Alumina (Al₂O₃) ceramics represent a crucial category of advanced structural engineering materials due to their excellent physicochemical properties and relatively low cost. However, their broader application has been limited by low fracture toughness, making toughening a key research focus for Al₂O₃ ceramics. Silicon carbide whiskers (SiC w ) are among the most effective toughening agents for Al₂O₃ ceramics, but recent studies have primarily focused on optimizing SiC w introduction methods and sintering processes. Departing from conventional approaches, the present research has pioneered a novel strategy—designing a core-shell composite structured SiC w as the toughening phase for Al₂O₃ ceramics, thus offering a new perspective for Al₂O₃ ceramic toughening studies.
A research team led by materials scientist Zhang Zhixiao from Hebei University of Engineering in Handan, China, has recently successfully fabricated an Al₂O₃ composite ceramic toughened by TiC-coated SiC w (SiC w @TiC) core-shell structured whiskers and investigated the formation mechanism, microscale stress distribution, and toughening mechanism of these core-shell whiskers within the ceramic matrix.
Their findings were published in the Journal of Advanced Ceramics on June 18, 2025.
“We prepared the SiC w @TiC core-shell structured whisker-toughened Al₂O₃ composite ceramics via molten salt synthesis followed by spark plasma sintering. Unlike conventional single-phase SiC w toughening, the unique core-shell architecture—where micron-sized SiC whiskers are fully encapsulated by a TiC shell (~85 nm thick) composed of nanoparticles—creates multiscale heterogeneity (Al₂O₃/SiC/TiC phase mismatch, micro/nano grain size differences, and thermal expansion contrasts). This complex microstructure generates intricate stress fields that activate multiple energy-dissipation mechanisms, significantly boosting the composite’s fracture toughness.” stated Dr. Zhixiao Zhang, corresponding author of the paper, a professor in the College of Materials Science and Engineering at Hebei University of Engineering. Professor Zhang is also the Top-notch Talent in Hebei Province of China and Director of the Analysis and Testing Experiment Center at Hebei University of Engineering.
The SiC w @TiC core-shell structured whiskers exhibit dual-scale toughening behavior. When treated as an integral unit, they trigger classical mechanisms like crack deflection, whisker bridging, and fracture—similar to single-phase SiC w -reinforced Al₂O₃. However, when regarded as a composite structure, the whiskers introduce additional crack propagation paths and induce counter-propagating cracks along the SiC w -TiC interface. This multidimensional crack evolution stems from the whiskers’ complex stress environment, engineered by their unique geometric structure and multiscale heterogeneity. As a result, the Al₂O₃-SiC w @TiC composite ceramic achieves a remarkable fracture toughness of 7.15 ± 0.47 MPa·m 1/2 , surpassing conventional Al₂O₃-SiC w composites.
“This work extends our earlier success with B₄C@TiB₂ core-shell particle-toughened Al₂O₃ ceramics, but it’s far more than a simple phase substitution” Zhang noted. “Instead, it achieves the cross-dimensional transformation of composite toughening phase with a core-shell structure from 0D particles to 1D whiskers, offering a transformative solution to overcome current bottlenecks in Al₂O₃-SiC w toughening research.”
Moving forward, the team plans to systematically explore core-shell structured toughening phases with varied compositions (e.g., B₄C, TiB₂, SiC, Si₃N₄) and morphologies (expanding from 0D particles and 1D whiskers to 2D sheet-like structures) for diverse ceramic matrices. Their ultimate goal is to establish a unified theoretical framework for toughening ceramic matrices using core-shell structured toughening phases.
Other contributors include Weixing Li, Huijuan Pang, Liyuan Cheng, Yafeng Wang, Xiaoliang Zhang, Jingbo Mu, Yanming Wang, Xiaorong Zhang from Hebei University of Engineering, Handan, China; and Yu Dong from Curtin University, Perth, Australia.
This work was financially supported by the Central Government Guided Local Science and Technology Development Fund Project (No. 226Z1101G), the Science and Technology Research Project of Universities in Hebei Province (No. CXY2024033), and the Hebei Yanzhao Golden Platform backbone Talent Project (Platform for returning to China) (No. A2024008).
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 2024 IF is 16.6, ranking in Top 1 (1/33, Q1) among all journals in “Materials Science, Ceramics” category, and its 2024 CiteScore is 25.9 (5/130) in Scopus database. ResearchGate homepage: https://www.researchgate.net/journal/Journal-of-Advanced-Ceramics-2227-8508
Journal of Advanced Ceramics
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