Papers by Keyword: Slag Resistance

Abstract: The technology for manufacturing corundum-carbide-silicon refractories with increased slag resistance has been developed. It is shown that one of the directions for improving the quality of carbon-containing products is the creation of protective antioxidant coating on the surface of particles. A dense protective film is formed during the processing on the surface of carbon-containing particles. The coating does not break down when heated to the melting temperature of steel. Therefore, the number of heat-conducting particles in the bond can be increased without the risk of loss of strength. An increase of the number of high-heat-conducting particles reduces the value of the temperature gradient inside the refractory and reduces the zone impregnated with the melt. A technique has been developed that makes it possible to determine the degree of interaction of a refractory with metal (slag) in ground samples under the binocular microscope MBS-9. The proof of high slag resistance is the depth of penetration of metal and slag into the structure of the sample by not more than 1 to 2 mm without changing the lateral surface of the conical hole.

Abstract: The MgAl₂O₄ spinel ceramic specimens with five different alumina contents ( w(Al₂O₃)=66%,72%,78%,85%,90%) were prepared using alumina micropowder and magnesia micropowder as raw materials, after mixing, shaping, drying, and heating at 1800 °C. The crucible specimens were tested for slag corrosion with commercial gasifier slag at 1500 °C for 2 h under oxidazing and reducing atmosphere. The specimens before and after slag test were studied by analyzing the microstructure and element distributions of corroded specimens with XRD, SEM and EDS. The results show that the slow dissolution of spinel into slag was observed because a low melting point material was formed by spinel reacting with CaO and SiO₂ in slag on the surface of the spinel block. Meanwhile, FeO_x in the slag was absorbed around the surface of spinel block to form the multiple solid solution, which was composed of MgO-Al₂O₃-FeO_x and had a denser microstructure. The absorption of FeO_x in slag had contributed to the resistance to slag penetration for the spinel. The relationship between the absorption capacity of spinel on FeO_x and the chemical composition of spinel was discussed.

Abstract: The effect of phase composition and microstructure of Al₄SiC₄-Al₄O₄C composite refractories after sintered and immersion in the slag on its slag resistance was preliminary investigated. The penetration layer in refractories synthesized at 1700 °C resulted from loose microstructure led to worse slag resistance. While the refractories synthesized at 1800 °C presented better slag resistance because the dense microstructure and higher Al₄SiC₄ content inhibited the slag penetration and corrosion.

Abstract: The effects of varying the additions of magnesium aluminate spinel (0, 3, 6, 9, 12 wt. %) on the physical properties and slag resistance of Al2O3-SiC-C based castables were investigated. The composition of the specimens was determined by X-Ray diffraction (XRD). The results revealed that the incorporation of appropriate amount of MgAl2O4 in Al2O3-SiC-C based castables could promote the sintering of the specimens, decrease apparent porosity, and improve bulk density and strength. The slag resistance of the castables was improved due to an increase in the viscosity of molten slag, caused by the solid solution of Fe2+ or Fe3+ ions from the molten slag in MgAl2O4. However, further addition would led to a decrease in slag resistance because much Mg2SiO4 was produced.

Abstract: The effects of SiC addition on physical properties and slag resistance of MgO-based castables were investigated using magnesia as the main raw and silica micropowder as binder. The result revealed that with increasing SiC addition, dried strength decreased, medium and high temperature strength first increased and then decreased and reached a maximum at 3% SiC addition. The hot modulus of rupture (HMOR) of the materials maximized at 3% SiC addition. The slag penetration resistance of the castables was improved while resistance to slag attack was deteriorated with the increase in SiC addition. The materials exhibited optimum slag resistance at 3% SiC additions.

Abstract: This paper studied the impact of different additives and their amount on the performances of unfired magnesia-calcia brick by detecting cold crushing strength, volume concentration, after-firing linear change, slag resistance and microstructure. The results showed that samples with Zirconia or Zircon had relatively high cold crushing strength. The sample with 4% TiO₂ had the maximum volume concentration after firing. With the increase in the amount of additives, contraction occurred to all the samples, in which samples with Zircon had the smallest linear change and the most stable volume. Samples with 4% ZrO₂ and Zircon had better slag resistance.