Unit Cell Titanium Casting

Abstract

A system ( 5 ) and method ( 800 ) for unit cell casting of titanium or titanium-alloys is disclosed herein. The system ( 5 ) comprises an external chamber ( 45 ), a crucible ( 10 ) positioned within the external chamber ( 45 ), an induction coil ( 15 ) positioned around the crucible, an internal chamber ( 40 ) positioned within the external chamber ( 45 ), and a mold ( 30 ) positioned within the internal chamber ( 40 ). The external chamber ( 45 ) is evacuated and a pressurized gas is injected into the evacuated external chamber ( 45 ) to create a pressurized external chamber ( 45 ). An ingot ( 20 ) is melted within the crucible utilizing induction heating generated by the induction coil ( 15 ). The internal chamber ( 40 ) is evacuated to create an evacuated internal chamber ( 40 ). The titanium alloy material of the ingot ( 20 ) is completely transferred into the mold ( 30 ) from the crucible ( 10 ) using a pressure differential created between the external chamber ( 45 ) and the internal chamber ( 40 ).

We claim as our invention the following: 
     
         1 . A method for unit cell casting of titanium or titanium-alloys, the method comprising:
 positioning a mold within an internal chamber;   evacuating an external chamber to create an evacuated external chamber wherein a ceramic crucible containing a titanium alloy ingot is positioned therein;   evacuating the internal chamber to create an evacuated internal chamber having a pressure no greater than 3×10 −2  atmosphere;   injecting a pressurized gas into the evacuated external chamber to create a pressurized external chamber with a pressure in excess of 1 atm;   pre-heating the crucible to a temperature greater than 500° C.;   melting the titanium alloy ingot within the ceramic crucible utilizing induction heating generated by an induction coil;   transferring the completely melted titanium alloy material into the mold from the crucible using a pressure differential created between the external chamber and the internal chamber;   wherein a high pressure differential in maintained between the external chamber and the internal chamber during the transfer of the melted titanium alloy material;   wherein the PLC controls power to the induction coil to position the induction coil relative to the titanium alloy ingot;   wherein the pressure of the internal chamber and the pressure of the external chamber are monitored and communicated to the PLC during the casting process, and wherein the PLC controls the casting process based on the pressure of the internal chamber and the pressure of the external chamber;   wherein the preheating of the crucible results in faster heating and subsequent melting of the titanium alloy material thereby reducing the time necessary to evacuate the material from the crucible into the mold.   
     
     
         2 . The method according to  claim 1  wherein the pressurized gas is argon. 
     
     
         3 . The method according to  claim 1  wherein a frequency generated in the induction coil ranges from 1 kilo-Hertz to 50 kilo-Hertz. 
     
     
         4 . The method according to  claim 1  wherein an atmospheric pressure of the evacuated internal chamber ranges from 3×10 −2  atmosphere to 9.87×10 −7  atmosphere. 
     
     
         5 . The method according to  claim 1  wherein the crucible is a single Yttria-based barium infused shell layer having a thickness ranging from 0.015 inch to 0.060 inch, and comprised of a binder with a slurry ratio between 1:1.5 and 1:3.5. 
     
     
         6 . The method according to  claim 1  wherein a power level to the induction coil is more than 70 kiloWatts. 
     
     
         7 . The method according to  claim 1  wherein the titanium alloy ingot is centered within the ceramic crucible using a centering feature. 
     
     
         8 . The method according to  claim 7  wherein the centering feature is a plurality of stand-offs in a wall of the ceramic crucible. 
     
     
         9 . The method according to  claim 1  wherein an atmospheric pressure of the evacuated internal chamber ranges from 9.87×10 −7  atmosphere to 9.87×10 −13  atmosphere 
     
     
         10 . A system method for unit cell casting of titanium or titanium-alloys, the system comprising:
 an external chamber;   a ceramic crucible positioned within the external chamber;   an induction centered on the upper third of the titanium alloy ingot in the ceramic crucible;   an internal chamber positioned within the external chamber; and   a mold positioned within the internal chamber;   wherein the crucible is preheated to a temperature greater than 500° C.;   wherein the pressure of the internal chamber and the pressure of the external chamber are monitored and communicated to the PLC during the casting process, and wherein the PLC controls the casting process based on the pressure of the internal chamber and the pressure of the external chamber;   wherein the external chamber is evacuated to create an evacuated external chamber wherein the ceramic crucible contains a titanium alloy ingot positioned therein;   wherein a pressurized gas is injected into the evacuated external chamber to create a pressurized external chamber;   wherein the titanium alloy ingot is melted within the ceramic crucible utilizing induction heating generated by the induction coil;   wherein the crucible is composed of Silica and coated with a Yttria based slurry and stucco system;   wherein the internal chamber is evacuated to create an evacuated internal chamber;   wherein the titanium alloy material is completely transferred into the mold from the crucible using a maximum pressure differential created between the external chamber and the internal chamber.   
     
     
         11 . A method for unit cell casting of titanium or titanium-alloys, the method comprising:
 pre-heating a ceramic crucible to a temperature greater than 500° C.;   evacuating an external chamber to create an evacuated external chamber wherein the ceramic crucible contains a titanium alloy ingot is positioned therein;   evacuating the internal chamber to create an evacuated internal chamber having a pressure no greater than 3×10 −2  atmosphere;   melting the titanium alloy ingot within the ceramic crucible utilizing induction heating generated by an induction coil wherein a position of the induction coil begins at a upper third of the titanium alloy ingot and during the melting of the titanium alloy ingot the position of the induction coil is lowered relative to the titanium alloy ingot to terminate at a bottom of the titanium alloy ingot;   injecting a pressurized gas into the evacuated external chamber to create a pressurized external chamber with a pressure in excess of 1 atmosphere, wherein the pressure differential is at a maximum; and   utilizing a high pressure differential between the external chamber and the internal chamber to flow the completely melted titanium alloy material into the mold from the crucible.   
     
     
         12 . The method according to  claim 11  wherein the pressurized gas is argon. 
     
     
         13 . The method according to  claim 11  wherein a frequency generated in the induction coil ranges from 1 kilo-Hertz to 50 kilo-Hertz. 
     
     
         14 . The method according to  claim 11  wherein an atmospheric pressure of the evacuated internal chamber ranges from 3×10 −2  atmosphere to 9.87×10 −7  atmosphere. 
     
     
         15 . The method according to  claim 11  wherein the titanium alloy ingot is centered within the ceramic crucible using a centering feature. 
     
     
         16 . The method according to  claim 11  wherein the internal chamber is preheated at a temperature ranging from 1150° C. to 1250° C. 
     
     
         17 . The method according to  claim 11  wherein a PLC determines when to melt the titanium alloy based on the pressures of the internal chamber and the external chamber. 
     
     
         18 . The method according to  claim 11  wherein the PLC determines when to change the pressure of internal chamber and the external chamber. 
     
     
         19 . The method according to  claim 11  wherein an atmospheric pressure of the evacuated internal chamber ranges from 9.87×10 −7  atmosphere to 9.87×10 −13  atmosphere 
     
     
         20 . The method according to  claim 15  wherein the centering feature is a plurality of stand-offs in a wall of the ceramic crucible.