The corundum - spinel castables were prepared by six kinds of tabular corundum, as aggregates, respective- ly, and their linear change rate on heating, apparent porosity, bulk density, cold modulus of rupture, coht cr...The corundum - spinel castables were prepared by six kinds of tabular corundum, as aggregates, respective- ly, and their linear change rate on heating, apparent porosity, bulk density, cold modulus of rupture, coht crushing strength, hot modulus of rupture and thermal shock resistance were compared and studied. The results show that： 1） the six tabular corundum materials have similar main chemical composition but their physical properties vary for the different technical procedures which result in different properties of castables ; 2 ） the optimal properties of corundum - spinel castables corre- spotut to different tabular corundum types, so the corundum type shall be selected according to the application of the castables.展开更多
Purging plugs installed in the bottom of steel ladles are widely used for the secondary refining of high quality steel grades.The dynamic service conditions and temperature gradients caused by the cold inert gas blown...Purging plugs installed in the bottom of steel ladles are widely used for the secondary refining of high quality steel grades.The dynamic service conditions and temperature gradients caused by the cold inert gas blown through the plug during stirring create a strong thermal shock impact on the materials.This can affect its service life and restrict the safety and efficiency of steel making if the plug fails during use.In this work,the influence of the particle size distribution (PSD) and amount of reactive alumina on the sintering behavior of ultra-low cement bonded corundum-spinel based castables was investigated on lab scale.The relationship between sintering reactivity of matrix and thermal shock resistance of castables was evaluated in detail.Results show that the sintering of castables can be intensified by using finer reactive alumina.However,excessive sintering of the castable through finer reactive alumina is negative for thermal shock resistance.The microstructure characterization reveals that castables with more intense sintering show denser matrix structure,which is less effective in hampering crack propagation and therefore results in decline of their thermal shock resistance.展开更多
Five lightweight castables containing different TiO2 additions were prepared by using porous corundum - spinel （ MgAl2O4 ） ceramics as aggregate. Corrosion of the lightweight cstables by ladle slag was conducted u...Five lightweight castables containing different TiO2 additions were prepared by using porous corundum - spinel （ MgAl2O4 ） ceramics as aggregate. Corrosion of the lightweight cstables by ladle slag was conducted using a static crucible test. The effect of the TiO2 addition on the slag resistances of the lightweight corundum -spinel castables was investigated through SEM, EDS and Fact- Sage@ software, etc. h was found that TiO2 additi,ve t,vmoted the sintering degree of the castables, deereased the average pore .size, the apparent porosity, and the contact area between the casmbles and slag, and then en- hanced the corrosion resistance. However, TiO2 additive decreased the viscosity of the penetrated .slag simultane- ously, and then deteriorated the penetration resistance.展开更多
Corundum -spinel castables containing lightweight aggregates have drawn many attentions due to their po- tential for energy-saving, especially when applied in the high-temperature region, such as the work lining of re...Corundum -spinel castables containing lightweight aggregates have drawn many attentions due to their po- tential for energy-saving, especially when applied in the high-temperature region, such as the work lining of refi- ning ladle. One main aspect that restricts their applica- tion is the slag corrosion performance. In this study, one dense tabular corundum and three kinds of lightweight corundum were chosen as aggregates to prepare four dif- ferent corundum - spinel castables. The slag resistance was compared through the induction furnace corrosion test. SEM - EDS, XRD, and thermodynamic and kinet- ics analysis were adopted for the discussion of the corro- sion mechanism. Results show that the crystal grain size and shape of aggregates are important for the slag corro- sion resistance of lightweight corundum -spinel castables under dynamic condition （enforced convection） , yet the effects of pore characteristics are not dominated. Aggre- gates with large flake-like crystal grains show a thicker dissolution diffusion boundary layer and a lower dissolution rate, resulting in a favorable corrosion resist- ance of the castable. The poor microstructure of the ag- gregates, namely, larger pores and small and spherical grains, would cause deterioration of castables＇ slag resistance.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
