| 摘要 |
The invention relates to vitreous materials which can be converted by thermal treatment into glass-ceramics in which the essential crystalline phase possesses the crystallographic structure of tainiolite. The vitreous material is obtained by fusion of the mixture having the following composition, expressed in percentages by weight: SiO2: 45-70; MgF2: 12-20; MgO: 8-15; Li2O: 3-10; CaO: 0-10; M2O + M'O: 5-20; Al2O3 + ZrO2: 2-9; TiO2: 0-7; conventional dyes for glasses: 0-10; M2O representing one or more oxides chosen from K2O, Cs2O and Rb2O; M'O representing BaO and/or SrO; the quantity of M'O, expressed as the number of moles, being less than or equal to 50 % of the quantity of M2O; the weight percentage of Al2O3 being less than or equal to 3 and the weight percentage of ZrO2 being less than or equal to 6. The glass-ceramics obtained are especially useful for the production of dental prostheses. |
