Tantalum (Ta) is a refractory metal with a body-centered cubic crystal structure. It exhibits outstanding physical and chemical properties, including a high melting point, high density, excellent ductility, superior corrosion resistance, and favorable biocompatibility. In recent years, it has been widely applied in the aerospace, chemical engineering, and medical device industries, and is a common sputtering target in the electronics industry. Ta targets are typically fabricated by plastic deformation followed by annealing of high-purity Ta ingots. A fine and uniform grain structure, together with a preferred crystallographic orientation, is critical for achieving high sputtering efficiency and improved film uniformity. However, due to inherent microstructural inhomogeneities in the initial ingot and nonuniform plastic deformation during processing, obtaining a refined and homogeneous microstructure—especially one with consistent crystallographic texture—remains a substantial challenge using conventional processing techniques. To address this issue, this study systematically investigates the influence of various rolling processes on the microstructure of high-purity Ta and proposes a novel processing strategy that integrates asymmetric rolling(AR) with subsequent recrystallization treatment.

High-purity Ta ingots are prepared by vacuum arc-melting in a Ti-gettered argon atmosphere. The ingots are processed by AR for a total thickness reduction of 90%, achieved by setting the speed ratio of the top and bottom rollers to 1.2∶1. To ensure homogeneous deformation, samples are rotated 135° in the normal direction and flipped between consecutive rolling passes. For comparison, synchronous rolling (SR) is also conducted under the same total reduction, with the upper and lower rolls operating at a speed ratio of 1∶1. The rolled specimens are then annealed at 1000 ℃, 1100 ℃, and 1200 ℃ for 1 h. Prior to all heat treatments, samples are sealed in vacuum quartz tubes to prevent oxidation. The microstructures and mechanical properties of the annealed specimens are characterized using electron backscatter diffraction, microhardness testing, and room-temperature tensile testing, respectively.

AR greatly enhances the equivalent strain by introducing additional shear deformation, thereby promoting more uniform deformation penetration through the sheet thickness and forming a distinct shear zone. This results in more pronounced grain fragmentation compared to SR. Furthermore, the AR sample exhibits a markedly lower maximum texture intensity(24.76 mud) than the SR sample (74.12 mud), along with a correspondingly reduced total texture fraction (54.2% vs. 74.8%). After annealing at 1200 ℃, both samples achieved nearly complete recrystallization. The average grain size of the AR sample (50.70 μm) is finer than that of the SR sample (64.90 μm). As the annealing temperature increases, the texture intensity decreases for both samples, with the AR samples consistently exhibiting lower texture intensity than the SR samples. Rolling induced notable hardening, increasing the microhardness to 201.9 HV in the AR sample and 196.3 HV in the SR sample. The yield strength of the AR sample reached 378 MPa, which is 63 MPa higher than that of the SR sample (315 MPa). Although the mechanical properties of both rolled specimens exhibited decreasing trends with increasing annealing temperature, the strength and hardness of the AR samples remained consistently higher than those of the SR samples.

AR is an effective technique for refining the grain size of Ta, weakening its texture, and enhancing its mechanical properties. This experiment involves the preparation, characterization, and application of pure Ta, thereby not only improving students' experimental design skills but also promoting their scientific thinking and innovative awareness.

Ultrahigh-temperature ceramics (UHTCs) are essential materials for aerospace thermal protection systems, including nose caps and wing leading edges, due to their excellent high-temperature mechanical properties, resistance to antioxidant ablation, and appropriate thermal expansion coefficients. However, their inherent brittleness results in low fracture toughness and poor thermal shock resistance, which limits their widespread use. Fabricating ceramic matrix composites through continuous fiber reinforcement and the precursor infiltration and pyrolysis method offers an effective solution, with ceramic precursors playing a key role in defining the final composite properties.

This study provides a comprehensive experiment on synthesizing and optimizing SiZrBC ceramic precursors, combining cutting-edge UHTC research with educational practices to address the high costs and low yields associated with traditional precursors. The experiment utilized a one-pot polymerization method with zirconium tetrachloride, tetraethyl orthosilicate (TEOS), boric acid, and boron phenol resin (BPR) as raw materials. It systematically examined the effects of precursor preparation temperature (80 ℃-120 ℃), Si source (TEOS), B source (boric acid), and C source (BPR), along with the influence of different pyrolysis atmospheres on the properties of the resulting ceramics. Characterization techniques included Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS).

