Abstract: The present invention is directed to the production of glass-ceramic coatings capable of being fired repeatedly to temperatures in excess of 950.degree. C. without thermal deformation and being especially suitable for application to titanium-stabilized stainless steels. The coatings are highly crystalline, substantially free from alkali metal oxides, and consist essentially, by weight, of:______________________________________ MgO 5-35 CaO 0-35 ZnO 0-25 CaO + ZnO 10-35 Al.sub.2 O.sub.3 0-10 B.sub.2 O.sub.3 0-25 P.sub.2 O.sub.5 0-10 B.sub.2 O.sub.3 + P.sub.2 O.sub.5 4-25 SiO.sub.

Abstract: This invention is directed to means for producing strengthened, transparent glass-ceramic, partially body-crystallized, and surface-crystallized glass articles wherein beta-quartz solid solution constitutes the predominant crystal phase. The inventive method comprises subjecting a glass article consisting essentially, expressed in terms of weight percent, of about 2.5-6% Li.sub.2 O, 0.5-5% RO, wherein RO consists of ZnO and the alkaline earth metal oxides BaO, CaO, MgO, and SrO, 16-25% Al.sub.2 O.sub.3, 64-73% SiO.sub.2, and 3.0-6% RO.sub.2, wherein RO.sub.2 consists of 0-6% TiO.sub.2 and 0-3.5% ZrO.sub.2, to vapors of SO.sub.2 and thereafter heat treating the glass article to cause crystallization in situ thereof.