WO1999013137A1 - Apparatus for producing castings with directional and single crystal structure - Google Patents
Apparatus for producing castings with directional and single crystal structure Download PDFInfo
- Publication number
- WO1999013137A1 WO1999013137A1 PCT/US1998/019020 US9819020W WO9913137A1 WO 1999013137 A1 WO1999013137 A1 WO 1999013137A1 US 9819020 W US9819020 W US 9819020W WO 9913137 A1 WO9913137 A1 WO 9913137A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- shield
- mold
- directional
- crystal structure
- single crystal
- Prior art date
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B11/00—Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method
- C30B11/003—Heating or cooling of the melt or the crystallised material
Definitions
- the present invention relates to metal casting and can be used in producing large sized blades with directional and single crystal structure having large horizontal shoulders
- Apparatuses for casting blades by directional solidification methods include a heating zone and a cooling zone, which are separated by a horizontal shield or baffle
- a rigid baffle is used as a rule, as described in U S Patent Nos 3,680,028 and 4,763,716, UK Patent Application Nos 1 ,285,319 and 1,562,368, and EP 0589508, Patentsch ⁇ ft 4022389
- U S Patent Nos 3,680,028 and 4,763,716 UK Patent Application Nos 1 ,285,319 and 1,562,368, and EP 0589508, Patentsch ⁇ ft 4022389
- the horizontal shields or baffles create a heat barrier between the heating zone and the cooling zone in the apparatuses in order to increase the thermal gradient at the crystal growth front of the cast article (the blade) But when it is necessary to produce blades having large horizontal shoulders, the construction of said shields or baffles should correspond to the maximum size of a blade in a horizontal direction, which decreases the shielding effect and does not ensure the desired crystal structure
- the closest to the present invention is the apparatus disclosed in UK Patent Application No 1 ,303,038 being accepted as a prototype
- the prototype apparatus consists of a vacuum chamber, inside which a furnace for mold preheating is disposed. Disposed inside the furnace is a ceramic cluster of several blades being positioned on a chill plate. Placed between the cluster central part and a casting cavity is a closed shield which has the shape of a circular cavity . Said shield is produced jointly with a ceramic mold, is rigidly connected with it and assists in uniform heating of all the castings in a cluster along its height and also assists in decreasing the mutual effect of the ceramic cluster on the cooling process.
- the technical task of the present invention is to improve the structure of the casting (i.e., the absence of high and low angle grain boundaries) due to decreasing the radial component of the thermal gradient without changing the temperature axial gradient value in the course of the solidification process.
- Another aim of the invention is also to improve the yield of single crystal structure in the blade.
- the inventive apparatus comprises a vacuum chamber inside which there is positioned a mold preheating furnace with a ceramic mold and a vertical shield disposed therein, and a crystallizer (cooling zone).
- the vertical shield is made separate from the ceramic mold and is positioned concentrically to the casting's vertical axis; its lower butt end is open and faces the crystallizer.
- the shield can be made integral of thin graphitized foil having graphite bushes on the butt ends, or can be made as a row of members having projecting flanges which telescopically insert into each other. The number and the height of these members are defined constructively and are dependent on blade sizes.
- the shield is fixed on the mold upper portion or on a mold hanger.
- the shield should be made of a heat insulative material such as, but not limited to, graphitized foil, layers of graphite with felt, and composite materials based on carbon/ carbon.
- Fig. la is a schematic representation of the apparatus for casting the blades with large horizontal shoulders, and the shield being opened from the bottom, where the following parts are shown: a ceramic mold (1) for blades, a vertical shield (2), a hanger (3) for molds, a mold preheating furnace (4), furnace insulation (5), a cup for melt pouring (6) and the liquid metal crystallizer (7).
- Fig. lb shows the shield being made of the members telescopically inserting into each other.
- Fig. 2a illustrates the conventional technique for casting the blades with directional and single crystal structure.
- Fig. 2b illustrates how the cluster of the blades is cooled according to the prototype method where the shield construction prevents heating up the blades from inside of the cluster, but doesn't prevent overheating of the transition portion between the shroud and the airfoil.
- Fig. 2c illustrates the cooling scheme of a blade having large horizontal shoulders when directional solidification is performed using the liquid metal crystallizer and the inventive vertical shield.
- the apparatus works as follows: the mold 1 is surrounded by the vertical shield 2 which is opened from the bottom.
- the hanger 3 holds the mold in the preheating furnace 4 being embraced by the heat insulation 5.
- the molten superalloy is poured into the mold through the cup 6.
- the mold is immersed into the liquid metal crystallizer 7 at the predetermined rate.
- the shield can be made integral of thin graphitized foil having graphite bushes on the butt ends.
- the shield can be made as a row of members, e.g., rings telescopically inserting into each other in the course of directional solidification. As a result, the shield usage efficiency is increased and it is convenient in service.
