| WHEN amorphous silica is heated to
temperatures above 900°C nucleii of cristobalite
are formed, which subsequently grow
with increasing heating time.1 The degree of
order in the structure of cristobalite crystals
formed, however, varied a great deal, depending
on the condition under which it is formed2•
Quartz is also believed to be transformed to an
intermediate amorphous state, from which cristobalite
is formed.4 The object of the present
study was to examine the possibility of transforming
mixture of silica and some minor additions
to glass before crystals of cristobalite could
grow. The minor additions tried were Ti02,
Al20 3, AIF3 and B20 3, which are known to
lower the melting temperatures of silica without
having any significant effect on its favourable
thermal properties. |
