CA1080428A - Calcia modified ceramic shell mold system - Google Patents
Calcia modified ceramic shell mold systemInfo
- Publication number
- CA1080428A CA1080428A CA276,716A CA276716A CA1080428A CA 1080428 A CA1080428 A CA 1080428A CA 276716 A CA276716 A CA 276716A CA 1080428 A CA1080428 A CA 1080428A
- Authority
- CA
- Canada
- Prior art keywords
- mold
- alumina
- silica
- ceramic
- binder
- 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
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C13/00—Moulding machines for making moulds or cores of particular shapes
- B22C13/08—Moulding machines for making moulds or cores of particular shapes for shell moulds or shell cores
Abstract
ABSTRACT OF THE DISCLOSURE
A ceramic shell mold system for use with superalloys and a process for making and utilizing the mold are described. The shell mold contains a colloidal silica binder with a material added which will decompose to form calcium oxide upon heating, and subsequently react with SiO2. The calcium oxide addition when reacted with these components provides cast parts with smoother surfaces and better dimensional accuracy. The mold is creep resistant and ideally suited for the production of directionally solidified articles but is not limited to these and can be used on any investment casting application.
A ceramic shell mold system for use with superalloys and a process for making and utilizing the mold are described. The shell mold contains a colloidal silica binder with a material added which will decompose to form calcium oxide upon heating, and subsequently react with SiO2. The calcium oxide addition when reacted with these components provides cast parts with smoother surfaces and better dimensional accuracy. The mold is creep resistant and ideally suited for the production of directionally solidified articles but is not limited to these and can be used on any investment casting application.
Description
2~ ~:
BACKGROUND OF THE INVENTION
Field of the Invention - This invention relates to the field of ceramic shell molds which consist of a ceramic aggregate bonded together with colloidal silica.
Such molds are used in the production of precision castings. The particular mold system described is particularly applicable to the production of directionally solidified superalloy articles.
Description of the Pr or Art - The use of shell molds in precision casting is a process known in the art.
In this process a meltable pattern having a configuration which generally corresponds with that of the desired final product is coated with a ceramic mix which is then dried.
; After drying the mold assembly is heated to remove the wax article. The coating process involves alternate repeated steps. In the first step the wax pattern is dipped in a slurry composed of fine ceramic particles in a binder, for example particulate zircon and colloidal silica. The second step is to apply coarser dry ceramic particles (termed stucco) to the wet slurry coat. After a drying step, these steps are repeated until the desired thickness is attained. Typical shell thicknesses are on the order of about .4 inch. Prior to casting the shell molds are heated to remove the wax pattern and are usually also fired at a high tempera~ure to promote bonding.
z~ ~:
Despite the general acceptance of this process in the high precision casting industry, problems still exist. Frequently it is desired to produce a cast part which needs no further production s~eps, one which is suited in size and surface ~inish for its end use.
Despite the general strength of ceramic shell mold, creep and distortion during casting is a problem and these phenomena make accurate dimensional control difficult.
Likewise, there is always some reaction between the metal ;;
and the mold, and this is reflected in an undesirably ;~
rough casting surface or in important alloying elements being depleted from the surface due to interaction with the mold material.
The problems of dimensional control and surface finish are aggravated in the casting of the complex nickel and cobalt base superalloys, many o which contain reactive elements such as Hf, Ti, Zr, Al and Ta.
Directional solidification is a technique used to produce an oriented cast grain structure in articles, and `~
is described in U. S. Patent 3,260,505 assigned to the -present assignee. The solidification process is controlled `~
; and the liquid-solid interface is constrained to move ~; along a particular axis, and the long axes of the elongated grains are found to be generally parallel to this axis.
Solidification rates must be slow if the desired grain structure is to be obtained and the total solidification time for a superalloy article such as a gas ~urbine blade -~
"~
BACKGROUND OF THE INVENTION
Field of the Invention - This invention relates to the field of ceramic shell molds which consist of a ceramic aggregate bonded together with colloidal silica.
Such molds are used in the production of precision castings. The particular mold system described is particularly applicable to the production of directionally solidified superalloy articles.
Description of the Pr or Art - The use of shell molds in precision casting is a process known in the art.
