the microstructure consists of elongated crystals that interlock into micro-rods.
Silicon nitride ceramics has excellent wear resistance,outstanding fracture toughness and good thermal stability.
It is these features that make it suitable for appplications as following:Ligh-speed bearings,high precision bearings,
Tools for heavy-type ceramic forming,automotive components subject to high stress.and the good thermal shock 
Resistance and high temperature resistance is exploited in welding processes.