Fine-grained canasite glass-ceramics for making memory storage devices

摘要

This invention relates to the production of glass-ceramic articles, with particular reference to substrates for rigid information disks to be used in magnetic memory storage devices. The glass-ceramic articles are highly crystalline, very fine-grained, and are prepared by heat treating precursor glass articles consisting essentially, expressed in terms of weight percent on the oxide basis, of SiO₂50-65K₂O6-12CaO18-25Al₂O₃0-2.5Na₂O6-11F5-9 for at least two hours at a temperature within the range of about 625°-700°C. Canasite crystals constitute essentially the sole crystal phase, these crystals averaging no more than about 1µm in length and no more than abort 0.5µm in width.