JOINING SIALON CERAMICS USING COMPOSITE BETA-SIALON GLASS ADHESIVES

Commercial beta-SiAlON ceramics were joined using mixed Si3N4, Y2O3, Al2O3, and SiO2 powders. At a joining temperature of 1600-degrees-C and a hold time in excess of 10 min, the adhesive was converted to an approximate 60:40 vol% composite of beta-SiAlON-glass-ceramic. The grain size of the acicular beta-SiAlON grains precipitated in the joint (submicrometer diameter, average aspect ratio of 10) was significantly smaller than those in the adherend ceramic (1-5-mu-m diameter). Intergrowth of beta-SiAlON grains at the joint interface resulted in high bond strengths. The chemistry and microstructure of the ceramic adhesives used are described.