To enhance the serdice life of magnesia based slag dam, composite slag dam was designed to be cast with alumina magnesia castables in slag line and magnesia castables in molten steel zone. Workability of the magnesia ...To enhance the serdice life of magnesia based slag dam, composite slag dam was designed to be cast with alumina magnesia castables in slag line and magnesia castables in molten steel zone. Workability of the magnesia castables for the slag dam was improved and a suitable vibration shaping method was adopted to combine it with alumina magnesia castables. The result shows： （1） workability and setting performance of magtwsia castables can be improved to match with alumina magnesia castables by adjusting setting retarder and water reducing agent, and adding proper silica fume ; （2） composite slag dam cart be prepared with alumina m,agnesia castables and the improved magnesia castables, whether by up - down composite method or right - left composite method; in order to get full vibration arrd make interface .fluctuation have proper amplitude, the vibration time oJ the two methods after two different castables contact with each other is 3 and 2.5 minutes, respectively; （3）the result of the on-site test proves that the design aims for reducing pollution to hot metal and improving corrosion resistance have been achieved.展开更多
Alumina magnesia castable crucible specimens were prepared using tabular corundum （ ≤ 5 mm ）, fused magnesia powder （ ≤0. 088 mm ） , fused spinel powder （ ≤0. 044 mm ） , and α-Al2O3. micropowder （d50 ≤0....Alumina magnesia castable crucible specimens were prepared using tabular corundum （ ≤ 5 mm ）, fused magnesia powder （ ≤0. 088 mm ） , fused spinel powder （ ≤0. 044 mm ） , and α-Al2O3. micropowder （d50 ≤0. 7 μm ） as main starting materials, batching, mixing, shaping, and drying. Slag resistance was determined by static crucible method at 1 600℃ for 3 h adopting two ladle slags with different basicities （3. 40 and 1.03 ）. The corrosion and penetration indexes and microstructure characteristics of the specimens after slag resistance test were analyzed to study the corrosion behaviors of the two slags to alumina magnesia castables. The results show that the corrosion of the low basicity slag to alumina magnesia custables is much more serious than that of the high basicity slag for that their reactions with castables form different products;for the low basicity slab,, the multi-phase coexistence of CA6 and compounds of CaO - Al2O3 -SiO2 in the materials together with volume expansion caused by the formation of CA6 intensify the slag corrosion and penetration ; for the high basicity slag, the reaction between slag and castables generates a CA2 dense layer and a large amount of in-situ MA in the interface, reducing the slag corrosion to the materials effectively.展开更多
CMA72 bonded Al2 O3 - MgO castable is promising for application of steel ladle wall, because of unique combination of thermo-mechanical properties, slag corro- sion resistance and cost benefit. In these castables, mi-...CMA72 bonded Al2 O3 - MgO castable is promising for application of steel ladle wall, because of unique combination of thermo-mechanical properties, slag corro- sion resistance and cost benefit. In these castables, mi- crosilica can be introduced to counterbalance the expan- sion generated by spinel formation. In this paper, the of microsilica dosage on properties of eastables was evaluated. Expansion, expressed by the permanent linear change （PLC）, is highly dependent on the dosage of microsilica. Unexpected expansion occurs when the dos- age of microsilica is too low due to dominant effect of spinel and CA6 formation. Too high dosage results in sintering shrinkage, which is related to amount of liquid phase generated by microsilica addition. In addition, HMOR declines dramatically with increasing microsilica dosage. Considering the balance between expansion con- trol and hot property retention, 1.0 mass% of microsili- ca is recommended for the castable containing 4 mass% of magnesia.展开更多
Three different castables based on the Al_2O_3–MgO –CaO system were prepared as steel-ladle purging plug refractories： corundum-based low-cement castable（C-LCC）, corundum-spinel-based low-cement castable（C-S-LCC...Three different castables based on the Al_2O_3–MgO –CaO system were prepared as steel-ladle purging plug refractories： corundum-based low-cement castable（C-LCC）, corundum-spinel-based low-cement castable（C-S-LCC）, and corundum-spinel no-cement castable（C-S-NCC）（hydratable alumina（ρ-Al_2O_3） bonded）. The fracture behavior at room temperature was tested by the method of ＂wedge-splitting＂ on samples pre-fired at different temperatures; the specific fracture energy G′f and notched tensile strength σNT were obtained from these tests. In addition, the Young＇s modulus E was measured by the method of resonance frequency of damping analysis（RFDA）. The thermal stress resistance parameter R′′′′ calculated using the values of G′f, σNT, and E was used to evaluate the thermal shock resistance of the materials. According to the microstructure analysis results, the sintering effect and the bonding type of the matrix material were different among these three castables, which explains their different fracture behaviors.展开更多
Al2O3 -MgO castables have been widely used for working linings of steel ladle due to their superior hot strength and corrosion resistance. In this- work, effects of＂ microsilica, ultrafine alumina and MgO fines addit...Al2O3 -MgO castables have been widely used for working linings of steel ladle due to their superior hot strength and corrosion resistance. In this- work, effects of＂ microsilica, ultrafine alumina and MgO fines additions on the rh, eological behavior of the castables were investi- gated by means of IBB rheometer V1. 0 to measure torque （shear stress） under varying shear rates. The re- sults show that rheological properties of castables at varying shear rates are significantly improved with increase of microsilica additions （from 1 mass% to 5 mass% ） and corresponding decrease in water addition; there is only little change in rheological behavior with variation of ultrafine alumina and MgO fines additions. Optimum ultrafine alumina and microsilica additions are recommended for castables with good rheological behavior.展开更多
文摘To enhance the serdice life of magnesia based slag dam, composite slag dam was designed to be cast with alumina magnesia castables in slag line and magnesia castables in molten steel zone. Workability of the magnesia castables for the slag dam was improved and a suitable vibration shaping method was adopted to combine it with alumina magnesia castables. The result shows： （1） workability and setting performance of magtwsia castables can be improved to match with alumina magnesia castables by adjusting setting retarder and water reducing agent, and adding proper silica fume ; （2） composite slag dam cart be prepared with alumina m,agnesia castables and the improved magnesia castables, whether by up - down composite method or right - left composite method; in order to get full vibration arrd make interface .fluctuation have proper amplitude, the vibration time oJ the two methods after two different castables contact with each other is 3 and 2.5 minutes, respectively; （3）the result of the on-site test proves that the design aims for reducing pollution to hot metal and improving corrosion resistance have been achieved.
