Physical and technological properties and the operational reliability of quartz nozzles (downtubes) used for continuous casting

Abstract

process are recommended for service under the conditions of high mechanical loads and erosion (including the temperatures in the 1700-1750~ range). CONCLUSIONSAt high temperatures, periclase-carbon systems exhfbit a significant change in their phase composition and spatial distribution of the oxide and the carbonaceous components. The structure evolution of the periclase-carbon refractories occurs due to sintering of the mineralogical filler under the conditions involving a change in the volumetric proportions of the oxide and the carbonaceous phases because of the oxidation-reduction reactions.The refractories made from fused quartz are widely used in metallurgical units under severe service conditions [i, 2].Steel casting (pouring) nozzles (downtubes) based on quartz glass are used for the vertical, horizontal, and curvilinear types of casting units. The specific service conditions (performance) of the immersed quartz nozzles used for casting low-alloy and mild steels in the curvilinear type units were previously examined [3][4][5][6][7][8].Quartz nozzles are recommended [9] for casting the steels containing less than 1%* Mn. However, the long-term service of the nozzles at the Novolipetsk Steel Plant indicates the possibility of using them for casting the steels containing up to 1.5% Mn. In this case, the life # (stability) of quartz nozzles is considerably reduced.When the chemical composition of the nozzle material is in the ranges 98.3-99.9% Si02, 0.02-1.5% AI20~, 0.01-0.25% R20, 0.01-0.15% Fe203, it does not have a significant effect on the life if the cristobalite content in the fired products is restricted up to 1.5-5% [7,8, 10]. *Here and elsewhere, weight contents are given. #The life (stability) is characterized by the quantity of metal poured through a nozzle up to its complete wear (destruction).