Highly thermally conductive and highly dense SiC f SiC nuclear fuel cladding tube and method of making

Abstract

This invention provides a SiC f The invention relates to a SiC nuclear fuel cladding tube and its preparation method, comprising: Step 1, SiC fiber preform preparation: wrapping a layer of SiC short fiber mesh around the surface of a SiC fiber braid, and introducing SiC short fibers into the SiC fiber braid using needle punching technology, so that the SiC short fibers are uniformly distributed radially to obtain a SiC fiber preform; Step 2, interface layer preparation; Step 3, first-stage SiC matrix deposition; Step 4, ceramic slurry preparation and impregnation; Step 5, second-stage SiC matrix deposition; and Step 6, MAX phase modified SiC coating preparation. The preparation method of this invention, based on a two-dimensional braided SiC fiber preform, introduces SiC needle-punched fibers radially using needle punching technology, increasing the SiC content. f The SiC core-clad radial heat conduction channel greatly improves the radial heat conduction performance of the clad tube.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of nuclear power generation, and relates to a nuclear fuel cladding, in particular to a high-thermal-conductivity and high-density SiC f / SiC nuclear fuel cladding tube and a preparation method thereof. BACKGROUND

[0002] The pressurized water reactor is the most main grid-connected power generation reactor type at present, and the fuel cladding thereof is the first barrier for preventing nuclear fuel and radioactive products from leaking. Developing a new generation of pressurized water reactor nuclear fuel cladding material which has radiation resistance, high temperature resistance, good chemical stability, good environmental performance (does not react violently with water and has a small amount of hydrogen production), can maintain the integrity of the reactor core in a nuclear accident, and ensures that nuclear fuel, fission products and radioactive gases do not leak, has become an urgent key problem to be solved in the international safe development of nuclear power. SUMMARY

[0003] In view of the deficiencies in the prior art, the purpose of the application is to provide a high-thermal-conductivity and high-density SiC f / SiC nuclear fuel cladding tube, which solves the technical problem that the thermal conductivity, especially the radial thermal conductivity, of the nuclear fuel cladding tube in the prior art needs to be further improved.

[0004] The purpose of the application is to provide a preparation method of a high-thermal-conductivity and high-density SiC f / SiC nuclear fuel cladding tube, which solves the technical problem that the CVI process in the prior art is difficult to obtain high-density SiC f / SiC composite material.

[0005] In order to solve the above technical problems, the application adopts the following technical solutions:

[0006] A preparation method of a SiC f / SiC nuclear fuel cladding tube, which comprises the following steps:

[0007] Step one, SiC fiber preform preparation:

[0008] A layer of SiC short fiber web is wrapped on the surface of the SiC fiber woven body, the SiC short fibers are introduced into the SiC fiber woven body by using the needle punching technology, the SiC short fibers are uniformly distributed in the radial direction, and the SiC fiber preform is obtained.

[0009] Step two, interface layer preparation:

[0010] A layer of pyrolytic carbon interface layer is deposited on the SiC fiber preform obtained in step one by using the chemical vapor infiltration method, and the SiC fiber preform with the interface layer is obtained.

[0011] Step three, first-stage SiC matrix deposition:

[0012] SiC / SiC cladding tube first stage process piece is obtained by depositing SiC matrix on the SiC fiber preform with interface layer prepared in step two by chemical vapor infiltration method to the density of 1.7-1.9 g / cm 3 . f .

[0013] Step four, ceramic slurry preparation and impregnation:

[0014] The ceramic powder and sodium carboxymethyl cellulose (i.e. CMC) aqueous solution are uniformly mixed and ball milled to obtain a ceramic slurry, and the SiC f / SiC cladding tube first stage process piece obtained in step three is immersed in the ceramic slurry in an impregnation tank, the impregnation tank is first vacuumed to 10-20 kPa and then pressure is maintained, then the SiC f / SiC cladding tube first stage process piece and the ceramic slurry are put into a sealed container, inert gas is filled to pressurize to 0.8-3.0 MPa and pressure is maintained, the preform is taken out and dried to obtain the slurry-impregnated cladding tube.

