A method of manufacturing a double-layered cladding tube by combining an electrophoretic deposition process with a PIP process and a double-layered cladding tube

Abstract

The application discloses a method for preparing a double-layer structure cladding tube by combining an electrophoretic deposition process with a PIP process and a double-layer structure cladding tube. f The method solves the problems that zirconium alloy as a cladding material alone is high-temperature water explosion, not resistant to radiation, and SiC / SiC composite material as a cladding material alone is difficult to connect and has many pores, and on the other hand, the electrophoretic deposition process is simplified by using a zirconium alloy tube as an electrode, and the preparation cost is reduced.

Description

Technical Field

[0001] This application relates to the field of manufacturing processes for novel core-shell materials, and in particular to a method for preparing a double-layer shelled tube using an electrophoretic deposition process combined with a PIP process, and a double-layer shelled tube. Background Technology

[0002] SiC f SiC, as an emerging strategic structural ceramic material, uses SiC fibers as a second reinforcing phase to strengthen the SiC matrix. It possesses characteristics such as high specific strength, high specific modulus, high temperature resistance, radiation resistance, and good high-temperature stability. Furthermore, the introduction of SiC fibers improves the material's shortcomings, such as insufficient toughness and high crack sensitivity. SiC in high-temperature environments... f SiC composite materials exhibit minimal degradation in mechanical properties and a low coefficient of thermal expansion, preventing severe deformation at high temperatures, making them a promising next-generation nuclear reactor cladding material. Compared to Zr alloys, their advantages as nuclear reactor cladding materials primarily lie in (1) the high melting point of silicon carbide and the relatively low melting point of SiC. f The maximum operating temperature of SiC composite material can reach 2000 degrees Celsius, and the cladding will not melt due to excessive temperature, thus preventing nuclear accidents. (2) It has good high-temperature stability and will not react with water vapor to cause hydrogen explosions. (3) SiC f SiC can withstand higher operating temperatures, and the reaction can be carried out at higher temperatures than Zr alloys, improving working efficiency. (4) It has good high-temperature corrosion resistance, which can greatly improve service life and save on replacement material costs. (5) It has a low neutron absorption interface, which saves fuel under the same conditions. Therefore, SiC f SiC composite materials are superior nuclear reactor cladding materials with very high application potential. Researchers have studied SiC... f A series of studies were conducted on issues such as the low thermal conductivity of SiC composite materials, molding technology, and airtightness in order to obtain better performance. Summary of the Invention

[0003] This invention provides a method for fabricating a double-layer clad tube using electrophoretic deposition combined with PIP (Polymerization Injection) technology, and a double-layer clad tube itself. This addresses the problems of zirconium alloy exploding at high temperatures upon contact with water and its poor radiation resistance when used alone as a cladding material, as well as the issues with SiC... f When SiC composite materials are used alone as cladding materials, they are difficult to connect and have many pores. On the other hand, using zirconium alloy tubes as electrodes simplifies the electrophoretic deposition process and reduces the preparation cost.

[0004] To achieve the above objectives, this invention proposes a method for preparing a double-layer cladding tube using electrophoretic deposition combined with PIP (Polymerization Injection) process, comprising the following steps:

[0005] S1, tightly winding SiC fiber bundle on zirconium alloy pipe, forming a cladding tube preform;

[0006] S2, using SiC powder with micron or nanometer size to prepare SiC slurry with certain mass fraction;

[0007] S3, preparing a cylindrical graphite electrode with a certain inner diameter;

[0008] S4, connecting the zirconium alloy part of the cladding tube preform to the positive electrode of the electrophoresis instrument, connecting the cylindrical graphite electrode to the negative electrode of the electrophoresis instrument, and then immersing them in the SiC slurry under certain current and voltage conditions for a period of time;

[0009] S5, placing the cladding tube obtained after electrophoretic deposition into a drying box and solidifying for a period of time under certain temperature conditions;

[0010] S6, vacuum impregnating the cladding tube obtained after solidification with liquid polycarbosilane;

[0011] S7, high-temperature pyrolysis of the cladding tube obtained after vacuum impregnation;

[0012] S8, cyclic impregnation-pyrolysis until the weight gain rate of the cladding tube is reduced to 1% or less, obtaining SiC f / SiC composite material cladding tube.

