查看更多>>摘要：The rapid development of iron and steel metallurgy technology has promoted the continuous innovation and iteration of carbon-containing refractories for clean steel smelting.To meet the high-quality requirements for clean steel production and full exploit the performance advantages of carbon-containing refractories in dynamic smelting environment,it is necessary to explore the role of graphite and modified graphite in carbon-containing refractories.Based on this,graphite surface mod-ification methods,including surfactants,surface oxidation,and surface coating,and their applications in carbon-containing refractories are reviewed.The advantages and disadvantages of each method are analyzed for practical use.Furthermore,combined with the existing problems,the application prospect of improved graphite in carbon-containing refractories is discussed.
查看更多>>摘要：Slag corrosion is one of the main factors of the damage of refractory,and its primary manifestations involve the melting of refractory in slag and the slag penetration into refractory,both of which are highly related to the wetting behavior between slag and refractory.The high-temperature wettability could be characterized by parameters including the surface tension,adhesion work,and spreading coefficient of the slag on refractory surface,and it could be suppressed by altering the slag/refractory interface,thus resulting in an improved anti-corrosion performance.From this,the key knowledges of the slag corrosion,theory of wetting behavior and test of high-temperature contact angle were firstly summarized.Then,the major factors influencing the high-temperature slag wetting behavior were discussed based on the aspects of slag composition,refractory composition,and surface microstructure.Finally,the future research direction was proposed in this field.
查看更多>>摘要：Lightweight refractories for the working lining of high-temperature furnaces play an important role in the smelting of advanced steels and superalloys.To prepare lightweight refractories for the working lining of high-temperature furnaces,the synthesis of lightweight aggregates is the basis.Recently,the research on the synthesis of lightweight aggregates with high service temperature,low thermal conductivity,high strength,and good slag resistance has received widespread attention.The available literature on the synthesis of lightweight aggregates was summarized,including corundum,mullite,mullite-corundum,spinel,corundum-spinel,cordierite,cordierite-mullite,calcium hexaluminate,corundum-calcium hexaluminate,bauxite,magnesia,magnesia-based,and forsterite-based aggregates.Finally,the future development trend of lightweight aggregates was proposed.
查看更多>>摘要：The service life of a blast furnace depends largely on the degree of damage to the carbon brick in the hearth.Carbon brick and ramming material in the hearth of a 1780 m3 blast furnace after shutdown were sampled and investigated.It was found that the substances in the cracks of the carbon brick near and above the taphole were ZnO and Zn2SiO4,whereas the substances in the cracks of the carbon brick below the taphole were ZnS.The reaction of Zn with CO,SiO2,and FeS generates ZnO,Zn2SiO4,and ZnS,resulting in volume expansion,which is an important reason for the cracking of carbon brick.Simultaneously,several obvious Zn vapor flow channels were found in the ramming material,through which Zn vapor could enter the carbon brick,causing damage to the carbon brick.Increasing the compactness of the ramming material is beneficial to preventing Zn vapor from entering the carbon brick through the voids in the ramming material,reducing the destructive effect of Zn on the carbon brick and further extending the service life of the blast furnace.
查看更多>>摘要：High alumina slag will cause severe corrosion at the interface of alumina refractory,and the wetting behavior of slag is a key factor influencing the corrosion resistance of refractory ceramics.The static magnetic field is a promising solution for improvement in the slag resistance of refractory.The wetting of alumina refractory ceramics with different basicities of high alumina slags under a weak static magnetic field was analyzed,given that a weak static magnetic field can affect the corrosion behavior of refractory ceramics.Taking slag S3 as an example,when there was an external static magnetic field of 1.0 mT at 1600 ℃,the thickness of calcium aluminate reaction layer at the interface decreased by 36.7％,the denting depth of interface decreased by 35.6％,and the apparent wetting angle increased by 20％.The living radicals and their formation path in oxide melts were verified by first-principles calculation combined with electron paramagnetic resonance spectroscopy analysis.The influence of the flux density of a weak static magnetic field on the wetting behavior of slags was also explored.The contact angle of the slags increased owing to the inhibitory effect of magnetic field on the radical-involved reaction at the interface of the slag and the alumina refractory ceramic.The relationships between the magnetic flux density,diffusion coefficient,slag microstructure(hyperfine coupling constant),and contact angle were established.This provides a theoretical basis for the field control of radical involved reactive wetting between inorganic oxide slags and solid oxide ceramics.
