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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 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
DOE OSTI2011

Surface composition, microstructure and corrosion resistance of AZ31 magnesium alloy irradiated by high-intensity pulsed ion beam

High-intensity pulsed ion beam (HIPIB) irradiation of AZ31 magnesium alloy is performed and electrochemical corrosion experiment of irradiated samples is carried out by using potentiodynamic polarization technology in order to explore the effect of HIPIB irradiation on corrosion resistance of magnesium alloy. The surface composition, cross-sectional morphology and microstructure are characterized by using electron probe microanalyzer, optical microscope and transmission electron microscope, respectively. The results indicated that HIPIB irradiation leads to a significant improvement in corrosion resistance of magnesium alloy, in terms of the considerable increase in both corrosion potential and pitting breakdown potential. The microstructural refinement and surface purification induced by HIPIB irradiation are responsible for the improved corrosion resistance. - Research Highlights: {yields} A modified layer about 30 {mu}m thick is obtained by HIPIB irradiation. {yields} Selective ablation of element/impurity phase having lower melting point is observed. {yields} More importantly, microstructural refinement occurred on the irradiated surface. {yields} The modified layer exhibited a significantly improved corrosion resistance. {yields} Improved corrosion resistance is ascribed to the combined effect induced by HIPIB.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Formation mechanisms of periodic longitudinal microstructure and texture patterns in friction stir welded magnesium AZ80

Many studies of friction stir welding have shown that periodicity of metal flow around the tool pin may result in the formation of periodic differences in microstructure and texture in the weld nugget area correlated with the weld pitch. The current work investigates the periodicity of magnesium weld microtexture in the nugget region and its association with material flow using optical and electron microscopy. Two welds created in AZ80 at different processing conditions are presented in detail, one illustrating periodic longitudinal texture change, and one showing for the first time that periodic variations in texture, grain size, or composition are not defining features of periodic nugget flow. While nugget texture is dominated by shear deformation, it was found here to be affected to a lesser degree by compaction of material behind the welding tool, which led to reduction in intensity of the shear texture fiber. The decreased tendency for magnesium based alloys to form periodic patterns as compared to aluminum based alloys is explained with reference to the shear textures. - Highlights: •It is shown here that periodic material flow in the nugget does not necessitate longitudinal texture patterns. •Longitudinal texture patterns are shown to be present or absent in Mg AZ80 based on processing conditions. •Texture in the nugget is mainly dictated by shear deformation, but has measurable effects from other deformation modes. •Explanation of why longitudinal texture change is frequently reported in aluminum but not magnesium alloys is provided. •A new vector visualization of material flow based on EBSD data analysis is shown.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Electrochemical properties of magnesium doped LiFePO{sub 4} cathode material prepared by sol–gel method

Magnesium doped Li{sub 1−2x}Mg{sub x}FePO{sub 4}/C (x = 0.00, 0.01, 0.03, 0.05) cathode materials were synthesized by sol–gel method, and the effect of magnesium doping as well as its content on the electrochemical properties for lithium batteries was also investigated{sub .} Their morphology was studied with field emission scanning electron microscope and Li{sub 1−2x}Mg{sub x}FePO{sub 4} materials showed the olivine phase without impurities. The thin carbon layer of Li{sub 1−2x}Mg{sub x}FePO{sub 4}/C was confirmed by high resolution transmission electron microscopy. The magnesium doped Li{sub 1−2x}Mg{sub x}FePO{sub 4}/C particles were smaller than those undoped. The Li{sub 1−2x}Mg{sub x}FePO{sub 4}/C materials showed better cycling behavior than undoped LiFePO{sub 4}, especially at high C-rate in which Li{sub 0.94}Mg{sub 0.03}FePO{sub 4}/C composition exhibited the best electrochemical properties.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Chloride ion-doped polypyrrole nanocomposite as cathode material for rechargeable magnesium battery

