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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 1,099 records · Page 61
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Bond Wire Damage Detection and State of Health Estimation of a 1200V, 900A Dual Pack IGBT Power Module using the RL-Equivalent Circuit

Electrical and environmental stresses are the two dominant contributors in aging and failure of power semiconductor devices. Insulated gate bipolar junction transistors (IGBTs) and metal-oxide semiconductor field effect transistors (MOSFETs) are two most commonly used switching devices in power converter circuits. A significant portion of research effort is given in inventing innovative methods to estimate the degradation and fatigue in these devices. Until today, no other existing techniques can determine the number of lifted bond wires and their locations in a live IGBT module, although this information is extremely helpful to understand the overall state of health of an IGBT power module. In this paper, we have proposed a reflectometry-based technique to overcome this hurdle. The RL-equivalent circuit to represent a bond wire has been developed for the device under test and simulated in CST Studio Suite to measure the reflection amplitudes. Experimental results were obtained using a prototype reflectometry hardware, and both the simulation and experimental results have been compared. These results prove that with these two sets of measurements, it is possible to locate the aged device inside a module and detect the number of bond wire lift-offs associated to that device.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2022

Atmospheric Cold Plasma Jet Coating and Surface Treatment for Improved Adhesive Bonding Performance of Dissimilar Material Joints Subject to Harsh Environmental Exposure

The program goal was the development and demonstration of a novel material coating system using an innovative atmospheric cold microwave plasma jet to enable surface functionalization for corrosion protection, wear resistance and improved bonding strength. The technical approach was directed towards proof-of-concept demonstration of advanced point-of-manufacturing material bonding to improve adhesive joint performance subject to harsh environmental exposure. The assembled team, consisting of the researchers at the University of Illinois, end-users at General Motors and small business manufacturer Starfire Industries, successfully demonstrated a single, cost-effective, high-volume production process that meets the requirements of multi-material combinations relevant to the energy-intensive transportation industry (e.g. Al-steel, Mg-steel, Al-Mg and Al-CFRP joints for body-in-white structures) while eliminating offline pretreatment for Al and Mg alloy substrates that are energy intensive, have chemical waste disposal issues, and add cost. Technical demonstration of dissimilar material joining while maintaining bonding strength and cohesion after long-duration environmental exposure was accomplished for all materials of interest. This novel approach has broad applicability for manufacturing in automotive, aerospace, marine, railcar, and specialty consumer goods, etc.

36 MATERIALS SCIENCE↗
DOE OSTI2019

The Effect of Pressure on Halogen Bonding in 4-Iodobenzonitrile

The crystal structure of 4-iodobenzonitrile, which is monoclinic (space group I2/a) under ambient conditions, contains chains of molecules linked through C≡N···I halogen-bonds. The chains interact through CH···I, CH···N and π-stacking contacts. The crystal structure remains in the same phase up to 5.0 GPa, the b axis compressing by 3.3%, and the a and c axes by 12.3 and 10.9 %. Since the chains are exactly aligned with the crystallographic b axis these data characterise the compressibility of the I···N interaction relative to the inter-chain interactions, and indicate that the halogen bond is the most robust intermolecular interaction in the structure, shortening from 3.168(4) at ambient pressure to 2.840(1) Å at 5.0 GPa. The π∙∙∙π contacts are most sensitive to pressure, and in one case the perpendicular stacking distance shortens from 3.6420(8) to 3.139(4) Å. Packing energy calculations (PIXEL) indicate that the π∙∙∙π interactions have been distorted into a destabilising region of their potentials at 5.0 GPa. The structure undergoes a transition to a triclinic ( P 1 ¯ ) phase at 5.5 GPa. Over the course of the transition, the initially colourless and transparent crystal darkens on account of formation of microscopic cracks. The resistance drops by 10% and the optical transmittance drops by almost two orders of magnitude. The I···N bond increases in length to 2.928(10) Å and become less linear [

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1994

Nondestructive Characterization of Adhesive Bonds from Guided Wave Data

The critical role played by adhesive bonds in the fracture and failure of composites and other bonded materials is well known. A good knowledge of the mechanical properties of these adhesion joints is a prerequisite to reliable design and reliable prediction of the performance of these bonded structures.

