Search

Basicity of titanium bearing blast furnace (BF) slag is critical for its crystallization behavior. Thermodynamics calculation indicates that rutile is the main phase after crystallization (or at room temperature). It precipitates during the cooling when the basicity of the slag is lower than 0.7. With increasing basicity, perovskite appears and becomes the main phase instead which contains titanium. Crystallization temperature of perovskite is higher than that of rutile and the other phases. Namely, perovskite crystallizes firstly from the molten slag during decreasing temperature. XRD analysis shows that CaTi21O38 is the main phase with a basicity of 0.6. CaMg0.39Al0.87Ti0.48Si1.26O6, CaTiSiO5 and CaMgSi2O6 are the main crystallization phases with a basicity of 0.8. The difference between experimental and thermodynamics calculation is due to the complicate crystallization behavior of the multiple slag under super cooling rate. When the slag basicity increases to 1.1, the main precipitatied phase is perovskite, which agrees well with theory calculation. In addition, the crystal structure of the synthesized titanium bearing slag is basically similar regardless of the basicity.

The surface tension of liquid Ti-Al alloys at 1758 K was determined by an improved sessile drop method. The surface tension of liquid Ti-Al alloys was calculated using the Butler's model and several modified ideal solution models. Results show that the surface tension of liquid Ti-Al alloy decreases with increased Al concentration. Experimental results agree well with both the Butler's model and the modified ideal solution model. The segregation of Al atoms to the surface occurs at all bulk concentrations of Ti-Al alloys. Al with lower surface tension prefers to segregate on the surface of liquid Ti-Al alloy, whereas Ti with higher surface tension prefers to segregate inside the molten alloy. The effect of surface active solute on the surface tension of liquid Ti-Al alloy was also discussed. Sulfur is found to have a larger effect on the surface tension of alloy. The surface tension of liquid Ti-Al alloy decreases with increased sulfur concentration. Sulfur concentration on the surface is higher than that in the bulk. Thus, the adsorption of sulfur for Ti-Al alloys is a positive adsorption.

As a new structural and functional material, metal foam has been proven to obtain excellent properties when compared with dense ones. In the present paper, the powder metallurgy with a space holder technique was used to prepare magnesium foam. The porosity of the foam ranges from 38.90% to 57.50%, when the elastic modulus decreases from 8.50 GPa to 3.30 GPa, and the initial yield stress decreases from 24.90 MPa to 9.40 MPa. The magnesium foam has lower yield stress and longer stress platform, so it can be used as good cushioning energy absorbing materials.

Thermal management system is crucial for hypersonic vehicles, in which a large amount of thermal energy due to aerodynamic heating needs to be removed by hydrocarbon fuel. In this study, an experimental investigation is performed on the convection heat transfer of supercritical hydrocarbon fuel in a long mini tube. The horizontal test tube has an inner diameter of 1.0 mm and a length-to-diameter ratio of 980, which are close to those of practical heat-transfer channels in the thermal management system for hypersonic vehicles. The non-linear distribution characteristics of wall temperature and heat transfer coefficient along the test tube are presented. The heat transfer regions of hydrocarbon fuel are classified into initial heat transfer (IHT), normal heat transfer (NHT), enhanced heat transfer (EHT) and deteriorated heat transfer (DHT). The heat transfer mechanisms in each heat transfer region are discussed in detail. The heat transfer of hydrocarbon fuel are affected by the dramatic variations in thermo-physical properties and buoyancy effect. Heat transfer is commonly deteriorated under disadvantageous thermo-physical properties and absence of buoyancy effect. The results could be beneficial for the analysis and design of the thermal management system for hypersonic vehicles.

Low current efficiency of the FFC Cambridge process made it no obvious advantages in cost compared with the traditional process to produce metals. Effect of the changed electrolysis cell on the current efficiency has been studied. Put the cathode into an alumina tube with a hole can efficiently avoid short circuit and the cathode contaminated by carbon produced from graphite anode. The results show that the current efficiency can be improved greatly by reducing the electric field intensity in the electrolysis cell. The high background current is mainly caused by the electronic conductivity in the electrolysis cell. Otherwise, pollution of the cathode is avoided, the depletion of the anode sharply decreases and the deoxidation of the samples greatly improve when using the improvement electrolysis cell.