Reduction of Gd6UO12 for the Synthesis of Gd6UO11

2013 ◽  
Vol 1514 ◽  
pp. 151-156
Author(s):  
Darío Pieck ◽  
Lionel Desgranges ◽  
Yves Pontillon ◽  
Pierre Matheron
Keyword(s):  
Heat Treatment ◽  
Xrd Analysis ◽  
Decomposition Products ◽  
Air Atmosphere ◽  
Reducing Conditions ◽  
Reducing Environment

ABSTRACTIn the present work, we focus on δ-Gd6UO12 phase and its stability under reducing conditions. This later point is interesting regarding reducing environment that could exist in some nuclear storage sites and that could possibly degrade δ–compounds. A polycrystalline δ-Gd6UO12 sample was prepared by sintering cubic-Gd2O3 and UO2 mixed powders under an air atmosphere. The resulting pellets were then characterized and reduced by heat treatment under an Ar with H2 5% atmosphere. XRD analysis of the sample after reduction did not confirm the reduction into Gd6UO11 but a decomposition of the δ-compound. Preliminary characterizations of these decomposition products are presented.

NATIVE METALS IN THE MUSKOX INTRUSION

1965 ◽  
Vol 2 (3) ◽  
pp. 188-215 ◽  
Author(s):  
J. A. Chamberlain ◽  
C. R. McLeod ◽  
R. J. Traill ◽  
G. R. Lachance
Keyword(s):  
Experimental Studies ◽  
Native Metal ◽  
Native Copper ◽  
Nickel Iron ◽  
Native Iron ◽  
Reducing Conditions ◽  
Cobalt Iron ◽  
Central Regions ◽  
Reducing Environment

The following native metals have been identified in the Muskox intrusion: native iron, native nickel–iron (awaruite), native cobalt–iron (wairauite), and native copper. Mineral distributions and textures indicate that the native metals formed more or less contemporaneously, during the period of serpentinization of the host dunites and related rocks.Conditions during serpentinization must have been more reducing in the central and lower parts of the layered series than in the margins and upper parts of the intrusion. This is indicated by the fact that most native metals are abundant in the central regions and are essentially lacking elsewhere, even in strongly serpentinized zones. This zoning suggests that reducing conditions may have been generated internally, possibly as a result of the serpentinization process itself. The composition of the primary olivine of forsterite80–88 together with the presence of abundant secondary magnetite in equivalent serpentinites indicates that a redox reaction, olivine + water = serpentine + magnetite + hydrogen, contributed to the development of a progressively more reducing, or hydrogen-rich, fluid phase.Natural phase relations indicate that each native metal formed primarily in situ as a result of the decomposition of specific earlier formed minerals that had become unstable in the reducing environment. Native iron appears to have been formed by the reduction of magnetite; awaruite by the reduction of pentlandite; wairauite by the reduction of an unknown phase, possibly cobalt pentlandite or cobaltian pyrite; and native copper by the reduction of chalcopyrite. The feasibility of most of these reactions was confirmed by experimental studies carried out in systems open to moist hydrogen.

Mechanical Behaviour of Gas Nitrided Ti6Al4V Bars Produced by Selective Laser Melting

2016 ◽  
Vol 704 ◽  
pp. 225-234 ◽  
Author(s):  
Peter Franz ◽  
Aamir Mukhtar ◽  
Warwick Downing ◽  
Graeme Smith ◽  
Ben Jackson
Keyword(s):  
Heat Treatment ◽  
Selective Laser Melting ◽  
Nitrided Layer ◽  
Xrd Analysis ◽  
Compound Layer ◽  
Processing Parameters ◽  
Heat Treatments ◽  
Laser Melting ◽  
Gas Nitriding ◽  
Heat Treated

