theoretically stabilized defects of iodine using density functional theory (DFT); defect formation enthalpies and iodine Bader charges which illustrate how MHPs adapt to stoichiometry changes. Experimentally, X-ray photoelectron spectroscopy (XPS) is used to identify perovskite defects and their relative binding energies, and validate the predicted chemical environments of iodine defects. Examining MHP samples with excess iodine compared with near stoichiometric samples, we discern additional spectral intensity in the I 3d5/2 XPS data arising from defects, and support the presence of iodine trimers. I 3d5/2 defect peak areas reveal a ratio of 2:1, matching the number of atoms at the ends and middle of the trimer, whereas their binding energies agree with calculated Bader charges. Results suggest the iodine trimer is the preferred structural motif for incorporation of excess iodine into the perovskite lattice. Understanding these easily formed photoactive defects and how to identify their presence is essential for stabilizing MHPs against photodecomposition.

36 MATERIALS SCIENCE↗

Report on PTT Imaging of Defects in AM Metallic Materials-Part 2

Metal Additive Manufacturing (AM) is a promising method for cost-efficient fabrication of complex shape structures for applications in harsh environment, such as in a nuclear reactor. However, internal defects (pores) occur in high-strength AM alloys, which are manufactured with Laser Powder Bed Fusion (LPBF) AM method. Pulsed Infrared Thermography (PIT) is an efficient nondestructive evaluation (NDE) method to examine actual structures, because this method offers one-sided non-contact measurements, and fast processing of large sample areas. However, imaging of material defects, particularly defects with sizes at microscopic level, is challenging. In this report, we benchmark the performance of several Unsupervised Learning (UL) algorithms designed to enhance imaging of microscopic defects in metals with PIT. UL aims to learn the latent principal patterns (dictionaries) in PIT data to detect defects with minimal human supervision. Performance of Independent Component Analysis (ICA), Sparse Coding (SC), Principal Component Analysis (PCA) and Exploratory Factor Analysis (EFA) was compared using F-score, UL model training time and defects reconstruction time. We obtained the average F-score of 0.75, and a highest F-score of 0.89 for the EFA algorithm. Overall, EFA outperforms other UL algorithms considered in this study.

36 MATERIALS SCIENCE↗

Optical sensor employing a refractive index engineered metal oxide material

An optical sensor device includes an optical waveguide portion having a core, the core having a first refractive index, and a functional material layer coupled to the optical fiber portion, the functional material layer being made of a metal oxide material, the functional material layer being structured to have a second refractive index, the second refractive index being less than the first refractive index. The functional material layer may be a nanostructure material comprising the metal oxide material with a plurality of holes or voids formed therein such that the functional material layer is caused to have the second refractive index.

Chen, Peng↗

Critical Review of Platinum Group Metal-Free Materials for Water Electrolysis: Transition from the Laboratory to the Market : Earth-abundant borides and phosphides as catalysts for sustainable hydrogen production

To combat the global problem of carbon dioxide emissions, hydrogen is the desired energy vector for the transition to environmentally benign fuel cell power. Water electrolysis (WE) is the major technology for sustainable hydrogen production. Despite the use of renewable solar and wind power as sources of electricity, one of the main barriers for the widespread implementation of WE is the scarcity and high cost of platinum group metals (pgms) that are used to catalyse the cathodic hydrogen evolution reaction (HER) and the anodic oxygen evolution reaction (OER). Hence, the critical pgm-based catalysts must be replaced with more sustainable alternatives for WE technologies to become commercially viable. This critical review describes the state-of-the-art pgm-free materials used in the WE application, with a major focus on phosphides and borides. Several emerging classes of HER and OER catalysts are reviewed and detailed structure-property correlations are comprehensively summarised. The influence of the crystallographic and electronic structures, morphology and bulk and surface chemistry of the catalysts on the activity towards OER and HER is discussed.

Chemistry↗

Metallic glass coating material

A metallic glass coating material is composed of an alloy of Fe, B, and one of the metals Nb, Mo, Zr, or W. The ratios of Fe, B, and the metal are predetermined using machine learning predictions and high-throughput experiments. In one example, the material is an alloy of Fe, Nb, Mo and B, of the form Fe x (Nb, Mo) y B z , where x is in the range 18-28, y is in the range 35-45, and z is in the range 32-42. In another example, the material may be the alloy Fe 23 (Nb, Mo) 40 B 37 . The alloy may be doped with Zr and/or W, where the Zr and/or W comprises at most 10% of the alloy.

