Materials scientists have been exploring environmental barrier coatings (EBCs) materials that can withstand stable operation in oxidizing environments containing water vapor at temperatures of 1400 ℃ and above, to protect SiC ceramic matrix composites from corrosion.
Recently, a team of material scientists led by Prof. Guifang Han from Shandong University, China first reported MoSi2/HfO2 duplex EBCs prepared on SiC substrates which was demonstrated to provide effective protection against detectable corrosion in a 1500 °C steam environment for at least 200 h. The formation of tri-layered TGOs structure between the MoSi2 and HfO2 layers was identified as the key protective mechanism.
The team published their work in Journal of Advanced Ceramics on May 23, 2025.
"In this report, we employed EPMA, micro-area XRD, Raman spectroscopy, and TEM to carefully identify the composition and phase structure of the tri-layered TGOs, which were composed of α-cristobalite, Hf-doped SiO2 glass, and Hf-Si-O glass, embedded with HfSiO4 and HfO2 particles."said Dr. Guifang Han，the corresponding author of the paper, a professor in the School of Materials Science and Engineering at Shandong University.
"The interdiffusion of Hf and Si between the HfO2 and SiO2 layers generated an in-situ formed gradient glassy phases, which were found to offer a crack-blocking effect that prevented the propagation of channel cracks through the TGOs layer. Simultaneously, the flowing behaviour of glasses inside TGOs at high temperatures facilitated the filling of pores within the HfO2 layer, promoting the densification of coatings and self-healing of cracks." said Dr. Guifang Han.
"This study demonstrates that in-situ gradient Hf doping can effectively constrain the crystallization of SiO2 of EBCs system at high temperatures. Additionally, the formation of multilayer structure TGOs containing both crystalline and amorphous phases mitigates channel cracks caused by the cristobalite phase transformation, thereby eliminating rapid oxidant transport pathways through the coating." said Dr. Guifang Han.
"This work provides a novel strategy to simultaneously enhance TGOs stability and elevate the operation temperature of EBCs, which contributes to the development of next-generation EBCs systems with extended service lifetimes and improved thermal capabilities." said Dr. Guifang Han.
However, more delicate research works are still needed to improve the adhesion strength and thermal cycle stability of the EBCs.
Other contributors include Kexue Peng, Ying Qiao, Qian Li, Long Wang, Jingyu Qin and Jingde Zhang from the School of Materials Science and Engineering, Shandong University, China; Xinxin Cao from Institute of Materials, Shanghai University, China; Jianzhang Li, Xi'an Golden Mountain Ceramic Composites Co., Ltd., China.
This work was supported by the Creative Research Foundation of the Science and Technology on Thermostructural Composite Materials Laboratory (No. 2023-JCJQ-LB-071-01-01).
About Author
Guifang Han, currently a professor and doctoral supervisor at the School of Materials Science and Engineering, Shandong University. She mainly engages in the design, preparation, and performance evaluation of ultra-high temperature ceramic materials and coatings for extreme environments, additive manufacturing of ceramic materials, and research on structure-function integrated materials. She has published around 100 papers in journals such as Progress in Materials Science, Nature Communications, Journal of Advanced Ceramics, and Corrosion Science, and has been cited more than 3000 times.
About Journal of Advanced Ceramics
Journal of Advanced Ceramics (JAC) is an international academic journal that presents the state-of-the-art results of theoretical and experimental studies on the processing, structure, and properties of advanced ceramics and ceramic-based composites. JAC is Fully Open Access, monthly published by Tsinghua University Press, and exclusively available via SciOpen . JAC's 2023 IF is 18.6, ranking in Top 1 (1/31, Q1) among all journals in "Materials Science, Ceramics" category, and its 2023 CiteScore is 21.0 (top 5%) in Scopus database. ResearchGate homepage: https://www.researchgate.net/journal/Journal-of-Advanced-Ceramics-2227-8508
