Yiling Huang

Molten silicates can be immobilized by protective reaction products or continue to penetrate oxide ceramics, but the structural features that distinguish these pathways remain unclear. Here we examine CMAS reactions with RETa ₃ O ₉ and connect crystallographic cation partitioning in corrosion products with passivation across rare‐earth chemistry, melt composition, and multicomponent design. EuTa ₃ O ₉ forms a durable bilayer comprising a dense AX ₂ O ₆ barrier and a cation‐sequestering B ₂ Y ₂ O ₇ layer; a related consumption–barrier architecture persists in Fe‐rich lunar‐ and Martian‐regolith analogue melts. Across 11 RETa ₃ O ₉ compositions, rare‐earth size acts as a structural descriptor for access to AX ₂ O ₆ ‐, B2Y2O ₇ ‐, and CZO ₄ ‐containing reaction pathways. Using this relationship as a design constraint, Eu‐centred high‐entropy RETa ₃ O ₉ compositions retain resistance to bulk penetration while reducing thermal conductivity. HEC‐2 forms an 84.4 µm reaction layer after 100 h at 1300°C and exhibits an 8.3% lower calculated effective thermal conductivity than EuTa ₃ O ₉ at 1200°C. These results link reaction‐product chemistry to mechanism‐constrained composition design for high‐temperature protective ceramics.

Rare‐earth silicates (RE ₂ Si ₂ O ₇ and RE ₂ SiO ₅ ) are leading candidates for third‐generation environmental barrier coatings (EBCs) because they combine corrosion resistance to molten calcium–magnesium–aluminosilicate (CMAS) and high‐temperature water vapor with thermal expansion coefficients (CTEs) compatible with ceramic matrix composites (CMCs), high melting points, phase stability, and low thermal conductivity. Their composition–structure–property relationships nevertheless impose coupled constraints: a composition that stabilizes a desirable phase or lowers thermal conductivity does not necessarily maximize water‐vapor and CMAS resistance, and plasma‐sprayed coatings can differ substantially from dense bulk ceramics because of SiO ₂ loss, amorphous phases, porosity, and segregation. Therefore, this review: (i) clarifies phase‐formation rules and their thermodynamic/crystallographic basis, (ii) compares single‐component and multicomponent silicates while distinguishing bulk and coating evidence, and (iii) summarizes environment‐dependent corrosion mechanisms and multi‐objective design strategies.

Although the f‐ratio method effectively eliminates the influence of beam current fluctuations in scanning electron microscope/energy dispersive spectroscopy (SEM‐EDS) quantitative analysis, its practical application remains strictly limited by the reliance on time‐consuming Monte Carlo (MC) simulations. To overcome this fundamental computational bottleneck, a novel fast f‐ratio quantification method combining the XPP analytical model with a dynamic iterative numerical algorithm is proposed in this work. By substituting the MC simulation with the XPP model, the computation time for theoretical intensities is drastically reduced from hours to milliseconds. Experimental validations performed on binary systems (CdSe, InAs, and ZnSe) and a ternary mineral (FeAsS) demonstrate that the proposed method achieves a remarkably low quantification error ranging from 0.6% to 2.8% after merely a few iterations, completely circumventing the requirement of a preset standard database. In summary, this study provides a new framework for real‐time, high‐precision standardless or standard‐limited EDS quantitative analysis.

