1. An induction heating connection method for silicon carbide cladding is characterized by comprising the following steps:

s1, adding the connecting material and the dispersing agent into an organic solvent, and performing ultrasonic dispersion to form mixed slurry;

s2, uniformly coating the mixed slurry on the connecting surface of the SiC end plug and/or the SiC cladding tube, and relatively matching the SiC end plug and the SiC cladding tube by the connecting surface to form a connecting structure;

s3, under a protective atmosphere, heating the connecting structure to 100-300 ℃, preserving heat for 0.1-4 h for solidification, and solidifying the mixed slurry between the SiC end plugs and the SiC cladding tubes to form connecting layers;

and S4, placing the connecting structure on induction heating equipment for induction heating, densifying the connecting layer, and connecting the SiC end plugs and the SiC cladding tube densely to form the SiC cladding.

2. The silicon carbide cladding induction heating joining method as set forth in claim 1, wherein in step S4, the power frequency of the induction heating is 50kHZ, the current is 100A to 1000A, and the time is 10S to 60S.

3. The silicon carbide cladding induction heating joining method of claim 1, wherein in step S1, the ratio of the dispersing agent to the joining material is 0.1wt% to 0.5 wt%: 99.9wt% -99.5 wt%.

4. The silicon carbide cladding induction heating connection method of claim 1, wherein the connection material comprises at least one of a ceramic powder, a metal powder, a glass powder, a precursor and a sintering aid;

in the connecting material, the glass powder accounts for 0-50% of the total powder mass of the glass powder and the ceramic powder, the metal powder accounts for 0-50% of the total powder mass of the ceramic powder, the glass powder and the metal powder, and the precursor accounts for 0-50% of the total powder mass of the ceramic powder, the glass powder, the metal powder and the precursor.

5. The silicon carbide cladding induction heating connection method of claim 4, wherein the ceramic powder comprises at least one of silicon carbide, zirconium carbide, titanium carbonitride and alumina, and has a powder particle size of 0.1 μm to 10 μm;

the metal powder is at least one of Ti, Zr, Nb, Ta, Cr and Ni, and the particle size of the powder is 0.1-10 mu m;

the glass powder is SiO₂-Y₂O₃-Al₂O₃、SiO₂-Y₂O₃-MgO、CaO-Al₂O₃、CaO-Al₂O₃-SiO₂At least one of (1);

the precursor is at least one of polycarbosilane, polysiloxane and polysilazane, and the ceramic yield is 60-85 wt%.

6. The silicon carbide cladding induction heating joining method of claim 4, wherein the sintering aid is present in the joining material in an amount of 1 to 10% by mass.

7. The silicon carbide cladding induction heating joining method of claim 6, wherein the sintering aid is Al₂O₃-Re₂O₃Wherein Re is Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb or Lu;

Al₂O₃and Re₂O₃The proportion of (A) is 1wt% -99 wt%: 99wt% -1 wt%.

8. The silicon carbide cladding induction heating joining method of claim 1, wherein the dispersant is at least one of oleic acid, stearic acid, castor oil;

the organic solvent is at least one of absolute ethyl alcohol, acetone, xylene and polyethylene glycol.

9. The silicon carbide cladding induction heating joining method according to any one of claims 1 to 8, wherein in step S3, the protective atmosphere is nitrogen, argon or vacuum.

10. The silicon carbide cladding induction heating joining method of any one of claims 1 to 8, wherein in step S3, the resistivity of the joining layer is 10^-1Ω•cm～10Ω•cm。

11. The silicon carbide cladding induction heating joining method according to any one of claims 1 to 8, wherein the joining layer has a thickness of 0.1 to 20 μm, a shear strength at room temperature of 60 to 100MPa, and a shear strength at a high temperature of 1200 ℃ of 80 to 150 MPa; the leakage rate of the SiC cladding is 0-1 multiplied by 10^-8 Pa·m³/s。

12. A silicon carbide cladding, characterized in that it is obtained by the silicon carbide cladding induction heating joining method of any one of claims 1 to 11.

