Multi-coloured mosaic decoration of glasses - contg alkali metal oxides with compsns contg vanadium, silver and copper

摘要

Glasses and ceramics contg. alkali metal oxides (generally 2-25 wt % as oxide) are coated with a compsn. contg. Ag and/or Cu cpds. and a cpd. of Vanadium which on thermal decompsn. will give V2O5 so that the density of Ag and/or Cu cpds. is 0.2-2 pref. 0.5-1.0 mg/cm2 and that of the vanadium cpd. is 0.4-2.5 pref. 0.8-2.2 mg/cm2. The wt. ratio of the total Ag and/or cu cpds. to the vanadium cpd. should be 0.3-1.5. The coating is applied as a powder, paste, liq. or spray and may contain a dispersing agent e.g. Al2O3 TiO2, a filler e.g. methylcellulose and a diluent such as water. Suitable Ag and Cu cpds. are AgNO3 AgCl, Ag2SO4, Ag2CrO4 Cu(NO3)2. 2H2O CuCl, CuCl2 and CuSO4. The vanadium cpd. may be V2O5 or pref. NH4VO3. The coated glass is fired, usually between 580 degrees and 1000 degrees C until the correct colour has been obtained. Colouring and crystallisation of vitreous ceramic can be carried out simultaneously if the thermal treatment is sufficient for crystallisation (700-1000 degrees C for at least 2 min). The V2O5 and Ag and/or Cu cpds. form a melt which does not wet the glass well and even uniformly applied coatings form irregular droplets giving non-uniform distributions of Ag and Cu atoms or ions. At lower temps. the colours are yellow or red, at higher temps. blue and green. Attractive, easily produced mosaic finish in various colours is obtd.