Effect of galaxite on the properties of magnesia refractories

A periclase-galaxite refractory is prepared using high-purity sintered magnesia and galaxite particles as raw materials, with pulp waste liquid serving as a binder. The effects of particle size and quantity of added galaxite on the properties of the magnesia refractories are determined. As the quantity of fine galaxite powder increased, the cold modulus of rupture (CMOR) of the sample gradually decreased, and the hot modulus of rupture (HMOR) of the sample gradually increased. With a fine powder content of 4 wt%, the CMOR is 22.8 MP. Similarly, with a fine powder content of 12 wt%, the HMOR is 29.6 MP. The addition of galaxite improves the thermal shock resistance of magnesia refractories, with galaxite particles having a stronger effect than the fine powder. A sample with a particle content of 8 wt% exhibited the highest residual strength retention rate, which is 32.4 % higher than that of the pure magnesia refractory sample. At high temperatures, a Mg-Mn-Al composite spinel was formed in the material owing to the interdiffusion of Mn2+ and Mg2+, which promoted bonding and improved the strength of the material. The mismatch in the thermal expansion of the manganite spinel and periclase resulted in microcracks inside the material, thereby improving its thermal shock resistance.