A method of manufacturing a silicon carbide-based triso composite fuel

Abstract

A manufacturing method of a silicon carbide-based TRISO composite fuel, comprising the following steps: providing SiC fibers and preparing a pyrolytic carbon interface layer on the surface of the SiC fibers, and weaving into a SiC porous woven body; preparing a SiC slurry and preparing a SiC green sheet by casting; impregnating the porous woven body with the SiC slurry, laying the porous woven body on the SiC green sheet, laying TRISO particles on the porous woven body and covering another layer of SiC green sheet to be laminated and fixed to obtain a SiC-TRISO particle composite layer, stacking the SiC-TRISO particle composite layer to a designed thickness, and hot-pressing and sintering to obtain a silicon carbide-based TRISO composite fuel product. The method can solve the problem of uneven distribution of TRISO particles in the composite fuel, prepare a composite fuel with high density and high strength, and improve the safety of the nuclear reactor fuel.

Description

Technical Field

[0001] This invention belongs to the field of nuclear power, specifically relating to a method for manufacturing a silicon carbide-based TRISO composite fuel. Background Technology

[0002] With the advancement of nuclear power technology and the promotion of civilian nuclear power, the safety of nuclear fuel has received increasing attention. TRISO (Tristructural Isotropic) fuel particles, developed with the development of high-temperature gas-cooled reactors, possess stable chemical properties and extremely high strength, capable of withstanding temperatures above 1600℃ without radioactive leakage, exhibiting excellent safety performance. Therefore, TRISO fuel particles show promising application prospects in the preparation of inert-based composite fuels such as silicon carbide-based fuels. However, in conventional sintering processes, the uniformity of TRISO fuel particle distribution is difficult to control, and aggregation of TRISO fuel particles can easily lead to localized high temperatures. Moreover, the geometric structure of fuel prepared by conventional sintering processes is limited, making it difficult to meet the technical requirements of different reactors. Therefore, providing a method for manufacturing silicon carbide-based TRISO composite fuel with a uniform TRISO fuel particle distribution has high practical value. Summary of the Invention

[0003] The purpose of this invention is to provide a method for manufacturing silicon carbide-based TRISO composite fuel, thereby achieving uniform distribution of TRISO fuel particles in the matrix.

[0004] According to an embodiment of the present invention, a method for manufacturing a silicon carbide-based TRISO composite fuel is provided, comprising the following steps:

[0005] SiC fibers are provided, a pyrolytic carbon interface layer is prepared on the surface of the SiC fibers, and they are woven into a SiC porous braid. A SiC slurry is prepared, and a SiC green sheet is obtained by casting using the SiC slurry. The SiC porous braid is impregnated in the SiC slurry and dried. The impregnated and dried SiC porous braid is laid on the SiC green sheet, TRISO particles are laid on the SiC porous braid, and a second layer of SiC green sheet is covered. The layers are then laminated to obtain a SiC-TRISO particle composite layer. The SiC-TRISO particle composite layer is repeatedly stacked to the designed thickness, dried, pressed, and then hot-pressed and sintered to obtain a finished silicon carbide-based TRISO composite fuel.

[0006] This method optimizes the distribution of TRISO particles in the matrix. The porous structure obtained through SiC fiber weaving restricts TRISO formation, eliminating uneven TRISO particle distribution that may occur in conventional sintering processes and improving fuel performance. Impregnation and curing of SiC fibers with a pyrolytic carbon interface layer on the surface enhances the mechanical properties of the composite fuel. The pyrolytic carbon interface layer forms a boundary between the SiC matrix formed by sintering SiC fiber silicon carbide slurry, improving the mobility of SiC fibers under strain and thus improving the overall strain compatibility of the composite fuel, reducing the risk of crack initiation at the interface. This method can prepare composite fuels with complex shapes and is suitable for various reactors.

[0007] Furthermore, in some embodiments, the raw material powder of the SiC slurry comprises, by weight, 80%-90% SiC powder, 10%-15% sintering aid, 0.3%-0.5% dispersant, 5%-8% binder, and 2%-5% plasticizer.

[0008] Furthermore, in some embodiments, the sintering aid includes Al2O3, Y2O3 and CaO, wherein the weight ratio of Al2O3 to (Y2O3+CaO) is 6:4-7:3, and the mass ratio of Y2O3 to CaO is 4:6-10:0.

[0009] Furthermore, in some embodiments, the SiC slurry is manufactured by mixing the raw material powder with anhydrous ethanol and ball milling it, wherein the ratio of raw material powder to anhydrous ethanol is 40ml-60ml of anhydrous ethanol per 100g of raw material powder.

[0010] Furthermore, in some embodiments, the pyrolytic carbon interface layer is prepared by chemical vapor deposition and has a thickness of 0.1-1 μm.