Background

Silicon carbide (SiC) ceramic as a nuclear ceramic material has great potential to be applied to a cladding material of a reactor in the nuclear energy field, thereby making up for the defects of the current commercial zirconium alloy. However, for the application of SiC cladding, because of its high melting point and low self-diffusion coefficient, the application of SiC cladding requires a solution to the problem of the connection of the two ends. The traditional connection technology mainly adopts a sintering furnace for connection, such as a pressureless sintering furnace, a hot-pressing sintering furnace, a discharge plasma sintering furnace, a muffle furnace and the like. Although rapid connections can be achieved using resistance welding techniques, they cannot be applied to resistive connections of high purity, non-conductive SiC. For SiC materials in the nuclear field, high purity, i.e., non-conductive, is generally required, and therefore, there is an urgent need to develop a method for rapidly connecting non-conductive SiC.

Disclosure of Invention

The invention aims to provide a silicon carbide cladding induction heating connection method and a prepared silicon carbide cladding without conducting treatment on a high-purity non-conducting SiC cladding tube and an end plug.

The technical scheme adopted by the invention for solving the technical problems is as follows: the silicon carbide cladding induction heating connecting method comprises the following steps:

s1, adding the connecting material and the dispersing agent into an organic solvent, and performing ultrasonic dispersion to form mixed slurry;

s2, uniformly coating the mixed slurry on the connecting surface of the SiC end plug and/or the SiC cladding tube, and relatively matching the SiC end plug and the SiC cladding tube by the connecting surface to form a connecting structure;

s3, under a protective atmosphere, heating the connecting structure to 100-300 ℃, preserving heat for 0.1-4 h for solidification, and solidifying the mixed slurry between the SiC end plugs and the SiC cladding tubes to form connecting layers;

and S4, placing the connecting structure on induction heating equipment for induction heating, densifying the connecting layer, and connecting the SiC end plugs and the SiC cladding tube densely to form the SiC cladding.

Preferably, in step S4, the power frequency of the induction heating is 50kHZ, the current is 100A to 1000A, and the time is 10S to 60S.

Preferably, in step S1, the ratio of the dispersant to the connecting material is 0.1wt% to 0.5 wt%: 99.9wt% -99.5 wt%.

Preferably, the connecting material comprises at least one of ceramic powder, metal powder, glass powder, precursor and sintering aid;

in the connecting material, the glass powder accounts for 0-50% of the total powder mass of the glass powder and the ceramic powder, the metal powder accounts for 0-50% of the total powder mass of the ceramic powder, the glass powder and the metal powder, and the precursor accounts for 0-50% of the total powder mass of the ceramic powder, the glass powder, the metal powder and the precursor.

Preferably, the ceramic powder comprises at least one of silicon carbide, zirconium carbide, titanium carbonitride and alumina, and the particle size of the ceramic powder is 0.1-10 μm;

the metal powder is at least one of Ti, Zr, Nb, Ta, Cr and Ni, and the particle size of the powder is 0.1-10 mu m;

the glass powder is SiO₂-Y₂O₃-Al₂O₃、SiO₂-Y₂O₃-MgO、CaO-Al₂O₃、CaO-Al₂O₃-SiO₂At least one of (1);

the precursor is at least one of polycarbosilane, polysiloxane and polysilazane, and the ceramic yield is 60-85 wt%.

Preferably, the mass percentage of the sintering aid in the connecting material is 1-10%.

Preferably, the sintering aid is Al₂O₃-Re₂O₃Wherein Re is Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb or Lu;

Al₂O₃and Re₂O₃The proportion of (A) is 1wt% -99 wt%: 99wt% -1 wt%.

Preferably, the dispersant is at least one of oleic acid, stearic acid and castor oil;

the organic solvent is at least one of absolute ethyl alcohol, acetone, xylene and polyethylene glycol.

