EP0090118A1 - Ceramic mould and method of producing same - Google Patents
Ceramic mould and method of producing same Download PDFInfo
- Publication number
- EP0090118A1 EP0090118A1 EP82306346A EP82306346A EP0090118A1 EP 0090118 A1 EP0090118 A1 EP 0090118A1 EP 82306346 A EP82306346 A EP 82306346A EP 82306346 A EP82306346 A EP 82306346A EP 0090118 A1 EP0090118 A1 EP 0090118A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- mould
- ceramic
- article
- mould cavity
- metal coating
- 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.)
- Granted
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/12—Both compacting and sintering
- B22F3/1208—Containers or coating used therefor
- B22F3/1258—Container manufacturing
- B22F3/1275—Container manufacturing by coating a model and eliminating the model before consolidation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/12—Both compacting and sintering
- B22F3/1208—Containers or coating used therefor
- B22F3/1216—Container composition
- B22F3/1241—Container composition layered
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/12—Both compacting and sintering
- B22F3/1208—Containers or coating used therefor
- B22F3/1258—Container manufacturing
- B22F3/1283—Container formed as an undeformable model eliminated after consolidation
Definitions
- This invention relates to ceramic moulds and to a method of producing same.
- the ceramic mould has an interior which conforms to the desired configuration of the article to be produced.
- the cavity is filled with powdered metal, the mould is sealed, heated and then subjected to force sufficient to compact the powdered metal therein to form a dense article.
- the preferred compacting method is to place the powder filled mould at elevated temperature in an autoclave for hot isostatic pressing by the use of a gas, such as helium.
- One practice for producing moulds of this type involves making a wax pattern of the configuration of the article to be produced and then casting the ceramic around the pattern so that the interior of the ceramic conforms to the surface configuration of the pattern and thus the article to be produced. An opening is provided ih the ceramic through which upon heating the wax may be melted to expose the cavity. Thereafter the cavity is filled with powdered metal and the powder is compacted in the conventional manner as by hot isostatic compacting.
- a ceramic mould body having a mould cavity therein with the surface of the mould cavity conforming substantially to the configuration of the article to be produced.
- the mould cavity is generally somewhat "oversize" with respect to the final article to allow for shrinkage during compacting.
- An opening is provided for filling the cavity with powdered metal and thereafter sealing it prior to compacting.
- the mould cavity has a continuous metal coating covering its surface. This prevents contact between the metal powder and the ceramic material of the mould and thus acts as a barrier to prevent contamination by impurities such as oxides from entering the powder during the heating and compacting cycle.
- a preferred material for this coating is nickel or nickel-base alloys as they remain continuous during the high temperatures incident to hot compacting operations such as hot isostatic pressing.
- the alloy powders are generally superalloys, such as nickel, iron or cobalt-base alloys, and titanium-base alloys for use in high temperature applications, such as jet engine components and the like.
- the mould of the invention is also suitable for use with high speed steels and tool steels.
- the mould is segmented into at least two selectively separated parts. When separated the interior can be coated with the metal and then the parts can be joined to form the integral mould.
- a preferred method for applying the coating so that it is thin and continuous involves vapour deposition.
- Figure 1 shows two identical mould segments in cross-section identified as 10 having a ceramic body portion 12 with a mould cavity 14 conforming to the configuration of the article to be produced, which in this case is a gear wheel.
- the gear teeth 16 are defined in the interior surface of the body 12. This may be achieved by dipping a wax pattern conforming substantially to the shape of the gear wheel in a refractory slurry and then melting away the wax after drying the refractory material. Although this method is preferred, any other method may be used for producing the mould.
- the interior surfaces of the mould cavity are coated with a metal 18, as shown in Figure 2, and the segments are joined and filled with powdered metal 20.
- the mould is then sealed and compacted such as by hot isostatic compacting. Upon removal of the compacted article, the gear, designated as 22, is produced as shown in Figure 3.
- a ceramic shell was internally coated with nickel using the chemical vapour deposition (CVD) process. This involved injecting nickel carbonyl gas into the heated shell, whereupon the nickel metal was deposited by thermal decomposition of the gas onto the surface of the shell cavity. A coating was produced with certain areas left bare. The coating thickness was of the order of 0.0254 to 0.254mm (1 to lO mils).
- the shell was then processed in a normal manner to produce a powder metallurgy part, using a conventional nickel-base superalloy powder (Rene 95). The resulting compact was normal with an unusually bright surface appearance.
