CN107578837B - The method of the integrated molding preparation full ceramic coatings fuel pellet of plate - Google Patents
The method of the integrated molding preparation full ceramic coatings fuel pellet of plate Download PDFInfo
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- CN107578837B CN107578837B CN201710958721.7A CN201710958721A CN107578837B CN 107578837 B CN107578837 B CN 107578837B CN 201710958721 A CN201710958721 A CN 201710958721A CN 107578837 B CN107578837 B CN 107578837B
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E30/00—Energy generation of nuclear origin
- Y02E30/30—Nuclear fission reactors
Abstract
The invention discloses the method for the integrated molding preparation full ceramic coatings fuel pellet of plate, to solve the problems, such as in existing FCM preparation of fuel that there are steps many and diverse, is difficult to engineer application, without TRISO distribution of particles is uneven in the ceramic co-fired difficult, preparation process in fuel region and SiC matrix, prepares difficulty etc. without fuel region.The present invention includes: that (1) prepares the compound green tape of SiC/TRISO and single SiC green tape respectively；(2) green compact with superstructure, media layer damage and understructure are made；Wherein, superstructure and understructure are one layer or more of single SiC green tape, the compound green tape of SiC/TRISO that media layer damage is one layer or more；(3) semi-finished product are made after green compact being carried out isostatic cool pressing and dumping processing；(4) finished product is made in semi-finished product after oversintering.The present invention have many advantages, such as simple production process, it is at low cost, with short production cycle, be suitable for industrialized production.
Description
Technical field
The invention belongs to ceramic forming material fields, and in particular to integrated molding prepares the full ceramic coatings cartridge of plate
The method of block.
Background technique
After Fukushima, Japan accident, reactor safety performance becomes the top priority of nuclear power developing.Crash-proof fuel in the world
(ATF) it comes into being.The fuel assembly for nuclear reactor of active service, cladding tubes are the first barriers for stopping fission product, and are split
Unique barrier that object enters circuit is sold of one's property, when involucrum occurs damaged, fission product will enter circuit, lead to reactor circuit
Pollution.And the ceramic fuel of active service such as UO2, that UN, U-Si etc. contain ability to fission product is weak, while corrosion resistants such as UN, U-Si
Corrosion can be poor, and after clad failure, fission product easily enters reactor loop system.
Active service reactor fuel pellet is mostly UO2Ceramics, but there are shortcomings, as thermal conductivity is lower, fracture toughness compared with
Low fission product contains ability difference etc..To solve UO2Ceramic fuel contains the drawback of fission product ability difference, researcher's exploitation
Many novel cladding fuel, such as Metal Substrate dispersion fuel (M3), the micro- cladding fuel (FCM) of full ceramics, spherical coat fuel
Deng.
Wherein, the complete micro- cladding fuel (FCM) of ceramics refers to UO2(UN or other fuel cores) are made into fuel microballoon, it
Afterwards in fuel microsphere surface by layer by layer deposition, interior fine and close pyrolytic carbon layer (IPyC), loose pyrolytic carbon are deposited respectively from inside to outside
Layer (Buffer), fine and close SiC layer and outer fine and close pyrolytic carbon layer (OPyC), obtain cladding multilayer coating structure fuel sphere；It later will combustion
Pellet disperse forms the complete micro- cladding fuel of ceramics in SiC matrix.
FCM fuel has the advantage that 1) there are multilayer coating structure layers for FCM fuel, have the fission product of fuel core
There is very excellent cladding and contain ability, fission product releasing can be effectively prevented.2) due to the thermal conductivity of SiC matrix compared with
Height, the heat that core generates can export quickly, therefore FCM fuel is at runtime, central temperature ratio UO2It is low；3) SiC matrix is resistance to
Corrosive nature is excellent, even if breakage occurs for cladding tubes, coolant enters in fuel rod, will not react, make with SiC matrix
Corrode at pellet.4) FCM fuel matrix fusing point is high, and 2700 DEG C of the decomposition point > of SiC is difficult to occur under LOCA accident
Core meltdown phenomena.5) compared with graphite matrix, it is graphite that air cooled reactor spherical shape, which coats fuel external sheath, due to graphite-structure spy
Sign, micro-molecular gas particles diffusion to lamellar graphite interlayer, therefore the ability of graphite control fission gas release is poor.In addition, by
In FCM there is stronger fission product to contain ability, can effectively improve fuel burn-up, extension is reloaded the time.
However full ceramic coatings preparation of fuel difficulty, SiC ceramic matrix are difficult to sintering densification；Surrounding is without fuel region size
It is difficult to control accurately；In preparation process, especially in isostatic cool pressing or mixing process, coated fuel particles (TRISO particle)
Clad is easy breakage.In order to obtain the FCM fuel pellet of function admirable, researcher attempts kinds of experiments means.As used
Nanometer eutectic infiltration method (NITE) prepares FCM pellet, is prepared using fibrage winding method without fuel region, using the poly- second of dispersing agent
Alkene imines (PEI) dispersed ceramic powder.
