In-situ engineered ZrB2-ZrSi2-MoSi2 coatings with self-healing multiphase glass networks for superior oxidation protection at 1973 K

Recently, a research team led by Teacher Ren Xuanru, in collaboration with China University of Mining and Technology, National University of Science and Technology MISIS (Russia), and other institutions, has achieved new progress in the field of ultra-high temperature ceramic coatings. The related findings have been published in the CAS Q1 Top journal Corrosion Science (Impact Factor=8.5), under the title "In-situ engineered ZrB₂-ZrSi₂-MoSi₂ coatings with self-healing multiphase glass networks for superior oxidation protection at 1973 K". Chen Yuexing is the first author of the paper, while Researcher Ren Xuanru and Associate Researcher Ji Xiang are the corresponding authors.

Aiming to address the challenge of protective failure in ZrB₂-based coatings caused by structural loosening during oxidation, this study proposes a dual-silicide synergistically enhanced in-situ alloying strategy based on one-step powder source synthesis. This approach successfully prepared ZrB₂-ZrSi₂-MoSi₂ composite powders with precisely controllable composition, which were then used to construct high-performance anti-oxidation coatings on a graphite substrate. The optimized ZZM40 coating (with 40 vol.% MoSi₂) demonstrated a reduction in oxygen permeability and carbon loss rate by 98.21% and 84.03%, respectively, compared to the undoped coating at 1973 K, achieving a protective efficiency of 99.58%. This performance enhancement stems from the in-situ formed glass phase during oxidation, which exhibits both high fluidity and self-healing characteristics. Concurrently, the in-situ precipitated nano-scale MoB phase effectively suppresses the volatilization of B₂O₃ through a pinning effect, thereby achieving a synergistic improvement in thermal stability and oxygen barrier performance. It is noteworthy that when the MoSi₂ doping content is excessively high (50 vol.%), excessive volatilization of MoO3 leads to a decrease in the viscosity of the glass phase and triggers chain-like expansion of defects, consequently increasing the carbon loss rate of the coating by 34.43% compared to ZZM40. The in-situ alloying strategy of the powder source proposed in this study validates the defect repair mechanism enhanced by dual silicides for oxygen barrier, providing an important theoretical basis for the design and application of next-generation high-temperature thermal protection materials.