Abstract:
The present application provides a method of producing a component. The method may include the steps of creating a dissolvable ceramic material mold in an additive manufacturing process, casting a metallic material in the dissolvable ceramic material mold, creating the component, and dissolving the dissolvable ceramic material. The component may be a turbine component.

Description:
TECHNICAL FIELD 
       [0001]    The present application and the resultant patent relate generally to gas turbine engines and more particularly relate to three-dimensional manufacturing methods and systems for complex hot gas path turbine components and the like with improved cooling capacity. 
       BACKGROUND OF THE INVENTION 
       [0002]    Gas turbine engine components such as buckets, nozzles, and other components in the hot gas path, may be produced in an investment casting process. Generally described, a ceramic core and shell may be produced separately. The ceramic core may be produced by pouring a ceramic slurry into a metal die and solidifying the ceramic material. The ceramic core then may be encased in wax and a ceramic shell may be formed around the wax pattern. The wax that encases the ceramic core then may be removed to form a ceramic mold in which a metallic component may be cast. Once the metallic component is cooled, the shell materials may be stripped away and the ceramic core may be leached away to form the finished product. Other types of component casting methods may be used. 
         [0003]    Components having complex geometry such as internal passages and voids therein may be difficult to cast or otherwise created. For example, such complex geometries may include buckets and nozzles with internal airflow passages for cooling. The tooling used for the manufacture of such parts may be expensive and time consuming to create. Moreover, the chemicals used to leach away the ceramic material may be toxic and hazardous to use. 
       SUMMARY OF THE INVENTION 
       [0004]    The present application and the resultant patent thus provide a method of producing a component. The method may include the steps of creating a dissolvable ceramic material mold in an additive manufacturing process, casting a metallic material in the dissolvable ceramic material mold, creating the component, and dissolving the dissolvable ceramic material. The component may be a turbine component. 
         [0005]    The present application and the resultant patent further provide a combined core and mold for creating a turbine component. The combined core and mold may include an inner core and an outer mold. The inner core and the outer mold may define a sidewall and a number of inner ribs therebetween. The inner core and the outer mold may be made from a dissolvable ceramic material suitable for an additive manufacturing process. The turbine component may be an airfoil or other type of hot gas path component. 
         [0006]    The present application and the resultant patent further provide a method of producing a turbine airfoil with a number of internal channels. The method may include the steps of creating a combined core and mold of a dissolvable ceramic material in an additive manufacturing process, casting a metallic material in the combined core and mold, creating the turbine airfoil, and dissolving the dissolvable ceramic material within the internal channels. 
         [0007]    These and other features and improvements of the present application and the resultant patent will become apparent to one of ordinary skill in the art upon review of the following detailed description when taken in conjunction with the several drawings and the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a schematic diagram of a gas turbine engine showing a compressor, a combustor, a turbine, and a load. 
           [0009]      FIG. 2  is a sectional view of an airfoil that may be used with the gas turbine engine of  FIG. 1 . 
           [0010]      FIG. 3  is a sectional view of a core that may be used to manufacture the airfoil of  FIG. 2 . 
           [0011]      FIG. 4  is a sectional view of a combined core and mold that may be used to manufacture the airfoil of  FIG. 2 . 
           [0012]      FIG. 5  is a flowchart showing exemplary steps in creating the core of  FIG. 3  and/or the combined core and mold of  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    Referring now to the drawings, in which like numerals refer to like elements throughout the several views,  FIG. 1  shows a schematic view of gas turbine engine  10  as may be used herein. The gas turbine engine  10  may include a compressor  15 . The compressor  15  compresses an incoming flow of air  20 . The compressor  15  delivers the compressed flow of air  20  to a combustor  25 . The combustor  25  mixes the compressed flow of air  20  with a compressed flow of fuel  30  and ignites the mixture to create a flow of combustion gases  35 . Although only a single combustor  25  is shown, the gas turbine engine  10  may include any number of combustors  25 . The flow of combustion gases  35  is in turn delivered to a turbine  40 . The flow of combustion gases  35  drives the turbine  40  so as to produce mechanical work. The mechanical work produced in the turbine  40  drives the compressor  15  via a shaft  45  and an external load  50  such as an electrical generator and the like. 
         [0014]    The gas turbine engine  10  may use natural gas, various types of syngas, liquid fuels, and/or other types of fuels and blends thereof. The gas turbine engine  10  may be any one of a number of different gas turbine engines offered by General Electric Company of Schenectady, N.Y., including, but not limited to, those such as a 7 or a 9 series heavy duty gas turbine engine and the like. The gas turbine engine  10  may have different configurations and may use other types of components. Other types of gas turbine engines also may be used herein. Multiple gas turbine engines, other types of turbines, and other types of power generation equipment also may be used herein together. 
         [0015]      FIG. 2  shows an example of a turbine airfoil  55  that may be used with the gas turbine engine  10  of  FIG. 1 . The airfoil  55  may include a main sidewall  60 . The main sidewall  60  may extend from a leading edge  65  to a trailing edge  70 . Within the main sidewall  60 , the airfoil  55  may have a number of internal ribs  75 . The main sidewall  60  and the internal ribs  75  may define any number of channels  80  therein. The channels  80  may permit a flow of a fluid such as air to provide cooling to the airfoil  55 . A number of crossover holes  85  also may extend through the internal ribs  75  and between the channels  80 . The airfoil  55  is described herein for the purpose of example only. Many different types of airfoils with many different internal configurations may be used. Likewise, many different types of hot gas path components and other types of turbine components may be used. 
