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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 991 records · Page 55
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Solvothermal synthesis of a new 3-D mixed-metal sulfide framework, (H{sub 1.33}tren)[In{sub 2.67}Sb{sub 1.33}S{sub 8}]·tren

A new indium(III) antimony(V) sulfide, (H{sub 1.33}tren)[In{sub 2.67}Sb{sub 1.33}S{sub 8}]·tren, has been prepared solvothermally at 433 K. The compound crystallises in the tetragonal space group I-42d (lattice parameters, a=12.6248(5) and c=19.4387(18) Å at 150 K) and contains adamantane-like T2 supertetrahedral units comprised of corner-sharing InS{sub 4}{sup 5−} and SbS{sub 4}{sup 3−} tetrahedra. The adamantane-like units are then linked through sulfur vertices to generate an open, 3-D framework structure containing large pores in which neutral, protonated tren (tris(2-aminoethylene)amine) molecules reside. The presence of the organic components was confirmed by solid-state {sup 13}C NMR (10 kHz), combustion and thermogravimetric analysis. The band gap, obtained from UV–vis diffuse reflectance measurements, is 2.7(2) eV. Stirring with either water or alkali-metal salt solution leads to removal of the neutral tren molecules and an ~9% reduction in unit-cell volume on formation of (H{sub 1.33}tren)[In{sub 2.67}Sb{sub 1.33}S{sub 8}]·(H{sub 2}O){sub 4}. - Graphical abstract: Linking of In(III)-Sb(V)-S adamantane units to form a 3-D open framework. - Highlights: • Preparation and structural characterisation of a new mixed-metal thiometallate. • The first mixed In(III)/Sb(V) supertetrahedron. • Optical band gap of 2.7(2) eV. • Soaking in aqueous alkali-metal solutions leads to removal of ca. 50% of the organic content.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Conditions for the formation of pure birnessite during the oxidation of Mn(II) cations in aqueous alkaline medium

Birnessite was synthetized through redox reaction by mixing MnO{sub 4}{sup -}, Mn{sup 2+} and OH{sup -} solutions. The Mn(VII): Mn(II) ratio of 0.33 was chosen and three methods were used consisting in a quick mixing under vigorous stirring of two of the three reagents and then on the dropwise addition of the third one. The obtained solids were characterized by XRD, FTIR and XPS spectroscopies. Their average oxidation states were determined from ICP and CEC measurements while their surface properties were investigated by XPS. This study provides an increased understanding of the importance of dissolved oxygen in the formation of birnessite and hausmannite and shows the ways to obtain pure birnessite. The role of counter-ion ie. Na{sup +} or K{sup +} was also examined. - Graphical abstract: Pathways of birnessite formation. - Highlights: • Pure birnessite is prepared through a redox reaction. • Hausmannite formation is prevented by controlling dissolved O2. • The employed counterion influences the purity of birnessite. • Initial Mn(OH){sub 2} is oxidized by both MnO{sub 4}{sup -} and dissolved O{sub 2}.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Microstructural evolution in an ultra-fine YAl{sub 2p} reinforced Mg–14Li–3Al composite during warm-rolling

The YAl{sub 2p}/MgLiAl composite prepared by stir casting was initially forged and then rolled at 200 °C to different thicknesses. The microstructural evolution in the composite during warm rolling was investigated by using transmission electron microscope (TEM). It is found that increasing rolling reduction is conducive to the uniform distribution and refinement of the YAl{sub 2} particles. The rolling deformation promoted the precipitation of an α phase, and the α precipitate is semi-coherent to the matrix with an orientation relationship to the β matrix as: (0002){sub α}‖(110){sub β}. In addition, many nano-sized YAl particles with a cubic shape were found in the matrix of the composite with a high rolling reduction due to the diffusion of Y from YAl{sub 2} to the matrix, which reacted with the Al in the matrix during warm rolling. - Highlights: • The reinforcement YAl{sub 2} particles were distributed more uniformly in the matrix and refined with increasing rolling reduction. • The rolling deformation promoted and refined the precipitation of an α phase with increasing rolling reduction. • Many nano-sized YAl phases were produced and distributed in the matrix of the composite at a high rolling reduction.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Grain structure, texture and mechanical property evolution of automotive aluminium sheet during high power ultrasonic welding