Highlights: • Chloride ion-doped polypyrrole nanocomposite is firstly developed as new cathode for rechargeable magnesium battery. • Reversible redox reactions of nitrogen species in nanostructured polypyrrole in RMB system are proved. • More than 95 mAh g{sup −1} capacity and a high Coulombic efficiency of about 96% are delivered. - Abstract: We report a chloride ion-doped polypyrrole/carbon nanotube (PPyCl/CNTs) nanocomposite as new cathode material for rechargeable magnesium battery. The PPyCl/CNTs nanocomposite with amorphous structure, uniform chlorine distribution and large specific surface area shows reversible electrochemical energy storage upon redox reaction of nitrogen species. The structural configuration of PPyCl by the incorporation of CNTs contributes to significant improvement in the electrochemical performance. More than 95 mAh g{sup −1} capacity and a high Coulombic efficiency of about 96% are delivered. This study offers a promising way for designing new cathode for rechargeable magnesium batteries.

25 ENERGY STORAGE↗
DOE OSTI2017

Hot deformation characteristics of AZ80 magnesium alloy: Work hardening effect and processing parameter sensitivities

Isothermal compression experiment of AZ80 magnesium alloy was conducted by Gleeble thermo-mechanical simulator in order to quantitatively investigate the work hardening (WH), strain rate sensitivity (SRS) and temperature sensitivity (TS) during hot processing of magnesium alloys. The WH, SRS and TS were described by Zener-Hollomon parameter (Z) coupling of deformation parameters. The relationships between WH rate and true strain as well as true stress were derived from Kocks-Mecking dislocation model and validated by our measurement data. The slope defined through the linear relationship of WH rate and true stress was only related to the annihilation coefficient Ω. Obvious WH behavior could be exhibited at a higher Z condition. Furthermore, we have identified the correlation between the microstructural evolution including β-Mg17Al12 precipitation and the SRS and TS variations. Intensive dynamic recrystallization and homogeneous distribution of β-Mg17Al12 precipitates resulted in greater SRS coefficient at higher temperature. The deformation heat effect and β-Mg17Al12 precipitate content can be regarded as the major factors determining the TS behavior. At low Z condition, the SRS becomes stronger, in contrast to the variation of TS. The optimum hot processing window was validated based on the established SRS and TS values distribution maps for AZ80 magnesium alloy.

36 MATERIALS SCIENCE↗
DOE OSTI2020

A new magnesium sheet alloy with high tensile properties and room-temperature formability

Lightweight sheet alloys with superior mechanical performance such as high strength, ductility and formability at room temperature (RT) are desirable for high volume automotive applications. However, ductility or formability of metallic alloys at RT are generally inversely related to strength, thereby making it difficult to optimize all three simultaneously. Here we design a new magnesium sheet alloy-ZAXME11100 (Mg-1.0Zn-1.0Al-0.5Ca-0.4Mn-0.2Ce, wt. pct.) via CALPHAD (CALculation of PHAse Diagram) modeling and experimental validation. This new sheet alloy offers an excellent RT formability with a high Index Erichsen (I.E.) value of 7.8 mm in a solution-treated condition (T4), due to its weak and split basal texture and fine grain structure. The new ZAXME 11100 alloy also shows a rapid age-hardening response during post-forming artificial aging treatment at 210 °C for 1hour (T6), resulting in a significant increase of yield strength from 159 MPa (T4) to 270 MPa (T6). The excellent combination of T4 ductility (31%), T4 formability (7.8 mm) and T6 yield strength (270 MPa) in this new magnesium alloy is comparable to that of common 6xxx series aluminum sheet alloys. Thus, this new magnesium sheet alloy is highly attractive for sheet applications in automotive and other industries.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Coordination Chemistry in magnesium battery electrolytes: how ligands affect their performance

Magnesium battery is potentially a safe, cost-effective, and high energy density technology for large scale energy storage. However, the development of magnesium battery has been hindered by the limited performance and the lack of fundamental understandings of electrolytes. Here, we present a coordination chemistry study of Mg(BH 4 ) 2 in ethereal solvents. The O donor denticity, i.e. ligand strength of the ethereal solvents which act as ligands to form solvated Mg complexes, plays a significant role in enhancing coulombic efficiency of the corresponding solvated Mg complex electrolytes. A new and safer electrolyte is developed based on Mg(BH4)2, diglyme and optimized LiBH4 additive. The new electrolyte demonstrates 100% coulombic efficiency, no dendrite formation, and stable cycling performance with the cathode capacity retention of ~90% for 300 cycles in a prototype magnesium battery.

