Microstructures and Corrosion Resistance of Al2O3—C Based Refractories to the Melts Containing Titania

The corrosion resisance of the Al2O3-C based refrac-tories in melts containing titania has been studied by quasi-station immersion and rotary immersionThe corrosion rate is decreased with the addition of graphite carbon and ZrO2 in the refractories.The corrosion mehanism of Al2O3-C refractories is the oxidization of graphite carbon by the oxides of the melts and the formation of deteriorate layer,For the Al2O3-C-ZrO2 refractories,the corrosion behavior is due to the interaction between melts and refrac-tories,The new compounds of FeO.SiO2,SiZrO4,Feo.3CaO,2CaO.SiO2 and CaO.SiO2 are formed in the deteriorate layer.     

Al2O3-SiC-C耐火材料抗CaO-SiO2-K2O渣侵蚀性能研究

研究了Al2O3-SiC-C耐火材料的抗CaO-SiO2-K2O渣侵蚀性能,以及添加Cr2O3对Al2O3-SiC-C材料抗渣侵蚀性能的影响.研究结果表明CaO-SiO2-K2O熔渣对Al2O3-SiC-C材料具有明显的侵蚀作用;在Al2O3-SiC-C材料中添加适量的Cr2O3可以有效地抑制CaO-SiO2-K2O熔渣向耐火材料内部的渗透,降低耐火材料的侵蚀速度.     

Reuse and Reproduction of Used Refractories

1 Introduction About9 millions tonnes of refractories are consumed in China annually owing to the rapid development of the metallurgical industry, from which more than 4 million tonnes of used refractories are inevitably generated. Most of used refractori…     

Innovative Lining of Unburnt Al_2O_3-MgO Brick for 300t Steel Ladle in Baosteel

The manufacture of clean steel needs high performance carbon-free bricks for ladle lining.Based on long term application experiences of the prefab Al₂O₃-MgO blocks,unburnt Al₂O₃-MgO brick has been developed by pressing a mix of alumina,spinel and magnesia as major raw materials and Al₂O₃-MgO gel powder as binder.In addition to low open porosity and high strength,the unburnt Al₂O₃-MgO brick shows superior corrosion resistance and thermal shock resistance to the prefab block.Field trials in a 300t steel ladle have indicated the residual lining of unburnt Al₂O₃-MgO bricks showed smooth surface without large spalling and seldom steel infiltration,consequently longer service life than the prefab blocks.The reliable,unburnt Al₂O₃-MgO bricks have more advantages of high efficiency,energy-saving and eco-friendly production.It will be one of the best options for ladle lining in the manufacture of high-purity steel.     

薄板坯连铸用浸入式水口的性能与使用

针对薄板坯连铸用浸入式水口的使用条件,选择了水口不同部位的材质。以板状刚玉、氧化铝粉、锆莫来石、电熔稳定氧化锆、电熔镁砂、天然鳞片状石墨等为原料制备了浸入式水口,重点研究水口本体铝碳材料的抗氧化性能和渣线锆碳材料的抗侵蚀性能,并模拟现场使用条件进行了烘烤试验。结果表明:所研制的水口材料性能完全满足使用要求,烘烤时无氧化和剥落;在薄板坯实际连铸生产条件下,所研制的浸入式水口稳定地实现了24炉连浇,为相关的浸入式水口研究提供了良好的基础。     

A Retrospective Review of Alumina-magnesia-carbon Refractories

The residual expansion of in-situ spinel formation in using of alumina-magnesia-carbon(AMC)bricks monolizes the lining of steel-making ladles with the closure of their joints,which has been an effective solution avoiding washing out of the joints in ladle lining by the reduction of the penetration of liquid slag and molten steel.Alumina-magnesiacarbon refractories are overall reviewed,in terms of major raw materials,thermal evolution,corrosion and oxidation,and thermomechanical behavior,as well as type,addition and fraction of magnesia used.General commercial products contain 5%-10%MgO and 5%-10%C with a certain amount of metallic aluminum powder,which is believed to facilitate spinel formation at early stage of heating-up,although high magnesia containing AMC bricks are studied and used sometimes.With low ratio of Al₂O₃/C=12.9 and the carbon content of 6.4%C,AMC brick exhibits the highest corrosion resistance.It is important to determine the type,addition and fraction of magnesia used in AMC refractories for demonstrating high corrosion resistance and superior thermomechanical behavior.     

