Thermal simulation equipment (TSE) was recently developed to simulate the solidification process in the industrial continuous casting of slab. The grain growth, solid-liquid interface movement, and columnar-to-equiaxed transition (CET) in the continuous casting process can be reproduced using this equipment. The current study is focused on the effects of different cooling rates and superheat conditions on the grain growth in the solidification process of chromium-saving ferritic stainless steel (B425). The temperature distribution and microstructure evolution are simulated by a Cellular Automaton-Finite Element (CAFE) model. The experimental results demonstrate that the temperature gradient and the grain growth rate of the sample can be effectively controlled by the equipment. It is observed from optical micrographs of the microstructure that the average equiaxed grain ratio increases when the superheat temperature decreases. The average equiaxed grain ratio is approximately 26% and 42% under superheat conditions of 40 °C and 30 °C, respectively, and no apparent columnar grain generation in the samples occurs under superheat conditions of 10 °C and 20 °C, as the result of a large thermal resistance at the copper-sample interface and low superheat inside the sample. A lower cooling rate results in a higher equiaxed crystal ratio in the sample. As the cooling rate decreases, the equiaxed crystal ratio becomes 14%, 23%, and 42%. Comparing the simulation results with the experimental observations, a reasonable qualitative agreement is achieved for the chilled layer thickness, grain morphology, and CET in the sample. Thus, the CAFE model in the current study can accurately predict the grain growth under different superheating and cooling rate conditions.

To overcome the low lithium ion diffusion and slow electron transfer, a hollow micro sphere LiFePO₄/C cathode material with a porous interior structure was synthesized via a solvothermal method by using ethylene glycol (EG) as the solvent medium and cetyltrimethylammonium bromide (CTAB) as the surfactant. In this strategy, the EG solvent inhibits the growth of the crystals and the CTAB surfactant boots the self-assembly of the primary nanoparticles to form hollow spheres. The resultant carbon-coat LiFePO₄/C hollow micro-spheres have a ~300 nm thick shell/wall consisting of aggregated nanoparticles and a porous interior. When used as materials for lithium-ion batteries, the hollow micro spherical LiFePO₄/C composite exhibits superior discharge capacity (163 mAh g⁻¹ at 0.1 C), good high-rate discharge capacity (118 mAh g⁻¹ at 10 C), and fine cycling stability (99.2% after 200 cycles at 0.1 C). The good electrochemical performances are attributed to a high rate of ionic/electronic conduction and the high structural stability arising from the nanosized primary particles and the micro-sized hollow spherical structure.

Slag entrapment is a critical problem that affects the quality of steel. In this work, a three-dimensional model is established to simulate the slag entrapment phenomenon, mainly focusing on the slag entrapment phenomenon at the interface between slag and steel in molds with different widths. The large eddy simulation (LES) model and discrete particle model (DPM) are used to simulate the movements of bubbles. The interactions between phases involve two-way coupling. The accuracy of our mathematical model is validated by comparing slag–metal interface fluctuations with practical measurements. The results reveal that the average interface velocity and transverse velocity decrease as the mold width increases, however, they cannot represent the severity of slag entrapment at the interface between slag and steel. Due to the influence of bubble motion behavior, the maximum interface velocity increases with mold width and causes slag entrapment readily, which can reflect the severity of slag entrapment. On this basis, by monitoring the change of impact depths in different molds, a new dimensionless number “C” is found to reveal the severity of slag entrapment at the interface between slag and steel. The results show that the criterion number C increases with mold width, which is consistent with the results of flaw detection. Therefore, criterion number C can be used to reflect the severity of slag entrapment in different molds.