[0013] The application also proposes a double-layer structure cladding tube prepared by the above method, and the tube wall of the cladding tube is zirconium alloy and SiC f / SiC composite material from inside to outside.

[0014] The application has the following beneficial effects:

[0015] The structure of the zirconium alloy inner wall combined with the SiC f / SiC composite material outer wall combines the advantages of zirconium alloy and SiC f / SiC composite material: SiC f / SiC composite material has low chemical activity, low density, low thermal expansion coefficient, high energy conversion rate, excellent high temperature strength and good corrosion resistance, which can avoid the problem of explosion of zirconium cladding at high temperature in water; at the same time, SiC f / SiC has low induced radioactivity, high dimensional stability, low induced radioactivity, low decay heat and other characteristics in nuclear radiation environment. The zirconium alloy as the inner wall solves the problems of poor connection and many pores of SiC fiber itself, and the zirconium alloy as the electrode in electrophoretic deposition can simplify the deposition process and reduce the preparation cost. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only show some of the embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from the structures shown in the drawings without any creative effort.

[0017] Figure 1 SiC cladding tube prepared by electrophoretic deposition using a graphite electrode with a diameter of 110 mm for the present application embodiment 1 f SEM image of the bonding section of the SiC / SiC composite material and the zirconium alloy;

[0018] Figure 2 SiC cladding tube prepared by electrophoretic deposition using a graphite electrode with a diameter of 70 mm for the present application embodiment 2 f SEM image of the bonding section of the SiC / SiC composite material and the zirconium alloy;

[0019] Figure 3 SiC cladding tube prepared by electrophoretic deposition using a graphite electrode with a diameter of 30 mm for the present application embodiment 3 f SEM image of the bonding section of the SiC / SiC composite material and the zirconium alloy. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without any creative effort fall within the protection scope of the present application.

[0021] In addition, the technical solutions in each of the embodiments of the present application can be combined with each other, but it must be based on the fact that a person skilled in the art can realize the combination. When the combination of technical solutions appears to be contradictory or unachievable, it should be considered that the combination of technical solutions does not exist and is not within the protection scope of the present application.

[0022] Unless otherwise specified, the materials used in the present application are commercially available.

[0023] The present application proposes a method for preparing a double-layer structure cladding tube by combining an electrophoretic deposition process with a PIP process, which comprises the following steps:

[0024] S1, tightly winding a SiC fiber bundle on a zirconium alloy pipe to form a cladding tube preform;

[0025] S2, using SiC powder with micron or nanometer size to prepare SiC slurry with certain mass fraction; the deposition liquid used in the electrophoretic deposition process is composed of SiC powder with micron or nanometer size, a suitable dispersant and deionized water, the pH value of the deposition liquid is adjusted by adding the dispersant, and the pH value is controlled in the range of 4-5 to realize the dispersion of the SiC powder.

[0026] S3, preparing a cylindrical graphite electrode with a certain inner diameter;

[0027] S4, connecting the zirconium alloy part of the cladding tube preform to the positive electrode of the electrophoresis instrument and connecting the cylindrical graphite electrode to the negative electrode of the electrophoresis instrument, and then immersing the two in the SiC slurry under certain current and voltage conditions for a period of time;

[0028] S5, placing the cladding tube obtained after electrophoretic deposition into a drying box and solidifying for a period of time under certain temperature conditions;

[0029] S6, vacuum impregnating the cladding tube obtained after solidification with liquid polycarbosilane;

[0030] S7, high-temperature pyrolysis of the cladding tube obtained after vacuum impregnation;

[0031] S8, cyclic impregnation-pyrolysis until the weight gain rate of the cladding tube is reduced to 1% or less to obtain a SiC f / SiC composite material cladding tube.