Gas atomized Ti-6Al-4V (Ti64) alloy powder was used to prepare distinct designed geometries with different properties by selective laser melting (SLM). Several heat treatments were investigated to find suitable processing parameters to strengthen (specially to harden) these parts for different applications. The results showed significant differences between tabulated results for heat treated billet Ti64 and SLM produced Ti64 parts, while certain mechanical properties of SLM Ti64 parts could be improved by different heat treatments using different processing parameters. Most heat treatments performed followed the trends of a reduction in tensile strength while improving ductility compared with untreated SLM Ti64 parts.Gas nitriding [GN] (diffusion-based thermo-chemical treatment) has been combined with a selected heat treatment for interstitial hardening. Heat treatment was performed below β-transus temperature using minimum flow of nitrogen gas with a controlled low pressure. The surface of the SLM produced Ti64 parts after gas nitriding showed TiN and Ti2N phases (“compound layer”, XRD analysis) and α (N) – Ti diffusion zones as well as high values of micro-hardness as compared to untreated SLM produced Ti64 parts. The microhardness profiles on cross section of the gas nitrided SLM produced samples gave information about the i) microhardness behaviour of the material, and ii) thickness of the nitrided layer, which was investigated using energy dispersive spectroscopy (EDS) and x-ray elemental analysis. Tensile properties of the gas nitrided Ti64 bars produced by SLM under different conditions were also reported.

The Effect of Heat Treatment on the Optical Properties of Copper-Containing Lithium-Potassium-Borate Glasses

2018 ◽  
Vol 57 (1) ◽  
pp. 116-120
Author(s):  
P.S. Shirshnev ◽  
V.L. Ugolkov ◽  
Zh.G. Snezhnaia ◽  
D.I. Panov ◽  
E.V. Shirshneva-Vaschenko ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Optical Properties ◽  
Raman Scattering ◽  
Copper Ions ◽  
Xrd Analysis ◽  
Luminescence Spectra ◽  
Borate Glasses ◽  
Potassium Borate ◽  
Narrow Bands

Abstract The paper presents the investigation of lithium-potassium-alumoborate glasses (0- 25 mol.% Li2O) doped by copper ions. The effect of glass annealing on the Raman scattering patterns is discussed. It is shown that such an annealing results in drastic changes in the Raman scattering patterns for the glass with 10 mol.%of Li2O: the band at 481 cm-1 conventionally attributed to boron-oxygen bonds in metaborate rings disappears, while a set of narrow bands at 1236, 1500, and 1783 cm-1 is observed. We consider one of these bands, 1783 cm-1, as being the identifier of the formed Li(Al7B4O17) nanophase, XRD analysis supported the above suggestion. The effect of newly formed nanophase on the luminescence spectra is discussed.

scholarly journals Influence of Heat Treatment on the Corrosion Resistance of Aluminum-Copper Coating

Metals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 966
Author(s):  
Mieczyslaw Scendo ◽  
Slawomir Spadlo ◽  
Katarzyna Staszewska-Samson ◽  
Piotr Mlynarczyk
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Corrosion Resistance ◽  
Electrochemical Corrosion ◽  
X Ray Diffraction ◽  
Air Atmosphere ◽  
Cu Alloy ◽  
Acidic Chloride Solution ◽  
Acidic Chloride ◽  
Electrical Discharge Alloying

Influence of heat treatment on the corrosion resistance of the aluminum-copper (Al-Cu) coating on the aluminum substrate was investigated. The coating was produced by the electrical discharge alloying (EDA) method. The surface and microstructure of the specimens were observed by a scanning electron microscope (SEM). The phase analysis of the composite materials by X-ray diffraction (XRD) and energy-dispersive spectroscopy (EDS) indicated that intermetallic compounds (i.e., CuAl2 and Cu9Al4) were formed through reactions between Al and Cu. during the EDA process. A significant increase in the hardness of the Al-Cu coating was affected by the improvement of the alloy structure. The heat treatment of materials was carried out at 400 °C or 600 °C in the air atmosphere. A corrosion test of materials was carried out by using electrochemical methods. The corrosive environment was acidic chloride solution. After heat treatment at 400 °C the mechanical properties of the Al/Cu alloy increased significantly and the oxide layer protect of the alloy surface against corrosion. However, after heat treatment at elevated temperature, i.e., 600 °C it was found that the (Al2O3)ads and (CuO)ads coatings were destroyed. The mechanical properties of the Al/Cu alloy decreased, and its surface has undergone deep electrochemical corrosion.

