Determination Of Thermal Conductivity Of ESR Slag System Of 825 Superalloys

The thermal conductivity of slag is an important physical property parameter of slag.It is of great significance to know the thermal conductivity accurately for improving the metallurgical thermal efficiency and the accuracy of numerical simulation.With the rapid development of Chinese economy,energy gap is expanding year by year,energy efficiency is still low,and it becomes increasingly important to save energy and improve energy efficiency.In steel smelting,energy dissipation is mainly concentrated in the process of thermal conversion.Therefore,improving the efficiency of thermal conversion and reducing energy consumption is an important way to save energy,and the key to improve thermal efficiency is the accuracy of the value of thermal conductivity.On the other hand,the thermal conductivity of slag is an important parameter in the numerical simulation process,which directly affects the accuracy of the simulation results.Therefore,it is very important to study the thermal conductivity of slag.At present,the basic data of the measurement of thermal conductivity of metallurgical slag is still very lacking,and the existing data show that the values of thermal conductivity determined by different scholars differ greatly,which seriously affects the cognition of the heat transfer process of slag.The difference of experimental data not only comes from different temperature and slag system composition,but also is affected by experimental methods.Therefore,the application of transient hot-wire method in the field of metallurgy needs to further optimize and adjust the experimental conditions,so as to get more suitable for the application of thermal conductivity measurement method in the field of metallurgy.At present,the influence mechanism of slag system components and temperature on thermal conductivity is still unclear.It is necessary to further study and clarify the mechanism of thermal conductivity change,so as to better understand the thermal conductivity of slag system and improve the understanding of metallurgical heat transfer.In order to solve the above problems,the experimental conditions of the transient hot wire method and the influence of the experimental environment on the experimental results were first discussed,so as to optimize the experimental method.In this study,based on the optimized transient hot wire method,the input power of the experimental method was verified for the ternary slag system（40%CaO-20%Al₂O₃-40%Si O₂）,and the thermal conductivity of smelting Incoloy825superalloy slag system CaF₂-CaO-Al₂O₃-MgO-Ti O₂ was measured.The effects of the contents of CaF₂,MgO and Ti O₂ on the thermal conductivity of slag system at 1000℃～1500℃were studied.The influence of current intensity on the determination of thermal conductivity of slag system is analyzed,and the appropriate current intensity value is obtained.The influence of temperature and slag system composition on the thermal conductivity of slag system is discussed,and the relationship between the thermal conductivity of slag system and temperature is integrated.The action form and principle of temperature and slag system composition on the thermal conductivity are given by XRD phase analysis and thermodynamic theory.It is found that:（1）compared with concentric cylinder method,laser flash method and water-cooled tube method,the transient hot-wire method is more reasonable in measuring thermal conductivity of metallurgical slag system.（2）the current intensity should be in the range of 2.0 A when measuring the thermal conductivity of metallurgical slag system by transient hot-wire method.（3）when CaF₂-CaO-Al₂O₃-MgO-Ti O₂ slag system is in solid state at 1000℃～1200℃,the thermal conductivity of the slag system will increase with the increase of temperature,while at 1300℃～1500℃,the slag system is in liquid state,the thermal conductivity of slag system will decrease with the increase of temperature.（4）the thermal conductivity of CaF₂-CaO-Al₂O₃-MgO-Ti O₂ slag system increases with the increase of CaF₂ content,decreases linearly with the increase of MgO content,and decreases linearly with the increase of Ti O₂ content at the temperature of 1000℃～1500℃.