25 ENERGY STORAGE↗
DOE OSTI2011

Producing Magnesium Metallic Glass By Disintegrated Melt Deposition

Bulk metallic glasses are new class of engineering materials that exhibit high resistance to crystallization in the under cooled liquid state. The development of bulk metallic glasses of thickness 1cm or less has opened new doors for fundamental studies of both liquid state and glass transition previously not feasible in metallic materials. Moreover, bulk metallic glasses exhibit superior hardness, strength, specific strength, and elastic strain limit, along with good corrosion and wear resistance. Thus they are potential candidates in various sports, structural, engineering and medical applications. Among several BMGs investigated, magnesium-based BMGs have attracted considerable attention because of their low density and superior mechanical properties. The major drawback of this magnesium based BMGs is poor ductility. This can be overcome by the addition of ductile particles/reinforcement to the matrix. In this study, a new technique named disintegrated melt deposition technique was used to synthesize magnesium based BMGs. Rods of different sizes are cast using the current method. Mechanical characterization studies revealed that the amorphous rods produced by the current technique showed superior mechanical properties.

36 MATERIALS SCIENCE↗
DOE OSTI2011

Study of Forming of Magnesium Alloy by Explosive Energy

Magnesium alloy is an attractive next generation material due to its high specific strength with low weight. However, magnesium alloys has few slip lines with close-packed hexagonal lattice, and generally poor ductility at room temperature, therefore it is difficult to form this material by cold forging. It is well known that the speed of deformation of metallic materials rapidly changes at the high strain rate. For some metallic materials, it is reported that the ductility also increases at the high strain rate with this speed effect. In this study, a series of high speed impulsive compressive tests were carried. By using explosives for shock wave loading, the velocity in this experiment reached 100 m/s that can't be easily obtained in normal experiment. In this paper, the possibility of forming the AZ31 extrusion magnesium alloy using explosive-impulsive pressure is investigated. And improved ductility by the effect of high-rate deformation is observed with this alloy.

36 MATERIALS SCIENCE↗
DOE OSTI2011

Tribology and Tool Wear of Hot Dip Galvanized Zinc Magnesium Alloys on Cold Rolled Steel Sheets

Recently zinc based coatings on cold rolled steel with improved functionality in terms of forming and/or corrosion behaviour have been intensively investigated in the steel industry. One of the most promising products are zinc magnesium alloys produced in hot dip galvanizing process. These coatings were already introduced in construction industry a few years ago. With some modifications the improved properties of the coating are also interesting for automotive industry. In the present work the tribological potential of hot dip galvanized zinc magnesium coatings (HDG/ZM) produced at an industrial line under regular production, was studied in terms of sliding properties, adhesive and abrasive tool wear.First a short introduction into surface morphology of HDG/ZM will be given. For the tribological characterization of the material, which is the main topic of the contribution, different tests were performed on hot dip galvanised zinc magnesium material and results were compared with classic hot dip galvanized zinc coating (HDG/Z). The investigations are mainly based on the strip draw test which allows the determination of the friction coefficient directly by using a constant contact pressure. Deep drawing property was tested by forming model cups. The abrasive tool wear was tested using a standard test for material used in automotive industry. The adhesive tool wear was investigated by characterizing the coating material transferred to the tool in the strip draw test.All performed tests show an improved drawability of HDG/ZM compared to classical HDG/Z reference material. However the most promising difference between HDG/ZM and HDG/Z is that galling was found to be less for HDG/ZM than for HDG/Z. Therefore HDG/ZM is an interesting system not only with respect to corrosion protection but also in terms of tribology and provides clear advantages in formability.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Influence of Si Co-doping on electrical transport properties of magnesium-doped boron nanoswords

