GB2226020A - Improvements in shell moulds - Google Patents
Improvements in shell moulds Download PDFInfo
- Publication number
- GB2226020A GB2226020A GB8829197A GB8829197A GB2226020A GB 2226020 A GB2226020 A GB 2226020A GB 8829197 A GB8829197 A GB 8829197A GB 8829197 A GB8829197 A GB 8829197A GB 2226020 A GB2226020 A GB 2226020A
- Authority
- GB
- United Kingdom
- Prior art keywords
- slurry
- particulate alumina
- alumina
- mesh
- particulate
- 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.)
- Withdrawn
Links
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 19
- 239000000203 mixture Substances 0.000 claims description 12
- 239000002002 slurry Substances 0.000 claims description 11
- 238000000034 method Methods 0.000 claims description 7
- GFQYVLUOOAAOGM-UHFFFAOYSA-N zirconium(iv) silicate Chemical compound [Zr+4].[O-][Si]([O-])([O-])[O-] GFQYVLUOOAAOGM-UHFFFAOYSA-N 0.000 claims description 7
- 238000005495 investment casting Methods 0.000 claims description 6
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 4
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical compound CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 claims description 3
- 239000000463 material Substances 0.000 claims description 2
- 239000004408 titanium dioxide Substances 0.000 claims description 2
- 101100093389 Neurospora crassa (strain ATCC 24698 / 74-OR23-1A / CBS 708.71 / DSM 1257 / FGSC 987) crp-7 gene Proteins 0.000 claims 1
- 239000000654 additive Substances 0.000 claims 1
- 230000000996 additive effect Effects 0.000 claims 1
- 239000011230 binding agent Substances 0.000 description 5
- 238000007598 dipping method Methods 0.000 description 5
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 229910000601 superalloy Inorganic materials 0.000 description 3
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000012768 molten material Substances 0.000 description 1
- 239000011819 refractory material Substances 0.000 description 1
- 239000011800 void material Substances 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
- B22C1/16—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents
- B22C1/165—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents in the manufacture of multilayered shell moulds
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Mold Materials And Core Materials (AREA)
- Molds, Cores, And Manufacturing Methods Thereof (AREA)
Description
1 1 UPROVEMENTS IN SHELL MOULDS This invention relates to moulds for use
in the investment casting process. I The investment casting process is well known. Broadly, the process comprises forming an accurate wax pattern of the part to be produced, dipping the pattern in a slurry of refractory material so as to form a mould, melting out the wax and then pouring molten material into the resulting void in the mould.
Complications have arisen, in that the metals which are cast have changed in character in order that gas turbine engines in which parts made by the process described herein are used, may be run at higher temperatures. Thus, the metals must now be of a kind which have a higher melting point than hitherto. This in turn has imposed higher stresses on the moulds, which have proved unable to constantly withstand those stresses.
The present invention seeks to provide an improved mould for use in the investment casting of high temperature superalloys.
According to the present invention, slurry from which an investment casting mould is made comprises a mixture of zirconium silicate and a first particulate alumina bound by a hydrolised ethyl silicate and covered by a further, sprinkled particulate alumina of coarser mesh than said first particulate alumina.
The invention will now be described, by way of example.
A slurry in which a wax pattern is to be dipped for the purpose of forming a hard shell mould around it, is prepared by mixing particulate zirconium silicate and particulate alumina in a suitable binder. The binder must be of the kind which will enable the mix to be self supporting about the wax pattern ie. when the mix is in the green state, which term is a term of the art.
h 2 Further, the binder must be of the kind which vaporises on heating of the slurry to dry and fuse it. One such binder is a hydrolised ethyl silicate. I After dipping a wax pattern in the mixture, further particulate alumina, the mesh size of which is much coarser than that of the mixed alumina, is sprinkled on the mix which is now In the form of a green coating on the wax pattern.
The process of alternately dipping and sprinkling may be effected for any desired number of times in order to build a desired thickness of slurry around the wax pattern.
The preferred mesh size of the particulate alumina which is used to form part of the mix, is nominally 200 mesh, whereas the preferred mesh size of the sprinkled particulate alumina is nominally 28 mesh ie. a size which as stated hereinbefore, is coarse relative to the 200 nominal mesh of the first mentioned particulate alumina.
The respective.quantities of zirconium silicate and the nominally 200 mesh particulate alumina are as follows:
Material Zirconium Silicate Weight Percentage - 70 Nominally 200 mesh alumina 70 - 40 The quantity of nominally 28 mesh, sprinkled alumina is that which is sufficient to cover the green zirconium silicate/nominally 200 mesh alumina mix which surrounds a wax pattern after the or each dipping thereof in the mix.
After completion of the dipping and sprinkling process, the green shell is baked in known manner, to drive off the binder and fuse the particulate structure.
The resulting structure -is one which has strength sufficient to withstand the high temperature stresses 1 3 which are imposed upon it when molten superalloy metal is poured into the space which has been created by evacuation of the melted wax. Further, its coefficient of expansion is the same as that of prior art shells, and so no changes need to be made, to the tooling from which the wax patterns are produced.
