CN105367105B - The method that machining auxiliary CVI prepares thicker-walled ceramic based composites - Google Patents
The method that machining auxiliary CVI prepares thicker-walled ceramic based composites Download PDFInfo
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- CN105367105B CN105367105B CN201510847283.8A CN201510847283A CN105367105B CN 105367105 B CN105367105 B CN 105367105B CN 201510847283 A CN201510847283 A CN 201510847283A CN 105367105 B CN105367105 B CN 105367105B
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Abstract
Auxiliary CVI methods are machined the present invention relates to one kind and prepare ceramic matric composite heavy section casting (>=5mm), are comprised the following steps：Precast body is subjected to boundary layer deposition in graphite furnace；Densification is carried out to precast body by chemical vapor infiltration, precast body relative density is taken out after reaching 20%~65%；Capillary processing is carried out to precast body using the method for machining, so as to dredge the transmission channel of gaseous state precursor；Cyclic deposition, obtain ceramic matric composite.The advantages of technique：(1) pore structure of precast body in itself is improved, reduces the density gradient of composite, solve thes problems, such as ceramic matric composite heavy section casting (>=5mm) consistency inequality；(2) composite overall mechanical properties are improved；(3) densification rate is improved, shortens manufacturing cycle.
Description
Technical field
The invention belongs to the CVI preparation fields of ceramic matric composite, and in particular to prepared by one kind machining auxiliary CVI
The method of thicker-walled ceramic based composites, be in traditional chemical vapor infiltration (CVI) process, it is small using being machined
Gaseous state precursor diffusion admittance inside hole increase precast body, is internally formed porous body：Beam inside aperture, interfascicular hole and processing
The multiple dimensioned mass transfer channel of hole, so as to improve the compactness and density uniformity of ceramic matric composite heavy section casting (>=5mm),
It is prepared by the high density and high intensity for realizing ceramic matric composite.
Background technology
Ceramic matric composite can meet less than 1650 DEG C long-lives, less than 20000 DEG C finite lifetimes, less than 2800 DEG C
The requirement in instantaneous life-span, not only starts in high thrust-weight ratio aero-engine, satellite attitude control engine, hypersonic punching press
The weaponry fields such as machine, empty day round heat-protection system, cruise missile engine, liquid and solid propellant rocket have wide
Popularizing application prospect, there is very big market potential in the civil area such as turbine gas-fired station and nuclear power reactor.
Chemical vapor infiltration (CVI) method is the manufacture method of the unique commercializations of currently manufactured complicated knitted body toughness reinforcing CMC,
Its adaptability is very strong, is applied to all inorganic non-metallic materials in principle.This method can avoid high temperature from being damaged to caused by fiber
Wound, is easy to manufacture large-scale, thin-walled, the nearly end form component of complexity.But for heavy section casting product (wall thickness >=5mm), due to the work
Mass transfer of the gaseous state precursor in porous body relies primarily on diffusion in process so that is deposited in component along gas diffusion direction
In certain density gradient, cause the hole closing too early of component surface and cut off source of the gas to precast body internal transmission, cause to
" bottleneck effect " that inner void mass transfer channel blocks, so that precast body has more than 30% residual porosity, form typical case
Hollow interlayer structure, have a strong impact on the mechanical property and engineer applied of composite.How composite is improved as far as possible
Consistency, the sedimentation rate of matrix and the density gradient for reducing material internal, turn into and prepare CMC-SiC composites, particularly wall
It is badly in need of one of key issue of solution in thickness >=5mm composite research and development applications.
In order to solve the above problems, in United States Patent (USP) US5411763, it is compound that loose structure is prepared using thermal gradient CVI methods
During material, the uniformity of densification can be effectively improved, but gas transport is slow, densifying materials speed improves limited.The U.S.
Patent US5900297 discloses a kind of method that pressure gradient CVI method prepares composite material having porous structure, utilizes barometric gradient
CVI technologies, can effectively complete the densification process of material in a short period of time, but requirement of this method to equipment it is higher,
Operation difficulty is larger, is not suitable for producing in enormous quantities.In United States Patent (USP) 4580524, ceramic base composite wood is prepared using FCVI methods
Material, effectively shorten densification process, improve density uniformity, but the heating in each region depends on heat transfer in precast body
Effect, cause precast body huyashi-chuuka (cold chinese-style noodles) densification deficiency.In German patent DE 4142261, prepared using isothermal pressure gradient CVI techniques
Composite material having porous structure, effectively improves the transmittability of gas, but still suffers from the problem of densification is uneven.Document
“Microwave Heated Chemical Vapor Infiltration:Densification Mechanism of
SiCf/SiC Composites.David Jaglin,Jon Binner,and Bala Vaidhyanathan.The
American Ceramic Society,2006,9:2710-2717 " proposes is densified SiC using microwave thermal solutionf/SiC
Composite, the process can make composite average density reach 50% in 24 hours, composite central dense
Degree reaches 73%, accelerates the density speed of precast body, improves density uniformity, but the technique is higher to equipment requirement, at present
Still in the experimental stage.
