CN104399885B - Method for increasing permeability of investment cast ceramic shell - Google Patents
Method for increasing permeability of investment cast ceramic shell Download PDFInfo
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- CN104399885B CN104399885B CN201410591737.5A CN201410591737A CN104399885B CN 104399885 B CN104399885 B CN 104399885B CN 201410591737 A CN201410591737 A CN 201410591737A CN 104399885 B CN104399885 B CN 104399885B
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- carbon fiber
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C9/00—Moulds or cores; Moulding processes
- B22C9/02—Sand moulds or like moulds for shaped castings
- B22C9/04—Use of lost patterns
- B22C9/043—Removing the consumable pattern
-
- 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
- B22C1/02—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by additives for special purposes, e.g. indicators, breakdown additives
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C3/00—Selection of compositions for coating the surfaces of moulds, cores, or patterns
Abstract
The invention provides a method for increasing the permeability of an investment cast ceramic shell, and belongs to the field of investment casting. The problem of easy formation of defects of the surface of a cast member in the cast member casting process in the prior art is solved. The method comprises the following steps: adding an adhesive, strengthening layer all-layer powder and carbon-containing fibers into a stirring barrel, adding an antifoaming agent and a wetting agent, and adjusting the viscosity of the obtained coating to a required range by using deionized water to obtain a strengthening layer coating with all layers having the carbon-containing fibers; coating a wax mold with the surface layer coating of the shell according to a routine shell making technology, completing a coating, sanding and drying process by using the all-layer strengthening layer coating, coating a sealing slurry layer without the carbon-containing fibers, and drying to obtain a shell; and dewaxing the shell, and roasting to obtain the net structured ceramic shell with exhaust channels. The method guarantees the strength of the shell, improves the permeability of the shell, eliminates the defects caused by unsmooth exhaust of the surface of the cast member, guarantees the quality of the surface of the cast member, and improves the qualified rate of the cast member.
Description
Technical field
The invention belongs to model casting field, relate generally to a kind of method increasing model casting ceramic shell gas permeability.
Background technology
The increasing complex structural member and wall thickness thin-walled parts less than 1mm need to be molded using forging type, shell
Closely connected and composed by powder and sand material, almost there is no space, if in cast, shell makes moist, or gas in alloy
Too high levels, the gas in shell cannot be discharged, and will form the defect such as pore or cold shut in cast(ing) surface, cause foundry goods report
Useless.
Therefore, it is necessary to solve the problems, such as that in casting process, gas cannot be discharged from shell by technological improvement.
Content of the invention
The invention aims to solving above-mentioned the problems of the prior art, there is provided a kind of increase model casting pottery
The method of shell gas permeability.The method be by during making shell to coating in add the carbon fiber-containing such as terylene, shell processed
Afterwards fiber is eliminated by roasting, obtain the network structure ceramic shell with exhaust passage, both can ensure the intensity of shell, may be used again
To improve the gas permeability of shell, thus ensureing that the gas in foundry goods alloy or shell in casting process can be discharged, eliminate casting
The qualification rate of foundry goods, due to being vented the defect freely not caused it is ensured that the surface quality of foundry goods, is improved in part surface.
For achieving the above object, technical scheme is as follows:
A kind of method increasing model casting ceramic shell gas permeability, concrete operation step is as follows:
(1) prepare the carbon fiber-containing coating of shell
It is the powder of ground floor of back-up coat to the second layer of shell and subsequently add carbon fiber-containing in each back-up coat powder,
Last slurry seal layer powder is without carbon fiber-containing；Binding agent, back-up coat each layer powder and carbon fiber-containing will add agitator, stir
Mix speed 400-500r/min, stir 24～30 hours, add defoamer and wetting agent, and deionized water is by above-mentioned mixing
Thing viscosity is adjusted to scope needed for each coating of back-up coat, that is, obtain the reinforced layered slurry that each layer adds carbon fiber-containing；
Wherein, described carbon fiber-containing is terylene, aramid fiber etc., and addition is the 0.5-3wt% of back-up coat each layer powder quality,
Specification is diameterLength 2-5mm；
Described back-up coat powder is the refractory materials, preferably 320# such as electrofused mullite powder, electro-corundum powder or bauxite
Electrofused mullite powder and 320# electro-corundum powder；Described binding agent is Ludox, silester etc., preferably grj26 type Ludox；
Defoamer is n-butanol etc.；Wetting agent is stearic acid etc.；
The mass ratio of the described each layer powder of back-up coat and each layer binder is 3.5～4.5:1；Described defoamer addition is
0.5%～1.0wt% of each layer binder quality；Described wetting agent addition is 0.5%～1.0wt% of binding agent quality；
(2) prepare shell
Be the coating of superficial layer according to the ground floor that conventional process for making shell coats shell on wax-pattern, this coating without
After carbon fiber-containing, and stucco drying；Complete to hang painting, stucco, the mistake being dried with each layer reinforced layered slurry that step (1) is obtained again
Journey, finally coats the slurry seal coating without carbon fiber-containing again and is dried, obtain shell；Shell through dewaxing, in electric furnace or
Roasting in a conventional manner in the roasters such as gas furnace, and when 700 DEG C -800 DEG C, carbon fiber-containing is burnt by insulation 2-3 hour
Afterwards, it is further continued for being warming up to and burns temperature eventually, obtain the network structure ceramic shell with exhaust passage.