A further improvement in the strength of the shell can be achieved by the addition of from 0.25% to 4% by weight of titanium dioxide to the mix described hereinbefore. Such an addition improves the strength characteristics of the shell approximately by a factor of four, relative to the strength of the prior art shells. However not all of the modern superalloys bring about a need for this addition.
4 k 4
Claims (6)
- Claims: -I. A slurry with which an investment casting mould is made, comprising a mixture of zirconium silicate and a first particulate alumina bound by a hydrolised ethyl silicate and when covering a wax pattern, covered by a further, sprinkled particulate alumina of coarser mesh than said first particulate alumina.
- 2. A slurry as claimed in claim 1 wherein the mixture comprises by weight percentage, the following:7 Material Weight Percentage Zirconium Silicate - 70 First Particulate Alumina 70 - 40
- 3. A Slurry as claimed in claim 1 or claim 2 wherein said first particulate alumina is a nominal 200 mesh size., t.
- 4. A slurry as claimed in any of claims I to 3 wherein said further particulate alumina is a nominal 28 mesh size.
- 5. A slurry as claimed in any previous claim wherein said mix has an additive included, comprising 0.25 to 4% by weight of titanium dioxide.
- 6. A slurry with which an investment casting mould is made substantially as described herein.1 1 Published 1990 atThe Patent Office. State House, 6671 High Holborn. London WCIR 4TP- Further copies maybe obtained from The Patent office Sales Branch, St Mary Cray, Orpington. Kent BRS 3RD. Printed by Multiplex techniques ltd, St Mary CrP7 Ken Con 187
Priority Applications (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8829197A GB2226020A (en) | 1988-12-14 | 1988-12-14 | Improvements in shell moulds |
| FR8915241A FR2641274B1 (en) | 1988-12-14 | 1989-11-21 | IMPROVEMENTS IN SHELL MOLDS |
| DE19893939613 DE3939613A1 (en) | 1988-12-14 | 1989-11-30 | IMPROVEMENTS IN HOLLOW FORMS |
| AU46069/89A AU617903B2 (en) | 1988-12-14 | 1989-12-08 | Improvements in shell moulds |
| JP32485289A JPH02211928A (en) | 1988-12-14 | 1989-12-14 | Improvement of shell mold |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8829197A GB2226020A (en) | 1988-12-14 | 1988-12-14 | Improvements in shell moulds |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8829197D0 GB8829197D0 (en) | 1989-01-25 |
| GB2226020A true GB2226020A (en) | 1990-06-20 |
Family
ID=10648492
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8829197A Withdrawn GB2226020A (en) | 1988-12-14 | 1988-12-14 | Improvements in shell moulds |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPH02211928A (en) |
| AU (1) | AU617903B2 (en) |
| DE (1) | DE3939613A1 (en) |
| FR (1) | FR2641274B1 (en) |
| GB (1) | GB2226020A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103008549A (en) * | 2013-01-21 | 2013-04-03 | 贵州红林机械有限公司 | Method for manufacturing investment pattern shell with narrow and curved cavity of casting |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2225329B (en) * | 1988-11-21 | 1992-03-18 | Rolls Royce Plc | Shell moulds for casting metals |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL288882A (en) * | 1963-02-12 | |||
| GB1023829A (en) * | 1963-07-16 | 1966-03-23 | Monsanto Chemicals | Production of shell moulds |
| US4533394A (en) * | 1982-09-30 | 1985-08-06 | Watts Claude H | Process for manufacturing shell molds |
| JPS6146346A (en) * | 1984-08-09 | 1986-03-06 | Agency Of Ind Science & Technol | Investment shell mold used for unidirectional solidification casting of super alloy |
-
1988
- 1988-12-14 GB GB8829197A patent/GB2226020A/en not_active Withdrawn
-
1989
- 1989-11-21 FR FR8915241A patent/FR2641274B1/en not_active Expired - Fee Related
- 1989-11-30 DE DE19893939613 patent/DE3939613A1/en not_active Withdrawn
- 1989-12-08 AU AU46069/89A patent/AU617903B2/en not_active Expired - Fee Related
- 1989-12-14 JP JP32485289A patent/JPH02211928A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103008549A (en) * | 2013-01-21 | 2013-04-03 | 贵州红林机械有限公司 | Method for manufacturing investment pattern shell with narrow and curved cavity of casting |
Also Published As
| Publication number | Publication date |
|---|---|
| DE3939613A1 (en) | 1990-06-21 |
| FR2641274A1 (en) | 1990-07-06 |
| FR2641274B1 (en) | 1991-08-23 |
| GB8829197D0 (en) | 1989-01-25 |
| AU4606989A (en) | 1990-06-21 |
| AU617903B2 (en) | 1991-12-05 |
| JPH02211928A (en) | 1990-08-23 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |