vitrifiable enamels and glazes for colorees glacures transparent or opaque

摘要

Compsns. for forming vitreous, transparent, coloured or opaque glazes on porous or compact ceramic articles, and having a mean linear thermal expansion coefft. 8.0 x 10-6/degrees C (20-400 degrees C) and 8.5 x 10-6/degrees C (20 degrees C to the glass transition pt.) comprise 65-75% SiO2 0-6% Al2O3 4-12% B2O3 and 8-12% PbO, 12-16% alkali metal oxides and 0-4%, alkaline earth oxides and/or fluorides SiO2 + Al2o3 being 67-75%, and the balance being 20-30% flux comprising 0-10% of various coloured oxides, soluble in the compsn., chosen pref. from CaO, CuO, NiO and Fe2O3, and 0-5 mol% of one or more of ZrO2, TiO2, SnO2, Nb2O5 and CeO2, 0-10 mole% coloured pigments, pref. spiral and 0-10 mol% flux. Glazes have an improved chemical stability, reduced tendency to release head, and are particularly suitable for glazing porous and impermeable ceramics, glass-ceramics and quartz or porous sintered articles leased on glass and scrap silicate, esp. having linear expansion coefft. 8.0 x 10-6/degrees C. The firing temp. of the glaze compsn. is 900 degrees C.