In this process a meltable pattern having a configuration which generally corresponds with that of the desired final product is coated with a ceramic mix which is then dried.
; After drying the mold assembly is heated to remove the wax article. The coating process involves alternate repeated steps. In the first step the wax pattern is dipped in a slurry composed of fine ceramic particles in a binder, for example particulate zircon and colloidal silica. The second step is to apply coarser dry ceramic particles (termed stucco) to the wet slurry coat. After a drying step, these steps are repeated until the desired thickness is attained. Typical shell thicknesses are on the order of about .4 inch. Prior to casting the shell molds are heated to remove the wax pattern and are usually also fired at a high tempera~ure to promote bonding.
z~ ~:
Despite the general acceptance of this process in the high precision casting industry, problems still exist. Frequently it is desired to produce a cast part which needs no further production s~eps, one which is suited in size and surface ~inish for its end use.
Despite the general strength of ceramic shell mold, creep and distortion during casting is a problem and these phenomena make accurate dimensional control difficult.
Likewise, there is always some reaction between the metal ;;
and the mold, and this is reflected in an undesirably ;~
rough casting surface or in important alloying elements being depleted from the surface due to interaction with the mold material.
The problems of dimensional control and surface finish are aggravated in the casting of the complex nickel and cobalt base superalloys, many o which contain reactive elements such as Hf, Ti, Zr, Al and Ta.
Directional solidification is a technique used to produce an oriented cast grain structure in articles, and `~
is described in U. S. Patent 3,260,505 assigned to the -present assignee. The solidification process is controlled `~
; and the liquid-solid interface is constrained to move ~; along a particular axis, and the long axes of the elongated grains are found to be generally parallel to this axis.
Solidification rates must be slow if the desired grain structure is to be obtained and the total solidification time for a superalloy article such as a gas ~urbine blade -~
"~
-3-Z~
may be several hours. This extended high temperature exposure aggravates both the dimensional problems and surface finish problems.
~ o references which disclose modification of the silica bonding agent to overcome these problems are known.
U. S. Patent 2,883,723, to Moore et al, discloses the addi-tion of a wide variety of chemical compounds to improve the shakeout properties of silicate bonded cores which are hardened with carbon dioxide.
In accordance with an embodiment of the invention there is provlded a method for improving the surface finish of investment cast superalloy and ferrous articles, cast in ceramic shell molds which incorporate an SiO2 binding agent, which are produced by placing multiple ceramic slurry coats and stuccos on a meltable pattern and which are fired at an elevated temperature prior to use, which comprises: adding a material to the silica based binding agent in at least the first ceramic coat which transforms to CaO, upon exposure to the mold firing temperature, in an amount sufficient to produce a CaO:SiO2 ratio of about 1:20 upon firing, - In accordance with a further embodiment, a high strength creep resistant shell mold which is essentially nonreactive with molten superalloys is formed by: a) pro-viding a meltable pattern, b) dipping the pattern in a slurry which consists of from about 15 to about 30 weight percent of a binder based on an aqueous mix which contains about 30 weight percent colloidal silica, or the equivalent thereof, from about .26 to 1.4 weight percent calcium carbonate, up to about .2 weight percent of a wetting agent, balance essentially -100 mesh ceramic aggregate, selected from the group consisting of alumina plus up to 30% of alumina-silica
may be several hours. This extended high temperature exposure aggravates both the dimensional problems and surface finish problems.
~ o references which disclose modification of the silica bonding agent to overcome these problems are known.
U. S. Patent 2,883,723, to Moore et al, discloses the addi-tion of a wide variety of chemical compounds to improve the shakeout properties of silicate bonded cores which are hardened with carbon dioxide.
