In order to improve oxidation resistance and ther- mal shock resistance of Al2O3-C refractories, two groups of specimens were prepared with phenolic resin as binder, adding 0, 2 wt% , 4 wt% and 6 wt% commercial SiC or...In order to improve oxidation resistance and ther- mal shock resistance of Al2O3-C refractories, two groups of specimens were prepared with phenolic resin as binder, adding 0, 2 wt% , 4 wt% and 6 wt% commercial SiC or ZrO2-SiC composite powder synthesized from zircon respectively to Al2O3- C refractories, pressing at 200 MPa, drying fully at 250℃, and then carbon embedded firing at 1400℃ for 2 h. Oxidation resistance and thermal shock resistance were researched, phase composition was analyzed by XRD. The results showed that the oxidation of SiC in additives could protect carbon in specimens effectively and thus decreased the mass loss ratio and oxidation area, and improved the oxidation resistance of the specimen. Thermal shock resistance was improved owing to the micro crack toughening of ZrO2 and grain toughening of SiC. In this experiment, the specimens with 6 wt% ZrO2 -SiC composite powder or 6 wt% SiC powder had the best oxidation resistance and thermal shock resistance.展开更多
Newly developed Al2O3-Si3N4 composite refractories used for blast furnace is introduced in this work. Al2O3-Si3N4 composite refractories attacked by alkali vapor and blast furnace slag was investigated. High performan...Newly developed Al2O3-Si3N4 composite refractories used for blast furnace is introduced in this work. Al2O3-Si3N4 composite refractories attacked by alkali vapor and blast furnace slag was investigated. High performance Al2O3-Si3N4 composite refractories was produced and used at both 2560m^3 blast furnaces of Tan-gsteel and No. 5 blast furnace of Shaosteel.展开更多
This paper attempts to clarify the systematic works of the refractories for the RH degassers and the ways of improving their lining life. It includes : ( 1 ) types of RH degassers ; (2) the operating conditions o...This paper attempts to clarify the systematic works of the refractories for the RH degassers and the ways of improving their lining life. It includes : ( 1 ) types of RH degassers ; (2) the operating conditions of refining and the severely damaged areas in RH degassers ; (3) the reasons why side wall and bottom of lower vessel, throat and snorkels become the severe wear areas are analyzed, such as erosion and abrasion caused by the high circula- tion rate of treated molten steel, thermal and structural spalling by the violent temperature change, high corrosion by the Fe-oxides containing siliceous slag and CaF:riched desulfurization powders attack, degradation of texture by the vaporization of refractory components in vacuum and in oxygen blowing; besides the above men- tioned factors, what other reasons to make the snorkels become the most quick wear elements are also explained; (4) the studies of resistance to refining slags attack and slag penetration and its prevention ; the evaluation of va- rious refractory materials to withstand the attack of slags is based on the experimental results of rotating cylinder method, rotary drum test and induction furnace test, and the phase diagrams analyses; the measures to reduce the slag penetration are discussed, for example the deep of slag penetration can be decreased by reducing the size of brick pores ; (5) suitable refractory materials selection and recent developments for the different severe wear areas in RH, and lining maintenance; (6) refractories for RH to refine silicon steel; (7) the ways of improving RH lining life.展开更多
The paper analyzed the recycle condition and developing trend of used refractories China and other countries, irwluding research achievements of recycles of used refractories such as MgO-C bricks, Al2O3-MgO-C brics, A...The paper analyzed the recycle condition and developing trend of used refractories China and other countries, irwluding research achievements of recycles of used refractories such as MgO-C bricks, Al2O3-MgO-C brics, Al2O3-SiC-C castable and MgO-Cr2O3 bricks. Recycled refractories exhibit the same or even better properties as compared with the original. In addition, prospects for recycle of used refractories are also discusseded.展开更多
