Process for the protection against corrosion of cast iron in boiling concentrated sulfuric acid

US4145393A · kind A · utility

Assignee

• Hoechst GmbH · DE

Inventors

• Helmold von Plessen · Kelkheim, DE
• Edmund Bassler · Schwaikheim, DE

Key dates

• Filing date: Jun 16, 1977
• Grant date: Mar 20, 1979
• Expiry date: Jun 16, 1997

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C23F11/04
• WIPO field: Surface technology, coating
• WIPO sector: Chemistry

Abstract

Gray cast iron can be protected against corrosion in boiling concentrated sulfuric acid if the acid contains precious metals such as gold or the metals of the platinum group. It is possible to add small amounts of compounds of the precious metal to the acid or to bring both the gray cast iron and the acid into contact with metal sheets or wires of the precious metal. It is also possible to use small amounts of the precious metal as an alloying element of the gray cast iron.