Laves phase-containing layer based on control rod guide tube Cr coating and preparation method of Laves phase-containing layer

Abstract

The invention discloses a Laves phase-containing layer based on a control rod guide tube Cr coating and a preparation method of the Laves phase-containing layer, and relates to the technical field of control rod guide tube Cr coatings, the Laves phase-containing layer comprises a Laves phase-containing layer and a pure Cr coating, and the Laves phase-containing layer comprises at least two of Fe, Cr and Zr elements. The method comprises the following steps: firstly, pre-treating a zirconium alloy plate, introducing argon into a vacuum chamber, putting a base material and a target material into the vacuum chamber, adjusting parameters of high-power pulse magnetron sputtering, depositing Fe and Cr element atoms on the surface of the base material to form a Laves phase-containing layer, keeping an inert gas environment, replacing the Cr target material, depositing Cr atoms on the surface of the Laves phase-containing layer, and forming a Cr coating; diffusion between Zr and Cr elements is reduced through the Laves phase, the high-temperature oxidation resistance of the Cr coating of the control rod guide tube is improved, and the survival time of the control rod guide tube is prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of Cr coatings for control rod guide tubes, and in particular to a Laves phase-containing layer based on the Cr coatings for control rod guide tubes and a preparation method thereof. Background Art

[0002] The research on control rod guide tubes is used to improve the reliability and safety of reactor fuel systems. The control rod guide tube surface coating technology is one of the research and development goals of control rod guide tubes. Metal Cr coating is regarded as a very potential candidate material for zirconium alloy guide tube surface coating due to its high melting point, high thermal conductivity, strong resistance to high-temperature oxidation, and similar thermal expansion coefficient to zirconium alloy.

[0003] In the prior art, since the diffusion coefficient of Zr element to oxygen is relatively high, when a pure Cr coating is used, based on the mutual diffusion between Zr and Cr, after 30 minutes to 120 minutes under the loss of coolant accident (LOCA) condition, the Zr element will diffuse into the Cr coating to form an oxygen transfer channel, so that oxygen penetrates the Cr coating into the Zr matrix, causing the matrix Zr alloy in the coating to oxidize rapidly. The survival time of the control rod guide tube under the LOCA accident cannot be guaranteed, resulting in low safety of the control rod guide tube under LOCA conditions. Summary of the invention

[0004] The object of the present invention is to provide a Laves phase-containing layer based on a Cr coating of a control rod guide tube and a preparation method thereof, so as to solve the problem that the diffusion coefficient of the Zr element to oxygen is high, the coating is rapidly oxidized after 30min-120min under the condition of a loss of coolant accident, and the safety of the control rod guide tube cannot be guaranteed. The present invention selects zirconium alloy as a base material, pre-treats the zirconium alloy plate first, introduces argon gas into a vacuum chamber, puts the base material and the target material into the vacuum chamber, adjusts the parameters of high-power pulse magnetron sputtering, generates a sputtering phenomenon, and Zr, Cr, and Fe element atoms are deposited on the surface of the base material to form a Laves phase-containing layer. The inert gas environment is maintained, and the Cr target material is replaced. The sputtered Cr atoms are deposited on the surface of the Laves phase-containing layer to form a Cr coating. A layer of Laves phase-containing layer is added between the Cr coating of the control rod guide tube and the base material Zr. The Laves phase reduces the diffusion between the Zr and Cr elements, further improves the high-temperature oxidation resistance of the Cr coating of the control rod guide tube, and improves the survival time of the control rod guide tube under a LOCA accident.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solution: a Laves phase-containing layer based on a Cr coating of a control rod guide tube, comprising a Laves phase-containing layer and a pure Cr coating, wherein the Laves phase-containing layer comprises a Laves phase and a metallographic phase composed of residual Fe, Cr, and Zr elements, and the outside of the Laves phase-containing layer is arranged as a pure Cr coating.

[0006] Preferably, the metallographic phase is distributed in the coating, and the composition of the Cr coating is pure Cr metal.

[0007] Preferably, the ratio of the Laves phase in the Laves phase-containing layer is 1 to 100%, the thickness is 0.1 to 3 μm, and the thickness of the pure Cr coating is 10 to 20 μm.

[0008] A method for preparing a Laves phase-containing layer based on a Cr coating of a control rod guide tube comprises the following steps: S1. Matrix pretreatment: zirconium alloy is selected as the matrix material, and the zirconium alloy plate is cut into the matrix of the required size and shape by wire cutting technology, the surface of the matrix is ​​degreased, and the surface of the matrix is ​​polished by a metallographic grinding and polishing machine; S2. Preparation of Laves phase-containing layer: preparing a Laves phase-containing layer on a substrate material using a high-power pulsed magnetron sputtering process; S3. Preparation of pure Cr coating: A pure Cr coating is prepared on the surface of the Laves phase layer using a high-power pulsed magnetron sputtering process.

