Stirrer (1) for stirring molten glass (16), whereby the stirrer (1) comprisesa shaft (2) having a tip (4) and having a central longitudinal axis (L), andone or more inner stirrer blades (5,6) which are attached to the shaft (2), andone or more outer stirrer blades (7,8) which are attached to the shaft (2), whereby the inner stirrer blades (5,6) are attached closer to the shaft (2) than the outer stirrer blades (7,8), whereby, when considering the stirrer in a cylindrical coordinate system (11), both the one or more inner stirrer blades (5,6) as well as the one or more outer stirrer blades (7,8) are disposed at an angle (?, ?) to the central longitudinal axis (L), whereby said angle (?, ?) is between 0? and 90? not including these values, and are disposed having a least a blade section with a normal vector (N, P, Q, R), on the side directed towards the tip (4), with an angular component (N.sub.A, P.sub.A, Q.sub.A, R.sub.A).

Methods, systems and apparatus for producing continuous basalt fibers, microfibers, and microspheres from high temperature melts are disclosed. A cold crucible induction furnace is used to super heat crushed basalt rock to form a melt. The melt is cooled prior to forming a fiber. The fiber produced from the superheated melt possesses superior properties not found with conventional basalt fibers produced in gas furnaces. In some implementations, the superheated melt is spun into continuous basalt fibers. In some implementations, the superheated melt is blown into microfibers and microspheres.

A glass article is designed at least in part in the form of a glass tube element including at least one shell which encloses at least one lumen. For at least one light transmission analysis of the glass article, a ratio of an average amplitude transmission factor and a specific amplitude transmission factor is greater than 1.00001.

A nanocomposite material that can withstand prolonged contact with molten glass and glass precursor melts may include a cermet substrate and a glass reaction material overlying the cermet substrate. The cermet substrate may include a refractory metal matrix and ceramic particles embedded in the refractory metal matrix, and the glass reaction material may be the reaction product of molten glass and the cermet substrate in an inert environment. The nanocomposite material can be used to construct any kind of structure, such as an impeller or a vessel liner, that may be exposed to molten glass or glass precursor melts.

Provided are a refractory article, an anti-redox coating composition, and a method of manufacturing the refractory article. The refractory article includes: a platinum(Pt)-based substrate; and a coating layer for preventing a redox reaction on a surface of the Pt-based substrate, wherein the coating layer for preventing a redox reaction includes on an oxide basis SiO2 in an amount of about 40 wt % to about 70 wt %, Al.sub.2O.sub.3 in an amount of about 20 wt % to about 52 wt %, B.sub.2O.sub.3 in an amount of about 3 wt % to about 6 wt %; and CaO in an amount of about 2.4 wt % to about 4.8 wt %.