With the advancement of hypersonic vehicles, extreme high temperature environments have imposed increasingly stringent requirements on the performance of thermal protection systems. Consequently, the development of high-performance thermal protection materials capable of withstanding extreme conditions has become a primary focus of current research. Ultra-high temperature ceramics (UHTCs) and their composites, known for their excellent oxidation resistance and ablation performance, are regarded as highly promising non-ablative thermal protection materials. This paper provides a systematic review of recent research progress on UHTC composites in several key areas, including innovations and optimizations in fabrication processes, exploration of toughening strategies and mechanisms, in-depth studies on oxidation and ablation resistance mechanisms, and the development and potential applications of high-entropy ceramics. Furthermore, the paper discusses the practical application prospects of UHTCs and their composites in extreme environments, analyzes the current technical challenges, and proposes future research directions and priorities.

Thermal and environmental barrier coatings play a crucial role in protecting high-temperature structural components in gas turbine engines. As turbine inlet temperatures continue to rise, corrosion challenges posed by dust, volcanic ash, and other particulate matter—collectively known as CMAS—have become increasingly severe. Understanding the reaction mechanisms between CMAS and these coatings, identifying the key factors influencing CMAS corrosion, and developing methods to inhibit CMAS infiltration are essential for advancing high-performance gas turbine engines. This review examines the origins of CMAS corrosion and summarizes recent research on CMAS corrosion mechanisms in thermal and environmental barrier coating materials. Additionally, the role of rare earth elements in CMAS corrosion and various strategies to mitigate CMAS effects are discussed. Finally, the review highlights potential directions for future research.

It is of great significance to search oxide thermal/environmental barrier coatings (T/EBCs) with high working temperatures and thermal expansion coefficients (TECs) matching to different substrates. ABO₄-type oxides have been widely studied due to their high working temperatures, adjustable TECs, and low thermal conductivity. In this work, ABO₄-type (A=Ga, In, Cr; B=Nb, Ta) oxides are studied as EBC candidates based on their relatively low TECs. The influences of crystal structures, distortion degree, types of polyhedrons, as well as the A- and B-site ionic radii and atomic weights on TECs are discussed. It is found out that the TECs of ABO₄-type oxides are not depended on one single factor, and reducing A-site ionic radius may be a good way to decrease their TECs. Based on the TECs, AlNbO₄, InNbO₄, and GaTaO₄ are chosen as EBCs for C-, SiC-, and Al₂O₃-based substrates, respectively. The similar TECs between ABO₄-type oxide EBCs and substrates are beneficial for reducing interfacial thermal stress, which is good for their long-term applications. This work shows that the applications of ABO₄-type oxides can be expanded by effectively regulating TECs.

In order to get a comprehensive understanding of the corrosion behaviour of mild steel (110) with alanine, arginine, cysteine, and tyrosine in gas and aqueous phases, a systematic theoretical study using MC simulation was conducted in the current investigation. Stronger interfacial spontaneous adsorption of amino acid molecules across the Fe (110) surface in the investigated environment is made possible by the more negative adsorption energy values found in the MC simulation. Effectively repelling the corrosive particles from the substrate and delaying their aggregation are the capabilities of four amino acids. The results of the MC simulation also show that, in order to stop corrosion, amino acid molecules replace any other ions or solvent water that had previously been adsorbed on the metal surface. The trend of tyrosine > cysteine > alanine > arginine is shown by the protection capacity derived from the MC simulation. Furthermore, the DFT studies demonstrate that, charge transfer takes place within the molecule based on the calculated E-HOMO and E-LUMO energies. When adsorbed onto a metal surface, heteroatoms like nitrogen, oxygen, and sulphur in an amino acid structure provide the stronger inhibition. The decreased HOMO-LUMO gap, indicating improved electronic contact with the Fe (1 1 0) surface. A greater reactivity and potential for electron transfer are suggested by the EHOMO and ELUMO values (EHOMO −19.71 eV for alanine, −16.83 for cysteine, −10.73 for arginine and −16.80 for tyrosine) and (ELUMO EHOMO −10.81 eV for alanine, -−9.34 for cysteine, −2.69 for arginine and −9.06 for tyrosine) which are advantageous for adsorption onto the Fe (1 1 0) surface. Current study finds that, alanine, arginine, cysteine and tyrosine were emerging as a novel and effective and sustainable corrosion resistance agent for acid pickling and cleaning procedures. These outcomes may lead to the development of more and large-scale green inhibitors and a better understanding of their mechanisms for eco-friendly industrial processes.

Flexible piezoelectric composite (FPC) materials with strong designability are increasingly utilized in vibration control and structural health monitoring. The sensing and actuating performances of FPCs are directly affected by the several parameters, such as ceramic fiber volume fraction, flexible interdigitated electrode width, electrode spacing, and component thicknesses. These parameters should be optimized in order to make the tradeoff between the sensing-actuation performance and the compliance. This study systematically explored the relationships between material properties (such as electrostrain coefficients, dielectric coupling coefficients, and compliance matrix) and component parameters. A representative volume element (RVE) model at the microscale was employed to investigate the electric field distribution and sensing/actuation effects of FPCs with varying parameter configurations under voltage excitation. This analysis identified optimal component parameter ratios for FPCs, providing a theoretical foundation for their design and fabrication. The study concluded that an FPC with a ceramic fiber volume fraction of 75%, electrode spacing of 0.1 mm, and electrode width of 0.01 mm achieves optimal sensing and actuation performance while maintaining good compliance. This research offers valuable insights for the development of flexible piezoelectric composites with tailored properties for advanced applications.