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Hernandez L.G.,Area Academica de Ciencias de la Tierra y Materiales | Ramirez M.V.,Area Academica de Ciencias de la Tierra y Materiales | Cruz V.R.,Area Academica de Ciencias de la Tierra y Materiales | Ramirez A.C.,ESIQIE
Materials Science Forum | Year: 2011

A three dimensions mathematical modeling was developed with COMSOL 3.2 software of an electroremediation cell. The Navier Stokes and Darcy equations were used to model the behavior of the electrolyte and the sand, respectively. The mass balance for hydrogen ion was carried out with Nernst-Planck equation for the anode and soil regions. The main factors that contribute to the hydrogen ion balance were the diffusive flux and electric migration. The mathematical modeling was validated with an experimental arrangement consisted in an electroremediation cell which contains sand as porous medium and water as electrolyte. A potential of 20 V was applied for 24 hours and the pH was measured continuously. The results of the model are in good agreement with those obtained experimentally. © (2011) Trans Tech Publications, Switzerland.


Samperio-Gomez I.L.,Area Academica de Ciencias de la Tierra y Materiales | Cortes-Escobedo C.A.,Research Center e Innovacion Tecnologica del Cda | Bolarin-Miro A.M.,Area Academica de Ciencias de la Tierra y Materiales | Sanchez-De Jesus F.,Area Academica de Ciencias de la Tierra y Materiales
Advanced Materials Research | Year: 2014

Several methods for processing tubular anodes for solid oxide fuel cells have been developed, but many of them are expensive and sophisticated, therefore, there is a great interest in researching the use of a simple process to produce them. In this paper, the results of using slip casting for processing minitubes of NiO-8YSZ with the dimensions of 100x5x1 mm are presented.This is a versatile method for obtaining complex geometries with a suitable surface finish and dimensional precision at low cost compared with ceramic processing which uses high energy consumption and/or has high startup costs. In order to carry out this study, an aqueous slurry of an oxide mixture of NiO-8YSZ with poly-etilenglycol as a dispersant agent was used. The modification of the ratio of water:ceramic powders, the composition NiO:x8YSZ (30, 50 and 70 in wt.) and the casting time (3 to 30 min) were also applied. The minitubes obtained were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and spectroscopy of dispersive energy (EDS). The results show that slip casting is an appropriate method to obtain NiO-8YSZ minitubes. Minitubes of varying composition (30, 50 and 70% in wt. of NiO) with dimensions of 100x5x1 mm were obtained showing an excellent porosity (higher than 96% in v/v) and a homogeneous distribution of NiO and 8YSZ particles. XRD analysis confirms the presence of starting oxides before and after the casting process. © (2014) Trans Tech Publications, Switzerland.


Sanchez-De Jesus F.,Area Academica de Ciencias de la Tierra y Materiales | Bolarin-Miro A.M.,Area Academica de Ciencias de la Tierra y Materiales | Torres-Villasenor G.,National Autonomous University of Mexico | Cortes-Escobedo C.A.,Research Center e Innovacion Tecnologica Del | Betancourt-Cantera J.A.,Area Academica de Ciencias de la Tierra y Materiales
Journal of Materials Science: Materials in Medicine | Year: 2010

We report on an alternative route for the synthesis of crystalline Co-28Cr-6Mo alloy, which could be used for surgical implants. Co, Cr and Mo elemental powders, mixed in an adequate weight relation according to ISO Standard 58342-4 (ISO, 1996), were used for the mechanical alloying (MA) of nano-structured Co-alloy. The process was carried out at room temperature in a shaker mixer mill using hardened steel balls and vials as milling media, with a 1:8 ball:powder weight ratio. Crystalline structure characterization of milled powders was carried out by X-ray diffraction in order to analyze the phase transformations as a function of milling time. The aim of this work was to evaluate the alloying mechanism involved in the mechanical alloying of Co-28Cr-6Mo alloy. The evolution of the phase transformations with milling time is reported for each mixture. Results showed that the resultant alloy is a Co-alpha solid solution, successfully obtained by mechanical alloying after a total of 10 h of milling time: first Cr and Mo are mechanically prealloyed for 7 h, and then Co is mixed in for 3 h. In addition, different methods of premixing were studied. The particle size of the powders is reduced with increasing milling time, reaching about 5 μm at 10 h; a longer time promotes the formation of aggregates. The morphology and crystal structure of milled powders as a function of milling time were analyzed by scanning electron microscopy and XR diffraction. © 2010 Springer Science+Business Media, LLC.