查看更多>>摘要：In order to further promote the application of SiC refractories in modern steel metallurgy,the occurrence forms and formation mechanism of impurities in SiC crystals smelted by Acheson process were investigated.The techniques of inductively coupled plasma-atomic emission spectrometry,X-ray diffraction,and scanning electron microscopy were combined to examine the types and occurrence forms of impurities in smelted SiC crystals.The results showed that the main impurities in the SiC are free Si,free C,oxides(CaO·Al2O3·2SiO2,3Al2O3·2SiO2,CaO·SiO2 and SiO2)and alloy phases(FexSiy,FexSiyTiz and FexAlySiz).The formation process of impurities during the smelting of SiC can be described as follows:At high temperature,the SiO2 and Fe,Ti related oxide impurities present in the raw materials are reduced to Si,Fe,and Ti metal melts.After the reduction process,the free Si,FexSiy and FexSiyTiz are precipitated from the melt during cooling.Free Si primarily exists in aggregated form within the SiC crystal,while the alloy phase is predominantly found at the interface between SiC and free Si,with FexSiyTiz embedded within FexSiy.Towards the end of the cooling process,other impurity oxides such as Al2O3,CaO,and some unreduced SiO2 solidify to form calcium-aluminum-silicate glass phases,predominantly located between SiC grains.The remaining C from the reaction is mainly dispersed as free C within the SiC crystal and at the interface between SiC and free Si.
查看更多>>摘要：The titanium alloys with highly chemical activity require stable crucible refractories that can withstand the erosion of alloy melts.The phase composition and microstructure are crucial factors that affect the stability of the refractory crucible.The effect of Y2O3 on the composition and micro structure of BaZrO3 crucible was systematically investigated,and the improved mechanism of the stability of BaZrO3/Y2O3 crucible was clarified in comparison with the BaZrO3 crucible.The results showed that the erosion layer thickness of the BaZrO3/Y2O3 crucible was only 63 μm,which was far less than that in the BaZrO3 crucible(485 μm),and the erosion layer in the BaZrO3/Y2O3 crucible also exhibited a higher density than that in the BaZrO3 crucible.During the sintering,Y2O3 could improve the densification of the BaZrO3 crucible due to the solid solution effect between Y2O3 and ZrO2,which also caused the evaporation of BaO,resulting in the generation of a Y2O3(ZrO2)film on the surface of the crucible.Furthermore,the Y2O3(ZrO2)had higher thermodynamic stability than Y2O3,confirming that the BaZrO3/Y2O3 crucible with high density exhibited a superior erosion resistance to titanium alloys.This dual-phase structure provides a strategy to design a long-life and stable refractory for melting titanium alloys.
查看更多>>摘要：To understand the mechanism of the interfacial reaction between high-Mn and high-Al steel and MgO refractory,a series of laboratory experiments as well as thermodynamic calculations were performed.The effects of Mn and Al contents in the steel and the reaction time on the interfacial reaction were investigated.It was observed that the erosion of the MgO refractory is caused by the reaction of Al and Mn in the steel with MgO in the refractory,which would lead to the formation of(Mn,Mg)O·Al2O3 spinel and(Mn,Mg)O solid solution.The formation mechanism of the spinel and solid solution is as follows.The Al in the steel firstly reacts with MgO in the refractory to generate MgO·Al2O3 spinel,and then,the spinel reacts with Mn in the steel to form(Mn,Mg)O·Al2O3 spinel.Finally,the MnO in the spinel reacts with the MgO in the inner refractory to form(Mn,Mg)O solid solution.In addition,only(Mn,Mg)O·Al2O3 spinel is present in the interfacial reaction layer of the refractory when the Al content in the steel is sufficient.
查看更多>>摘要：The sodium smelting of vanadium-titanium magnetite can achieve the comprehensive utilization of Fe,V,and Ti.However,the generation of alkaline slag during this process may cause damage to refractory materials.The wettability and corrosion behavior of alkaline slag on three types of refractory(MgO-C,SiC,and high alumina refractory)substrates were investigated at temperatures up to 1200 ℃.The effects of duration on the wettability of molten slag on SiC substrates were also investigated.Results showed that the high alumina refractory exhibited better wettability with the molten slag than the others,and thus,it is easier to be corroded.The results of scanning electron microscopy coupled with energy dispersive spectroscopy showed that MgO-C and high alumina refractory substrates were severely eroded.There was a visible and regular interfacial reaction layer between the slag and SiC refractory substrate,which was produced by the redox reaction between the metal oxides in the slag and the SiC refractory substrate.With the increase in holding time,the interface layer expands and silico-ferrite phases are generated at the interface.The redox reaction between Fe2O3 and SiC substrate is the main reason for the corrosion.By comparing the differences in wettability and corrosion behavior between the alkaline slag from sodium smelting of vanadium-titanium magnetite and MgO-C,SiC and high alumina refractories,it is concluded that SiC refractory has good corrosion resistance to the slag.Iron oxides in the slag accelerate the oxidation rate of SiC refractory.
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