Process for improving the surface cleanliness of sheet steel

US4209366A · kind A · utility

Assignee

• Centre De Recherches Metallurgiques-Centrum Voor Research in De Metallurgie · BE

Inventors

• Vincent Leroy · Laval, FR
• Joseph H. Richelmi · Liège, BE

Key dates

• Filing date: Jun 30, 1978
• Grant date: Jun 24, 1980
• Expiry date: Jun 30, 1998

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C23G5/00
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

Before or during the coiling of cold-rolled sheet steel for stamping, the sheet steel is covered with a substance comprising an agent capable of reacting with amorphous carbon present on the sheet as a contaminant so as to form a volatile compound, such as carbon monoxide or carbon disulphide, during subsequent annealing of the coil. Suitable substances for forming carbon monoxide are (1) certain gels (e.g., gels deposited in the form of a very thin layer from a solution of a soluble silicate such as sodium, potassium, or lithium orthosilicate) which liberate water of adsorption on heating, as during annealing, which water of adsorption reacts with the carbon contaminant to form carbon monoxide; and (2) certain salts [e.g., Ba(OH).sub.2. 8H.sub.2 O, Ca(OH).sub.2, and Zr(OH).sub.4 ] which liberate water of crystallization or water of constitution on heating, as during annealing, which waters of crystallization and constitution react with the carbon contaminant to form carbon monoxide. Suitable substances for forming carbon disulphide are thiourea, diethyl thiourea, and sulphonates.