Palomino R.L.,Area Academica de Ciencias de la Tierra y Materiales | Bolarin Miro A.M.,Area Academica de Ciencias de la Tierra y Materiales | Tenorio F.N.,Area Academica de Ciencias de la Tierra y Materiales | Sanchez De Jesus F.,Area Academica de Ciencias de la Tierra y Materiales | And 2 more authors.
Ultrasonics Sonochemistry | Year: 2016

We present the synthesis of M-type strontium hexaferrite by sonochemistry and annealing. The effects of the sonication time and thermal energy on the crystal structure and magnetic properties of the obtained powders are presented. Strontium hexagonal ferrite (SrFe12O19) was successfully prepared by the ultrasonic cavitation (sonochemistry) of a complexed polyol solution of metallic acetates and diethylene glycol. The obtained materials were subsequently annealed at temperatures from 300 to 900 °C. X-ray diffraction analysis shows that the sonochemical process yields an amorphous phase containing Fe3+, Fe2+ and Sr2+ ions. This amorphous phase transforms into an intermediate phase of maghemite (γ-Fe2O3) at 300 °C. At 500 °C, the intermediate species is converted to hematite (α-Fe2O3) by a topotactic transition. The final product of strontium hexaferrite (SrFe12O19) is generated at 800 °C. The obtained strontium hexaferrite shows a magnetization of 62.3 emu/g, which is consistent with pure hexaferrite obtained by other methods, and a coercivity of 6.25 kOe, which is higher than expected for this hexaferrite. The powder morphology is composed of aggregates of rounded particles with an average particle size of 60 nm. © 2015 Elsevier B.V.


Tenorio Gonzalez F.N.,Area Academica de Ciencias de la Tierra y Materiales | Bolarin Miro A.M.,Area Academica de Ciencias de la Tierra y Materiales | Sanchez De Jesus F.,Area Academica de Ciencias de la Tierra y Materiales | Cortes Escobedo C.A.,Research Center e Innovacion Tecnologica Del | Ammar S.,University Paris Diderot
Journal of Magnetism and Magnetic Materials | Year: 2016

The synthesis mechanism of nanostructured M-type strontium hexaferrite SrFe12O19 with high coercivity (5.7 kOe) obtained by a polyol process and annealing is proposed. The results show that the hexaferrite is synthesized through the formation of a complex with diethylene glycol during the hydrolysis and solvation stage, followed by the condensation of magnetite and strontium oxide. The results of the monitoring of the process by X-ray diffraction (XRD) of synthesized powders, magnetization hysteresis loops and micromorphology are presented and discussed. The proposed mechanism suggests the intermediate formation of the magnetite phase, which shows coercivity near zero at room temperature and confirms the nanoscale of the particles. Results of thermogravimetric and differential thermal analysis indicate that this phase is followed by the formation of the hematite phase after a heat treatment up to 543 °C in an oxidizing atmosphere. Finally, the hexagonal phase is obtained after application of annealing at 836 °C through the reaction between hematite and strontium oxide. © 2016 Elsevier B.V.


Bolarin-Miro A.M.,Area Academica de Ciencias de la Tierra y Materiales | Jesus F.S.-D.,Area Academica de Ciencias de la Tierra y Materiales | Torres-Villasenor G.,National Autonomous University of Mexico | Cortes-Escobedo C.A.,Research Center e Innovacion Tecnologica Del | And 2 more authors.
Journal of Non-Crystalline Solids | Year: 2011

Structural transformations and the amorphization of cobalt base alloy particles are possible when a powder mixture of Co and Cr-Mo is subjected to the mechanical alloying (MA) process. Elemental powders mixed in adequate weight ratios were used as precursors. The process was carried out at room temperature in a shaker mixer mill using vials and balls of hardened steel as milling media, with a ball:powder weight ratio of 8:1. The characterization of the crystalline structure of milled powders was carried out by means of X-ray diffraction to analyze the phase transformations as a function of milling time. The aim of this work was to demonstrate that MA can induce the amorphization of Co-Cr-Mo alloy. The evolution of the phase transformation during milling time is reported. The results showed that it is possible to produce a partial solid solution at room temperature of elemental metallic powders Co70Cr30 and Co90Mo10 by mechanical alloying. Using specific experimental conditions, it is also possible to obtain an amorphous phase in a composition Co60Cr30Mo10; first, Cr and Mo were mechanically prealloyed for 9 h to obtain a Cr80Mo20 solid solution, and Co was then added and milled in over 14 h. © 2011 Elsevier B.V. All rights reserved.


