Crucible For Use In A Directional Solidification Furnace

Abstract

A directional solidification furnace comprises a crucible assembly including a crucible for containing a melt having walls and a base with an opening therein, a crucible support for supporting the crucible, and a lid covering the crucible. A plate is received in the opening in the base. The plate has a higher thermal conductivity than that of the base. The base can include a composite having an additive such that the composite base has a higher thermal conductivity than a comparable without the additive.

1 . A directional solidification furnace comprises:
 a crucible assembly including:
 a crucible for containing a melt, the crucible including walls and a base, the base having an opening therein; 
 a crucible support supporting the crucible, 
 a lid covering the crucible; and 
 a plate received in the opening in the base, the plate having a higher thermal conductivity than that of the base. 
   
     
     
         2 . The directional solidification furnace of  claim 1  wherein the opening extends through the base, the opening having sloped walls of a first angle and the plate having sloped walls of a second angle complementary to the first angle. 
     
     
         3 . The directional solidification furnace of  claim 1  wherein the opening extends through the base, the opening defined by a void in the base having four sides, a portion of the base extending inward from the sides to form a ledge structure. 
     
     
         4 . The directional solidification furnace of  claim 1  wherein the plate has a thickness that is substantially equal to a thickness of the base. 
     
     
         5 . The directional solidification furnace of  claim 1  wherein the plate is secured to the base by a bonding agent. 
     
     
         6 . The directional solidification furnace of  claim 1  wherein the plate has a thermal conductivity at least twice that of the base. 
     
     
         7 . The directional solidification furnace of  claim 1  further comprising:
 a heat exchanger disposed beneath the base of the crucible support. 
 
     
     
         8 . The directional solidification furnace of  claim 1  wherein the crucible is made of graphite. 
     
     
         9 . The directional solidification furnace of  claim 1  further comprising:
 one or more movable heaters removably disposed around the crucible support. 
 
     
     
         10 . The directional solidification furnace of  claim 1  further comprising:
 removable insulation disposed around the crucible. 
 
     
     
         11 . The directional solidification furnace of  claim 1  wherein the crucible walls include four walls joined together such that the liquid melt is contained therein. 
     
     
         12 . The directional solidification furnace of  claim 1  wherein the base has an upper surface and a lower surface, the opening not extending through the base, the opening disposed in the lower surface and forming a portion of a recess in the lower surface. 
     
     
         13 . The directional solidification furnace of  claim 12  wherein the plate is disposed in the recess and is separated from the melt in the crucible by the base. 
     
     
         14 . A directional solidification furnace comprises:
 a crucible assembly including:
 a crucible for containing a melt, the crucible including walls and a composite base; 
 a crucible support supporting the crucible, 
 a lid covering the crucible; and 
 the composite base including an additive such that the composite base has a higher thermal conductivity than a comparable base without the additive. 
   
     
     
         15 . The directional solidification furnace of  claim 14  wherein the additive is selected from the group comprising: MgO, SiC, AIN and TiO 2 . 
     
     
         16 . The directional solidification furnace of  claim 14  wherein at least a portion of the crucible walls include the additive such that the portion of the crucible walls has a higher thermal conductivity than a portion of the wall without the additive. 
     
     
         17 . The directional solidification furnace of  claim 16  wherein the additive is selected from the group comprising: MgO, SiC, AIN and TiO 2 . 
     
     
         18 . A method of producing an ingot in a directional solidification furnace comprising:
 melting a silicon charge in a crucible of the furnace to form a liquid melt, the crucible including a base, at least a first portion of the base having a higher thermal conductivity than a second portion of the base; and   transferring heat from the melt through at least the base of the crucible, wherein heat is transferred through the first portion of the base at an increased rate compared to the second portion,   wherein the transfer of heat from the melt results in the solidification of the melt and production of the ingot.   
     
     
         19 . The method of  claim 17  further comprising, prior to melting the silicon charge, loading the crucible with the silicon charge. 
     
     
         20 . The method of  claim 17  wherein heat is transferred through the first portion of the base having a thermal conductivity at least double that of the second portion of the base.