Anti-alumina-buildup refractories for casting nozzles

Abstract

Disclosed is anti-alumina-buildup refractories for casting nozzles, which comprises a refractory aggregate including 20 mass % or more of CaO component, and 10 mass % or more of clinker particles each containing CaO as a mineral phase, on the basis of 100 mass % of the entire composition. At least a part of the surfaces of the CaO exposed from the surfaces of the corresponding clinker particles is formed with a CaCO 3 film. The CaCO 3 film releases CO 2 gas through thermal decomposition to smooth an operative surface of the nozzle so as to prevent the accretion of metal thereon, so that CaO is continuously supplied to alumina attached on the operative surface to prevent alumina buildup. In addition, the CaCO 3 film effectively prevents the hydration of CaO due to a hydration reaction.

1 . Anti-alumina-buildup refractories for casting nozzles, comprising a refractory aggregate which includes 20 mass % or more of CaO component, and 10 mass % or more of clinker particles on the basis of 100 mass % of the entire composition, each of said clinker particles containing CaO as a mineral phase, wherein at least a part of the surfaces of the CaO exposed from the surfaces of said corresponding clinker particles is formed with a CaCO 3  film. 
     
     
         2 . The anti-alumina-buildup refractories as defined in  claim 1 , wherein said CaCO 3  film has a thickness ranging from 0.1 to 5 μm.