Microstructure, Stiffness and Corrosion of Bare and Phosphated Specimens Made by Sintering of Structured Iron-Iron Oxide Spheres

2020 ◽  
Vol 405 ◽  
pp. 411-416
Author(s):  
Miriam Kupková ◽  
Martin Kupka ◽  
Renáta Oriňáková ◽  
Radka Gorejová
Keyword(s):  
Iron Oxide ◽  
Iron Oxides ◽  
Metallic Iron ◽  
Galvanic Corrosion ◽  
Iron Phosphate ◽  
Reduction Reaction ◽  
Diffusion Control ◽  
Iron Oxide Particles ◽  
Flow Through ◽  
Iron Iron

Granulated iron oxide particles were incompletely reduced to structured particles comprised metallic iron and residual iron oxides. Structured particles were pressed into prismatic compacts and sintered. Some of sintered specimens were subsequently phosphatized and calcined. Specimens with an iron phosphate coating were found stiffer than specimens without coating. In Hanks' solution, a galvanic corrosion was induced by more noble iron oxides coupled to a less noble metallic iron. This could explain higher corrosion potentials and higher rates of iron dissolution in comparison with a pure iron. The coating of specimens with iron phosphates shifted corrosion potentials towards more negative values and slowed down the dissolution of iron. This was most likely caused by a reduction in oxygen flow through the coating to iron-oxide cathodes, which has enhanced the influence of diffusion control on the kinetics of reduction reaction.

scholarly journals Synthesis, Characterization and Adsorptive Performances of a Composite Material Based on Carbon and Iron Oxide Particles

2019 ◽  
Vol 20 (7) ◽  
pp. 1609 ◽  
Author(s):  
Vasile Mînzatu ◽  
Corneliu-Mircea Davidescu ◽  
Petru Negrea ◽  
Mihaela Ciopec ◽  
Cornelia Muntean ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Composite Material ◽  
Iron Oxide ◽  
Iron Oxides ◽  
Arsenic Removal ◽  
Soluble Starch ◽  
Reaction Mass ◽  
Iron Chloride ◽  
Maximum Adsorption Capacity ◽  
Iron Oxide Particles

The aim of this paper was to produce a new composite material based on carbon and iron oxides, starting from soluble starch and ferric chloride. The composite material was synthesized by simple thermal decomposition of a reaction mass obtained from starch and iron chloride, in an inert atmosphere. Starch used as a carbon source also efficiently stabilizes the iron oxides particles obtained during the thermal decomposition. The reaction mass used for the thermal decomposition was obtained by simultaneously mixing the carbon and iron oxide precursors, without addition of any precipitation agent. The proper composite material can be obtained by rigorously adhering to the stirring time, temperature, and water quantity used during the preparation of the reaction mass, as well as the thermal regime and the controlled atmosphere used during the thermal decomposition. Synthesized materials were characterized using thermogravimetric analysis, X-Ray Diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infra-red spectroscopy (FT-IR). The performances of the obtained material were highlighted by studying their adsorbent properties and by determining the maximum adsorption capacity for arsenic removal from aqueous solutions.

Plasma production of metallic nanoparticles

1992 ◽  
Vol 7 (8) ◽  
pp. 2107-2113 ◽  
Author(s):  
ChinHao Chou ◽  
Jonathan Phillips
Keyword(s):  
Iron Oxide ◽  
Metallic Iron ◽  
Metallic Nanoparticles ◽  
Composition Analysis ◽  
Iron Oxide Particles ◽  
Injection Point ◽  
Argon Plasmas ◽  
Transmission Electron ◽  
Microwave Power Source ◽  
Two Parameters

Metallic iron and iron oxide particles were produced by injecting ferrocene into the afterglow region of a low pressure, low power, plasma generated using a microwave power source. This was done as part of an effort to explore the feasibility of using flow type microwave plasmas for the production of metal nanoparticles. It was found that two parameters had the largest impact on the particles: injection point and plasma composition. Analysis done using Mössbauer effect spectroscopy, transmission electron microscopy, and x-ray diffraction indicated that low yields of small particles (ca. 10 nm) resulted from injection into the afterglow region. Much higher yields of large particles (ca. 50 nm) formed if the ferrocene was injected through the coupler. In hydrogen plasmas the particles that were produced were metallic iron, whereas in oxygen and argon plasmas the particles were iron oxide. In all cases significant amounts of graphitic carbon formed around the metal particles.