High power ultrasonic spot welding (HPUSW) is a joining technique which is performed within less than a second and provides a more energy-efficient alternative to friction stir spot welding (FSSW), which is considered a longer cycle manufacturing process for joining automotive alloys. To date, only a few reports exist on the deformation mechanisms that take place during high power ultrasonic spot welding. In this work, dynamic recrystallization and grain growth were examined using electron backscatter diffraction (EBSD). HPUSW causes extensive deformation within the weld zone where the temperature increases to 440 °C. An ultra-fine grain structure was observed in a thin band of flat weld interface within a short welding time of 0.10 s. With increasing welding time the interface was displaced and ‘folds’ or ‘crests’ appeared together with shear bands. The weld interface progressively changed from flat to sinusoidal and eventually to a convoluted wave-like pattern when the tool fully penetrated the workpiece, having a wavelength of ~ 1 mm after 0.40 s. Finally, the microstructure and texture varied significantly depending on the location within the weld. Although the texture near the weld interface was relatively weak, a shift was observed with increasing welding time from an initially Cube-dominated texture to one where the typical β-fibre Brass component prevailed. - Highlights: •Lap shear strength of ~2.9 kN was achieved in 0.30 sec welding time. •Temperature approached 440 °C along the weld centreline for the highest welding time. •The texture near the teeth was dominated by Brass, P and S components at optimum condition. •The weld interface showed typical β-fibre deformation texture at optimum condition.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Friction consolidation of gas-atomized Fe−Si powders for soft magnetic applications

Soft magnetic materials are often limited in scalability due to conventional processes that do not retain beneficial microstructures, and their associated physical properties, during densification. In this work, friction consolidation (FC) has been studied to fabricate Fe−Si soft magnetic materials from gas-atomized powder precursors. Fe−Si powder is consolidated using variable pressure and tool rotation speed in an effort to evaluate this unique densification approach for potential improvements in magnetic properties. FC, due to the high shear deformation involved, is shown to result in uniform gradual grain structure refinement across the consolidated workpiece from the center nearest the tool to the edge. Magnetic properties along different orientations indicate little, if any, textural orientation in the refined grain structure. The effect of annealing on the magnetic properties is evaluated and shown to decrease coercivity. FC processing was able to retain the magnetization of the original gas-atomized powders but further process optimization is needed to reach the optimal coercivity for the soft magnetic materials applications. - Highlights: •Friction stir processing was utilized to consolidate Fe−Si soft magnetic powders. •The resultant microstructure and magnetic properties were correlated to the processing conditions. •Friction consolidation refined the grain size of the materials by ~ 40%. •Annealing successfully reduced the coercivity induced by the stress during processing. •The results shine light on the possible scaling up of nanostructured materials.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Direct hydrothermal synthesis of hydroxyapatite/alumina nanocomposite

Hydrothermal synthesis offers numerous advantages such as: control over product homogeneity, nucleation, growth and aging. This leads to the control of particle aggregation, size uniformity and morphology over conventional and non-conventional ceramic synthesis methods. In the present work, a novel procedure for the direct synthesis of Hydroxyapatite (HAp)/alumina nanocomposite in a hydrothermal vessel with continuous stirring was investigated, where the effects of different concentration of aluminium nitrate were also studied. The optimized concentration of starting material for the characteristic formation of HAp/alumina composite (hexagonal HAp and monoclinic alumina phases) was determined by X-ray diffraction (XRD) study. The size distribution of HAp/alumina composite was found as 100 nm by electron microscopy and EDAX revealed that the concentration of alumina in the HA4 was ~ 10%, which is more suitable for biomedical implant. Further, the cytotoxicity study against MG 63 cells showed that HA4 was biocompatible even at higher concentration (200 μg/ml). Hence, the direct synthesis of HAp/alumina composite without the formation of any intermediate like calcium aluminate could be used as a novel approach to prepare HAp based biomedical implants.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Novel preparation of Al-5%Cu / BN and Si3N4 composites with analyzing microstructure, thermal and mechanical properties

