Formation of Silicon Nitride Whiskers on a Ferro-Silicon Alloy at Room Temperature

AFTER approximately ten years of operation, a calcium carbide furnace at Odda Smelteverk A/S, Norway, was temporarily stopped. At the bottom of the furnace a phase containing a ferro-silicon alloy was found. A sample taken from this bottom phase was kept in contact with air at room temperature. After a few weeks, formation of greyish-brown whiskers on the surface of the sample was observed.