Iron oxide/oxyhydroxide decorated graphene oxides for oxygen reduction reaction catalysis: a comparison study

RSC Advances ◽  
2016 ◽  
Vol 6 (35) ◽  
pp. 29848-29854 ◽  
Author(s):  
Xiangqian Liu ◽  
Weihua Hu
Keyword(s):  
Graphene Oxide ◽  
Iron Oxide ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Iron Oxides ◽  
Reduction Reaction ◽  
Comparison Study ◽  
Graphene Oxides

Four iron/graphene composites with iron oxides or oxyhydroxides supported on graphene oxide were synthesized and their ORR activities were systematically investigated and compared.

Iron oxide decorated N-doped carbon derived from poly(ferrocene-urethane) interconnects for the oxygen reduction reaction

2018 ◽  
Vol 42 (19) ◽  
pp. 15629-15638 ◽  
Author(s):  
Viji Premkumar ◽  
Naveen Chandrasekaran ◽  
Kanagaraj Madasamy ◽  
Murugavel Kathiresan ◽  
Pandiyaraj Kanagavalli ◽  
...  
Keyword(s):  
Iron Oxide ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Reduction Reaction ◽  
Iron Oxide Particles ◽  
Nitrogen Doped ◽  
Oxide Particles ◽  
Nitrogen Doped Carbon ◽  
Mixed Iron Oxide

We report the synthesis of mixed iron oxide particles decorated on nitrogen-doped carbon by forming covalent polyurethane linkages between ferrocene and phloroglucinol.

scholarly journals INVESTIGATION OF SURFACES OF NOVEL IRON OXIDES WITH GRAIN AND GRAIN BOUNDARY

2018 ◽  
Vol 56 (1A) ◽  
pp. 226
Author(s):  
Nguyet Viet Long
Keyword(s):  
Heat Treatment ◽  
Iron Oxide ◽  
Grain Boundary ◽  
Iron Oxides ◽  
Particle System ◽  
Oxide Particle ◽  
Oxide System ◽  
Iron Oxide Particle ◽  
Iron Oxide Particles ◽  
Oxide Particles

Hierarchical nano/microscale α-Fe2O3 iron oxide particle system was prepared by an improved and modified polyol method with the use of NaBH4 agent with high heat treatment at 900 °C in air. Here, α-Fe2O3 iron oxide particles with different shapes were analyzed. The morphologies of the surfaces of α-Fe2O3 iron oxide particles show the oxide structures with the different nano/microscale ranges of grain sizes. In this research, we have found that grain and grain boundary growth limits can be determined in α-Fe2O3 iron oxide structure. This leads to the possibility of producing new iron oxide structures with distribution of desirable size grain and grain boundary. With α-Fe2O3 structure obtained, the magnetic properties of the α-Fe2O3 iron oxide system are different from those of previously reported studies. in national and international studies.Keywords: Iron iron oxides, α-Fe2O3, chemical polyol methods, heat treatment.

scholarly journals Accelerated dissolution of iron oxides in ice

2012 ◽  
Vol 12 (22) ◽  
pp. 11125-11133 ◽  
Author(s):  
D. Jeong ◽  
K. Kim ◽  
W. Choi
Keyword(s):  
Iron Oxide ◽  
Grain Boundary ◽  
Surface Area ◽  
Iron Oxides ◽  
Boundary Region ◽  
Iron Oxide Particles ◽  
Iron Dissolution ◽  
Dissolved Iron ◽  
Enhanced Dissolution ◽  
Oxide Particles

Abstract. Iron dissolution from mineral dusts and soil particles is vital as a source of bioavailable iron in various environmental media. In this work, the dissolution of iron oxide particles trapped in ice was investigated as a new pathway of iron supply. The dissolution experiments were carried out in the absence and presence of various organic complexing ligands under dark condition. In acidic pH conditions (pH 2, 3, and 4), the dissolution of iron oxides was greatly enhanced in the ice phase compared to that in water. The dissolved iron was mainly in the ferric form, which indicates that the dissolution is not a reductive process. The extent of dissolved iron was greatly affected by the kind of organic complexing ligands and the surface area of iron oxides. The iron dissolution was most pronounced with high surface area iron oxides and in the presence of strong iron binding ligands. The enhanced dissolution of iron oxides in ice is mainly ascribed to the "freeze concentration effect", which concentrates iron oxide particles, organic ligands, and protons in the liquid like ice grain boundary region and accelerates the dissolution of iron oxides. The ice-enhanced dissolution effect gradually decreased when decreasing the freezing temperature from −10 to −196 °C, which implies that the presence and formation of the liquid-like ice grain boundary region play a critical role. The proposed phenomenon of enhanced dissolution of iron oxides in ice may provide a new pathway of bioavailable iron production. The frozen atmospheric ice with iron-containing dust particles in the upper atmosphere thaws upon descending and may provide bioavailable iron upon deposition onto the ocean surface.

