The invention relates to a process for the preparation of a glass-ceramic blank for dental purposes with lithium silicate as crystal phase, in which lithium silicate blanks that are no longer required and in particular residues thereof are used as starting material and which allows the production of a homogeneous starting glass within a short time.

The invention relates to glass-ceramics based on the lithium silicate system which can be mechanically machined easily in an intermediate step of crystallization and, after complete crystallisation, represent a very strong, highly-translucent and chemically-stable glass-ceramic Likewise, the invention relates to a method for the production of these glass-ceramics. The glass-ceramics according to the invention are used as dental material.

The invention relates to glass-ceramics based on the lithium silicate system which can be mechanically machined easily in an intermediate step of crystallization and, after complete crystallisation, represent a very strong, highly-translucent and chemically-stable glass-ceramic Likewise, the invention relates to a method for the production of these glass-ceramics. The glass-ceramics according to the invention are used as dental material.

A lithium aluminum silicate glass ceramic, which, apart from unavoidable impurities, is As2O3-free and Sb2O3-free. The lithium aluminum silicate glass ceramic has keatite as primary crystal phase and a keatite peak temperature TP of the keatite solid solution formation in the range of 980° C. to 1090° C., and the keatite peak temperature TP is determined by dynamic differential calorimetry (DSC) in accordance with DIN 51007:2019-04 at a heating rate of 5 K/min. A ceramization method is also described.

A lithium aluminum silicate glass ceramic, which, apart from unavoidable impurities, is As2O3-free and Sb2O3-free. The lithium aluminum silicate glass ceramic has keatite as primary crystal phase and a keatite peak temperature TP of the keatite solid solution formation in the range of 980° C. to 1090° C., and the keatite peak temperature TP is determined by dynamic differential calorimetry (DSC) in accordance with DIN 51007:2019-04 at a heating rate of 5 K/min. A ceramization method is also described.

Disclosed in the present invention is a multi-crystal nucleus transparent glass-ceramic and a preparation method therefor, said preparation method comprising the following steps: during glass production, adding a plurality of types of nucleation agents, and after processing, acquiring a mother glass having certain outer dimensions; and placing the mother glass obtained in S2 under a temperature of T1 and heating for 1 h-6 h to perform annealing treatment, after the annealing treatment is complete, placing under a temperature of T2 and heating 1 h-6 h to perform nucleation treatment, and after nucleation treatment is complete, placing under a temperature of T3 and heating 0-3 h to perform crystallization treatment. T1<T2. The present invention produces a glass-ceramic containing multiple types of crystal nuclei and having crystal phases of lithium disilicate and petalite. The multiple crystal nuclei reduces the nucleation and crystallization energies required for devitrification, thus being able to reduce thermal treatment temperature and time, and adjust the ratio of crystals. The glass-ceramic prepared by means of the present preparation method features an increased damage resistance, good fracture toughness, and a broad application range.

Disclosed in the present invention is a multi-crystal nucleus transparent glass-ceramic and a preparation method therefor, said preparation method comprising the following steps: during glass production, adding a plurality of types of nucleation agents, and after processing, acquiring a mother glass having certain outer dimensions; and placing the mother glass obtained in S2 under a temperature of T1 and heating for 1 h-6 h to perform annealing treatment, after the annealing treatment is complete, placing under a temperature of T2 and heating 1 h-6 h to perform nucleation treatment, and after nucleation treatment is complete, placing under a temperature of T3 and heating 0-3 h to perform crystallization treatment. T1<T2. The present invention produces a glass-ceramic containing multiple types of crystal nuclei and having crystal phases of lithium disilicate and petalite. The multiple crystal nuclei reduces the nucleation and crystallization energies required for devitrification, thus being able to reduce thermal treatment temperature and time, and adjust the ratio of crystals. The glass-ceramic prepared by means of the present preparation method features an increased damage resistance, good fracture toughness, and a broad application range.

The present invention relates to a crystallized glass including a crystalline phase consisting of Ba—Si—O, in which the crystallized glass includes Li, and crystallinity of Li-based crystals contained in the crystalline phase is 20% or lower as represented by weight %, a high-frequency substrate including the crystallized glass, and a manufacturing method for a crystallized glass including a crystalline phase consisting of Ba—Si—O, the method including: obtaining an amorphous glass by melt-shaping a material containing BaO and SiO.sub.2; and crystallizing the amorphous glass by holding the amorphous glass at a treatment temperature of 600° C. or higher and lower than 1,000° C.

The present invention relates to a crystallized glass including a crystalline phase consisting of Ba—Si—O, in which the crystallized glass includes Li, and crystallinity of Li-based crystals contained in the crystalline phase is 20% or lower as represented by weight %, a high-frequency substrate including the crystallized glass, and a manufacturing method for a crystallized glass including a crystalline phase consisting of Ba—Si—O, the method including: obtaining an amorphous glass by melt-shaping a material containing BaO and SiO.sub.2; and crystallizing the amorphous glass by holding the amorphous glass at a treatment temperature of 600° C. or higher and lower than 1,000° C.

Provided is a dental bulk block made from a glass-ceramic material having a crystalline phase embedded in an amorphous glass matrix. The crystalline phase includes eucryptite and at least one lithium silicate-based crystalline phase selected from the group consisting of lithium metasilicate and lithium disilicate. The dental bulk block is a functionally graded material having a crystalline size gradient with respect to a depth thereof and having no interface at a point of change in main crystalline size gradient value. The bulk block that is heat-treated at 820° C. for 40 minutes exhibits a characteristic peak of a spodumene crystalline phase in an X-ray diffraction analysis result graph unlike the bulk block that is heat-treated at 820° C. for 2 minutes.