Refractory material for casting a rare-earth alloy and its production method as well as method for casting the rare-earth alloys

Abstract

Rare-earth alloy is cast into a sheet ( 6 ) or the like by using a tundish ( 3, 13 ). The refractory material of the tundish used for casting does not necessitate preheating for improving the flowability of the melt ( 2 ). The refractory material used essentially consists of 70 wt % or more of Al 2 O 3 and 30 wt % or less of SiO 2 , or 70 wt % or more of ZrO 2 and 30 wt % or less of one or more of Y 2 O 3 , Ce 2 O 3 , CaO, MgO, Al 2 O 3 , TiO 2 and SiO 2 . The refractory material has 1 g/cm 3 or less of bulk density, has 0.5 kcal/(mh° C.) or less of thermal conductivity in the temperature range of from 1200 to 1400° C., and has 0.5 wt % or less of ratio of ignition weight-loss under the heating condition of 1400° C. for 1 hour.

1 - 20 . (canceled)  
   
   
       21 . An apparatus for casting rare earth alloy comprising: 
 pouring means for receiving and pouring molten alloy, wherein said pouring means is composed of refractory material that consists of 70 wt % or more of Al 2 O 3  and 30 wt % or less of SiO 2  has 1 g/cm 3  or less of bulk density, has 0.5 kcal/(mh° C.) or less of thermal conductivity in the temperature range from 1200 to 1400° C., and has 0.5 wt % or less of ratio of ignition weight-loss under the heating condition of 1400° C. for 1 hour.    
   
   
       22 . The apparatus according to  claim 21 , wherein said refractory material contains 70 wt % or more of alumina fiber.  
   
   
       23 . The apparatus according to  claim 21 , wherein said refractory material contains 70 wt % of alumina fiber and mullite fiber in total.  
   
   
       24 . An apparatus for casting rare earth alloy, comprising: 
 pouring means for receiving and pouring molten alloy, wherein said pouring means is composed of refractory material that consists of 70 wt % or more of ZrO 2  and 30 wt % or less of one or more of Y 2 O 3 , Ce 2 O 3 , CaO, MgO, Al 2 O 3 , TiO 2  and SiO 2  has 2 g/cm 3  or less of bulk density, has 0.5 kcal/(mh° C.) or less of thermal conductivity in the temperature range of from 1200 to 1400° C., and has 0.5 wt % or less of ratio of ignition weight loss under the heating condition of 1400° C. for 1 hour.    
   
   
       25 . The apparatus according to  claim 24 , wherein said refractory material contains 70 wt % or more of one or more of zirconia fiber, zirconia whisker, stabilized zirconia fiber and stabilized zirconia whisker.  
   
   
       26 . The apparatus according to  claim 21 , wherein said pouring means is a tundish.  
   
   
       27 . The apparatus according to  claim 26 , wherein the refractory material contains 70 wt % of alumina fiber.  
   
   
       28 . The apparatus according to  claim 26 , wherein the refractory material contains 70 wt % of alumina fiber and mullite fiber in total.  
   
   
       29 . The apparatus according to  claim 24 , wherein said pouring means is a tundish.  
   
   
       30 . The apparatus according to  claim 29 , wherein the refractory material contains 70 wt % or more of one or more of zirconia fiber, zirconia whisker, stabilized zirconia fiber and stabilized whisker.