两种不同铁水熔蚀炭砖微观结构分析

为提高高炉炭砖的抗铁水熔蚀性,对两种不同铁水熔蚀性炭砖进行了岩相和电子显微镜分析.炭砖的微观结果分析表明,无烟煤基质的炭砖抗铁水熔蚀性优于在原料中添加石墨的炭砖;往基质中加入Al_2O_3可大为改善炭砖的扰铁水熔蚀性;工艺上使Al_2O_3均匀分布是提高炭砖抗铁水熔蚀性的重要措施.     

气化炉用后高铬砖的渣蚀机理

采用扫描电镜和XRD等分析方法,对石油焦气化炉和水煤浆气化炉用后高铬砖及渣蚀试验砖的显微结构进行了观察与分析。根据高铬砖显微结构变化,研究了在不同气化炉内高铬砖受熔渣侵蚀损毁的机理。结果表明:石油焦气化炉用高铬砖中的Cr2O3与熔渣中的V2O5接触反应,在低温下形成液相而被熔蚀,是其蚀损的主要原因;水煤浆气化炉用高铬砖蚀损的主要原因是Cr2O3在熔渣里的溶解和ZrO2的熔蚀;LIRR-HK95砖由于成分和结构的优化,抗石油焦渣侵蚀性能好。     

Study on Microstructure and Slag Corrosion Mechanism of High Chrome Bricks for Gasifier

1 Introduction The gasifier like Texaco style is of important tech- nical equipment for ammonia synthesis and production of carbamide, carbinol and ethylene etc. Due to differ- ent energy resource structure, petroleum coke is adopt- ed as rawmaterial in A…     

水煤浆气化炉用Cr2O3-ZrO2-Al2O3砖的蚀变过程

利用扫描电镜及能谱仪对水煤浆气化炉用进口铬锆铝砖的蚀变过程进行了显微观察与分析.结果表明此砖在水煤浆气化炉环境条件下的侵蚀主要由熔渣中的SiO2、CaO和P2O5引起;Cr2O3对这种渣蚀表现出很强的化学惰性,溶蚀很小,其使用过程中的主要变化是高温蒸发和在砖内蚀变液相作用下的溶蚀、溶析;而氧化锆蚀变生成的系列产物不仅在蚀变初期有利于保持砖结构致密,并且对蚀变后期基质连续网络结构的形成和保持也起了重要的作用.     

电沉积镍基和铜基纳米复合镀层耐蚀性的研究

通过腐蚀浸泡实验、阳极极化曲线和电化学阻抗谱等测定,探讨了Ni-W-(Si3N4,Al2O3)和Cu-(Al2O3,SiO2)纳米复合镀层的耐蚀性能;通过综合分析,对比添加不同柱子所得镀层的性能,直观地得到添加不同粒子的镍基和铜基纳米复合镀层耐蚀性能的差异.结果表明:Ni-W-Si3N4、Ni-W-Al2O3纳米复合镀层致密度较高,耐蚀性能较好,Cu-Al2O3、Cu-SiO2纳米复合镀层耐蚀性能较差.     

Fabrication and Properties of Closed-pore Al_2O_3-based Refractory Aggregates

A novel Al_2O_3-based refractory aggregate with closed-pore structure was fabricated utilizing superplasticity with submicro-sized Al_2O_3 and MgO as raw materials,and SiC as a high temperature pore-forming agent.The effect of MgO on porosity,phase composition and microstructure of the refractory aggregate has been investigated. For comparison,the common Al_2O_3-based refractory aggregates and porous ones with open-pore structure were also prepared. The results indicate that the closed porosity of Al_2O_3-based refractory aggregate increases as the content of MgO increases. When the content of MgO is 15 mass%,the closed and apparent porosities are 14. 5% and 1. 1%,respectively. The main phase compositions are Al_2O_3 and MgAl_2O_4. The formation mechanism of closed pores is that the fine-crystallinegrain Al_2O_3 ceramic possesses superplastic deformation ability after adding MgO at high temperatures. When SiC powder is added to the Al_2O_3 ceramic,the generated gases by the reaction of SiC at the sintering temperature can provide a pressure to make grain boundaries slide. Then,the gases are enclosed by crystalline grains to form the closed pores. The slag corrosion resistance of the fabricated closed-pore Al_2O_3-based refractory aggregate is better than the common refractory aggregate and porous ones.     