Preferably, in step S3, the protective atmosphere is nitrogen, argon or vacuum.

Preferably, in step S3, the resistivity of the connection layer is 10^-1Ω·cm～10Ω·cm。

Preferably, in step S4, the connection layer has a thickness of 0.1 to 20 μm, a shear strength of 60 to 100MPa at room temperature and a shear strength of 80 to 150MPa at a high temperature of 1200 ℃; the above-mentionedThe leakage rate of the SiC cladding is 0-1 multiplied by 10^-8Pa·m³/s。

The invention also provides a silicon carbide cladding which is obtained by the silicon carbide cladding induction heating connection method.

The invention has the beneficial effects that: the quick connection of the end plug and the cladding tube is realized by adopting an induction heating mode, so that the working time is greatly saved, and the connection efficiency is improved; the induction heating does not need to conduct electrical conduction treatment on the SiC cladding tube and the end plug which are high in purity and non-conductive, the middle connecting layer can be independently heated, nuclear fuel in the cladding can not be affected, and the reliability of the connecting part is improved.

The induction heating is adopted to realize the sealing of the two ends of the SiC cladding tube, and the SiC cladding tube can be promoted to replace the traditional zirconium alloy, so that the safety of nuclear power is improved.

Detailed Description

The invention relates to a silicon carbide cladding induction heating connection method, which comprises the following steps:

and S1, preparing mixed slurry.

The preparation method of the mixed slurry comprises the following steps: adding the connecting material and the dispersing agent into an organic solvent, and uniformly dispersing by ultrasonic to form mixed slurry.

Wherein, the proportion of the connecting material to the dispersant is 99.9wt% -99.5 wt%: 0.1wt% to 0.5 wt%. And adding a proper amount of organic solvent according to the solid content required by the mixed slurry.

The connecting material comprises at least one of ceramic powder, metal powder, glass powder, precursor and sintering aid. In the connecting material, the glass powder accounts for 0-50% of the total powder mass of the glass powder and the ceramic powder, the metal powder accounts for 0-50% of the total powder mass of the ceramic powder, the glass powder and the metal powder, and the precursor accounts for 0-50% of the total powder mass of the ceramic powder, the glass powder, the metal powder and the precursor.

Alternatively, the ceramic powder can be at least one of silicon carbide, zirconium carbide, titanium carbonitride and alumina, and the powder has a particle size of 0.1-10 μm and a purity of 99-99.999%. The glass powder is SiO₂-Y₂O₃-Al₂O₃(SiO₂、Y₂O₃And Al₂O₃Mixed powder of (2), SiO₂-Y₂O₃-MgO(SiO₂、Y₂O₃Mixed powder of MgO), CaO-Al₂O₃(CaO and Al)₂O₃Mixed powder of (2), CaO-Al₂O₃-SiO₂(CaO、Al₂O₃And SiO₂The mixed powder of (1) is used. The metal powder is at least one of Ti, Zr, Nb, Ta, Cr and Ni, the particle size of the powder is 0.1-10 μm, and the purity is 99-99.999%. The precursor is at least one of polycarbosilane, polysiloxane and polysilazane, and the ceramic yield is 60-85 wt%.

The mass percentage of the sintering aid in the connecting material is 1-10%.

The sintering aid is preferably Al₂O₃-Re₂O₃，Al₂O₃And Re₂O₃The proportion of (A) is 1wt% -99 wt%: 99wt% -1 wt%. Re₂O₃In the formula, Re is a rare earth element, and specifically may be Sc (scandium), Y (yttrium), La (lanthanum), Ce (cerium), Pr (praseodymium), Nd (neodymium), Pm (promethium), Sm (samarium), Eu (europium), Gd (gadolinium), Tb (terbium), Dy (dysprosium), Ho (holmium), Er (erbium), Tm (thulium), Yb (ytterbium), or Lu (lutetium).

The dispersant is at least one of oleic acid, stearic acid and castor oil.

The organic solvent is at least one of absolute ethyl alcohol, acetone, xylene and polyethylene glycol.

