Casting powder

• US 4,124,515 A
• Filed: 10/03/1974
• Issued: 11/07/1978
• Est. Priority Date: 10/03/1973
• Status: Expired due to Term

• Current Assignee: Mannesmann AG (Vodafone Group PLC)
• Original Assignee: Mannesmann AG (Vodafone Group PLC)
• Inventors: Schrewe, Hans, Gruner, Hans, Keuper, Erich, Pleschhutschnigg, Fritz-Peter
• Primary Examiner(s): Ansher, Harold
• Application Number:
  US05/511,786
• Time in Patent Office: 1,496 Days
• Field of Search: 252/62, 252/182, 252/350, 106/38.27, 106/38.3, 106/38.9
• US Class Current: 252/62
• CPC Class Codes: B22D 11/111 by using protecting powders

Abstract

A casting powder for steel having, for example, ground blast furnace slag, and/or sand and caustic lime CaF₂ as basic substances with further additives which include up to 10% of additives decomposing completely at temperatures below 600° C under development of gas whereby the mole-volume of developed gas per mole-weight gas-generating additive (m³ /Kg) is not smaller than 0.5. Ammonium nitrite or ammonium carbonate is preferred whereby the gaseous decomposition products will be nitrogen, water vapor and/or carbon dioxide.

Claims

1. In a method of continuous casting of steel, the use of a casting powder for application to the molten steel, the powder being free from uncombined carbon but including carbonates or nitrites as additives which decompose completely at a temperature of not more than 600°

C. under atmospheric pressure under development of gas pursuant to the decompositioning, for generating a gas barrier against the influx of oxygen into the steel.

2. Method as in claim 1, using a powder, wherein the additives have a specific gas generation constant in ecxess of 0.5 defined as cubic meter developed gas per mole kilogram gas generating substance.

3. Method as in claim 1 wherein the additives used include NH₄ ·

(CO₂ NH₂).

4. Method as in claim 1, wherein the additives used include ammonium nitrites.

5. Method as in claim 1, wherein at least one additive act as a catalyst which provides for catalytic decompositioning of the additive which releases gas upon decompositioning.

6. Method as in claim 5, wherein the catalyst is itself a gas generator.

7. Method as in claim 5, wherein 0.1 to 10% of the powder is such a catalyst.

8. Method as in claim 2, wherein the additives used are 0.5 to 10% by weight of the total casting powder composition.

9. Method as in claim 1, wherein the additives used include (NH₄)₂ CO₃.

10. Method as in claim 1, wherein the additives used include ironcarbonyl.