US3698467A - Method of removing silaceous cores from nickel and cobalt superalloy castings - Google Patents
Method of removing silaceous cores from nickel and cobalt superalloy castings Download PDFInfo
- Publication number
- US3698467A US3698467A US103544A US3698467DA US3698467A US 3698467 A US3698467 A US 3698467A US 103544 A US103544 A US 103544A US 3698467D A US3698467D A US 3698467DA US 3698467 A US3698467 A US 3698467A
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- US
- United States
- Prior art keywords
- silaceous
- nickel
- cores
- core
- casting
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 238000000034 method Methods 0.000 title claims description 14
- 238000005266 casting Methods 0.000 title abstract description 24
- 229910000601 superalloy Inorganic materials 0.000 title abstract description 14
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 title description 14
- 239000010941 cobalt Substances 0.000 title description 7
- 229910017052 cobalt Inorganic materials 0.000 title description 7
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 title description 7
- 229910052759 nickel Inorganic materials 0.000 title description 6
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 claims abstract description 10
- 229910000027 potassium carbonate Inorganic materials 0.000 claims abstract description 5
- 239000003513 alkali Substances 0.000 claims description 5
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims description 3
- 238000009835 boiling Methods 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 abstract description 3
- 239000000919 ceramic Substances 0.000 abstract description 2
- 239000011162 core material Substances 0.000 description 30
- 239000000243 solution Substances 0.000 description 15
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 10
- 229910045601 alloy Inorganic materials 0.000 description 9
- 239000000956 alloy Substances 0.000 description 9
- 239000000463 material Substances 0.000 description 8
- 229910000288 alkali metal carbonate Inorganic materials 0.000 description 5
- 150000008041 alkali metal carbonates Chemical class 0.000 description 5
- 238000005260 corrosion Methods 0.000 description 5
- 230000007797 corrosion Effects 0.000 description 5
- 239000002585 base Substances 0.000 description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical group O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 3
- 230000002411 adverse Effects 0.000 description 3
- 150000001247 metal acetylides Chemical class 0.000 description 3
- 238000005058 metal casting Methods 0.000 description 3
- 238000011282 treatment Methods 0.000 description 3
- 239000002253 acid Substances 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 239000003518 caustics Substances 0.000 description 2
- 239000000470 constituent Substances 0.000 description 2
- 238000002386 leaching Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 235000012239 silicon dioxide Nutrition 0.000 description 2
- 241000543381 Cliftonia monophylla Species 0.000 description 1
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 239000005350 fused silica glass Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 150000004679 hydroxides Chemical class 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 239000011591 potassium Substances 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 229910052715 tantalum Inorganic materials 0.000 description 1
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D29/00—Removing castings from moulds, not restricted to casting processes covered by a single main group; Removing cores; Handling ingots
- B22D29/001—Removing cores
- B22D29/002—Removing cores by leaching, washing or dissolving
Definitions
- the castings to be leached are immersed in an alkali metal carbonate solution at an elevated temperature, generally in excess of 200 F.
- the alkali metal carbonate solution is preferably saturated with the salt, but can be as low as w/o. Below about 25 w/o, insufficient alkali carbonate is provided to remove the silaceous core in a reasonable time.
- the temperature requirements are simply that the solution and the silaceous core must be sufficiently hot to leach the silaceous material in a reasonable amount of time. We have found that the solution should be above about 200 F preferably above boiling. Temperatures above 2l2 F.
- the component and the solution are realized by placing the component and the solution in a pressure vessel, commonly called an autoclave, having a heating element wrapped about the outside and arranged to raise the temperature to that which is desired.
- a pressure vessel commonly called an autoclave
- the time of the treatment is important insofar as the core is removed from the component when using the aqueous solution of alkali metal carbonate.
- potassium carbonate is highly desirable as the leachantbecause it effectively removes the silaceous material and does not adversely affect the surface of the component.
- the silaceous material which forms the core is quartz or 2 fused silica and is essentially pure silica having a melting point above that of the casting.
- FIG. 2 provides a 1,000X magnification of a'nickel-base superalloy casting which had the core removed by potassium hydroxide also. In both cases, it can be seen that deep fissures appear on the surface of the casting. It is believed that the potassium hydroxide not only reacts with the silaceous material of the core to dissolve it, but also reacts with carbides which were disposed near the surface of the alloy. The pockets of fissures on the surface are due to the carbides washing away because of 'the reaction with: the potassium hydroxide.
