Abstract: The present invention relates to a process and apparatus useful therein for steam hydrating alkali silicate glass materials and subsequently extruding the hydrated material. There need be no moving parts in the hydration apparatus since the process can utilize the pressure of steam to both hydrate the glass and extrude it from the hydration chamber. The process permits the formation of solid extrusions or foam extrusions.

Abstract: This invention is concerned with the production of composite articles comprising a glass or glass-ceramic matrix containing long fibrous single crystals of rutile (TiO.sub.2) of very high aspect ratios grown in situ. The glass articles are formed via the heat treatment of a molten batch consisting essentially, by weight on the oxide basis, of about 45-65% B.sub.2 O.sub.3, 5-30% Al.sub.2 O.sub.3, 5-30% TiO.sub.2, and 3-30% alkaline earth metal oxides and can exhibit greatly improved mechanical strength and toughness when compared with the original, or fiber-free, glass. The glass-ceramic articles are formed by heat treating the fiber-containing glass in a particular manner to cause the development of fine-grained crystals in situ, resulting in a highly-crystalline article containing long fibrous single crystals of rutile exhibiting verh high aspect ratios.

Abstract: This invention is concerned with glass-ceramic articles having compositions within a very narrowly-delimited area of the MgO-Al.sub.2 O.sub.3 -B.sub.2 O.sub.3 -SiO.sub.2 field and having alpha-quartz and sapphirine as the principal crystal phases, resulting from nucleation through a combination of TiO.sub.2 and ZrO.sub.2. Upon contacting such articles with lithium ions at an elevated temperature, said lithium ions will replace magnesium ions on a two Li.sup.+-for-one Mg.sup..sup.+2 basis within the crystal structures, thereby providing a unitary glass-ceramic article having an integral surface layer wherein the principal crystal phase is a lithium-stuffed beta-quartz solid solution. That transformation of crystal phases results in compressive stresses being set up within the surface layer as the articles are cooled.