Effect of Boron Nitride Addition on Densification, Microstructure, Mechanical, Thermal, and Dielectric Properties of β-SiAlON Ceramic

In this present communication, an investigation was carried out to examine the influence of hexagonal boron nitride (h-BN) powder addition and its particle size on the density, microstructure, mechanical, thermal, and dielectric properties of h-BN containing β-SiAlON ceramic. It was observed that with the increase in BN content up to 5 wt.% in starting composition, the bulk density of β-SiAlON decreases drastically from 3.22  (for pristine SiAlON) to 3.05 g/cm3 and 2.90 g/cm3 for small and large particle size containing β-SiAlON, respectively. The bulk density and mechanical properties such as Young’s modulus, Vickers hardness, flexural strength, and fracture toughness of pristine β-SiAlON are superior in comparison with both types of β-SiAlON-BN ceramic. On the other side, the density and mechanical properties of β-SiAlON prepared with fine BN powder show superior value compared to that of larger BN particle-added β-SiAlON. The thermal properties such as thermal conductivity for both BN powder-added β-SiAlONs are higher compared to that of pristine β-SiAlON. However, larger BN particle-added β-SiAlON exhibits superior thermal conductivity than that of fine BN powder-added β-SiAlON. The dielectric constant of h-BN-added SiAlON is relatively lower than that of pristine β-SiAlON.