Observations on Macroscopic Surface Modification and Oxidation of Tungsten and Tungsten Carbide in Laser Focus in Air
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36 MATERIALS SCIENCE↗
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Surface Modification of Ti-6Al-4V for Dust Adhesion Mitigation in Lunar Exploration
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Lunar dust, Harsh environment, Adhesion mitigation↗
Analysis of the Effect of Surface Modification on Polyimide Composites Coated with Erosion Resistant Materials
The aim of this research is to enhance performance of composite coatings through modification of graphite-reinforced polyimide composite surfaces prior to metal bond coat/ hard topcoat application for use in the erosive and/or oxidative environments of advanced engines. Graphite reinforced polyimide composites, PMR-15 and PMR-II-50, formed by sheet molding and pre-pregging will be surface treated, overlaid with a bond coat and then coated with WC-Co. The surface treatment will include cleaning, RF plasma or ultraviolet light- ozone etching, and deposition of SiO(x) groups. These surface treatments will be studied in order to investigate and improve adhesion and oxidation resistance. The following panels were provided by NASA-Glenn Research Center(NASA-GRC): Eight compression molded PMR-II-50; 6 x 6 x 0.125 in. Two vacuum-bagged PMR-II-50; 12 x 12 x 0.125 in. Eight compression molded PMR-15; 6 x 6 x 0.125 in. One vacuum-bagged PMR-15; 12 x 12 x 0.125 in. All panels were made using a 12 x 12 in. T650-35 8HS (3K-tow) graphite fabric. A diamond-wafering blade, with deionized water as a cutting fluid, was used to cut PMR-II-50 and PMR-15 panels into 1 x 1 in. pieces for surface tests. The panel edges exhibiting delamination were used for the preliminary surface preparation tests as these would be unsuitable for strength and erosion testing. PMR-15 neat resin samples were also provided by NASA GRC. Surface profiles of the as-received samples were determined using a Dektak III Surface profile measuring system. Two samples of compression molded PMR-II-50 and PMR-15, vacuum-bagged PMR-II-50 and PMR-15 were randomly chosen for surface profile measurement according to ANSI/ASME B46.1. Prior to each measurement, the samples were blasted with compressed air to remove any artifacts. Five 10 mm-long scans were made on each sample. The short and long wavelength cutoff filter values were set at 100 and 1000 m, diamond stylus radius was 12.5 microns. Table 1 is a summary of the arithmetic average roughness (Ra) and waviness (Wa) for the composite surfaces.
Ndalama, Tchinga↗
An improved oxygen reduction reaction activity and CO 2 -tolerance of La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ achieved by a surface modification with barium cobaltite coatings
Solid oxide fuel cells (SOFCs) cathode often suffers from the poisoning effect of the contaminants commonly encountered in air such as CO 2 . Here we report an effective approach to enhancing the activity and CO 2 tolerance of the state-of-the-art La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ (LSCF) cathode enabled by a coating of BaCoO 3-δ (BCO), as verified by the electrochemical testings, Raman analyses, and density functional theory calculations. When surface modified with a thin-film BCO coating, LSCF displays a much enhanced ORR activity and an improved durability against CO 2 . For example, anode supported SOFCs with the LSCF cathode coated with BCO coatings show a remarkable peak power density (Pmax) of 0.41 Wcm -2 and a significantly reduced degradation rate in current density of ~0.08% h -1 at 0.8 V and 700 °C for a period of 300 hs when humidified H2 (with 3 vol%H2O) was used as fuel and air with 8 vol% CO 2 as oxidant. The demonstrated performance is improved when compared with those of the cells with a blank LSCF electrode (a Pmax of ~0.36 Wcm -2 and a degradation rate of ~0.15% h -1 ) under the same conditions. Furthermore, the adsorption energy calculations suggests that BCO coating makes CO 2 adsorption much weaker than LSCF (-0.54 eV versus -1.07 eV).
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
Unravelling the Influence of Surface Modification on the Ultimate Performance of Carbon Fiber/Epoxy Composites
Not Available
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Plasma-assisted surface modification of biopolymers
The interaction of non-thermal plasmas with surfaces is an important problem of interest in various applications. This work focuses on two main aspects of the problem - simulation and experiments. The development of a low-temperature plasma modeling is described along with experiments focusing on the interaction of a low-temperature plasma with liquid water. The simulation framework is capable of handling arbitrary geometries, chemistry and a fully-coupled boundary condition for plasma-dielectric interface. Representative examples for the verification and validation of the framework are provided. The experimental work deals with the study of low-temperature plasmas with water with the nitrate injection rate compared for three different configurations.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
Wind-tunnel Investigation of Effects of Rear Upper Surface Modification on a NASA Supercritical Airfoil
Wind tunnel tests were conducted at Mach numbers from 0.60 to 0.81 to examine the effects on supercritical airfoil of modifying the rear upper surface to reduce the magnitude of an intermediate off design second velocity peak. The modification was accomplished by increasing the upper surface curvature around the 50 percent chord station and reducing the curvature over approximately the rearmost 30 percent of the airfoil while maintaining the same trailing edge thickness.