[0009] Preferably, in step S1, the degreasing treatment of the substrate surface comprises placing the zirconium alloy substrate material in acetone, alcohol solution and deionized water for ultrasonic cleaning for 15 minutes respectively.

[0010] Preferably, in step S2, the step of preparing the Laves phase-containing layer on the substrate material using a high-power pulsed magnetron sputtering process comprises the following steps: S21, introducing an inert gas into the vacuum chamber, adjusting the sputtering gas pressure of the vacuum chamber to a set value, generating a plasma gas environment, placing a target material into the vacuum chamber, wherein the target material is at least one of Cr and Fe, and using Ar ions for cleaning for 12 minutes; S22. Under the action of a high-power pulse power supply, the pulse frequency, pulse width, duty cycle and sputtering power are controlled. The target surface is bombarded by high-energy ions, resulting in sputtering. The sputtered Zr, Cr and Fe element atoms are deposited on the surface of the base material, and the deposition temperature and deposition time are controlled.

[0011] Preferably, in step S21, the sputtering gas pressure of the vacuum chamber is set to 0.2-1.5 Pa, and the bias voltage is -60--600V.

[0012] Preferably, in step S22, the pulse frequency is 200-500 Hz, the pulse width is 1-150 us, the duty cycle is 1-100%, the sputtering power is 1000-20000 W, the deposition temperature is 100-300° C., and the deposition time is 0.5-6 h.

[0013] Preferably, in step S3, the process of preparing a pure Cr coating on the surface of the Laves phase-containing layer using a high-power pulsed magnetron sputtering process comprises the following steps: S31, maintaining the previous inert gas environment and replacing the Cr target; S32. Under the action of a high-power pulse power supply, the pulse frequency, pulse width, duty cycle and sputtering power are controlled, the target surface is bombarded by high-energy ions, and the sputtered Cr atoms are deposited on the surface of the already formed Laves phase layer to form a Cr coating, and the deposition temperature and deposition time are controlled.

[0014] Preferably, in step S32, the pulse frequency is 200-500 Hz, the pulse width is 1-150 us, the duty cycle is 1-100%, the sputtering power is 1000-20000 W, the deposition temperature is 100-300° C., and the deposition time is 2-24 h.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention selects a zirconium alloy tube as a base material, pre-treats the zirconium alloy tube first, introduces argon gas into a vacuum chamber, places the base material and a target material into the vacuum chamber, adjusts the parameters of high-power pulse magnetron sputtering, generates a sputtering phenomenon, deposits Fe or Fe and Cr element atoms on the surface of the base material to form an initial coating, maintains an inert gas environment, replaces the Cr target material, and sputtered Cr atoms are deposited on the surface of the initial coating to form a Laves phase-containing layer with Fe atoms in the Fe layer and Zr atoms in the base material, and forms a Cr coating on the outer layer. A Laves phase-containing layer is added between the Cr coating of the control rod guide tube and the base material Zr, and the diffusion between the Zr and Cr elements is reduced by the Laves phase, so as to further improve the high-temperature oxidation resistance of the Cr coating of the control rod guide tube and improve the survival time of the control rod guide tube under a LOCA accident. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The present invention is a flow chart of a method for preparing a Laves phase-containing layer based on a Cr coating of a control rod guide tube. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the implementation regulations described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Example

[0018] Reference Figure 1Shown is a Laves phase-containing layer based on a Cr coating of a control rod guide tube, comprising a Laves phase-containing layer and a pure Cr coating, wherein the Laves phase-containing layer comprises a Laves phase and a metallographic phase composed of residual Fe, Cr, and Zr elements, and a pure Cr coating is arranged outside the Laves phase-containing layer.

[0019] Among them, Fe, Cr, and Zr elements are divided into two groups, one of which will form the Laves phase, and the other group is distributed in the coating as a component of the metallographic phase. The composition of the Cr coating is pure Cr metal; the proportion of the Laves phase in the Laves phase-containing layer is 25%, the thickness is 0.5μm, and the thickness of the pure Cr coating is 15μm.

