Methods for centrifugally casting highly reactive titanium metals

Abstract

Methods for centrifugally casting a highly reactive titanium metal involving providing a cold wall induction crucible having a plurality of induction coils and a removable bottom plate, using a power source to heat a titanium metal charge in the induction crucible to obtain a molten metal, preheating a secondary crucible and placing the preheated secondary crucible into a centrifugal casting machine, positioning the centrifugal casting machine having the secondary crucible beneath the induction crucible, withdrawing the bottom plate of the induction crucible and turning off the power source to the induction crucible to allow the molten metal to fall from the induction crucible into the secondary crucible, and accelerating the secondary crucible to centrifugally force the molten metal into a casting mold to produce a cast component.

1 . A method for centrifugally casting a highly reactive titanium metal comprising:
 providing a cold wall induction crucible having a plurality of induction coils and a removable bottom plate;   using a power source to heat a titanium metal charge in the induction crucible to obtain a molten metal;   preheating a secondary crucible and placing the preheated secondary crucible into a centrifugal casting machine;   positioning the centrifugal casting machine having the secondary crucible beneath the induction crucible;   withdrawing the bottom plate of the induction crucible and turning off the power source to the induction crucible to allow the molten metal to fall from the induction crucible into the secondary crucible; and   accelerating the secondary crucible to centrifugally force the molten metal into a casting mold having a facecoat comprising an oxide selected from the group consisting of scandium oxide, yttrium oxide, hafnium oxide, a lanthanide series oxide, and combinations thereof to produce a cast component   
       wherein the secondary crucible comprises ceramic or a niobium liner. 
     
     
         2 . The method of  claim 1  wherein the titanium metal charge comprises a titanium aluminide alloy. 
     
     
         3 . The method of  claim 1  comprising withdrawing the bottom plate of the induction crucible using a method selected from the group consisting of sliding, rotating and dropping. 
     
     
         4 . The method of  claim 1  wherein the cast component comprises a low pressure turbine blade. 
     
     
         5 . The method of  claim 2  comprising using the induction coils of the induction crucible to heat the metal charge to a temperature of from about 1480° C. to about 1557° C. to obtain the molten metal. 
     
     
         6 . The method of  claim 1  wherein the molten metal becomes suspended within the induction crucible. 
     
     
         7 . The method of  claim 2  comprising preheating the secondary crucible to a temperature of at least about 1000° C. when the secondary crucible comprises niobium and at least about 1082° C. when the secondary crucible comprises ceramic. 
     
     
         8 . The method of  claim 1  comprising:
 keeping the secondary crucible stationary for from about 0.5 to about 2 seconds after the molten metal falls into the secondary crucible; and 
 thereafter accelerating the secondary crucible to from about 100 rpm to about 600 rpm within from about 1 second to about 2 seconds to centrifugally force the molten metal into the casting mold. 
 
     
     
         9 . (canceled) 
     
     
         10 . A method for centrifugally casting a highly reactive titanium metal comprising:
 providing a cold wall induction crucible having a plurality of induction coils and a removable bottom plate;   using a power source to heat a titanium metal charge in the induction crucible to obtain a molten metal;   preheating a secondary crucible and placing the preheated secondary crucible into a centrifugal casting machine;   positioning a funnel beneath the induction crucible;   positioning the centrifugal casting machine having the secondary crucible beneath the funnel;   withdrawing the bottom plate of the induction crucible and turning off the power source to the induction crucible to allow the molten metal to fall from the induction crucible through the funnel and into the secondary crucible; and   accelerating the secondary crucible to centrifugally force the molten metal into a casting mold having a facecoat comprising an oxide selected from the group consisting of scandium oxide, yttrium oxide, hafnium oxide, a lanthanide series oxide, and combinations thereof to produce a cast component   wherein the secondary crucible comprises ceramic or a niobium liner.   
     
     
         11 . The method of  claim 10  wherein the titanium metal charge comprises a titanium aluminide alloy. 
     
     
         12 . The method of  claim 10  comprising withdrawing the bottom plate of the induction crucible using a method selected from the group consisting of sliding, rotating and dropping. 
     
     
         13 . The method of  claim 10  wherein the cast component comprises a low pressure turbine blade. 
     
     
         14 . The method of  claim 11  comprising using the induction coils of the induction crucible to heat the metal charge to a temperature of from about 1480° C. to about 1557° C. to obtain the molten metal. 
     
     
         15 . The method of  claim 10  wherein the molten metal becomes suspended within the induction crucible. 
     
     
         16 . The method of  claim 11  comprising preheating the secondary crucible to a temperature of at least about 1000° C. when the secondary crucible comprises niobium and at least about 1082° C. when the secondary crucible comprises ceramic. 
     
     
         17 . The method of  claim 10  comprising:
 keeping the secondary crucible stationary for from about 0.5 to about 2 seconds after the molten metal falls into secondary crucible; and 
 thereafter accelerating the secondary crucible to from about 100 rpm to about 600 rpm within from about 1 second to about 2 seconds to centrifugally force the molten metal into the casting mold. 
 
     
     
         18 . A method for centrifugally casting a highly reactive titanium aluminide comprising:
 providing a cold wall induction crucible having a plurality of induction coils and a slidably removable bottom plate;   using a power source to heat a titanium aluminide charge in the induction crucible to obtain a molten titanium aluminide;   preheating a secondary crucible and placing the preheated secondary crucible into a centrifugal casting machine;   positioning a niobium funnel beneath the induction crucible;   positioning the centrifugal casting machine having the secondary crucible beneath the niobium funnel;   slidably removing the bottom plate of the induction crucible and turning off the power source to the induction crucible to allow the molten titanium aluminide to fall from the induction crucible through the niobium funnel and into the secondary crucible;   keeping the secondary crucible stationary for from about 0.5 to about 2 seconds after the molten titanium aluminide falls into secondary crucible; and   accelerating the secondary crucible to from about 100 rpm to about 600 rpm within from about 1 second to about 2 seconds thereafter to centrifugally force the molten titanium aluminide into a casting mold having a facecoat comprising an oxide selected from the group consisting of scandium oxide, yttrium oxide, hafnium oxide, a lanthanide series oxide, and combinations thereof to produce a cast low pressure turbine blade   
       wherein the secondary crucible comprise ceramic or a niobium liner. 
     
     
         19 . The method of  claim 18  comprising using the induction coils of the induction crucible to heat the metal charge to a temperature of from about 1480° C. to about 1557° C. to obtain the molten metal. 
     
     
         20 . The method of  claim 19  comprising preheating the secondary crucible to a temperature of at least about 1000° C. when the secondary crucible comprises niobium and at least about 1082° C. when the secondary crucible comprises ceramic.