Performance improvement of MgO-C refractory bricks by the addition of Nano-ZrSiO4

Abstract

Many benefits of the MgO-C refractory bricks such as excellent corrosion resistance, high thermal shock resistance, good mechanical strength at high temperatures, and permeability have attracted attention of consumers in various industries. But on the other hand, the low oxidation resistance of these refractory bricks at high temperatures has restricted their application. For this purpose, in this research study, the impact of Nano-ZrSiO4 addition on microstructure and performance of MgO-C refractory was investigated. 0, 0.5, 1, 1.5, and 2 wt % of Nano-ZrSiO4 was added to compositions. After samples preparation, all specimens tempered and fired (in a coke bed) at the 250 °C and 1600 °C for 8 h and 3 h, respectively. Results showed that addition of Nano-ZrSiO4 led to generation some phases such as zirconia carbide (ZrC), forsterite (2MgO.SiO2), and enstatite (MgO.SiO2). Formation of aforementioned phases results in improving properties of MgO-C bricks through the following ways (i) converting free-graphite phase to high oxidation resistance phases such as ZrC phase, (ii) creating a dense matrix by formation low melting phase such as MgO.SiO2 which decreases the voids and porosities (reduce the oxygen penetration ways into the matrix), and (iii) covering free graphite phase and protect it from the oxidation.