Highlights: • The novel MMCs Al5Cu-Si{sub 3}N{sub 4}/BN successfully produced by squeeze casting techniques • Squeeze casting technique improves the wettability between the matrix and nitrides. • XRD analysis showing the presence of new AlN and AlB{sub 2} phases • The hardness curves of the MMCs exhibited the increasing trend till reaching peak. • BN reinforcements significantly accelerate precipitation behavior of Al-5%Cu alloy. - Abstract: The purpose of this research is to develop and characterize composites of Al-5%Cu alloy reinforced by silicon and boron nitride (Si{sub 3}N{sub 4}, BN). The developing of this type of composites gives a new trend of metal matrix composite synthesizing, especially in the case of boron nitride. The stir cast composites showed large areas of porosity and agglomeration. On the other hand, the squeezed cast composites exhibited a fairly uniform particles distribution throughout the matrix alloy. The microstructure and XRD results of the composites confirmed a reaction occurred at the interface between the particles and alloy. AlN and AlB{sub 2} phases were identified in Al5%Cu-Si{sub 3}N{sub 4} and Al5%Cu-BN composites respectively. The ageing results showed that the time to reach peak hardness decreased with addition of the particles. Also, the ageing kinetics was significantly accelerated due to the presence of BN particulates. The coefficient of thermal expansion (CTE) results of the matrix alloy and its composites were practically and theoretically determined. Difference between experimental and calculated values of CTE was less than 8%. Increasing the concentration of Si{sub 3}N{sub 4} increased YS from 215 MPa in the matrix alloy to 285 MPa in the Al-5%Cu-7%Si{sub 3}N{sub 4} composites at a testing temperature of 20 °C.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Preparation and characterization of the Al-Cu-Mg-Si-Mn composites reinforced by different surface modified SiCp

Highlights: • The Ti-coated SiC{sub p} exhibited more uniformly distribution in composites than that of pre-oxidized SiC{sub p}. • Ti-coated SiC{sub p} obtained better SiC{sub p}-Al interface bonding than that of pre-oxidized SiC{sub p}. • The composites reinforced by Ti-coated SiC{sub p} exhibited better tensile properties than that reinforced by pre-oxidized SiC{sub p}. - Abstract: In this paper, the 4 vol% SiC{sub p}/Al-Cu-Mg-Si-Mn composites were prepared by method of stirring casting. The effects of SiC{sub p} surface modifications (oxidization and Ti-coating) and particle sizes (5 μm, 10 μm and 15 μm) on the microstructure and tensile properties of the composites were analyzed. The effects of SiC{sub p} sizes on the distribution of SiC{sub p} in the pre-oxidized SiC{sub p}/Al-Cu-Mg-Si-Mn composites were larger than those in Ti-coated SiC{sub p}/Al-Cu-Mg-Si-Mn composites. The Al-Cu-Mg-Si-Mn composites reinforced with Ti-coated SiC{sub p} exhibited more uniform SiC{sub p} distributions and higher tensile mechanical properties than those reinforced with the pre-oxidized SiC{sub p}. When the SiC{sub p} size was 15 μm, the Ti-coated SiC{sub p}/Al-Cu-Mg-Si-Mn composite showed the best yield strength (σ{sub 0.2}), ultimate tensile strength (σ{sub UTS}) and fracture strain (ε{sub f}) of 410 MPa, 548 MPa and 7.6% with the increase of 10.2%, 2.6% and 5.6% than that of reinforced by pre-oxidized SiC{sub p}. The more uniformly dispersed particles and better tensile properties of the Ti-coated SiC{sub p}/Al-Cu-Mg-Si-Mn composites could be attributed to the better wetting between Ti-coated SiC{sub p} and molten Al.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Fabrication of localised aluminium foam by a novel polymeric blowing agent