The present invention compared with prior art, it is advantageous that:
1st, add carbon fiber-containing in the coating of shell processed it is therefore an objective to form exhaust passage in shell.I.e. after roasting,
Carbon fiber-containing decomposes, and forms netted pore structure, the discharge for a small amount of gas in shell during cast provides passage, it is to avoid casting
The defects such as the pore freely not caused, pit are discharged it is ensured that the surface quality of foundry goods due to gas in part surface, improve foundry goods
Casting qualification rate.
2nd, the carbon fiber-containing adding is a diameter ofLength is 2-5mm, and fiber is relatively fine, easily uniformly
It is blended in coating, fiber will not be deposited in the bottom applying slip, and mixed process is simple；And after high-temperature roasting, type
Shell hollow gap structure is fine and closely woven, and the gas permeability that both can improve shell ensures that the intensity of shell.
3rd, this method is without carbon fiber-containing in the coating of surface in the ground floor of shell, if adding fiber can make type
Shell space becomes big, reduces shell surface smoothness, and makes foundry goods scab, causes more defects of foundry goods.
4th, this method is particularly well-suited to orientation, single crystal blade and has less wall thickness parts of Casting.
Brief description
Fig. 1 is shell schematic diagram.
Fig. 2 is section enlarged diagram after common shell shell.
Fig. 3 is to add shell section enlarged diagram after carbon fiber-containing.
Specific embodiment
Embodiment 1
Make 10 certain small-sized thin-walled workpiece, contour dimension is about 60mm × 100mm × 250mm.
By each for back-up coat layer refractory material powder 320# bauxite powder with grj26 type Ludox according to mass ratio 4-4.5:1
Ratio weigh material, together with polyster fibre add agitator in mix, mixing speed 400-500r/min, stir 24h, then plus
The defoamer n-butanol entering to account for each layer Ludox quality 0.5～1wt% and the wetting accounting for each layer Ludox quality 0.5～1wt%
Agent stearic acid, and dope viscosity is adjusted to scope needed for each coating of back-up coat by deionized water, obtains each layer and adds terylene
The reinforced layered slurry of fiber, last slurry seal coating is not added with polyster fibre；Wherein, polyster fibre adds quality is that back-up coat is each
0.5～0.7wt% of layer powder quality, fibre diameter isLength is 2-5mm；
It is surface coating according to the ground floor that conventional process for making shell coats shell on wax-pattern, superficial layer is that carbon containing is not fine
Dimension oxidation aluminium paint, and stucco be dried after, back-up coat coat again after coating 5 layers of reinforced layered slurry containing polyster fibre altogether without
The slurry seal coating slurry seal of carbon fiber-containing；Shell, after dewaxing, carries out roasting in electric furnace, and roasting technique is 300 DEG C × 1h+
500℃×1h+700℃×2h+930℃×2h.
Poured into a mould with this shell, the cast(ing) surface obtaining is smooth, eliminated gas hole defect, qualification rate 100%.
Comparative example 1
Make certain small-sized thin-walled workpiece described in 10 embodiments 1.
Will be molten with embodiment 1 ratio identical back-up coat each layer refractory material powder 320# bauxite powder and grj26 type silicon
Glue, adds mix and blend 24h in agitator, mixing speed 400-500r/min, adds and account for Ludox quality 0.5～1wt%
Defoamer n-butanol and account for the wetting agent stearic acid of Ludox quality 0.5～1wt%, and dope viscosity is adjusted by deionized water
Scope needed for whole each coating to back-up coat, that is, obtain each layer reinforced layered slurry；
It is surface coating according to the ground floor that conventional process for making shell coats shell on wax-pattern, superficial layer applies for aluminum oxide
Material, back-up coat coats slurry seal layer slurry seal again after coating 5 layers of reinforced layered slurry altogether；Shell, after dewaxing, is roasted in electric furnace
Burn, roasting technique is to be warmed up within 4 hours 930 DEG C and be incubated 2h from 300 DEG C.
