Personne :
Darvishi Alamdari, Houshang

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Darvishi Alamdari
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Houshang
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Université Laval. Département de génie des mines, de la métallurgie et des matériaux
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ncf11847835
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Voici les éléments 1 - 4 sur 4
  • Publication
    Accès libre
    Electrochemical corrosion behavior of Fe3Al/TiC and Fe3Al-Cr/TiC coatings prepared by HVOF in NaCl solution
    (MDPI, 2019-04-13) Ahledel, Najmeh; Schulz, Robert; Hermawan, Hendra; Gariepy, Mario; Darvishi Alamdari, Houshang
    Adding TiC particles into iron aluminide coatings has been found to improve its wear resistance, but its corrosion behavior is less known. In this study, the corrosion behavior of Fe3Al/TiC and Fe3Al-Cr/TiC composite coatings, prepared by high velocity oxy fuel (HVOF) spraying, was studied in 3.5 wt. % NaCl solution by means of electrochemical techniques and surface analysis. Results revealed that adding TiC particles into Fe3Al matrix to improve the wear resistance does not deteriorate the corrosion behavior of Fe3Al coating. It was also showed that addition of chromium to Fe3Al/TiC composite provides a more protective layer.
  • Publication
    Accès libre
    Sensitivity of carbon anode baking model outputs to kinetic parameters describing pitch pyrolysis
    (American Chemical Society, 2013-02-20) Gosselin, Louis; Grégoire, François; Darvishi Alamdari, Houshang
    Carbon anode blocks, used in aluminum electrolysis cells, are usually baked in furnaces for several days, during which they release volatiles due to pitch pyrolysis. Therefore, numerical modeling of anode baking furnaces has to include some representation of pitch pyrolysis via a set of kinetic parameters. These kinetic parameters can vary with raw materials and baking parameters and are tedious to determine experimentally. In this work, we studied how the main outputs of an anode baking model are affected by the variance of the kinetic parameters. Results show that certain model outputs are not considerably influenced by changes in the kinetic parameters (e.g., spatial variation of anode porosity, maximum heating value from volatiles), while others are significantly affected (e.g., time evolution of anode porosity, time of maximum heating value of volatiles, internal pressure of anode), in particular by activation energy variability.
  • Publication
    Accès libre
    Characterization of carbon anode protected by low boron level : an attempt to understand carbon−boron inhibitor mechanism
    (American Chemical Society, 2017-07-19) Ziegler, Donald Paul; Laroche, Gaétan; Lamonier, Jean-François; Darvishi Alamdari, Houshang; Ishak, Ramzi
    Several chemical reactions occur during the electrolysis of alumina in the Hall–Héroult process resulting in a significant overconsumption of the carbon anode. Carbon oxidation with oxygen is one of these reactions. The inhibition of this reaction by the application of protective layers on the anode can be an effective technique to reduce carbon consumption. Boron impregnation was shown to suppress this reaction. In this study, very low boron content has been impregnated on the anode, and several characterization methods have been performed to understand the protection mechanism of such a low boron concentration during the oxidation reaction of anodes. An air reactivity test of boron-impregnated anodes has been performed at temperatures between 400 and 600 °C. The samples were characterized using XPS, Raman spectroscopy, XRD, XRF, porosimetry, and thermogravimetric analysis (TGA). TGA revealed that the total number of interactions between oxygen atoms and carbon active sites was reduced, decreasing the pre-exponential factor. Time-of-flight secondary ion mass spectroscopy (ToF-SIMS) has been employed as a highly sensitive surface characterization method to identify chemical forms of boron on the anode. It has been confirmed that boron blocks active sites of carbon by creating boron–carbon bonds, thus reducing the interaction of carbon active sites with oxygen.
  • Publication
    Accès libre
    Application of boron oxide as a protective surface treatment to decrease the air reactivity of carbon anodes
    (MDPI AG, 2017-03-03) Picard, Donald; Ziegler, Donald Paul; Laroche, Gaétan; Darvishi Alamdari, Houshang; Ishak, Ramzi
    The oxidation of a carbon anode with air and CO2 occurs during the electrolysis of alumina in Hall-Héroult cells, resulting in a significant overconsumption of carbon and dusting. Boron is well known to decrease the rate of this reaction for graphite. In this work, the application of boron oxide has been investigated to evaluate its inhibition effect on the air oxidation reaction, and to provide an effective protection for anodes. Different methods of impregnation coating have been explored. Impregnated anode samples were gasified under air at 525 °C according to the standard measurement methods. X-ray tomography was used to obtain the microstructural information of the samples before and after air-burning tests. The impregnated samples showed a very low oxidation reaction rate and dust generation.