Harris, C. D.↗
Noncovalent Surface Modification of Metal–Organic Frameworks: Unscrambling Adsorption Properties via Isothermal Titration Calorimetry
Despite the importance of noncovalent interactions in the utilization of metal–organic frameworks (MOFs), using these interactions to functionalize MOFs has rarely been explored. The ease of functionalization and potential for surface-selective functionalization makes modification via noncovalent interactions promising for the creation of porous photocatalytic assemblies. Here, using isothermal titration calorimetry, photoluminescence measurements, and desorption experiments, we have explored the nature and magnitude of the interactions of [Ru(bpy) 2 (bpy-R)] 2+ -functionalized dyes with the surface of MIL-96, where R = C 3 , C 8 , C 12 , and C 18 alkyl chains of either straight-chain or cyclic conformations. The orientation of the dyes appears to be flat against the surface with respect to the long alkyl chains, and the surface concentration approaches a monolayer at high initial concentrations of dye. Strangely, the dodecyl-functionalized dye, despite having a smaller interaction energy and larger footprint than either octyl-functionalized dye, achieves the highest maximum surface concentration. Based on photoluminescence spectra, desorption experiments, and ITC data, we believe this is due to the core of the dye being lifted from the surface as the chain length increases. Our understanding of these interactions is important for further utilization of this method for the functionalization of the internal and external surface areas of MOFs.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Upper-surface modifications for C sub l max improvement of selected NASA 6-series airfoils
The thickness of the upper surface of 64 airfoils was increased from the leading edge to the position of maximum thickness. The modifications were generated using a numerical optimization routine coupled with an aerodynamic analysis code. The type of modification presented can be used for aircraft design or for the retrofit of current aircraft to improve the stall characteristics and climb performance. The coordinates of the modified airfoils are presented with plots of the forward 45% of the profiles and pressure distributions for both the modified and unmodified sections at an angle of attack of 14 degrees.
Szelazek, C. A.↗
Boosting CO 2 Electrochemical Reduction with Atomically Precise Surface Modification on Gold Nanoclusters
Thiolate-protected gold nanoclusters (NCs) are promising catalytic materials for the electrochemical CO 2 reduction reaction (CO 2 RR). In this work an atomic level modification of a Au 23 NC is made by substituting two surface Au atoms with two Cd atoms, and it enhances the CO 2 RR selectivity to 90–95 % at the applied potential between -0.5 to -0.9 V, which is doubled compared to that of the undoped Au 23 . Additionally, the Cd-doped Au 19 Cd 2 exhibits the highest CO 2 RR activity (2200 mA mg -1 at -1.0 V vs. RHE) among the reported NCs. This synergetic effect between Au and Cd is remarkable. Density-functional theory calculations reveal that the exposure of a sulfur active site upon partial ligand removal provides an energetically feasible CO 2 RR pathway. The thermodynamic energy barrier for CO formation is 0.74 eV lower on Au 19 Cd 2 than on Au 23 . Here these results reveal that Cd doping can boost the CO 2 RR performance of Au NCs by modifying the surface geometry and electronic structure, which further changes the intermediate binding energy. This work offers insights into the surface doping mechanism of the CO 2 RR and bimetallic synergism.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Improved interfacial li-ion transport in composite polymer electrolytes via surface modification of LLZO
Composite polymer electrolytes that incorporate ceramic fillers in a polymer matrix offer mechanical strength and flexibility as solid electrolytes for lithium metal batteries. However, fast Li + transport between polymer and Li + -conductive filler phases is not a simple achievement due to high barriers for Li + exchange across the interphase. This study demonstrates how modification of Li 7 La 3 Zr 2 O 12 (LLZO) nanofiller surfaces with silane chemistries influences Li + transport at local and global electrolyte scales. Anhydrous reactions covalently link amine-functionalized silanes [(3-aminopropyl)triethoxysilane (APTES)] to LLZO nanoparticles, which protects LLZO in air. APTES functionalization lowers the poly (ethylene oxide) (PEO)-LLZO interphase resistance to half that of unmodified LLZO and increases effective Li + transference number, while insulating Al 2 O 3 completely blocks ion exchange and lowers transference number and conductivity in PEO-lithium bis(trifluoromethanesulfonyl)imide (LiTFSI)-LLZO composites. Modeling an inner resistive interphase between LLZO and PEO surrounded by an outer conductive interphase explains non-linear conductivity trends. Solid-state 7 Li & 6 Li nuclear magnetic resonance shows Li + only exchanges between PEO-LiTFSI and some LLZO interphase, with no appreciable Li + transport through bulk LLZO. Surface functionalization is a promising path toward lowering the polymer-ceramic interphase resistance. This work demonstrates that local changes in Li + transport affect macroscopic performance, highlighting the intricate relationships between all interfaces in inherently heterogeneous composite polymer electrolytes.
25 ENERGY STORAGE↗
The effect of surface modifications on the burning rate of a composite solid propellant.
