Method and apparatus for melting frits for inorganic oxidic surface coatings by electric resistance heating

US4246432A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Hans Rinkes · Neunburg vorm Wald, DE
• Werner Joseph · Cologne, DE

Key dates

• Filing date: Nov 13, 1978
• Grant date: Jan 20, 1981
• Expiry date: Nov 13, 1998

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C03B5/03
• WIPO field: Other special machines
• WIPO sector: Mechanical engineering

Abstract

An electric furnace for the continuous melting of frits for inorganic oxidic surface coatings, comprising a substantially rectangular melting chamber, a working chamber separated from the melting chamber by an immersion dam, means for the introduction of raw materials to the melting chamber, and electrodes within the melting chamber for the transmission of electrical energy to the melt, the ratio of the effective electrode surface area to the area of the bottom of the melting chamber being less than about 0.1. Advantageously the supply of energy to the electrodes is regulated by supplying a constant current with a constant output stream, the surface of the melt is covered with about 1 to 10 mm of unmelted frit, the average dwell time of the melt in the furnace is from about 3 to 6 hours, the frit is free from nitrates, the melt is about 5 to 20 cm deep and the frit is introduced thereto from a height at least 50 cm above the level of the melt.