Metallurgical and Materials Transactions B最新文献

Ti is produced by the Kroll method, mainly by carbothermic chlorination, magnesiothermic reduction, and vacuum distillation, which result in complex processes, low efficiency, and high cost. Although Ti has many excellent properties, its high production costs limit its widespread applications. There is an urgent need to develop new Ti extraction processes to reduce the cost of Ti production. In this study, we propose a new method for the direct preparation of low-oxygen Ti powder from TiO₂ using Mg as a reducing agent and the formation of CeOCl (2Mg (l) + TiO₂ (s) + 2CeCl₃ (l) = Ti (s) + 2CeOCl (s) + 2MgCl₂ (l)). First, a deoxidization experiment of Ti with Mg as a deoxidizer was conducted, and the ability of Mg to deoxidize Ti was demonstrated. At 1273 K, when the activity of CeCl₃ was 1, the oxygen concentrations of Ti-A and Ti-B were 380 and 270 ppm, respectively. Subsequently, the TiO₂ reduction experiment was conducted using Mg as the reducing agent. The results showed that MgO activity was effectively reduced by the formation of CeOCl (MgO(s) + CeCl₃(l) = MgCl₂(l) + CeOCl(s)). When the system reached the Mg/MgCl₂/CeOCl/CeCl₃ equilibrium, low-oxygen Ti powder below 1000 ppm was directly produced from TiO₂.

The research focused on the effect of graphite proportion and the incorporation of fly ash in Fe-Cu-based friction materials produced via powder metallurgy technique. Microstructural investigation of the specimens demonstrated the homogenous distribution of the secondary element (Cu), lubricant (graphite), and reinforcements (fly ash) in the matrix (Fe). A maximum density of 5.7 g/cm³ was attained for the specimens, with an overall density of 70 pct of theoretical density. FM03 specimens showed a better wear resistance of 4.7 × 10⁻⁸ g/Nm with an optimum coefficient of friction of 0.4. The specific wear rate of the conventional friction material was 97.7 pct higher than the FM03 specimens.

Graphical Abstract

The melting and motion of ferroalloys play a crucial role in the mass transfer and homogenization of molten steel in ladles. Heat transfer, melting, and solidification behavior of an alloy affect its size, thereby altering its motion within the gas-stirring ladle. This study established a heat transfer and solidification-melting model for alloy particles in high-temperature metal liquids. The computational fluid dynamics (CFD) method was used to simulate the fluid within the ladle, and the discrete element method (DEM) was employed for the alloy particles. This coupling approach elucidates the motion trajectories of different types of alloys in molten steel under flow and heat exchange, particle heating, melting, and shrinkage conditions. Furthermore, the effects of alloy size, initial alloy temperature, molten steel flow rate, and molten steel temperature on the melting behavior of different types of alloys were investigated. The results showed that the melting time exponentially increased with increasing alloy size or decreasing molten steel flow rate. Moreover, the alloy melting time decreased with increasing initial alloy temperature or molten steel temperature. The impact of these factors on the melting of FeCr, FeMn, FeSi, and Al alloys was also evaluated. Furthermore, FeSi and Al alloys added at different positions in the ladle with symmetric dual gas bottom blowing had a residence time of only 1 second in the molten steel and did not completely melt. These findings indicate that FeSi, Al, and FeCr alloys should be added at the 0.4R position in the symmetrical plane. Furthermore, the − 0.4R or − 0.2R positions are more favorable for the melting of FeMn.