scholarly journals Accelerated dissolution of iron oxides in ice

2012 ◽  
Vol 12 (8) ◽  
pp. 20113-20134 ◽  
Author(s):  
D. Jeong ◽  
K. Kim ◽  
W. Choi
Keyword(s):  
Iron Oxide ◽  
Grain Boundary ◽  
Iron Oxides ◽  
Boundary Region ◽  
Dust Particles ◽  
Iron Oxide Particles ◽  
Iron Dissolution ◽  
Dissolved Iron ◽  
Enhanced Dissolution ◽  
Oxide Particles

Abstract. Iron dissolution from mineral dusts and soil particles is vital as a source of bioavailable iron in various environmental media. In this work, the dissolution of iron oxide particles trapped in ice was investigated as a~new pathway of iron supply. The dissolution experiments were carried out in the absence and presence of various organic complexing ligands under dark condition. In acidic pH conditions (pH 2, 3, and 4), the dissolution of iron oxides was greatly enhanced in the ice phase compared to that in water. The dissolved iron was mainly in the ferric form, which indicates that the dissolution is not a reductive process. The extent of dissolved iron was greatly affected by the kind of organic complexing ligands and the type of iron oxides. The iron dissolution was most pronounced with high surface area iron oxides and in the presence of strong iron binding ligands. The enhanced dissolution of iron oxides in ice is mainly ascribed to the "freeze concentration effect", which concentrates iron oxide particles, organic ligands, and protons in the liquid-like ice grain boundary region and accelerates the dissolution of iron oxides. The ice-enhanced dissolution effect gradually decreased when decreasing the freezing temperature from −10 °C to −196 °C, which implies that the presence and formation of the liquid-like ice grain boundary region play a critical role. The proposed phenomenon of enhanced dissolution of iron oxides in ice may provide a new pathway of bioavailable iron production. The frozen atmospheric ice with iron-containing dust particles in the upper atmosphere thaws upon descending and may provide bioavailable iron upon deposition onto the ocean surface.

Microscopic behavior and metallic iron morphology from reduction of iron oxide by CO/H2in a fluidized bed

2018 ◽  
Vol 51 (6) ◽  
pp. 1641-1651 ◽  
Author(s):  
Feng Lu ◽  
Liangying Wen ◽  
Hong Zhong ◽  
Jian Xu ◽  
Shengfu Zhang ◽  
...  
Keyword(s):  
Iron Oxide ◽  
Fluidized Bed ◽  
Metallic Iron ◽  
Density Functional ◽  
Reduction Rate ◽  
Iron Ion ◽  
Ion Diffusion ◽  
Iron Oxide Particles ◽  
Reduction Of Iron ◽  
Oxide Particles

Fe2O3particles reduced by CO or H2exhibit different metallic iron morphology. To determine the mechanism of metallic iron formation during the reduction of iron oxide particles by CO/H2in a fluidized bed, an innovative multiscale method was used. This method was validated by experimental results. Density functional theory calculations demonstrate that the CO molecule has a strong stretching effect on the iron ion of wustite in the vertical direction, but the H2molecule has no directional force on the structure of wustite. The energy released from CO reduction is used to overcome the energy barrier of iron ion diffusion. However, H2addition will hinder iron ion diffusion by consuming energy. By analysis of the thermogravimetric curves of Fe2O3reduction, it was found that the adsorption ability of H2on the surface of FeO is weaker than that of CO. However, the reduction rate is higher under H2atmosphere, according to Langmuir adsorption isotherm theory. The morphology of metallic iron during the reduction of iron oxide particles by CO/H2was observed with a scanning electron microscope equipped with an energy dispersive X-ray spectroscopy detector

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