evolution of an alumina magnesia self forming spinel
Roghayeh NikbakhtTarbiat Modares UniversityGreater
• In situ spinel formation of Alumina–magnesia castables was explored In situ spinel formation and the reaction is affected by the magnesia source and its grain size • Castables were prepared with different magnesia grain sizes and different formula the samples were evaluated by an assisted sintering technique mechanical strength and Magnesium aluminate (Spinel) inclusions have been observed to cause hook crack in line pipe steels. These inclusions are typically formed during liquid steel processing at the ladle metallurgy furnace (LMF) and subsequently modified by calcium to form less harmful liquid inclusions. Unfortunately spinel inclusions are still sometimes observed in
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Formation and evolution of Spinel in aluminum killed
Magnesium aluminate (Spinel) inclusions have been observed to cause hook crack in line pipe steels. These inclusions are typically formed during liquid steel processing at the ladle metallurgy furnace (LMF) and subsequently modified by calcium to form less harmful liquid inclusions. Unfortunately spinel inclusions are still sometimes observed in • In situ spinel formation of Alumina–magnesia castables was explored In situ spinel formation and the reaction is affected by the magnesia source and its grain size • Castables were prepared with different magnesia grain sizes and different formula the samples were evaluated by an assisted sintering technique mechanical strength and
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EVOLUTION OF OXYGEN ISOTOPIC COMPOSITION IN THE
EVOLUTION OF OXYGEN ISOTOPIC COMPOSITION IN THE INNER SOLAR NEBULA Alexander N. Krot 1 Ian D. Hutcheon 2 Hisayoshi Yurimoto 3 Jeffrey N. Cuzzi 4 Kevin D. McKeegan 5 Edward R. D. Scott 1 Guy Libourel 6 7 Marc Chaussidon 6 Jerome Ale´on 6 and Michael I. Petaev8 Received 2004 September 27 accepted 2004 December 17 How does the spinel formation improve the flexibility of spinel forming alumina castables at elevated temperature in Proceedings of the 59th International Conference
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(PDF) The effect of nano sized carbon black on the phase
THE EFFECT OF NANOSIZED CARBON BLACK ON THE PHASE EVOLUTION AND RHEOLOGICAL PROPERTIES OF AL2O3- SICSIO2-C CASTABLE 1 2 Mohamad Hassan Amin Mohsen Amin-Ebrahimabadi 1 Materials and Energy Research Centre(MERC) Meshkin-Dasht Road Karaj IRAN 2 Pars Refractories Co. Yazd Iran INTRODUCTION Al2O3-SiC-SiO2 composites have been widely Mar 11 2014 · Calcium hexaluminate (CA 6) was incorporated into the matrix of magnesio aluminate spinel-alumina (MA-A) via infiltration of a porous preform
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Evolution of an alumina-magnesia/self-forming spinel
This study was carried out in conjunction with the investigation reported in Part I on the microstructural characteristics of an alumina-spinel castable with several percentages of MgO content. Bulk density and cold crushing strength of samples were evaluated dried and at three fired states (1000 1200 1400 °C). EVOLUTION OF OXYGEN ISOTOPIC COMPOSITION IN THE INNER SOLAR NEBULA Alexander N. Krot 1 Ian D. Hutcheon 2 Hisayoshi Yurimoto 3 Jeffrey N. Cuzzi 4 Kevin D. McKeegan 5 Edward R. D. Scott 1 Guy Libourel 6 7 Marc Chaussidon 6 Jerome Ale´on 6 and Michael I. Petaev8 Received 2004 September 27 accepted 2004 December 17
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JPHACastable refractoryGoogle Patents
CONSTITUTION This castable refractory is alumina-spinel- alumina-magnesiaor alumina-based one being made from an alumina stock such as sintered alumina or fused alumina. In this castable refractory 10-50wt. of a fused alumina with a bulk specific gravity of as low as 2.63-3.10 and a granular diameter of as coarse as 6-50mm is blended. Magnesium aluminate (MgAl2O4) spinel (MAS) is a synthetic material with cubic crystal structure and excellent chemical thermal dielectric mechanical and optical properties.