In Vitro Bioactivity Characterization of Machinable Glass Ceramics Containing 85wt% Na-mica and 15wt% Fluorapatite

2006 ◽  
Vol 309-311 ◽  
pp. 325-328 ◽  
Author(s):  
Gültekin Göller ◽  
Ipek Akin ◽  
A. Kahraman ◽  
Erdem Demirkesen ◽  
M. Urgen
Keyword(s):  
Thin Film ◽  
Heat Treatment ◽  
Glass Ceramic ◽  
Glass Ceramics ◽  
Xrd Analysis ◽  
Crystallization Time ◽  
In Vitro Bioactivity ◽  
Treatment Procedures

In this study; in-vitro bioactivity characterization of machinable glass-ceramics having 85 wt% sodium mica (NaMg3AlSi3O10F2) and 15 wt% fluoroapatite has been carried out. Two different heat treatment procedures are applied to the machinable glass-ceramics. The first one is nucleation at 610°C for 2 hours and crystallization at 1000°C for 3 hours and the second is nucleation at 610°C for 2 hours and crystallization at 1000°C for 4 hours. It is observed that increasing the crystallization time to 4 hours resulted in the increasing the formation of hydroxyapatite layer on surface. According to the microstructural investigations, the morphology of the precipitated crystals are different. In addition, the speed of the precipitation of hydroxyapatite is higher in glass-ceramic B than A. Thin film XRD analysis supports these results.

scholarly journals Effect of Oxidation Rate and Fe(II) State on Microbial Nitrate-Dependent Fe(III) Mineral Formation

2005 ◽  
Vol 71 (11) ◽  
pp. 7172-7177 ◽  
Author(s):  
John M. Senko ◽  
Thomas A. Dewers ◽  
Lee R. Krumholz
Keyword(s):  
Oxidation Rate ◽  
Sequence Similarity ◽  
Klebsiella Oxytoca ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
16S Rrna Sequence ◽  
X Ray ◽  
Oxidation Rates ◽  
Reducing Conditions

ABSTRACT A nitrate-dependent Fe(II)-oxidizing bacterium was isolated and used to evaluate whether Fe(II) chemical form or oxidation rate had an effect on the mineralogy of biogenic Fe(III) (hydr)oxides resulting from nitrate-dependent Fe(II) oxidation. The isolate (designated FW33AN) had 99% 16S rRNA sequence similarity to Klebsiella oxytoca. FW33AN produced Fe(III) (hydr)oxides by oxidation of soluble Fe(II) [Fe(II)sol] or FeS under nitrate-reducing conditions. Based on X-ray diffraction (XRD) analysis, Fe(III) (hydr)oxide produced by oxidation of FeS was shown to be amorphous, while oxidation of Fe(II)sol yielded goethite. The rate of Fe(II) oxidation was then manipulated by incubating various cell concentrations of FW33AN with Fe(II)sol and nitrate. Characterization of products revealed that as Fe(II) oxidation rates slowed, a stronger goethite signal was observed by XRD and a larger proportion of Fe(III) was in the crystalline fraction. Since the mineralogy of Fe(III) (hydr)oxides may control the extent of subsequent Fe(III) reduction, the variables we identify here may have an effect on the biogeochemical cycling of Fe in anoxic ecosystems.

scholarly journals XRD and CO2 Adsorption Studies of Modified Silica Gel with Octadecylamine

2017 ◽  
Vol 888 ◽  
pp. 529-533
Author(s):  
Maratun Najiha Abu Tahari ◽  
Azizul Hakim ◽  
Tengku Sharifah Marliza ◽  
Nurul Hanisah Mohd ◽  
Mohd Ambar Yarmo
Keyword(s):  
Heat Treatment ◽  
Silica Gel ◽  
Xrd Analysis ◽  
Straight Chain ◽  
Modified Silica Gel ◽  
Wet Impregnation ◽  
Impregnation Process ◽  
Process Characterization ◽  
Amine Compounds ◽  
Adsorption Desorption

