Eco-Friendly Fabrication of High-Performance Si3N4 Ceramic Substrates via Aqueous Tape Casting and Reaction-Bonding Sintering: Effects of α-Si3N4 Seeding

This study presents a cost-effective and environmentally friendly approach for fabricating large-area, low-defect Si₃N₄ ceramic substrate materials using tape casting combined with reaction-bonding sintering at 1900 °C. High-purity Si powder and a non-toxic Duramax™ B-1000 binder system were employed as raw materials. Orthogonal experiments (L9(3 4 ) array) optimized key parameters: 45 wt% solid content, 12.0 wt% binder, 0.4 wt% ammonium citrate dispersant, and a PEG-600 plasticizer to binder ratio (R) of 0.7. These conditions produced defect-free green tapes with smooth surfaces, minimal shrinkage, and balanced strength-flexibility properties. During re-sintering, the addition of 4 wt% Si 3 N 4 seeds maximized performance, yielding ceramics with 92.69% relative density, 15.6 GPa Vickers hardness, 6.6 MPa·m 1/2 fracture toughness, 636.1 MPa flexural strength, and 60.74 W·m −1 ·K −1 thermal conductivity. Microstructural analysis revealed elongated β-Si 3 N 4 grains, confirmed by XRD. This work demonstrates a scalable fabrication route for high-performance Si 3 N 4 substrates using economical and eco-conscious processing.