- Metallographic examination revealed a nickel surface coating, a boundary layer of interdiffusion products, and the Rene 95 base metal (see Figure 4).
- the Rene 95 powder particles are outlined by a contamination layer, a normal phenomenon with the conventional ceramic mould process (see Figure 5)-.
- the nickel coating is thus seen to provide protection from contamination for the Rene 95 base metal from which the final compacted superalloy is to be made.
- a ceramic shell was split and the interior of the shell conforming to the powdermetallurgy article to be produced was coated with nickel by the ion deposition process wherein metal atoms are directly deposited on the target surface in a vacuum chamber.
- the coating thickness was of the order of 0.00254mm (.1 mils).
- the shell was then processed in a normal manner to produce a powder metallurgy part, using titanium alloy powder. This included filling the shell with titanium alloy powder, evacuating, heating and hot-isostatic pressing to compact the powder to full density. The resulting compact had an unusually smooth surface appearance.
- Metallographic examination revealed a surface diffusion- products layer of the order of 0.00254mm (.1 mil.) thick (see Figure 6).
- a metal coating may be produced on the interior surfaces of a ceramic shell such as by electroplating the metal coating, which may be nickel, on a wax pattern shape and then providing a ceramic shell around this metal-coated wax pattern, as by dipping the assembly in a refractory slurry.
- the metal coating which may be nickel
- a wax pattern may be coated with nickel by first spraying the surface of the pattern with graphite to provide an electrically conductive base and then electroplating onto this conductive base a metal such as nickel.
Landscapes
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Mechanical Engineering (AREA)
- Powder Metallurgy (AREA)
- Moulds, Cores, Or Mandrels (AREA)
- Compositions Of Oxide Ceramics (AREA)
Abstract
Description
- This invention relates to ceramic moulds and to a method of producing same.
- It is known to produce powder metallurgy shapes of various configurations by the use of a ceramic shell- type mould. The ceramic mould has an interior which conforms to the desired configuration of the article to be produced. The cavity is filled with powdered metal, the mould is sealed, heated and then subjected to force sufficient to compact the powdered metal therein to form a dense article. The preferred compacting method is to place the powder filled mould at elevated temperature in an autoclave for hot isostatic pressing by the use of a gas, such as helium.
- One practice for producing moulds of this type involves making a wax pattern of the configuration of the article to be produced and then casting the ceramic around the pattern so that the interior of the ceramic conforms to the surface configuration of the pattern and thus the article to be produced. An opening is provided ih the ceramic through which upon heating the wax may be melted to expose the cavity. Thereafter the cavity is filled with powdered metal and the powder is compacted in the conventional manner as by hot isostatic compacting.
- In operations of this type, during heating of the powder within the ceramic mould the powder tends to become contaminated by the ceramic with which it is in contact within the mould cavity. Particles of the ceramic, including oxides, enter the powder and during compacting are confined within the densified article. These nonmetallic substances weaken the article such as by providing sites for crack propogation. In addition, reaction products, which may be from the ceramic, chemically react with powder metal to form nonmetallic compounds at prior particle boundaries after compacting.
- It is accordingly a primary object of the present invention to provide a ceramic mould adapted for use in producing powder metallurgy articles of intricate configuration that avoids contamination of the metal article by contact with the ceramic material.
- Broadly, according to the present invention there is provided a ceramic mould body having a mould cavity therein with the surface of the mould cavity conforming substantially to the configuration of the article to be produced. The mould cavity is generally somewhat "oversize" with respect to the final article to allow for shrinkage during compacting. An opening is provided for filling the cavity with powdered metal and thereafter sealing it prior to compacting. In accordance with the invention the mould cavity has a continuous metal coating covering its surface. This prevents contact between the metal powder and the ceramic material of the mould and thus acts as a barrier to prevent contamination by impurities such as oxides from entering the powder during the heating and compacting cycle. A preferred material for this coating is nickel or nickel-base alloys as they remain continuous during the high temperatures incident to hot compacting operations such as hot isostatic pressing. In accordance with the invention, the alloy powders are generally superalloys, such as nickel, iron or cobalt-base alloys, and titanium-base alloys for use in high temperature applications, such as jet engine components and the like. However, the mould of the invention is also suitable for use with high speed steels and tool steels. Preferably, to facilitate coating of the mould cavity surface the mould is segmented into at least two selectively separated parts. When separated the interior can be coated with the metal and then the parts can be joined to form the integral mould. A preferred method for applying the coating so that it is thin and continuous involves vapour deposition.
