A high-temperature-resistant corrosion-resistant protective coating containing a multilayer structure and a preparation method thereof

Abstract

The application belongs to the technical field of accident tolerant fuel cladding coating, and particularly relates to a high-temperature-resistant and corrosion-resistant protective coating containing a multilayer structure and a preparation method thereof. The high-temperature-resistant and corrosion-resistant protective coating containing the multilayer structure comprises, from inside to outside, a Mo-Zr layer, a Cr-Mo layer and a metal Cr layer. The multilayer structure coating prepared by the application is uniform and dense, effectively blocks the contact between the external corrosion medium and the zirconium alloy matrix, greatly improves the stability and corrosion resistance of the zirconium alloy, and thus solves the problem of nuclear fuel leakage of the zirconium alloy cladding under the condition of loss of coolant accident.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of accident-tolerant fuel cladding coating, and particularly relates to an anti-high-temperature corrosion protective coating with a multilayer structure and a preparation method thereof. BACKGROUND

[0002] Zirconium alloy is widely used to prepare nuclear fuel cladding tubes due to its low thermal neutron absorption cross section, good thermal conductivity and moderate mechanical properties. However, under the condition of loss of coolant accident of pressurized water reactor power plant, the zirconium alloy cladding tube is rapidly oxidized and generates a large amount of hydrogen and heat, which may cause "hydrogen explosion" and lead to nuclear leakage accident.

[0003] Coating modification of the surface of zirconium alloy not only has short research and development cycle and low cost, but also does not change the traditional fuel system. Therefore, under short-term conditions, coating modification is the key to improving the high-temperature steam oxidation resistance of zirconium alloy cladding. As a candidate coating material, Cr coating is considered to be the most promising protective coating for zirconium alloy cladding due to its excellent thermal conductivity, high-temperature steam oxidation resistance, similar thermal expansion coefficient and good compatibility with zirconium alloy.

[0004] However, under the service condition of high-temperature steam environment in accident condition, serious element interdiffusion occurs in the Cr-plated cladding. On the one hand, Cr element diffuses to the zirconium matrix to form a brittle ZrCr2 layer and reduce the toughness of the coating; on the other hand, Zr element diffuses along the grain boundary of the Cr coating to the surface to preferentially react with oxygen to form ZrO2, which causes the rapid diffusion channel of oxygen in the Cr coating and further causes the destruction and failure of the coating. SUMMARY

[0005] The present application provides an anti-high-temperature corrosion protective coating with a multilayer structure and a preparation method thereof, which overcomes the deficiencies in the prior art. The protective coating with a multilayer structure has good adhesion to the substrate, smooth surface and dense structure, and excellent high-temperature steam oxidation resistance.

[0006] One object of the present application is to provide an anti-high-temperature corrosion protective coating with a multilayer structure, which comprises a Mo-Zr layer, a Cr-Mo layer and a metallic Cr layer in sequence from inside to outside.

[0007] Preferably, the Mo-Zr layer is composed of ZrMo2, the Cr-Mo layer is composed of Cr3Mo, and the metallic Cr layer is composed of Cr crystal.

[0008] Preferably, the thickness of the Mo-Zr layer is 0.3-3 μm, the thickness of the Cr-Mo layer is 0.5-5 μm, and the thickness of the metallic Cr layer is 5-20 μm.

[0009] Another object of the present application is to provide a method for preparing a high-temperature corrosion-resistant protective coating with a multi-layer structure, comprising the following steps:

[0010] The Mo coating is prepared by direct current magnetron sputtering on the zirconium alloy substrate, then the Cr coating is prepared by high-power pulsed magnetron sputtering on the Mo coating, and finally the high-temperature corrosion-resistant protective coating with a multi-layer structure is obtained after annealing treatment.

[0011] Preferably, in the above preparation method, the parameters of the direct current magnetron sputtering include: the target material is Mo, the sputtering pressure is 0.1-0.3 Pa, the bias voltage is -60 to -100 V, the sputtering power is 500-2000 W, the deposition temperature is 100-300℃, and the deposition time is 2-8 h.

[0012] The Mo coating prepared by the above parameters has a dense structure and excellent adhesion with the zirconium alloy substrate.

[0013] Preferably, in the above preparation method, the parameters of the high-power pulsed magnetron sputtering include: the target material is Cr, the sputtering pressure is 0.1-0.3 Pa, the bias voltage is -60 to -100 V, the pulse frequency is 300-600 Hz, the sputtering power is 2000-4000 W, the deposition temperature is 100-300℃, and the deposition time is 6-12 h.

[0014] Compared with the traditional direct current magnetron sputtering, the high-power pulsed magnetron sputtering technology (pulse frequency: 300-600 Hz, sputtering power: 2000-4000 W) can obtain high-density high-energy plasma under high-power pulse conditions, and the prepared coating has a smooth surface, a dense structure, and good adhesion with the Mo layer.

[0015] Preferably, the purity of the Mo target and the Cr target is more than 99.999%.

[0016] Preferably, during the magnetron sputtering process, the sample stage rotation speed is maintained at 10-30 rpm, and the distance between the target and the sample during the sputtering deposition process is 10-13 cm.

