Enhancing the Optical Properties of α-SiAlON Ceramics Using Two-Stage High Energy Milling Method

In this study, semi-transparent Dy/Y-alpha-SiAlON ceramics were produced using spark plasma sintering (SPS) technique. The effects of the production of the initial powder mixture by two-stage high-energy milling method on the phase composition, microstructure and optical properties of translucent alpha-SiAlON ceramics were investigated. In the first stage of the milling process, it was aimed to reduce the amount of AlN based secondary phases (polypoids) which could occur in the final product by reducing the particle size before adding the AlN powder to the mixture and to reduce the decrease in transparency due to the variety of phases. The particle size distribution of the AlN powders before and after milling was characterized by laser diffraction spectroscopy. Microstructure and phase characterization of spark plasma sintered (SPS) alpha-SiAlON ceramics were performed using scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques, respectively. The infrared (IR) transmission of the ceramics was investigated using FT-IR in the 3000-7000 cm(-1) wavenumber range. The results showed that the particle size of the AlN powder was effective on the morphology, phase composition and optical properties of the alpha-SiAlON ceramics.