- It is known to produce powder metallurgy articles that have, after compacting, internal passages. This is conventionally achieved by providing within the mould a ceramic core or mandrel having an exterior configuration conforming to that of the internal passage desired to be produced in the final compacted article. The powder fills the mould and surrounds the mandrel. During compacting, the powder is compacted against the mandrel, and upon removal of the mandrel after compacting an internal passage is produced within the compacted article. To produce an article with an internal passage, in accordance with the present invention, the exterior of the core or mandrel is coated with metal to prevent contamination of the powder.
- The invention will be more particularly described with reference to the accompanying drawings, in which:-
- Figure 1 is a cross-section of one embodiment of a mould according to the present invention,
- Figure 2 is a cross-section of the mould of Figure 1 having the mould cavity filled with metal powder and being ready for compacting;
- Figure 3 is an elevation of a powder metallurgy product resulting from compacting using the mould of Figures 1 and 2; and
- Figures 4, 5 and 6 are photomicrographs at a magnification of 150x showing compacted alloys produced by the use of conventional ceramic moulds and moulds according to the present invention.
- With respect to the drawings, Figure 1 shows two identical mould segments in cross-section identified as 10 having a
ceramic body portion 12 with a mould cavity 14 conforming to the configuration of the article to be produced, which in this case is a gear wheel. Thegear teeth 16 are defined in the interior surface of thebody 12. This may be achieved by dipping a wax pattern conforming substantially to the shape of the gear wheel in a refractory slurry and then melting away the wax after drying the refractory material. Although this method is preferred, any other method may be used for producing the mould. The interior surfaces of the mould cavity are coated with ametal 18, as shown in Figure 2, and the segments are joined and filled with powderedmetal 20. The mould is then sealed and compacted such as by hot isostatic compacting. Upon removal of the compacted article, the gear, designated as 22, is produced as shown in Figure 3. - Although the terms "metal", "nickel" and "titanium" are used herein it is to be understood that these include alloys as well as metal in elemental form.
- The following specific examples are illustrative of the present invention:
- A ceramic shell was internally coated with nickel using the chemical vapour deposition (CVD) process. This involved injecting nickel carbonyl gas into the heated shell, whereupon the nickel metal was deposited by thermal decomposition of the gas onto the surface of the shell cavity. A coating was produced with certain areas left bare. The coating thickness was of the order of 0.0254 to 0.254mm (1 to lO mils). The shell was then processed in a normal manner to produce a powder metallurgy part, using a conventional nickel-base superalloy powder (Rene 95). The resulting compact was normal with an unusually bright surface appearance. Metallographic examination revealed a nickel surface coating, a boundary layer of interdiffusion products, and the Rene 95 base metal (see Figure 4). In an area unprotected by the nickel coating, the Rene 95 powder particles are outlined by a contamination layer, a normal phenomenon with the conventional ceramic mould process (see Figure 5)-. The nickel coating is thus seen to provide protection from contamination for the Rene 95 base metal from which the final compacted superalloy is to be made.
- A ceramic shell was split and the interior of the shell conforming to the powdermetallurgy article to be produced was coated with nickel by the ion deposition process wherein metal atoms are directly deposited on the target surface in a vacuum chamber. The coating thickness was of the order of 0.00254mm (.1 mils). The shell was then processed in a normal manner to produce a powder metallurgy part, using titanium alloy powder. This included filling the shell with titanium alloy powder, evacuating, heating and hot-isostatic pressing to compact the powder to full density. The resulting compact had an unusually smooth surface appearance. Metallographic examination revealed a surface diffusion- products layer of the order of 0.00254mm (.1 mil.) thick (see Figure 6).
- In addition to the metal coating techniques demonstrated in the specific examples, a metal coating may be produced on the interior surfaces of a ceramic shell such as by electroplating the metal coating, which may be nickel, on a wax pattern shape and then providing a ceramic shell around this metal-coated wax pattern, as by dipping the assembly in a refractory slurry. When the wax is removed by melting followed by chemical cleaning the metal layer remains bonded to the ceramic shell to produce the desired shell mould with a metal coated interior. A wax pattern may be coated with nickel by first spraying the surface of the pattern with graphite to provide an electrically conductive base and then electroplating onto this conductive base a metal such as nickel.
