The present disclosure provides a method for fabrication of a glass preform. The method includes production of soot particles in a combustion chamber using a precursor material. The heating of the precursor material produces the soot particles along with one or more impurities. In addition, the method includes agglomeration of the soot particles. Further, the method includes separation of the soot particles from the one or more impurities. Also, the separation of the soot particles is performed in a cyclone separator. Furthermore, the method includes collection of the soot particles. Also, the soot particles are compacted with facilitation of a preform compaction chamber. Also, the compacted preform is sintered with facilitation of a sintering furnace. The compaction of the soot particles followed by sintering results in formation of the glass preform.

Ceramics and glass-ceramics have low and/or negative coefficients of thermal expansion. Crystalline phases of the formula AM.sub.2Si.sub.2-yGe.sub.yO.sub.7 (A=Sr and Ba and M=Zn, Mg, Ni, Co, Fe, Cu, Mn, with Sr, Ba and Zn necessarily having to be present) can be produced by conventional ceramic processes or by crystallization from glasses. The compositions form solid solutions, where the elements indicated as component M can be replaced by one another in virtually any concentration but the concentration of Zn must always be at least 50% of the sum of all components indicated under M. The stoichiometry of these silicates and also their structure can differ to a greater or lesser extent.

Disclosed are a glass ceramic material, a preparation method thereof, and a denture. The glass ceramic material includes the following components by mass percentage: 58% to 72% of SiO.sub.2, 0% to 4% of Al.sub.2O.sub.3, 0% to 5% of Na.sub.2O, 3% to 8% of K.sub.2O, 8% to 17% of Li.sub.2O, 2.5% to 5% of P.sub.2O.sub.5, 0% to 2% of MgO, 0% to 2.5% of B.sub.2O.sub.3, 0% to 5% of ZnO and 0% to 3% of ZrO.sub.2. In the present application, by optimizing the composition and ratio of the glass ceramic material, and combining with a matching process system, it is possible to control the formation of lithium disilicate while the crystallinity of lithium metasilicate glass ceramic can be improved without an introduction of a high ratio of zirconia content, thereby improving the grinding performance of the glass ceramic. The present application is applicable to the field of material technology.

The invention discloses a method for preparing lead smelting slag glass-ceramics based on the oxidation of silicon-rich silicon smelting slag and composition adjustment, and belongs to the technical field of resource utilization of smelting slag rich in monatomic silicon. The method comprises the steps: mixing the silicon slag rich in monatomic silicon with an oxidant, a fluxing agent and a clarifying agent according to a formula ratio, ball-milling and screening to obtain a tempering raw material with uniform size, and performing high-temperature oxidation melting on the tempering raw material to form an oxidation-state molten tempering material; and carrying out further mixed melting on the molten tempering material and hot lead slag, carrying out water quenching to obtain basic glass, and carrying out heat treatment system on the obtained basic glass to form the glass ceramics. According to the method, the smelting slag rich in monatomic silicon is subjected to oxidation tempering and mixed melting with the hot lead slag to prepare the basic glass, and the glass ceramics are obtained by regulating and controlling the heat treatment system of the basic glass. The method is simple in technological process, high in production efficiency and low in cost, achieves the collaborative high-value conversion target of the silicon-rich silicon slag and the lead slag, and is easy to industrially popularize and apply.

Glass ceramics having SiO.sub.2 as main crystal phase and precursors thereof are described which are characterized by very good mechanical and optical properties and in particular can be used as restoration material in dentistry.

A method of making a glass-ceramic article includes synthesizing a feedstock gel that includes a base oxide network comprising Na.sub.2O, CaO, and SiO.sub.2, in which a molar ratio of Na.sub.2O:CaO:SiO.sub.2 in the gel is 1:2:3, and then converting the feedstock gel into a glass-ceramic article such as a container or a partially-formed container. The conversion of the feedstock gel into a glass-ceramic container may be performed at a temperature that does not exceed 900 C. and may include the steps of pressing the feedstock gel into a compressed solid green-body, sintering the green-body into a solid monolithic body of a glass-ceramic material, deforming the solid monolithic glass-ceramic body into a glass-ceramic preform, and cooling the preform. A glass-ceramic article having a glass-ceramic material that has a molar ratio of Na.sub.2O:CaO:SiO.sub.2 that is 1:2:3 is also disclosed.

A method of making a glass-ceramic article includes synthesizing a feedstock gel that includes a base oxide network comprising Na.sub.2O, CaO, and SiO.sub.2, in which a molar ratio of Na.sub.2O:CaO:SiO.sub.2 in the gel is 1:2:3, and then converting the feedstock gel into a glass-ceramic article such as a container or a partially-formed container. The conversion of the feedstock gel into a glass-ceramic container may be performed at a temperature that does not exceed 900 C. and may include the steps of pressing the feedstock gel into a compressed solid green-body, sintering the green-body into a solid monolithic body of a glass-ceramic material, deforming the solid monolithic glass-ceramic body into a glass-ceramic preform, and cooling the preform. A glass-ceramic article having a glass-ceramic material that has a molar ratio of Na.sub.2O:CaO:SiO.sub.2 that is 1:2:3 is also disclosed.

A quartz glass provides an opaque quartz glass having high light-shielding property, excellent mechanical strength and excellent cleaning resistance against hydrofluoric acid. By setting the maximum width of the amorphous bubbles existing in the opaque quartz glass to an average of 3 to 15 ?m and the density to 2.15 g/cm.sup.3 or more, the mechanical strength after baking and the cleaning resistance by hydrofluoric acid are improved. The opaque quartz glass has a whiteness at a thickness of 10 mm of 75 to 90%, the reflectance of light with a wavelength of 0.24 to 2.6 ?m at a thickness of 4 mm is 60 to 85%, and the bending strength after baking is 95 MPa. In addition, a foaming agent may be mixed in the opaque quartz glass. An opaque quartz glass having cleaning resistance against acid can be obtained.

A multiple mold (42) for production of at least two glass-ceramic blanks. The glass-ceramic blanks are for dental purposes and are produced from at least two powder blanks by hot pressing. The multiple mold (42) includes a frame (48) that defines at least sections of a receiving volume (50) for the at least two powder blanks. Additionally provided is a separating element (52) which is disposed within the receiving volume (50) and divides the receiving volume (50) into at least two subvolumes, each of which is designed to accommodate one of the at least two powder blanks. Also described are the use of the multiple mold (42) for production of a glass-ceramic blank for dental purposes, a compression apparatus and a continuous system for production of glass-ceramic blanks for dental purposes.

Glass ceramics having SiO.sub.2 as main crystal phase and precursors thereof are described which are characterized by very good mechanical and optical properties and in particular can be used as restoration material in dentistry.