[0020] A method for preparing a Laves phase-containing layer based on a Cr coating of a control rod guide tube comprises the following steps: Step 1: Matrix pretreatment: zirconium alloy is selected as the matrix material, and the zirconium alloy plate is cut into a matrix of the required size and shape by wire cutting technology, the surface of the matrix is ​​degreased, and the surface of the matrix is ​​polished by a metallographic grinder; The degreasing treatment of the substrate surface includes placing the zirconium alloy substrate material in acetone, alcohol solution and deionized water for ultrasonic cleaning for 15 minutes respectively.

[0021] Step 2: Preparation of a Laves phase-containing layer: preparing a Laves phase-containing layer on a substrate material using a high-power pulsed magnetron sputtering process; The preparation of a Laves phase-containing layer on a substrate material using a high-power pulsed magnetron sputtering process comprises the following steps: 21. Introduce inert gas into the vacuum chamber, adjust the sputtering gas pressure of the vacuum chamber to the set value, generate a plasma gas environment, place the target material into the vacuum chamber, the target material is one or both of Fe and Cr targets, and use Ar ion cleaning for 12 minutes; 22. Under the action of high-power pulse power supply, the pulse frequency, pulse width, duty cycle and sputtering power are controlled. The surface of the target material is bombarded by high-energy ions, resulting in sputtering. The sputtered Fe and Cr atoms are deposited on the surface of the base material, and the deposition temperature and deposition time are controlled.

[0022] Among them, the sputtering gas pressure of the vacuum chamber is set to 0.2Pa, the bias voltage is -200V, the pulse frequency is 350Hz, the pulse width is 100us, the duty cycle is 20%, the sputtering power is 3000W, the deposition temperature is 200℃, and the deposition time is 3h.

[0023] Step 3: Preparation of pure Cr coating: Use high-power pulsed magnetron sputtering process to prepare pure Cr coating on the surface of the Laves phase layer.

[0024] The preparation of pure Cr coating on the surface of Laves phase layer using high power pulsed magnetron sputtering process includes the following steps: 31. Maintain the previous inert gas environment and replace the Cr target; 32. Under the action of high-power pulse power supply, the pulse frequency, pulse width, duty cycle and sputtering power are controlled, the target surface is bombarded by high-energy ions, and the sputtered Cr atoms are deposited on the surface of the already formed Laves phase layer to form a Cr coating, and the deposition temperature and deposition time are controlled.

[0025] Among them, the pulse frequency is 350Hz, the pulse width is 100us, the duty cycle is 20%, the sputtering power is 3000W, the deposition temperature is 200℃, and the deposition time is 12h.

[0026] In this embodiment, by preparing a Laves phase-containing layer and a pure Cr coating, the iron element will be enriched in the Cr-Zr intermediate layer to form a Zr(Cr, Fe)2 Laves phase. The Laves phase-containing layer contains at least one of the Fe and Cr elements. This Laves phase can reduce the diffusion rate between CrZr and avoid the formation of a Cr-Zr intermediate layer, which can improve the material's antioxidant ability after 30min-120min under LOCA conditions. A high-power pulsed magnetron sputtering process is used to sequentially prepare a Laves phase-containing layer and a pure Cr coating on the substrate material. During the preparation of the Laves phase-containing layer, argon gas is introduced into the vacuum chamber, and the gas pressure of the vacuum chamber is adjusted to 0.2 Pa and the bias voltage is -200 V to obtain a plasma gas environment, which can reduce the contamination of residual gas during the sputtering process. Subsequently, a pure Cr coating is prepared on the surface of the Laves phase-containing layer. The Laves phase-containing layer has a good diffusion barrier ability for both Cr and Zr elements, and can effectively inhibit the mutual diffusion between the Cr layer and the zirconium alloy matrix material, thereby improving the high-temperature service performance of the coating. The Fe element ratio can be changed to obtain Laves phase-containing layers of different ratios. Example

[0027] Reference Figure 1 Shown is a Laves phase-containing layer based on a Cr coating of a control rod guide tube, comprising a Laves phase-containing layer and a pure Cr coating, wherein the Laves phase-containing layer comprises a Laves phase and a metallographic phase composed of residual Fe, Cr, and Zr elements, and a pure Cr coating is arranged outside the Laves phase-containing layer.

[0028] Among them, Fe, Cr, and Zr elements are divided into two groups, one of which will form the Laves phase, and the other group is distributed in the coating as a component of the metallographic phase. The composition of the Cr coating is pure Cr metal; the proportion of the Laves phase in the Laves phase layer is 5%, the thickness is 0.1μm, and the thickness of the pure Cr coating is 10μm.

