Deagglomeration‐Enhanced Sinterability of Y ₂ O ₃ ‐MgO Nanopowders for Pressureless Presintering of Nanocomposite Ceramics

ABSTRACT Y 2 O 3 ‐MgO nanocomposite ceramics are promising candidates for high‐performance windows as well as many other applications due to their exceptional optical and mechanical properties, particularly under harsh environments. Realizing these applications, however, requires full densification and a uniform, fine‐grained microstructure. In this study, Y 2 O 3 ‐MgO nanopowders with an average primary crystallite size of 6.6 nm were synthesized via a sol‐gel combustion method. We tailored the agglomeration state of the as‐synthesized powders through a dedicated deagglomeration treatment and systematically investigated its impact on microstructural evolution during pressureless sintering. The results demonstrate that proper deagglomeration treatment markedly improved powder dispersion, which consequently enhanced sinterability. This led to a dramatic increase in the relative density of the ceramic, from 64.5% to 97.3%, after pressureless sintering at 1400°C. Furthermore, a highly dense (95.2%) Y 2 O 3 ‐MgO nanocomposite with a fine grain size of 114 nm was achieved by pressureless sintering at a reduced temperature of 1300°C for 1 h, rendering it an ideal precursor for subsequent hot isostatic pressing.