Synthesis and properties of AlN/MAS/Si3N4 ternary glass-ceramic composites with in-situ grown rod-like β-Si3N4 crystals

The AlN/MAS/Si3N4 ternary composites with in-situ grown rod-like β-Si3N4 were obtained by a two-step sintering process. The microstructure analysis, compositional investigation as well as properties characterization have been systematically performed. The AlN/MAS/Si3N4 ternary composites can be densified at 1650 °C in nitrogen atmosphere. The in-situ grown rod-like β-Si3N4 grains are beneficial to the improvement of thermal, mechanical, and dielectric properties. The thermal conductivity of the composites was increased from 14.85 to 28.45 W/(m K) by incorporating 25 wt% α-Si3N4. The microstructural characterization shows that the in-situ growth of rod-like β-Si3N4 crystals leads to high thermal conductivity. The AlN/MAS/Si3N4 ternary composite with the highest thermal conductivity shows a low relative dielectric constant of 6.2, a low dielectric loss of 0.0017, a high bending strength of 325 MPa, a high fracture toughness of 4.1 MPa m1/2, and a low thermal expansion coefficient (α25-300 °C) of 5.11 × 10−6/K. This ternary composite with excellent comprehensive performance is expected to be used in high-performance electronic packaging materials.