Porous surface of silica gel (SG) have been modified with long and straight chain fatty amine compounds (octadecylamine, ODA) via wet impregnation process. SG was undergo heat treatment with various temperature which are 100, 200, 400 and 600 °C before continuing with impregnation process. Characterization by XRD of the treated samples were showed no significant different in their diffractograms. The best temperature for heat treatment was 600 °C and it was referred to the ability of the SG600 type adsorbents in adsorbing CO2 resulted from adsorption desorption isotherm of CO2. The 5 and 35 wt. % of ODA supported on the SG (ODA/SG600) was further characterized using XRD analysis which displayed the increasing intensity of crystalline ODA with higher percent amine loaded and shifting of the several crystalline peak of ODA verified the interaction of SG600-ODA. These further strengthen the prevailing dispersion of ODA on the surface of SG600.

Phase Constitution and Heat Treatment Behavior of Titanium-Manganese Alloys

2010 ◽  
Vol 638-642 ◽  
pp. 425-430 ◽  
Author(s):  
Masahiko Ikeda ◽  
Masato Ueda ◽  
Ryuichi Matsunaga ◽  
Michiharu Ogawa ◽  
Mitsuo Niinomi
Keyword(s):  
Heat Treatment ◽  
Titanium Alloys ◽  
Vickers Hardness ◽  
Xrd Analysis ◽  
Rare Metal ◽  
Positive Temperature ◽  
Resistivity Ratio ◽  
Phase Constitution ◽  
Mn Content ◽  
Increasing Temperature

Although titanium is considered to be a ubiquitous element since it has the tenth highest Clarke number of all elements, it is classified as a rare metal because the current refinement process is more environmentally damaging than the processes used to refine iron and aluminum. Furthermore, the beta stabilizing elements of titanium alloys (e.g., V, Mo, Nb, and Ta) are very expensive due to their low crustal abundances. Manganese is also considered to be a ubiquitous element, since it has the 12th highest Clarke number of all elements. Therefore, manganese is a promising alloying element for titanium, especially as a beta-stabilizer. In order to develop beta titanium alloys as ubiquitous metallic materials, it is very important to investigate the properties of Ti-Mn alloys. In this study, the phase constitution of and the effect of heat treatment on Ti-3.3 to 8.7 mass% Mn alloys were investigated by electrical resistivity and Vickers hardness (HV) measurements and by X-ray diffraction (XRD) analysis and optical microscopy. In 3.3, 5.1, and 6.0 mass% Mn alloys quenched from 1173 K, ’ martensite and  phase were identified by XRD, whereas in the 8.7 mass% alloy, only the  phase was detected. The resistivities at both temperatures increased with increasing Mn content up to 6.0 mass% Mn and the positive temperature dependence of resistivity became negative at 6.0 mass% Mn. LN increased gradually with increasing Mn content up to 8.7 mass% Mn, whereasRT decreased considerably at a Mn content of 8.7 mass% Mn. HV increased with increasing Mn content up to 5.1 mass%, after which it began to decrease. In Ti-3.3 mass%Mn and 5.1 mass%Mn alloys, the resistivity and the resistivity ratio decreased with increasing temperature of isochronal heat treatment because of decomposition of ’ martensite. In 6.0Mn and 8.7Mn alloys, the resistivity and the resistivity ratio decreased, while Vickers hardness increased with increasing temperature of isochronal heat treatment because of isothermal  precipitation. Furthermore, the temperature for the onset of precipitation increased with higher Mn content.