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Study of Spinel-Containing High Alumina Castable with
High alumina castable with presynthesized and in situ spinel formation is studied using two different lime-containing high alumina cements. Vibratable castable compositions were studied by conventional processing using a distribution coefficient of 0.29 and heat treatments at 110 900 and 1500°C. More recently Braulio studied the effect of alumina particle size on controlling the expansion of alumina-magnesia refractories. 19 20 It was found that colloidal alumina suspension with nanoscale size pre- sented the best performance. In the present work in situ spinel is formed by reaction between colloidal alumina and MgO matrix.
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A magnesia-alumina type spinel clinker contains Fe 2 O 3 and TiO 2 at boundaries between crystal grains and a refractory produced by using the clinker has excellent corrosion resistance and cement coating properties. The refractory can thus be applied to the fields of cement rotary kiln refractories refractories for iron making steel making and nonferrous refining and the like. J. Am. Ceram. Soc. 92 8 1895–1900 (2009) DOI 10.1111/j..2009.03133.x r 2009 The American Ceramic Society Journal Spinel-Coated Graphite for Carbon Containing Refractory Castables Sunanda Mukhopadhyay w Sarbasree Dutta Sheikh A. Ansar Sumita Das and Susmita Misra Department of Chemical Technology University of Calcutta Kolkata 700 009 India Oxidation
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Evolution of an alumina-magnesia/self-forming spinel
The results showed that the processes of spinel formation and nucleation are not strongly affected by the MgO content but that the crystal growth is enhanced for samples with 6.0 wt MgO. Hibonite (CA6) bonding in the castable matrix showed a needlelike structure that could increase hot High alumina castable with presynthesized and in situ spinel formation is studied using two different lime-containing high alumina cements. Vibratable castable compositions were studied by conventional processing using a distribution coefficient of 0.29 and heat treatments at 110 900 and 1500°C.
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The Influence of TiO 2 Addition on the Modulus of Rupture
The addition of TiO 2 to alumina-magnesia refractory castables could accelerate the in situ spinel and calcium hexa-aluminate (CA 6) formation and change the phase evolution which will have direct effect on the overall modulus of rupture values.The cold (CMOR) and hot (HMOR) modulus of rupture thermal expansion and elastic modulus of alumina-magnesia refractory castables with different J. Am. Ceram. Soc. 92 8 1895–1900 (2009) DOI 10.1111/j..2009.03133.x r 2009 The American Ceramic Society Journal Spinel-Coated Graphite for Carbon Containing Refractory Castables Sunanda Mukhopadhyay w Sarbasree Dutta Sheikh A. Ansar Sumita Das and Susmita Misra Department of Chemical Technology University of Calcutta Kolkata 700 009 India Oxidation
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(PDF) Engineered expansion routes for alumina-magnesia
Alumina-magnesia refractory castables are well known for their expansive behavior which is usually associated to the in-situ spinel formation at temperatures in the range of 1000 and 1500°C. This IntroductionMagnesium aluminate spinel (MgAl 2 O 4 ) offers a desirable combination of properties for use in ceramics and refractory industry as high melting point high strength resistance to chemical attack and low electrical losses 1 2 .Preparation of spinel can be made by reaction of magnesium and aluminum compounds.
