CASTING WITH A SECOND METAL COMPONENT FORMED AROUND A FIRST METAL COMPONENT USING HOT ISOSTACTIC PRESSING

Abstract

The present disclosure generally relates to casting molds including a casting shell surrounding at least a portion of a casting core comprising a first metal component and a hot isostactic pressed second metal component around the first metal component. In one aspect, the first metal component may have a lower melting point than the second metal component. In another aspect, the second metal component may retain some metal powder grain structure.

Claims

1. A casting mold comprising: a casting shell surrounding at least a portion of a casting core comprising a first metal component and a hot isostactic pressed second metal component around the first metal component, wherein the first metal component has a lower melting point than the second metal component and the second metal component retains some metal powder grain structure.

2. The casting mold of claim 1, wherein the first metal component includes at least one of aluminum, nickel, copper, gold, or silver.

3. The casting mold of claim 1, wherein the first metal component includes an alloy.

4. The casting mold of claim 1, wherein the second metal component includes tungsten or a tungsten alloy.

5. The casting mold of claim 1, wherein the second metal component includes molybdenum or a molybdenum alloy.

6. The casting mold of claim 1, wherein the casting shell includes ceramic.

7. The casting mold of claim 1, wherein at least one of the casting shell or the first metal component is formed on a layer-by-layer basis.

8. A method of making a cast component comprising: adding a metal powder to an interior space of a casting shell, wherein the metal powder surrounds at least a portion of a first metal component positioned in the interior space of the casting shell; exposing the metal powder to hot isostactic pressing to consolidate the powder into a second metal component; and removing the casting shell and the first metal component from the second metal component, wherein the first metal component has a lower melting point than the second metal component.

9. The method of claim 8, wherein the first metal component includes at least one of aluminum, nickel, copper, gold, or silver.

10. The method of claim 9, wherein the first metal component includes an alloy.

11. The method of claim 8, wherein the second metal component includes tungsten or a tungsten alloy.

12. The method of claim 8, wherein the second metal component includes molybdenum or a molybdenum alloy.

13. The method of claim 8, where the casting shell comprises ceramic.

14. The method of claim 8, wherein the removing the casting shell comprises breaking.

15. The method of claim 8, wherein the removing the first metal component comprises melting.

16. The method of claim 8, further comprising forming at least one of the casting shell or the first metal component by additively forming the at least one of the casting shell or the first metal component on a layer-by-layer basis, comprising steps of: (a) irradiating a layer of powder in a powder bed to form a fused region; (b) providing a subsequent layer of powder over the powder bed; and (c) repeating steps (a) and (b) using at least two different powder compositions corresponding to at least the casting shell or the first metal component to form at least a portion of the casting core.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1 illustrates a method of forming a cast component in accordance with an embodiment of the present invention.

[0013] FIG. 2 illustrates a method of forming a cast component in accordance with an embodiment of the present invention.

[0014] FIG. 3 illustrates a method of forming a cast component in accordance with an embodiment of the present invention.

[0015] FIG. 4 illustrates a method of forming a cast component in accordance with an embodiment of the present invention.

[0016] FIG. 5 illustrates a method of forming a cast component in accordance with an embodiment of the present invention.

[0017] FIG. 6 illustrates a method of forming a cast component in accordance with an embodiment of the present invention.

[0018] FIG. 7 illustrates a casting shell having a varied geometry that can be used with the present invention.

DETAILED DESCRIPTION

[0019] The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details.

[0020] Referring to the drawings wherein identical reference numerals denote the same elements throughout the various views, FIGS. 1-6 illustrate a method 100 of forming a casting component 110 in accordance with certain aspects of the present disclosure.

[0021] As illustrated in FIG. 1, a first metal component 102 may used in the method 100 of forming the casting component 110. The first metal component 102 may include a low melting point metal and/or alloy including, but not limited to, at least one of aluminum, nickel, copper, gold, and/or silver or combinations or alloys thereof. In addition, first metal component 102 may include a metal that is not a refractory metal. However, the first metal component 102 may include any metal with a lower melting point than the second metal component 110. In an example embodiment, the first metal component 102 may be formed using an additive manufacturing technique to produce a desired and/or intricate shape.

