Reaction aureoles around uraninites within biotite and plagioclase: evidence of low-temperature sequential fluid alteration and LREE-mobilization from monazite

2016 ◽  
Vol 80 (4) ◽  
pp. 567-584 ◽  
Author(s):  
Manoj K. Ozha ◽  
Biswaji Mishra ◽  
Aiveliagaram V. Jeyagopal
Keyword(s):  
Low Temperature ◽  
Secondary Phases ◽  
Alpha Radiation ◽  
Fluid Infiltration ◽  
The Matrix ◽  
Fluid Alteration ◽  
Simulation Results ◽  
Radial Cracks ◽  
Penetration Depths ◽  
Intense Radiation

AbstractOptical microscopy, Raman spectroscopy and electron probe microanalyses were conducted on a migmatitic metapelite to investigate the effects of alpha radiation and subsequent alteration at the interface between uraninite inclusions and the host minerals biotite, chlorite and albitic plagioclase. The study reveals (1) anomalous colouration under the polarizing microscope; (2) pertinent changes in the characteristic Raman spectra of host phases; (3) reaction aureoles, composed of secondary phases (viz. chlorite and K-feldspar) of various sizes (∼15–45 μm) within biotite and plagioclase, respectively; (iv) K-feldspatization and sericitization of plagioclase at the grain boundaries; (5) agreement between the observed α-penetration depths and the Monte-Carlo simulation results; and (6) dissolution textures within the matrix monazites. Analysis of the compositions of the reaction aureoles in albitic plagioclase reveals a systematic distribution of K-feldspar-, LREE- and clay-rich zones; while the same in biotite is composed of secondary chlorite. The growth sequence of the secondary phases indicates an influx of a K-rich fluid, following intense radiation damage, efficiently superimposed by LREE-metasomatism and later acidic alteration. These changes took place under low-temperature (≤150°C) conditions, wherein radial cracks (within plagioclase) and cleavages/fractures (within biotite) favoured fluid infiltration-circulation into the reaction aureoles. Depletion of the LREEs from the dissolved matrix monazites and their enrichment as a discrete LREE phase within the damaged aureoles in plagioclase demonstrate micrometre-scale LREE mobility.

Low temperature fluid alteration of oceanic layer 2 basalts, DSDP Leg 37

1977 ◽  
Vol 14 (4) ◽  
pp. 911-926 ◽  
Author(s):  
A. J. Andrews
Keyword(s):  
Low Temperature ◽  
Chemical Nature ◽  
Sea Water ◽  
Significant Rise ◽  
Secondary Phases ◽  
Acoustic Basement ◽  
Layer 2 ◽  
Fluid Alteration ◽  
Fluid Interaction ◽  
Mineralogical Evidence

Penetration of cold seawater into layer 2 of the oceanic crust occurs to at least 600 m, the maximum depth drilled below the sediment-acoustic basement boundary during Leg 37 of the DSDP. The main alteration phases are Mg-saponite, Fe-K rich celadonite, phillipsite, calcite, and hematite. The only exception to this occurs in the form of intensely hydrothermally altered gabbro breccias from an intrusive complex at site 334. There is no mineralogical evidence to suggest an increase in metamorphic grade with depth; however, a variation in mineralogy and alteration intensity, occurs as a function of structure, permeability, and the chemical nature of rock-fluid interaction. On this basis three types of alteration are defined as follows: (A) fracture focussed, oxidative; (B) palagonitic; and (C) non-oxidative, pervasive.Electron microprobe analyses reveal that alteration of fresh glass to palagonite involves the addition of H2O, an increase in total Fe, K2O, TiO2, and possibly SiO2, and the loss of CaO, MgO, Na2O, and MnO.Detailed examination of the mineralogy and chemistry of oxidative alteration suggests that during low temperature sea water–basalt interaction, basalt experiences a net gain in CaO, total Fe and K2O, while SiO2 and MgO appear to have been locally remobilized. These trends are generally consistent with the distribution of secondary phases. The distributions of Mn, Cu, Ni, Zn, Co, and Sr do not appear to have been significantly affected during this process.It is apparent that seawater must have experienced significant Eh lowering during this interaction; however, the occurrence of hematite–magnetite and absence of sulphide in this particular environment requires that seawater was either highly depleted in total sulfur or experienced a significant rise in pH.