TiO2 在Al2 O3 -SiO2 系耐火材料中的作用

阐述了TiO2在Al2O3-SiO2系耐火材料,特别是高铝矾土中的分布和存在方式,并通过分析Al2O3-SiO2系耐火原料的煅烧过程和Al2O3-SiO2系制品的使用过程中TiO2、Al2O3和SiO2三者之间的化学反应,介绍了TiO2对Al2O3-SiO2系耐火材料结构和性能的影响。     

Corrosion mechanism of magnesia-chrome refractory bricks with FetO-SiO2-Cr2O3 copper converter slag

The paper investigates the effect of Cr₂O₃ on the resistance of magnesia-chrome refractory bricks to copper converter slag. The static crucible method was employed to carry out the slag resistance experiment. The corrosion of magnesia-chrome refractory bricks under the action of Fe_tO-SiO₂-xCr₂O₃ (x = 0–5 wt%) slag at 1300 °C was discussed. The microstructure of the corroded sample was analyzed by XRD and SEM-EDS to elucidate the corrosion mechanisms of magnesia-chrome refractory bricks with Fe_tO-SiO₂-Cr₂O₃ slag. The results indicated that the permeability index of the slag-resistant samples gradually decreased with increasing Cr₂O₃ content in the Fe_tO-SiO₂-Cr₂O₃ slag. Combined with SEM and XRD characterization, the MgO in the refractory reacted with FeO and SiO₂ in the molten slag, leading to dissolution and reaction corrosion of the refractories. Meanwhile, forming a (Mg, Fe)O solid solution layer in corroded samples can prevent further chemical reactions and high-temperature dissolution between the Fe_tO-SiO₂-Cr₂O₃ slag and refractories. With the addition of Cr₂O₃ in the Fe_tO-SiO₂-Cr₂O₃ slag, the corrosion effect of slag on refractories was weakened, and the (Mg, Fe)O solid solution layer became thinner. The magnesia-chrome refractory bricks showed excellent slag resistance when the Cr₂O₃ content in the copper converter slag was 5 wt%.     

α-Al_2O_3微粉对低碳MgO-C材料性能的影响

以电熔镁砂及鳞片石墨为主要原料,热塑性酚醛树脂为结合剂,研究了α-Al_2O_3微粉对低碳MgO-C材料性能的影响.结果表明:(1)Al_2O_3微粉的加入提高了低碳MgO-C材料的体积密度,降低了显气孔率,提高了强度,显著改善了MgO-C砖的抗氧化性;(2)高温下Al_2O_3微粉与MgO原位反应生成连续的尖晶石相,改善了材料基质的显微结构,增强了陶瓷结合,将MgO颗粒与鳞片石墨紧密地结合起来,提高了组织结构的整体性,从而提高了材料的致密度和强度;(3)高温下原位反应生成连续的尖晶石相堵塞脱碳层中的部分气孔,降低了氧的扩散速度,同时提高了MgO的沉积速度,使加入Al_2O_3微粉的低碳MgO-C材料抗氧化性能得以提高.     

Effect of Al_2O_3-ZrO_2 Composite Powder on Thermal Shock Resistance of ZrO_2 Sizing Nozzles

ZrO_2 sizing nozzles with a basic formulation were prepared using 45%( by mass,the same hereinafter)( Mg,Y)- PSZ aggregate,55%( Mg,Y)- PSZ fines and 5% PVA binder. Al_2O_3-ZrO_2 composite powders( 3%,6%,9% and 12%) prepared by sol- gel method were added to replace the equal amount of( Mg,Y)- PSZ fines. Effects of Al_2O_3- ZrO_2 composite powders on physical properties,phase composition and microstructure of the ZrO_2 sizing nozzles were studied.The results show that: the performances of the modified sizing nozzles with 3% Al_2O_3-ZrO_2 composite powder are better than those of the nozzles without composite powder used in current production process,and the thermal shock resistance of the former nozzles is six times of that of the latter one.     