Effect of Ti Addition on Oxidation Behavior and Area Specific Resistance of Fe-20Cr Alloys for SOFC Interconnects

2014 ◽  
Vol 660 ◽  
pp. 249-253 ◽  
Author(s):  
Zaka Ruhma ◽  
Asep Ridwan Setiawan ◽  
Aditianto Ramelan ◽  
Rochim Suratman
Keyword(s):  
Oxidation Behavior ◽  
Specific Resistance ◽  
Parabolic Rate Constant ◽  
Xrd Analysis ◽  
Oxidation Rates ◽  
Air Atmosphere ◽  
Ti Alloys ◽  
Initial Stage ◽  
Area Specific Resistance ◽  
Ti Addition

In this work, the oxidation behavior of Fe-20wt.%Cr alloys with different titanium contents: 0, 0.5, and 1 wt.% are studied as a function of time in air atmosphere. The samples were isothermally oxidized at 700°C for 24, 48, and 96 h in a box furnace. The area specific resistance of oxides formed at the alloys surface during oxidation is measured by four-point probe methods at 700°C for 24 h. For Ti containing alloys, surface morphology observation by SEM shows that a few of TiO2 particles formed on the top of Cr2O3 scales. Continous TiO2 layer was not formed at the alloys surface after oxidation. XRD analysis on the oxide scales of Fe-20Cr-Ti alloys confirms that Cr2O3 and TiO2 oxide formed on the alloys. Ti addition into the alloys increases the oxidation rates of alloys at the initial stages. Oxidation behavior of Fe-20Cr-0.5Ti and Fe-20Cr-1Ti alloys showed two regimes. The parabolic rate constant, kp (in gr2/cm4s) were 1.57 x 10-13 and 3.08 x 10-13 respectively for initial stage of oxidation then changed to-9 x 10-15 and-3 x 10-14 respectively for the remainder of the test. ASR measurement shows that the presence of Ti in the alloys decreases the electrical resistance up to 60%. Ti addition into Fe-Cr alloys affect the oxide growth rate and increase the conductivity of Cr2O3 scales.

Preparation of SiO2-Na2O-CaO-P2O5 Glass-Ceramic from Waste Materials and Heat Treatment Effects on its Morphology

2016 ◽  
Vol 846 ◽  
pp. 189-192 ◽  
Author(s):  
Nur Fadilah Baharuddin Pallan ◽  
Khamirul Amin Matori ◽  
Mansor Hashim ◽  
Way Foong Lim ◽  
Hock Jin Quah ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Glass Ceramic ◽  
New Technologies ◽  
Density Measurement ◽  
Soda Lime ◽  
Xrd Analysis ◽  
Diffraction Peak ◽  
Main Phase ◽  
Waste Materials ◽  
Crystal System

Currently, many researchers interested studying waste materials to recycle them or reuse them in new products. From the sustainable perspective development, it is necessary to implement new technologies to help reduce waste and thus minimize the environmental problems associated with disposal. In this study, the preparation of SiO2-Na2O-CaO-P2O5 (SNCP) glass-ceramic is composed of Soda Lime Silicate (SLS), Clam Shell (CS), Na2CO3 and P2O5 in the ratio of 50: 25: 20: 5 respectively. The waste materials that were used for fabricate glass-ceramic are SLS and CS. All the compounds were mixed to fabricate the SNCP glass-ceramic through solid state reaction. The samples were investigated through X-ray diffraction (XRD), field emission microscope (FESEM) and density measurement. The samples were sintered at temperature 550°C, 650°C, 750°C, 850°C until 950°C. The main phase obtained from XRD analysis is Sodium Calcium Silicate, Na2CaSiO4 with cubic crystal system at 550°C. The highest intensity phase of the diffraction peak is (220) and at the angle 33.7°. There was new peak presence at right side of the main phase Na2CaSiO4, which belong to Silicon Phosphate, SiP2O7 at 650°C and 750°C.When heat treatment increased at 850°C - 950°C, the main phase is Combeite, Na4Ca4(Si6O18) at diffraction peak (220) with rhombohedral crystal system which is assigned to high crystallization temperature (Tc). The density of samples increases at 550°C - 750°C and decreases when heat treatment 850°C - 950°C. Sample density decreases at heat treatment 850°C - 950°C due to increases of sample lattice parameter. FESEM analysis showed that the grain size and porosity increased when the heat treatment increased.

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