Poured into a mould with this shell, the part cast(ing) surface out-of-flatness obtaining, had gas hole defect, qualification rate 60%.
Fig. 1 is conventional casting shell molds schematic diagram, if in shell or alloy during cast gas flow more it is impossible to pass through shell
Wall is discharged, and gas may build up shell inwall (outer surface of foundry goods), thus form pore or cold shut etc. in cast(ing) surface lacking
Fall into, cause foundry goods to scrap.
Fig. 2 is section enlarged diagram after comparative example 1 shell shell, and whole cross section is made up of sand material and powder, and powder is tight
Close connection, almost very close to each other.
Fig. 3 adds the shell schematic cross-section after fiber for embodiment 1 it can be seen that staying netted logical after fiber roasting
Road, different interchannels overlap in length and breadth, define the passage of gas discharge, gas is easily discharged, thus decreasing casting defect, improve
The qualification rate of foundry goods.
Embodiment 2
Make 10 certain blade parts, contour dimension is about 150mm × 50mm × 20mm.
By each for back-up coat layer refractory material powder 320# electrofused mullite powder with grj26 type Ludox according to mass ratio 3.5-
The ratio of 4:1 weighs material, and part Ludox is poured in agitator, load weighted each layer powder is divided 3～4 times and pours stirring into
In bucket, side bevelling is stirred using mixer, mixing speed 400-500r/min, and aramid fiber is blended in last batch of powder
Add agitator, add remaining Ludox mix and blend 27h, be eventually adding and account for each layer Ludox quality 0.5～1wt%'s
Defoamer n-butanol and account for the wetting agent stearic acid of each layer Ludox quality 0.5～1wt%, and deionized water is by dope viscosity
It is adjusted to scope needed for each coating of back-up coat, obtains the reinforced layered slurry that each layer adds carbon fiber-containing, last slurry seal layer applies
Material is not added with aramid fiber；Wherein, aramid fiber adds 1.3～1.5wt% that quality is back-up coat powder quality, and fibre diameter isLength is 2-5mm；
It is surface coating according to the ground floor that conventional process for making shell coats shell on wax-pattern, superficial layer is using not carbon containing
After the electro-corundum powder coating of fiber, and stucco drying, after back-up coat coats 6 layers of reinforced layered slurry containing aramid fiber altogether, then apply
System is without carbon fiber-containing slurry seal coating slurry seal；Shell, after dewaxing, carries out roasting, roasting technique is in gas furnace
300℃×1h+500℃×1h+750℃×3h+980℃×2h.
Poured into a mould with this shell, cast(ing) surface is smooth, eliminated gas hole defect and the table causing due to shell poor air permeability
Face fluorescence display problem, qualification rate 100%.
Embodiment 3
Make 4 certain large-sized annular parts, contour dimension is about
By each for back-up coat layer refractory material powder 320# electro-corundum powder with grj26 type Ludox according to 3.5-4.5:1's
Ratio weighs material, and part Ludox is poured in agitator, load weighted powder is divided 3～4 times and pours in agitator, while falling
Side is stirred using mixer, mixing speed 400-500r/min, aramid fiber is blended in last batch of powder and adds stirring
Bucket, adds remaining Ludox mix and blend 30h, is eventually adding and is just accounting for the defoamer of each layer Ludox quality 0.5～1wt%
Butanol and account for the wetting agent stearic acid of each layer Ludox quality 0.5～1wt%, and deionized water dope viscosity is adjusted to plus
Gu scope needed for each coating of layer, obtain the reinforced layered slurry that each layer adds aramid fiber, last slurry seal coating is not added with virtue
Synthetic fibre fiber；Wherein, aramid fiber adds 2.5～3wt% that quality is back-up coat powder quality, and aramid fiber is a diameter ofLength is 2-5mm；
It is surface coating according to the ground floor that conventional process for making shell coats shell on wax-pattern, superficial layer is using not carbon containing
The cobalt aluminate coating of fiber, after back-up coat coats 11 layers of reinforced layered slurry containing aramid fiber altogether, then coats without carbon fiber-containing
Slurry seal coating slurry seal；Shell, after dewaxing, carries out roasting in electric furnace, and roasting technique is 300 DEG C × 1h+500 DEG C × 1h+
800℃×3h+930℃×2h..
