Effect of composition on the dielectric properties and thermal conductivity of α-SiAlON ceramics

In this study, a series of dense Ym/3Si12-(m+n)Alm+nOnN16-n (m = 1.1-1.5, n = 1.0) ceramics were prepared by hot-pressing at 1900 degrees C for 1 h. The effects of composition on the thermal conductivity, dielectric, and wave-transparent properties of Y-alpha-SiAlON ceramics were investigated. The X-ray diffraction (XRD) results showed that all ceramic samples exhibited a pure alpha-SiAlON phase. The dielectric properties of Y-alpha-SiAlON at 1 kHz-120 MHz and 8.2-12.4 GHz were investigated. The results indicate that a smaller m value leads to weaker ion and interfacial polarisations, resulting in a lower dielectric constant. The three-dimensional relationship between microwave transmittance, frequency, and sample thickness was calculated by simulation, and the results showed that Y0.40Si9.8Al2.2O1.0N15.0 had the best wave-transparent properties. The thermal conductivity of the Y-alpha-SiAlON ceramics showed a decreasing trend with increasing m value and temperature. The single-phase dense Y0.50Si9.5Al2.5O1.0N15.0 exhibited the minimum thermal conductivity, which was 9.75-5.21 W/m center dot K (20-1000 degrees C). Therefore, Y-alpha-SiAlON ceramics are expected to be promising high-temperature window materials owing to their excellent thermal insulation and wave-transparent properties.

Automated summary

This study investigates the effects of composition on the thermal conductivity, dielectric, and wave-transparent properties of Y-alpha-SiAlON ceramics. The experimental results show that these ceramics exhibit excellent thermal insulation and wave-transparent properties, making them promising high-temperature window materials.