And S2, uniformly coating the mixed slurry on the connecting surface of the SiC end plug and/or the SiC cladding tube, and relatively matching the SiC end plug and the SiC cladding tube by the connecting surface to form a connecting structure.

The mixed slurry can be uniformly coated on the connecting surface of the SiC end plug or the SiC cladding tube, and then the connecting surface of the SiC end plug is opposite to the connecting surface of the SiC cladding tube and matched together to form the connecting structure. Of course, the connecting surface of the SiC end plug and the connecting surface of the SiC cladding tube may be coated with the mixed slurry, and then the two may be opposed to each other by the connecting surfaces and be mated together to form the connecting structure.

Typically, the SiC cladding tube includes a SiC cladding tube, two SiC end plugs fitted respectively on opposite ends of the SiC cladding tube. Correspondingly, in this step, two SiC end plugs were fitted on opposite ends of the SiC cladding tube, respectively, with a mixed slurry between the SiC end plugs and the SiC cladding tube.

And S3, heating the connecting structure to 100-300 ℃ in a protective atmosphere, preserving heat for 0.1-4 h for curing, and curing the mixed slurry between the SiC end plugs and the SiC cladding tubes to form a connecting layer.

The protective atmosphere is nitrogen, argon or vacuum. The resistivity of the connection layer was 10^-1Ω·cm～10Ω·cm。

And S4, placing the connecting structure on induction heating equipment for induction heating to densify the connecting layer, and connecting the SiC end plugs and the SiC cladding tube in a dense mode to form the SiC cladding.

The induction heating is also under a protective atmosphere, which may be nitrogen, argon or vacuum. On an induction heating device, the integrity of the connection is maintained by applying a suitable pressure to the connection.

The power frequency of the induction heating is 50kHZ, the current is 100A-1000A, and the time is 10 s-60 s.

The shear strength of the connecting layer with the thickness of 0.1-20 mu m is 60-100 MPa at room temperature and 80-150 MPa at high temperature of 1200 ℃.

The leakage rate of the SiC cladding obtained by the connection method is 0-1 multiplied by 10^-8Pa·m³/s。

The SiC cladding of the invention is applied to the field of nuclear radiation protection, is applied to the protection of a reactor core in a nuclear reactor, is used as a first protection barrier of the reactor core, and comprises the cladding used as a fuel pellet.

The present invention is further illustrated by the following specific examples.

Example 1

Silicon carbide powder (grain diameter 1 mu m, purity 99.99 percent) and CaO-Al₂O₃The glass powder is used as a connecting material, and the mass ratio of the silicon carbide to the glass powder is 2: 1, 0.3 wt% of castor oil is selected as the raw materialA dispersant selected from 6 wt% of Al₂O₃-Y₂O₃As sintering aid, wherein Al₂O₃And Y₂O₃The mass ratio of (A) to (B) is 3: 3. mixing silicon carbide powder, glass powder, a dispersing agent and a sintering aid according to the above proportion, carrying out ultrasonic treatment for 10min by using absolute ethyl alcohol as a solvent, and then adding a xylene solvent for ultrasonic treatment for 10min to prepare mixed slurry;

uniformly coating the mixed slurry on the surface of the SiC end plug, assembling the end plug, the connecting layer and the cladding tube, and then placing the assembled end plug, connecting layer and cladding tube into a tube furnace for curing treatment, wherein the curing process comprises the following steps: heating to 200 ℃ at a speed of 5 ℃/min under Ar protective atmosphere, then preserving heat at 200 ℃ for 2h, and then cooling along with a furnace to obtain a solidified SiC cladding and end plug connecting piece; the resistivity of the cured interlayer was measured to be 1X 10^-1And omega cm, placing the cured connecting piece on induction heating equipment, adjusting the power supply frequency to 50kHZ, regulating the equipment current to 600A, keeping for 30s, and obtaining the SiC cladding with the compact connecting layer after finishing.