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Porogenesis in the Alumina-Brucite-Magnesia-Spinel System
Abstract Magnesium monoaluminate spinel (MgAl 2 O 4) is an important raw material for the refractory industry and its in-situ formation from Al 2 O 3 and MgO sources is an expansive process due to its low density. Such an expansion can be a serious drawback for the production of dense structural bricks and castables since it frequently causes deformations and cracks and hinders particles Abstract. To investigate the formation mechanism of calcium hexaluminate (CaAl 12 O 19 CA 6) the analytically pure alumina and calcia used as raw materials were mixed in CaO/Al 2 O 3 ratio of 12.57 137.43 by mass. The raw materials were ball-milled and
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Spinel Meanings and Crystal PropertiesThe Crystal Council
Spinel is a rare aluminum magnesium oxide mineral that crystallizes in the form of octahedral crystals dodecahedral cubic and massive formations. It can be seen in a variety of different colors such as red blue green violet black yellow orange grey brown white and even colorless. The Sun is 16O-enriched (Δ17O = −28.4 ± 3.6‰) relative to the terrestrial planets asteroids and chondrules (−7‰ < Δ17O < 3‰). Ca Al-rich inclusions (CAIs) the oldest Solar System solids approach the Sun s Δ17O. Ultraviolet CO self-shielding resulting in formation of 16O-rich CO and 17 18O-enriched water is the currently favored mechanism invoked to explain the observed
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(PDF) Engineered expansion routes for alumina-magnesia
Alumina-magnesia refractory castables are well known for their expansive behavior which is usually associated to the in-situ spinel formation at temperatures in the range of 1000 and 1500°C. This Ferritic weld metal deposited with a self-shielded arc-welding process has intentional additions of aluminum magnesium titanium and zirconium. This results in a complex precipitation process that has been characterized with a combination of electron microscopy techniques. This work indicates that the formation of a spinel oxide is critical for the nucleation of nitrides of zirconium and
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Evolution of an alumina-magnesia/self-forming spinel
This study was carried out in conjunction with the investigation reported in Part I on the microstructural characteristics of an alumina-spinel castable with several percentages of MgO content. Bulk density and cold crushing strength of samples were evaluated dried and at three fired states (1000 The evidence shows that the formation of a spinel oxide is critical for the nucleation of nitrides of zirconium and titanium and prevents the agglomeration of aluminum rich oxides and the formation of large aluminum nitrides. The evolution of precipitate formation is critical to limit large inclusions and improve weld metal toughness.
Get PriceEvolution of an alumina-magnesia/self-forming spinel
On the basis of the microstructural investigation of an alumina-magnesia/self-forming spinel castable it can be concluded that (1) Spinel formation in the matrix of the castable could be achieved at temperatures around ° C and the amount of spinel phase would steadily increase with higher temperatures. Synthesis of magnesium aluminate spinel (MgAl2O4) was investigated by employing ball milling and co-precipitation methods. The starting materials (aluminum hydroxides) were obtained from the purified sodium hydroxide leaching solution of black dross. The characteristics of the synthesized spinel was analyzed through X-ray diffraction (XRD) scanning electron microscopy (SEM) images.
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Microstructure and phase evolution of alumina–spinel self
Apr 01 2011 · M. Fuhrer A. Hey W.E. LeeMicrostructural evolution in self-forming spinel/calcium aluminate-bonded castable refractories Journal of the European Ceramic Society 18 (7) (1998) pp. Google Scholar spinel-alumina castables prepared by hydrated magne-sium aluminate gels 18-24 . Instead of magnesia fines (used traditionally) those castables are bonded with sol gel derived and conventionally coprecipitated spinel gels 25 26 . Amodified method for preparing magnesia aluminate gel had been suggested by some authors
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(PDF) Spinel-Coated Graphite for Carbon Containing
J. Am. Ceram. Soc. 92 8 1895–1900 (2009) DOI 10.1111/j..2009.03133.x r 2009 The American Ceramic Society Journal Spinel-Coated Graphite for Carbon Containing Refractory Castables Sunanda Mukhopadhyay w Sarbasree Dutta Sheikh A. Ansar Sumita Das and Susmita Misra Department of Chemical Technology University of Calcutta Kolkata 700 009 India Oxidation Abstract. Results of a technological synthesis of alumina-magnesia spinel from a range of doped magnesia-containing raw materials at different temperatures under laboratory conditions are reported. Synthetic chromite-doped spinel with excess periclase is recommended for manufacture of magnesia-spinelide refractories.
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