Methods to Characterize Oxidation Resistance for Magnesia—carbon Refractories

The parameters influencing the process of carbon oxidation in magnesia-carbon refracto-ries are reviewed.A typology of their oxidation resistance measurements is then presented;four different method are discussed in details.No agreement has been reached yet on a standard-ized test method.So far,oxidation resistance describes a process more than a property.     

Corrosion Resistance of High-Alumina Graphite Based Refractories to the Smelting Reduction Melts

1 Introduction The corrosion resistance of the refractories is one of the imperative problems for the development of smel- ting reduction with iron bath[1 ~4]. The Al2O3-C based refractories have been widely and successfully used in the metallurgy industr…     

The Effects of Non—Metal Additives on Hydration Reisitance of MgO—C Bricks

The general method of solving the problem of hydration of MgO-C brick is by adding with metal Si,Mg or compround metal additives,but metal additives have bad effect on the MgO-C brick,The test tried adding non-metal additives to matrix material.The results showed that a suitable amount of this kind of additives not only inhibits hydration of MgO-C brick and does not affect corrosion resistance and avoids thermal expansion,but also can improve oxidation resistance.     

Effect of Additives on Properties of MgO—ZrO2—C Material

The paper describes the effect of additives Al,Si,SiC and A4C on the expanson of MgO-ZrO2-C material after being coked.Theresults indicate that Al and Si were oxi-dized to form Al2O3 and SiO2 respectively,and then re-acted with CaZrO3 or stabilizer in c-ZrO2 to form calcium aluminate,spinel(MA),dicalcium silicate(C2S) and forsterite (M2S) ,Meznwhile,α-C2S ras transformed to γ-C2S and c-ZrO2 to m-ZrO2 when temperature changed.All the above reactions resulted in the decrease of the amount of Al4C3 and SiC and the increase in bulk volume,which caused the stucture of MgO-ZrO2-C material de-stroyed.Hence,contrary to the MgO-C material,when adding Al,and Si,the MgO-ZrO2-C material would be structurally deteriorated after heat-treatment and its strength and corrosion resistance decreased.     

Effect of ZrO2 Additives on the Thermal Shock Resistance of MgO—MA Refractory

The additirn of three kins ZrO2-bearing additives into MgO-MA refractory could all increase the latter‘s C.C.S.and the thermal shock resistance,XRD,polarizing microscope and electron probe analysis were used to analyze the mechanism to improve the thermal shock resistance of the material.The mechanism is that ZrO added into the material improves the microstructure,introduces asppropriate micro cracks into matrix ,enhances the matrix,and therefore increases the thermal shock resistance of ther refractory.     

Effect of Metallic Zn Powder on Oxidation Resistance of Al2O3 -C Refractories

1 IntroductionCharacterized by excellent thermal shock resist-ance, slag erosion resistance, Al2O3-C refractory hasalready been widely used as some functional parts forcontinuous casting system, such as slide plate, nozzleand so on. However, during the ap…     

A Study on Corrosion Behavior of Al2O3—C—ZrO2 Refactory in Melts of Smelting Reduction with Iron Bath

The corrosion behavor and corrosion rate of Al2O3-C-ZrO2 serial refractories in mets of smelting reduction have been studied with rotary immersion and static immersion test.The main factors that affet the interaction between melts and refractory were also investigated.The results showed that the corrosion rate of Al2O3-C-ZrO2 serial refractories is decreased with the ZrO2 content increasing when ZrO2 content is in the range of 3% to 10%,FeO content in mets,rotary speed and temperature are the main factors in melts,rotary speed and temperature are the main factors affecting corrosion rate.According to the test resuts,Al2O3-C-ZrO2 serial refractories are difficult to be directly used as the lining materials in molten bath of smelting reducion with iron bath.     

Effects of Additives on Properties of Unburned MgO—Al2O3 Refractory

The influences of four kinds of additives added into the matrix of MgO-Al2O3 unbuned products were investigated,The results show that samples with proper MgO/Al2O3 ration and proper addition of Cr2O3(2%- 4%) have good thermal shock resistance and slag corrosion resistance as well,XRD and SEM determination results indicate that a kind of compound spinel(Mg,Al, Cr) O4 was formed and the microstucture of the samples are denser.     

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.     

