关键词: 菱镁矿, 镁锆砂, 稀土氧化物, 抗热震性

Abstract: To make full use of the low-grade magnesite in southern Liaoning Province and prepare high-quality synthetic magnesia,magnesia-zirconia samples were prepared using Xiuyan secondary magnesite and desilicated zirconia as the main raw materials,adding 2 mass% rare earth oxides (CeO₂,Y₂O₃ and La₂O₃,respectively) as the additive,heating at 1 500,1 600 and 1 700 ℃ for 3 h.Effects of rare earth oxide types and heat treatment temperatures on the properties and the microstructure of the samples were studied.The results show that:(1)compared with the samples without rare earth oxides,the samples with rare earth oxides have better thermal shock resistance,higher bulk density and lower apparent porosity;(2)after heat treatment at 1 700 ℃ for 3 h,the magnesia-zirconia sample with 2% CeO₂ has the highest bulk density,the lowest apparent porosity and the best thermal shock resistance.

Key words: magnesite, magnesia-zirconia powder, rare earth oxide, thermal shock resistance