Such as: disclosing one kind in the prior art using isopropanol as medium, by TRISO particle and SiC, Al2O3、Y2O3Mixing
Powder is dry-pressing formed, prepares FCM pellet using hot pressed sintering afterwards, and studied pellet heterogeneous microstructure.FCM pellet
Middle TRISO particle agglomeration is obvious, and pellet top is after sintering almost without TRISO particle, and lower part TRISO particle is connected with each other.
A kind of mixed powder of use wet process/hot pressed sintering preparation FCM pellet is for another example also disclosed in the prior art, it finally will be continuous
Fibrage sleeve is bundled in FCM green surface with polyimides film strips, combines machining preparation using hot pressed sintering later
Without fuel region.The FCM pellet density of this method preparation is higher, controllable without fuel region size after processing.But: 1) this substep
Manufacturing method, step are many and diverse, it is difficult to engineering application；2) continuous fiber knitted body is expensive；3) fine during hot pressed sintering
It ties up knitted body and SiC matrix shrinking percentage difference is big, residual stress between the two is big, and there are a large amount of stomatas for transition zone, is being on active service
There is cracking in journey may.
Summary of the invention
It is answered the technical problems to be solved by the present invention are: that there are steps in existing FCM preparation of fuel is many and diverse, is difficult to engineering
With, it is uneven without TRISO distribution of particles in the ceramic co-fired difficult, preparation process in fuel region and SiC matrix, prepared without fuel region it is difficult
Deng problem, and it is an object of the present invention to provide a kind of integrated molding to solve the above problems prepares plate full ceramic coatings fuel pellet
Method.
The present invention is achieved through the following technical solutions:
The method of the integrated molding preparation full ceramic coatings fuel pellet of plate, comprising:
(1) the compound green tape of SiC/TRISO and single SiC green tape are prepared respectively；
(2) green compact with superstructure, media layer damage and understructure are made；Wherein, superstructure and understructure
It is one layer or more of single SiC green tape, the compound green tape of SiC/TRISO that media layer damage is one layer or more；
(3) semi-finished product are made after green compact being carried out isostatic cool pressing and dumping processing；
(4) finished product is made in semi-finished product after oversintering.
Setting through the above way can effectively promote TRISO particle to be evenly distributed in finished product, raw by single SiC
The setting of band can effectively prepare no fuel region, and preparation is simple, and can effectively realize the burning of no fuel region Yu SiC matrix ceramics
Knot.The process step of the invention is relatively easy, is suitable for industrialized production, is convenient for engineer application.Thus, technique solution of the invention
The many drawbacks of the prior art of having determined, such as: NITE technique is difficult without fuel region preparation, multiple moulding process is many and diverse, material by wet type mixing
TRISO particle sedimentation etc..
Further, the compound green tape of the SiC/TRISO the preparation method comprises the following steps:
(11) SiC/TRISO composite mortar and single SiC slurry are prepared respectively；
(12) SiC/TRISO composite mortar and single SiC slurry are poured into the slurry funnel of casting machine, the slurry of casting machine
Funnel is spaced, and slurry funnel two sides are single SiC slurry, and the centre of slurry funnel is SiC/TRISO composite mortar；
(13) curtain coating speed be 20mm/min~40mm/min, drying temperature is 50 DEG C~80 DEG C, edge height is
Tape casting is carried out under conditions of 1.5mm~3mm；
Tape casting process are as follows: when being cast green tape length arrival 80mm~100mm, SiC/TRISO composite pulp will be housed
The funnel part filter of material is put down, and filters out TRISO particle, continues to be cast 10mm~20mm, then will be compound equipped with SiC/TRISO
The funnel part filter of slurry resets；It repeats above-mentioned tape casting process and the compound interval green tape of SiC/TRISO is made；
(14) cut along the green tape middle position without TRISO particle in the compound interval green tape of SiC/TRISO and be made
The compound green tape of SiC/TRISO.
The preparation process of single SiC green tape is identical as the preparation process of the compound green tape of SiC/TRISO in the present invention, thus this
Invention improves casting arrangement, obtains the compound interval green tape of SiC/TRISO and single SiC green tape with spacer structure,
By cutting, laminating, dumping, sintering and subsequent processing obtain high density SiC base FCM fuel pellet, realize FCM fuel
The integrated molding of pellet.Preparation process is simpler, and at low cost, with short production cycle, is suitable for industrialized production.
