The chemical composition and fracture toughness of thermal barrier coatings (TBCs) before and after heat treatment were characterized, and the cracks around the interface between the coating and the substrate could be successfully eliminated and meanwhile the porosity of the coatings tended to reduce. The XRD analysis revealed the coatings were composed of non-transformable tetragonal t’ phase of ZrO ₂ and γ $\gamma $ -(Ni, Cr) with minor Ni3Al ( γ ′ $\gamma ^' $ ) precipitates. Additionally, the relationship between the heat treatment and wear resistance was systematically studied. The results indicated that both the hardness and fracture toughness increased after quenching process. The oxidation wear became more prominent after heat treatment, which probably resulted from the better bonding strength of coatings. Dense and homogeneous microstructure introduced by vacuum oil-quenching improved stabilization of the weight gain during thermal cycle test.

In-situ synthesis, microstructure, and mechanical properties of four TiB₂-Reinforced Fe-Cr-Mn-Al Steel Matrix Composites have been researched in this work. The microstructure and phases of the prepared specimens have been characterized by using scanning electron microscopy (SEM), X-ray diffraction technique, and transmission electron microscopy (TEM). The sintered specimens consisted of Fe₂AlCr, CrFeB-type boride, and TiB₂. The mechanical properties, such as hardness and compression strength at room temperature (RT) and at elevated temperatures (600 °C and 800 °C) have been evaluated. The compressive strength and Vickers hardness of the sintered specimens increase with the volume fraction of TiB₂ in the matrix, which are all much higher than those of the ex-situ TiB₂/Fe-15Cr-20Mn-8Al composites and the reported TiB₂/Fe-Cr composites with the same volume fraction of TiB₂. The highest Vickers hardness and compressive strength at room temperature are 1213 ± 35 HV and 3500 ± 20 MPa, respectively. As the testing temperature increases to 600 °C, or even 800 °C, these composites still show relatively high compressive strength. Precipitation strengthening of CrFeB and in-situ synthesis of TiB₂ as well as nanocrystalline microstructure produced by the combination of mechanical alloying (MA) and spark plasma sintering (SPS) can account for the high Vickers hardness and compressive strength.

With the rapid increase in electric vehicle (EV) ownership, the strategic planning and layout of charging infrastructure have become essential to encourage EV adoption. This study introduces a comprehensive multi-objective optimization method for selecting locations and designing layouts for high-power and extreme fast charging stations. By thoroughly accounting for user charging demands, economic expenses, and traffic conditions, a multi-objective optimization mathematical model is created aiming to minimize user time and costs while maximizing service capacity and user satisfaction. The model combines queuing theory, network topology analysis, and genetic algorithms to simultaneously handle discrete variables related to station placement, continuous variables for charging pile setup, and complex constraints. Using Panyu District in Guangzhou as a case study, a simulation model with 20,000 electric vehicles and 20 high-power and extreme fast charging stations is developed, focusing on the optimal arrangement of 120 kW, 240 kW, and 480 kW charging piles. The simulation results demonstrate that the optimized charging station layout scheme (13 units of 120 kW, 6 units of 240 kW, and 1 unit of 480 kW) lowers overall costs by 6.74%, reduces user charging waiting time from 1.54 h to 0.65 h, improves user satisfaction by 8.1%, and cuts the peak-to-valley difference in charging load from 900 kW to 450 kW. This work offers both theoretical insights and practical recommendations for the effective planning of electric vehicle charging infrastructure.