[0029] In this embodiment, by preparing a Laves phase-containing layer and a pure Cr coating, the iron element will be enriched in the Cr-Zr intermediate layer to form a Zr(Cr, Fe)2 Laves phase. The Laves phase-containing layer contains at least two of the Fe, Cr, and Zr elements. This Laves phase can reduce the diffusion rate between CrZr, avoid the formation of a Cr-Zr intermediate layer, and improve the material's antioxidant ability after 30min-120min under LOCA conditions.

[0030] A method for preparing a Laves phase-containing layer based on a Cr coating of a control rod guide tube comprises the following steps: Step 1: Matrix pretreatment: zirconium alloy is selected as the matrix material, and the zirconium alloy plate is cut into a matrix of the required size and shape by wire cutting technology, the surface of the matrix is ​​degreased, and the surface of the matrix is ​​polished by a metallographic grinder; The degreasing treatment of the substrate surface includes placing the zirconium alloy substrate material in acetone, alcohol solution and deionized water for ultrasonic cleaning for 15 minutes respectively.

[0031] Step 2: Preparation of a Laves phase-containing layer: preparing a Laves phase-containing layer on a substrate material using a high-power pulsed magnetron sputtering process; The preparation of a Laves phase-containing layer on a substrate material using a high-power pulsed magnetron sputtering process comprises the following steps: 21. Introduce inert gas into the vacuum chamber, adjust the sputtering gas pressure of the vacuum chamber to the set value, generate a plasma gas environment, place the target material into the vacuum chamber, the target material is at least one of Cr and Fe, and use Ar ion cleaning for 12 minutes; 22. Under the action of high-power pulse power supply, the pulse frequency, pulse width, duty cycle and sputtering power are controlled. The surface of the target material is bombarded by high-energy ions, resulting in sputtering. The sputtered Zr, Cr, and Fe element atoms are deposited on the surface of the base material, and the deposition temperature and deposition time are controlled.

[0032] Among them, the sputtering gas pressure of the vacuum chamber is set to 0.2Pa, the bias voltage is -60V, the pulse frequency is 200Hz, the pulse width is 50us, the duty cycle is 1%, the sputtering power is 1000W, the deposition temperature is 100℃, and the deposition time is 0.5h.

[0033] Step 3: Preparation of pure Cr coating: Use high-power pulsed magnetron sputtering process to prepare pure Cr coating on the surface of the Laves phase layer.

[0034] The preparation of pure Cr coating on the surface of Laves phase layer using high power pulsed magnetron sputtering process includes the following steps: 31. Maintain the previous inert gas environment and replace the Cr target; 32. Under the action of high-power pulse power supply, the pulse frequency, pulse width, duty cycle and sputtering power are controlled, the target surface is bombarded by high-energy ions, and the sputtered Cr atoms are deposited on the surface of the already formed Laves phase layer to form a Cr coating, and the deposition temperature and deposition time are controlled.

[0035] Among them, the pulse frequency is 200 Hz, the pulse width is 50 us, the duty cycle is 1%, the sputtering power is 1000 W, the deposition temperature is 100 ° C, and the deposition time is 2 h.

[0036] The present invention selects zirconium alloy as a matrix material, first pre-treats the zirconium alloy tube, cuts the zirconium alloy tube into a matrix of a desired size and shape, places the cut matrix material in acetone, alcohol solution and deionized water for ultrasonic cleaning for 15 minutes respectively, and then uses a metallographic grinder to grind the surface of the matrix, introduces inert gas argon into a vacuum chamber, adjusts the air pressure and bias of the vacuum chamber, obtains a plasma gas environment, reduces the pollution of residual gas during sputtering, places the matrix material and the target material in the vacuum chamber, uses Ar ions for cleaning for 12 minutes to remove pollutants on the surface of the target material, adjusts the parameters of high-power pulsed magnetron sputtering, and the surface of the target material is bombarded by high-energy ions to generate a sputtering phenomenon, and Fe or Fe, Cr element atoms are deposited on the surface of the matrix material. , control the deposition temperature and deposition time to form an initial coating, the sputtered Cr atoms are deposited on the surface of the initial coating, and form a Laves phase layer with the Fe atoms in the Fe layer and the Zr atoms in the substrate, maintain an inert gas environment, replace the Cr target, adjust the parameters of high-power pulsed magnetron sputtering, the target surface is bombarded by high-energy ions, sputtering occurs, and the sputtered Cr atoms are deposited on the surface of the Laves phase layer. The deposition temperature and deposition time are controlled to form a Cr coating, and a Laves phase layer is added between the Cr coating of the control rod guide tube and the substrate material Zr. The Laves phase reduces the diffusion between the Zr and Cr elements, further improves the high-temperature oxidation resistance of the Cr coating of the control rod guide tube, and improves the survival time of the control rod guide tube under LOCA accidents.