In accordance with an embodiment of the invention there is provlded a method for improving the surface finish of investment cast superalloy and ferrous articles, cast in ceramic shell molds which incorporate an SiO2 binding agent, which are produced by placing multiple ceramic slurry coats and stuccos on a meltable pattern and which are fired at an elevated temperature prior to use, which comprises: adding a material to the silica based binding agent in at least the first ceramic coat which transforms to CaO, upon exposure to the mold firing temperature, in an amount sufficient to produce a CaO:SiO2 ratio of about 1:20 upon firing, - In accordance with a further embodiment, a high strength creep resistant shell mold which is essentially nonreactive with molten superalloys is formed by: a) pro-viding a meltable pattern, b) dipping the pattern in a slurry which consists of from about 15 to about 30 weight percent of a binder based on an aqueous mix which contains about 30 weight percent colloidal silica, or the equivalent thereof, from about .26 to 1.4 weight percent calcium carbonate, up to about .2 weight percent of a wetting agent, balance essentially -100 mesh ceramic aggregate, selected from the group consisting of alumina plus up to 30% of alumina-silica
- 4 -:~8~42l5 compounds, and zircon, c) applying a stucco of dry ceramic particles to the wet slurry coated surface, d~ drying the stuccoed slurry, e) repeating steps b, c and d a plurality of times, until the desired mold thickness is obtained, f) heating the pattern~mold assembly to remove the meltable pattern, g) firing the mold at a temperature at which the calcium carbonate decomposes to form to calcium oxide, which is then available to react with the silica in the binder.
The foregoing and other objects, features and ad-vantages of the present invention will become more apparent in the light of the following detailed description of the preferred embodiment thereof as shown in the accompanying drawing.
BRIEF_DESCRIPTION OF T~ DRAWI~GS
Fig. 1 shows a superalloy part cast in a calcia modified alumina shell mold made according to the present ; invention, ~-Fig. Z shows a superalloy part cast in a shell mold having a calcia modified alumina face coat and a zircon backing, Fig. 3 shows a superalloy part cast in a prior art shell molding having a calcia free alumina face coat and a calcia free zircon backing.
- 4a -~:, f~ 2~
SUMMARY OF THE INVENTION
Improved colloidal silica binding agents which incorporate a material capable o transforming to calcia are described. The calcia reacts with the colloidal silica to -Eorm a high viscosity glass-like phase which has a very low reactivity with molten superalloysO
The preferred additive to the silica binder is calcium carbonate in amounts of from about 5.8 to 15.45 weight percent of the colloidal silica present in the binder.
After decomposition of the calcium carbonate by heating, -the binder will contain from about 3 to about 8 weight percent of calcia.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention involves the discovery that if - -~
about 5 weight percent of the colloidal silica binder is replaced by calcium oxide, CaO or calcia, a greatly improved mold material results. The mold materials of the present invention have been developed and tested for `~
the investment casting of the superalloys, and are ;~
especially suited for the production of directionally solidified superalloy articles.
The binder conventionally used to produce shell molds for superalloys consists essentially of about 30 weight percent colloidal silica in an aqueous base, although of course, other colloidal silica concentra~ions may be employed within the scope of this invention. The colloidal silica remains in suspension and thoroughly mixed
The foregoing and other objects, features and ad-vantages of the present invention will become more apparent in the light of the following detailed description of the preferred embodiment thereof as shown in the accompanying drawing.
BRIEF_DESCRIPTION OF T~ DRAWI~GS
Fig. 1 shows a superalloy part cast in a calcia modified alumina shell mold made according to the present ; invention, ~-Fig. Z shows a superalloy part cast in a shell mold having a calcia modified alumina face coat and a zircon backing, Fig. 3 shows a superalloy part cast in a prior art shell molding having a calcia free alumina face coat and a calcia free zircon backing.
- 4a -~:, f~ 2~
SUMMARY OF THE INVENTION
Improved colloidal silica binding agents which incorporate a material capable o transforming to calcia are described. The calcia reacts with the colloidal silica to -Eorm a high viscosity glass-like phase which has a very low reactivity with molten superalloysO
The preferred additive to the silica binder is calcium carbonate in amounts of from about 5.8 to 15.45 weight percent of the colloidal silica present in the binder.
After decomposition of the calcium carbonate by heating, -the binder will contain from about 3 to about 8 weight percent of calcia.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention involves the discovery that if - -~
about 5 weight percent of the colloidal silica binder is replaced by calcium oxide, CaO or calcia, a greatly improved mold material results. The mold materials of the present invention have been developed and tested for `~
the investment casting of the superalloys, and are ;~
especially suited for the production of directionally solidified superalloy articles.
