Made
from chromite sand and additives, chrome nozzle filler sand has the advantages
of high specific gravity, good fluidity, high melting point, not excessively
sintered, etc. When the added chromite
sand is over 60%, chromite will be in continuous distribution, which
can help forming continuous sintered layers.
Under
high temperature, the FeO in chromite
sand will react and dehydrate, producing quadratic spinel, then the volume
of sintered layer will change and crack, when the slide gate plate is opened,
the unsintered nozzle filler sand in the lower part of nozzle will flow out
very fast, the cracks in the sintered layer will expand, due to the static
pressure of molten steel, the sintered layer will be totally broken. All the
above steps finally lead to automatic opening.