Hydration Resistance Improvement of MgO-CaO Refractories by the Addition of Nano-ZrO2

Subject Areas : journal of New Materials

سلمان Ghasemi-Kahrizsangi ¹ , علی Nemati ² , عزیز Shahraki ³ , محمد Farooghi ⁴

1 - داشجوی کارشناسی ارشد، دانشکده مهندسی و علم مواد، دانشگاه صنعتی شریف ، تهران، ایران
2 - دانشیار دانشکده مهندسی و علم مواد، دانشگاه صنعتی شریف، تهران، ایران
3 - دانشجوی کارشناسی ارشد، دانشکده مهندسی و علم مواد، دانشگاه صنعتی شریف ، تهران، ایران
4 - دانشجوی کارشناسی ارشد، دانشکده مهندسی و علم مواد، دانشگاه صنعتی شریف ، تهران، ایران

Received: 2015-07-31 Accepted : 2017-11-16 Published : 2017-08-23

Keywords: Magnesi-Doloma, Refractories, Hydration Resistance, Nano-ZrO2,

Abstract :

Abstract
Magnesia-doloma refractories are alkali products from sintered (or fusion) doloma and magnesia fusion), which have 50-80 wt. % MgO. These refractory have many advantages such as high corrosion resistance against slag, high temperature performance, ability to produce clean meet, and cost-effective (due to the abundance of dolomite and magnesite ores in Iran). However, the use of this type of refractories has been faced with restrictions due to poor hydration resistance in various industries. In this study, the effect of adding zirconium oxide nanoparticles on microstructure and hydration resistance of magnesia – doloma refractories containing 35 wt. % CaO is evaluated. Cylindrical samples were  pressed under pressure 90MPa, and after it were dried and  fired  at 110 ℃ for 24 h and, heated t₀ 1650℃  with 5min / ℃  the for 3 h.  Results show that the positive  effect of adding zirconium oxide nanoparticles on the sintering temperature samples, due to the larger atomic radius of Mg than  Ca thus lower the bond strength of Mg-O tend replacement Ca^{2 +} with  Zr ^{+ 4} cations network with CaO  greater than Mg^{2 +}in MgO  networks and the formation of calcium zirconate phase (CaZrO₃). According to the result it can be found thet in doloma free CaO reduced by creating (CaZrO₃) phase, as well as cavities formed by replacing the cationic in the network, increased the diffusion and sintering process which it led to creates a more dense structure and hydration resistant improvement.

References:

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