The binder conventionally used to produce shell molds for superalloys consists essentially of about 30 weight percent colloidal silica in an aqueous base, although of course, other colloidal silica concentra~ions may be employed within the scope of this invention. The colloidal silica remains in suspension and thoroughly mixed
-5-~ 0 ~2 8 as a result of interparticle electric charges which prevent the particles from settling out. Consequently all shell mold slurry composi~ions must be carefully formulated to avoid disrupting ~he collidal silica particle equilibria.
Such disruption can occur if the pH of the colloidal silica mix is changed.
Although the mechanism by which the present invention works is not completely understood, it is believed to involve the ~ormation of a high viscosi~y glass-like phase `-~
during the fîring/bonding step before casting which provides a smooth nonreactive surface and which also ;~ ;
promotes interparticle bonding by liquid phase sintering for improved strength.
Ceramic phase diagrams indicated that such a glass phase might form if calcium oxide were added to the silica binding agent. However, calcium oxide ionizes in water and this ionization would disrupt the colloidal silica, causing the silica to gell and harden. It was then determined that a calcium compound which did not ionize signi~icantly in water and which transformed to calcium oxide during the firing step, might be employed.
The best calcium compound appeared to be calcium carbonate (CaCo3). Upon heating at elevated temperatures the calcium carbonate reacts as shown below.
CaC03 ~ --.~ CaO ~ C02 The C02 is a gas which leaves the permeable mold and causes no problems in the casting process.
Thus the preferred shell mold binder includes colloidal -~
silica and a material which will transform to calcia upon heating. The calcia forming material is preferably present in an amount which will form an amount of calcia equal to about 3 to about 8 weight percent o~ the silica binder. In the case of calcium carbonate, approximately 1.93 parts by weight of calcium carbonate will yield 1 part by weight of calcia, and from about 5.8 to about 15.45 weight percent CaCO3 will decompose to about 3 to about 8 weight percent calcia. The calcia is preferably of high purity, containing less than abou~ 50 parts per million of alkali metal impurities,since such impurities tend to cause the formation of undesirable glassy phases.
This modified silica binder will work with several ; particulate refractory materials including zircon and alumina, but alumina is the preerred ceramic aggregate.
It is believed that where alumina is utilized as the refractory aggregate~ a CaO-SiO2-A12O3 glass-like phase occurs. Where alumina is used as the binder slurry `
aggregate, up to about 30% of alumina-silica compounds such as kyanite and mullite may also be present. It has been experimentally determined that the SiO2~CaO binder in combination with an alumina refractory yields a mold - stronger to one formed, for example using a zircon refractory material, in strength and creep resistance.
However, very often that increase in strength obtained with the zircon system may be sufficient; if improved sur~ace 1~:3B04Z8 finish is the major objective, only the silica binder in the first slurry coat need be modified with calcia.
Figures 1, 2 and 3 are macrophotographs of nickel base superalloy blades. The blades are all of the same alloy, which contained 10% Cr, 15% Co, 4.5% Ta, 5.5% Al, 3.0%
Mo, .17% C, 1% V~ 2% Hf, balance essentially nickel.
This alloy was cast at a temperature of 2800F into shell molds which had been preheated to 2700F, and directionally ;
solidified. Solidification was complete in approximately 1 hour. -`
The blade shown in Fig. 1 was cast in a calcia modi-fied alumina shell according to the preferred embodiment of this invention. The details of the mold preparation and composition are given in Table I. The blade shown in Fig. 2 was cast in a shell mold which had a calcia modiied alumina first coat (prime coat~ followed with silica bonded zircon based slurry coats and zircon s~uccos.
The details of this shell are given in Table II. The blade shown in Fig. 3 was made in a mold which had a -~
noncalcia modified alumina base coat and a zircon backing, the mold details would be identical to those set forth in Table II except that no calcium carbonate was added to the first slurry coat. These molds were fired at 1800F
prior to casting to convert the CaCO3 (where present) to ;~
CaO. "`
Comparing Fig. 2 and Fig. 3 it can be seen that a small addition of CaO to the first shell coat makes a ;~
dramatic di~ference in the amount of mold-metal reaction which occurs. The blade in Fig. 3 shows a significant amount of mold-metal reaction product on its surface, but ~he blade in Fig. 2 shows virtually none.
Careful measurement o~ the blades in Fig. 1 and Fig.