The content of the invention
Technical problems to be solved
In order to avoid the shortcomings of the prior art, the present invention proposes that a kind of machining auxiliary CVI prepares thicker-walled ceramic
The method of based composites, there is provided a kind of technique is simple, cost is cheap and can effectively reduce ceramic matric composite (wall thickness >=
Density gradient 5mm), improve the chemical vapor infiltration preparation method of its compactness and mechanical property.
Technical scheme
A kind of method for being machined auxiliary CVI and preparing thicker-walled ceramic based composites, it is characterised in that step is as follows：
Step 1：Heavy wall reinforcing fiber precast body after shaping is placed in chemical vapor infiltration poke, prepared using CVI methods
Ceramic interfacial layers；
Step 2：Ceramic matrix is deposited by chemical vapor infiltration densification is carried out to fiber preform, relatively
Density reaches 35%~65%；
Step 3：Uniform machining small on fiber preform, the aperture of pitch-row >=2 times；The gaseous state increased inside precast body is first
Drive body diffusion admittance；
Step 4：The composite after processing is further densified using chemical vapor infiltration depositing base, phase
More than 90% is reached to density.
Aperture is in the step 3：The square hole or profile size that circular hole that aperture is 0.5~5mm, the length of side are 0.5~5mm
For the aperture of 0.5~5mm other shapes.
The machining holes method of the aperture is：Drilling, fraising, Che Kong, bore hole, Water Cutting hole or wire cutting hole.
The heavy wall reinforcing fiber precursor structure is：1 dimension, 2 dimensions, 2.5 dimensions or 3-dimensional.
The prefabricated preparation of heavy wall reinforcing fiber is：Lamination, braiding or acupuncture.
The fiber is high-temperature ceramic fibre.
The fiber is：Boron fibre, silicon carbide fibre or oxide fibre.
The ceramic interfacial layers are pyrolytic carbon or boron nitride.
Heavy wall >=5mm of the heavy wall reinforcing fiber precast body.
Beneficial effect
A kind of method for being machined auxiliary CVI and preparing thicker-walled ceramic based composites proposed by the present invention, is a kind of machine
Tool processes Assisted Chemical Vapor osmosis.Precast body relative density is set to reach 30% in chemical vapor infiltration deposition SiC matrix
When~70%, small hole machined is carried out to ceramic matric composite (wall thickness >=5mm) using machining equipment, made inside precast body
Formed：Beam inside aperture, interfascicular hole and the multiple dimensioned mass transfer channel for processing hole, so as to adjust the hole knot of precast body in itself
Structure, the transmission channel of gaseous state precursor is dredged, densification deposition then is carried out to precast body, until density is more than 2.0kg/cm3,
Specific steps are as schemed shown in (1)：
The beneficial effects of the invention are as follows：When preparing ceramic matric composite (wall thickness >=5mm), intervention machining aperture
Technique, help to form multiple dimensioned mass transferring in gas phase passage in deposition process, improve fibre bundle diffusion inside environment, fill by
Hole caused by CVI bottleneck techniques, reduce the density gradient of precast body, improve composite compactness, improve composite
Obdurability.Compared with prior art C/SiC composites, composite bending strength prepared by this kind of process on
Rise as shown in Figure 4.When mechanical tapping density is 1.69%, it is 2.1~2.3g/cm to prepare gained composite density3, at room temperature
Bending strength is 330~400MPa；When mechanical tapping density is 3.38%, it is 2.0~2.2g/ to prepare gained composite density
cm3, bending strength is 340~420MPa at room temperature.
Brief description of the drawings
Fig. 1：The flow chart of the inventive method
Fig. 2：It is machined micro hole aperture and layout viewing
Fig. 3：Be machined micro hole hole between, the SEM patterns on hole side
Fig. 4：The bending strength figure of composite prepared by embodiment
Embodiment
In conjunction with embodiment, accompanying drawing, the invention will be further described：
Technical solution of the present invention：Chemical vapor infiltration deposition SiC matrix make precast body relative density reach 30%~
When 70%, small hole machined is carried out to ceramic matric composite (wall thickness >=5mm) using machining equipment, makes shape inside precast body
Into：Beam inside aperture, interfascicular hole and the multiple dimensioned mass transfer channel for processing hole, so as to adjust the pore structure of precast body in itself,
The transmission channel of gaseous state precursor is dredged, densification deposition then is carried out to precast body, until density is more than 2.0kg/cm3。
Step 1, the preparation of fiber preform：After 1K carbon fibers two dimension successively lamination, to suture distance 3mm × 3mm edges
Thickness direction punctures reinforcing fiber, obtains the carbon fiber precast body that volume fraction is about 40~42%.
