Using sintered corundum as aggregate, white fused corundum powder, fused spinel powder, ultra-fine a-A12 0 3, nano calcium carbonate and hydrated alumina as matrix, effects of nano calcium carbonate additions （0. 4%,...Using sintered corundum as aggregate, white fused corundum powder, fused spinel powder, ultra-fine a-A12 0 3, nano calcium carbonate and hydrated alumina as matrix, effects of nano calcium carbonate additions （0. 4%, O. 8%, 1.2%, 1.6% and 2. 0% in mass, the same hereinafter） on modulus of rupture, thermal shock resi.~tanee and slag resistance of corundum -spinel castables after treating at different temperatures were studied. The results show that nano calcium carbonate decomposes at high temperatures and in-situ forms ealci- ant aluminates, which can significantly increase the CMOR and HMOR of the castables after treating at 800 -1 400 ℃ ; adding nano calcium carbonate obviously improves the thermal shock resistance of the castables, and has little influence on the high basicity slag resist- ance, however, significantly decreases the corrosion and penetration resistance to low basicity slag.展开更多
Corundum spinel castable was prepared using tabular corundum as aggregates,white fused corundum powder,spinel powder and alumina powder as the matrix,pure calcium aluminate cement as a binder,and extra adding calcium ...Corundum spinel castable was prepared using tabular corundum as aggregates,white fused corundum powder,spinel powder and alumina powder as the matrix,pure calcium aluminate cement as a binder,and extra adding calcium chloride(0,1%,2%,and 3%,by mass).The effects of the CaCl2 addition on the cold physical properties,the hot strength,the thermal shock resistance and the microstructure of the castable were studied.The results show that,for the corundum spinel castable fired at 1550℃,with the increase of the CaCl2 addition from 0 to 3%,the cold strengthes first increase,then decrease,the apparent porosity increases,the volume density decreases,and the linear change rate first decreases and then increases,while the overall change is not significant;however,the hot modulus of rupture and the thermal shock resistance are obviously improved.This is mainly due to that,CaCl2 is evenly distributed in the castable in the form of solution,and reacts with Al2O3 to form small flake CA6 crystals,which evenly distributed in the sample matrix strengthening and toughening the material.展开更多
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
The study focused on investigating the effectiveness of functional acrylic polymer (AP) in improving the ability of airfoamed sodium silicate-activated calcium aluminate/Class F fly ash cement (slurry density of ￡1.3...The study focused on investigating the effectiveness of functional acrylic polymer (AP) in improving the ability of airfoamed sodium silicate-activated calcium aluminate/Class F fly ash cement (slurry density of ￡1.3 g/cm3) to mitigate the corrosion of carbon steel (CS) after exposure to hydrothermal environment at 200?C or 300?C. Hydrothermally-initiated interactions between the AP and cement generated the formation of Ca-, Al-, or Na-complexed carboxylate derivatives that improved the AP’s hydrothermal stability. A porous microstructure comprising numerous defect-free, evenly distributed, discrete voids formed in the presence of this hydrothermally stable AP, resulting in the increase in compresive strength of cement. The foamed cement with advanced properties conferred by AP greatly protected the CS against brine-caused corrosion. Four major factors governed this protection by AP-incorporated foamed cements: 1) Reducing the extents of infiltration and transportation of corrosive electrolytes through the cement layer deposited on the underlying CS surface;2) Inhibiting the cathodic reactions at the corrosion site of CS;3) Extending the coverage of CS by the cement;and 4) Improving the adherence of the cement to CS surface.展开更多
文摘Using sintered corundum as aggregate, white fused corundum powder, fused spinel powder, ultra-fine a-A12 0 3, nano calcium carbonate and hydrated alumina as matrix, effects of nano calcium carbonate additions （0. 4%, O. 8%, 1.2%, 1.6% and 2. 0% in mass, the same hereinafter） on modulus of rupture, thermal shock resi.~tanee and slag resistance of corundum -spinel castables after treating at different temperatures were studied. The results show that nano calcium carbonate decomposes at high temperatures and in-situ forms ealci- ant aluminates, which can significantly increase the CMOR and HMOR of the castables after treating at 800 -1 400 ℃ ; adding nano calcium carbonate obviously improves the thermal shock resistance of the castables, and has little influence on the high basicity slag resist- ance, however, significantly decreases the corrosion and penetration resistance to low basicity slag.
文摘Corundum spinel castable was prepared using tabular corundum as aggregates,white fused corundum powder,spinel powder and alumina powder as the matrix,pure calcium aluminate cement as a binder,and extra adding calcium chloride(0,1%,2%,and 3%,by mass).The effects of the CaCl2 addition on the cold physical properties,the hot strength,the thermal shock resistance and the microstructure of the castable were studied.The results show that,for the corundum spinel castable fired at 1550℃,with the increase of the CaCl2 addition from 0 to 3%,the cold strengthes first increase,then decrease,the apparent porosity increases,the volume density decreases,and the linear change rate first decreases and then increases,while the overall change is not significant;however,the hot modulus of rupture and the thermal shock resistance are obviously improved.This is mainly due to that,CaCl2 is evenly distributed in the castable in the form of solution,and reacts with Al2O3 to form small flake CA6 crystals,which evenly distributed in the sample matrix strengthening and toughening the material.
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.
文摘The study focused on investigating the effectiveness of functional acrylic polymer (AP) in improving the ability of airfoamed sodium silicate-activated calcium aluminate/Class F fly ash cement (slurry density of ￡1.3 g/cm3) to mitigate the corrosion of carbon steel (CS) after exposure to hydrothermal environment at 200?C or 300?C. Hydrothermally-initiated interactions between the AP and cement generated the formation of Ca-, Al-, or Na-complexed carboxylate derivatives that improved the AP’s hydrothermal stability. A porous microstructure comprising numerous defect-free, evenly distributed, discrete voids formed in the presence of this hydrothermally stable AP, resulting in the increase in compresive strength of cement. The foamed cement with advanced properties conferred by AP greatly protected the CS against brine-caused corrosion. Four major factors governed this protection by AP-incorporated foamed cements: 1) Reducing the extents of infiltration and transportation of corrosive electrolytes through the cement layer deposited on the underlying CS surface;2) Inhibiting the cathodic reactions at the corrosion site of CS;3) Extending the coverage of CS by the cement;and 4) Improving the adherence of the cement to CS surface.