Further, the SiC/TRISO composite mortar and single SiC slurry the preparation method is as follows:
Firstly, preparing mixed powder after ball milling mixing using raw material；Ball-milling medium is dehydrated alcohol, and mixing ball is
Fine and close SiC ball, ratio of grinding media to material are 4~10:1, incorporation time 8h；
Secondly, by mixed powder and 30wt%~45wt% solvent and 0.5wt%~2wt% dispersant, ball milling
The suspension of stable dispersion is obtained afterwards；
Finally, 4wt%~8wt% bonding agent, 2wt%~6wt% plasticizer and 1wt% are added into the suspension of acquisition
Defoaming agent is uniformly mixed, and de-bubble obtains the slurry of stable dispersion under the vacuum condition of -0.1Pa；
When the slurry of preparation is SiC/TRISO composite mortar, raw material includes SiC staple fiber, SiC particulate, sintering aid
With TRISO particle；Wherein, sintering aid content is 5wt%~10wt%, the volume ratio of SiC staple fiber and SiC particulate is 10~
20:90~80, TRISO granule content are 30vol%~45vol%；
When the slurry of preparation is single SiC slurry, raw material includes SiC staple fiber, SiC particulate and sintering aid；Wherein,
Sintering aid content is 5wt%~10wt%, and the volume ratio of SiC staple fiber and SiC particulate is 10~20:90~80.
FCM fuel pellet thermal shock resistance can be improved by addition SiC staple fiber in the present invention, resists transient condition
Under thermal shock, while adding thermal conductivity and toughness that SiC staple fiber improves FCM fuel pellet, further increase pellet
Pellet burnup is deepened in safety.
Still further, the length < 1mm of the SiC staple fiber, the SiC particulate < 100nm, sintering aid is mole
Than the Al for 3:22O3And Y2O3；
The solvent is the mixed solution of the alcohol that volume ratio is 2:3 and toluene, and the dispersing agent is tetramethyl hydroxide
Ammonium；
The bonding agent is PVB, and the plasticizer is dibutyl phthalate, and the defoaming agent is n-butanol, de-bubble
Time is 10min~40min.
Further, the preparation process of the green compact are as follows:
(21) the compound green tape of the SiC/TRISO met the size requirements and single SiC green tape are cut into；
(22) the compound green tape of SiC/TRISO and single SiC green tape are successively stacked；
(23) green tape stacked is placed in the mold of required size, using one-way shaft pressure, is pressed in 20MPa~40Mpa
Green compact after pressure maintaining 3min~5min is laminated under power.
The pressure of the isostatic cool pressing is 80MPa~150MPa, dwell time 100S.
The process of the dumping processing are as follows:
Firstly, the green compact after static pressure is waited to be placed in Muffle furnace, and it is passed through N2Protection, with 0.3 DEG C/min~0.6 DEG C/min
Heating rate is warming up to 215 DEG C and keeps the temperature 30min；
Secondly, be warming up to 550 DEG C with 0.3 DEG C/min~0.6 DEG C/min heating rate and keep the temperature 1h, it is cold with furnace later
But；
Finally, by green compact after cooling, it is placed in air furnace with 0.3 DEG C/min~0.6 DEG C/min heating rate from room
Temperature is warming up to 300 DEG C and keeps the temperature 30min, and semi-finished product are made in furnace cooling later.
Further, the mode of the sintering is hot pressed sintering, discharge plasma sintering, pressureless sintering or gas pressure sintering.
When the sintering processing is hot pressed sintering, sintering condition are as follows:
Sintering temperature are as follows: 1700 DEG C~1850 DEG C, sintering pressure: 10MPa~30MPa, soaking time are 1~3h, sintering
Atmosphere: N2Or Ar protection, vacuum degree: < 1Pa；
When the sintering processing is discharge plasma sintering, sintering condition are as follows:
Sintering temperature are as follows: 1500 DEG C~1800 DEG C, sintering pressure: 10MPa~20MPa, soaking time are 3min~5min,
Sintering atmosphere: N2Or Ar protection, vacuum degree: < 1Pa；
When the sintering processing is gas pressure sintering, sintering condition are as follows:
Sintering temperature are as follows: 1700 DEG C~1850 DEG C, sintering atmosphere: N2Or Ar, gas pressure: 3MPa~5MPa, when heat preservation
Between be 2~4h；
When the sintering processing is pressureless sintering, sintering condition are as follows:
Sintering temperature are as follows: 1700 DEG C~1850 DEG C, sintering atmosphere: N2Or Ar protection, soaking time are 2h~4h, vacuum
Degree: < 1Pa.
After being combined by above-mentioned technique, it can effectively make FCM fuel pellet thermal conductivity height, the good toughness of preparation, have simultaneously
There is excellent aqueous corrosion performance resistant to high temperatures, it is strong to fission product containing ability, it can achieve deeper burnup, when effectively extension is reloaded
Between.