The Microstructure and Oxidation Resistance of Resion—Besed Carbon

The structure and oxidation resistance of five kinds of phenol formaldehyde resin-based carbons have been studied.The effects of heating treatment conditions(HTC) of the resins on the crystal structure and microstructure have been investigated,and the relationships between structure and oxidation resistance of the carbon have also been investigated.The results indicated that the HTC have great influence on the microstructure,but little effet can be found on the crystal structure of the carbons,It is found micropore model of the carbon accords with the parallel palne model.The research results also indicated that the oxidtion resistance of the carbons is strongly depended on the factors such as speific surface area,micropore distribution,opening micropore volume etc,the crystal struce-ture has little effect on the oxidation resistance of the carbon.     

Influence of Special Silica on the In—Situ Growth of Silicon Carbide Whiskers in Al2O3—C Refractories

In this paper,the influence of special silicas on the in-situ growth of silicon carbide whiskers in Al2O3-C refractories has been stud-ied.The microstructures of the products have been analyzed by means of SEM,and it is found that the whiskers grew better by adding some special silicas,Silica ② shows the best result because the VLS mechanism made the whiskers grow as long as 40μm and could be expected to greatly improve the mechnical properties of the refractories.     

Effects of Refractories on the Total Oxygen Content and Inclusions in the IF Steel

The effects of refractories of quarz-corundum consisting of 45 mass% quartz and 55 mass% corundum,fused corundum and fused magnesia on the total axygen content(TOC) and the composition of inclusions in intersitital free(IF) steel were studied,3 mass% microsilica was added into the three refractories as binder.The refractories were shaped as lining of the graphite crucible by castable method IF steel was placed in the crucibles,then they were heated at 1600℃ for 90min and 45min respectively.Oxygen contents of the steel samples were obtained by axygen determinator.Inclusions were analyzed by SEM and EDS.The results show that the TOC of steel increase with ncrease of Index of Oxygen Potetial (IOP) of the refractories.The steel sample coped with MgO refractories having the lowest IOP has the lowest TOC.     

Influence of Ultra-Fine B4C and Nano-SiO2 on the Properties of Alumina-Graphite Refractories

The role of nano-SiO2 and ultra-fine boron carbide on the properties of alumina-graphite materials was investigated.The study showed that the ultra-fine boron carbide added modified the microstructure of residual carbon and promoted the chemical bond between residual carbon from phenolic resin and flake graphite.The carbon white could strengthen the residual carbon from phenolic resin.These two additives improved the mechanical properties of AG refractories at both room temperature and high temperature,and thermal shock resistance was improved noticeably.When the two additives were doped together,carbon white could retard the evaporation of B2O3.Thermal shock resistance was guaranteed with a smaller amount of ultrafine born carbide.     

Physical Properties and Hydration Resistance of CeO2—and CeO2／Fe2O3—Bearing Dolomite Refractory Products

Dolomite refractory products with excellent hydration resistance have been produced by using CeO2-and CeO2/Fe2O3-bearing dolomite clinkers,Their physical properties as well as hydration resistance have been investigated,The addition of CeO2 has little harmful effect on the high temperature properties of dolomite refractory products such as hot MOR and slag resistance,And the shelf lives of the dolomite refractory products containing CeO2 and CeO2/Fe2O3 additions at the same condition are two times that of the common dolomite refractory produt.The dolomite refractory product containing CeO2/Fe2O3 combination possesses the best hydration resistance,but gives poor slag resistance.     

Effect of Sintering Additives on the Nitridation and Densification Behavior of Si—SiC Composite

Most of the thermo-mechanical properties of reaction bonded silicon nitride,including a second phase such as SiC depend on the final denstiy and the grain boundary glass phase of the sintered material .Thus it is necessary to know the sintering aid system most effective for the Si0-SiC compostie system ,Sintering experiments carried out using different combinations of sintering aids has indicated that two combinations,i.e.,(a) yttria with alumina and (b) yttia with aluminium nitride are effective sintering aid systems for the reation bonded Si-SiC composites.Adensity of 98.5% theoretical was obtained with yttria and aluminium nitride system.     

The Behavior of Refractory Slab——A Primary Discussion on the Correlation of Essential Factors and their Effects

The interrelation of various factors affecting the mechanical strength ,the thermal shock resistivity and creep deformation of slab in a simple setting condition of the firing of table ware are discussed,The conrol of parameters in favour of the desired performance of the slab is propsed.