High purity alumina - spinel （ A - MA ） and alumina- magnesia （A -M） castables are widely used in steel ladles due to their resistance against slag penetration and corrosion. With a calcium magnesium alumihate bo...High purity alumina - spinel （ A - MA ） and alumina- magnesia （A -M） castables are widely used in steel ladles due to their resistance against slag penetration and corrosion. With a calcium magnesium alumihate bond （ CMA ） excellent slag penetration resistance can be achieved which results in high wear resistance due to reduced structural spalling. This paper investigates the impact of matrix eompositions and CMA-binder content of A -MA and A -M castables on thermal shock resistance（TSR）. Standardized thermal shock tests have been applied with sample quenching from 950 ℃ down to room temperature. Results show that all castables are significantly damaged after 5 cycles despite their differences in microstructure. However, the mix with 12% CMA gave TSR that is at similar good level as the reference mix with 6% CAC （70% alumina cement ）. While a similar strength level was achieved before and after the thermal cycling, the Jormulation with 12% CMA contains 0. 6% less total CaO. The A - MA castables perform better on average than the A - M mixes with this test method. Within the group of A - M castables the mix with 18% CMA and 0. 5% SiO2 gave superior TSR, similar good as castables of the A - MA group. The introduction of CMA in an A - M tastable allows reduction of free MgO and SiO2-addition. The reduction of SiO2 has been found beneficial for the TSR. This was also found during a thermal cycling trial at high temperature between 1100 and 1 500 ℃. Here the A -M mix with 18% CMA and 0. 5% SiO2 performed better than the SiO2-free A -MA castable.展开更多
文摘High purity alumina - spinel （ A - MA ） and alumina- magnesia （A -M） castables are widely used in steel ladles due to their resistance against slag penetration and corrosion. With a calcium magnesium alumihate bond （ CMA ） excellent slag penetration resistance can be achieved which results in high wear resistance due to reduced structural spalling. This paper investigates the impact of matrix eompositions and CMA-binder content of A -MA and A -M castables on thermal shock resistance（TSR）. Standardized thermal shock tests have been applied with sample quenching from 950 ℃ down to room temperature. Results show that all castables are significantly damaged after 5 cycles despite their differences in microstructure. However, the mix with 12% CMA gave TSR that is at similar good level as the reference mix with 6% CAC （70% alumina cement ）. While a similar strength level was achieved before and after the thermal cycling, the Jormulation with 12% CMA contains 0. 6% less total CaO. The A - MA castables perform better on average than the A - M mixes with this test method. Within the group of A - M castables the mix with 18% CMA and 0. 5% SiO2 gave superior TSR, similar good as castables of the A - MA group. The introduction of CMA in an A - M tastable allows reduction of free MgO and SiO2-addition. The reduction of SiO2 has been found beneficial for the TSR. This was also found during a thermal cycling trial at high temperature between 1100 and 1 500 ℃. Here the A -M mix with 18% CMA and 0. 5% SiO2 performed better than the SiO2-free A -MA castable.
