Iranian Nanotechnology Society International Journal of Nanoscience and Nanotechnology 1735-7004 12 1 2016 03 01 Effect of Nano-Sized Fe2O3 on Microstructure and Hydration Resistance of MgO-CaO Refractories 19 26 19216 EN S. G. Kahrizsangi Department of Materials Science and Engineering, Sharif University of Technology, Tehran, I.R.Iran A. Nemati Department of Materials Science and Engineering, Sharif University of Technology, Tehran, I.R.Iran A. Shahraki Department of Materials Science and Engineering, Sharif University of Technology, Tehran, I.R.Iran M. Farooghi Department of Materials Science and Engineering, Sharif University of Technology, Tehran, I.R.Iran Journal Article 2015 04 29 <em>In this work the effect of Nano-sized Fe<sub>2</sub>O<sub>3</sub> on microstructure and hydration resistance of MgO-CaO refractories with 35 wt% CaO was investigated. MgO-CaO refractories with  35 wt% CaO content was prepared by using dolomite and magnesite calcined as starting materials and Nano-sized Fe<sub>2</sub>O<sub>3</sub> (2,4, 6 and 8 wt%) as an additive. Samples were pressed into briquettes at a pressure of 90 MPa. Briquettes after drying at 110<sup> o</sup>C for 24 hours were sintered at 1650<sup> o</sup>C for 3 hours. Hydration resistance was measured at 25<sup> o</sup>C in 95% relative humidity through the weight gain after 72 hours. According to the results, it is observed that when the amount of Nano-sizedFe<sub>2</sub>O<sub>3</sub> added increased to 8 wt% the bulk density increased to 3.14 gr/cm<sup>3</sup> and apparent porosity decreased to 8.20%. For the sample without addition, the mass gain after 72 hours was 1.76, which sharply decreased to 1.27 with increasing the amount of Nano-sized Fe<sub>2</sub>O<sub>3</sub>. With the addition of Nano-sized Fe<sub>2</sub>O<sub>3</sub>, bulk density and hydration resistance of the samples increased while apparent porosity decreased. Densification of MgO-CaO refractories was promoted to increase of Nano-sized Fe<sub>2</sub>O<sub>3</sub> content. Nano-sized Fe<sub>2</sub>O<sub>3</sub> addition led to formation of low melting phases such as C<sub>2</sub>F (2CaO.Fe<sub>2</sub>O<sub>3</sub>), CF (CaO.Fe<sub>2</sub>O<sub>3</sub>) and C<sub>3</sub>A (3CaO.Al<sub>2</sub>O<sub>3</sub>). The formation of this low melting point phases surrounding the CaO and MgO grain and grain boundaries and promoted densification of MgO-CaO refractories. The nature of Nano-sized Fe<sub>2</sub>O<sub>3</sub> promoting densification is increasing the liquid phase sintering.</em> Hydration resistance Densification Refractory Nano-sized Fe2O3 https://www.ijnnonline.net/article_19216_f6bb6d65c8c39c685424a156838f6853.pdf