moduli↗
NASA NTRS2011

Temperature Effects on Adhesive Bond Strengths and Modulus for Commonly Used Spacecraft Structural Adhesives

A study was performed to observe how changes in temperature and substrate material affected the strength and modulus of an adhesive bondline. Seven different adhesives commonly used in aerospace bonded structures were tested. Aluminum, titanium and Invar adherends were cleaned and primed, then bonded using the manufacturer's recommendations. Following surface preparation, the coupons were bonded with the adhesives. The single lap shear coupons were then pull tested per ASTM D 1002 Standard Test Method for Apparent Shear Strength of Single- Lap-Joint over a temperature range from -150 deg C up to +150 deg C. The ultimate strength was calculated and the resulting data were converted into B-basis design allowables. Average and Bbasis results were compared. Results obtained using aluminum adherends are reported. The effects of using different adherend materials and temperature were also studied and will be reported in a subsequent paper. Dynamic Mechanical Analysis (DMA) was used to study variations in adhesive modulus with temperature. This work resulted in a highly useful database for comparing adhesive performance over a wide range of temperatures, and has facilitated selection of the appropriate adhesive for spacecraft structure applications.

structural adhesives testing↗
NASA NTRS2024

Out of Plane Stresses Using a Beam-Based Elastic Foundation Bonded Joint Model

Efficient, semi-analytical models of bonded joints are utilized for initial joint design and sizing due to their convenience and speed. Many of these models are based on beam and plate theories, which are most applicable when in-plane stresses/strains dominate. While this can be a sensible assumption for obtaining the deformations of the joint, out of plane (transverse) stresses are often of critical importance for failure in bonded joints composed of fiber reinforced composite materials. Since through-thickness strains are neglected in these semi-analytical theories, the present study shows a method to back-calculate the out of plane stresses based on stress balance equations, which use the in-plane stresses and displacements that have already been obtained. The method was implemented within the Joint Element Designer (JED) software, and verification and validation examples have been shown. As is typical for these types of models, corner stress singularities are not captured by the JED model, but the general trends of the stress and deformation fields agreed with a higher fidelity finite element model. As such, this method for obtaining out of plane stresses, when coupled with the JED code, is very useful for the complete stress analysis of bonded composite joints.

composites↗
NASA NTRS2026

Beyond Melting: Amorphous Bonding for Joining and Consolidation

Crystallization may be the hidden constraint in thermoplastic composite manufacturing. It requires tightly controlled cooling, induces residual stresses through shrinkage, and introduces path-dependent behavior that complicates predictive modeling yet remains essential for structural performance. This work asks: can bonding be achieved without relying on melt-driven crystallization? To address this, thin (5–20 μm) polyetherimide (PEI) interlayers are pre-healed to slow-cooled polyaryletherketone (PAEK) in two contexts. The first, Thermabond®, is sub-melt joining of low melt-PAEK laminates. Results show that bond quality is governed primarily by processing (i.e., adequate healing and film handling) rather than modest changes in interlayer thickness. This concept is then extended to laminate-scale manufacturing through an architecture known as OATMEAL (Out-of-autoclave Amorphous/semicrystalline Thermoplastic Material for Energy-efficient Aerospace-grade Laminates). PEI is healed to carbon fiber reinforced polyetheretherketone (PEEK) at the prepreg and excess PEI is then ablated from the surface. Crystallinity is developed off-line during prepreg fabrication, while subsequent consolidation occurs below the melt temperature to preserve it. Cross-ply warpage experiments show that, contrary to intuition, repeated amorphous interfaces reduce global curvature by lowering the effective stress lock-in temperature and eliminating crystallization shrinkage from the lamina response. Correspondingly, laminate behavior is accurately predicted using classical laminate theory (CLT) with a single effective stress-free temperature, whereas conventional CF/PEEK requires accounting for crystallization-driven effects. By decoupling interfacial healing from crystallization, OATMEAL enables sub-melt consolidation, reduces energy consumption by up to 75%, and increases manufacturing throughput by fivefold. These results demonstrate that amorphous bonding is not only a joining strategy, but a pathway to more predictable and scalable thermoplastic composite manufacturing.