Magnesium-doped boron nanoswords were synthesized via a thermoreduction method. The as-prepared nanoswords are single crystalline and {beta}-rhombohedral ({beta}-rh) phase. Electrical transport measurements show that variable range hopping conductivity increases with temperature, and carrier mobility has a greater influence than carrier concentration. These results are consistent with the three dimensional Mott's model (M. Cutler and N. F. Mott, Phys. Rev. 181, 1336 (1969)) besides a high density of localized states at the Fermi level compared with bulk {beta}-rh boron. Conductivity of Mg-doped boron nanoswords is significantly lower than that of ''pure'' (free of magnesium) boron nanoswords. Electron energy loss spectroscopy studies confirm that the poorer conductivity arises from silicon against magnesium doping.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Cohesion enhancing effect of magnesium in aluminum grain boundary: A first-principles determination

The effect of magnesium on grain boundary cohesion in aluminum was investigated by means of first-principles calculations using the Rice-Wang model [Rice and Wang, Mater. Sci. Eng. A 107, 23 (1989)]. It is demonstrated that magnesium is a cohesion enhancer with a potency of -0.11 eV/atom. It is further determined through electronic structure and bonding character analysis that the cohesion enhancing property of magnesium is due to a charge transfer mechanism which is unusually strong and overcomes the negative result of the size effect mechanism. Consistent with experimental results, this work clarifies the controversy and establishes that Mg segregation does not contribute to stress corrosion cracking in Al alloys.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Dosimetric properties of dysprosium doped calcium magnesium borate glass subjected to Co-60 gamma ray

Thermoluminescence (TL) dosimetric properties of dysprosium doped calcium magnesium borate (CMB:Dy) glass are presented. This study is deemed to understand the application of calcium as the modifier in magnesium borate glass with the presence of dysprosium as the activator to be performed as TL dosimeter (TLD). The study provides fundamental knowledge of a glass system that may lead to perform new TL glass dosimetry application in future research. Calcium magnesium borate glass systems of (70-y) B{sub 2}O{sub 3} − 20 CaO – 10 MgO-(y) Dy{sub 2}O{sub 3} with 0.05 mol % ≤ y ≤ 0.7 mol % of dyprosium were prepared by melt-quenching technique. The amorphous structure and TL properties of the prepared samples were determined using powder X-ray diffraction (XRD) and TL reader; model Harshaw 4500 respectively. The samples were irradiated to Co-60 gamma source at a dose of 50 Gy. Dosimetric properties such as annealing procedure, time temperature profile (TTP) setting, optimization of Dy{sub 2}O{sub 3} concentration of 0.5 mol % were determined for thermoluminescence dosimeter (TLD) reader used.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2018

Preparation of Exfoliated Graphite Modified with Magnesium Ferrite

A magnetic sorbent based on exfoliated graphite modified with magnesium ferrite has been prepared by impregnating oxidized graphite in a mixed solution of FeCl{sub 3} and Mg(NO{sub 3}){sub 2}, followed by heat treatment of the impregnated oxidized graphite in air. X-ray diffraction and Mössbauer spectroscopy results demonstrate that the structure of the magnesium ferrite is an inverse spinel with a degree of inversion of 0.59. The saturation magnetization of the magnesium ferrite-containing exfoliated graphite is 16.1 emu/g, whereas its oil sorption capacity is as high as 54 g/g. Compaction of the exfoliated graphite to a density of 0.03 g/cm{sup 3} reduced its sorption capacity to 26 g/g. Further increasing the density of the material led to a considerable decrease in its sorption capacity.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Luminescence Quenching in Magnesium-Doped Alumina Ceramics

The effect of magnesium impurity on luminescent properties of alumina ceramics sintered at high temperatures under vacuum is studied by pulsed cathodoluminescence, photoluminescence, and thermoluminescence. At dopant concentrations >1 wt %, high-temperature synthesis results in formation of defects associated with magnesium, which were identified in the pulsed cathodoluminescence (520 nm) and photoluminescence (767 nm) spectra, as well as in the thermoluminescence curves (380 K). It is found that increased magnesium concentration leads to luminescence quenching of the intrinsic centers (F centers) of alumina in the PCL emission band at 400 nm, impurity defects (Mn{sup 4+} and Cr{sup 3+}) in the photoluminescence emission bands at 673 and 689 nm, and all the recorded thermoluminescence peaks at 380, 450, and 615 K.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2016

