Low-temperature solid reaction synthesis of high sinterability MgAl2O4 powder from γ-Al2O3+MgO and θ/α-Al2O3+MgO batches

摘要

? 2022 Elsevier Ltd and Techna Group S.r.l.By using nanometric γ-Al2O3+MgO and θ/α-Al2O3+MgO mixtures, two kinds of pure nanometric MgAl2O4 (MAS) powders were successfully synthesized in air at 1250 °C and 1200 °C for 60 min, respectively. The phase transformation and morphology evolution during heating of γ-Al2O3+MgO showed two MAS formation paths, i.e., γ/θ-Al2O3+MgO→MAS and α-Al2O3+MgO→MAS. As a result, the pure MAS powder synthesized by γ-Al2O3+MgO exhibited a bimodal aggregated particle size distribution. Correspondingly, the MAS powder from θ/α-Al2O3+MgO presented a unimodal aggregated particle size distribution. Further sintering experiments showed that the bimodal MAS powder prepared by γ-Al2O3+MgO had high sinterability as it can be consolidated to high relative density ceramics (99.80) at low temperature (1450 °C) for short dwelling duration (120 min) in air. Moreover, its sintered MAS ceramics also showed transparency in infrared range with the maximum transmittance of 63.8. The excellent sinterability of the bimodal MAS powder indicates that the proposed MAS synthesis method by using nanometric γ-Al2O3+MgO is helpful to fabricate MAS ceramics of high density.