A1203-SiC-C iron trough castables were prepared using high alumina bauxite clinker GL-90 （ 〉 1 mm ） or homogenized bauxite GL-88 to replace the traditional brown corundum aggregates （ 〉 1 mm ） to reduce the cost...A1203-SiC-C iron trough castables were prepared using high alumina bauxite clinker GL-90 （ 〉 1 mm ） or homogenized bauxite GL-88 to replace the traditional brown corundum aggregates （ 〉 1 mm ） to reduce the cost of iron trough castables. Effects of the two bauxite aggregates on properties of iron trough eastables were investigated. The results show that the two kinds of bauxite affect flowability, bulk density, strength and slag corrosion resistance of trough castables differently. Compared with homogenized bauxite, high alumina bauxite clinker is more suitable to substitute brown corundum. The castables prepared from the bauxite clinker have similar performances with those prepared from brown corundum, especially used in medium or small blast furnaces with weak thermal impact and lower temperature hot metal. However, in large blast furnaces with severe thermal impact and high temperature hot metal, the performances of the two castables are significantly different. So it is suggested to use the brown corundum based castables in the front gyral zone of the slag skimmer.展开更多
Al2O3-SiC-C castables for iron trough with fused magnesia powder （0, 3%, 6%, 9% and 12%） were prepared with brown fused corundum particles （5-3mm, 3-1mm, ≤1mm）, white fused corundum powder （≤0.088mm）, SiC part...Al2O3-SiC-C castables for iron trough with fused magnesia powder （0, 3%, 6%, 9% and 12%） were prepared with brown fused corundum particles （5-3mm, 3-1mm, ≤1mm）, white fused corundum powder （≤0.088mm）, SiC particle （≤1mm） and powder （ ≤0.088mm）, fused magnesia powder （ ≤0. 088mm）, reactive α-Al2O3 micropowder, ultrafine SiO2 , Si powder and sphere pitch as main starting materials and calcium aluminate cement as binder. The specimens were fired at 1100℃ and 1450℃ for 3 h after vibrating moulding, curing, demoulding and drying at 110℃ for 24 h. Bulk density, apparent porosity, linear change rate, modulus of rupture, resistance to blast furnace slag, oxidation resistance, phase composition and microstructure of the specimens were analyzed. The results show that： （1） With fused magnesia addition increasing, apparent porosity increases, while bulk density, modulus of rupture and oxidation resistance decline, slag resistance varies slightly; （2） The main crystal phases in the specimens fired at 1450℃ for 3 h are 3C-SiC, 6H-SiC, corundum, periclase, reaction-synthesized spinel and mullite; the quantity of the formed spinel and mullite increases with the increase of fuzed magnesite addition; （3） Along the corroded side, spinel layer with about 80μm thickness forms at the co- rundum particles boundary.展开更多
Three different kinds of corundum aggregates-tabular sintered alumina, dense sintered alumina, and fused dense corundum-were introduced into the silica fume .free or silica fume containing Al2O3 -SiC - C iron runner c...Three different kinds of corundum aggregates-tabular sintered alumina, dense sintered alumina, and fused dense corundum-were introduced into the silica fume .free or silica fume containing Al2O3 -SiC - C iron runner castables to investigate their influences on the flow ability, linear change on heating, bulk density, apparent porosity, cold strength, hot modulus of rupture, therm, al shock resistance, slag resistance, oxidation resistance as well as wear resistance of Al2O3 - SiC - C iron runner castables. The results show that （ 1 ） compared with the specimens with fused dense corundum, the specimens with dense sintered alumina have equivalent installation property, slag resistance and oxidation resistance, equivalent or even higher cold modulus of rupture, cold crushing strength and hot modulus of rupture, exhibiting better thermal shock resistance and cold wear resistance ; （2） adopting bimodal alumina micropowder LISAL22RABL as well as water reducers ZX2 and ZD2 can well reduce the water requirement of silica fume free castables, solving the problem of deteriorated flow ability resulted from the lack of silica fume; since the lack of silica fume avoids the formation of low melting point liquid, the hot modulus of rupture and the thermal shock resistance of the silica fume free castables are both better than those of the silica fume containing castables ; （3） the density of the castable specimens with dense sintered alumina is 4% -6% lower than that of the castable specimens with Jhsed dense corundum so the refractories consumption of one iron runner reduces by 5% by using the tastable with dense sintered alumina, which obviously reduces the cost of refractories.展开更多
文摘The corundum - spinel castables were prepared by six kinds of tabular corundum, as aggregates, respective- ly, and their linear change rate on heating, apparent porosity, bulk density, cold modulus of rupture, coht crushing strength, hot modulus of rupture and thermal shock resistance were compared and studied. The results show that： 1） the six tabular corundum materials have similar main chemical composition but their physical properties vary for the different technical procedures which result in different properties of castables ; 2 ） the optimal properties of corundum - spinel castables corre- spotut to different tabular corundum types, so the corundum type shall be selected according to the application of the castables.