[0015] Step five, second stage SiC matrix deposition:

[0016] The SiC matrix is deposited on the slurry-impregnated cladding tube obtained in step four by chemical vapor infiltration method to the density of 2.6-2.8 g / cm 3 , to obtain a SiC f / SiC cladding tube second stage process piece.

[0017] Step six, MAX phase modified SiC coating preparation:

[0018] A layer of uniformly distributed ceramic slurry is prepared on the surface of the SiC f / SiC cladding tube second stage process piece prepared in step five, and after drying, chemical vapor deposition method is adopted to deposit SiC to realize MAX phase modified SiC coating preparation, to obtain a SiC f / SiC nuclear fuel cladding tube.

[0019] The present application also has the following technical features:

[0020] In step one, the needle density of the needle punching technology is 5-13 needles / cm 2 .

[0021] In step one, the SiC fiber braid is braided by third generation SiC fibers, the fiber linear density is 0.5 k, the fiber braiding angle is 45°, the braiding thickness is 0.5-1.2 mm, and the fiber volume fraction is 30-40%.

[0022] In step one, the SiC short fiber web has single fiber in the form of fiber length of 60-80mm, and volume fraction of 10%-15%.

[0023] In step two, the thickness of the pyrolytic carbon interface layer is 150-350nm.

[0024] In step two, the reaction gas of the chemical vapor infiltration method is a mixed gas of natural gas and propane, and the molar ratio of the two is (3-4):1.

[0025] In step two, the deposition temperature of the chemical vapor infiltration method is 1010±50℃, the furnace gas pressure is 2000-4000Pa, and the deposition time is 40-80h.

[0026] In step three and step five, the reaction gas of the chemical vapor infiltration method is a mixed gas of trichloromethylsilane, hydrogen and argon, and the molar ratio of hydrogen to trichloromethylsilane is 7-10, and the flow ratio of carrier gas hydrogen, dilution hydrogen and protective gas argon is 3:1:3 (volume ratio).

[0027] In step three and step five, the deposition temperature of the chemical vapor infiltration method is 1050±50℃, and the furnace gas pressure is 2500-4500Pa.

[0028] In step four, the ceramic powder is Ti3SiC2, Ti3AlC2 or SiC. The particle size of the ceramic powder is less than 1um.

[0029] In step four, the mass fraction of the sodium carboxymethyl cellulose aqueous solution is 0.5%-1.5%, and the mass ratio of the ceramic powder to the sodium carboxymethyl cellulose aqueous solution is (1-2):10.

[0030] In step four, the ball milling process lasts for no less than 24h, and the rotation speed of the ball mill is 200-450r / min.

[0031] In step four, the holding time of the vacuum impregnation and the pressure impregnation is 30-60min.

[0032] In step six, the preparation method of the ceramic slurry includes brushing method, spraying method or pulling and dipping method, and the pulling and dipping method is prepared at a pulling speed of 2-5mm / min, and the pulling frequency is not less than 2 times.

[0033] In step six, the deposition time of the chemical vapor deposition method is 100-150h.

[0034] The application also protects a SiC f / SiC nuclear fuel cladding tube, the SiC fThe SiC / SiC nuclear fuel cladding tube adopts the SiC f The preparation method of the SiC / SiC nuclear fuel cladding tube is prepared.

[0035] Compared with the prior art, the present application has the following technical effects:

[0036] (I) The preparation method of the present application introduces SiC needle fibers in the radial direction on the basis of the two-dimensional woven SiC fiber preform through the needle punching technology, increases the SiC f The SiC / SiC nuclear cladding radial heat conduction channel greatly improves the radial heat conduction performance of the cladding tube.

[0037] (II) After the matrix densification in the fiber bundle of the preform, the present application timely introduces ceramic particles between the fiber bundles through ceramic slurry impregnation, disperses the large pores between the fiber bundles into small pores, and is beneficial to the SiC f The SiC / SiC nuclear cladding is further densified, and the SiC deposition efficiency is improved.