Effects of Firing and Operating Atmospheres on Microstructure and Properties of Phosphate Bonded Cr_2O_3-Al_2O_3-ZrO_2 Bricks

The microstructure and properties of phosphate bonded Cr_2O_3-Al_2O_3-ZrO_2 specimens fired in air or coke bed were investigated firstly. Then property change of the Cr_2O_3-Al_2O_3-ZrO_2 bricks after secondary treatment in simulation environment was studied. Finally,corrosion resistances of the Cr_2O_3-Al_2O_3-ZrO_2 bricks in air and simulation environment were compared; and microstructure of on-site used Cr_2O_3-Al_2O_3-ZrO_2 bricks in slagging gasifiers was analyzed. The results show that the atmosphere has significant effect on the microstructure and properties of the phosphate bonded Cr_2O_3-Al_2O_3-ZrO_2 bricks. As the specimens are fired in air,the phosphate forms a composite solid solution with Cr_2O_3 and Al_2O_3,therefore,strength of the specimens is enhanced. For specimens fired in coke bed,a certain amount of gases are generated owing to the reduction of phosphate and part of Cr_2O_3,which results in the increasing number and size of the pores,bad interfacial bonding between Cr_2O_3 aggregates and matrix as well as low strength of the specimens. During service process in reducing atmosphere,the phosphate binder and part of Cr_2O_3 in edge of the specimens are also reduced,leading to significant increase of number and size of the pores in the edge of the specimens; as a result,inreducing atmosphere,the specimens show much worse corrosion resistance than in air.     

Enhanced corrosion resistance of magnesia-chrome refractories impregnated with zirconia sol

In order to enhance the corrosion resistance to molten vanadates and silicates of middle and upper checker bricks in glass furnace regenerator with petroleum coke as fuel, the present research improved the microstructure, compactness and corrosion resistance of magnesia-chrome refractories by vacuum impregnation with zirconia sol. The results show that the vacuum impregnation of zirconia sol and the increased impregnation times led to the significant increase in the bulk density and decrease in the apparent porosity of refractories, and the impregnated zirconia particles enhanced the corrosion and penetration resistance. The penetrated zirconia particles in the pores decreased the porosity and pore size of refractories, resulting in the inhibited penetration of vanadate and silicate liquid phases during the corrosion process. In addition, the zirconia particles around periclase particles also prevented the reaction between molten corrosion reagent and periclase, thus enhancing the corrosion resistance of refractories. The present study provides an effective method for improving the corrosion resistance of magnesia-chrome checker bricks in regenerator of glass furnace with petroleum coke as fuel.     

Al2O3在莫来石中固溶对ZTM/Al2O3陶瓷结构与性能的影响

研究了加入氧化铝对ZTM陶瓷结构和性能的影响.发现在烧结过程,氧化铝可固溶于莫来石颗粒形成富铝型柱状莫来石,并因其产生的体积膨胀增强了基质对氧化锆颗粒的约束,使材料中的四方氧化锆相对含量增加,其强韧化效果进一步发挥,明显改善了材料的力学性能.     

液相烧结氧化铝和氧化钇稳定四方氧化锆复相材料的显微结构与力学性能

以TiO2，MnO2及CaO—Al2O3-SiO2玻璃为烧结助剂，利用液相烧结法制备了氧化铝和3％氧化钇稳定四方氧化锆复相材料。研究了烧结助荆对材料致密化、显微结构及力学性能的影响。结果表明：除TiO2可与ZrO2晶粒形成部分固溶外，烧结助剂主要以晶间玻璃相的形式存在，并影响了Y2P3在ZrO2晶粒中的分布。烧结助荆的引入显著促进材料的致密化，降低了烧结温度，使材料具有细晶结构，因而具有良好的力学性能。