Effects of different zirconia-based raw materials on properties of MgO-Al-C materials.

To improve their thermal shock resistance, MgO-Al-C materials were prepared using sintered magnesia 98, fused magnesia 98, Al powder, carbon black N220 (25 -20 nm), granulated zirconia micropowder, and zirconia hollow cenosphere as raw materials and phenolic resin as the binder. The effects of the granulated zirconia micropowder addition (0,1%, 2%, 3% and 4%, by mass) and the zirconia hollow cenosphere addition (0,2%, 4% and 6%, by mass) on the cold and the hot properties, the phase composition and the microstructure of the samples were researched. The results show that: (1) the granulated zirconia micropowder is agglomerates with porous structure and compressibility, which can absorb thermal stress; with the addition of 2%, the thermal shock resistance of the sample is improved, the strength retention ratio increases by 3.9% compared with that of the original sample Z0, and other properties are almost the same as those of sample Z0; (2) the zirconia cenosphere has a hollow structure with elasticity, which can also absorb thermal stress; with the addition of 4%,the thermal shock resistance of the sample significantly improves with the strength retention ratio increasing by 8% compared with that of sample Z0; the apparent porosity is 12.4%,the bulk density is 2.87 g ⋅ cm^-3, the density is higher than that of sample Z0; the oxidation resistance improves to a certain extent with the thickness of the oxidation layer decreasing by 0.15 mm compared with that of sample Z0, and other properties do not significantly change compared with those of sample Z0. [ABSTRACT FROM AUTHOR]