[0038] (III) The preparation method of the present application introduces high-thermal-conductivity MAX phase (Ti3SiC2 or Ti3AlC2) to improve the thermal conductivity of the material. The MAX phase modified SiC coating is prepared by slurry dipping combined with chemical vapor deposition method, which improves the toughness of the coating and improves the thermal conductivity of the coating.

[0039] (IV) The cladding tube of the present application improves the densification and thermal conductivity of the cladding tube, which is beneficial to promote the application of SiC f / SiC in nuclear reactors. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 is a flowchart of the preparation method of the present application.

[0041] Figure 2 is a scanning electron microscope photo of the Ti3SiC2 MAX phase modified and unmodified SiC / SiC composite material in embodiment 1 of the present application.

[0042] Figure 3 is a scanning electron microscope photo of the Ti3SiC2 MAX phase modified and unmodified SiC / SiC nuclear cladding in embodiment 2 of the present application.

[0043] Figure 4 is the thermal conductivity of the Ti3AlC2 MAX phase modified and unmodified SiC / SiC nuclear cladding in embodiment 3 of the present application.

[0044] The specific content of the present application is further explained and described in detail in combination with the embodiments. DETAILED DESCRIPTION

[0045] It should be noted that all the materials and equipment in the present application, in the absence of special explanation, adopt the materials and equipment known in the art.

[0046] SiC f / SiC composite material has good anti-radiation damage, excellent high-temperature chemical inertness and low activity, excellent high-temperature strength (high-temperature resistance) and structural stability.

[0047] SiC f / SiC nuclear fuel cladding tube usually adopts two-dimensional woven SiC fiber preform, and densification is realized by chemical vapor infiltration process (CVI) to deposit SiC matrix, but the CVI process will inevitably produce 10% porosity, which leads to that the gas tightness of the cladding tube cannot meet the service needs, the material is not dense, which makes the thermal conductivity poor, especially the two-dimensional woven structure lacks radial heat conduction channels, the cladding tube has poor radial heat conduction, which affects the application of SiC f / SiC in nuclear fuel cladding tube.

[0048] The present application provides a kind of high thermal conductivity high density SiC f / SiC nuclear fuel cladding tube and its preparation method. Based on two-dimensional woven SiC fiber preform, SiC fibers are introduced in the radial direction of the cladding tube by needle punching technology, which increases the radial heat conduction channels of SiC f / SiC nuclear cladding, greatly improves the radial heat conduction performance of the cladding tube; during the densification process of chemical vapor deposition of SiC matrix, ceramic particles are introduced by impregnating ceramic slurry between the fiber bundles in time, which disperses the large pores between the fiber bundles into small pores, which is beneficial to the further densification of SiC f / SiC nuclear cladding, improves the deposition efficiency of SiC; at the same time, by introducing high thermal conductivity MAX phase (Ti3SiC2 or Ti3AlC2), the thermal conductivity of the cladding tube is improved; finally, by slurry dipping combined with chemical vapor deposition method, MAX (i.e. ternary layered structure ceramic material) phase modified SiC coating is prepared on the surface of the cladding tube, which not only improves the toughness of the coating, but also improves the thermal conductivity of the coating. The present application improves the densification and thermal conductivity of the cladding tube, which is beneficial to the application of SiC f / SiC in nuclear reactor.

[0049] According to the above technical solution, the specific embodiments of the present application are given below. It should be noted that the present application is not limited to the following specific embodiments, and any equivalent transformation based on the technical solution of the present application falls within the scope of protection of the present application.

[0050] Example 1:

[0051] This embodiment gives a kind of high thermal conductivity high density SiC f / SiC nuclear fuel cladding tube and its preparation method, such as Figure 1As shown, the method is carried out according to the following steps:

[0052] Step one, SiC fiber preform preparation:

[0053] A SiC fiber preform is prepared on the graphite core using the third-generation SiC fiber woven sheath pipe, with a fiber line density of 0.5k, a weaving angle of 45°, a weaving thickness of 0.8mm, and a fiber volume fraction of 30%; then a layer of short SiC fiber mesh tire is wrapped on the surface of the woven body, the fibers in the mesh tire exist in the form of single fiber, the fiber length is about 60mm, and the volume fraction is 15%; SiC short fibers are introduced into the SiC fiber preform radially uniformly by needle punching technology, with a needle punching density of 5 needles / cm 2 .