Highlights: • Polymeric blowing agent used to synthesize metallic foam for first time. • Localised region of a metallic part is foamed. • A novel semisolid route is used to control the pore size of the foams. • Heat-treatable foam with controllable absorption energy is obtained. - Abstract: Closed cell aluminium foams are highly pursued, due to their unique combination of properties. However, the current applicability of the aluminium foams is limited due to issues like high costs, density-gradient and brittleness of the cell walls, which are either related to use of metallic hydride as blowing agent or liquid-state processing. To address these issues, this study presents a first attempt to use polymer as a blowing agent to foam an aluminium alloy. A polymer is Poly (methyl hydro siloxane) was dispersed into an Al2024 sheet of 6 mm by Friction Stir Processing, in a localised region. This processed sample was pyrolysed at temperatures between solidus and liquidus (500–640 °C) of the alloy and at various durations (5–60 min) to foam the localised precursor. The density of resulting foams was measured by the Archemidies method and the resulting pore structures were characterised by Scanning Electron Microscopy (SEM) and micro X-ray Computed Tomography (CT). The results show that by as pyrolysis temperature increases relative density reaches a minimum of 0.65 at 560 °C. Beyond 590 °C, relative density increased from the optimum due to escape of foaming gasses. With increasing pyrolysis temperature, the pore size increased from few microns to several hundred microns. Further, quasi-static compression test was done on as processed, solutionized and aged foams. Due to increased strain hardening in aged samples energy absorbed during compression increased by 80% in the plateau region. Hence, polymeric a blowing agent can be used to synthesize heat-treatable foams with controllable absorption energy.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Metallurgical Joining of immiscible system: Pure Mg and Pure Fe

Understanding the metallurgical joinability of pure Mg and pure Fe and their interfacial microstructure lays the foundation for deciphering the complicated mechanism of joining various magnesium alloys and steels in applications. We first produced a successful metallurgical joint between pure Mg and pure Fe using the friction stir assisted scribe technique. Through detailed characterization, we found that the two immiscible metals are bonded by a critical interfacial oxide layer that spans only ~40 ± 10 nm. We present the first direct experimental evidence of the presence of a Mg/Fe oxide rich interfacial layer using high-resolution electron microscopy and discuss the contribution of oxide formation toward a successful joining mechanism.

Das, Hrishikesh↗
DOE OSTI2025

Additive manufacturing of metal matrix composites

Although Metal matrix composites (MMCs) are superior to most sought-after metallic alloys, their challenging fabricability has limited their widespread use in bulk-form applications. Among the many advanced fabrication techniques, Additive Manufacturing (AM), owing to its unique capabilities to produce near-net shapes, has drawn significant traction in the past two decades, especially for materials that are difficult to process using traditional methods. However, unlike pure metal/alloy systems, MMCs are highly sensitive to the processing conditions prevailing in AM techniques due to factors such as the high melting point of reinforcement particles and the potential for in-situ reactions. Therefore, it may be a while before metal matrix composites are commercially produced via AM. This review will discuss the current state-of-the-art design, fabricability, and performance of various additively manufactured MMCs. A particular focus will be on microstructural evolution and microstructure-property relationships. The most employed AM techniques, such as directed energy deposition, powder bed fusion, binder jetting, sheet lamination, and solid-state friction stir processing, are fundamentally different in terms of thermo-kinetics, forming the perspective for this review. A detailed comparison of microstructural evolution and process parameter optimization, including feedstock preparation methods and the role of machine learning and modeling among the different AM processes, is also presented. Finally, a critical evaluation of emerging AM technologies for MMCs is also provided, highlighting their potential advantages and challenges.