solidification↗
DOE OSTI2021

Accelerated Discovery and Design of Ultralow Lattice Thermal Conductivity Materials Using Chemical Bonding Principles

Semiconductors with very low lattice thermal conductivities are highly desired for applications relevant to thermal energy conversion and management, such as thermoelectrics and thermal barrier coatings. Although the crystal structure and chemical bonding are known to play vital roles in shaping heat transfer behavior, material design approaches of lowering lattice thermal conductivity using chemical bonding principles are uncommon. In this work, an effective strategy of weakening interatomic interactions and therefore suppressing lattice thermal conductivity based on chemical bonding principles is presented and a high-efficiency approach of discovering low κ L materials by screening the local coordination environments of crystalline compounds is developed. The resulting first-principles calculations uncover 30 hitherto unexplored compounds with (ultra)low lattice thermal conductivities from 13 prototype crystal structures contained in the Inorganic Crystal Structure Database. Furthermore, an approach of rationally designing high-performance thermoelectrics is demonstrated by additionally incorporating cations with stereochemically active lone-pair electrons. Here these results not only provide atomic-level insights into the physical origin of the low lattice thermal conductivity in a large family of copper/silver-based compounds but also offer an efficient approach to discover and design materials with targeted thermal transport properties.

36 MATERIALS SCIENCE↗
DOE OSTI2017

A Metal–Organic Framework with Exceptional Activity for C−H Bond Amination

Abstract The development of catalysts capable of fast, robust C−H bond amination under mild conditions is an unrealized goal despite substantial progress in the field of C−H activation in recent years. A Mn‐based metal–organic framework (CPF‐5) is described that promotes the direct amination of C−H bonds with exceptional activity. CPF‐5 is capable of functionalizing C−H bonds in an intermolecular fashion with unrivaled catalytic stability producing >10 5 turnovers.

Wang, Le↗
DOE OSTI2020

Dissipative Assembly of Macrocycles Comprising Multiple Transient Bonds

Abstract Dissipative assembly has great potential for the creation of new adaptive chemical systems. However, while molecular assembly at equilibrium is routinely used to prepare complex architectures from polyfunctional monomers, species formed out of equilibrium have, to this point, been structurally very simple. In most examples the fuel simply effects the formation of a single short‐lived covalent bond. Herein, we show that chemical fuels can assemble bifunctional components into macrocycles containing multiple transient bonds. Specifically, dicarboxylic acids give aqueous dianhydride macrocycles on treatment with a carbodiimide. The macrocycles are assembled efficiently as a consequence of both fuel‐dependent and fuel‐independent mechanisms; they undergo slower decomposition, building up as the fuel recycles the components, and are a favored product of the dynamic exchange of the anhydride bonds. These results create new possibilities for generating structurally sophisticated out‐of‐equilibrium species.

Hossain, Mohammad Mosharraf↗
DOE OSTI2020

Directional Bonding in Decaniobate Inorganic Frameworks

Abstract Metal–oxo clusters offer an opportunity to assemble inorganic and metal–organic frameworks (MOFs) by a controlled building‐block approach, which led to the revolutionary discoveries of zeolites and MOFs. Polyoxometalate clusters are soluble in water, but more challenging to link into frameworks; the inert oxo‐caps that provide solubility are resistant to replacement or further connectivity. We demonstrate how the unique directional bonding and varying basicity of the decaniobate ([Nb 10 ]) oxo‐caps can be exploited to build 1D, 2D, and 3D inorganic frameworks. In nine structures, A + (A=Li, Na, K, Rb and Cs), AE 2+ (AE=Ca, Sr, Ba) and Mn 2+ demonstrate that the dimensionality of the obtained material is controlled by cation charge and size. Increased cation charge decreases selectivity for oxo‐site bonding, leading to higher dimensional linking. Larger cation radii also decreases bonding selectivity, yielding higher dimensional materials. Ion‐exchange studies of the A + ‐Nb 10 family shows exclusive selectivity for Cs + over other alkalis, which is important for radioactive Cs removal and sequestration.