[0054] Step two, interface layer preparation:

[0055] Pyrolytic carbon interface is deposited by chemical vapor infiltration method, under the condition of 1000℃, 2000Pa, for about 80h, the reaction gas is a mixture of natural gas and propane with a mole ratio of 3, and the thickness of the prepared pyrolytic carbon interface is about 200nm.

[0056] Step three, first stage SiC matrix deposition:

[0057] SiC matrix is deposited by chemical vapor infiltration method, the reaction gas trichloromethylsilane is introduced into the reaction chamber with hydrogen as carrier gas, the mole ratio of hydrogen to trichloromethylsilane is 8, the flow rate of carrier gas hydrogen:dilution hydrogen:protective gas argon=3:1:3, under the condition of 1050℃, 3500Pa, depositing for about 280h to the sheath density of ~1.78g / cm 3 .

[0058] Step four, ceramic slurry preparation and impregnation:

[0059] Ti3SiC2 ceramic powder with a particle size of ~0.8µm is added to a 0.8% mass fraction carboxymethyl cellulose sodium CMC aqueous solution, the mass ratio of Ti3SiC2 ceramic powder to CMC aqueous solution is 1:10, ball milling for 36h to prepare the ceramic slurry; the sheath pipe with a density of about 1.78g / cm 3 prepared in step three is immersed in the ceramic slurry, vacuumized to an air pressure in the impregnation tank below 20kPa, kept for 30min, then the sheath pipe and the slurry are put into a sealed container and inert gas is introduced to pressurize to 0.8MPa, kept for 60min, then taken out and dried.

[0060] Step five, second stage SiC matrix deposition:

[0061] The deposition method is basically the same as that in step three, until the SiC fThe density of the SiC cladding tube is ~2.80g / cm 3 .

[0062] Step six, MAX phase modified SiC coating preparation:

[0063] The SiC f The SiC f / SiC nuclear fuel cladding tube.

[0064] Example 2:

[0065] This example gives a high-thermal-conductivity high-density SiC f / SiC nuclear fuel cladding tube. Figure 1 As shown in the figure, the method is carried out according to the following steps:

[0066] Step one, SiC fiber preform preparation:

[0067] A SiC fiber preform is woven on the graphite core to form a cladding tube, with a fiber line density of 0.5k, a weaving angle of 45°, a weaving thickness of 1.2mm, and a fiber volume fraction of 40%; then a layer of short SiC fiber mesh tire is wrapped on the surface of the woven body, with single-fiber form of fibers in the mesh tire, a fiber length of about 80mm, and a volume fraction of 12%; SiC short fibers are introduced into the SiC fiber preform of the cladding tube in a radial direction by using needle punching technology, with a needle punching density of 10 needles / cm 2 .

[0068] Step two, interface layer preparation:

[0069] Pyrolytic carbon interface is deposited by chemical vapor infiltration method, under the conditions of 1030℃ and 3000Pa, for about 60h, with a mixed gas of natural gas and propane as the reaction gas, and a molar ratio of 4, to prepare a pyrolytic carbon interface with a thickness of about 250nm.

[0070] Step three, first-stage SiC matrix deposition:

[0071] SiC matrix is deposited by chemical vapor infiltration method, with trichloromethylsilane as the reaction gas introduced into the reaction chamber with hydrogen as the carrier gas, a molar ratio of hydrogen to trichloromethylsilane of 10, a carrier gas hydrogen flow rate:dilution hydrogen flow rate:protective gas argon flow rate = 3:1:3, under the conditions of 1100℃ and 3000Pa, for about 300h, until the cladding density is ~1.90g / cm 3 .

[0072] Step four, ceramic slurry preparation and impregnation:

[0073] Ti3SiC2 ceramic powder with particle size of ~1.0 µm was added to a 1.2% by mass carboxymethyl cellulose sodium CMC aqueous solution, the mass ratio of Ti3SiC2 ceramic powder to CMC aqueous solution was 1.5:10, and the ceramic slurry was prepared by ball milling for 48 h.