Dynamic Simulation of an Organic Rankine Cycle (ORC) System Driven by Exhaust

2015 ◽  
Vol 738-739 ◽  
pp. 986-990
Author(s):  
Zhi Gang Wang ◽  
Jia Guang Cheng ◽  
Yan Wang ◽  
Qiang Shen
Keyword(s):  
Low Temperature ◽  
Control Strategy ◽  
Fossil Fuels ◽  
Moving Boundary ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Energy Crisis ◽  
Transient Phenomena ◽  
Simulation Results ◽  
Boundary Model

Organic Rankine Cycle (ORC) is one of the most promising technologies for low-temperature energy conversion. In recent years, it has gotten more attention due to the energy crisis and environmental problems caused by the combustion of fossil fuels. In this paper, a moving boundary model is introduced to describe the transient phenomena of evaporator and condenser, which are the important components of ORC. The simulation results are given to illustrate the efficiency and feasibility of the proposed control strategy.

The penetration and ricochet of ogive-nosed rigid projectiles obliquely impacting metallic targets

2021 ◽  
pp. 204141962110377
Author(s):  
Yaniv Vayig ◽  
Zvi Rosenberg
Keyword(s):  
Experimental Data ◽  
Numerical Simulations ◽  
Dynamic Pressure ◽  
Oblique Impacts ◽  
Simulation Results ◽  
The Impact ◽  
Penetration Depths ◽  
Resistance To Penetration ◽  
Good Agreement

A large number of 3D numerical simulations were performed in order to follow the trajectory changes of rigid CRH3 ogive-nosed projectiles, impacting semi-infinite metallic targets at various obliquities. These trajectory changes are shown to be related to the threshold ricochet angles of the projectile/target pairs. These threshold angles are the impact obliquities where the projectiles end up moving in a path parallel to the target’s face. They were found to depend on a non-dimensional entity which is equal to the ratio between the target’s resistance to penetration and the dynamic pressure exerted by the projectile upon impact. Good agreement was obtained by comparing simulation results for these trajectory changes with experimental data from several published works. In addition, numerically-based relations were derived for the penetration depths of these ogive-nosed projectiles at oblique impacts, which are shown to agree with the simulation results.

scholarly journals Exotic garnet–clinopyroxene–K-feldspar granulites from the Chepelare shear zone, Central Rhodope massif, Bulgaria: implications for high-pressure granulite facies metamorphism

2019 ◽  
Vol 48 (3) ◽  
pp. 49-63
Author(s):  
Milena Georgirva ◽  
Tzvetomila Vladinova
Keyword(s):  
Shear Zone ◽  
Thick Layer ◽  
Granulite Facies ◽  
Mineral Association ◽  
Granulite Facies Metamorphism ◽  
Fine Grain ◽  
Fluid Infiltration ◽  
High Pressure Granulite ◽  
The Matrix ◽  
Homogeneous Matrix

Garnet–clinopyroxene–K-feldspar granulite occurs as a thick layer or boudin within the variegated rocks of the Chepelare shear zone in the Central Rhodope massif, Bulgaria. It consists of several domains: mesocratic homogeneous matrix (clinopyroxene–plagioclase–K-feldspar–quartz ± amphibole), porphyroblastic garnet, K-feldspar and clinopyroxene, and strongly foliated fine-grain bands (chloritized biotite–chlorite–prehnite–albite ± epidote). The origin and nature of the matrix mineral association is still unclear. The peak porphyroblast association forms at the expense of plagioclase from the matrix at higher pressure. The fine-grain deformation zones channel the lattermost fluid infiltration. The clinopyroxene-garnet and Zr-in-titanite thermometry give temperatures higher than 790–860 ºC at 2 GPa and, with thermodynamic modeling, suggests crystallization at ~1.8–2.1 GPa and temperature of ~850 ºC in HP granulite field for the porphyroblast granulite association.

