Effect of Nano- sized Fe2O3 on Microstructure and Hydration Resistance of MgO-CaO Refracrories

Subject Areas :

سلمان قاسمی کهریزسنگی ¹ , علی نعمتی ² , عزیز شهرکی ³

1 - دانشگاه صنعتی شریف
2 - دانشگاه صنعتی شریف
3 - دانشگاه صنعتی شریف

Received: 2015-06-19 Accepted : 2016-09-13 Published : 2016-08-22

Keywords: MgO-CaO Refractory, Hydration, Nano-Sized Fe2O3,

Abstract :

Magnesia–Doloma refractories are considered as a mixed product of alkali products i.e. sintered (fused) magnesia and doloma in which 50-80wt% magnesia is contained. These refractories enjoy some advantages such as high slag resistance corrosion, high-temperature performance, potential for production of pure molten iron and low cost due to abundance of magnesia and doloma resources in access. However, poor resistance of hydration can be cited that may constrain the amount of this refractory in various industrial applications. in this work the effect of nano-sized Fe2O3 on microstructure and hydration resistance  of MgO-CaO refractories with 35wt.% CaO were investigated. MgO-CaO refractories with 35wt.% CaO content were prepared by using dolomite and magnesite calcined as starting material and nano-sized Fe2O3 as additive. Samples were uniaxially pressed in to briquettes at a pressure of 90 MPa. Briquettes after drying at 110 for 24 hr were sintered at 1650 for 3 hr. Hydration resistance was measured at 25oC in 95% relative humidity through the weight gain after 72 hr. according to the results, with the addition of nano-sized Fe2O3, bulk density and hydration resistance of the samples increase while apparent porosity decreased. Densification of MgO-CaO refractories was promoted with increase of nano-sized Fe2O3 content. nano- sized Fe2O3 addition lead to formation low melting phases such as C2F(2CaO.Fe2O3), CF(CaO.Fe2O3) and C3A(3CaO.Al2O3). Formation of this low melting point surrounding the CaO and MgO grain and grain boundaries and promoted densification of MgO-CaO refractories. The nature of nano-sized Fe2O3 promoting densification is promoting the liquid phase sintering.

References:

[1]       ز. نعمتی، کتاب دیرگدازهای سرامیکی، تهران دانشگاه صنعتی شریف، موسسه انتشارات علمی چاپ اول، 1382.

 

[2]     F. kashaninia, H. sarpoolaky, R. Naghizade, A. R. Bagheri & A. R. Zamanipour, “improving hydration resistance of Magnesia –Doloma refractores by iron oxid addition”, Iranian journal of material science &engineering, Vol. 8, No.4, 2011.

 

[3]       م. زراعتی،ح. سرپولکی ،ف. گلستانی فرد، م. باوندچالی، ع. باقری، ع. پناهی، "بررسی پارامترهای موثر بر ساخت و نوع افزودنی بر زینتر منیزیا- دولومای مصرفی در صنایع فولاد"، سمپوزیوم فولاد 89.

 

[4]       ا. کاظمی، "تاثیر افزودن زیرکونیا بر خواص دیرگدازهای منیزیا- اسپینلی"، پایان نامه کارشناسی ارشد، دانشگاه صنعتی شریف، سال 1381.

 

[5]     M. Hadian & B. Nazari, “InfluEence of Mgnesia Addition on Hydration of Iranian Dolomite”, Iranian Journal of Materials Science & Engineering, Vol. 7, 2010.

 

[6]     K. Ghosh, B. Bhattacharya, H. S. Mukherjee, S. Tripathi & K. Das, “Effect of Fe₂O₃ On The Densification And Properties of Lime”, Ceramics –Silikáty, pp. 70-74, 2003.

 

[7]     G. M. Otham, M. A. Abuel & M. A. Serry, “hydration–resistant lime refractories from Egyption lime stone and ilmenite raw materials”, ceramics international, pp. 801-807, 2001.

 

[8]     S. Chen & P. Lu, “Improved Hydration Resistance of Synthesized Magnesia–Calcia Clinker by Surface Modification”, J. Am. Ceram. Soc, Vol. 87, pp. 2164–2167, 2004.

 

[9]     J. lee, H.S. Choi & S. j. Lee, “Effect of Fe₂O₃ Addition On The Hydration Resistance of CaO” , Journal of ceramic processing research, Vol. 13, No.5, pp. 6406-650, 2012.

 

[10] J. l. Prodriguez, B. Ferandez, J. C. Rendon, P. Pena & J. F. Valle, “Reaction Sintering of  Mexican Dolomite – Zircon Mixtures”, Bol. Soc. Esp. Ceram, Vol. 44, pp. 245-250, 2005.

 

[11] M. Chen, C. Lu & J. YU, “improvement in performance of MgO-CaO refractories by addition of nano –ZrO₂”, Journal of the European ceramic society, Vol. 27, pp. 4633-4638, 2007.

 

[12] J. lee, H. S. Choi & S. j. Lee, “effect of Fe₂O₃ addition on the hydration resistance of CaO”, Journal of ceramic processing research, Vol. 13, No. 5, pp. 640-650, 2012.

 

[13] H. I .Moorkah & M. S. Abolarin, “investigation of the properties of locally available dolomite for refractory applicatios”, Nigerian Journal Of Technology, Vol. 24, No. 1, 2005.

 

[14] G. M. Otham, M. A. Abuel & M. A. Serry, “Hydration – Resistant lime Refractories From Egyption lime Stone And Ilmenite Raw Materials”, ceramics international, pp. 801-807, 2001.

 

[15]    م. جلالی، ا. نور بخش و ا. منشی،" اثر افزودن نانو اسپینل آلومینا-منیزیا بر مقاومت به هیدراتاسیون جرم های ریختنی بدون  سیمان منیزیایی" فصلنامه  علمی پزوهشی فرآیند های نوین در مهندسی مواد،سال نهم، شماره دوم، تابستان 1394.

[16]    ح. پایدار و ج. طراح، "بررسی اثر افزودن TiO₂‌بر کیفیت مخلوط رس های نسوز معادن سمیرم و قشلاق در ارتباط با کاربرد ان در صنعت نسوز"، فصلنامه علمی پزوهشی فرآیند های نوین در مهندسی مواد، سال دهم، شماره اول، بهار 1395.