Communication—Sol-Gel Synthesized Magnesium Vanadium Oxide, Mg x V 2 O 5 · nH 2 O: The Role of Structural Mg 2+ on Battery Performance

Magnesium intercalated vanadium oxide xerogels, Mg 0.1 V 2 O 5 · 2.35H 2 O and Mg 0.2 V 2 O 5 · 2.46H 2 O were synthesized using an ion removal sol gel strategy. X-ray diffraction indicated lamellar ordering with turbostratic character. X-ray absorption spectroscopy indicated greater distortion of the vanadium-oxygen coordination environment in Mg 0.2 V 2 O 5 · 2.46H 2 O. Elemental analysis after cycling in Li + or Mg 2+ based electrolytes revealed that the magnesium content was unchanged, indicating structural Mg 2+ are retained. Furthermore, the Mg 0.1 V 2 O 5 · 2.35H 2 O material displayed high voltage, energy density, and discharge/charge efficiency, indicating promise as a cathode material for future magnesium based batteries.

25 ENERGY STORAGE↗
DOE OSTI2014

Lightweight Materials for Automotive Application: An Assessment of Material Production Data for Magnesium and Carbon Fiber

The use of lightweight materials in vehicle components, also known as “lightweighting,” can result in automobile weight reduction, which improves vehicle fuel economy and generally its environmental footprint. Materials often used for vehicle lightweighting include aluminum, magnesium, and polymers reinforced with either glass or carbon fiber. However, because alternative materials typically used for vehicle lightweighting require more energy to make on a per part basis than the material being replaced (often steel or iron), the fuel efficiency improvement induced by a weight reduction is partially offset by an increased energy for the vehicle material production. To adequately quantify this tradeoff, reliable and current values for life-cycle production energy are needed for both conventional and alternative materials. Our focus here is on the production of two such alternative materials: magnesium and carbon fibers. Both these materials are low density solids with good structural properties. These properties have enabled their use in applications where weight is an issue, not only for automobiles but also for aerospace applications. This report addresses the predominant production methods for these materials and includes a tabulation of available material and energy input data necessary to make them. The life cycle inventory (LCI) information presented herein represents a process chain analysis (PCA) approach to life cycle assessment (LCA) and is intended for evaluation as updated materials production data for magnesium and carbon fiber for inclusion into the Greenhouse gases, Regulated Emissions, and Energy use in Transportation model (GREET2_2012). The summary life-cycle metrics used to characterize the cradle-to-gate environmental performance of these materials are the cumulative energy demand (CED) and greenhouse gas emissions (GHG) per kilogram of material.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2024

Development of Magnesium Oxysulfate Formulation for SRPPF Aqueous Recovery Liquid Solidification

The liquid effluent from the Savannah River Plutonium Processing Facility (SRPPF) Aqueous Recovery Processes will be solidified into a stable form that is acceptable by Waste Isolation Pilot Plant (WIPP) for disposal. The current Aqueous Recovery flow sheet proposes to solidify the liquid effluent using a grout formula that was developed and tested for the former Waste Solidification Building process. This Portland cement based mixture results in a high pH (~13) leachate from the solidified waste form which is not acceptable to WIPP in the large quantities expected from production at SRPPF. Various cementitious materials were previously evaluated as alternative grout formulations to Portland cement and a MgO-based mix was identified as a promising alternative. A magnesium oxysulfate (MOS) cement formulation comprised of reactive magnesium oxide (MgO), anhydrous magnesium sulfate (MgSO 4 ), and sand, as a non-reactive heat sink provided good mixability, similar density to the original Portland-cement based mix, and a leachate pH of 9.4, within the assumed WIPP brine pH range. However, the MOS formulation exhibited an appreciable amount of heat generation, which resulted in premature setting of a large-scale test.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