基金the National Natural Science Foundation of China(51572244 and U1604252)for supporting this work
文摘Purging plugs installed in the bottom of steel ladles are widely used for the secondary refining of high quality steel grades.The dynamic service conditions and temperature gradients caused by the cold inert gas blown through the plug during stirring create a strong thermal shock impact on the materials.This can affect its service life and restrict the safety and efficiency of steel making if the plug fails during use.In this work,the influence of the particle size distribution (PSD) and amount of reactive alumina on the sintering behavior of ultra-low cement bonded corundum-spinel based castables was investigated on lab scale.The relationship between sintering reactivity of matrix and thermal shock resistance of castables was evaluated in detail.Results show that the sintering of castables can be intensified by using finer reactive alumina.However,excessive sintering of the castable through finer reactive alumina is negative for thermal shock resistance.The microstructure characterization reveals that castables with more intense sintering show denser matrix structure,which is less effective in hampering crack propagation and therefore results in decline of their thermal shock resistance.
基金The National Natural Science Foundation of China(Grant No.51302201)
文摘Five lightweight castables containing different TiO2 additions were prepared by using porous corundum - spinel （ MgAl2O4 ） ceramics as aggregate. Corrosion of the lightweight cstables by ladle slag was conducted using a static crucible test. The effect of the TiO2 addition on the slag resistances of the lightweight corundum -spinel castables was investigated through SEM, EDS and Fact- Sage@ software, etc. h was found that TiO2 additi,ve t,vmoted the sintering degree of the castables, deereased the average pore .size, the apparent porosity, and the contact area between the casmbles and slag, and then en- hanced the corrosion resistance. However, TiO2 additive decreased the viscosity of the penetrated .slag simultane- ously, and then deteriorated the penetration resistance.
基金The National Natural Science Foundation of China(Grant No.51204126 and No.51474165)
文摘Corundum -spinel castables containing lightweight aggregates have drawn many attentions due to their po- tential for energy-saving, especially when applied in the high-temperature region, such as the work lining of refi- ning ladle. One main aspect that restricts their applica- tion is the slag corrosion performance. In this study, one dense tabular corundum and three kinds of lightweight corundum were chosen as aggregates to prepare four dif- ferent corundum - spinel castables. The slag resistance was compared through the induction furnace corrosion test. SEM - EDS, XRD, and thermodynamic and kinet- ics analysis were adopted for the discussion of the corro- sion mechanism. Results show that the crystal grain size and shape of aggregates are important for the slag corro- sion resistance of lightweight corundum -spinel castables under dynamic condition （enforced convection） , yet the effects of pore characteristics are not dominated. Aggre- gates with large flake-like crystal grains show a thicker dissolution diffusion boundary layer and a lower dissolution rate, resulting in a favorable corrosion resist- ance of the castable. The poor microstructure of the ag- gregates, namely, larger pores and small and spherical grains, would cause deterioration of castables＇ slag resistance.
