Study On Interfacial Phenomenon Among Steel-Slag-Lining Refractory System

The current study focuses on the interfacial phenomenon in metallurgy industry. The wettability between slag and refractory in two systems and the wettability between steel and oxide in another two systems were studied.The magnesia in MgO-C refractory could be easily wetted by the slag. The addition of graphite was the main reason for the non-wettability between slag and substrate. The contact angle between the slag and MgO-C substrate was 130° at 1370?. Above 1470 ?, the reaction between MgO and C occurred and lead to a porous substrate due to the evaporation of reaction product. Both the consumption of carbon and the formation of pores resulted in the increase of wettability and the penetration of slag. In this system, the reaction in the substrate was the main influence factor that affected the wettability between slag and MgO-C substrate.The wettability between dolomitic refractory and slag with basicity varied from 2.5 to 1.25 showed a different trend. However, the final contact angle was nearly the same, i.e.5°. Slag with lower basicity wet the substrate faster at a lower temperature, while slag with higher basicity wet the substrate slowly at a higher temperature. The MgO and CaO in the substrate existed separately. MgO grain was stable contacting with all slags. The CaO could dissolve into the slag or react with the slag, which caused the increase of wettability and penetration. Slag with lower basicity absorbed CaO more easily. Therefore, the slag penetrated deeper. When the CaO in the substrate reacted with slag, a Ca₃SiO₅ layer generated in the interface, preventing the further penetration of slag. In this system, the reaction between the refractory substrate and slag was the main influence factor that affected the wettability between slag and dolomitic substrate.There was no reaction between pure iron and tundish lining refractory, but the structure of substrate changed at high temperature. The MgO grain in the substrate gathered and grew up, the other oxides formed a continuous low melting phase, both of them lead to the increase of surface roughness, and finally affected the wettability to some extent. The contact angle was larger for the pure iron on a rougher substrate. But the influence law was not so obvious. Overall, the contact angle between pure iron and tundish lining refractory was 113° at 1550? and 108° at 1626?. The pure iron didn't wet the substrate, there should be no penetration. However, the pure iron could penetrate into the substrate where the low melting phase existed. In this system, the change of the substrate structure could affect the wettability a little bit. On the whole, it was a stable system.Pure iron didn't react with spinel substrate, but in some conditions, the pure iron might react with spinel substrate indirectly. Therefore, the wettability was changed. The contact angle between the general pure iron A and substrates containing different MgO and Al₂O₃ decreased first and then increased with the increase of Al₂O₃ content. The measured contact angles ?Fe-MgO:133°, Fe-MgO·Al₂O₃:113.4°, Fe-Al₂O₃:126.9°? were close to the values in literature. And other contact angles were also in consistent with Cassie's equation. By the way, the temperature had little influence on the contact angle. On the other hand, pure iron B contained high Al content. The contact angles between pure iron B and various substrates were larger than the previous results at the same conditions. The contact angle increased with the increase of Al₂O₃ content in the substrate. MgO in the substrate was reduced by H2. Then, the reaction product, Mg vapor, dissolved into pure iroa The thermodynamic equilibrium of the pure iron indicated the formation of MgO-Al₂O₃ and CaO-Al₂O₃ layer on the surface of the metal drop. In this system, the high Al content in the pure iron and the indirect reaction between pure iron and substrate was the main influence factor that affected the wettability between liquid iron and spinel substrate.