“…The studied material, SN 88, is a commercial gas-pressuresintered silicon nitride produced by NGK Insulators, Ltd., Nagoya, Japan, for the hot stage components of ceramic gas turbines. This material represents a generation of SiC nano-composite silicon nitride ceramics from the beginning of the 1990s, which was extensively studied by Luecke et al (1995), Lofaj et al (1997aLofaj et al ( , 1997bLofaj et al ( , 1999aLofaj et al ( , 2000Lofaj et al ( , 2003aLofaj et al ( , 2003b, Luecke and Wiederhorn (1999), Lofaj (2000), Wiederhorn (2000) and Yoon et al (2000). Its microstructure consists of large -silicon nitride grains (up to 50-80 m long, diameter 5-10 m) embedded in a fine -Si 3 N 4 matrix.…”