Further, surface polishing treatment is carried out using emery grinding wheel after sintering, until finished product is made without obvious scratch.
Compared with prior art, the present invention having the following advantages and benefits:
1, the present invention realizes the integrated molding of FCM fuel pellet, and simple production process, at low cost, with short production cycle,
Suitable for industrialized production；
2, FCM fuel pellet thermal shock resistance can be improved in the present invention, resists the thermal shock under transient condition, thermal conductivity
And toughness, the safety of pellet is further increased, pellet burnup is deepened；
3, FCM fuel pellet thermal conductivity height prepared by the present invention, good toughness, while there is excellent aqueous corrosion resistant to high temperatures
Can, it is strong to fission product containing ability, it can achieve deeper burnup, effectively extend and reload the time.
Detailed description of the invention
Attached drawing described herein is used to provide to further understand the embodiment of the present invention, constitutes one of the application
Point, do not constitute the restriction to the embodiment of the present invention.In the accompanying drawings:
Fig. 1 is the microstructure morphology having in the compound green tape of SiC/TRISO at TRISO particle in the present invention.
Fig. 2 is the microstructure morphology at the interface in TRISO particle and SiC particulate area in the present invention.
Fig. 3 is the microstructure morphology of single SiC green tape in the present invention.
Fig. 4 is the fracture apperance figure of FCM fuel pellet in the present invention.
Label and corresponding parts title in attached drawing:
1-TRISO particle；The granulomere 2-SiC.
Specific embodiment
To make the objectives, technical solutions, and advantages of the present invention clearer, below with reference to embodiment, the present invention is made
Further to be described in detail, exemplary embodiment of the invention and its explanation for explaining only the invention, are not intended as to this
The restriction of invention.
Embodiment 1
The method of the integrated molding preparation full ceramic coatings fuel pellet of plate, comprising:
(1) the compound green tape of SiC/TRISO and single SiC green tape are prepared respectively；
Specific preparation method is: by the SiC staple fiber of length < 1mm, the SiC particulate of partial size < 100nm, sintering aid and
TRISO particle ball milling mixing；Wherein, sintering aid content is 6wt%, and SiC staple fiber accounts for SiC particulate 10vol%, TRISO
Grain content is 40vol%, the Al that sintering aid is 3:2 by molar ratio2O3And Y2O3.Ball-milling medium is dehydrated alcohol, and mixing ball is
Fine and close SiC ball, ratio of grinding media to material 10:1, incorporation time 8h, 60 DEG C of dryings obtain mixed powder later.The mixed powder that will be obtained
It is mixed with 35wt% solvent and 1% tetramethylammonium hydroxide, ball milling 8h obtains the suspension of stable dispersion；Wherein solvent is alcohol
The mixing liquid constituted with toluene, the volume ratio of alcohol and toluene is 2:3 in mixing liquid.It is added 6wt%'s into suspension
PVB, 3wt% dibutyl phthalate and 1wt% n-butanol mix 2h, the de-bubble 30min under the vacuum condition of -0.1Pa,
Obtain the SiC/TRISO composite mortar of stable dispersion.Single SiC slurry is consistent with the preparation method of SiC/TRISO composite mortar,
Institute does not have TRISO particle the difference lies in that in single SiC slurry, other proportions and technological parameter are multiple with SiC/TRISO
It is identical to close slurry.
The SiC/TRISO composite mortar of acquisition and single SiC slurry are poured into the slurry funnel of casting machine, are cast
Molding.It is integrally formed to realize without fuel region, during tape casting, the slurry funnel of casting machine need to be separated, two sides are
Single SiC slurry, centre are SiC/TRISO composite mortar, and two sides and intermediate width ratio are according to actual components size adjustable.Curtain coating
Speed is 20mm/min, and drying temperature is 50 DEG C, and edge height 2mm is adjustable.When tape casting green tape length reaches 80mm, it will fill
There is the funnel part filter of SiC/TRISO composite mortar to put down, filter out TRISO particle, continues to be cast 10mm, by funnel part
Filter resets, and repeats to be cast forming process；SiC/TRISO compound is obtained after slurry after drying is removed from casting machine
Every green tape, then the centre along the interval green tape of no TRISO particle is cut off, and green tape width is 60mm, and it is compound to obtain SiC/TRISO
Green tape.
It is poured into the slurry funnel of casting machine using single SiC slurry, carries out tape casting；Casting conditions and SiC/
The casting conditions of the compound green tape of TRISO are identical, and the green tape that tape casting is prepared is cut into identical as the compound green tape of SiC/TRISO
Size, it is single SiC green tape that green tape is obtained after the cutting.