The results showed that the best overall properties were achieved at a synthesis temperature of 80 ℃, with the addition sequence starting with the Si source, then the B source, followed by the C source. Pyrolysis was performed at 1550 ℃ in an argon atmosphere. This addition order significantly affected ceramic yield and microstructure. Specifically, initial addition of the Si source helped form a Si–O–Zr network, providing stable attachment sites for subsequent components, while early B source addition facilitated B–O bonds in the polymer backbone, acting as strong cross-linking points. The precursor was pyrolyzed at 1550 ℃ in an argon atmosphere to produce composite ceramic powder with optimal properties. After pyrolysis at 1000 ℃ in argon, the ceramic achieved a high yield of 64.7%, with fine grains averaging approximately 65.61 nm, and exhibited relatively low toxicity and low raw material costs. The pyrolysis atmosphere greatly influenced the final product: argon favored higher ceramic yields and finer grains by slowing gas diffusion and promoting network formation, while a vacuum atmosphere encouraged complete oxide reduction but accelerated boron loss via B₂O₃ evaporation and grain growth beyond 106 nm. Vacuum pyrolysis removed ZrO₂ impurities but resulted in lower ceramic yields and larger grains.

This experimental approach effectively integrates core materials science concepts with practical laboratory work, covering all stages from material synthesis and structural characterization to performance analysis. By systematically exploring processing-structure-property relationships, students develop a deeper understanding of ceramic precursor chemistry, pyrolysis mechanisms, and advanced characterization methods such as FTIR, XRD, SEM, and EDS. The use of low-toxicity, cost-effective raw materials ensures safety and accessibility in educational settings. This experiment improves the quality of materials chemistry education, enhances students’ practical skills in data analysis and problem-solving, and promotes innovative thinking vital for scientific research. Through project-based learning, students acquire critical research skills, recognize the importance of parameter optimization, and understand the connection between laboratory experiments and real-world aerospace applications, preparing them for careers in materials science and engineering.

Synthetic dye, a major contributor to global water pollution, poses substantial and irreversible threats to human health and ecological systems. Recently, water treatment technologies based on peroxymonosulfate (PMS) have emerged as a promising solution. The decomposition of PMS generates reactive oxygen species (ROS) with high redox potential, but the slow reaction rate limits its practical application in water remediation. To increase the PMS decomposition efficiency, a comprehensive experiment is designed to synthesize carbon-coated CeO₂–Co₃O₄ composite catalysts.

In this comprehensive experiment, a hollow CeO₂–Co₃O₄ precursor was initially prepared via the solvothermal method. Subsequently, a resorcinol–formaldehyde (RF) resin layer was applied to the precursor surfaces using the sol–gel process, followed by carbonization to form a core–shell structured material. Concurrently, by introducing silicon dioxide (SiO₂) interlayers of different thickness values as templates, two types of carbon-coated Co₃O₄–CeO₂ with a “rattle” structure were fabricated. The structural characteristics of the materials were analyzed using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and N₂ adsorption–desorption techniques. The performance of the catalysts was evaluated using methylene blue (MB) as a model organic pollutant, and scavengers were employed to identify the predominant ROS involved in the reaction.

The successful preparation of the designed materials was confirmed by TEM. Compared with the uncoated product (Co₃O₄–CeO₂), the RF and SiO₂ layers effectively inhibited grain growth during carbonization. The rattle-type composites exhibited significantly higher BET surface areas, particularly the one made with 0.75 mL tetraethyl orthosilicate or TEOS (Co₃O₄–CeO₂@h-C-1, 222.1 m²/g). In contrast, the BET surface area of the core–shell structured sample (Co₃O₄–CeO₂@C, 24.8 m²/g) was even lower than that of Co₃O₄–CeO₂ (55.8 m²/g) due to the sealing effect of dense carbon shell. The Co₃O₄–CeO₂@h-C-1 demonstrated the best catalytic performance with ¹O₂ and ${\text{SO}}_4^{·-}$ as the main ROS in MB degradation. This superiority is due to its highest BET surface area and unique rattle-type structure. Moreover, the small grain size of the metal oxides creates more defects and active sites on their surface, which is beneficial for PMS activation.

This comprehensive experiment simulates the entire scientific research process, encompassing the preparation, characterization, performance testing, and data analysis of carbon-coated Co₃O₄–CeO₂ composites with different structures. This experimental project trains students to understand the structure–activity relationship of catalysts and the comprehensive application of knowledge from chemistry and material disciplines, enhancing students' experimental design capabilities and fostering scientific thinking and innovative awareness.