Claims (10)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AT82306346T ATE18364T1 (en) | 1982-03-26 | 1982-11-30 | POTTERY MOLD AND METHOD OF MAKING THE SAME. |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US36234182A | 1982-03-26 | 1982-03-26 | |
US362341 | 1982-03-26 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0090118A1 true EP0090118A1 (en) | 1983-10-05 |
EP0090118B1 EP0090118B1 (en) | 1986-03-05 |
Family
ID=23425705
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP82306346A Expired EP0090118B1 (en) | 1982-03-26 | 1982-11-30 | Ceramic mould and method of producing same |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP0090118B1 (en) |
AT (1) | ATE18364T1 (en) |
CA (1) | CA1203659A (en) |
DE (1) | DE3269719D1 (en) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4772450A (en) * | 1984-07-25 | 1988-09-20 | Trw Inc. | Methods of forming powdered metal articles |
WO1998047833A2 (en) * | 1997-04-21 | 1998-10-29 | Vawter Paul D | Method for manufacturing powder metallurgical tooling |
US6939508B2 (en) * | 2002-10-24 | 2005-09-06 | The Boeing Company | Method of manufacturing net-shaped bimetallic parts |
WO2008059272A3 (en) * | 2006-11-18 | 2009-01-15 | Bentley Motors Ltd | Ceramic tool having a material applied to the surface |
EP3391982A3 (en) * | 2017-04-21 | 2019-02-27 | Mikro Systems Inc. | Systems, devices and methods for spark plasma sintering |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE10223371A1 (en) * | 2002-05-25 | 2003-12-04 | Peter Amborn | Mold for the production of metallic moldings by casting, hot, warm o. Cold Forming and a method for producing such a mold |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE1908796A1 (en) * | 1968-02-21 | 1969-09-18 | Inst Odlewnictwa | Durable, ceramic protective coating for metal foundry molds |
DE1446181B1 (en) * | 1961-05-01 | 1970-07-16 | Internat Nickel Company Of Can | Process for coating ceramic or metal particles with a metal and reaction vessel to carry out the process |
-
1982
- 1982-11-17 CA CA000415796A patent/CA1203659A/en not_active Expired
- 1982-11-30 EP EP82306346A patent/EP0090118B1/en not_active Expired
- 1982-11-30 DE DE8282306346T patent/DE3269719D1/en not_active Expired
- 1982-11-30 AT AT82306346T patent/ATE18364T1/en not_active IP Right Cessation
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE1446181B1 (en) * | 1961-05-01 | 1970-07-16 | Internat Nickel Company Of Can | Process for coating ceramic or metal particles with a metal and reaction vessel to carry out the process |
DE1908796A1 (en) * | 1968-02-21 | 1969-09-18 | Inst Odlewnictwa | Durable, ceramic protective coating for metal foundry molds |
Non-Patent Citations (1)
Title |
---|
Chemical Abstracts vol. 90, 16 April - 30 April 1979, Columbus, Ohio, USA G. HEINICKE et al. "Tribochemical preparation of nickel carbonyl and use of carbonyl nickel in production of precision molds" Page 138, column 2, abstract no. 123943a * |
Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4772450A (en) * | 1984-07-25 | 1988-09-20 | Trw Inc. | Methods of forming powdered metal articles |
WO1998047833A2 (en) * | 1997-04-21 | 1998-10-29 | Vawter Paul D | Method for manufacturing powder metallurgical tooling |
WO1998047833A3 (en) * | 1997-04-21 | 1999-03-04 | Paul D Vawter | Method for manufacturing powder metallurgical tooling |
US6939508B2 (en) * | 2002-10-24 | 2005-09-06 | The Boeing Company | Method of manufacturing net-shaped bimetallic parts |
WO2008059272A3 (en) * | 2006-11-18 | 2009-01-15 | Bentley Motors Ltd | Ceramic tool having a material applied to the surface |
JP2010510153A (en) * | 2006-11-18 | 2010-04-02 | ベントレー モーターズ リミテッド | Improvement of ceramic tools and improvements related to ceramic tools |
EP3391982A3 (en) * | 2017-04-21 | 2019-02-27 | Mikro Systems Inc. | Systems, devices and methods for spark plasma sintering |
US11229950B2 (en) | 2017-04-21 | 2022-01-25 | Raytheon Technologies Corporation | Systems, devices and methods for spark plasma sintering |
EP4039392A1 (en) * | 2017-04-21 | 2022-08-10 | Raytheon Technologies Corporation | Systems, devices and methods for spark plasma sintering |
Also Published As
Publication number | Publication date |
---|---|
CA1203659A (en) | 1986-04-29 |
ATE18364T1 (en) | 1986-03-15 |
DE3269719D1 (en) | 1986-04-10 |
EP0090118B1 (en) | 1986-03-05 |
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