36 - MATERIALS SCIENCE↗
DOE OSTI2011

Synthesis, characterization and optical properties of sheet-like ZnO

Highlights: {yields} Sheet-like ZnO with regular hexagon shape was synthesized with a two-step method. {yields} Sheet-like ZnO predecessor was synthesized at low temperature in open system. {yields} The diameter and thickness of ZnO sheet can be controlled conveniently. {yields} This low-cost and environmentally benign approach is controllable and reproducible. {yields} Sheet-like ZnO may have potential application in optical and electrical devices. -- Abstract: Sheet-like ZnO with regular hexagon shape and uniform diameter has been successfully synthesized through a two-step method without any metal catalyst. First, the sheet-like ZnO precursor was synthesized in a weak alkaline carbamide environment with stirring in a constant temperature water-bath by the homogeneous precipitation method, then sheet-like ZnO was obtained by calcining at 600 {sup o}C for 2 h. The structures and optical properties of sheet-like ZnO have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), photoluminescence (PL) and UV-vis-NIR spectrophotometer. The results reveal that the product is highly crystalline with hexagonal wurtzite phase and has appearance of hexagon at (0 0 0 1) plane. The HRTEM images confirm that the individual sheet-like ZnO is single crystal. The PL spectrum exhibits a narrow ultraviolet emission at 397 nm and a broad visible emission centering at 502 nm. The band gap of sheet-like ZnO is about 3.15 eV.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Particle size effect of Ni-rich cathode materials on lithium ion battery performance

Graphical abstract: The preparation condition of Ni-rich cathode materials was investigated. When the retention time was short, a poor cathode performance was observed. For long retention time condition, cathode performance displayed a best result at pH 12. Highlights: Black-Right-Pointing-Pointer Ni-rich cathode materials (LiNi{sub 0.8}Co{sub 0.15}Al{sub 0.05}O{sub 2}) were prepared by co-precipitation method using separate addition of Al salt. Black-Right-Pointing-Pointer Particle size of Ni-rich cathode materials became larger with increase of retention time and solution pH. Black-Right-Pointing-Pointer Cathode performance was poor for low retention time. Black-Right-Pointing-Pointer Optimal pH for co-precipitation was 12. -- Abstract: Herein, Ni-rich cathode materials (LiNi{sub 0.8}Co{sub 0.15}Al{sub 0.05}O{sub 2}) in lithium ion batteries are prepared by a separate addition of Ni/Co salt and Al sol solution using a continuously stirred tank reactor. Retention time and solution pH were controlled in order to obtain high performance cathode material. Particle size increase was observed with a higher retention time of the reactants. Also, primary and secondary particles became smaller according to an increase of solution pH, which was probably due to a decrease of growth rate. From the cathode application, a high discharge capacity (175 mAh g{sup -1}), a high initial efficiency (90%) and a good cycleability were observed in the cathode material prepared under pH 12 condition, which was attributed to its well-developed layered property and the optimal particle size. However, rate capability was inversely proportional to the particle size, which was clarified by a decrease of charge-transfer resistance measured in the electrochemical impedance spectroscopy.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Zero-valent iron nanoparticles preparation

Graphical abstract: Zero-valent iron nanoparticles were synthesized by hydrogenating [Fe[N(Si(CH{sub 3}){sub 3}){sub 2}]{sub 2}] at room temperature and a pressure of 3 atm. The synthesized nanoparticles were spherical and had diameters less than 5 nm. Highlights: ► Zero-valent iron nanoparticles were synthesized by hydrogenating [Fe[N(Si(CH{sub 3}){sub 3}){sub 2}]{sub 2}]. ► The conditions of reaction were at room temperature and a pressure of 3 atm. ► The synthesized nanoparticles were spherical and had diameters less than 5 nm. -- Abstract: Zero-valent iron nanoparticles were synthesized by hydrogenating [Fe[N(Si(CH{sub 3}){sub 3}){sub 2}]{sub 2}] at room temperature and a pressure of 3 atm. To monitor the reaction, a stainless steel pressure reactor lined with PTFE and mechanically stirred was designed. This design allowed the extraction of samples at different times, minimizing the perturbation in the system. In this way, the shape and the diameter of the nanoparticles produced during the reaction were also monitored. The results showed the production of zero-valent iron nanoparticles that were approximately 5 nm in diameter arranged in agglomerates. The agglomerates grew to 900 nm when the reaction time increased up to 12 h; however, the diameter of the individual nanoparticles remained almost the same. During the reaction, some byproducts constituted by amino species acted as surfactants; therefore, no other surfactants were necessary.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2012

