GB743322A - Electrically-heated appliance, in particular a vessel for cooking, roasting or baking - Google Patents

Abstract

743,322. Enamels. WURTTEMBERGISCHE METALLWARENFABRIK. Sept. 22, 1950 [Oct. 4, 1949], No. 23332/50. Addition to 733,142. Drawings to Specification. Class 56 [Also in Group XI] The insulating properties of a vitreous enamel holding an electric heating resistance on a cooking vessel (see Group XI) are increased by largely replacing the constituents having increased ion conductivity at higher temperatures (such as alkali oxides) by constituents having a lower ion conductivity; and the enamel comprises by weight 20-40 per cent of silica, 40-65 per cent of lead oxide or barium oxide or a mixture of these, up to 6 per cent of alumina, up to 6 per cent of calcium oxide, up to 5 per cent of boric oxide and optionally up to 15 per cent of titanium oxide. The enamel contains up to 25 per cent of boric oxide, calcium oxide, aluminium oxide and titanium oxide, and may comprise 47.5 per cent of lead oxide, 4.2 per cent of calcium oxide, six per cent of alumina; 36.6 per.cent of silica, 4.6 per cent of boric oxide and 1.1 per cent of chromic oxide or other colouring oxide. Another example is 46.3 per cent of lead oxide. 13.25 per cent of barium oxide, 2.9 per cent of calcium oxide 0.53 per cent of alumina. 25 per cent of silica, 4.85 per cent of boric oxide, 6.66 per cent of titanium oxide and 0.51 ner cent of chronium oxide or other colouring oxide. Any compounds of the alkali oxides occur only as impurities. Usual oxidising agents, adhesion-promoting oxides, colour ing oxides and clouding agents -nay be present.