[0032] Preferably, in step S1, the number of layers of SiC fibers is not more than 3. Too many layers and too thick SiC fiber layers can easily lead to insufficient electrophoretic deposition.

[0033] Preferably, in step S1, the winding angle of the fiber bundle is 30-75° to ensure that the fibers are uniformly and closely wound on the zirconium alloy pipe.

[0034] Preferably, in step S1, the SiC fibers can be KD-I, KD-II, KD-S, KD-SA and other types of SiC fibers.

[0035] Preferably, in step S2, the particle size of the SiC powder is 30-500 nm. If the particle size is too large, SiC particles cannot enter the SiC fibers during electrophoretic deposition; if the particle size is too small, the SiC powder is not easy to disperse;

[0036] Preferably, in step S2, the mass fraction of the SiC slurry is 50-60%. If the mass fraction is too large, SiC particles are not easy to move during electrophoretic deposition and are difficult to enter the fibers; if the mass fraction is too small, the content of SiC in the electrophoretic deposition liquid is small, which can lead to insufficient deposition.

[0037] Preferably, in step S3, the inner diameter size of the cylindrical graphite electrode is greater than the outer diameter size of the cladding tube preform, and the inner diameter size is not more than 10 times the outer diameter size of the cladding tube preform. If the inner diameter is too large, the positive and negative electrodes are far apart, which can cause insufficient electrophoretic deposition. The shape of the graphite electrode is required to be cylindrical, so as to surround the cladding tube preform in the middle to form a concentric circle and ensure uniform electrophoretic deposition of the cladding tube in all directions.

[0038] Preferably, in step S3, the length of the cylindrical graphite electrode is not less than the length of the cladding tube preform, so as to ensure uniform electrophoretic deposition of the cladding tube in the length direction.

[0039] Preferably, in step S4, the current is 5-15 mA, the voltage is 5-15 V, and the electrophoretic time is 5-20 min. The voltage, current size and time length of electrophoretic deposition can not only affect the deposition effect, but also affect the mechanical properties of the SiC fiber. If the voltage and current are too small, and the electrophoretic time is too short, it is easy to cause insufficient electrophoretic deposition; if the voltage and current are too large, and the electrophoretic time is too long, the fiber will be damaged, and the mechanical properties of the fiber will decrease.

[0040] Preferably, in step S5, the curing temperature is 80-120℃, and the time is 6-8h. If the curing temperature is too low, and the time is too short, the curing efficiency will be affected; and if the curing time is too long, the preparation period will be prolonged, and the cost will be increased.

[0041] Preferably, in step S6, the impregnation time is not less than 4h. If the impregnation time is too short, the impregnation is insufficient, which affects densification.

[0042] Preferably, in step S7, the pyrolysis atmosphere is Ar environment, the pyrolysis temperature is 1200-1300℃, the heating rate is 5-10℃ / min, and the holding time is 1-2h. If the pyrolysis temperature is too high or too low, the heating rate is too fast, or the holding time is too short, the ceramic yield will be affected.

[0043] Preferably, in step S8, the number of impregnation-pyrolysis cycles is 9-15 times.

[0044] The application also provides a double-layer structure cladding tube prepared by the above method; and the wall of the cladding tube comprises, from the inside to the outside, zirconium alloy and SiCf / SiC composite material.

[0045] Example 1:

[0046] SiC f The KD-S SiC fiber is used to prepare the SiCf / SiC composite cladding tube, the winding angle of the fiber bundle is 30-75°, the angle does not need to be accurately controlled during manual winding, and the fiber can be tightly wound as long as the angle is ensured to be tight.

[0047] The slurry for electrophoretic deposition is prepared by using SiC powder with a particle size of 30nm.

[0048] The mass fraction of the slurry is controlled at 55%;

[0049] The parameters of the electrophoretic deposition are set as: current 10 mA, voltage 10 V, electrophoretic time 10 min, and a cylindrical graphite electrode is used as the negative electrode; the inner diameter of the graphite electrode is 110 mm;

[0050] The curing temperature is 120°C, and the time is 6 h;

[0051] The cladding tube is vacuum-impregnated with liquid polycarbosilane (PACS) for 8 h;

[0052] The pyrolysis atmosphere is Ar, the pyrolysis temperature is 1200°C, the heating rate is 10°C / min, and the holding time is 2 h;

[0053] The impregnation-pyrolysis cycle is 15 times.

