Investigation of effects of starting composition and sintering conditions on transparent SiAlON ceramics

In this study, the effects of process parameters on the optical properties of SiAlON ceramics by providing control of these parameters is intended to improve the optical properties of SiAlON ceramics. In order to examine the effects of the type and amount of the sintering additives on the optical properties of transparent ?-SiAlON ceramics, three different cation (Dy+3, Y+3, La+3) and for each cation four different compositions ((m=2n=2), (m=n=1,2), (m=n=2), (m=n=1)) were selected and studied. The starting powders produced by high energy mechanical milling method and the conventional method were sintered by SPS and GPS. Samples were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) measurements. Nano-sized starting powders and Dy+3 as an additive use has been found to improve the optical properties of ?-SiAlON ceramics. Compared to the other sintering parameters temperature and pressure were observed to be more effective on density, microstructure, hence on the optical and mechanical properties. The results were discussed using the relationship between density, phase composition, microstructure and mechanical properties. Keywords: SiAlON, AlN-politypes, SPS, GPS, Optical properties, Microstructure