scholarly journals Characterization and Corrosion Resistance Behavior of Shape Memory Stainless Steel Developed by Alternate Routes

Metals ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 13
Author(s):  
David Dias ◽  
Sandra Nakamatsu ◽  
Carlos Alberto Della Rovere ◽  
Jorge Otubo ◽  
Neide Aparecida Mariano
Keyword(s):  
Corrosion Resistance ◽  
Shape Memory ◽  
Dendritic Structure ◽  
Microstructural Characterization ◽  
Rolling Process ◽  
Chloride Ions ◽  
Secondary Phases ◽  
Electrochemical Tests ◽  
The Matrix ◽  
Routing Methods

The microstructural characterization and corrosion resistance behavior of Fe-Mn-Si-Cr-Ni alloy with shape memory effect was studied under different mechanical processing conditions and heat treatments, which were produced using conventional casting and routing methods to reduce costs and make production viable. Microstructural characterization was performed with electron microscopy and x-ray diffraction techniques, electrochemical tests with polarization, and thermogravimetry techniques. The cast condition presented a dendritic structure and the presence of the secondary phases: ferrite-δ and Chi-X phase. The heat treatment eliminated phases, reincorporated elements in the matrix, and increased the austenitic grain. After the hot rolling process, the alloy exhibited a refined microstructure with recrystallized austenitic grains. The heat-treated condition presented better oxidation resistance than the other conditions, while the hot-rolled condition showed repassivation of the pits, raising them to higher levels. All conditions presented low corrosion resistance in environments containing chloride ions.

Advanced Fiber Reinforced Self-Healing Ceramics for Middle Range Temperature

2019 ◽  
Vol 810 ◽  
pp. 119-124
Author(s):  
Wataru Nakao ◽  
Taira Hayakawa ◽  
Tesuro Yanaseko ◽  
Shingo Ozaki
Keyword(s):  
Low Temperature ◽  
Turbine Blade ◽  
The Self ◽  
Self Healing ◽  
Fiber Reinforced ◽  
Low Pressure Turbine ◽  
Middle Range ◽  
The Matrix ◽  
Healing Agent ◽  
Technical Issues

The availability of TiC healing agent has been evaluated in low temperature self-healing behavior of Al2O3 based self-healing ceramics. For this purpose, some technical issues to actualize the advanced fiber-reinforced self-healing ceramics containing TiC based interlayer as healing agent were discussed. Especially, the mechanical matching between the matrix and the interlayer was focused. Moreover, the self-healing behavior of the advanced shFRC containing the optimized TiC based healing agent was investigated. As a result, 30 vol% TiC-70 vol% Al2O3 interlayer was confirmed to be the optimized healing agent in the self-healing ceramics, and the self-healing ceramics was found to enable to attain the perfect healing at 600°C within 10 min. And we succeeded in prototype production of fiber-reinforced self-healing ceramics for low pressure turbine blade.

scholarly journals Allanite Geochemical Response to Hydrothermal Alteration by Alkaline, Low-Temperature Fluids

Minerals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 392 ◽  
Author(s):  
Katarzyna Gros ◽  
Ewa Słaby ◽  
Petras Jokubauskas ◽  
Jiří Sláma ◽  
Gabriela Kozub-Budzyń
Keyword(s):  
Rare Earth ◽  
Low Temperature ◽  
Rare Earth Elements ◽  
Geochemical Evolution ◽  
Additional Component ◽  
Second Stage ◽  
Ce Anomaly ◽  
Hydrothermal Processes ◽  
Fluid Infiltration ◽  
Two Stages

