Silicon Nitride-Bonded SiC (SNBSC)

Silicon nitride bonded silicon carbide (SNBSC) is a porous low-cost SiC ceramic, typically 15% porous, but in its most high-tech manifestation, silicon aluminium oxynitride SiC (SIALON-SiC), porosity can be reduced to near zero. The invention of SNBSC in 1948 sparked a slow revolution in the SiC refractories technology realm, owing to the low cost and simplicity of the SNBSC manufacturing process, and the huge leap forward it represented over glass-bonded SiC (GBSC) refractories technology. The SNBSC revolution gained momentum in the 1970s after the lapse of key patents, and became a widely used technology globally in the refractories industry, particularly in the iron and steel and aluminium smelting industries. The evolution of SNBSC ultimately led to the second major breakthrough, in the invention of SIALON-SiC in the 1980s. In this highly evolved form (patented in the 1990s), SIALON-SiC is beginning to spark a revolution in the SiC refractories and wear-resistant ceramics realms. This chapter outlines in detail the following issues. The positioning of SNBSC in terms of properties, cost, and manufacturing complexity among the various SiC ceramic types in industrial usage (RSSC, DSSC, HPSC, GBSC, GBSC-CMC, SiC–SiC and SiC single-crystal technology). The evolution and science underlying the SNBSC technology. Contemporary manufacturing principles for SNBSC. The key industrial applications for SNBSC. The current cutting edge in SNBSC for refractories and for industrial wear resistance applications. In summary, SNBSC, and especially its more recent evolution, SIALON-SiC, while generally considered lower tech than all other industrial SiC types, other than GBSC, are the most important type of SiC in terms of market volume globally, and they are continuing to grow in importance and sophistication as time goes by.