This work explored the way to improve hot modulus q/' rupture (HMOR) and refractoriness under load (RUL) by adding mild-calcined coal gangue (MCG) in Al2O3 -SiO2 ultra low cement (ULC) castables, making use o...This work explored the way to improve hot modulus q/' rupture (HMOR) and refractoriness under load (RUL) by adding mild-calcined coal gangue (MCG) in Al2O3 -SiO2 ultra low cement (ULC) castables, making use of the in-situ effect of the MCG during heating-up. The influence of respective additions of 5%, 10% and 1.5% of the MCG powders calcined at 700℃ was investigated on HMOR at 1400 ℃ and RUL of the castables. With increased addition of the MCG, HMOR and RUL become significantly enhanced. At 10% of the MCG addition, HMOR reaches 3 MPa, as compared to 0. 3 MPa in the case of no MCG addition. RUL of the specimens dried at 110 ℃for 24 h can be increased by some 270 ℃ with 10% of the MCG addition. RUL 0.11 the specimens preheated at 1 500℃ for 3 h maintains the growth trend with the MCG addition increasing. The microstructure of the heated castable samples was investigated by means of SEM. The in-situ formed needle-like and interlaced mullite in the matrix is contributive to the tmprovement.展开更多
The interfacial reactions of Cr2O3- Al2O3 refractory materials with smelting reduction ironmaking slag were investigated by thermodynamic modeling. The calculation results indicated that different spinel phases were p...The interfacial reactions of Cr2O3- Al2O3 refractory materials with smelting reduction ironmaking slag were investigated by thermodynamic modeling. The calculation results indicated that different spinel phases were produced after the interactions between the slag and three types of refractory materials( 10Cr2O3- 90Al2O3,50Cr2O3- 50Al2O3 and 90Cr2O3- 10Al2O3) at 1 500℃. Increased contents of Al2O3 and Cr2O3in the remained liquid slag after interaction implied the dissolution of refractory. Thermodynamic modeling predicted that the process of dissolution might lead to much deeper penetration into the refractory materials by the present compositional slag. Accordingly,corrosion testing was also conducted to validate the thermodynamic prediction.展开更多
Six kinds of Cr2O3 - Al2 O3 fused grains (the mass percent of Cr203 was 15%, 40%, 50%, 60%, 85% and 99%, respectively ) were prepared using chrome green and Al203 powder as starting materials by electro-fnsion, n...Six kinds of Cr2O3 - Al2 O3 fused grains (the mass percent of Cr203 was 15%, 40%, 50%, 60%, 85% and 99%, respectively ) were prepared using chrome green and Al203 powder as starting materials by electro-fnsion, named as CR15, CR40, CR50, CR60, CR85, and CR99, respectively. The corrosion resistance of the six kinds of Cr2O3- Al2O3.fused grains (4-1 ram) was studied using rotary slag corrosion method. The results show that: ( 1 ) the corrosion resistance of the fused grains increases with the Cr203 content and the grain size increasing; (2)the grains of CR99 and CR85 with higher Cr2O3 content are corroded at the slag surJace layer, because FeO and Al2O3. in the slag corrode the grains ; FeO reacts with Cr2O3 in the aggregates.forming (Fe, Cr )3O4 ,spinel firstly, and the spinel reacts with other phases forming composite spinel; when FeO is fidly consumed, Al2 O3 penetrated into the grains reacts with Cr2O3 Jorming Al2O3 - Cr2O3 solid solution on the grains surface; (3) for CR60, the corrosion exists both in the slag surface layer and in the penetration layer; in the penetration layer, CaO and SiO2 react with Al2O3 in Al2O3 - Cr2O3 solid solution forming anorthite , gehlenite ,and glass phase; the grains of CR50, CR40 and CRI5 have the same corrosion mechanism with CR60 in the penetration layer.展开更多
文摘In order to improve oxidation resistance and ther- mal shock resistance of Al2O3-C refractories, two groups of specimens were prepared with phenolic resin as binder, adding 0, 2 wt% , 4 wt% and 6 wt% commercial SiC or ZrO2-SiC composite powder synthesized from zircon respectively to Al2O3- C refractories, pressing at 200 MPa, drying fully at 250℃, and then carbon embedded firing at 1400℃ for 2 h. Oxidation resistance and thermal shock resistance were researched, phase composition was analyzed by XRD. The results showed that the oxidation of SiC in additives could protect carbon in specimens effectively and thus decreased the mass loss ratio and oxidation area, and improved the oxidation resistance of the specimen. Thermal shock resistance was improved owing to the micro crack toughening of ZrO2 and grain toughening of SiC. In this experiment, the specimens with 6 wt% ZrO2 -SiC composite powder or 6 wt% SiC powder had the best oxidation resistance and thermal shock resistance.
文摘Newly developed Al2O3-Si3N4 composite refractories used for blast furnace is introduced in this work. Al2O3-Si3N4 composite refractories attacked by alkali vapor and blast furnace slag was investigated. High performance Al2O3-Si3N4 composite refractories was produced and used at both 2560m^3 blast furnaces of Tan-gsteel and No. 5 blast furnace of Shaosteel.