Martin, Nicolas P.↗
DOE OSTI2023

Elastic Moduli: a Tool for Understanding Chemical Bonding and Thermal Transport in Thermoelectric Materials

Abstract The elastic behavior of a material can be a powerful tool to decipher thermal transport. In thermoelectrics, measuring the elastic moduli—directly tied to sound velocity—is critical to understand trends in lattice thermal conductivity, as well as study bond anharmonicity and phase transitions, given the sensitivity of elastic moduli to the chemical bonding. In this review, we introduce the basics of elasticity and explain the origin of high‐temperature lattice softening from a bonding perspective. We then review elasticity data throughout classes of thermoelectrics, and explore trends in sound velocity, anharmonicity, and thermal conductivity. We reveal how experimental sound velocities can improve the accuracy of common thermal conductivity models and present a critical discussion of Grüneisen parameter estimates from elastic moduli. Readers will be equipped with tools to leverage elasticity measurements or calculations to accurately interpret thermal transport trends.

Isotta, Eleonora↗
DOE OSTI2025

Ligand‐Directed Actinide Oxo‐Bond Manipulation in Actinyl Thiacalix[4]arene Complexes

Abstract Understanding the chemistry of the inert actinide oxo bond in actinyl ions AnO 2 2+ is important for controlling actinide behavior in the environment, during separations, and in nuclear waste (An=U, Np, Pu). The thioether calixarene TC4A (4‐ tert ‐butyltetrathiacalix[4]arene) binds equatorially to the actinyl cation forming a conical pocket that differentiates the two trans‐ oxo groups. The ‘ate’ complexes, [A] 2 [UO 2 (TC4A)] (A=[Li(DME) 2 ], HNEt 3 ) and [HNEt 3 ] 2 [AnO 2 (TC4A)] (An=U, Np, Pu), enable selective oxo chemistry. Silylation of the U VI oxo groups by bis(trimethylsilyl)pyrazine occurs first at only the unencapsulated exo oxo and only one silylation is needed to enable migration of the endo oxo out of the cone, whereupon a second silylation affords the stable U IV cis‐ bis(siloxide) [A] 2 [U(OSiMe 3 ) 2 (TC4A)]. Calculations confirm that only one silylation event is needed to initiate oxo rearrangement, and that the putative cis dioxo isomer of [UO 2 (TC4A)] 2− would be stable if it could be accessed synthetically, at only 23 kcal.mol −1 in energy above the classical trans dioxo. Calculations for the transuranic cis [AnO 2 (TC4A)] 2− (An=Np, Pu) are at higher energies, 30–35 kcal.mol −1 , retaining the U complexes as the more obvious target for a cis ‐dioxo actinyl ion. The aryloxide (OAr) groups of the macrocycle are essential in stabilizing this as‐yet unseen uranyl geometry as further bonding in the TC4A U‐O Ar groups stabilizes the U=O ‘yl’ bonds, explaining the stability of the putative cis [UO 2 (TC4A)] 2− in this ligand framework.

Pyrch, Mikaela M. [College of Chemistry University↗
DOE OSTI2025

Late-Stage Oxidation of C( sp 3 )─H Bonds with High Efficiency and Alkyl Group Dihydroxylation of Complex Molecules

Here, the late-stage oxidation of C(sp 3 )─H bonds is highly valuable for modulating the solubility and binding of bioactive compounds and for diversification of complex molecules. Undirected methods for C(sp 3 )─H oxidation are valuable for the installation of hydroxyl groups at sites remote from other functional groups present in the molecule, but existing catalysts are limited by low turnover numbers and lengthy ligand syntheses. Perfluorinated ruthenium porphyrins are highly active catalysts for the oxidation of alkyl C─H bonds, but the scope of the transformation with complex molecules under conditions of limiting substrate has not been investigated. We report that carbonylruthenium(II) tetrakis(pentafluorophenyl)porphyrin [Ru(TPFPP)(CO)] catalyzes the selective oxidation of tertiary C(sp 3 )─H bonds in a broad range of complex natural products and drugs, with turnover numbers as high as 1000, and the tolerance of the reaction to various functional groups was rapidly assessed by performing a model reaction in the presence of additives. We show how the combination of this undirected C(sp 3 )─H oxidation and a directed C(sp 3 )─H silylation and oxidation provides rapid access to highly oxidized, 1,2-diol derivatives of natural products by a formal dihydroxylation of an alkyl group.