Mehta, Apurva↗

Electrical Control of Magnetic Resonance in Phase Change Materials

Metal–insulator transitions (MITs) in resistive switching materials can be triggered by an electric stimulus that produces significant changes in the electrical response. When these phases have distinct magnetic characteristics, dramatic changes in the spin excitations are also expected. The transition metal oxide La 0.7 Sr 0.3 MnO 3 (LSMO) is a ferromagnetic metal at low temperatures and a paramagnetic insulator above room temperature. When LSMO is in its metallic phase, a critical electrical bias has been shown to lead to an MIT that results in the formation of a paramagnetic resistive barrier transverse to the applied electric field. Using spin-transfer ferromagnetic resonance spectroscopy, we show that even for electrical biases less than the critical value that triggers the MIT, there is magnetic phase separation, with the spin-excitation resonances varying systematically with applied bias. Therefore, voltage-triggered MITs in LSMO can alter magnetic resonance characteristics, offering an effective method for tuning synaptic weights in neuromorphic circuits.

36 MATERIALS SCIENCE↗

Methods for producing metal carbide materials

Methods of producing silicon carbide, and other metal carbide materials. The method comprises reacting a carbon material (e.g., fibers, or nanoparticles, such as powder, platelet, foam, nanofiber, nanorod, nanotube, whisker, graphene (e.g., graphite), fullerene, or hydrocarbon) and a metal or metal oxide source material (e.g., in gaseous form) in a reaction chamber at an elevated temperature ranging up to approximately 2400° C. or more, depending on the particular metal or metal oxide, and the desired metal carbide being produced. A partial pressure of oxygen in the reaction chamber is maintained at less than approximately 1.01×102 Pascal, and overall pressure is maintained at approximately 1 atm.

Garnier, John E.↗

System and method of making a cast steel alloy crankshaft having low porosity

Systems and methods of making a cast steel alloy crankshaft for an internal combustion engine are provided. The method comprises providing a mold of the crankshaft. The mold has cavities to form the crankshaft. The method further comprises melting a first metallic material at between 1400 degrees Celsius (° C.) and 1600° C. to define a molten metallic material. In addition, the method further comprises feeding the molten metallic material at a riser connection angle of between 30° and 75° in the cavities of the negative sand cast mold. The method further comprises cooling the molten metallic material at a solidification time of between 5 seconds (sec) and 20 sec in the negative sand cast mold with at least one chill member to define a solidified metallic material having dimensions of the cast steel alloy crankshaft. Furthermore, the method comprises separating the solidified metallic material from the negative sand cast mold to define the cast steel alloy crankshaft.

Wang, Liang↗

Review of Layered Transition Metal Oxide Materials for Cathodes in Sodium-Ion Batteries

The growing interest in sodium-ion batteries (SIBs) is driven by scarcity and the rising costs of lithium, coupled with the urgent need for scalable and sustainable energy storage solutions. Among various cathode materials, layered transition metal oxides have emerged as promising candidates due to their structural similarity to lithium-ion battery (LIB) counterparts and their potential to deliver high energy density at reduced costs. However, significant challenges remain, including limited capacity at high charge/discharge rates and structural instability during extended cycling. Addressing these issues is critical for advancing SIB technology toward industrial applications, particularly for large-scale energy storage systems. This review provides a comprehensive analysis of layered sodium transition metal oxides, focusing on their structural properties, electrochemical performance, and degradation mechanisms. Special attention is given to the intrinsic and extrinsic factors contributing to their instability, such as structural phase transitions, and cationic/anionic redox behavior. Additionally, recent advancements in material design strategies, including doping, surface modifications, and composite formation, are discussed to highlight the progress toward enhancing the stability and performance of these materials. This work aims to bridge the knowledge gaps and inspire further innovations in the development of high-performance cathodes for sodium-ion batteries.

Ahangari, Mehdi (ORCID:0000000345803969)↗

Sequential separation of battery electrode materials and metal foils in aqueous media

To recycle high-value lithium-ion battery components, it is imperative to efficiently separate electrode materials from current collector foils and to separate cathodes from anodes. This study investigates the delamination behaviors of cathodes and anodes from their respective current collectors in aqueous media. Whereas anode films can easily detach from copper foils in water, the delamination of cathode films does not exhibit the same behavior in water; instead, the cation exchange reaction results in lithium leaching and aluminum corrosion in the presence of water. Here, a buffer solution with surfactant additives has been designed to prevent aluminum corrosion and to improve solution wetting behavior, thereby facilitating cathode delamination. The delamination difference enables the sequential recovery of electrode materials and metal foils at different separation stages, simplifying the traditionally intricate processes within a one-pot recovery system. The recovered materials retain their crystal structure and morphology, and there are no signs of aluminum corrosion or residues on the metal foils. The sequential separation technique achieves nearly 100% separation efficiency for electrode materials from metal foils and over 98% separation efficiency for cathode and anode materials.

25 ENERGY STORAGE↗