- FIG. 2
- the rather long dark lines extending ,down from the surface of the'casting in FIGS. 1 and 2 are corrosion lines which weaken the surface of the alloy.
- FIG. 3 of the drawings a nickel-base superalloy component which has been treated according to the process of the present invention is shown at a 500x magnification. As-can be seen, neither pitting nor corrosion from the core removal treatment nor alloy depletion occurred.
- cores from nickeland cobaltbase superalloy castings can be removed according tov the present process.
- Those alloys generally contain 5 to 25 w/o Cr, 5 to 15 w/o molybdenum, tantalum or tungsten, 2 to 8 w/o aluminum and titanium, less than 1 w/o carbide and the balance nickel and/or cobalt.
- Representative of the superalloys are those identified in the industry on the following Table I.
- a method of removing silaceous cores from nickel or cobalt superalloy castings the steps which comprise: forming an aqueous solution of alkali metal carbonate, said solution containing at least 25 weight percent alkali metal carbonate and being free of substantial quansuperalloy casting having a silaceous core in said solution and then heating to dissolve said core from said 1 casting.
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Manufacture And Refinement Of Metals (AREA)
Abstract
The removal of silaceous ceramic cores from nickel- or cobaltbased superalloy casting is effectuated by heating the casting in a solution of potassium carbonate.
Description
United States Patent [15] 3,698,467 Fassler et al; [451 Oct. 17, 1972 [54] METHOD OF REMOVING SILACEOUS [56] References Cited CORES FROM NICKEL AND COBALT SUPERALLOY CASTINGS UNITED STATES T T [72] Inventors: Michael H. Fa'ssler, Middletown; 1 gammond h g V P b V oungm 0th 3,617,747 11/1971 Wilkinson et al "164/132 x 1 Assignee= United c t p qm East Primary Eiaminer-J. Spencer Overholset Hartford Comb Assistant Exkzminer-John E Roethel 22 Filed: Jam 4 1971 Attorney-Owen J. Meegan 21 Appl -No; 103,544 [57] ABSTRACT The removal of 'silaceoiis ceralnfc cores from nickel- 52 US. Cl ..164/l32 or cobalt based superanoy casting is effectuated by [51] Int. Cl. .B22d 29/00 limiting the casting in a solution of potassium cap [58] Field of Search....l64/l32-; 23/312 R; 134/2, 19,
bonate.
3 Claims, 3 Drawing Figures I 1 METHOD OF REMOVING SILACEOUS CORES FROM NICKEL AND COBALT SUPERALLOY CASTINGS BACKGROUND OF THE INVENTION 1 Field of the Invention This invention relates toa method of removing silaceous ceramic cores from metal castings and particularly, to the removal of such cores from air cooling passages of gas turbine components which are formed of high temperature nickelor cobalt-base superalloys. In the manufacture of metal castings, it is frequently very difficult to completely remove the silaceous material forming the core without adversely affecting the chemical composition of the surface.
2. Descriptionof the Prior Art One of the more common ways to remove silaceous core material from castings has been to immerse the part in an aqueous caustic solution or a fused salt bath. Unfortunately, such treatments tended to oxidize some of the carbides that are located in the grain boundaries and in the matrix of the alloy, thereby exposing the surface to interand intragranular corrosion together with a depletion of the alloy constituents along the surface. Such corrosion markedly reduced the strength of the alloys. Also disclosed have been processes embodying the use of aqueous fluoride solutions which were effective in some controlled environments for certain types wherebyithe action of the acid on the metal can be regulated. Fluoboric acid dissolves the silica core thereby removing it from the metal casting. The process, however, can adversely affect the surface of the casting by altering its composition.