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A1203-SiC-C iron trough castables were prepared using high alumina bauxite clinker GL-90 （ 〉 1 mm ） or homogenized bauxite GL-88 to replace the traditional brown corundum aggregates （ 〉 1 mm ） to reduce the cost of iron trough castables. Effects of the two bauxite aggregates on properties of iron trough eastables were investigated. The results show that the two kinds of bauxite affect flowability, bulk density, strength and slag corrosion resistance of trough castables differently. Compared with homogenized bauxite, high alumina bauxite clinker is more suitable to substitute brown corundum. The castables prepared from the bauxite clinker have similar performances with those prepared from brown corundum, especially used in medium or small blast furnaces with weak thermal impact and lower temperature hot metal. However, in large blast furnaces with severe thermal impact and high temperature hot metal, the performances of the two castables are significantly different. So it is suggested to use the brown corundum based castables in the front gyral zone of the slag skimmer.
文摘Al2O3-SiC-C castables for iron trough with fused magnesia powder （0, 3%, 6%, 9% and 12%） were prepared with brown fused corundum particles （5-3mm, 3-1mm, ≤1mm）, white fused corundum powder （≤0.088mm）, SiC particle （≤1mm） and powder （ ≤0.088mm）, fused magnesia powder （ ≤0. 088mm）, reactive α-Al2O3 micropowder, ultrafine SiO2 , Si powder and sphere pitch as main starting materials and calcium aluminate cement as binder. The specimens were fired at 1100℃ and 1450℃ for 3 h after vibrating moulding, curing, demoulding and drying at 110℃ for 24 h. Bulk density, apparent porosity, linear change rate, modulus of rupture, resistance to blast furnace slag, oxidation resistance, phase composition and microstructure of the specimens were analyzed. The results show that： （1） With fused magnesia addition increasing, apparent porosity increases, while bulk density, modulus of rupture and oxidation resistance decline, slag resistance varies slightly; （2） The main crystal phases in the specimens fired at 1450℃ for 3 h are 3C-SiC, 6H-SiC, corundum, periclase, reaction-synthesized spinel and mullite; the quantity of the formed spinel and mullite increases with the increase of fuzed magnesite addition; （3） Along the corroded side, spinel layer with about 80μm thickness forms at the co- rundum particles boundary.
文摘Three different kinds of corundum aggregates-tabular sintered alumina, dense sintered alumina, and fused dense corundum-were introduced into the silica fume .free or silica fume containing Al2O3 -SiC - C iron runner castables to investigate their influences on the flow ability, linear change on heating, bulk density, apparent porosity, cold strength, hot modulus of rupture, therm, al shock resistance, slag resistance, oxidation resistance as well as wear resistance of Al2O3 - SiC - C iron runner castables. The results show that （ 1 ） compared with the specimens with fused dense corundum, the specimens with dense sintered alumina have equivalent installation property, slag resistance and oxidation resistance, equivalent or even higher cold modulus of rupture, cold crushing strength and hot modulus of rupture, exhibiting better thermal shock resistance and cold wear resistance ; （2） adopting bimodal alumina micropowder LISAL22RABL as well as water reducers ZX2 and ZD2 can well reduce the water requirement of silica fume free castables, solving the problem of deteriorated flow ability resulted from the lack of silica fume; since the lack of silica fume avoids the formation of low melting point liquid, the hot modulus of rupture and the thermal shock resistance of the silica fume free castables are both better than those of the silica fume containing castables ; （3） the density of the castable specimens with dense sintered alumina is 4% -6% lower than that of the castable specimens with Jhsed dense corundum so the refractories consumption of one iron runner reduces by 5% by using the tastable with dense sintered alumina, which obviously reduces the cost of refractories.
