Use of Borom and Lithium Oxides as a Replacement of Fluoride Compounds in Mold Powders
Journal Title: Scholars Academic Journal of Biosciences - Year 2015, Vol 3, Issue 3
Abstract
Abstract: The demands on the care of the environment, has impulsed the researchers to develop new mold powders without fluor content in their composition. Nevertheless, the new products need cover the important process requirements and avoid metallurgical problems. The main reason of the substitution of fluoride compounds is associated with emissions of fluorinated gases that cause health problems in operators. Also, provoke environment contamination and cooling water that could cause serious damage or corrosion on the equipment in the industrial plants. In the steel continuous casting process, the presence of a lubricant layer between the oscillating mold and the steel shell formed (during the first stage of solidification) is essential to ensure the good quality of the product. This layer should permit the transfer of heat from the liquid steel to the cooling water in the mold and ensure good physical properties in order to achieve the required lubrication. The use of mold powder, which forms a liquid slag film in the space between the steel shell and the mold, is now standard practice in the continuous casting process. That is why the design of these products acquires a significant importance. This paper presents a comparative characterization of a commercial mold powder and a synthetic slag without fluor compounds, designed in the laboratory. The oxides used in order to replace fluorine are B2O3 and Li2O. The results include physical properties such as viscosity at different process temperatures. These values obtained, by theoretical calculus using Riboud model, were compared with results estimated applying the software Fact Sage. In order to predict heat transfer behavior of both slags, the crystallization tendency was studied by experimental tests. The crystalline and glassy phases identification, were carried out by light and scanning electron microscopy (SEM/EDS) and checked by X ray diffraction (XRD). A thermodynamic simulation of the systems using Fact Sage corroborated the information obtained. Keywords: mold powders, viscosity, crystallization tendency, environment, continuous casting
Authors and Affiliations
M. A. Valentini, E. Brandaleze
Keywords
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