Poured into a mould with this shell, foundry goods eliminates pore, surface crater defect, sub-surface porosity defect reduces, qualification rate
100%.
Claims (7)
1. a kind of method increasing model casting ceramic shell gas permeability is it is characterised in that concrete operation step is as follows:
(1) prepare the carbon fiber-containing coating of shell
By binding agent, back-up coat each layer powder and carbon fiber-containing add agitator, agitated after, add defoamer and wetting
Agent, and the mixture of above-mentioned binding agent, back-up coat each layer powder, carbon fiber-containing, defoamer and wetting agent glues by deionized water
Degree is adjusted to scope needed for each coating of back-up coat, that is, obtain each coating of back-up coat that each layer adds carbon fiber-containing；
Wherein, described carbon fiber-containing is terylene, aramid fiber；
The addition of described carbon fiber-containing is the 0.5-3wt% of back-up coat each layer powder quality；
The specification of described carbon fiber-containing is diameterLength 2-5mm；
Described agitating mode is: mixing speed 400-500r/min, stirs 24～30 hours；
(2) prepare shell
The surface coating of shell is coated according to conventional process for making shell on wax-pattern, this coating is without carbon fiber-containing, and spreads
After sand is dried；Complete to hang painting, stucco, the process being dried with each coating of back-up coat that step (1) is obtained again, finally coat again not
Add the slurry seal layer of carbon fiber-containing and be dried, obtain shell；Shell passes through and dewaxes, roasting in a conventional manner in roaster,
And after 700 DEG C -800 DEG C insulation 2-3 hours, it is further continued for being warming up to and burns temperature eventually, obtain the netted knot with exhaust passage
Structure ceramic shell.
2. a kind of method increasing model casting ceramic shell gas permeability according to claim 1 is it is characterised in that step
(1) each layer powder of the back-up coat described in is electrofused mullite powder, electro-corundum powder or bauxite；Described binding agent is that silicon is molten
Glue or silester.
3. a kind of method increasing model casting ceramic shell gas permeability according to claim 1 is it is characterised in that step
(1) each layer powder of the back-up coat described in is 3.5～4.5: 1 with the mass ratio of each layer binder.
4. a kind of method increasing model casting ceramic shell gas permeability according to claim 1 is it is characterised in that step
(1) defoamer described in is n-butanol；Described wetting agent is stearic acid.
5. a kind of method increasing model casting ceramic shell gas permeability according to claim 1 is it is characterised in that step
(1) the defoamer addition described in is 0.5～1.0wt% of each layer binder quality；Described wetting agent addition is each
0.5～1.0wt% of layer binder quality.
6. a kind of method increasing model casting ceramic shell gas permeability according to claim 1 is it is characterised in that step
(2) back-up coat described in is hung and is applied the number of plies for 5～11 layers.
7. a kind of method increasing model casting ceramic shell gas permeability according to claim 1 is it is characterised in that walk
Suddenly the roaster described in (2) is electric furnace or gas furnace.
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| CN201410591737.5A CN104399885B (en) | 2014-10-28 | 2014-10-28 | Method for increasing permeability of investment cast ceramic shell |
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| US4998581A (en) * | 1988-12-16 | 1991-03-12 | Howmet Corporation | Reinforced ceramic investment casting shell mold and method of making such mold |
| CN101362184B (en) * | 2008-09-08 | 2012-06-06 | 莱芜市泰钢新材料有限责任公司 | Manufacture method of stainless steel, carbon steel precision casting surface shell |
| CN102489670B (en) * | 2011-12-13 | 2013-04-03 | 丹阳市精密合金厂有限公司 | Ceramic core for molding of support plate and preparation method thereof |
| CN102527937A (en) * | 2012-03-15 | 2012-07-04 | 哈尔滨工业大学 | Method for preparing fiber-reinforced thin-wall shell for casting titanium alloy smelting mold |
| CN103639359B (en) * | 2013-11-01 | 2018-02-16 | 南昌航空大学 | A kind of preparation method based on composite fibre enhancing precision investment casting mould case |
| CN103962506B (en) * | 2014-04-11 | 2016-04-06 | 内蒙古工业大学 | The preparation method of moltening mold castings fiber-reinforced composite silicasol case |
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