Interaction Between Liquid Steel and AlN Substrate Containing Al-Y-Oxides
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INTRODUCTION
NITRIDE ceramics have significant potential for use in steelmaking industries owing to their high-temperature thermal performance and mechanical properties. Currently, the properties of nitride ceramics in steelmaking are being studied and improved.[1–3] Nitride ceramics, especially aluminum nitride (AlN), have been widely investigated. The solubility of AlN in liquid iron at 1873 K (1600 °C) is less than silicon nitride or boron nitride, as listed in Table I.[4] The calculated thermal conductivity of AlN is 320 W/m K at the room temperature,[5] and the coefficient of thermal expansion (CTE) ranges from 4 to 4.5 9 106 K1[6] Therefore, AlN has good thermal shock resistance owing to its high thermal conductivity and low CTE. Moreover, Watari[5] reported AlN materials containing a lower oxygen content with higher thermal conductivity. The influence of nitride ceramics on the wettability of molten steel is of great importance, as molten steel can directly come into contact with ceramic components such as the nozzle and the sliding plate. Labbe et al.[1]
YAN LUO, MING LI, PIOTR R. SCHELLER, and LIFENG ZHANG are with the School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China. Contact e-mail: [email protected] SEETHARAMAN SRIDHAR is with the Department for Metallurgical and Materials Engineering, Colorado School of Mines, Golden, CO 80401. Manuscript submitted October 8, 2017.
METALLURGICAL AND MATERIALS TRANSACTIONS B
and Amadeh et al.[4,7] measured contact angle and revealed the presence of a reaction layer at the interface between steel and pure AlN-based materials. Xuan et al.[3] reported that titanium nitride (TiN) had a good corrosion resistance in molten steel. Furthermore, an interface layer was observed at the interface between the molten steel and the TiN substrate. Several papers have reported the reaction layer at the interface between AlN and steel, as presented in Table II. Owing to the difficulty in the preparation of pure AlN substrates with small surface roughness and low porosity, yttrium oxide (Y2O3) is frequently used as a sintering aid. Taranets et al.[8] investigated the effects of porosity (about 27 pct without Y2O3 vs approximately 0 pct with Y2O3) and roughness on wettability and the interaction of the AlN substrate with brazing alloys. Koltsov et al.,[9] Prin et al.[10] and Ho et al.[11] also studied the wetting of alloys on an AlN substrate containing Y2O3 as a binder. Moreover, the effect of the interfacial reaction on the wettability between AlN substrate and many metallic materials was also investigated. However, the specific details of the reaction product and the path during the reaction between liquid steel and AlN substrate containing Y2O3 have rarely been investigated. Therefore, the objective of the current work was to investigate the reaction between liquid steel and two types of AlN substrates and to investigate the wetting behavior using a sessile drop furnace. The reaction products of nitride and oxide we
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