Glass ceramic material, method for producing the same and spark plug containing such a glass ceramic material

US6699807B2 · kind B2 · utility

Assignee

• Robert Bosch GmbH · DE

Inventors

• Heinz Geier · Leonberg, DE
• Rudolf Pollner
• Imke Koengeter · Stuttgart, DE
• Ulrich Eisele · Stuttgart, DE

Key dates

• Filing date: Mar 23, 2002
• Grant date: Mar 2, 2004
• Expiry date: Mar 23, 2022

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C03C2214/08
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

A glass ceramic, for use as a resistor or a gas-tight glass ceramic solder for use in a spark plug, includes a fused seal of a starting glass fused from a starting mixture containing SiO2, Al2O3, TiO2 and CaO, the fused seal including crystalline phases in at least some areas. A method for producing such a glass ceramic provides for the starting glass to be processed in a first method step to form a starting material, which is heated for a first period of time in a second method step from a starting temperature, which is below the softening temperature of the starting glass, to a fusion temperature, which is above the softening temperature of the starting glass, and is kept at that temperature for a second period of time and finally is cooled again. A spark plug may include a terminal stud and a center electrode, which are electrically connected across a resistor that is formed in at least some areas by the glass ceramic.