[0037] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A Laves phase-containing layer based on a Cr coating of a control rod guide tube, characterized in that: It comprises a Laves phase-containing layer and a pure Cr coating, wherein the Laves phase-containing layer comprises a Laves phase and a metallographic phase composed of remaining Fe, Cr and Zr elements, and the outer portion of the Laves phase-containing layer is provided with a pure Cr coating.

2. The Laves phase-containing layer based on the Cr coating of the control rod guide tube according to claim 1, characterized in that: The metallographic phase is distributed in the coating, and the composition of the Cr coating is Cr pure metal.

3. The Laves phase-containing layer based on the Cr coating of the control rod guide tube according to claim 2, characterized in that: The ratio of the Laves phase in the Laves phase-containing layer is 1 to 100%, the thickness is 0.1 to 3 μm, and the thickness of the pure Cr coating is 10 to 20 μm.

4. A method for preparing a Laves phase-containing layer based on a Cr coating of a control rod guide tube, characterized in that: A Laves phase-containing layer based on a Cr coating of a control rod guide tube according to any one of claims 1 to 3 is used, comprising the following steps: S1. Matrix pretreatment: zirconium alloy is selected as the matrix material, and the zirconium alloy plate is cut into the matrix of the required size and shape by wire cutting technology, the surface of the matrix is ​​degreased, and the surface of the matrix is ​​polished by a metallographic grinding and polishing machine; S2. Preparation of Laves phase-containing layer: preparing a Laves phase-containing layer on a substrate material using a high-power pulsed magnetron sputtering process; S3. Preparation of pure Cr coating: A pure Cr coating is prepared on the surface of the Laves phase layer using a high-power pulsed magnetron sputtering process.

5. The method for preparing a Laves phase-containing layer based on a Cr coating of a control rod guide tube according to claim 4, characterized in that: In step S1, the degreasing treatment of the substrate surface includes placing the zirconium alloy substrate material in acetone, alcohol solution and deionized water for ultrasonic cleaning for 15 minutes respectively.

6. The method for preparing a Laves phase-containing layer based on a Cr coating of a control rod guide tube according to claim 4, characterized in that: In step S2, the process of preparing a Laves phase-containing layer on a substrate material using a high-power pulsed magnetron sputtering process comprises the following steps: S21, introducing an inert gas into the vacuum chamber, adjusting the sputtering gas pressure of the vacuum chamber to a set value, generating a plasma gas environment, placing a target material into the vacuum chamber, wherein the target material is at least two of Zr, Cr, and Fe, and using Ar ion cleaning for 12 minutes; S22. Under the action of a high-power pulse power supply, the pulse frequency, pulse width, duty cycle and sputtering power are controlled. The target surface is bombarded by high-energy ions, resulting in sputtering. The sputtered Zr, Cr and Fe element atoms are deposited on the surface of the base material, and the deposition temperature and deposition time are controlled.

7. The method for preparing a Laves phase-containing layer based on a Cr coating of a control rod guide tube according to claim 6, characterized in that: In step S21, the sputtering gas pressure of the vacuum chamber is set to 0.2-1.5 Pa, and the bias voltage is set to -60--600V.

8. The method for preparing a Laves phase-containing layer based on a Cr coating of a control rod guide tube according to claim 6, characterized in that: In step S22, the pulse frequency is 200-500 Hz, the pulse width is 1-150 us, the duty cycle is 1-100%, the sputtering power is 1000-20000 W, the deposition temperature is 100-300° C., and the deposition time is 0.5-6 h.

9. The method for preparing a Laves phase-containing layer based on a Cr coating of a control rod guide tube according to claim 4, characterized in that: In step S3, the process of preparing a pure Cr coating on the surface of the Laves phase-containing layer using a high-power pulsed magnetron sputtering process comprises the following steps: S31, maintaining the previous inert gas environment and replacing the Cr target; S32. Under the action of a high-power pulse power supply, the pulse frequency, pulse width, duty cycle and sputtering power are controlled, the target surface is bombarded by high-energy ions, and the sputtered Cr atoms are deposited on the surface of the already formed Laves phase layer to form a Cr coating, and the deposition temperature and deposition time are controlled.

10. The method for preparing a Laves phase-containing layer based on a Cr coating of a control rod guide tube according to claim 9, characterized in that: In step S32, the pulse frequency is 200-500 Hz, the pulse width is 1-150 us, the duty cycle is 1-100%, the sputtering power is 1000-20000 W, the deposition temperature is 100-300° C., and the deposition time is 2-24 h.

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