In the SiC cladding, the thickness of the connecting layer is 10 μm, and the SiC cladding is subjected to shear strength test at normal temperature and high temperature of 1200 ℃ and air tightness detection. The SiC ceramic prepared in this example had a dense connecting layer, a shear strength of 100MPa at room temperature, a shear strength of 150MPa at 1200 ℃ and a leak rate of 1X 10 for the SiC cladding^-10Pa·m³/s。

Example 2

Taking metal Ti powder (with the grain diameter of 1 mu m and the purity of 99.99%) and silicon carbide powder (with the grain diameter of 0.5 mu m and the purity of 99.99%) as connecting materials, wherein the mass ratio of the metal Ti powder to the silicon carbide powder is 1: 1, the SiC cladding is connected according to the method of the embodiment 1, wherein the curing temperature is 250 ℃, the temperature is kept for 1h, the SiC cladding with a compact connecting layer is prepared by connecting under an induction heating device after curing, the current is 100A, the current is kept for 10s, and the connecting atmosphere is argon.

The SiC cladding prepared by the embodiment has a compact connecting layer, the thickness of the connecting layer is 5 μm, the shear strength at room temperature is 60MPa, the shear strength at 1200 ℃ is 80MPa, and the leakage rate of the SiC cladding is 1 x 10^-8Pa·m³/s。

Example 3

Zirconium carbide (grain diameter 10 mu m, purity 99.99%) and polycarbosilane (yield 60 wt%) are used as connecting materials, and the mass ratio of zirconium carbide powder to polycarbosilane is 1: 1, the SiC cladding is connected according to the method of the embodiment 1, wherein the curing temperature is 200 ℃, the temperature is kept for 1h, the SiC cladding with a compact connecting layer is prepared by connecting under an induction heating device after curing, the current is 1000A, the current is kept for 10s, and the connecting atmosphere is argon.

The SiC cladding prepared by the embodiment has a compact connecting layer, the thickness of the connecting layer is 10 μm, the shear strength at room temperature is 100MPa, the shear strength at 1200 ℃ and high temperature is 150MPa, and the leakage rate of the SiC cladding is 1 multiplied by 10^-11Pa·m³/s。

Example 4

Silicon carbide (particle size of 5 μm, purity of 99.99%) and metal Nb powder (particle size of 0.1 μm, purity of 99.99%) were used as connecting materials, and the mass ratio of the silicon carbide powder to the metal Nb powder was 1: 1, the SiC cladding is connected according to the method of the embodiment 1, wherein the curing temperature is 150 ℃, the temperature is kept for 4h, the SiC cladding with a compact connecting layer is prepared by connecting under an induction heating device after curing, the current is 800A, the current is kept for 10s, and the connecting atmosphere is argon.

The SiC cladding prepared by the embodiment has a compact connecting layer, the thickness of the connecting layer is 20 μm, the shear strength at room temperature is 80MPa, the shear strength at 1200 ℃ is 100MPa, and the leakage rate of the SiC cladding is 1 x 10^-10Pa·m³/s。

Example 5

Mixing silicon carbide (grain diameter 0.5 μm, purity 99.99%) and SiO₂-Y₂O₃-Al₂O₃The glass powder is used as a connecting material, and the mass ratio of the silicon carbide powder to the glass powder is 1.5: 1, the SiC cladding is connected according to the method of the embodiment 1, wherein the curing temperature is 230 ℃ and the temperature is kept for 1h, after curing, the SiC cladding with a compact connecting layer is prepared by connecting under an induction heating device, the current is 900A, the current is kept for 10s, and the connecting atmosphere is argon.

The SiC cladding prepared by the embodiment has a compact connecting layer and a thick connecting layerThe degree is 15 μm, the shear strength at room temperature is 90MPa, the shear strength at high temperature of 1200 ℃ is 120MPa, and the leakage rate of the SiC cladding is 1 x 10^-12Pa·m³/s。

The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by the present specification, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.