Refractory article for molten metal handling

Abstract

An article suitable for contact with molten metal, comprising at least one wall formed from refractory material, the wall including a region having a thermal conductivity which is lower than that of the refractory material. The lower thermal conductivity region of the wall of the article may be an air-filled cavity in the wall, and the article may be a feeder sleeve.

What is claimed is:  
     
         1 . An article suitable for contact with molten metal, comprising at least one wall formed from refractory material, the wall including a region having a thermal conductivity which is lower than that of the refractory material.  
     
     
         2 . An article according to    claim 1   , in which the lower thermal conductivity region comprises a material having a lower thermal conductivity than that of the refractory material.  
     
     
         3 . An article according to    claim 1    or    claim 2   , in which the lower thermal conductivity region is located between at least two spaced apart portions of the refractory material of the wall.  
     
     
         4 . An article according to any one of    claims 1    to    3   , in which the lower thermal conductivity region comprises a cavity within the wall.  
     
     
         5 . An article according to    claim 4   , in which the cavity contains at least a partial vacuum.  
     
     
         6 . An article according to    claim 4    when dependent upon    claim 2   , in which the lower thermal conductivity region comprises said cavity containing said lower thermal conductivity material.  
     
     
         7 . An article according to    claim 2    or any claim dependent thereon, in which the lower thermal conductivity material is a gas.  
     
     
         8 . An article according to    claim 7   , in which the gas is air.  
     
     
         9 . An article according to any one of    claims 2    to    4    or    6   , in which the lower thermal conductivity material is a solid.  
     
     
         10 . An article according to    claim 9   , in which the material is a foam.  
     
     
         11 . An article according to    claim 1    or    claim 2   , in which the lower thermal conductivity region comprises a region of refractory material having a lower density than that of the remainder of the refractory material of the wall.  
     
     
         12 . An article according to    claim 11   , in which the lower density refractory material is contained in a hollow casing insert.  
     
     
         13 . An article according to    claim 1    or    claim 2   , in which the lower thermal conductivity region comprises a hollow casing insert containing a gas.  
     
     
         14 . An article according to    claim 4   , in which the cavity contains a framework of ribs.  
     
     
         15 . An article according to any preceding claim, comprising a feeder article.  
     
     
         16 . An article according to any preceding claim, comprising a lining for a molten metal handling vessel.  
     
     
         17 . An article according to any preceding claim, comprising a sleeve.  
     
     
         18 . An article according to any one of    claims 1    to    16   , comprising a board.  
     
     
         19 . A method of manufacturing an article according to any preceding claim, comprising forming the lower thermal conductivity region of the wall of refractory material at the same time as the remainder of the wall is formed.  
     
     
         20 . A method according to    claim 19   , in which the lower thermal conductivity region of the wall comprises a cavity which is formed by means of one or more formers.  
     
     
         21 . A method of manufacturing an article according to any one of    claims 1    to    18   , comprising forming the lower thermal conductivity region of the wall of refractory material subsequently to the remainder of the wall being formed.  
     
     
         22 . A method according to    claim 21   , in which the lower thermal conductivity region of the wall comprises a cavity which is formed by the removal of some of the material of the wall subsequent to the wall having been formed.  
     
     
         23 . A method according to    claim 21   , in which the lower thermal conductivity region of the wall is created during use once the article contacts hot molten metal.  
     
     
         24 . A method according to    claim 23   , in which the lower thermal conductivity region of the wall is formed by a sacrificial material which, once the article contacts the hot molten metal, changes its form to create the lower thermal conductivity region.