3 (alumina backup and zircon shell respectively) showed that the Fig. 1 blade ~all alumina) had undergone significantly less distortion than the Fig. 2 blade, (all zircon) and this indicates that the calcia modified alumina shell is stronger, at casting temperatures, than the zircon shell.
The preferred physical parameters of the slurries of the present invention are listed in Table III and the broad composition limits o~ the slurry coats are given in Table IV.
Although the invention has been shown and described with respect to a preferred embodiment thereof, it should be understood by those skilled in the art that various changes and omissions in the orm and detail thereof may be made therein without departing from the spirit and the scope of the invention.
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TABLE III -SLURRY PARAMETERS
FOR CALC IllM OXIDE _ODIFIED ALUMINA SHELL
Slurry Viscosity and Specific_ Gravity Ranges.
Slurry Viscosity (#4 Zahn cu~ Specific Gravi~ `
(Prime) 12-20 Seconds 2 .4 - 2 . 6 2, 3, 4 etc . 8-12 Seconds 2 . 35 - 2 . 5 (Backups) ' .,; -" ~.
~,.: :,;
-L~Z~
TABLE IV .
Slurry Composition Limits Welght Percent Colloidal silica 15~30 . ~
(30% aqueous mix~ ~ .
Calcium Carbonate* .26-1.4 -100 mesh Ceramic balance Aggregate, Alumina :
or Zircon Wetting Agent 0-1%
*containing less than about 50 ppm of alkali metal impurities ~ ~, , ~`
',.
' ~
Such disruption can occur if the pH of the colloidal silica mix is changed.
Although the mechanism by which the present invention works is not completely understood, it is believed to involve the ~ormation of a high viscosi~y glass-like phase `-~
during the fîring/bonding step before casting which provides a smooth nonreactive surface and which also ;~ ;
promotes interparticle bonding by liquid phase sintering for improved strength.
Ceramic phase diagrams indicated that such a glass phase might form if calcium oxide were added to the silica binding agent. However, calcium oxide ionizes in water and this ionization would disrupt the colloidal silica, causing the silica to gell and harden. It was then determined that a calcium compound which did not ionize signi~icantly in water and which transformed to calcium oxide during the firing step, might be employed.
The best calcium compound appeared to be calcium carbonate (CaCo3). Upon heating at elevated temperatures the calcium carbonate reacts as shown below.
CaC03 ~ --.~ CaO ~ C02 The C02 is a gas which leaves the permeable mold and causes no problems in the casting process.
Thus the preferred shell mold binder includes colloidal -~
silica and a material which will transform to calcia upon heating. The calcia forming material is preferably present in an amount which will form an amount of calcia equal to about 3 to about 8 weight percent o~ the silica binder. In the case of calcium carbonate, approximately 1.93 parts by weight of calcium carbonate will yield 1 part by weight of calcia, and from about 5.8 to about 15.45 weight percent CaCO3 will decompose to about 3 to about 8 weight percent calcia. The calcia is preferably of high purity, containing less than abou~ 50 parts per million of alkali metal impurities,since such impurities tend to cause the formation of undesirable glassy phases.
This modified silica binder will work with several ; particulate refractory materials including zircon and alumina, but alumina is the preerred ceramic aggregate.
It is believed that where alumina is utilized as the refractory aggregate~ a CaO-SiO2-A12O3 glass-like phase occurs. Where alumina is used as the binder slurry `
aggregate, up to about 30% of alumina-silica compounds such as kyanite and mullite may also be present. It has been experimentally determined that the SiO2~CaO binder in combination with an alumina refractory yields a mold - stronger to one formed, for example using a zircon refractory material, in strength and creep resistance.
However, very often that increase in strength obtained with the zircon system may be sufficient; if improved sur~ace 1~:3B04Z8 finish is the major objective, only the silica binder in the first slurry coat need be modified with calcia.
Figures 1, 2 and 3 are macrophotographs of nickel base superalloy blades. The blades are all of the same alloy, which contained 10% Cr, 15% Co, 4.5% Ta, 5.5% Al, 3.0%
Mo, .17% C, 1% V~ 2% Hf, balance essentially nickel.