(2) green compact are prepared；
Specific preparation method is: the compound green tape of 10 layers of SiC/TRISO with a thickness of 1.5mm is stacked together, top and bottom
It is each to place 2 layers with a thickness of the single SiC green tape of 1.5mm, as no fuel region.
The green tape placed is laminated: using one-way shaft pressure, green tape being placed in stainless steel mould, is pressurizeed.Pressure
Green compact are obtained after laminating for 20MPa, dwell time 3min.
(3) semi-finished product are made after green compact being carried out isostatic cool pressing and dumping processing；
The detailed process of isostatic cool pressing is: green compact are carried out isostatic cool pressing, pressure 100MPa, dwell time 100S.
Raw embryo after isostatic cool pressing carries out dumping processing, to prevent TRISO particle from cracking the burn off of C, using twice-debinding process
Technique.Specific steps: the green compact after equal static pressure are placed in Muffle furnace, and are passed through N2Protection, with the heating rate of 0.3 DEG C/min
It is warming up to 215 DEG C and keeps the temperature 30min.550 DEG C are warming up to the heating rate of 0.3 DEG C/min and keep the temperature 1h, furnace cooling later.
By green compact after cooling, it is placed in air furnace and handled except C.With the heating rate of 0.3 DEG C/min from room temperature to 300 DEG C
And 30min is kept the temperature, and furnace cooling later, the semi-finished product after obtaining dumping.
(4) finished product is made in semi-finished product after oversintering；
The present embodiment is hot pressed sintering preparation FCM fuel pellet, and specific preparation method is: the FCM green compact after dumping are set
In graphite jig, and carry out hot pressed sintering.Graphite jig size matches with FCM green compact size.Hot pressed sintering temperature are as follows:
1850 DEG C, sintering pressure: 20MPa, soaking time 2h, sintering atmosphere: N2Protection, vacuum degree: < 1Pa.Process flow are as follows: with
10 DEG C/min is warming up to 1000 DEG C, keeps the temperature 1h；10 DEG C/min is warming up to 1850 DEG C, keeps the temperature 2h；15 DEG C/min is cooled to 1000 DEG C,
It cools to room temperature with the furnace later, obtains FCM fuel pellet.
Sintered FCM fuel pellet carries out dimensional measurement, is machined to standard size with grinding machine, grinder wheel uses Buddha's warrior attendant
Sand grinding wheel.Surface polishing treatment is carried out later, is successively carried out using 400,800,1000,1500 and 2000 mesh diamond dust waterproof abrasive papers
Polishing, until surface is without obvious scratch.
Embodiment 2
The present embodiment the difference from embodiment 1 is that, the technological parameter of each step is different in the present embodiment, and specific setting is such as
Under:
(1) the compound green tape of SiC/TRISO and single SiC green tape are prepared respectively；
Specific preparation method is: by the SiC staple fiber of length < 1mm, the SiC particulate of partial size < 100nm, sintering aid and
TRISO particle ball milling mixing；Wherein, sintering aid content is 10wt%, and SiC staple fiber accounts for SiC particulate 15vol%, TRISO
Grain content is 35vol%, the Al that sintering aid is 3:2 by molar ratio2O3And Y2O3.Ball-milling medium is dehydrated alcohol, and mixing ball is
Fine and close SiC ball, ratio of grinding media to material 10:1, incorporation time 8h, 60 DEG C of dryings obtain mixed powder later.The mixed powder that will be obtained
It is mixed with 35wt% solvent and 1% tetramethylammonium hydroxide, ball milling 8h obtains the suspension of stable dispersion；Wherein solvent is alcohol
The mixing liquid constituted with toluene, the volume ratio of alcohol and toluene is 2:3 in mixing liquid.It is added 5wt%'s into suspension
PVB, 4wt% dibutyl phthalate and 1wt% n-butanol mix 2h, the de-bubble 20min under the vacuum condition of -0.1Pa,
Obtain the SiC/TRISO composite mortar of stable dispersion.Single SiC slurry is consistent with the preparation method of SiC/TRISO composite mortar,
Institute does not have TRISO particle the difference lies in that in single SiC slurry, other proportions and technological parameter are multiple with SiC/TRISO
It is identical to close slurry.
The SiC/TRISO composite mortar of acquisition and single SiC slurry are poured into the slurry funnel of casting machine, are cast
Molding.It is integrally formed to realize without fuel region, during tape casting, the slurry funnel of casting machine need to be separated, two sides are
Single SiC slurry, centre are SiC/TRISO composite mortar, and two sides and intermediate width ratio are according to actual components size adjustable.Curtain coating
Speed is 30mm/min, and drying temperature is 60 DEG C, edge height 3mm.When tape casting green tape length reaches 100mm, it will be equipped with
The funnel part filter of SiC/TRISO composite mortar is put down, and filters out TRISO particle, continues to be cast 15mm, by funnel part mistake
Filter resets, and repeats to be cast forming process；The compound interval SiC/TRISO is obtained after slurry after drying is removed from casting machine
Green tape, then the centre along the interval green tape of no TRISO particle is cut off, and green tape width is 50mm, obtains the compound life of SiC/TRISO
Band.