文摘Alumina magnesia castable crucible specimens were prepared using tabular corundum （ ≤ 5 mm ）, fused magnesia powder （ ≤0. 088 mm ） , fused spinel powder （ ≤0. 044 mm ） , and α-Al2O3. micropowder （d50 ≤0. 7 μm ） as main starting materials, batching, mixing, shaping, and drying. Slag resistance was determined by static crucible method at 1 600℃ for 3 h adopting two ladle slags with different basicities （3. 40 and 1.03 ）. The corrosion and penetration indexes and microstructure characteristics of the specimens after slag resistance test were analyzed to study the corrosion behaviors of the two slags to alumina magnesia castables. The results show that the corrosion of the low basicity slag to alumina magnesia custables is much more serious than that of the high basicity slag for that their reactions with castables form different products;for the low basicity slab,, the multi-phase coexistence of CA6 and compounds of CaO - Al2O3 -SiO2 in the materials together with volume expansion caused by the formation of CA6 intensify the slag corrosion and penetration ; for the high basicity slag, the reaction between slag and castables generates a CA2 dense layer and a large amount of in-situ MA in the interface, reducing the slag corrosion to the materials effectively.
文摘CMA72 bonded Al2 O3 - MgO castable is promising for application of steel ladle wall, because of unique combination of thermo-mechanical properties, slag corro- sion resistance and cost benefit. In these castables, mi- crosilica can be introduced to counterbalance the expan- sion generated by spinel formation. In this paper, the of microsilica dosage on properties of eastables was evaluated. Expansion, expressed by the permanent linear change （PLC）, is highly dependent on the dosage of microsilica. Unexpected expansion occurs when the dos- age of microsilica is too low due to dominant effect of spinel and CA6 formation. Too high dosage results in sintering shrinkage, which is related to amount of liquid phase generated by microsilica addition. In addition, HMOR declines dramatically with increasing microsilica dosage. Considering the balance between expansion con- trol and hot property retention, 1.0 mass% of microsili- ca is recommended for the castable containing 4 mass% of magnesia.
文摘Three different castables based on the Al_2O_3–MgO –CaO system were prepared as steel-ladle purging plug refractories： corundum-based low-cement castable（C-LCC）, corundum-spinel-based low-cement castable（C-S-LCC）, and corundum-spinel no-cement castable（C-S-NCC）（hydratable alumina（ρ-Al_2O_3） bonded）. The fracture behavior at room temperature was tested by the method of ＂wedge-splitting＂ on samples pre-fired at different temperatures; the specific fracture energy G′f and notched tensile strength σNT were obtained from these tests. In addition, the Young＇s modulus E was measured by the method of resonance frequency of damping analysis（RFDA）. The thermal stress resistance parameter R′′′′ calculated using the values of G′f, σNT, and E was used to evaluate the thermal shock resistance of the materials. According to the microstructure analysis results, the sintering effect and the bonding type of the matrix material were different among these three castables, which explains their different fracture behaviors.
文摘Al2O3 -MgO castables have been widely used for working linings of steel ladle due to their superior hot strength and corrosion resistance. In this- work, effects of＂ microsilica, ultrafine alumina and MgO fines additions on the rh, eological behavior of the castables were investi- gated by means of IBB rheometer V1. 0 to measure torque （shear stress） under varying shear rates. The re- sults show that rheological properties of castables at varying shear rates are significantly improved with increase of microsilica additions （from 1 mass% to 5 mass% ） and corresponding decrease in water addition; there is only little change in rheological behavior with variation of ultrafine alumina and MgO fines additions. Optimum ultrafine alumina and microsilica additions are recommended for castables with good rheological behavior.
