CN-121674961-B - Cr-Si alloy coating for zirconium alloy surface and preparation method and application thereof

Abstract

The invention discloses a Cr-Si alloy coating for a zirconium alloy surface, and a preparation method and application thereof. The Cr-Si alloy coating comprises an in-situ diffusion barrier layer and a Cr-Si cladding layer which are sequentially formed on the surface of a zirconium alloy matrix, wherein the Cr-Si alloy coating is formed by ultra-high speed laser cladding and then high temperature vacuum annealing, the content of Si element is gradually increased in the direction from the outer surface of the Cr-Si alloy coating to the surface of the zirconium alloy matrix, the main phase of the Cr-Si cladding layer comprises a Cr 3 Si compound with an A15 type cubic system, and the in-situ diffusion barrier layer comprises a Zr 2 Si intermetallic compound. The Cr-Si alloy coating can reduce the interdiffusion among Cr-Zr atoms, slow down the reaction speed of the cladding material and water vapor at high temperature, delay the degradation process of a reactor core, and ensure that the zirconium alloy matrix has excellent high-temperature oxidation resistance and mechanical property.

Inventors

• PU JIBIN
• CUI ZHIYONG
• LIU JIAN
• PANG XUMING

Assignees

• 中国科学院宁波材料技术与工程研究所

Dates

Publication Date

20260512

Application Date

20260210

Claims (9)

1. 1. The Cr-Si alloy coating for the surface of the zirconium alloy is characterized by comprising an in-situ diffusion barrier layer and a Cr-Si cladding layer which are sequentially formed on the surface of a zirconium alloy substrate, wherein the Cr-Si alloy coating is formed by adopting ultra-high speed laser cladding to clad the surface of the zirconium alloy substrate and then carrying out high-temperature vacuum annealing treatment, the content of Si element in the Cr-Si alloy coating is 10at% to 40at%, and the content of Si element is gradually increased in the direction from the outer surface of the Cr-Si alloy coating to the surface of the zirconium alloy substrate; The main phase of the Cr-Si cladding layer comprises a Cr 3 Si compound with an A15 type cubic system, and the in-situ diffusion barrier layer comprises a Zr 2 Si intermetallic compound.
2. 2. The Cr-Si alloy coating for a zirconium alloy surface according to claim 1, wherein the grain size of the grains contained in said Cr-Si cladding layer is 5 μm or less; And/or the thickness of the Cr-Si cladding layer is 10-40 mu m; And/or the Cr 3 Si compound comprises Cr-Si solid solution, and the content of the Cr-Si solid solution in the Cr-Si cladding layer is more than 80at%.
3. 3. The Cr-Si alloy coating for a zirconium alloy surface according to claim 1, wherein the in-situ diffusion barrier layer has a thickness of 10 μm to 40 μm; And/or, after high-temperature steam oxidation, the in-situ diffusion barrier layer mainly comprises Zr 2 Si intermetallic compound and ZrCrSi intermetallic compound; and/or the zirconium alloy matrix comprises a Zr-4 alloy pipe, wherein the length of the Zr-4 alloy pipe is 100-400 mm.
4. 4. A method for preparing a Cr-Si alloy coating for a zirconium alloy surface, comprising: Providing a zirconium alloy substrate; And cladding Cr-Si alloy powder on the surface of the zirconium alloy matrix by adopting an ultra-high speed laser cladding technology, and then carrying out high-temperature vacuum annealing treatment to obtain the Cr-Si alloy coating for the surface of the zirconium alloy, wherein the Cr-Si alloy powder comprises the following components in percentage by weight of 10at% to 40at% of Si and 60at% to 90at% of Cr.
5. 5. The method according to claim 4, wherein the average particle diameter of the Cr-Si alloy powder is 5 μm or less; and/or the purity of the Cr-Si alloy powder is above 99.9at%.
6. 6. The method of claim 4, wherein the ultra-high speed laser cladding technology is characterized in that the flow rate of powder feeding gas is 5-15L/min, the laser power is 300-500W, the cladding linear speed is 10-20 m/min, the powder feeding amount is 3-4 g/min, the single-pass transverse movement is 0.4-0.6 mm, and the defocusing amount is +2-3 mm.
7. 7. The method of claim 6, wherein the high-temperature vacuum annealing treatment is performed at 900-1100 ℃ and the vacuum degree is as low as 10 -3 Pa, and the heat preservation time is 1-2 hours; And/or, the powder feeding gas comprises inert gas; And/or the preparation method further comprises polishing and cleaning the zirconium alloy matrix before cladding the Cr-Si alloy powder, wherein the cleaning comprises the step of cleaning the surface of the polished zirconium alloy matrix by adopting ethanol and/or acetone.
8. 8. Use of the Cr-Si alloy coating for zirconium alloy surfaces according to any one of claims 1 to 3 in the protection of zirconium alloy parts.
9. 9. A fuel cladding apparatus, characterized by comprising a zirconium alloy tube, the surface of which is provided with the Cr-Si alloy coating for zirconium alloy surface as claimed in any one of claims 1 to 3.

