Abstract: When the formula and raw materials are fixed, the composition, structure and properties of high alumina porcelain largely depend on the firing system. Changes of phase composition, microstructure and mechanical properties of high alumina porcelain with sintering temperature were systematically studied, and the reasons were analyzed. The results show that with the increase of sintering temperature from 1 160 ℃ to 1 310 ℃, the amount of fused corundum and quartz particles in porcelain increases, the content of corundum phase decreases from 37.85% (mass fraction, the same below) to 35.02%, and the content of quartz phase decreases from 7.60% to 1.94%. The fused corundum and some quartz precipitate in the form of mullite, and the content of mullite phase in porcelain increases from 7.49% to 11.41%. As sintering temperature increases from 1 160 ℃ to 1 280 ℃, the content of glass phase in porcelain increases from 47.06% to 51.63%, while the true porosity of porcelain decreases from 12.50% to 5.59%. However, when sintering temperature reaches 1 310 ℃, the porcelain are overburning, therefore the true porosity increases to 6.99%. When sintering temperature is 1 160 ℃, the porcelain is undersintering with open pores, and the bending strength is only 151 MPa. When sintering temperature increases to 1 190 ℃, the bending strength reaches a maximum value of 181 MPa. As sintering temperature continues to rise to 1 310 ℃, the total content of crystalline phases in pocelain decreases from 52.94% to 48.37%, indicating that the crystalline particles which play a dispersion enhancing role in porcelain decrease, thus the strength of porcelain gradually decreases from 181 MPa to 158 MPa. These research results have important reference significance for optimizing the formulation, firing system and material properties of high alumina porcelain.

Key words: high alumina porcelain, sintering temperature, phase composition, microstructure, mechanical property, dispersion strengthening