[0074] The cladding tube with a density of ~1.90 g / cm 3 prepared in step three was immersed in the ceramic slurry, vacuumized to an air pressure in the impregnation tank below 20 kPa, and then placed in a sealed container together with the slurry after maintaining for 45 min. Inert gas was introduced to pressurize to 2.0 MPa, and the pressure was maintained for 30 min before taking out and drying.

[0075] Step five, second-stage SiC matrix deposition:

[0076] The same deposition method as in step three was adopted until the SiC f / SiC cladding tube had a density of ~2.75 g / cm 3 .

[0077] Step six, MAX phase modified SiC coating preparation:

[0078] A layer of ceramic slurry was uniformly sprayed on the surface of the SiC f / SiC cladding tube prepared in step five, and the cladding tube was placed in an oven for drying. Then step three was repeated for about 150 h until the cladding tube surface had a uniform and dense MAX modified SiC layer, and a SiC f / SiC nuclear fuel cladding tube was obtained.

[0079] Example 3:

[0080] This example gives a preparation method of a high-thermal-conductivity and high-density SiC f / SiC nuclear fuel cladding tube, as shown in the following steps: Figure 1

[0081] Step one, SiC fiber preform preparation:

[0082] A cladding tube SiC fiber preform was prepared by weaving a three-generation SiC fiber on a graphite core, with a fiber line density of 0.5 k, a weaving angle of 45°, a weaving thickness of 1.0 mm, and a fiber volume fraction of 35%. Then a layer of short SiC fiber mesh tire was wrapped on the surface of the woven body, with the fibers in the mesh tire in the form of single-fiber, a fiber length of about 70 mm, and a volume fraction of 10%. SiC short fibers were introduced radially and uniformly in the cladding tube SiC fiber preform by needle punching technology, with a needle punching density of 13 needles / cm​2 .

[0083] Step two, interface layer preparation:

[0084] Pyrolytic carbon interface was deposited by chemical vapor infiltration method, under the condition of 980℃, 4000Pa, for about 80h, the reaction gas was natural gas and propane mixed gas with a mole ratio of 4, the thickness of the prepared pyrolytic carbon interface was about 300nm.

[0085] Step three, first stage SiC matrix deposition:

[0086] SiC matrix was deposited by chemical vapor infiltration method, the reaction gas trichloromethylsilane was introduced into the reaction chamber with hydrogen as carrier gas, the mole ratio of hydrogen to trichloromethylsilane was 9, the flow rate of carrier gas hydrogen:dilution hydrogen:protective gas argon = 3:1:3, under the condition of 1000℃, 4200Pa, for about 320h to the cladding density of ~1.85g / cm 3 .

[0087] Step four, ceramic slurry preparation and impregnation:

[0088] Ti3AlC2 ceramic powder with a particle size of ~0.6µm was added to a 1.5% by mass carboxymethyl cellulose sodium CMC aqueous solution, the mass ratio of Ti3AlC2 ceramic powder to CMC aqueous solution was 2:10, and the ceramic slurry was prepared by ball milling for 24h.

[0089] The cladding tube with a density of ~1.85g / cm 3 prepared in step three was immersed in the ceramic slurry, vacuumed to an air pressure in the impregnation tank below 20kPa, and then kept for 60min, after which the cladding tube and the slurry were put into a sealed container and inert gas was introduced to pressurize to 1.5MPa, and kept for 45min before taking out and drying.

[0090] Step five, second stage SiC matrix deposition:

[0091] The deposition method was basically the same as step three, until the SiC f / SiC cladding tube density was ~2.70g / cm 3 .

[0092] Step six, MAX phase modified SiC coating preparation:

[0093] A layer of ceramic slurry was uniformly prepared on the surface of the SiC f / SiC cladding tube prepared in step five by brushing method, and then it was put into an oven for drying, and then repeated step three for about 150h, until there was a uniform and dense MAX modified SiC layer on the surface of the cladding tube, and a SiC f / SiC cladding tube was obtained.