Room temperature synthesis and photocatalytic property of AgO/Ag{sub 2}Mo{sub 2}O{sub 7} heterojunction nanowires

Graphical abstract: The AgO nanoparticles are attached on the surface of the Ag{sub 2}Mo{sub 2}O{sub 7} nanowires to form a heterojunction structure. The AgO nanoparticles start embedding into the nanowires with increasing reaction temperature or time. Highlights: ► AgO/Ag{sub 2}Mo{sub 2}O{sub 7} heterojunction NWs were synthesized at room temperature for the first time. ► AgO particles embed into the Ag{sub 2}Mo{sub 2}O{sub 7} NWs with increase in reaction time and temperature. ► The heterojunction NWs display much better photocatalytic activity than the none-heterojunction NWs. ► The catalytic mechanism was proposed. -- Abstract: AgO/Ag{sub 2}Mo{sub 2}O{sub 7} heterojunction nanowires were synthesized at temperatures of 25 °C, 50 °C, 80 °C, and 110 °C, under magnetic stirring in solution reaction. The catalytic activity of AgO/Ag{sub 2}Mo{sub 2}O{sub 7} nanowires was evaluated by the degradation of Rhodmine B dye under the irradiation of the simulated sunlight. The synthesized samples were characterized by X-ray diffractometer, energy dispersive spectrometry, X-ray photoelectron spectrometer, scanning electron microscopy, and transmission electron microscopy. The results show that the AgO nanoparticles are attached on the surface of the Ag{sub 2}Mo{sub 2}O{sub 7} nanowires to form a heterojunction structure. The length of the nanowires is up to 10 μm and the size of the AgO nanoparticles is 10–20 nm. The length of nanowires increases with increasing reaction time and temperature while the AgO particles are gradually embedded into the nanowires. The photocatalytic activity is greatly improved for the AgO/Ag{sub 2}Mo{sub 2}O{sub 7} heterojunction nanowires compared with that of the pure Ag{sub 2}Mo{sub 2}O{sub 7} nanowires, indicating a remarkable role of AgO particles on the Ag{sub 2}Mo{sub 2}O{sub 7} nanowires in the photodegradation.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Ball-milled CuPc/TiO{sub 2} hybrid nanocomposite and its photocatalytic degradation of aqueous Rhodamine B