[0011] Furthermore, in some embodiments, the preparation of the SiC slurry further includes a degassing treatment for at least 10 minutes under a pressure ≤100Pa.

[0012] Furthermore, in some embodiments, the thickness of the single-layer SiC green sheet is 0.3mm-1mm.

[0013] Furthermore, in some embodiments, the pressing pressure during the drying and pressing process is determined by performing an integrity test on the TRISO particles.

[0014] Furthermore, in some embodiments, the sintering temperature of the finished silicon carbide TRISO composite fuel is 1700℃-1900℃, the sintering pressure is 10MPa-50MPa, and the holding time is 30min-90min.

[0015] Furthermore, in some embodiments, the sintering process is carried out in an argon atmosphere. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the manufacturing process of the SiC-TRISO particle composite layer in one embodiment.

[0017] The purpose of the above-described drawings is to provide a detailed description of the invention so that those skilled in the art can understand the technical concept of the invention, and not to limit the invention. For the sake of brevity, the above-described drawings only schematically depict the structures related to the technical features of the invention, and do not depict the complete structure and all details strictly according to actual scale. Detailed Implementation

[0018] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings.

[0019] The term "embodiment" as used herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment herein. The phrase appearing in various places in the specification does not necessarily refer to the same embodiment, nor is it limited to mutually exclusive, independent, or alternative embodiments. Those skilled in the art will understand that the embodiments herein can be combined with other embodiments without structural conflict. In the description herein, "a plurality of" means at least two.

[0020] Embodiments of the present invention provide a method for manufacturing a silicon carbide-based TRISO composite fuel to solve the problems of localized overheating and reduced efficiency caused by uneven distribution of TRISO in current inert-based composite fuels. The method includes the following steps:

[0021] First, SiC fibers are prepared and surface-treated to form a pyrolytic carbon interface layer on the SiC surface. In a preferred embodiment, the pyrolytic carbon is prepared by chemical vapor deposition, preferably with a thickness of 0.1 μm-1 μm. The SiC fibers are then woven into a structure as shown in the image. Figure 1 The porous braided body 2 shown.

[0022] Next, a SiC slurry is prepared. In a preferred embodiment, the raw material powder in the SiC slurry, by weight ratio, comprises: 80%-90% SiC powder, 10%-15% sintering aid, 0.3%-0.5% dispersant, 5%-8% binder, and 2%-5% plasticizer. In a further preferred embodiment, the sintering aid includes Al2O3, Y2O3, and CaO, wherein the weight ratio of Al2O3 to (Y2O3+CaO) is 6:4-7:3, and the mass ratio of Y2O3 to CaO is 4:6-10:0. The powder raw materials are ball-milled with anhydrous ethanol at a ratio of 40ml-60ml per 100g of powder raw materials. In a preferred embodiment, after ball milling, a degassing treatment is performed at a pressure ≤100Pa for at least 10 minutes.

[0023] The next step is to prepare SiC green wafers from a portion of the SiC slurry using a casting process. The SiC slurry is coated onto a thin film substrate using a casting machine and dried to produce SiC green wafers of 0.3mm-1mm in size.

[0024] The porous braid 2 made of SiC fibers is immersed in the remaining SiC slurry, taken out, vibrated and squeezed to remove excess slurry, and dried at 80℃-120℃ for 10min-30min.

[0025] Next, SiC green sheets are cut according to design specifications to obtain a lower substrate 1 and an upper substrate 4. A dried, impregnated SiC porous braid 2 is then laid on the lower substrate 1, and TRISO fuel particles 3 are arranged on the porous braid 2. In different embodiments, the TRISO fuel particles 3 can be laid using a mold, a robotic arm, or other devices for particle distribution. After the TRISO particles 3 reach the designed density, the upper substrate 4 is used to fix them in place. This results in a SiC-TRISO composite layer with a composite structure.

[0026] The SiC-TRISO composite layers are repeatedly stacked until a preform of the designed thickness is obtained. The preform is further dried, and then further pressed and shaped using cold isostatic pressing. The specific pressure can be determined experimentally by applying different pressures to the preform, then cutting samples to observe the integrity of the TRISO particles 3. The maximum pressure at which the TRISO particles 3 do not deform or break is the preferred pressing pressure.

[0027] The preforms were hot-pressed and sintered at a temperature of 1700℃-1900℃, a sintering pressure of 10MPa-50MPa, and a holding time of 30min-90min, with argon as the protective atmosphere, to obtain a dense silicon carbide-based TRISO composite fuel product.

[0028] After sintering, the dimensions and surface condition of the composite fuel product can be corrected by machining methods such as grinding.