[0094] Example 4:

[0095] This embodiment gives a high-thermal-conductivity high-density SiC f / SiC nuclear fuel cladding tube preparation method, as shown in the method is carried out according to the following steps: Figure 1

[0096] Step one, SiC fiber preform preparation:

[0097] The SiC fiber preform of the cladding tube is woven on the graphite core using the third-generation SiC fiber, and the weaving parameters are fiber line density 0.5k, weaving angle 45°, weaving thickness 1.0mm, and fiber volume fraction 40%; then a layer of short SiC fiber mesh tire is wrapped on the surface of the woven body, the fibers in the mesh tire exist in the form of single fiber, the fiber length is about 60mm, and the volume fraction is 10%; the SiC short fibers are introduced into the SiC fiber preform of the cladding tube radially uniformly by using the needle punching technology, and the needle punching density is 5 needles / cm 2 .

[0098] Step two, interface layer preparation:

[0099] Pyrolytic carbon interface is deposited by chemical vapor infiltration method, and the thickness of the prepared pyrolytic carbon interface is about 180nm under the conditions of 1010℃, 3000Pa, and reaction gas of natural gas and propane mixed gas with a molar ratio of 3, and deposition for about 80h.

[0100] Step three, first stage SiC matrix deposition:

[0101] SiC matrix is deposited by chemical vapor infiltration method, and the reaction gas trichloromethylsilane is introduced into the reaction chamber with hydrogen as the carrier gas, the molar ratio of hydrogen to trichloromethylsilane is 10, and the flow rate of the carrier gas hydrogen:dilution hydrogen:protective gas argon=3:1:3, and the cladding density is about 1.70g / cm 3 .

[0102] Step four, ceramic slurry preparation and impregnation:

[0103] SiC ceramic powder with a particle size of about 0.8µm is added to a 0.5% mass fraction carboxymethyl cellulose sodium CMC aqueous solution, the mass ratio of SiC ceramic powder to CMC aqueous solution is 2:10, and the ceramic slurry is prepared by ball milling for 48h.

[0104] The density of the ceramic slurry prepared in step three is about 1.70g / cm 3 ​The cladding tube is immersed in the ceramic slurry, vacuumized to a pressure lower than 20 kPa in the impregnation tank, and kept for 60 min. Then the cladding tube is taken out and dried.

[0105] Step five, second stage SiC matrix deposition:

[0106] The deposition method is basically the same as that in step three, until the SiC f / SiC cladding tube has a density of about 2.75 g / cm 3 .

[0107] Step six, MAX phase modified SiC coating preparation:

[0108] A ceramic slurry is uniformly prepared on the surface of the SiC f / SiC cladding tube prepared in step five. After drying in an oven, the step three is repeated for about 100 h, until a uniform and dense SiC layer is formed on the surface of the cladding tube, obtaining a SiC f / SiC nuclear cladding tube.

[0109] The high-density SiC / SiC nuclear cladding tubes obtained in examples 1 to 4 are processed to obtain test samples, and the density, porosity, thermal conductivity and hoop strength of the samples are tested, and the test data are shown in Table 1.

[0110] Table 1 Test data of examples 1 to 4

[0111]

[0112] As shown in Table 1, the mechanical properties and density of the SiC f / SiC composite material prepared by the method of the present application are significantly improved. In addition, as shown in Figure 2 、 Figure 3 and Figure 4 , the inter-fiber porosity of the SiC f / SiC composite material prepared by the method of the present application is uniformly filled with ceramic slurry, so that the density of the composite material is improved, and the thermal conductivity and hoop strength are also improved.

[0113] Comparative example 1: (without needled fibers and without ceramic slurry impregnation modification)

[0114] This comparative example gives a method for preparing a SiC f / SiC nuclear cladding tube by using a general CVI process, which specifically includes the following steps:

[0115] Step one, SiC fiber preform preparation:

[0116] A third generation SiC fiber braided cladding tube SiC fiber preform was used on the graphite core, the braiding parameters were fiber line density 0.5k, braiding angle 45°, braiding thickness 1.0mm, and fiber volume fraction 35%.

[0117] Step two, interface layer preparation:

[0118] Step two was substantially the same as that of Example 3.