文摘This paper attempts to clarify the systematic works of the refractories for the RH degassers and the ways of improving their lining life. It includes : ( 1 ) types of RH degassers ; (2) the operating conditions of refining and the severely damaged areas in RH degassers ; (3) the reasons why side wall and bottom of lower vessel, throat and snorkels become the severe wear areas are analyzed, such as erosion and abrasion caused by the high circula- tion rate of treated molten steel, thermal and structural spalling by the violent temperature change, high corrosion by the Fe-oxides containing siliceous slag and CaF:riched desulfurization powders attack, degradation of texture by the vaporization of refractory components in vacuum and in oxygen blowing; besides the above men- tioned factors, what other reasons to make the snorkels become the most quick wear elements are also explained; (4) the studies of resistance to refining slags attack and slag penetration and its prevention ; the evaluation of va- rious refractory materials to withstand the attack of slags is based on the experimental results of rotating cylinder method, rotary drum test and induction furnace test, and the phase diagrams analyses; the measures to reduce the slag penetration are discussed, for example the deep of slag penetration can be decreased by reducing the size of brick pores ; (5) suitable refractory materials selection and recent developments for the different severe wear areas in RH, and lining maintenance; (6) refractories for RH to refine silicon steel; (7) the ways of improving RH lining life.
文摘The paper analyzed the recycle condition and developing trend of used refractories China and other countries, irwluding research achievements of recycles of used refractories such as MgO-C bricks, Al2O3-MgO-C brics, Al2O3-SiC-C castable and MgO-Cr2O3 bricks. Recycled refractories exhibit the same or even better properties as compared with the original. In addition, prospects for recycle of used refractories are also discusseded.
文摘This work explored the way to improve hot modulus q/' rupture (HMOR) and refractoriness under load (RUL) by adding mild-calcined coal gangue (MCG) in Al2O3 -SiO2 ultra low cement (ULC) castables, making use of the in-situ effect of the MCG during heating-up. The influence of respective additions of 5%, 10% and 1.5% of the MCG powders calcined at 700℃ was investigated on HMOR at 1400 ℃ and RUL of the castables. With increased addition of the MCG, HMOR and RUL become significantly enhanced. At 10% of the MCG addition, HMOR reaches 3 MPa, as compared to 0. 3 MPa in the case of no MCG addition. RUL of the specimens dried at 110 ℃for 24 h can be increased by some 270 ℃ with 10% of the MCG addition. RUL 0.11 the specimens preheated at 1 500℃ for 3 h maintains the growth trend with the MCG addition increasing. The microstructure of the heated castable samples was investigated by means of SEM. The in-situ formed needle-like and interlaced mullite in the matrix is contributive to the tmprovement.
基金supported by Preliminary Research Project for National Basic Research Program of China ( 2012CB724607 )
文摘The interfacial reactions of Cr2O3- Al2O3 refractory materials with smelting reduction ironmaking slag were investigated by thermodynamic modeling. The calculation results indicated that different spinel phases were produced after the interactions between the slag and three types of refractory materials( 10Cr2O3- 90Al2O3,50Cr2O3- 50Al2O3 and 90Cr2O3- 10Al2O3) at 1 500℃. Increased contents of Al2O3 and Cr2O3in the remained liquid slag after interaction implied the dissolution of refractory. Thermodynamic modeling predicted that the process of dissolution might lead to much deeper penetration into the refractory materials by the present compositional slag. Accordingly,corrosion testing was also conducted to validate the thermodynamic prediction.
文摘Six kinds of Cr2O3 - Al2 O3 fused grains (the mass percent of Cr203 was 15%, 40%, 50%, 60%, 85% and 99%, respectively ) were prepared using chrome green and Al203 powder as starting materials by electro-fnsion, named as CR15, CR40, CR50, CR60, CR85, and CR99, respectively. The corrosion resistance of the six kinds of Cr2O3- Al2O3.fused grains (4-1 ram) was studied using rotary slag corrosion method. The results show that: ( 1 ) the corrosion resistance of the fused grains increases with the Cr203 content and the grain size increasing; (2)the grains of CR99 and CR85 with higher Cr2O3 content are corroded at the slag surJace layer, because FeO and Al2O3. in the slag corrode the grains ; FeO reacts with Cr2O3 in the aggregates.forming (Fe, Cr )3O4 ,spinel firstly, and the spinel reacts with other phases forming composite spinel; when FeO is fidly consumed, Al2 O3 penetrated into the grains reacts with Cr2O3 Jorming Al2O3 - Cr2O3 solid solution on the grains surface; (3) for CR60, the corrosion exists both in the slag surface layer and in the penetration layer; in the penetration layer, CaO and SiO2 react with Al2O3 in Al2O3 - Cr2O3 solid solution forming anorthite , gehlenite ,and glass phase; the grains of CR50, CR40 and CRI5 have the same corrosion mechanism with CR60 in the penetration layer.