Synthesis and characterization of W-Y2O3 composites with core-shell structure via wet chemical method in an acidic solution

Abstract

W-Y2O3 materials are the ideal PFMs in fusion reactors because of their excellent performance, however, due to the limitation of traditional powder preparation methods, W-Y2O3 materials face the challenges of coarse particles, high brittleness and low strength, and cannot meet the applications. The synthesis of high-quality powder is the first and crucial step in preparing high-performance tungsten based materials. Therefore, in this manuscript, W-Y2O3 powders with a nano and core-shell structure were synthesized by wet-chemical method in an acidic solution, and then the fine-grained W-Y2O3 composites was fabricated by spark plasma sintering (SPS) under 1873 K. The performance of W-Y2O3 composites and powders were analyzed by XRD, SEM and TEM. In particular, the existence form, distribution characteristics, evolution behavior of the second phase of Y2O3 and the interface characteristics of W/Y2O3 in powders and bulks were systematically discussed. H+ makes the self-assembly be inhibited in sol and produces the holes on surface of precursor powder during the reduction reaction. This structure of the precursor powder creates lots of paths which allow H2 to react with deep particles, resulting in ultrafine particle size, a core-shell structure and uniform element distribution. The powder of W-Y2O3 show obvious core-shell structure, and the thickness of the shell structure is uneven, about 7.7–15.2 nm, while the average grain size of these powders is 62.7 nm. Meanwhile, the W-Y2O3 alloys prepared from these powders show refinement and uniformity, the average grain size is 700 nm. Moreover, the new phase of Y2WO6 was observed at the W/Y2O3 interface, which has a semi-coherent relationship with Y2O3 and W, respectively. This is very conducive to improving the W/Y2O3 interface and thus significantly improving the performance. These results indicate that wet-chemical method in an acidic solution is a promising way to approach for synthesizing nano W-Y2O3 powders with core-shell structure and improve W/Y2O3 interface performance.