Description

Cr-Si alloy coating for zirconium alloy surface and preparation method and application thereof Technical Field The invention belongs to the technical field of accident-tolerant fuel coatings, and particularly relates to a Cr-Si alloy coating for a zirconium alloy surface, and a preparation method and application thereof. Background The safety and reliability of the nuclear power plant are very concerned, generally, the reasons for the occurrence of nuclear power accidents are mainly that cooling in a reactor is not timely under the condition of loss-of-coolant accidents (LOCA), a zirconium alloy cladding is rapidly oxidized in high-temperature vapor, so that the cladding material is invalid and releases high-concentration hydrogen, and serious explosion occurs when the cladding is hydrogen embrittled. For this reason, the nuclear industry has proposed the concept of accident tolerant fuel systems, the purpose of which is to prevent reactive nuclear accidents of zirconium alloys due to temperature transients under LOCA conditions. At present, cr coating has good prospect and advantage, but mechanical bonding and atomic diffusion between the coatings are extremely challenging to the practical applicability of the coatings. Compared with a coating prepared by a cold spraying/magnetron sputtering technology, the ultra-high-speed laser cladding technology has superior technical advantages in the aspect of zirconium alloy coating, including improving the processing speed, reducing the dilution rate, furthest reducing the thermal deformation and good metallurgical bonding. However, zr migrates into the Cr coating through grain boundaries at high temperatures and undergoes redox reactions with Cr 2O3 in the coating resulting in coating failure, such that the Zr alloy matrix is oxidized. Meanwhile, zrO 2 formed by the reaction can be obviously accumulated in the grain boundary, so that a short circuit channel is provided for oxygen to diffuse inwards, and the oxidation of the matrix is further accelerated. Disclosure of Invention The invention mainly aims to provide a Cr-Si alloy coating for the surface of a zirconium alloy and a preparation method thereof, thereby overcoming the defects in the prior art. It is another object of the present invention to provide the use of the Cr-Si alloy coating for zirconium alloy surfaces. In order to achieve the purpose of the invention, the technical scheme adopted by the invention comprises the following steps: The first aspect of the embodiment of the invention provides a Cr-Si alloy coating for a zirconium alloy surface, which comprises an in-situ diffusion barrier layer and a Cr-Si cladding layer which are sequentially formed on the zirconium alloy substrate surface, wherein the Cr-Si alloy coating is formed by adopting ultra-high speed laser cladding to clad the zirconium alloy substrate surface and then carrying out high-temperature vacuum annealing treatment, the content of Si element in the Cr-Si alloy coating is 10at% to 40at%, and the content of Si element is gradually increased in the direction from the outer surface of the Cr-Si alloy coating to the zirconium alloy substrate surface; The main phase of the Cr-Si cladding layer comprises a Cr 3 Si compound with an A15 type cubic system, and the in-situ diffusion barrier layer comprises a Zr 2 Si intermetallic compound. A second aspect of the embodiment of the present invention provides a method for preparing a cr—si alloy coating for a zirconium alloy surface, comprising: Providing a zirconium alloy substrate; And cladding Cr-Si alloy powder on the surface of the zirconium alloy matrix by adopting an ultra-high speed laser cladding technology, and then carrying out high-temperature vacuum annealing treatment to obtain the Cr-Si alloy coating for the surface of the zirconium alloy, wherein the Cr-Si alloy powder comprises the following components in percentage by weight of 10at% to 40at% of Si and 60at% to 90at% of Cr. A third aspect of the embodiments of the present invention provides a Cr-Si alloy coating for a zirconium alloy surface, prepared by the above-described preparation method. A fourth aspect of the embodiments of the present invention provides the use of the Cr-Si alloy coating for zirconium alloy surfaces in the protection of zirconium alloy parts. Accordingly, a fifth aspect of an embodiment of the present invention provides a fuel cladding apparatus comprising a zirconium alloy tube having a surface provided with a Cr-Si alloy coating as described above for a zirconium alloy surface. Compared with the prior art, the invention has the beneficial effects that: 1) The Cr-Si alloy coating is prepared on the surface of the zirconium alloy substrate by the ultra-high speed laser cladding method, and forms metallurgical bonding with the substrate, and compared with the traditional cladding, the treated zirconium alloy pipe has better high-temperature oxidation resistance; 2) According to the invention, vacuum a