SUMMARY OF THE INVENTION In accordance with the present invention, the castings to be leached are immersed in an alkali metal carbonate solution at an elevated temperature, generally in excess of 200 F. The alkali metal carbonate solution is preferably saturated with the salt, but can be as low as w/o. Below about 25 w/o, insufficient alkali carbonate is provided to remove the silaceous core in a reasonable time. The temperature requirements are simply that the solution and the silaceous core must be sufficiently hot to leach the silaceous material in a reasonable amount of time. We have found that the solution should be above about 200 F preferably above boiling. Temperatures above 2l2 F. are realized by placing the component and the solution in a pressure vessel, commonly called an autoclave, having a heating element wrapped about the outside and arranged to raise the temperature to that which is desired. The time of the treatment is important insofar as the core is removed from the component when using the aqueous solution of alkali metal carbonate. We have found that potassium carbonate is highly desirable as the leachantbecause it effectively removes the silaceous material and does not adversely affect the surface of the component. Usually the silaceous material which forms the core is quartz or 2 fused silica and is essentially pure silica having a melting point above that of the casting.
BRIEF DESCRIPTION OF THE DRAWINGS face of superalloy castings in which cores have been removed by various solutions.
DESCRIPTION OF THE PREFERRED EMBODIMENTS In'FIG. .l, a 500X magnification of the surface. of a cobalt-base superalloy casting is shown. A core of silaceous material has been removed from the casting by dissolving it in a potassium hydroxide solution. FIG. 2 provides a 1,000X magnification of a'nickel-base superalloy casting which had the core removed by potassium hydroxide also. In both cases, it can be seen that deep fissures appear on the surface of the casting. It is believed that the potassium hydroxide not only reacts with the silaceous material of the core to dissolve it, but also reacts with carbides which were disposed near the surface of the alloy. The pockets of fissures on the surface are due to the carbides washing away because of 'the reaction with: the potassium hydroxide. In FIG. 2
there is also a depleted layer which is the result of the dissolution of alloy constituents by the leaching solution along the surface of the casting.
The rather long dark lines extending ,down from the surface of the'casting in FIGS. 1 and 2 are corrosion lines which weaken the surface of the alloy. We have also discovered that there is no effective way of removing residual alkali material when using an alkaline hydroxide as a leachant. Some alkali is entrapped in the corroded interstices or grain boundaries and on subsequent exposure to elevated temperatures in an oxidizing atmospheremore corrosion is generated.
In FIG. 3 of the drawings, a nickel-base superalloy component which has been treated according to the process of the present invention is shown at a 500x magnification. As-can be seen, neither pitting nor corrosion from the core removal treatment nor alloy depletion occurred.
As we have stated, cores from nickeland cobaltbase superalloy castings can be removed according tov the present process. Those alloys generally contain 5 to 25 w/o Cr, 5 to 15 w/o molybdenum, tantalum or tungsten, 2 to 8 w/o aluminum and titanium, less than 1 w/o carbide and the balance nickel and/or cobalt. Representative of the superalloys are those identified in the industry on the following Table I.
TABLE I 0.11 C, 4.3 Ta, 0.015 B, 0.07 Zr, balance Ni The present process can also be used with nickel-,
- specific embodiment of the present invention.
EXAMPLE 300 grams of 2were placed in a graduate and the graduate was then filled to 1,000 milliliters with water.
The contents were stirred until all of the 2was dissolved. 3-1 ,900, a nickel-based superalloy, was placed in an autoclave which was then filled with a p o r t ion of the pres/may desefibed-"samfion. The autoclave was heated to 425 F. for 12 hours. The sample was-then removed from the autoclave and washed. The silaceous material in the core had been leached and the surface was not appreciably affected.
In the following table a series of tests were performed using a 2leaching solution. 3-1 ,900 superalloy castings in various configurations, cast upon quarts cores, were used for the tests. The leaching rate is proportional to time, temperature, 2concentration and the shape of the casting.
tities of caustic hydroxides; placing a nickel-or cobalt 7 5 400-440 30 300-390 90% of core removed 8 5 415-445 30 300-400 of core removed 9 6 415-445 30 300-400 of core removed 10 6 490-520 30 650-800 of core removed 11 6 490-520 30 650-800 Core completelyv removed l2 6 420-450 30 300-390 40% ofcore removed 13 12 420-430 30 300-380 Core'completely Ev m I w removed As indicated, when the core was removed from'the casting there was no attack uponfthe surface of the alloy when using potassium carbonate solutions. The core removal is thus a function of the configuration of the casting, time, temperature, pressure, and concentration. Any of these can be modified to accomplish the removal in the shortest amount of time. V t
It is apparent that modifications and changes may be made within the spirit and scope of the present invention but it is our intention, however, only to be limited by the appended claims.