[0029] In the silicon carbide-based TRISO composite fuel prepared by the method provided in the above embodiments, the porous braid 2 obtained by SiC fiber weaving can restrict the TRISO particles 3, ensuring the uniformity of TRISO particle distribution in the finished composite fuel. Simultaneously, the lower substrate 1 and upper substrate 4 made from SiC green sheets further constrain the porous braid 2 and TRISO particles 3, preventing the porous braid 2 from twisting or deforming during processing, or the TRISO particles 3 from falling off the porous braid 2. A pyrolytic carbon interface layer exists between the SiC fibers in the porous braid 2 and the SiC matrix formed by sintering the slurry, giving the SiC fibers better mobility when the composite fuel is under strain, thereby improving the overall deformation coordination of the composite fuel, reducing the risk of crack initiation at the interface, and thus improving the strength and toughness of the composite fuel. Furthermore, by adjusting the proportions of the sintering aid components to be close to the eutectic point of the multi-component mixture, it can melt at a lower temperature to form a liquid phase, wetting the SiC fibers and other powder raw materials, thereby further improving the density of the composite fuel. This method can flexibly prepare composite fuel into various required shapes according to design needs, better adapt to the fuel requirements of different nuclear reactors, and improve the safety performance of reactor fuel.

[0030] The purpose of the above embodiments is to provide a further detailed description of the present invention in conjunction with the accompanying drawings, so that those skilled in the art can understand the technical concept of the present invention. Within the scope of the present invention, optimization or equivalent substitution of the method steps involved, as well as combination of implementation methods in different embodiments without causing structural and principle conflicts, all fall within the protection scope of the present invention.

Claims

1. A method for manufacturing a silicon carbide-based TRISO composite fuel, characterized in that, Includes the following steps: SiC fibers are provided, a pyrolytic carbon interface layer is prepared on the surface of the SiC fibers, and they are woven into a porous SiC braid. Prepare a SiC slurry, and use the SiC slurry to prepare SiC green sheets by tape casting. The SiC porous braid is immersed in the SiC slurry and then dried. The impregnated and dried SiC porous braid is laid on the SiC green sheet, TRISO particles are laid on the SiC porous braid, and a second layer of SiC green sheet is covered. The layers are then laminated and fixed to obtain a SiC-TRISO particle composite layer. The SiC-TRISO particle composite layer is repeatedly stacked to the designed thickness, and then dried, pressed, and hot-pressed to form a finished silicon carbide-based TRISO composite fuel.

2. The method for manufacturing silicon carbide-based TRISO composite fuel according to claim 1, characterized in that, The raw material powder composition of the SiC slurry, by weight ratio, is 80%-90% SiC powder, 10%-15% sintering aid, 0.3%-0.5% dispersant, 5%-8% binder, and 2%-5% plasticizer.

3. The method for manufacturing silicon carbide-based TRISO composite fuel according to claim 2, characterized in that, The sintering aids include Al2O3, Y2O3 and CaO, wherein the weight ratio of Al2O3 to (Y2O3+CaO) is 6:4-7:3 and the mass ratio of Y2O3 to CaO is 4:6-10:

0.

4. The method for manufacturing silicon carbide-based TRISO composite fuel according to claim 2, characterized in that, The SiC slurry is manufactured by mixing the raw material powder with anhydrous ethanol and ball milling it. The ratio of the raw material powder to anhydrous ethanol is 40ml-60ml of anhydrous ethanol per 100g of raw material powder.

5. The method for manufacturing silicon carbide-based TRISO composite fuel according to claim 1 or 2, characterized in that, The pyrolytic carbon interface layer was prepared by chemical vapor deposition and has a thickness of 0.1-1 μm.

6. The method for manufacturing silicon carbide-based TRISO composite fuel according to claim 1 or 2, characterized in that, The preparation of the SiC slurry also includes a degassing process for at least 10 minutes under a pressure of ≤100Pa.

7. The method for manufacturing silicon carbide-based TRISO composite fuel according to claim 1 or 2, characterized in that, The thickness of a single layer of SiC green wafer is 0.3 mm to 1 mm.

8. The method for manufacturing silicon carbide-based TRISO composite fuel according to claim 1 or 2, characterized in that, The pressing pressure during the drying and pressing process is determined by performing an integrity test on the TRISO particles.

9. The method for manufacturing silicon carbide-based TRISO composite fuel according to claim 1 or 2, characterized in that, The sintering temperature of the silicon carbide-based TRISO composite fuel product is 1700℃-1900℃, the sintering pressure is 10MPa-50MPa, and the holding time is 30min-90min.

10. The method for manufacturing silicon carbide-based TRISO composite fuel according to claim 7, characterized in that, The sintering process is carried out in an argon atmosphere.

Images