Functionally graded SiAlON ceramics

Abstract

Functionally graded SiAlON ceramics were developed by three different methods to improve the mechanical properties of SiAlONs; powder bed, rapid cooling and laminating. beta-SiAlON compacts were embedded in two different homogeneously mixed powder bed compositions, alpha-SiAlON (100 wt.%) and AlN: BN (50:50 wt.%). The affect of powder bed composition and pressure on the formation of alpha-SiAlON on the compact surface was investigated. Rapid cooling to retain transformed alpha-SiAlON was also another method under investigation. Lamination is another method for production of functionally graded materials. For this purpose laminar type of functionally graded SiAlON ceramics with two layers, which have different compositions, were produced. Transition zone obtained in different methods were examined by phase characterization technique, microstructural investigations and hardness measurements. The results showed that laminar type is the most effective method for FGM SiAlON ceramics production