This alloy was cast at a temperature of 2800F into shell molds which had been preheated to 2700F, and directionally ;
solidified. Solidification was complete in approximately 1 hour. -`
The blade shown in Fig. 1 was cast in a calcia modi-fied alumina shell according to the preferred embodiment of this invention. The details of the mold preparation and composition are given in Table I. The blade shown in Fig. 2 was cast in a shell mold which had a calcia modiied alumina first coat (prime coat~ followed with silica bonded zircon based slurry coats and zircon s~uccos.
The details of this shell are given in Table II. The blade shown in Fig. 3 was made in a mold which had a -~
noncalcia modified alumina base coat and a zircon backing, the mold details would be identical to those set forth in Table II except that no calcium carbonate was added to the first slurry coat. These molds were fired at 1800F
prior to casting to convert the CaCO3 (where present) to ;~
CaO. "`
Comparing Fig. 2 and Fig. 3 it can be seen that a small addition of CaO to the first shell coat makes a ;~
dramatic di~ference in the amount of mold-metal reaction which occurs. The blade in Fig. 3 shows a significant amount of mold-metal reaction product on its surface, but ~he blade in Fig. 2 shows virtually none.
Careful measurement o~ the blades in Fig. 1 and Fig.
3 (alumina backup and zircon shell respectively) showed that the Fig. 1 blade ~all alumina) had undergone significantly less distortion than the Fig. 2 blade, (all zircon) and this indicates that the calcia modified alumina shell is stronger, at casting temperatures, than the zircon shell.
The preferred physical parameters of the slurries of the present invention are listed in Table III and the broad composition limits o~ the slurry coats are given in Table IV.
Although the invention has been shown and described with respect to a preferred embodiment thereof, it should be understood by those skilled in the art that various changes and omissions in the orm and detail thereof may be made therein without departing from the spirit and the scope of the invention.
... ~d ' ~ c~
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e ~ rl~ e 3~ q ~ e ,~ ¢
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TABLE III -SLURRY PARAMETERS
FOR CALC IllM OXIDE _ODIFIED ALUMINA SHELL
Slurry Viscosity and Specific_ Gravity Ranges.
Slurry Viscosity (#4 Zahn cu~ Specific Gravi~ `
(Prime) 12-20 Seconds 2 .4 - 2 . 6 2, 3, 4 etc . 8-12 Seconds 2 . 35 - 2 . 5 (Backups) ' .,; -" ~.
~,.: :,;
-L~Z~
TABLE IV .
Slurry Composition Limits Welght Percent Colloidal silica 15~30 . ~
(30% aqueous mix~ ~ .
Calcium Carbonate* .26-1.4 -100 mesh Ceramic balance Aggregate, Alumina :
or Zircon Wetting Agent 0-1%
*containing less than about 50 ppm of alkali metal impurities ~ ~, , ~`
',.
' ~
Claims (8)
1. A high strength creep resistant shell mold which is essentially nonreactive with molten superalloys, formed by a. providing a meltable pattern, b. dipping the pattern in a slurry which consists of from about 15 to about 30 weight percent of a binder based on an aqueous mix which contains about 30 weight percent colloidal silica, or the equivalent thereof, from about .26 to 1.4 weight percent calcium carbonate, up to about .2 weight percent of a wetting agent, balance essentially -100 mesh ceramic aggregate, selected from the group consisting of alumina plus up to 30% of alumina-silica compounds, and zircon, c. applying a stucco of dry ceramic particles to the wet slurry coated surface, d. drying the stuccoed slurry, e. repeating steps b, c and d a plurality of times, until the desired mold thickness is obtained, f. heating the pattern/mold assembly to remove the meltable pattern, g. firing the mold at a temperature at which the calcium carbonate decomposes to form to calcium oxide, which is then available to to react with the silica in the binder.
2. A shell mold as in claim 1 wherein the ceramic aggregate in the binder is essentially alumina plus up to about 30 percent of alumina-silica compounds.