It is poured into the slurry funnel of casting machine using single SiC slurry, carries out tape casting；Casting conditions and SiC/
The casting conditions of the compound green tape of TRISO are identical, and the green tape that tape casting is prepared is cut into identical as the compound green tape of SiC/TRISO
Size, it is single SiC green tape that green tape is obtained after the cutting.
(2) green compact are prepared；
Specific preparation method is: the compound green tape of 15 layers of SiC/TRISO with a thickness of 3mm being stacked together, top and bottom are each
3 layers are placed with a thickness of the single SiC green tape of 2mm, as no fuel region.
The green tape placed is laminated: using one-way shaft pressure, green tape being placed in stainless steel mould, is pressurizeed.Pressure
Green compact are obtained after laminating for 30MPa, dwell time 4min.
(3) semi-finished product are made after green compact being carried out isostatic cool pressing and dumping processing；
The detailed process of isostatic cool pressing is: green compact are carried out isostatic cool pressing, pressure 120MPa, dwell time 100S.
Raw embryo after isostatic cool pressing carries out dumping processing, to prevent TRISO particle from cracking the burn off of C, using twice-debinding process
Technique.Specific steps: the green compact after equal static pressure are placed in Muffle furnace, and are passed through N2Protection, with the heating rate of 0.4 DEG C/min
It is warming up to 215 DEG C and keeps the temperature 30min.550 DEG C are warming up to the heating rate of 0.4 DEG C/min and keep the temperature 1h, furnace cooling later.
By green compact after cooling, it is placed in air furnace and handled except C.With the heating rate of 0.4 DEG C/min from room temperature to 300 DEG C
And 30min is kept the temperature, and furnace cooling later, the semi-finished product after obtaining dumping.
(4) finished product is made in semi-finished product after oversintering；
The present embodiment is hot pressed sintering preparation FCM fuel pellet, and specific preparation method is: the FCM green compact after dumping are set
In graphite jig, and carry out hot pressed sintering.Graphite jig size matches with FCM green compact size.Hot pressed sintering temperature are as follows:
1750 DEG C, sintering pressure: 25MPa, soaking time 4h, sintering atmosphere: N2Protection, vacuum degree: < 1Pa.Process flow are as follows: with
15 DEG C/min is warming up to 1000 DEG C, keeps the temperature 1h；15 DEG C/min is warming up to 1850 DEG C, keeps the temperature 2h；15 DEG C/min is cooled to 1000 DEG C,
It cools to room temperature with the furnace later, obtains FCM fuel pellet.
Sintered FCM fuel pellet carries out dimensional measurement, is machined to standard size with grinding machine, grinder wheel uses Buddha's warrior attendant
Sand grinding wheel.Surface polishing treatment is carried out later, is successively carried out using 400,800,1000,1500 and 2000 mesh diamond dust waterproof abrasive papers
Polishing, until surface is without obvious scratch.
Embodiment 3
The present embodiment the difference from embodiment 1 is that, the mode that is sintered in the present embodiment is different, is specifically provided that
(a) when sintering processing is discharge plasma sintering, sintering process are as follows:
FCM green compact after dumping are placed in graphite jig, and carry out discharge plasma sintering.Graphite jig size with
FCM green compact size matches.Sintering temperature are as follows: 1700 DEG C, sintering pressure: 20MPa, soaking time: 5min, sintering atmosphere: N2；
Vacuum degree: < 1Pa.Process flow are as follows: be warming up to 1000 DEG C with 50 DEG C/min, keep the temperature 1min；100 DEG C/min is warming up to 1700
DEG C, keep the temperature 5min；100 DEG C/min is cooled to 1000 DEG C, keeps the temperature 2min, cools to room temperature with the furnace later, obtains FCM cartridge
Block.
(b) when sintering processing is gas pressure sintering, sintering process are as follows:
FCM green compact after dumping are placed in graphite jig, and carry out gas pressure sintering.Graphite jig inner cavity is raw greater than FCM
Base.Sintering temperature are as follows: 1800 DEG C, atmospheric pressure: 5MPa, soaking time: 4h, sintering atmosphere: N2.Process flow are as follows: first will
Furnace chamber vacuumize process, vacuum degree < 1Pa, is filled with N later2, air pressure 5MPa opens breather valve, and it is subsequent to heat up, specifically:
1000 DEG C are warming up to 10 DEG C/min, keeps the temperature 1h；10 DEG C/min is warming up to 1800 DEG C, keeps the temperature 4h；15 DEG C/min is cooled to 1000
DEG C, 0.5h is kept the temperature, cools to room temperature with the furnace later, obtains FCM fuel pellet.