Step 2, chemical vapor infiltration deposition pyrolysis carbon boundary layer：Carbon fiber preform is placed in vacuum high temperature furnace,
800~1000 DEG C of depositing temperature, atmosphere pressures 0.2KPa, Ar flow 300ml/min, propylene flow 30ml/min, deposition 45~
Temperature fall after 60h.
Step 3, chemical vapor infiltration deposition SiC matrix：1000~1100 DEG C of deposition, atmosphere pressures 2KPa, Ar flow
300ml/min, H2Flow 200ml/min, MTS is brought into high temperature deposition stove by way of bubbling, H2With MTS mole matter
Amount is than being 10:1, Temperature fall after 180~230h is deposited, forms C/SiC composites.
Step 4, be machined between micro hole aperture and layout viewing 2 and its hole, the SEM patterns on hole side it is as shown in Figure 3：Perforate
A diameter of 0.5~3mm, mechanical hole are evenly distributed on the perforate face of material, the aperture of pitch-row >=2 times, perforate density be 1~
8%.
Step 5, densification is carried out to C/SiC composites using chemical vapor infiltration, until C/SiC composite woods
Material density is more than 2.0kg/cm3。
Embodiment 1：
Step 1, the two-dimension laminate carbon cloth precast body of two heats is prepared, detailed process is：
(1) T300-1K carbon fibers are selected, are made into two-dimentional plain, fold 77 layers after, use 1K carbon fibers with suture away from
Connected from the acupuncture of 3mm × 3mm through-thickness, lamination is stitched together, is 0.70g/cm so as to obtain bulk density3, carbon
Fiber volume fraction is 40.0%~42.0% carbon fiber precast body.
(2) carbon fiber precast body is clamped with graphite jig, is placed in vacuum drying oven and removing glue and pre- is carried out at 1800 DEG C
3h is handled, then by gained fiber preform using CVI deposition pyrolysis carbon boundary layers (PyC).The preparation technology of PyC interfaces phase is such as
Under：900 DEG C, atmosphere pressures 0.2KPa of depositing temperature, propylene flow 30ml/min, Ar flow 300ml/min, deposit 50~60h
Temperature fall afterwards.As above technique 2 times repeatedly.
(3) by the C/SiC composites after heat treatment using CVI methods deposition SiC matrix.Carbon fiber preform is placed in
In vacuum high temperature furnace, the specific preparation technology of SiC matrix phase is as follows：1100 DEG C of deposition, atmosphere pressures 2KPa, H2Flow 200ml/
Min, Ar flow 300ml/min, are brought MTS in high temperature deposition stove into by way of bubbling, H2Molal weight ratio with MTS is
10:1, Temperature fall after 200~230h is deposited, as above technique 4 times repeatedly, disengages graphite jig, finally giving bulk density is
1.8g/cm3C/SiC composites.
(4) it is machined aperture.C/SiC composites are removed into surface dirt in alcohol-pickled lower ultrasonic cleaning 15min
The impurity such as greasy dirt, are finally dried with baking oven, and C/SiC samples are made.Sample is placed on processing platform, from suitable
Drill bit, clamp drill bit, adjustment machining cutting speed, table position and height, centre drill bore guide hole and to sample successively
Processing, prepares the circular hole that 0.5~5mm is uniformly processed on fiber preform, the aperture of pitch-row >=2 times, and aperture perforate density is
1.69%；
(5) step (3) process is repeated densification is carried out to C/SiC composites, until sample density
For 2.0kg/cm3More than.
(6) the C/SiC composite volumes density prepared by the present embodiment is 2.2g/cm3, by SANSCMT4304 electricity
Sub- universal testing machine test, bending strength 345MPa.
Embodiment 2：
Step 1, the two-dimension laminate carbon cloth precast body of two heats is prepared, detailed process is：
(1) T300-1K carbon fibers are selected, two-dimentional plain is made into, after 77 layers of superposition, uses 1K carbon fibers to suture
The acupuncture of distance 3mm × 3mm through-thickness is connected, and lamination is stitched together, is 0.70g/cm so as to obtain bulk density3、
Carbon fibrous body fraction is 40.0%~42.0% carbon fiber precast body.
