Powder Modification Facilitates the Sintering and Performance Optimization of Y 2 O 3 ‐MgO Nanocomposite Ceramics

Y 2 O 3 ‐MgO composite ceramics possess intrinsic advantages in the 3–5 µm mid‐infrared region, including theoretically high transmittance, high mechanical strength, and low emissivity, making them promising candidates for next‐generation infrared window materials for high‐speed flight applications. However, further process optimization is still required to improve their practical performance. In this study, YM composite powders were prepared via the glycine‐nitrate combustion method. A fluorination strategy was introduced for the first time through ball milling during powder processing. Combined gravimetric water vapor adsorption measurements and first‐principles calculations revealed that fluorination enhances the hydrophobicity of the powders, thereby improving resistance to moisture absorption of MgO. Sintering kinetics analysis further demonstrated that an appropriate level of fluorination promotes densification, suppresses grain growth, and consequently improves infrared transmittance. Overall, 0.05 wt% fluorination increases powder hydrophobicity by nearly 20%, enables a transmittance exceeding 80% in the 3–5 µm range, and achieves an average flexural strength of 375 MPa. To the best of our knowledge, this is the first systematic study on the preparation of fluorinated YM composite ceramics, providing a new perspective for processing optimization of this ceramic system.