(c) when formula is pressureless sintering, sintering process are as follows:
FCM green compact after dumping are placed in graphite jig, and carry out pressureless sintering.Graphite jig inner cavity is raw greater than FCM
Base.Sintering temperature is 1850 DEG C, sintering atmosphere: Ar protection, soaking time 4h, vacuum degree: < 1Pa.Process flow are as follows: with 15
DEG C/min is warming up to 1000 DEG C, keep the temperature 1h；15 DEG C/min is warming up to 1850 DEG C, keeps the temperature 4h；15 DEG C/min is cooled to 1000 DEG C, it
After cool to room temperature with the furnace, obtain FCM fuel pellet.
End properties in above-described embodiment is detected, testing result is as shown in table 1.
Table 1
By table 1 it is found that mode of the invention is not only only capable of effectively overcoming step in existing FCM preparation of fuel many and diverse, difficult
With engineer application, it is uneven without TRISO distribution of particles in the ceramic co-fired difficult, preparation process in fuel region and SiC matrix, without fuel region
The problems such as preparation is difficult has the advantages that simple production process, at low cost, with short production cycle, suitable for industrialized production；And
The finished product prepared also is set to have thermal conductivity high, good toughness, thermal shock resistance is high, and aqueous corrosion performance resistant to high temperatures is strong, to fission
Product contains the advantages that ability is strong, can effectively reach deeper burnup, and extension is reloaded the time.
Above-described specific embodiment has carried out further the purpose of the present invention, technical scheme and beneficial effects
It is described in detail, it should be understood that being not intended to limit the present invention the foregoing is merely a specific embodiment of the invention
Protection scope, all within the spirits and principles of the present invention, any modification, equivalent substitution, improvement and etc. done should all include
Within protection scope of the present invention.
Claims (8)
1. the method for the integrated molding preparation full ceramic coatings fuel pellet of plate characterized by comprising
(1) the compound green tape of SiC/TRISO and single SiC green tape are prepared respectively；
(2) green compact with superstructure, media layer damage and understructure are made；Wherein, superstructure and understructure are
One layer or more of single SiC green tape, the compound green tape of SiC/TRISO that media layer damage is one layer or more；
(3) semi-finished product are made after green compact being carried out isostatic cool pressing and dumping processing；
(4) finished product is made in semi-finished product after oversintering；
The compound green tape of SiC/TRISO the preparation method comprises the following steps:
(11) SiC/TRISO composite mortar and single SiC slurry are prepared respectively；
(12) SiC/TRISO composite mortar and single SiC slurry are poured into the slurry funnel of casting machine, the slurry leakage of casting machine
Bucket is spaced, and slurry funnel two sides are single SiC slurry, and the centre of slurry funnel is SiC/TRISO composite mortar；
(13) curtain coating speed be 20mm/min~40mm/min, drying temperature is 50 DEG C~80 DEG C, edge height be 1.5mm~
Tape casting is carried out under conditions of 3mm；
Tape casting process are as follows:, will be equipped with SiC/TRISO composite mortar when being cast green tape length arrival 80mm~100mm
Funnel part filter is put down, and filters out TRISO particle, continues to be cast 10mm~20mm, then SiC/TRISO composite mortar will be housed
Funnel part filter reset；It repeats above-mentioned tape casting process and the compound interval green tape of SiC/TRISO is made；
(14) cut along the green tape middle position without TRISO particle in the compound interval green tape of SiC/TRISO and SiC/ is made
The compound green tape of TRISO；
The preparation process of the green compact are as follows:
(21) the compound green tape of the SiC/TRISO met the size requirements and single SiC green tape are cut into；
(22) the compound green tape of SiC/TRISO and single SiC green tape are successively stacked；
(23) green tape stacked is placed in the mold of required size, using one-way shaft pressure, under 20MPa~40Mpa pressure
Pressure maintaining 3min~5min laminated after green compact.