[0119] Step three, first stage SiC matrix deposition:

[0120] Step three was substantially the same as that of Example 3.

[0121] Step four, ceramic slurry preparation and impregnation:

[0122] This comparative example did not have step four.

[0123] Step five, second stage SiC matrix deposition:

[0124] Step five was substantially the same as that of Example 3.

[0125] Comparative Example 2: (use of needled fiber but without ceramic slurry impregnation modification)

[0126] This comparative example gives a method for preparing a SiC / SiC cladding tube using a general CVI process combined with needling technology, which specifically comprises the following steps: f

[0127] Step one, SiC fiber preform preparation:

[0128] Step one was substantially the same as that of Example 3.

[0129] Step two, interface layer preparation:

[0130] Step two was substantially the same as that of Example 3.

[0131] Step three, first stage SiC matrix deposition:

[0132] Step three was substantially the same as that of Example 3.

[0133] Step four, ceramic slurry preparation and impregnation:

[0134] This comparative example did not have step four.

[0135] Step five, second stage SiC matrix deposition:

[0136] Step five was substantially the same as that of Example 3.

[0137] Comparative Example 3: (without needled fiber, only ceramic slurry impregnation modification) ​

[0138] The comparative example gives a method for preparing SiC / SiC nuclear cladding tube by using general CVI process combined with needle punching process and slurry impregnation f The method for preparing SiC / SiC nuclear cladding tube specifically comprises the following steps:

[0139] Step one, preparation of SiC fiber preform:

[0140] The SiC fiber preform of the cladding tube is woven on the graphite core using the third-generation SiC fiber, the weaving parameters are fiber line density 0.5k, weaving angle 45°, weaving thickness 1.0mm, and fiber volume fraction 35%.

[0141] Step two, interface layer preparation:

[0142] It is basically the same as step two of example 3.

[0143] Step three, first-stage SiC matrix deposition:

[0144] It is basically the same as step three of example 3.

[0145] Step four, ceramic slurry preparation and impregnation:

[0146] It is basically the same as step four of example 3.

[0147] Step five, second-stage SiC matrix deposition:

[0148] It is basically the same as step five of example 3.

[0149] Step six, preparation of MAX phase modified SiC coating:

[0150] It is basically the same as step six of example 3.

[0151] Table 2 Test data of comparative example 1 to comparative example 3

[0152]

[0153] Based on the comparison of comparative example 1 to comparative example 3 and example 3, from table 2, it can be seen that the use of needle punching technology alone to introduce SiC needle punching fiber in the radial direction or the use of ceramic slurry impregnation alone can effectively improve the thermal conductivity and hoop strength of SiC / SiC nuclear cladding tube, but the effect is limited. The synergistic method of introducing SiC needle punching fiber in the radial direction by using the needle punching technology of the application and ceramic slurry impregnation can significantly improve the thermal conductivity and hoop strength of SiC / SiC nuclear cladding tube.

