| The glass composition, MgO 11.5%, ACO;; 21.4%, SiOc 60.5% and TiOc 6.4%
(by weight), was crystaltised at different f.emj;eratures ranging from 825 to 1225°
under controlled conditions. Th,e crystal pha.1es were detected by X-ray method and
the modulus o:f rupture, thermal expansion and d,ensity of the crystallised samples
were measured. All the three propertzes increased to a maximum with increasing
crystalli~ation temperature. HiJ;her density and the11mal expansion of the crystal phases
haz·e been shown to produce compresJiuf stress on ,t;lass and, as a result, the stnength
increases to a maximum of 5,500 kg I cm2
, compared to 1,700 k,t; I cm2 for uncrystal!lised
glass. The relations between stress, th,ermal exp•ansion and density have been
discussed quantitatively. |