         [0016]    As described above, the airfoil  55  traditionally has been produced in an investment casting process. Specifically, the channels  80  may be formed via a ceramic core while the sidewall  60  may be formed within an outer ceramic mold. Certain shapes and configurations, however, may be difficult to manufacture in such an investment casting process. 
         [0017]    Instead of the investment casting process and the like, an airfoil  100  or other type of turbine component  110  as may be described herein may be manufactured in an additive manufacturing system. Such an additive manufacturing system may include a three-dimensional printing process, an additive printing process, and the like. Examples of such systems and processes may include extrusion base techniques, jetting, selective laser sintering, powder/binder jetting, electron beam melting, stereo-lithographic processes, and the like. Specifically, binder jetting is an additive manufacturing process in which a liquid binding agent is selectively deposited to join powder particles. Layers of material then may be bonded to form an object. The object thus develops through the layering of the powder and the binding. Binder jetting may be similar to traditional paper printing in that the binder functions like the ink as it moves across the layers of powder which function like paper to form the final product. Other types of manufacturing processes may be used herein. 
         [0018]    Such a binder jetting process may be used with ceramic materials and the like. More particularly, the process may be used with water soluble ceramic materials. For example, a suitable material may include about sixty to seventy weight percent (60 to 70%) alumina (AL 2 O 3 ) flour, about fifteen to twenty-five weight percent (15 to 25%) zircon (ZrSiO 4 ) flour, about five to fifteen weight percent (5 to 15%) sodium hydrogen phosphate (Na 2 HPO 4 ), and about five weight percent (5%) of cane sugar. More preferably, the ceramic core may contain about sixty-five weight percent (65%) of alumina flour, about twenty weight percent (20%) of zircon flour, about ten weight percent (10%) of sodium hydrogen phosphate, and about five weight percent (5%) of cane sugar. In this composition, the alumina and the zircon may be used primarily as fillers. The sodium hydrogen phosphate may be a binding agent. The cane sugar may improve the surface smoothness and the wet strength of the resultant water-soluble ceramic core. Other types of ceramics, water soluble ceramics, and other materials may be used herein. 
         [0019]      FIG. 3  shows an example of a core  120  that may be used to create the airfoil  100  or other type of turbine component  110  and the like. As is shown, the core  120  corresponds to the channels  80  and crossover holes  85  with the space in-between corresponding to the internal ribs  75 . The core  120  may be made from a ceramic material and more specifically, may be made from a water soluble ceramic material similar to that described above and the like. Other types of materials may be used herein. The core  120  may be made from an additive manufacturing process such as the binder jetting process described above and the like. Other types of additive manufacturing processes including but not limited to those described above also may be used herein. Other components and other configurations may be used herein. 
         [0020]    Once produced, the core  120  then may be used in a conventional investment casting process and the like so as to form the outer mold or other type of structure. Alternatively, a combined core and mold  130  may be created as is shown in  FIG. 4 . The combined core and mold  130  may include the core  120  substantially as described above and an outer mold  140 . The sidewall  60  and other components of the airfoil  100  may be defined between the core  120  and the outer mold  140 . Both the core  120  and the outer mold  140  may be created at the same time in the additive manufacturing processes described herein as opposed to the separate structures from in the traditional manufacturing processes. Again, a ceramic material and more preferably a water soluble ceramic material may be used herein. Other components and other configurations may be used herein. 
         [0021]      FIG. 5  shows a flowchart of exemplary steps in carrying out the methods described herein in whole or in part. At step  150 , the desired dimensions of the airfoil  100  or other type of turbine component  110  may be input into the additive manufacturing system. At step  160 , the additive manufacturing system may print or otherwise produce the core  120 , the combined mold and core  130 , the outer mold  140 , or other type of mold and the like in the additive manufacturing process. At step  170 , the core  120  may be used in a conventional investment casting process and the like to create the airfoil  100  and/or the metallic material may be poured or otherwise casted about the combined mold and core  130  so as to create the airfoil  100 . At step  180 , the core  120  and/or the combined mold and core  130  may be dissolved via water and the like from the airfoil  100 . Dissolving the core  130  thus creates the cooling chambers  80  and other types of internal geometries within the airfoil  100 . The outer mold  140  may be dissolved as well or may be otherwise stripped away. The airfoil  100  may now be substantially ready for use and/or further processing. The methods steps described herein are not exclusive. Other or different steps may be used in any desired order. 
         [0022]    The methods and systems described herein thus provide for the production of the airfoil  100 , other types of turbine components  110 , and other components in a fast and efficient manner. Moreover, the airfoil  100  may have advanced and effective internal cooling&#39; geometries formed herein. Further, the water soluble ceramic material may be used for the three-dimensional printing of the core  120  and the like so as to avoid the use of hazardous chemicals generally required for leaching. Any suitable ceramic material may be used for three-dimensional printing of the core  120  and/or the combined mold and core  130 . The binder jetting processes described herein may be used for three-dimensional printing with any type of ceramic. Other types of additive manufacturing processes may be used herein. 
         [0023]    It should be apparent that the foregoing relates only to certain embodiments of the present application and the resultant patent. Numerous changes and modifications may be made herein by one of ordinary skill in the art without departing from the general spirit and scope of the invention as defined by the following claims and the equivalents thereof