Study of Lithium Aluminum Silicate Glass Crystallization in the Range 825 – 875°C

Abstract

Results are provided for a study of lithium aluminium silicate glass crystallization in the range 825 -875°C.Keywords: glass ceramic, crystallization, lithium aluminium silicate glass, x-ray-phase analysis (XPA).Ceramic technology is used currently in ONPP Tekhnologiya for preparing objects of glass ceramics OTM-357 and OTM-357-O (main phase b-spodumene) [1 -4]. According to this technology objects are molded from amorphous and previously crystallized lithium aluminium silicate glass respectively. Use of previously crystallized lithium aluminium silicate glass makes it possible to reduce heat treatment duration from 70 to 24 -30 h. Since prior crystallization of lithium aluminium silicate glass is performed at 1170 -1250°C for 4 -8 h this requires additional use of high-temperature firing furnaces and increases firing time for a single object up to 10 h.Results are provided in [5] for a study of the possibility of reducing prior crystallization for an original lithium aluminium silicate glass and its use for manufacturing objects for radio engineering purposes. In addition, the possibility of demonstrated of using material previously crystallized at 850 -900°C for preparing lithium aluminium silicate glass workpieces, which provides a reduction in the level of glass heat treatment temperature from 1180 -1250 to 850 -900°C. As a result of this a possibility develops of not performing heat treatment within high-temperature firing furnaces, but in low-temperature (up to 1000°C) furnaces with reduced heat treatment duration. Results obtained [5] point to a requirement for more profound study in the area of original glass crystallization in the range 850 -900°C.Crystallization processes for lithium aluminium silicate glass have been studied in a DRON-6 x-ray diffractometer by means of a PDWIN program and in an EVO-40 XVP scanning electron microscope (SEM). Standard methods, instruments, and units were used in order to determine ceramic Fig. 1. XPA results for specimens heat treated at 825 (a), 850 (b ) and 875°C (c): 1 ) b-eucryptite; 2 ) alumotitanate.