Method of coating cathode wires by cataphoretic coating

US4806218A · kind A · utility

Assignee

• Nokia Graetz · DE

Inventors

• Herbert Hemminger · Schorndorf, DE
• Michael Schlipf · Schorndorf, DE

Key dates

• Filing date: Sep 4, 1987
• Grant date: Feb 21, 1989
• Expiry date: Sep 4, 2007

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C25D13/02
• WIPO field: Surface technology, coating
• WIPO sector: Chemistry

Abstract

Oxide cathode wires are produced by coating tungsten wires with emissive material by cataphoretic coating. It is important for the coating to have a substantially uniform thickness over the entire surface of the wire. This is achieved in a simple manner by reversing the polarity of the direction of current flow for a short time at the beginning of the coating process, so that the tungsten wire to be coated is connected as an anode. The remainder of the coating process is performed in a known manner with a tungsten wire connected as a cathode.