Allanite is one of the main rare earth elements (REE)-rich accessory minerals in composite dykes from the granitoid pluton of Karkonosze. These dykes differ in composition from the bulk of the pluton by elevated rare earth elements (REE), Y, Zr, and alkali contents, suggesting contribution of an additional component. Allanite exhibits complex alteration textures, which can be divided into two stages. The first stage is represented by allanite mantles, formed by fluid infiltration into previously crystallized magmatic allanite. These zones have low totals, are Ca-, Al-, Mg-, and light REE (LREE)-depleted, and Y-, heavy REE (HREE)-, Th-, Ti-, and alkali-enriched. The fractionation between LREE and HREE was caused by different mobility of complexes formed by these elements in aqueous fluids. The second stage includes recrystallized LREE-poor, Y-HREE-rich allanite with variable Ca, Al, Mg, and REE-fluorocarbonates. The alteration products from both stages demonstrate higher Fe3+/(Fe2+ + Fe3+) ratios and a negative Ce anomaly. These features point to the alkaline, low-temperature, and oxidized nature of the fluids. The differences in mobility and solubility of respective ligands show that the fluids from the first stage may have been dominated by Cl, whereas those of the second stage may have been dominated by F and CO2 (and PO4 in case of one sample). The inferred chemistry of the fluids resembles the overall geochemical signature of the composite dykes, indicating a major contribution of the hydrothermal processes to their geochemical evolution.

Evaluation on Microstructure of Aluminum Alloys Dedicated to Plasma Etcher

2011 ◽  
Vol 689 ◽  
pp. 343-349
Author(s):  
Zhi Hui Zhang ◽  
Shu Feng Liu ◽  
Ze Ming Sun ◽  
Xiao Dong Yan
Keyword(s):  
Aluminum Alloy ◽  
Aluminum Alloys ◽  
Anodic Oxidation ◽  
Scientific Basis ◽  
Secondary Phases ◽  
6061 Aluminum Alloy ◽  
Close Relationship ◽  
The Matrix ◽  
Hole Defects

The relationship between microstructure and anodic oxidation film on 6061 aluminum alloy dedicated to plasma etcher were mainly studied by OM, SEM and TEM. The results show that the quality of anodic oxidation film has close relationship with the microstructure of materials, the distribution of element and the morphology of secondary phases. The microstructure of foreign 6061 aluminum alloy is uniform, and there are not obviously segregation and cavity. Two kinds of secondary phases disperse over the grain, one is rich-Fe phase, and the other is Mg2Si. Certainly there are also few secondary phases distributing along the grain boundary. The sizes of all secondary phases are almost below 5mm. The size of rich-Fe phases in homemade aluminum alloys are about from 2mm to 15mm, these big-size phases will bring pin-hole defects, which form some channels sending F+ etc. into the matrix of aluminum alloy, then not only the equipment will be destroyed at last, but also products will be polluted. The evaluation on microstructure of aluminum alloy will provide scientific basis for nationalization of plasma etcher.

An Investigation of a Nitrogen Enhanced Steel Processed by Explosive Powder Compaction

2005 ◽  
Vol 475-479 ◽  
pp. 265-268
Author(s):  
Can Dong Zhou ◽  
Jun Fei Fan ◽  
Hai Rong Le ◽  
Guo Chang Jiang ◽  
Jing Guo Zhang
Keyword(s):  
Processing Parameters ◽  
Powder Compaction ◽  
Mechanical Tests ◽  
High Nitrogen Steel ◽  
High Nitrogen ◽  
Final Density ◽  
Nitrogen Steel ◽  
The Matrix ◽  
Definition Of ◽  
Radial Cracks

A structural steel, 35CrMoV steel, has been attempted firstly by explosive powder compaction followed by sintering (EPC-sintering). The nitrogen content of the steel was 0.15wt%, which was accordant with the definition of high nitrogen steel (HNS). The final density of the EPC-sintering steel was only about 6.9g/cm3, which indicated that the processing parameters must be modulated further. In the sample of this steel, some radial cracks were found around the center of the cross-section of the steel, resulting in no mechanical tests carrying out. Observing the majority of the rim region of the sample of this steel, the microstructures were very tight, suggesting that it was possible and successful to manufacture HNS through EPC-sintering. The characteristics of the EPC-sintering high nitrogen 35CrMoV steel were that the cementites in the pearlites were found to be extremely fine. There were many (Cr,Mo)23(C,N)6 carbonitrides precipitates in the matrix. Some precipitates were round and others were needle-like. Some were distributing orderly in matrix and crossing over the dislocations. The dislocation density in the EPC-sintering steel remained high.

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