[0022] Referring to FIG. 2, a casting shell 104 may be formed surrounding the first metal component 102. In an aspect, the casting shell 104 may include a ceramic. Although the casting shell 104 is illustrated with a U-shape in FIG. 2, it will be understood by one of ordinary skill in the art that the casting shell 104 may take any shape and/or design depending on the desired shape of the casting component 110 without departing from the scope of the present invention. For example, a casting shell 200 with a more intricate design is illustrated in FIG. 7.

[0023] In an example embodiment, at least one of the casting shell or the first metal component may be formed by additively forming the at least one of the casting shell or the first metal component on a layer-by-layer basis, comprising steps of: (a) irradiating a layer of powder in a powder bed to form a fused/sintered region, (b) providing a subsequent layer of powder over the powder bed, and (c) repeating steps (a) and (b) using at least two different powder compositions corresponding to at least the casting shell or the first metal component to form at least a portion of the casting core.

[0024] A metal powder 106 may be added to an interior space of the casting shell 104 such that at least a portion of the first metal component 102 is surrounded by the metal powder 106, as illustrated in FIG. 3. In an aspect, the metal powder 106 may include, but is not limited to, at least one of molybdenum, niobium, tantalum and/or tungsten or combinations or alloys thereof. However, the metal powder 106 may include any metal powder with a melting point that has a higher than the first metal component 102 without departing from the scope of the present invention.

[0025] In an aspect, the metal powder 106 may exposed to elevated temperature 108 and pressure 108 (e.g., isostactic pressure) to consolidate the metal powder 106 into a second metal component 110, as illustrated in FIG. 4. In an example embodiment, the casting shell 104 including the first metal component 102 and the metal powder 106 may be placed in a containment vessel (not shown). The containment vessel may be heated such that the pressure within the containment vessel is increased. Additionally, an inert gas (e.g., such as argon) may be pumped into the containment vessel to achieve a desired pressure level. For example, the pressure may be increased to between 50 MPa to 350 MPa depending on the metal to be consolidated. In addition, the temperature within the containment vessel may be increased to between 450° C. to 1,400° C. depending on the metal powder to be consolidated.

[0026] By forming the second metal component 110 using hot isostactic pressing, a second metal component 110 may be formed with specific structural/physical properties that differ from the structural properties of a metal component not formed using hot isostactic pressing. For example, a metal component formed using hot isostactic pressing may have fewer internal voids and/or a reduced microporosity than a metal component formed using other processes. In addition, the structural properties of the metal component may also be improved by using hot isostactic pressing. For example, the fatigue resistance of the second metal component 110 may be improved by formation using hot isostactic pressing.

[0027] Referring to FIG. 5, once the metal powder 106 is consolidated into the second metal component 110, the casting shell 104 may be removed from the first metal component 102 and the second metal component 110. For example, the casting shell 104 may be removed by breaking.

[0028] Referring to FIG. 6, the first metal component 102 may be removed by melting the first metal component 102. In an example embodiment, the first metal component 102 may be chosen such that its melting point is lower than the melting point of the second metal component 110. In this way, the first metal component 102 may be melted without melting and/or causing damage to the second metal component 110.

[0029] In the above example, the first metal component 102 is used as a disposable pattern material, analogous to wax in the lost wax process for forming a turbine blade. In addition, the first metal component 102 may be used in conjunction with the second metal component 110 within a lost-wax process. In this case, both metals form a portion of the casting core. The casting core is then surrounded in wax and then a ceramic shell. The wax is removed and in addition, the first metal component 102 is melted away in the same or different heating step that is used to remove the wax. The first metal component 102 can be used as a gate material in the casting process that provides a passage for subsequently molded material after being melted away.

[0030] This written description uses examples to disclose the invention, including the preferred embodiments, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims. Aspects from the various embodiments described, as well as other known equivalents for each such aspect, can be mixed and matched by one of ordinary skill in the art to construct additional embodiments and techniques in accordance with principles of this application.