Graphical abstract: This work reports on the synthesis of hybrid composites of titanium dioxide and copper phthalocyanine via ball-milling assisted process in combination with mechanical mixing process. Their structural properties and photocatalytic degradation of aqueous RhB were investigated. The significant enhancement of the photocatalytic performance of the composite may be related to the charge recombination suppression guiding to the increase of free functional radicals participated in degradation process. Highlights: ► CuPc/TiO{sub 2} nanocomposite was synthesized by ball-milling assisted process and mechanical mixing method. ► Ball milling process can reduce CuPc size and assist the formation of well-dispersed composite. ► Loaded CuPc has inconsiderable influence on basic crystal structure of TiO{sub 2} matrix. ► The optical absorption properties of TiO{sub 2} in UV and visible light is improved with the existence of CuPc. ► CuPc/TiO{sub 2} nanocomposite can efficiently heighten the catalytic performance of TiO{sub 2} in the photodegradation of RhB. -- Abstract: Hybrid composites of titanium dioxide and copper phthalocyanine were synthesized by ball-milling assisted process in combination with mechanically stirring method. Structural properties of as-synthesized composites were characterized by X-ray diffraction (XRD), X-ray absorption fine structure (XANES) and scanning electron microscope (SEM). The optical absorbance of as-prepared composites and their photocatalytic activities were investigated by UV–vis spectroscopy. XRD and XANES results confirm that CuPc/TiO{sub 2} nanocomposite is still in the same structure of TiO{sub 2} and CuPc. SEM result reveals that the decreasing particle size of ball-milled CuPc has good dispersion on the surface of TiO{sub 2}. Absorptivity in UV region of the composites is heightened and shifted to visible light due to strong absorbance in blue-green spectrum of CuPc. The photocatalytic degradation of Rhodamine B dye solution using as-synthesized composites was investigated under ultraviolet irradiation. The optimized condition for RhB photodegradation was obtained for 1 wt.% CuPc/TiO{sub 2} nanocomposite with efficiency of 87.5% and reaction rate of 0.15 min{sup −1}. The significant improvement in photocatalytic activity of the hybrid composite may be associated to the enhancement of optical absorption and the inhibition of electron–hole recombination caused by the presence of CuPc in TiO{sub 2} matrix.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Corrosion inhibitor storage and release property of TiO{sub 2} nanotube powder synthesized by rapid breakdown anodization method

Graphical abstract: Display Omitted Highlights: ► TiO{sub 2} nanotube powders were synthesized by rapid breakdown anodization method. ► Benzotriazole was loaded into the TiO{sub 2} nanotube powders. ► Low pH induced release of benzotriazole from TiO{sub 2} nanotube powders was proved. -- Abstract: Titanium dioxide (TiO{sub 2}) is one of the most studied substances in material science due to its versatile properties and diverse applications. In this study titanium dioxide nanotube powder were synthesized by rapid breakdown anodization (RBA) method. The synthesis involved potentiostatic anodization of titanium foil in 0.1 M HClO{sub 4} electrolyte under an applied voltage of 20 V and rapid stirring. The morphology and the phase of titanium dioxide nanotube powder were studied using field emission scanning electron microscopy, laser Raman spectroscopy and high resolution transmission electron microscopy. Benzotriazole was chosen as model inhibitor to evaluate TiO{sub 2} nanotube powder's corrosion inhibitor loading and releasing properties. The storage and release properties of TiO{sub 2} nanotube powder were studied using UV–visible spectroscopy and thermogravimetric analysis.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2013

Electrochemical synthesis and characterization of zinc oxalate nanoparticles

Highlights: ► Synthesis of zinc oxalate nanoparticles via electrolysis of a zinc plate anode in sodium oxalate solutions. ► Design of a Taguchi orthogonal array to identify the optimal experimental conditions. ► Controlling the size and shape of particles via applied voltage and oxalate concentration. ► Characterization of zinc oxalate nanoparticles by SEM, UV–vis, FT-IR and TG–DTA. - Abstract: A rapid, clean and simple electrodeposition method was designed for the synthesis of zinc oxalate nanoparticles. Zinc oxalate nanoparticles in different size and shapes were electrodeposited by electrolysis of a zinc plate anode in sodium oxalate aqueous solutions. It was found that the size and shape of the product could be tuned by electrolysis voltage, oxalate ion concentration, and stirring rate of electrolyte solution. A Taguchi orthogonal array design was designed to identify the optimal experimental conditions. The morphological characterization of the product was carried out by scanning electron microscopy. UV–vis and FT-IR spectroscopies were also used to characterize the electrodeposited nanoparticles. The TG–DTA studies of the nanoparticles indicated that the main thermal degradation occurs in two steps over a temperature range of 350–430 °C. In contrast to the existing methods, the present study describes a process which can be easily scaled up for the production of nano-sized zinc oxalate powder.

36 MATERIALS SCIENCE↗