Powder Optimization Strategies for Binder Jetting Printing of BaTiO ₃ and Ba ₀,₆ Sr ₀,₄ TiO ₃ Ceramics

Barium titanate (BT) and barium–strontium titanate (BST) are key ferroelectric ceramics for electronics and power electronics applications, where complex geometries can significantly enhance functional performance. Binder jetting (BJ) powder bed additive manufacturing offers a promising route to fabricate such architectures, provided that powder properties are carefully tailored. In BJ, powder flowability and binder compatibility are critical and often antagonistic parameters. In this work, commercial BT and BST powders are systematically characterized with respect to particle size distribution, flowability, and binder interaction. Granulated BST powders (D50 ∼20 µm) exhibit excellent flowability (Hausner index H ∼1.3) but poor binder affinity, leading to fragile green bodies. Conversely, fine nongranulated powders (D50 ≈ 4.4 µm) show strong binder interaction but poor flowability (H ∼2.3), limiting powder bed stability. Two strategies are investigated to overcome these limitations: (i) impregnation of granulated powders with an aqueous binder and (ii) addition of fumed silica (0.5–2 wt%) to fine powders. Binder impregnation increases BST green density up to 31.3%, while 1.25 wt% SiO 2 improved BT flowability ( H ∼1.9) and enabled stable green parts with green densities up to 32.6%. This work demonstrates the critical interplay between powder flowability and binder compatibility in BJ for complex dielectric ceramics.