The Study Of The Effect Of Magnesia And Micropowders On The Properties Of No-cement Corundum Spinel Castables

The research object of this article is a kind of no-cement alumina spinel castable, themain aggregate is tabular alumina, respectively in the castable matrix added magnesiapowder (200mesh with98fused magnesia) and different kinds of powder (1μ of α-Al2O3powder and95silicon powder)，after heating treatment in the low temperature(110℃),middle-temperature (1100℃), and high temperature(1600℃), the physical properties usingperformance and microstructure and phase composition has carried on the systematic studyof castable samples. the microstructure of the castable sample after treatment at differenttemperatures were studied by scanning electron microscope(SEM); the phase compositionof the castable sample after treatment at different temperatures were studied by X-raydiffraction (XRD).Add the right amount of magnesia powder and fine powders to the non-cementalumina spinel castables, at room temperature which could reduce apparent porosity of thecastable, promote densification of the castable, increasing the bulk density of the castable,thereby improving its structure at room temperature. The introduction of magnesia powderand micropowders also can affect the thermal shock resistance and slag resistanceperformance of the castable samples.The sample which add the magnesia sample after high temperature treatment, wichwith increasing porosity magnesia content increasing, the cold modulus of rupture and coldcrushing strength will reduce. When the magnesia content at4wt%, the thermal shockresistance of the sample is best.In corundum spinel castable added α-Al2O3powder and silica powder can effectivelyfill the gap of the castable, decreased the apparent porosity of the sample, while the bulkdensity of the sample will significantly increased. After heating treatment at110℃×24hand1600℃×3h, with the addition of the two powder increases, the volume density and thestrength are increasing, but the apparent porosity will decrease with the power increasing amount of powder; when the containing of α-Al2O3power more than6wt%, the apparentporosity and bulk density of the sample basically unchanged. Meanwhile, adding α-Al2O3power samples, at the high-temperature, α-Al2O3react with the magnesia of materials cangenerate spinel, make void defect of the castable decrease, make its intensity increase; Butwith the level of α-Al2O3power increase, the thermal shock resistance of the castablesample become worse and worse. When added silica powder in castable, which can play arole in promoting the sintering, make the sample more compact, the cold modulus ofrupture and cold crushing strength are improved; When the silica powder content is0.8wt%, the thermal shock number of samples reached the maximum, and the resistance toslag penetration index reaches the minimum, namely at this time the two optimalperformance; When the content of silica is1.0wt%, the resistance to slag erosion of sampleis optimal.