Claims

1. A SiC f Method of producing a SiC The method comprises the following steps: Step one, SiC fiber preform preparation: A layer of SiC short fiber web is wrapped on the surface of the SiC fiber woven body, and the SiC short fiber is introduced into the SiC fiber woven body by needle punching technology, so that the SiC short fiber is uniformly distributed in the radial direction, and the SiC fiber preform is obtained; In step one, the fibers in the SiC short fiber web exist in the form of single filament fibers, the fiber length is 60-80mm, and the volume fraction is 10%-15%; Step two, interface layer preparation: A pyrolytic carbon interface layer is deposited on the SiC fiber preform prepared in step one by chemical vapor infiltration method, and a SiC fiber preform with an interface layer is obtained; Step three, first stage SiC matrix deposition: In step two, the SiC fiber preform with interface layer prepared in step one is used to deposit SiC matrix by chemical vapor infiltration method to the density of 1.7-1.9 g / cm 3 in the whole cladding tube f , obtaining a SiC f / SiC cladding tube first stage process piece; Step four, ceramic slurry preparation and impregnation: The ceramic powder is uniformly mixed with the aqueous sodium carboxymethyl cellulose solution and ball-milled to obtain a ceramic slurry. The SiC f / SiC cladding tube first stage process piece is immersed in the ceramic slurry. The impregnation tank is first vacuumed to 10-20 kPa, then pressure is maintained for 30-60 min. Subsequently, the SiC f / SiC cladding tube first stage process piece and the ceramic slurry are placed in a sealed container, inert gas is filled to pressurize to 0.8-3.0 MPa and pressure is maintained for 30-60 min. The preform is taken out and dried to obtain a slurry-impregnated cladding tube. In step four, the ceramic powder is Ti3SiC2 or Ti3AlC2; the particle size of the ceramic powder is less than 1μm; In step four, the mass fraction of the sodium carboxymethyl cellulose aqueous solution is 0.5%-1.5%, and the mass ratio of the ceramic powder to the sodium carboxymethyl cellulose aqueous solution is (1-2):10; Step five, second stage SiC matrix deposition: The SiC-based matrix is deposited on the impregnated cladding tube obtained in step four by using chemical vapor infiltration method to a density of 2.6-2.8 g / cm 3 , obtaining a SiC f / SiC cladding tube second stage process piece; Step six, MAX phase modified SiC coating preparation: SiC prepared in step five f The surface of the SiC cladding tube prepared in the second stage process is prepared with a uniformly distributed ceramic slurry, dried and then deposited with SiC by chemical vapor deposition to prepare a MAX phase modified SiC coating, obtaining a SiC f / SiC nuclear fuel cladding tube.

2. The SiC nuclear fuel cladding tube of claim 1, wherein the SiC nuclear fuel cladding tube is formed by a method comprising: f A method of manufacturing a SiC nuclear fuel cladding tube, comprising: In step one, the needle density of the needle punching technique is 5-13 needles / cm 2 .

3. The SiC as described in claim 1 f The method for preparing SiC nuclear fuel cladding tubes is characterized by, In step one, the SiC fiber woven body is woven by third-generation SiC fibers, the fiber linear density is 0.5k, the fiber weaving angle is 45°, the weaving thickness is 0.5-1.2mm, and the fiber volume fraction is 30-40%.

4. The SiC as described in claim 1 f The method for preparing SiC nuclear fuel cladding tubes is characterized by, In step two, the thickness of the pyrolytic carbon interface layer is 150-350nm.

5. The SiC as described in claim 1 f The method for preparing SiC nuclear fuel cladding tubes is characterized by, In step two, the reaction gas of the chemical vapor infiltration method is a mixed gas of natural gas and propane, and the molar ratio of the two is (3-4):1; In step two, the deposition temperature of the chemical vapor infiltration method is 1010±50℃, the furnace gas pressure is 2000-4000Pa, and the deposition time is 40-80h.

6. The SiC as described in claim 1 f The method for preparing SiC nuclear fuel cladding tubes is characterized by, In steps three and five, the reaction gas of the chemical vapor infiltration method is a mixed gas of trichloromethylsilane, hydrogen and argon, and the molar ratio of hydrogen to trichloromethylsilane is 7-10, the flow rate of the carrier gas hydrogen:diluted hydrogen:protective gas argon=3:1:3; In steps three and five, the deposition temperature of the chemical vapor infiltration method is 1050±50℃, and the furnace gas pressure is 2500-4500Pa.

7. The SiC as described in claim 1 f The method for preparing SiC nuclear fuel cladding tubes is characterized by, In step four, the ball milling process lasts for no less than 24h, and the rotation speed of the ball mill is 200-450r / min.

8. The SiC as described in claim 1 f The method for preparing SiC nuclear fuel cladding tubes is characterized by, In step six, the preparation method of the ceramic slurry comprises brushing method, spraying method or pulling and dipping method, the pulling and dipping method is prepared at a pulling speed of 2-5mm / min, and the pulling frequency is no less than 2 times; In step six, the deposition time of the chemical vapor deposition method is 100-150h.

9. A SiC f / SiC nuclear fuel cladding tube characterized by, The SiC f A SiC nuclear fuel cladding tube is made using the SiC f A method of making a SiC nuclear fuel cladding tube is made.

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