Designing thermal barrier coatings (TBCs) with intrinsic resistance to calcium–magnesium–aluminosilicate (CMAS) corrosion requires mechanistic insight spanning atomic to mesoscale levels. Here we resolve the corrosion behavior of a high‐entropy rare‐earth cerate–zirconate, (Nd _1/5 Sm _1/5 Eu _1/5 Gd _1/5 Lu _1/5 ) ₂ ZrCeO ₇ (HEZC), by integrating EBSD, SPED, HAADF‐STEM, atomic‐resolution STEM–EDS, iDPC‐TEM, and in situ XRD. Multi‐scale analyses reveal that CMAS infiltration triggers rapid apatite formation at the interface, accompanied by the emergence of multi‐element‐doped fluorite‐type ZrO ₂ alternating along the corrosion frontier. This alternating architecture impedes melt penetration, yielding exceptional corrosion resistance—only 79.6 µm degradation after 50 h at 1300°C and 45.1 µm after 10 h at 1350°C. Atomic‐scale mapping and first‐principles calculations show that Ca preferentially occupies AO ₉ polyhedra in the apatite lattice, while the high configurational entropy of the rare‐earth sublattice destabilizes corrosion products, collectively suppressing frontier advance. These results establish a mechanistically validated design framework in which mixed‐valent Ce and rare‐earth–site entropy act synergistically to govern CMAS–TBC interactions, guiding the development of next‐generation, entropy‐stabilized coatings for sustained operation above 1300°C.

Scanning electron microscopy (SEM) during thermal-shock durability testing of thermal barrier coatings (TBCs) is limited to a few checkpoints, which limits microstructural evolution analysis due to sparse imaging data. Here we present FracFlowFormer, a data-efficient forecasting framework that learns from limited early-stage SEM observations and predicts late-stage fracture and pore evolution in TBCs. To address the issue of coarse temporal sampling, we reconstruct more densely sampled temporal sequences employing TV-L1 dense optical-flow interpolation, thereby generating intermediate states that maintain fracture- and pore-relevant morphology. FracFlowFormer forecasts subsequent microstructural evolution using a hybrid architecture that combines a U-Net encoder–decoder and a spatio-temporal fusion transformer for long-range temporal SEM image generation, enabling high-fidelity predictions that capture microstructural evolution in TBCs during thermal-shock cycling, with 89.95% SSIM, 0.049 LPIPS, and 23.18 dB PSNR. An optical-flow branch provides a microstructural evolution cue that complements grayscale appearance and temporal aspects information. The framework reconstructs high-fidelity, time-resolved image sequences from sparse early-stage observations and demonstrates descriptor-based characterization of microstructural evolution, thereby transforming TBC characterization from static inspection into evolution-aware analysis of degradation and failure.

In this research, a novel method for regulating components in RE₂SiO₅/RE₂Si₂O₇ multiphase silicates was developed, combining the benefits of suitable thermal expansion coefficient (CTE) and outstanding corrosion resistance against calcium-magnesium-alumino-silicate (CMAS). This approach enhanced the overall thermophysical properties. Additionally, the results from the CMAS corrosion resistance test indicated that (Lu_1/3Yb_1/3Tm_1/3)₂SiO₅/(Lu_1/3Yb_1/3Tm_1/3)₂Si₂O₇ and (Lu_1/4Yb_1/4Tm_1/4Er_1/4)₂SiO₅/(Lu_1/4Yb_1/4Tm_1/4Er_1/4)₂Si₂O₇ exhibited exceptional resistance to CMAS penetration, even at temperatures up to 1500 ℃. To comprehend the corrosion mechanism of CMAS on these silicates, we introduced a reaction-diffusion model, which involved observing interface changes between the corrosion product layer and the silicate block. This was achieved using Electron Back Scatter Diffraction (EBSD). These findings lay a theoretical basis for selecting rare earth elements in RE₂SiO₅/RE₂Si₂O₇ multiphase silicates based on the radius of different rare earth cations.

Atmospheric plasma spray (APS) yttria-stabilized zirconia coatings have a complex microstructure with a variety of pores that significantly reduce the thermal conductivity. APS thermal barrier coatings (TBCs) with a similar monoclinic phase were prepared. The pore sizes and distributions of the coatings were obtained by scanning their cross-section via SEM; the scanned areas were over 1 mm × 2 mm and more than 23,000 pores for each coating were analyzed. Multiple linear regression was used to analyze the porosity data and then to determine the quantitative relationship between different types of pores and thermal conductivity. Results revealed that the different pores have different effects on decreasing the thermal conductivity. The small, vertical pores have the biggest effect, while the horizontal pores also play a significant role in decreasing the thermal conductivity.