2. the method for the integrated molding preparation full ceramic coatings fuel pellet of plate according to claim 1, feature exist
In, the SiC/TRISO composite mortar and single SiC slurry the preparation method is as follows:
Firstly, preparing mixed powder after ball milling mixing using raw material；Ball-milling medium is dehydrated alcohol, and mixing ball is densification
SiC ball, ratio of grinding media to material are 4~10:1, incorporation time 8h；
Secondly, mixed powder and 30wt%~45wt% solvent and 0.5wt%~2wt% dispersant are obtained after ball milling
Obtain the suspension of stable dispersion；
Finally, 4wt%~8wt% bonding agent, 2wt%~6wt% plasticizer and 1wt% defoaming are added into the suspension of acquisition
Agent is uniformly mixed, and de-bubble obtains the slurry of stable dispersion under the vacuum condition of -0.1Pa；
When the slurry of preparation be SiC/TRISO composite mortar when, raw material include SiC staple fiber, SiC particulate, sintering aid and
TRISO particle；Wherein, sintering aid content is 5wt%~10wt%, the volume ratio of SiC staple fiber and SiC particulate is 10~
20:90~80, TRISO granule content are 30vol%~45vol%；
When the slurry of preparation is single SiC slurry, raw material includes SiC staple fiber, SiC particulate and sintering aid；Wherein, it is sintered
Auxiliary agent content is 5wt%~10wt%, and the volume ratio of SiC staple fiber and SiC particulate is 10~20:90~80.
3. the method for the integrated molding preparation full ceramic coatings fuel pellet of plate according to claim 2, feature exist
In the length < 1mm of the SiC staple fiber, the SiC particulate < 100nm, sintering aid is the Al that molar ratio is 3:22O3With
Y2O3；
The solvent is the mixed solution of the alcohol that volume ratio is 2:3 and toluene, and the dispersing agent is tetramethylammonium hydroxide；
The bonding agent is PVB, and the plasticizer is dibutyl phthalate, and the defoaming agent is n-butanol, de-bubble time
For 10min~40min.
4. the method for the integrated molding preparation full ceramic coatings fuel pellet of plate according to claim 1, feature exist
In the pressure of the isostatic cool pressing is 80MPa~150MPa, dwell time 100S.
5. the method for the integrated molding preparation full ceramic coatings fuel pellet of plate according to claim 1, feature exist
In the process of the dumping processing are as follows:
Firstly, the green compact after static pressure is waited to be placed in Muffle furnace, and it is passed through N2Protection, with 0.3 DEG C/min~0.6 DEG C/min heating
Speed is warming up to 215 DEG C and keeps the temperature 30min；
Secondly, be warming up to 550 DEG C with 0.3 DEG C/min~0.6 DEG C/min heating rate and keep the temperature 1h, furnace cooling later；
Finally, by green compact after cooling, it is placed in air furnace with 0.3 DEG C/min~0.6 DEG C/min heating rate from room temperature liter
Temperature is to 300 DEG C and keeps the temperature 30min, and semi-finished product are made in furnace cooling later.
6. the method for the integrated molding preparation full ceramic coatings fuel pellet of plate according to claim 1, feature exist
In the mode of the sintering is hot pressed sintering, discharge plasma sintering, pressureless sintering or gas pressure sintering.
7. the method for the integrated molding preparation full ceramic coatings fuel pellet of plate according to claim 1, feature exist
In, when the sintering processing is hot pressed sintering, sintering condition are as follows:
Sintering temperature are as follows: 1700 DEG C~1850 DEG C, sintering pressure: 10MPa~30MPa, soaking time be 1~3h, sintering atmosphere:
N2Or Ar protection, vacuum degree: < 1Pa；
When the sintering processing is discharge plasma sintering, sintering condition are as follows:
Sintering temperature are as follows: 1500 DEG C~1800 DEG C, sintering pressure: 10MPa~20MPa, soaking time are 3min~5min, sintering
Atmosphere: N2Or Ar protection, vacuum degree: < 1Pa；
When the sintering processing is gas pressure sintering, sintering condition are as follows:
Sintering temperature are as follows: 1700 DEG C~1850 DEG C, sintering atmosphere: N2Or Ar, gas pressure: 3MPa~5MPa, soaking time 2
~4h；
When the sintering processing is pressureless sintering, sintering condition are as follows:
Sintering temperature are as follows: 1700 DEG C~1850 DEG C, sintering atmosphere: N2Or Ar protection, soaking time are 2h~4h, vacuum degree: <
1Pa。
8. the method for the integrated molding preparation full ceramic coatings fuel pellet of plate according to claim 1, feature exist
In using emery grinding wheel progress surface polishing treatment after sintering, until finished product is made without obvious scratch.
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| CN108806804B (en) * | 2018-05-28 | 2020-07-28 | 广东核电合营有限公司 | SiC fiber reinforced fuel pellet and preparation method thereof |
| CN109979610B (en) * | 2019-02-28 | 2020-11-24 | 中国工程物理研究院材料研究所 | Double-component co-doped thermodynamic enhancement type uranium dioxide fuel pellet and preparation method thereof |
| CN113643829B (en) * | 2021-07-29 | 2022-12-20 | 清华大学 | Preparation method of FCM fuel pellet based on tape casting |
| CN113651635B (en) * | 2021-08-17 | 2022-06-21 | 西北工业大学 | Novel porous ceramic composite fuel pellet and preparation method thereof |
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