- the seed with the desired crystallographic orientation is placed inside the mold before the molten alloy is poured into the mold.
- the vertical shield in the gap between the preheating furnace and the liquid metal coolant level serves to prevent heat losses in a radial direction and simultaneously does not allow the horizontal shoulders to receive the additional heat flow from the heater while not interrupting the coolant's influence. This helps to provide strict unidirectional axial heat removal from a solidifying casting and also enables avoiding the porosity in the transition portion between a shroud and an airfoil.
- Fig. 2a illustrates the conventional technique for casting the blades with directional and single crystal structure.
- the cooling of a cluster is effective only over the cluster's periphery but inside the article can be still heated from above.
- Fig. 2b illustrates how the cluster of the blades is cooled according to the prototype method; the shield construction prevents heating up the blades from inside of the cluster, but doesn't prevent overheating of the transition portion between a shroud and an airfoil. That is why the blade has defects in its structure.
- Fig. 2c Illustrates the cooling scheme of a blade having large horizontal shoulders when directional solidification is performed using the liquid metal crystallizer and the suggested vertical shield. The shield acts during the complete process of mold immersion, and the degree of perfection is preserved along the complete height of the structure due to the fact that the suggested apparatus provides the directional solidification without the radial component of the heat flow which has been the main reason for causing the low angle grain boundaries.
- the disclosed apparatus allows to decrease the role of the radial component of the thermal gradient in the process of directional solidification of the blades having large horizontal shoulders, to increase the degree of structural perfection along the complete height of a casting, to avoid porosity in the transition portion between a shroud and an airfoil, and to improve the yield of single crystal structure by 10-20%.
- Said vertical shield can be used in the installations with both a liquid metal crystallizer and a conventional crystallizer (a chill plate).
Abstract
Description
Claims
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP98946046A EP0972093A1 (en) | 1997-09-12 | 1998-09-14 | Apparatus for producing castings with directional and single crystal structure |
US09/331,001 US6557618B1 (en) | 1997-09-12 | 1998-09-14 | Apparatus and method for producing castings with directional and single crystal structure and the article according to the method |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
RU97115508A RU2116867C1 (en) | 1997-09-12 | 1997-09-12 | Device for production of unidirectional and single crystal ingots |
RU971155083 | 1997-09-12 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1999013137A1 true WO1999013137A1 (en) | 1999-03-18 |
Family
ID=20197234
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US1998/019020 WO1999013137A1 (en) | 1997-09-12 | 1998-09-14 | Apparatus for producing castings with directional and single crystal structure |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0972093A1 (en) |
RU (1) | RU2116867C1 (en) |
WO (1) | WO1999013137A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN103834990A (en) * | 2014-03-20 | 2014-06-04 | 北京科技大学 | Crystal selector for preparing directional solidification material and application thereof |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1303028A (en) * | 1970-11-12 | 1973-01-17 | ||
US5066223A (en) * | 1990-07-13 | 1991-11-19 | Leybold Aktiengesellschaft | Melting and casting furnace |
JPH09315882A (en) * | 1996-05-29 | 1997-12-09 | Komatsu Electron Metals Co Ltd | Device for producing semiconductor single crystal and production of semiconductor single crystal therewith |
-
1997
- 1997-09-12 RU RU97115508A patent/RU2116867C1/en active
-
1998
- 1998-09-14 EP EP98946046A patent/EP0972093A1/en not_active Withdrawn
- 1998-09-14 WO PCT/US1998/019020 patent/WO1999013137A1/en not_active Application Discontinuation
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1303028A (en) * | 1970-11-12 | 1973-01-17 | ||
US5066223A (en) * | 1990-07-13 | 1991-11-19 | Leybold Aktiengesellschaft | Melting and casting furnace |
DE4022389C2 (en) * | 1990-07-13 | 1995-06-08 | Leybold Ag | Melting and pouring furnace |
JPH09315882A (en) * | 1996-05-29 | 1997-12-09 | Komatsu Electron Metals Co Ltd | Device for producing semiconductor single crystal and production of semiconductor single crystal therewith |
Non-Patent Citations (1)
Title |
---|
PATENT ABSTRACTS OF JAPAN vol. 098, no. 004 31 March 1998 (1998-03-31) * |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN103834990A (en) * | 2014-03-20 | 2014-06-04 | 北京科技大学 | Crystal selector for preparing directional solidification material and application thereof |
CN103834990B (en) * | 2014-03-20 | 2016-06-29 | 北京科技大学 | A kind of crystal selector preparing unidirectional solidification material and application thereof |
Also Published As
Publication number | Publication date |
---|---|
EP0972093A1 (en) | 2000-01-19 |
RU2116867C1 (en) | 1998-08-10 |
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