Abstract: A hot forming unit or debiteuse for plate glass production, with a noble metal box or frame encompassed by and contained in a highly heat-resistant ceramic frame and having a drawing slot matched to a cross section of a plate glass sheet to be produced. The dimensional integrity of the drawing slot of the noble metal frame is assured because the ceramic frame is constructed of longitudinal components and lateral components, where the longitudinal components of the ceramic frame and the longitudinal legs of the noble metal box rest against one another and are held so that they can still move axially against each other in a limited fashion. The longitudinal legs of the noble metal box are held in a stretched position by tension springs.

Abstract: A magnetic disc substrate is provided, which includes a magnetic disc substrate body made of glass and is characterized in that a metal element capable of absorbing light is present in at least a surface portion of the magnetic disc substrate body, and a texture is formed on a surface of the magnetic disc substrate body. Ions of the metal element are dispersed in the surface portion of the magnetic disc substrate, or the metal element is contained in a composition of the glass constituting the magnetic disc substrate in the form of an oxide. The glass is preferably a crystallized glass a Li.sub.2 O--Al.sub.2 O.sub.3 --SiO.sub.2 based crystallized glass, which particularly preferably contains 65 to 85 wt % of SiO.sub.2, 8 to 15 wt % of Li.sub.2 O, 2 to 8 wt % of Al.sub.2 O.sub.3, 1 to 5 wt % of P.sub.2 O.sub.5 and 1 to 10 wt % of ZrO.sub.2 and has lithium disilicate (Li.sub.2 O.multidot.2SiO.sub.2) as a main crystalline phase.

Abstract: In order to provide a crystallized glass which can be shaped by the redraw forming and a method of manufacturing a crystallized glass article by the redraw forming, the crystallized glass contains precipitated crystals with a maximum grain size not greater than 5 .mu.m and a glass phase at a ratio of 10 to 85 vol %, and has a softening point lower than a melting point of a predominant precipitated crystal, and a property such that crystallization does not progress even when heated at a temperature higher than the softening point. In order to manufacture the crystallized glass article formed by the redrawing, the above-described crystallized glass is preformed and then subjected to the drawing while being heated to a temperature higher than the softening point.

Abstract: A glass-ceramic substrate for a magnetic head has as its predominant crystal phase a mixed crystal of lithium disilicate (Li.sub.2 O.2SiO.sub.2) and either or both of .alpha.-quartz (.alpha.-SiO.sub.2) and .alpha.-cristobalite (.alpha.-SiO.sub.2), the .alpha.-quartz has a globular grain structure each globular crystral grain being made of aggregated particles and having a grain diameter within a range from 0.1 .mu.m to 3.0 .mu.m, the .alpha.-cristobalite has a globular grain structure each globular grain having a grain diamter within a range from 0.1 .mu.m to 1.0 .mu.m, and surface roughness (Ra) of the glass-ceramic substrate after polishing is within a range from 5 .ANG. to 50 .ANG..

Abstract: The invention relates to a method of making glass-ceramic plates which are bent at a radius of curvature especially suitable in the manufacture of cooking plates.

Abstract: Beta-spodumene bodies and method of preparing the bodies that involves providing a uniform plastic batch of inorganic raw materials, organic binder, and vehicle, wherein the inorganic raw materials are composed of, in percent by weight, about 75% to 95% minerals, and about 5% to 25% glass. The batch is formed into a green body that is fired to produce a body composed substantially of beta-spodumene, and having a thermal expansion coefficient of <10.times.10.sup.-7 /.degree.C.(0-800.degree. C.), and a strength of .gtoreq.4 Ksi.

Abstract: A method for detecting a defect in a glass-ceramic for magnetic disks includes steps of forming a colored glass-ceramic having Munsell value within the range of 0 to 7 in the CIE color system by subjecting to heat treatment a base glass comprising in weight percent:______________________________________ SiO.sub.2 65-83% Li.sub.2 O 8-13% K.sub.2 O 0-7% MgO + ZnO + PbO 0.5-5.5% in which MgO 0.5-5.5% ZnO 0-5% PbO 0-5% P.sub.2 O.sub.5 1-4% Al.sub.2 O.sub.3 0-7% As.sub.2 O.sub.3 + Sb.sub.2 O.sub.3 0-2% a coloring agent of at least one ingredient 0.5-5% selected from the group consisting of metal oxides of V, Cu, Mn, Cr, Co, Mo, Ni, Fe, Te, Ce, Pr, Nd and Er ______________________________________and checking the glass-ceramic visually or by means of an automatic checking device for detecting a defect in the glass-ceramic.

Abstract: A magnetic disk substrate is made of a glass-ceramic having crystal phases of lithium disilicate (Li.sub.2 O.2SiO.sub.2) and alpha-quartz (SiO.sub.2). The crystal phase of alpha-quartz is formed of grown crystal grains each having a globular grain structure made of aggregated particles. Each globular grain has a size within a range from 0.3 .mu.m to 3 .mu.m. Surface roughness (Ra) of a polished surface of the magnetic disk substrate is within a range from 15 .ANG. to 50 .ANG. which is an optimum range of surface roughness for the magnetic disk.

Abstract: Extruded low-expansion ceramic honeycombs comprising beta-spodumene solid solution as the principal crystal phase and with less than 7 weight percent of included mullite are produced by compounding an extrusion batch comprising a lithium aluminosilicate glass powder and a clay additive, extruding a green honeycomb body from the batch, and drying and firing the green extruded cellular honeycomb to crystallize the glass and clay into a low-expansion spodumene ceramic honeycomb body.

Abstract: A positive containment threshold for use in an apparatus for manufacturing flat glass includes a metal base with a combination of vertically disposed members for connection to a bottom casing of a glass forming chamber. Disposed adjacent a vertical member which serves as an end wall casing member in the combination is at least one refractory threshold block which provides a smooth glass contact surface over which molten glass may be delivered onto a pool of molten metal contained within the bottom portion of an enclosed forming chamber. This threshold in combination with the casing surrounding the bottom portion of an enclosed forming chamber provides an impervious barrier to prevent the inadvertent loss of molten metal from the container in the event of refractory failure.