The fabrication of SS (stainless steel)-UO₂ cermet-type advanced nuclear fuel pellets suitable for use in power reactors depends on the development of metallic (SS), ceramic (UO₂), and cermet (SS-UO₂) microspheres with special characteristics. In this work, a nonconventional powder metallurgy process was developed to produce porous SS microspheres aiming to contribute to solve the bottlenecks found in the SS-UO₂ cermet pellet manufacturing. SS, UO₂, and SS-UO₂ microspheres and SS-UO₂ cermet pellets were fabricated and characterized (XRD, EDX, EDS, and SEM). Hard (153 ± 5 µm; 132.2 ± 24.7 MPa; 72% TD) and soft (216 ± 10 µm; 1.3 ± 0.4 MPa; 17% TD) SS, hard (176 ± 6 µm; 147.4 ± 25.0 MPa; 99% TD) UO₂, and cermet (SS-UO₂) microspheres were obtained. The soft porous SS microspheres did not micronize properly in situ, but their high compressibility favors the compaction of the green SS-UO₂ cermet pellet; in this pellet, the UO₂ microspheres behaved as rigid inclusions. This favored the obtainment of sintered SS-UO₂ cermet pellets with high geometric densities (93% TD), excellent metal–ceramic interaction, and the preservation of the physical integrity of the UO₂ microspheres. The usage of high fractions of the SS-UO₂ cermet microspheres obtained mixed with low fractions of the said soft porous SS microspheres is already under development. This will enable the fabrication of SS-UO₂ cermet pellets with a volume fraction greater than 42 vol% UO₂, a homogeneous distribution of UO₂ microspheres in the metallic matrix, and null connection between them. The oxide–metal reduction mechanisms were discussed. The applicability of the process is already being explored in the manufacture of porous NdFeB microspheres.

中文翻译：

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用于金属陶瓷型先进核燃料制造的非常规粉末冶金工艺合成多孔不锈钢微球

适用于动力反应堆的 SS（不锈钢）-UO ₂金属陶瓷型先进核燃料芯块的制造取决于金属（SS）、陶瓷（UO ₂）和金属陶瓷（SS-UO ₂）微球的开发特色。在这项工作中，开发了一种非常规的粉末冶金工艺来生产多孔 SS 微球，旨在帮助解决 SS-UO ₂金属陶瓷颗粒制造中发现的瓶颈。制造并表征了SS、UO ₂和 SS-UO ₂微球以及 SS-UO _{2金属陶瓷颗粒（XRD、EDX、EDS 和 SEM）。}硬（153 ± 5  µm；132.2 ± 24.7 MPa；72% TD）和软（216 ± 10 微米；1.3±0.4兆帕；获得17% TD) SS、硬 (176 ± 6  µm；147.4 ± 25.0 MPa；99% TD) UO ₂和金属陶瓷 (SS-UO _{2 ) 微球。}柔软的多孔 SS 微球不能原位微粉化，但它们的高压缩性有利于绿色 SS-UO ₂金属陶瓷颗粒的压实；在此颗粒中，UO ₂微球表现为刚性夹杂物。这有利于获得具有高几何密度 (93% TD)、出色的金属-陶瓷相互作用以及保持 UO _{2微球物理完整性的烧结 SS-UO 2}金属陶瓷颗粒。使用高分数的 SS-UO ₂与低比例的所述软多孔SS微球混合获得的金属陶瓷微球已经在开发中。这将能够制造体积分数大于 42 vol% UO _{2的 SS-UO 2金属陶瓷颗粒、UO 2}微球在金属基体中的均匀分布以及它们之间的零连接。讨论了氧化物-金属还原机制。该工艺的适用性已经在多孔 NdFeB 微球的制造中得到探索。