3. A shell mold as in claim l wherein the ceramic aggregate is essentially zircon.
4. A shell mold as in claim 1 wherein the stucco comprises essentially alumina.
5. A shell mold as in claim 1 wherein the stucco comprises essentially zircon.
6. A method for improving the surface finish of investment cast superalloy and ferrous articles, cast in ceramic shell molds which incorporate an SiO2 binding agent, which are produced by placing multiple ceramic slurry coats and stuccos on a meltable pattern and which are fired at an elevated temperature prior to use, which comprises:
adding a material to the silica based binding agent in at least the first ceramic coat which transforms to CaO, upon exposure to the mold firing temperature, in an amount sufficient to produce a CaO:SiO2 ratio of about 1:20 upon firing.
adding a material to the silica based binding agent in at least the first ceramic coat which transforms to CaO, upon exposure to the mold firing temperature, in an amount sufficient to produce a CaO:SiO2 ratio of about 1:20 upon firing.
7. A method as in claim 6 wherein the binder also contains a refractory aggregate based on alumina which also contains up to about 30% of compounds based on alumina and silica.
8. A method as in claim 6 wherein the binder also contains a refractory aggregate based on zircon.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US67927976A | 1976-04-22 | 1976-04-22 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1080428A true CA1080428A (en) | 1980-07-01 |
Family
ID=24726274
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA276,716A Expired CA1080428A (en) | 1976-04-22 | 1977-04-21 | Calcia modified ceramic shell mold system |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS5373419A (en) |
| BE (1) | BE853798A (en) |
| CA (1) | CA1080428A (en) |
| DE (1) | DE2716342A1 (en) |
| FR (1) | FR2348772A1 (en) |
| GB (1) | GB1577836A (en) |
| SE (1) | SE7704162L (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3143036A1 (en) * | 1981-10-30 | 1983-05-05 | Dynamit Nobel Ag, 5210 Troisdorf | "METHOD FOR PRODUCING MOLDING FOR METAL CASTING" |
| JPS62173054A (en) * | 1986-01-27 | 1987-07-29 | M C L:Kk | Casting method for hollow casting and casting core |
| JPH0675744B2 (en) * | 1988-06-13 | 1994-09-28 | ホーメット・コーポレーション | Method for manufacturing ceramic shell mold for investment casting |
| FR2666528B1 (en) * | 1990-09-12 | 1993-07-02 | Snecma | PROCESS FOR THE PREPARATION OF A FOUNDRY MOLD FROM FOAM AND CERAMIC BARBOTINES USED. |
| FR2667523B1 (en) * | 1990-10-03 | 1993-07-09 | Snecma | SOLUBLE SHELL MOLD FOR FOUNDRY AND DISPOSAL PROCESS. |
| GB9104728D0 (en) * | 1991-03-06 | 1991-04-17 | Ae Turbine Components | Casting mould |
| CN102601305B (en) * | 2012-03-26 | 2013-11-20 | 大连远东美连精工有限公司 | Investment casting method by use of entity shell making |
| CN110814287A (en) * | 2019-10-22 | 2020-02-21 | 东风精密铸造安徽有限公司 | Shell manufacturing method for composite precision casting silica sol shell |
| CN112517846B (en) * | 2020-10-23 | 2022-01-14 | 中国科学院金属研究所 | Method for reducing inclusion content of high-temperature alloy casting |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR962058A (en) * | 1950-05-31 | |||
| GB1288911A (en) * | 1968-09-11 | 1972-09-13 | ||
| GB1346557A (en) * | 1972-04-21 | 1974-02-13 | Tsnii T Mashinostroienia | Flowable self-hardening mixture for making foundry moulds and cores |
-
1977
- 1977-04-12 SE SE7704162A patent/SE7704162L/en not_active Application Discontinuation
- 1977-04-13 DE DE19772716342 patent/DE2716342A1/en not_active Withdrawn
- 1977-04-14 GB GB1553477A patent/GB1577836A/en not_active Expired
- 1977-04-14 FR FR7711202A patent/FR2348772A1/en active Pending
- 1977-04-19 JP JP4506677A patent/JPS5373419A/en active Pending
- 1977-04-21 CA CA276,716A patent/CA1080428A/en not_active Expired
- 1977-04-21 BE BE176880A patent/BE853798A/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| BE853798A (en) | 1977-08-16 |
| FR2348772A1 (en) | 1977-11-18 |
| GB1577836A (en) | 1980-10-29 |
| JPS5373419A (en) | 1978-06-29 |
| DE2716342A1 (en) | 1977-11-03 |
| SE7704162L (en) | 1977-10-23 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |