Abstract: Process to manufacture glass or glass ceramic articles with a graphite insert encapsulated therein, characterized by the fact that said encapsulation is made in the presence of one or several gas getter metals chosen among aluminum, chromium, niobium, tantalum, titanium and zirconium.

Abstract: This invention relates to the preparation of glass-ceramic articles in which potassium fluorrichterite and/or a related fluormica constitutes the predominant crystal phase(s). The precursor glasses can be crystallized in situ very rapidly and exhibit very little thermal deformation during the crystallization heat treatment. The base glasses are essentially free of Li.sub.2 O and consist essentially, expressed in terms of weight percent on the oxide basis, of:______________________________________ SiO.sub.2 61-70 Na.sub.2 O 0.5-3 BaO 0-3.5 Al.sub.2 O.sub.3 2.75-7 K.sub.2 O 2.5-5.5 P.sub.2 O.sub.5 0-2.5 MgO 11-16 Na.sub.2 O + K.sub.2 O <6.8 CaO 4.75-9 F 2-3.

Abstract: The present invention is primarily concerned with the production of transparent glass-ceramic articles especially suitable for use as cooking utensils nucleated with up to 6% TiO.sub.2 and containing up to 0.25% Fe.sub.2 O.sub.3 and, perhaps, up to 0.1% MnO.sub.2, which exhibits a light brown tint that the human eye perceives essentially constant when the dominant wavelength is held between 577-581 nm, purity between 8-15%, and the transmission factor between about 65-80. The desired tint is obtained by including 0.0025-0.02% CoO+Cr.sub.2 O.sub.3, consisting of 0.001-0.01% CoO and 0.001-0.01% Cr.sub.2 O.sub.3, in the base composition of the glass-ceramic.