Patent ID: 6531423
Filing Date: 2003-03-11
Classification: C04B

Abstract:
A polycrystalline SiC shaped body comprising 96% by weight to 99.5% by weight of a hard-material phase; 0 to 0.1% by weight free carbon; remainder a partially crystalline binder phase; the hard-material phase comprising SiC and a Siâ€”Câ€”Alâ€”Oâ€”N mixed crystal, containing 0.2 to 1.5% by weight dissolved aluminum, 0.1 to 0.5% by weight dissolved nitrogen, 0.01 to 0.2% by weight dissolved oxygen,the hard material phase comprising globular grains with a mean grain size of <4 &mgr;m, at least three grains enclosing a triple junction the globular grains having a structure comprising a core and a shell surrounding the core, the core comprising SiC and the shell comprising a Siâ€”Câ€”Alâ€”Oâ€”N mixed crystal, the mixed crystal having an Al/N atomic ratio of 1.0:1.0 to 2.0:1.0, and the partially crystalline binder phase comprising crystalline and amorphous phases of the rare earth metal â€”Alâ€”Siâ€”O quaternary system, the amorphous phase being present in the form of a grain boundary film which surrounds the globular grains, and the crystalline phase being present in form of accumulations at the triple junctions comprising rare earth aluminate.