As our invention, we claim:
1. A method of removing silaceous cores from nickel or cobalt superalloy castings, the steps which comprise: forming an aqueous solution of alkali metal carbonate, said solution containing at least 25 weight percent alkali metal carbonate and being free of substantial quansuperalloy casting having a silaceous core in said solution and then heating to dissolve said core from said 1 casting. v
I 2. The process according to claim 1 wherein said alkali carbonate is potassium carbonate.
5 3. The process according to claim 1 wherein said solution is heated to above its boiling point in a pressure vessel.
Claims (2)
- 2. The process according to claim 1 wherein said alkali carbonate is potassium carbonate.
- 3. The process according to claim 1 wherein said solution is heated to above its boiling poiNt in a pressure vessel.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US10354471A | 1971-01-04 | 1971-01-04 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US3698467A true US3698467A (en) | 1972-10-17 |
Family
ID=22295758
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US103544A Expired - Lifetime US3698467A (en) | 1971-01-04 | 1971-01-04 | Method of removing silaceous cores from nickel and cobalt superalloy castings |
Country Status (1)
| Country | Link |
|---|---|
| US (1) | US3698467A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2316024A1 (en) * | 1975-06-30 | 1977-01-28 | Kohlswa Jernverks Ab | PROCESS FOR EXTRACTING SILICATE-BOUND MOLDING MATERIALS FROM A MOLD FILLED WITH CAST IRON |
| US4130157A (en) * | 1976-07-19 | 1978-12-19 | Westinghouse Electric Corp. | Silicon nitride (SI3 N4) leachable ceramic cores |
| US5226470A (en) * | 1989-11-17 | 1993-07-13 | The Boeing Company | Expendable ceramic mandrel |
| GB2266677A (en) * | 1992-05-08 | 1993-11-10 | Rolls Royce Plc | A method of leaching ceramic, eg alumina, cores from turbine blade castings |
| US20110048172A1 (en) * | 2009-08-06 | 2011-03-03 | Max Eric Schlienger | Systems and methods for leaching a material from an object |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2380284A (en) * | 1942-12-21 | 1945-07-10 | Du Pont | Method of cleaning ferrous metal articles |
| US3563711A (en) * | 1968-07-18 | 1971-02-16 | Trw Inc | Process for removal of siliceous cores from castings |
| US3617747A (en) * | 1968-09-26 | 1971-11-02 | Gen Electric | Detecting minute amounts of residual core material by means of neutron radiography |
-
1971
- 1971-01-04 US US103544A patent/US3698467A/en not_active Expired - Lifetime
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2380284A (en) * | 1942-12-21 | 1945-07-10 | Du Pont | Method of cleaning ferrous metal articles |
| US3563711A (en) * | 1968-07-18 | 1971-02-16 | Trw Inc | Process for removal of siliceous cores from castings |
| US3617747A (en) * | 1968-09-26 | 1971-11-02 | Gen Electric | Detecting minute amounts of residual core material by means of neutron radiography |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2316024A1 (en) * | 1975-06-30 | 1977-01-28 | Kohlswa Jernverks Ab | PROCESS FOR EXTRACTING SILICATE-BOUND MOLDING MATERIALS FROM A MOLD FILLED WITH CAST IRON |
| US4130157A (en) * | 1976-07-19 | 1978-12-19 | Westinghouse Electric Corp. | Silicon nitride (SI3 N4) leachable ceramic cores |
| US5226470A (en) * | 1989-11-17 | 1993-07-13 | The Boeing Company | Expendable ceramic mandrel |
| GB2266677A (en) * | 1992-05-08 | 1993-11-10 | Rolls Royce Plc | A method of leaching ceramic, eg alumina, cores from turbine blade castings |
| GB2266677B (en) * | 1992-05-08 | 1995-02-01 | Rolls Royce Plc | Improvements in or relating to the leaching of ceramic materials |
| US20110048172A1 (en) * | 2009-08-06 | 2011-03-03 | Max Eric Schlienger | Systems and methods for leaching a material from an object |
| US8409493B2 (en) | 2009-08-06 | 2013-04-02 | Rolls-Royce Corporation | Systems and methods for leaching a material from an object |
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