FABRICATION OF FUNCTIONALLY GRADED SiAlON CERAMICS BY TAPE CASTING CASTING

Functionally graded SiAlON ceramics (FG-SiAlONs) were prepared by tape casting and lamination. Non-aqueous SiAlON slurries with five different alpha to beta-SiAlON ratios (85 alpha:15 beta, 70 alpha:30 beta, 55 alpha :45 beta, 40 alpha:60 beta, and 25 alpha:75 beta) were prepared by a 66 methyl ethyl ketone/34 ethanol (vol%) mixture. Phase and microstructure analyses incorporated with hardness measurements clearly show that the FG-SiAlONs, prepared by tape casting, exhibit a continuous and gradual change in composition and hardness. Thus, the tape casting approach is a viable method to produce FG-SiAlONs with a precisely controlled composition, and subsequently properties, as a function of position. 19 refs.