Conventional forming methods for MgAl 2 O 4 (MAS) ceramics struggle to fabricate complex geometries and face the inherent trade-off between densification and grain growth, while SLA-printed MAS have rarely matched the mechanical properties of their conventionally sintered counterparts. This work proposes an integrated strategy that combines stereolithography (SLA) 3D printing, pressureless sintering, and Y 2 O 3 -induced in-situ Y 3 Al 5 O 12 (YAG) phase formation. Unlike conventional doping studies, we systematically quantified the grain-boundary pinning effect using the Smith–Zener model. As the Y 2 O 3 content increased from 2 to 10 wt%, the YAG content correspondingly rose from 3.3 to 18.0 wt%, and the theoretically predicted limiting grain size of MAS first decreased from 48.09 to 8.04 μm, and then increased to 11.81 μm. The variation trend shows good consistency with the experimentally observed grain size evolution. At an optimal Y 2 O 3 content of 4 wt%, the ceramic achieved a high densification (apparent porosity 0.17%, bulk density 3.48 g cm -3 ), a flexural strength of 256.49 MPa, and a critical thermal shock temperature (ΔT c ) of 214.94 °C. The synergy between SLA and in-situ YAG pinning enables the fabrication of complex-shaped, high-strength, thermally stable MAS components, offering new insights for the development of high-performance engineering ceramics.
This study fabricated translucent alumina ceramics with varying MgAl 2 O 4 doping concentrations using vat photopolymerization (VPP) additive manufacturing combined with vacuum sintering. The influence of MgAl 2 O 4 content on the microstructure, mechanical properties, and optical characteristics was comprehensively investigated. Results demonstrate that optimal MgAl 2 O 4 doping (0.2 wt%) significantly enhances material densification, achieving superior mechanical performance with a flexural strength of 510 ± 30 MPa and fracture toughness of 3.7 MPa m 1 / 2 after sintering at 1700 °C, alongside improved optical transmittance. Microstructural characterization demonstrates that the MgAl 2 O 4 sintering additive promotes densification and grain refinement through effective suppression of abnormal grain growth and pore formation.
The dry reforming of methane (DRM) could convert CH 4 and CO 2 into syngas, offering potential for greenhouse gas mitigation. However, DRM catalyst sintering and carbon deposition remain major obstacles. In this study, a highly dispersed PtNi alloy@Zr-doped 3D hollow flower-like MgAl 2 O 4 (AMO) spheres was prepared through a hydrophobic driving strategy. During a 50-hour test at 550 °C, the catalyst exhibited no significant decline in CH 4 and CO 2 conversion rates, demonstrating its excellent anti-sintering and anti-coking performance. The unique anti-coking performance can be attributed to Zr-induced oxygen vacancies, which enhance oxygen mobility and reduce carbon deposition. Besides, doped Zr increases basic active sites, enhancing CO 2 adsorption and activation, thus accelerating carbon species conversion. At 700 °C, the unique synergy between highly dispersed Pt and Ni enabled CH 4 and CO 2 conversion rates to reach 67.5 % and 73.8 %, respectively. The incorporation of Pt or Zr extends the Ni–Ni bond and partially coordinates with Ni, enhancing the stability of the Ni lattice. The reaction of CH 4 and CO 2 follows the Langmuir-Hinshelwood (L-H) mechanism, where both reactant molecules are adsorbed and activated on the metallic sites. Moreover, the effective energy barrier for the CH oxidation pathway is lower by 0.16 eV than that for the C oxidation pathway, which helps suppress the formation of carbon deposits.
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