Edgar Cardoso E.,Area Academica de Ciencias de la Tierra y Materiales | Arenas Flores A.,Area Academica de Ciencias de la Tierra y Materiales | Garcia F.L.,Area Academica de Ciencias de la Tierra y Materiales
Advanced Materials Research | Year: 2014

The treatment with mechanical vibrations during the solidification process promote microstructural changes in metallic alloys, in order to have a better understanding on this matter mechanical vibration were applied to an aluminum alloy A356, while teeming in order to evaluate the morphological changes on αAl primary phase in the solidification process. Two routes were analyzed, a cooling slope and a rotational mould. This paper shows the results of quantify the effect of mechanical vibration and the specific characteristic of casting to obtain a spherical morphology on the αAl primary, that allow to obtain thixoformable raw material. © (2014) Trans Tech Publications, Switzerland.


Betancourt-Cantera J.A.,Area Academica de Ciencias de la Tierra y Materiales | Sanchez-De Jesus F.,Area Academica de Ciencias de la Tierra y Materiales | Torres-Villasenor G.,National Autonomous University of Mexico | Bolarin-Miro A.M.,Area Academica de Ciencias de la Tierra y Materiales | Cortes-Escobedo C.A.,Research Center e Innovacion Tecnologica Del
Journal of Alloys and Compounds | Year: 2012

Mechanical alloying, MA, has been successfully used to extend the limits of solid solubility in many commercially important metallic systems. The aim of this work is to demonstrate that MA modifies the solid solubility of the Co-Cr system. Co and Cr elemental powders were used as precursors and mixed in an adequate weight ratio to obtain Co100-xCrx (0 ≤ x ≤ 100, Δx = 10) to study the effect of mechanical processing in the solubility of the Co-Cr system. Processing was carried out at room temperature in a shaker mixer mill using vials and balls of hardened steel as milling media with a ball:powder weight ratio of 10:1. Crystalline structure characterization of the milled powders was conducted using X-ray diffraction, and phase transformations as a function of composition were analyzed. Thermal analysis confirmed structural changes occurred in the mechanically alloyed powders. The evolution of the phase transformations with composition is reported for each composition. The results showed that after high energy ball milling for 7 h, the solid solubility between Co and Cr could be evidently extended, despite the low solid solubility at the equilibrium conditions of this system. Additionally, the micrographs of the milled powders showed that increasing composition of chromium changes the shape and size of the particles while simultaneously reducing their agglomeration; this effect is possibly attributed to the brittleness of elemental chrome. © 2012 Elsevier B.V. All rights reserved.


Betancourt-Cantera J.A.,Area Academica de Ciencias de la Tierra y Materiales | Sanchez-De Jesus F.,Area Academica de Ciencias de la Tierra y Materiales | Bolarin-Miro A.M.,Area Academica de Ciencias de la Tierra y Materiales | Betancourt I.,National Autonomous University of Mexico | Torres-Villasenor G.,National Autonomous University of Mexico
Journal of Magnetism and Magnetic Materials | Year: 2014

In this paper, a systematic study on the structural and magnetic properties of Co100-xCrx alloys (0


PubMed | National Polytechnic Institute of Mexico, Area Academica de Ciencias de la Tierra y Materiales and University Paris Diderot
Type: | Journal: Ultrasonics sonochemistry | Year: 2015

We present the synthesis of M-type strontium hexaferrite by sonochemistry and annealing. The effects of the sonication time and thermal energy on the crystal structure and magnetic properties of the obtained powders are presented. Strontium hexagonal ferrite (SrFe12O19) was successfully prepared by the ultrasonic cavitation (sonochemistry) of a complexed polyol solution of metallic acetates and diethylene glycol. The obtained materials were subsequently annealed at temperatures from 300 to 900 C. X-ray diffraction analysis shows that the sonochemical process yields an amorphous phase containing Fe(3+), Fe(2+) and Sr(2+) ions. This amorphous phase transforms into an intermediate phase of maghemite (-Fe2O3) at 300 C. At 500 C, the intermediate species is converted to hematite (-Fe2O3) by a topotactic transition. The final product of strontium hexaferrite (SrFe12O19) is generated at 800 C. The obtained strontium hexaferrite shows a magnetization of 62.3 emu/g, which is consistent with pure hexaferrite obtained by other methods, and a coercivity of 6.25 kOe, which is higher than expected for this hexaferrite. The powder morphology is composed of aggregates of rounded particles with an average particle size of 60 nm.

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