[0054] Example 2:

[0055] SiC f The SiC / SiC composite cladding tube uses KD-S SiC fibers, the winding angle of the fiber bundle is 30-75°, manual winding is not required to precisely control the angle, and it is only required to ensure that the fibers are tightly wound;

[0056] The slurry for electrophoretic deposition is prepared using SiC powder with a particle size of 30 nm;

[0057] The mass fraction of the slurry is controlled at 55%;

[0058] The parameters of the electrophoretic deposition are set as: current 10 mA, voltage 10 V, electrophoretic time 10 min, and a cylindrical graphite electrode is used as the negative electrode; the inner diameter of the graphite electrode is 70 mm;

[0059] The curing temperature is 120°C, and the time is 6 h;

[0060] The cladding tube is vacuum-impregnated with PACS for 8 h;

[0061] The pyrolysis atmosphere is Ar, the pyrolysis temperature is 1200°C, the heating rate is 10°C / min, and the holding time is 2 h;

[0062] The impregnation-pyrolysis cycle is 15 times.

[0063] Example 3:

[0064] SiC f The SiC / SiC composite cladding tube uses KD-S SiC fibers, the winding angle of the fiber bundle is 30-75°, manual winding is not required to precisely control the angle, and it is only required to ensure that the fibers are tightly wound;

[0065] The slurry for electrophoretic deposition is prepared by using SiC powder with a particle size of 30 nm;

[0066] The mass fraction of the slurry is controlled at 55%;

[0067] The parameters for electrophoretic deposition are set as follows: current 10 mA, voltage 10 V, electrophoretic time 10 min, and a negative cylindrical graphite electrode is used, with an inner diameter of 30 mm;

[0068] The curing temperature is 120℃, and the time is 6 h;

[0069] The cladding tube is vacuum impregnated by using PACS, and the impregnation time is 8 h;

[0070] The cracking atmosphere is Ar, the cracking temperature is 1200℃, the heating rate is 10℃ / min, and the holding time is 2 h;

[0071] The impregnation-cracking cycle number is 15.

[0072] The above has described the embodiments of the present application, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for preparing a double-layer clad tube using electrophoretic deposition combined with PIP process, characterized in that, Includes the following steps: S1. Tightly wind SiC fiber bundles onto zirconium alloy tubes to form cladding tube preforms, wherein the SiC fibers are KD-S type SiC fibers and the winding angle of the fibers is 30~75°. S2. Prepare a SiC slurry with a mass fraction of 55% using SiC powder with a particle size of 30nm. S3. Prepare cylindrical graphite electrodes with an inner diameter of 30mm, 70mm or 110mm, wherein the length of the cylindrical graphite electrode is not less than the length of the cladding tube preform. S4. Connect the zirconium alloy part of the cladding tube preform to the positive electrode of the electrophoresis apparatus, and connect the cylindrical graphite electrode to the negative electrode of the electrophoresis apparatus. Then immerse both in SiC slurry and electrophores for 10 minutes under the conditions of 10mA current and 10V voltage. S5. Place the clad tube obtained after electrophoretic deposition into a drying oven and cure it at 120℃ for 6 hours. S6. Vacuum impregnation of the cured cladding tube is performed using liquid polycarbosilane for 8 hours. S7. The clad tube obtained after vacuum impregnation is subjected to high-temperature pyrolysis. The pyrolysis atmosphere is Ar, the pyrolysis temperature is 1200℃, the heating rate is 10℃ / min, and the holding time is 2h. S8, cyclic impregnation-pyrolysis 15 times, to obtain SiC f / SiC composite material clad tube.

2. A double-layer cladding tube, characterized in that, The cladding tube is prepared by the method described in claim 1; the tube wall, from the inside out, is composed of zirconium alloy and SiC. f / SiC composite material.

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