Journal of the American Ceramic Society最新文献

J Am Ceram Soc. 2024;107:7460–7469.

https://doi.org/10.1111/jace.20032

These corrections do not affect the data interpretation, discussion, or conclusions of the paper. The authors apologize for these errors and any inconvenience they may have caused.

To address the challenge of inefficient synthesis of multi-principal-element transition metal carbides, this study demonstrates an efficient pathway using ultrafast high-temperature sintering (UHS) to convert elemental precursors into dense, 2- to 9-component solid solutions within minutes. Rapid densification results from a synergy between the high heating rate of UHS and the formation of a Cr₃C₂-based liquid phase. The formation of a single-phase solid solution is governed by a thermo-kinetic control mechanism, where thermodynamic drivers are ultimately constrained by kinetic barriers, such as the poor solubility of key components (e.g., ZrC) and the diffusion-facilitating role of carbon vacancies. The resulting solid solutions exhibit excellent hardness (up to 38.6 GPa), but their fracture toughness is limited by process-induced thermal stresses, a drawback partially mitigated by post-sintering annealing. This work presents a promising approach for the high-throughput fabrication and screening of these materials and provides critical insights into their non-equilibrium sintering mechanisms.

The phase diagram of the GeO₂–CaO system was investigated using differential thermal–thermogravimetric analysis and the equilibration–quenching technique, followed by electron probe microanalysis and X-ray diffraction. The Ca₂Ge₇O₁₆ compound was confirmed to be stable, and a eutectic reaction of L → GeO₂(hex) + Ca₂Ge₇O₁₆ was identified in the GeO₂-rich region. Based on the previous and present experimental data for the GeO₂–CaO system and reliable literature data for the GeO₂–SiO₂ system, thermodynamic optimization of both binaries was carried out. The GeO₂–SiO₂ system was reoptimized to ensure internal consistency and improved agreement with experimental data relative to the previous assessment, based on refinements to the heat capacity of GeO₂ and the quartz solid-solution model. The liquid phase was modeled using the Modified Quasichemical Model, and the quartz solid solution in the GeO₂–SiO₂ system, in which Si⁴⁺ and Ge⁴⁺ cations are mixed over a single sublattice, was described using the Compound Energy Formalism. A single set of self-consistent Gibbs energy functions for all phases in the GeO₂–CaO and GeO₂–SiO₂ systems was obtained, reproducing phase equilibria and thermodynamic properties over wide composition and temperature ranges. The optimized database provides a reliable foundation for thermodynamic modeling of GeO₂–CaO–SiO₂ ternary and multicomponent oxide systems relevant to metallurgical recycling as well as ceramic-glass design and processing.

Multi-rare-earth-principle-component disilicates ((nRE_x)₂Si₂O₇) are advanced candidates for the environmental barrier coatings (EBCs) materials, wherein the multicomponent design strategy is used to achieve synergistic optimization on various material properties. In this study, two (nRE_x)₂Si₂O₇ materials, that is, β-(Gd_0.15Ho_0.15Yb_0.35Lu_0.35)₂Si₂O₇ and γ-(Gd_0.15Ho_0.35Yb_0.35Lu_0.15)₂Si₂O₇ with distinct polymorphic structures are designed by exquisitely tuning the relative ratio of the four constituent rare-earth elements. The two samples exhibit good stability of β or γ phase, low thermal conductivity, and coefficients of thermal expansion in good compatibility with the silicon carbide fiber-reinforced silicon carbide ceramic matrix composites. The corrosion depth of β-(Gd_0.15Ho_0.15Yb_0.35Lu_0.35)₂Si₂O₇ and γ-(Gd_0.15Ho_0.35Yb_0.35Lu_0.15)₂Si₂O₇ samples after the completeness of CMAS corrosion process at 1300°C are approximately 428.33 and 239.70 µm, respectively. Such different corrosion behaviors have been attributed to the increased concentration of active elements (e.g., Ho), which serves multiple functions by accelerating apatite formation, consuming molten CMAS, decreasing the Ca/Si ratio, and significantly mitigating the activity of corrosion reactions. These results are expected to enlighten the synergistic optimization of thermo-physical properties and corrosion resistance of (nRE_x)₂Si₂O₇ materials by compositional modulation, and provide important guidelines for the design and screening of advanced EBC materials.

The precise regulation of the dissolution and ion release of borate-based glasses is essential for optimizing their potential in various applications, including antimicrobial materials, angiogenesis, and resorbable medical uses. However, the multicomponent interactions among network modifiers that govern these behaviors remain insufficiently resolved. In this study, a composition-response mapping strategy was employed to systematically evaluate 16 multicomponent borate networks. Utilizing a design-of-mixture (DoM) approach, the individual and interaction effects of the modifiers were examined with respect to mass loss and ion release kinetics under simulated physiological conditions. This approach delivers a composition-response map for the studied system and a mechanistic foundation to expedite the development of borate-based formulations. The extent of dissolution varied from 20%–72% at 10 min to between 85% and 100% at 24 h. Statistical modeling indicated that dissolution is governed by modifier synergy rather than by concentration alone. For example, Ca²⁺ moderated reactivity, F⁻ suppressed long-term mass loss, and Ag⁺ accelerated ion exchange. The distinct kinetic profiles for the release of B, Ca, Ag, and F demonstrated compositionally adjustable transitions between transient and relatively more stabilized dissolution states. Collectively, these data establish a comprehensive map linking composition to function, enabling precise control over the degradation and ion-release behavior. This framework enables the rational engineering of borate-glass biomaterials that resorb with defined kinetics and can be functionally tailored for various therapeutic applications.