Design of Micro/Nano-Lamellar C₄AcH₁₁ and Hydrotalcite in Alumina-Spinel Castables: Enhanced High-Temperature Damage Resistance

Abstract

In the present study, lamellar hydrates were designed via curing regimes and additives. Structural and high-temperature fracture behavior analyses were employed to elucidate the influence of initial lamellar hydrates on microstructural evolution and thermal stress resistance at elevated temperatures. Key findings reveal that: Pure CAC cured at 25 °C for 24 h predominantly forms metastable CAH10 and C2AH8, whereas under the two-step curing regime, the hydration products are granular C3AH6 and lamellar AH3. Incorporating CaCO3 and MgO under two-step curing promotes the simultaneous generation of micro/nano-lamellar C4AcH11 and Mg-Al Hydrotalcite (M-A-H). The enhanced extent of hydration and pore-filling effect of M-A-H refines matrix porosity, increasing the volume fraction of 5–100 nm pores and elevating the fractal dimension (Ds). This microstructural optimization improves bonding strength, as evidenced by an 82% increase in demolding strength in the designed samples compared with the R samples. C4AcH11 and M-A-H serve as reactive CaO and MgO sources, respectively, facilitating the interlocking distribution of in-situ CA6 and MgAl2O4 at 1600 °C and optimizing pore structure. The hierarchical pore structure and refined crystals synergistically enhance thermal stress resistance by increasing crack deflection, dissipating energy, and improving plastic deformation capacity.

Keywords

Micron/nano lamellar hydrates / Initial hydration phases / Pore structures optimization / High- temperature fracture behavior

Statement of the Use of Generative AI and AI-Assisted Technologies in the Writing Process

Specifically, we have used DeepSeek (Version [DeepSeek-V3]) for English translation and language polishing during the preparation of this manuscript. All AI-generated content has been thoroughly reviewed, verified, and edited by us. We take full responsibility for the accuracy and integrity of the content.

Author Contributions

Conceptualization, Y.L. and S.J.; Methodology, N.L. and W.L.; Software, W.L.; Validation, G.H., W.L.; Formal Analysis, Y.L.; Investigation, N.L.; Resources, S.J.; Data Curation, G.H.; Writing-Original Draft Preparation, G.H.; Writing-Review & Editing, N.L.; Visualization, G.H.; Supervision, Y.L.; Project Administration, N.L.; Funding Acquisition, S.J.

Ethics Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

All data generated or analyzed during this study are completely presented within the published article. No external datasets were generated or deposited in public repositories, and no additional data links are required.

Funding

This research was funded by [Hubei Provincial Special Fund for Central-Guided Local S&T Development] grant number [2025CSA017]. The APC was also funded by [Hubei Provincial Special Fund for Central-Guided Local S&T Development].

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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