Investigation of wetting characteristics of liquid iron on dense MgAION-based ceramics by X-ray sessile drop technique
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I. INTRODUCTION
IN the modern steel industry, the reactions between refractories and molten iron are receiving great attention due to the refractories’ contamination resulting in nonmetallic inclusions.[1,2] These necessitate the development of new-generation refractories that can survive in extreme conditions—not only high temperatures and high heat fluxes, but also wear, chemical attack, and mechanical loads.[3] Such a development in turn requires a fundamental understanding of the reactions between the materials and molten iron. The present work is thus motivated. In recent years, magnesium aluminate spinel (MgAlON), a solid solution of Al2O3, MgO, and AlN, has attracted considerable attention for its wide applications in hostile environments, such as high-temperature-window materials and high-performance refractories, because of its favorable combination of mechanical (hardness) and optical properties.[4–9] A number of publications have appeared about the application of MgAlON as refractories. The results show that adding some MgAlON to carbon-bonded refractories can improve their resistance to slag and steel corrosion.[10–13] Boron nitride (BN) demonstrates excellent thermal shock resistance and machinability, in addition to its nonreactive nature.[14] In addition, their composites, MgAlON-BN, have been verified to have excellent mechanical and chemical properties Z.T. ZHANG, Graduate Student, T. MATSUSHITA, Doctor, and S. SEETHARAMAN, Professor, are with the Department of Materials Science and Engineering, Royal Institute of Technology, SE-100 44 Stockholm, Sweden. Contact e-mail: [email protected] W.C. LI, Professor, is with the Department of Physical Chemistry, University of Science and Technology of Beijing, Beijing, People’s Republic of China. Manuscript submitted October 22, 2005. METALLURGICAL AND MATERIALS TRANSACTIONS B
as well as thermal shock durability.[15–17] Thus it is expected that this composite could find applications as high-performance refractories that can be used, for example, in special refractory nozzles, tubes, and break rings for the continuous casting of steel. To our knowledge, no systematic study of the contact angle between MgAlON-BN composites and molten iron under different oxygen partial pressures has been carried out so far. The present paper presents the results of wetting characteristics of liquid iron on MgAlON-based ceramics under different oxygen partial pressures at a given temperature. SEM, XRD techniques were used to examine the interfacial parts. II. EXPERIMENTAL PROCEDURE The X-ray sessile drop technique was used. The oxygen partial pressures were controlled by using different ratios of CO, CO2, and Ar gases. The contact angles were measured as a function of time at a given PO2. A. Materials Pure iron rod with a 5-mm diameter supplied by Goodfellow Cambidge Ltd. was used. Table I presents the impurities of iron samples. The amount of oxygen was below analysis level. Sulfur and silicon concentrations were 3.4 and 16 ppm. Pure MgAlON and MgAlON-BN composites were synthesiz
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