Temperature at which predecomposition or decomposition of ammonium perchlorate occurs, changed by perchlorate surface treatment and reflected in burning rate of propellant containing perchlorate
COMPOSITE PROPELLANT↗
Surface modification of Venus as inferred from Magellan observations of plains
Magellan radar and altimetry data are analyzed to understand the extent to which surface processes, such as impact crater ejecta emplacement, aeolian processes, and weathering, have modified Venusian plains. The analysis focuses on three areas: (1) lava flows of different relative ages in Sedna Planitia to determine the degradation history of Venusian volcanic surfaces; (2) the 65-km-diameter impact crater Stuart to evaluate the effects of ejecta emplacement on plains surfaces; and (3) elevated plains in western Ovda Regio to explore the nature and rate of production of highly reflective surfaces that dominate terrains that are greater than 6054 km in radius.
Arvidson, Raymond E.↗
Hybrid Doping Strategy with High‐Entropy Cu/Fe Surface Modification and Zr Bulk Incorporation for Ni‐Rich Cathodes
A hybrid doping strategy combining Zr 4+ bulk doping with high-entropy Cu 2+ /Fe 3+ surface doping is developed to enhance the structural and interfacial stability of Ni-rich layered oxide cathodes. Cu and Fe are selectively introduced at the particle surface via a surface-selective ion-exchange process, forming a ≈15 nm Fe-rich layer while preserving the layered framework. Compared to the pristine cathode, the hybrid sample exhibits significantly improved electrochemical performance in both half-cell and full-cell configurations. In half-cells, the hybrid retains 88.5% and 90.2% after 100 cycles at 1C under 4.6 and 4.5 V, respectively. During high-voltage full-cell cycling, the hybrid cathode maintains over 80% capacity retention, whereas the pristine counterpart retains less than 10% under identical conditions over the same cycling period. XPS, EELS, and DEMS analyses confirm improved oxygen retention, suppressed gas evolution, and stable surface chemistry, while DFT calculations indicate enhanced Me–O bonding in the selected Fe 0.75 Cu 0.25 (Mn 1/16 Co 2/16 Ni 13/16 )O 2 surface composition, which is identified through DFT-calculated mixing energy reaching a minimum at this ratio, indicating the most thermodynamically favorable configuration. In conclusion, these results demonstrate the effectiveness of this hybrid doping strategy in mitigating coupled degradation pathways in Ni-rich cathodes.
15 GEOTHERMAL ENERGY↗
Ion beam surface modification
The essential details of a study on the practical applications and mechanisms of polymer sputtering via Argon ion impact are summarized. The potential to modify the properties of polymer surfaces to improve their adherence, durability, biocompatibility, or other desirable properties by ion beam sputtering was emphasized. Ion beam milling can be of benefit as an analytical tool to obtain composition versus depth information. Ion impact from a directed ion gun source specifically etches polymer structures according to their morphologies, therefore this technique may be useful to study unknown or new morphological features. Factors addressed were related to: (1) the texture that arises on a polymer target after ion impact; (2) the chemistry of the top surface after ion impact; (3) the chemistry of sputtered films of polymeric material deposited on substrates placed adjacent to targets during ion impact; and (4) practical properties of textured polymer targets, specifically the wettability and adhesive bonding properties.
Dwight, D. W.↗
Chemical Schemes for Surface Modification of Icy Satellites: A Road Map
The icy Galilean satellites of Jupiter are subject to magnetospheric plasma ion bombardment, which induces chemical changes within the ice. The possible detection of CO2 on the surface of Ganymede by the Galileo spacecraft makes for a more complicated chemistry and increases the number of chemical compounds that may then be present. We outline chemical schemes for the irradiation of pure and mixed ices H2O/CO2 and suggest species which observers may detect on Europa, Ganymede, and Callisto, such as C3O2, H2CO3, H2O2, CO3, HO2, CO, H2CO, CH2CO, as well as K2O, KOH, and SO3, from plasma implantation. Column abundances of compounds in the ice are calculated using a specified energy input and G values (yield per 100 eV).
Delitsky, Mona L.↗
Chemical Schemes for Surface Modification of Icy Satellites: A Road Map
The icy Galilean Satellites of Jupiter are subject to magnetospheric plasma ion bombardment which induces chemical changes within the ice. The possible detection of CO2 on the surface of Ganymede by the Galileo spacecraft makes for a more complicatred chemistry and increases the number of chemical compounds that may then be present.
Galileo↗
Surface modification of Monel K-500 as a means of reducing friction and wear in high-pressure oxygen
A study is conducted of the tribological characteristics of Monel K-500 during rubbing in a high pressure oxygen atmosphere, upon surface treatment by ion-implanted oxygen, chromium, lead, and silver, as well as electrolyzed chromium and an electroless nickel/SiC composite. The electrolyzed chromium dramatically increased total sample wear, while other surface treatments affected sample wear only moderately. Although the ion-implant treatments reduced the average coefficient of friction at low contact pressure, higher contact pressures eliminated this improvement.
Gunaji, Mohan↗