In-situ engineered ZrB2-ZrSi2-MoSi2 coatings with self-healing multiphase glass networks for superior oxidation protection at 1973 K
Yuexing Chen, J. Paul Chen, Xiang Ji, Peipei Wang, Zhichao Shang, Chengshan Ji, Ph. V. Kiryukhantsev–Korneev, Е. А. Левашов, Xuanru Ren, Xueqin Kang, Baojing Zhang, Ping Zhang, Xiaohong Wang, Peizhong Feng, Junfei Peng, Junfeng Wang, Kun Song
Abstract
To address the protection failure of ZrB 2 -based coatings caused by structural loosening during oxidation, an in-situ alloying strategy with dual-silicide synergistic enhancement via one-step powder-source alloying is presented in this study. The approach successfully produced ZrB 2 -ZrSi 2 -MoSi 2 composite powders with precisely controllable composition, which were subsequently used to construct high-performance oxidation resistant coatings on graphite substrates. The optimized ZZM40 coating with 40 vol% MoSi 2 demonstrated a remarkable 98.21 % reduction in oxygen permeability and an 84.03 % reduction in carbon loss rate at 1973 K compared to the undoped coating, achieving a protection efficiency of 99.58 %. The performance enhancement is attributed to the in-situ formation of a self-generated glass phase during oxidation, which exhibits high fluidity and self-healing properties. Additionally, the in-situ precipitated nanoscale MoB phase effectively suppresses the volatilization of B 2 O 3 through a pinning effect, achieving a synergistic enhancement in thermal stability and oxygen blocking capabilities. Notably, excessive MoSi 2 doping at 50 vol% leads to detrimental effects. Intensified MoO 3 volatilization reduces the viscosity of the glass phase and triggers a chain reaction of defect propagation, consequently increasing the carbon loss rate by 34.43 % compared to ZZM40. The proposed powder-source in-situ alloying strategy validates the defect-repair mechanism driven by dual-silicide oxygen-blocking reinforcement, providing crucial theoretical foundations for the design and application of next-generation high-temperature thermal protection materials.