Alcohols↗
DOE OSTI2017

A Metal–Organic Framework with Exceptional Activity for C−H Bond Amination

Abstract The development of catalysts capable of fast, robust C−H bond amination under mild conditions is an unrealized goal despite substantial progress in the field of C−H activation in recent years. A Mn‐based metal–organic framework (CPF‐5) is described that promotes the direct amination of C−H bonds with exceptional activity. CPF‐5 is capable of functionalizing C−H bonds in an intermolecular fashion with unrivaled catalytic stability producing >10 5 turnovers.

Wang, Le↗
DOE OSTI2025

Ligand‐Directed Actinide Oxo‐Bond Manipulation in Actinyl Thiacalix[4]arene Complexes

Understanding the chemistry of the inert actinide oxo bond in actinyl ions AnO2 2+ is important for controlling actinide behavior in the environment, during separations, and in nuclear waste (An=U, Np, Pu). The thioether calixarene TC4A (4-tert-butyltetrathiacalix[4]arene) binds equatorially to the actinyl cation forming a conical pocket that differentiates the two trans-oxo groups. The 'ate' complexes, [A]2[UO2(TC4A)] (A=[Li(DME)2], HNEt3) and [HNEt3]2[AnO2(TC4A)] (An=U, Np, Pu), enable selective oxo chemistry. Silylation of the UVI oxo groups by bis(trimethylsilyl)pyrazine occurs first at only the unencapsulated exo oxo and only one silylation is needed to enable migration of the endo oxo out of the cone, whereupon a second silylation affords the stable UIV cis-bis(siloxide) [A]2[U(OSiMe3)2(TC4A)]. Calculations confirm that only one silylation event is needed to initiate oxo rearrangement, and that the putative cis dioxo isomer of [UO2(TC4A)]2- would be stable if it could be accessed synthetically, at only 23 kcal.mol-1 in energy above the classical trans dioxo. Calculations for the transuranic cis[AnO2(TC4A)]2- (An=Np, Pu) are at higher energies, 30-35 kcal.mol-1, retaining the U complexes as the more obvious target for a cis-dioxo actinyl ion. The aryloxide (OAr) groups of the macrocycle are essential in stabilizing this as-yet unseen uranyl geometry as further bonding in the TC4A U-OAr groups stabilizes the U=O 'yl' bonds, explaining the stability of the putative cis[UO2(TC4A)]2- in this ligand framework.

Pyrch, Mikaela M↗
DOE OSTI2017

From Coordination Cages to a Stable Crystalline Porous Hydrogen-Bonded Framework

A stable framework has been constructed through multiple charge-assisted H-bonds between cationic coordination cages and chloride ions. The framework maintained its original structure upon desolvation, which has been established by single-crystal structure analysis. This is the first fully characterized stable porous framework based on coordination cages after desolvation, with a moderately high Brunauer–Emmett–Teller (BET) surface area of 1201 m2 g-1. This work will not only give a light to construct stable porous frameworks based on coordination cages and thus broaden their applications, but will also provide a new avenue to the assembly of other porous materials such as porous organic cages and hydrogen-bonded organic frameworks (HOFs) through non covalent bonds.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

The Surprising Importance of Peptide Bond Contacts in Drug–Protein Interactions

The study of noncovalent interactions, notably including drug–protein binding, relies heavily on the language of localized functional group contacts: hydrogen bonding, π–π interactions, CH–π contacts, halogen bonding, etc. Applying the state-of-the-art functional group symmetry-adapted perturbation theory (F-SAPT) to an important question of chloro versus methyl aryl substitution in factor Xa inhibitor drugs, we find that a localized contact model provides an incorrect picture for the origin of the enhancement of chloro-containing ligands. Instead, the enhancement is found to originate from many intermediate-range contacts distributed throughout the binding pocket, particularly including the peptide bonds in the protein backbone. The contributions from these contacts are primarily electrostatic in nature, but require ab initio computations involving nearly the full drug–protein pocket system to be accurately quantified.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