(2) carbon fiber precast body is clamped with graphite fixture, is placed in vacuum drying oven and removing glue and pre- place are carried out at 1800 DEG C
3h is managed, then by gained fiber preform using CVI depositions PyC.The preparation technology of PyC interfaces phase is as follows：920 DEG C of depositing temperature,
Atmosphere pressures 0.23KPa, propylene flow 32ml/min, Ar flow 310ml/min, deposit Temperature fall after 50~60h.As above work
Skill 2 times repeatedly.
(3) by the C/SiC composites after heat treatment using CVI methods deposition SiC matrix.Carbon fiber preform is placed in
In vacuum high temperature furnace, the specific preparation technology of SiC matrix phase is as follows：1200 DEG C of deposition, atmosphere pressures 2.2KPa, H2Flow
210ml/min, Ar flow 305ml/min, are brought MTS in high temperature deposition stove into by way of bubbling, H2With MTS mole matter
Amount is than being 10:1, Temperature fall after 200~230h is deposited, as above technique 4 times repeatedly, it is 1.7g/cm to finally give bulk density3
C/SiC composites.
(4) it is machined aperture.C/SiC composites are removed into surface dirt in alcohol-pickled lower ultrasonic cleaning 15min
The impurity such as greasy dirt, are finally dried with baking oven, and C/SiC samples are made.Sample is placed on processing platform, from suitable
Drill bit, clamp drill bit, adjustment machining cutting speed, table position and height, centre drill bore guide hole and to sample successively
Processing, it is close for 0.5~5mm square hole, the aperture of pitch-row >=2 times, aperture perforate to prepare the uniform processing length of side on fiber preform
Spend for 1.69%.
(5) step (3) process is repeated densification is carried out to C/SiC composites, until sample density
For 2.0kg/cm3More than.
C/SiC composite volumes density prepared by the present embodiment is 2.1g/cm3, by SANSCMT4304 electronics ten thousand
Energy experimental machine test, bending strength 330MPa.
Claims (1)
- A kind of 1. method for being machined auxiliary CVI and preparing thicker-walled ceramic based composites, it is characterised in that step is as follows：Step 1：Heavy wall reinforcing fiber precast body after shaping is placed in chemical vapor infiltration poke, ceramics are prepared using CVI methods Boundary layer；Step 2：Ceramic matrix is deposited by chemical vapor infiltration densification is carried out to fiber preform, relative density reaches To 35%~65%；Step 3：Uniform machining small on fiber preform, the aperture of pitch-row >=2 times；Increase the gaseous state precursor inside precast body Diffusion admittance；Step 4：The composite after processing is further densified using chemical vapor infiltration depositing base, it is relatively close Degree reaches more than 90%；Aperture is in the step 3：The square hole or profile size that circular hole that aperture is 0.5~5mm, the length of side are 0.5~5mm be The aperture of 0.5~5mm other shapes；The machining holes method of the aperture is：Drilling, fraising, Che Kong, bore hole, Water Cutting hole or wire cutting hole；The heavy wall reinforcing fiber precursor structure is：1 dimension, 2 dimensions, 2.5 dimensions or 3-dimensional；The prefabricated preparation of heavy wall reinforcing fiber is：Lamination, braiding or acupuncture；The fiber is high-temperature ceramic fibre；The fiber is：Boron fibre, silicon carbide fibre or oxide fibre；The ceramic interfacial layers are pyrolytic carbon or boron nitride；Heavy wall >=5mm of the heavy wall reinforcing fiber precast body.
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| CN1171137A (en) * | 1994-11-16 | 1998-01-21 | B·F·谷德里奇公司 | Pressure gredient CVI/CVD apparatus, process and product |
| FR2924426B1 (en) * | 2007-11-30 | 2011-06-03 | Messier Bugatti | PROCESS FOR MANUFACTURING COMPOSITE MATERIAL PARTS WITH CARBON FIBER REINFORCEMENT |
| CN101478841B (en) * | 2008-12-31 | 2012-05-02 | 西安超码科技有限公司 | Carbon/carbon heating body preparation method for polysilicon hydrogenation furnace |
| CN103342561B (en) * | 2013-06-26 | 2014-11-05 | 中国人民解放军国防科学技术大学 | C/ZrC composite material prepared on basis of vapor infiltration reaction, preparation method thereof and equipment for process |
| CN104451606B (en) * | 2014-12-19 | 2016-10-26 | 中南大学 | A kind of method of carbon/carbon compound material rapid vapor deposition density |
| CN104926345B (en) * | 2015-05-22 | 2017-03-15 | 中国人民解放军国防科学技术大学 | A kind of alumina fibre strengthens carborundum aluminum silicate ceramic and preparation method thereof |
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