A Study of the Devitrification of Glass
JSGT 1929 V13 T219-T229
On the basis of the investigation of a large number of samples of 70 different kinds of glasses subjected to heat treatment with the object of inducing crystallisation, the following conclusions may be made: (1) The presence of alumina (Al2O3) in the glass does not always tend to weaken the crystallising power. (2) An increased content of the alkalis in the glass, other conditions being equal, reduces the crystallising power. (3) Glasses containing a great number of components have a lower crystallising capability than the simpler glass. (4) The crystallising capacity of glasses decreases with the reduction of CaO content, and the content of CaO must not exceed 10%. (5) Glasses containing more than 11% of CaO, with an alkali content not exceeding 14% have a high crystallising capacity. (6) Glasses not containing any Al2O3 and having an equal percentage of CaO have the greatest crystallising capacity when the alkali content is lowest. (7) When MgO in the form of magnesite is substituted for CaO in standard glasses, it increases the crystallising capacity.
J. J. Kitaigorodsky