[0017] Preferably, in the above preparation method, the thickness of the sputtered Mo coating is 1-5 μm, and the thickness of the sputtered Cr coating is 8-22 μm.

[0018] The thickness of the Mo coating is controlled to be 1-5 μm, and during the subsequent annealing treatment, part of the Mo diffuses into the Zr substrate, and the remaining Mo diffuses into the Cr layer, thereby forming Mo-Zr layers and Cr-Mo layers, without residual Mo single-layer.

[0019] Preferably, before the zirconium alloy substrate is subjected to magnetron sputtering, the Mo target and the Cr target are pre-sputtered to remove oxides or adsorbed impurities on the surface of the target; the pre-sputtering power is 500-2000 W, the cavity vacuum is 1-3 Pa, and the pre-sputtering time is 5-15 min.

[0020] Preferably, in the preparation method, the zirconium alloy substrate is subjected to argon plasma etching before the Mo coating is sputtered, and the etching time is 10-30 min. The zirconium alloy substrate is subjected to plasma etching to further clean the substrate and remove surface contaminants and oxides.

[0021] Preferably, the argon plasma etching parameters include a bias voltage of -200 to -400 V, an argon flow rate of 30-60 sccm, and an ion source current of 0.1-0.3 A.

[0022] Preferably, before the zirconium alloy substrate is subjected to argon plasma etching, the substrate is subjected to pretreatment, including grinding, polishing, cleaning, etc., to remove impurities on the surface of the zirconium alloy substrate.

[0023] Preferably, in the preparation method, the annealing temperature is 800-1200℃, and the annealing time is 0.5-4 h.

[0024] Compared with the prior art, the present application has the following advantages:

[0025] 1. The protective coating of the present application comprises, from inside to outside, a Mo-Zr layer, a Cr-Mo layer and a metallic Cr layer, which is well combined with the substrate, has a smooth surface and a dense structure, is beneficial to inhibiting the serious element interdiffusion between the Cr coating and the zirconium alloy substrate, enhances the interface stability of the coating and the zirconium alloy substrate under the service condition of high-temperature steam environment in accident conditions, and improves the high-temperature steam oxidation resistance of the coating.

[0026] 2. The present application uses high-power pulsed magnetron sputtering technology to deposit a surface Cr layer, which can obtain a high-density high-energy plasma under high-power pulse conditions compared with traditional direct current magnetron sputtering, and the prepared coating has a smooth surface, a dense structure and is well combined with the Mo layer.

[0027] 3. The zirconium alloy substrate of the present application is subjected to argon plasma etching before the Mo coating is sputtered, to further clean the substrate and remove surface contaminants and oxides, thereby improving the combination of the coating and the substrate.

[0028] 4. The thickness of the sputtered Mo layer is further controlled to be 1-5 μm, and during subsequent annealing, part of the Mo diffuses into the Zr substrate, and the remaining Mo diffuses into the Cr layer, thereby forming a Mo-Zr layer and a Cr-Mo layer, without residual Mo single layer. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 Schematic diagram of the high-temperature corrosion-resistant protective coating with a multilayer structure on the surface of a zirconium alloy according to an embodiment of the present application;

[0030] Figure 2 Cross-sectional scanning electron microscope image of the high-temperature corrosion-resistant protective coating with a multilayer structure on the surface of a zirconium alloy according to Example 1 of the present application;

[0031] Figure 3 Cross-sectional scanning electron microscope image of the single-layer Cr coating on the surface of a zirconium alloy according to Comparative Example 1 of the present application. DETAILED DESCRIPTION

[0032] The technical solutions of the present application will be further described and explained with reference to specific embodiments and the accompanying drawings. It should be understood that the specific embodiments described herein are only used to help understand the present application and are not used to limit the present application. The drawings used herein are only used to better illustrate the disclosed content of the present application and do not limit the scope of protection. If not specifically stated, the raw materials used in the embodiments of the present application are all commonly used raw materials in the art, and the methods used in the embodiments are all conventional methods in the art.

[0033] Example 1

[0034] The high-temperature corrosion-resistant protective coating with a multilayer structure according to the present embodiment comprises, from inside to outside, a Mo-Zr layer, a Cr-Mo layer, and a metallic Cr layer, as shown in FIG. 1, and the preparation method is as follows. Figure 1

[0035] a. Pretreatment of the base material: Prepare a Zirlo zirconium alloy with a size of 15 mm x 10 mm x 2 mm, polish the surface using 1000#, 2000#, and 3000# water sandpaper in sequence, then perform polishing treatment, and then perform ultrasonic cleaning using acetone for 30 min, and then place it in a drying oven for drying;

[0036] b. Mounting of the base: Fix the zirconium alloy base after the above treatment on the sample table of the magnetron sputtering instrument cavity;

[0037] c. Heating of the cavity and vacuum preparation: Heat the cavity of the magnetron sputtering instrument to 200°C, and vacuum pump the cavity to 3 x 10 -3 Pa;

[0038] d. Etching of the base: Perform argon plasma glow etching of the base under the conditions of a bias voltage of -300 V, an argon gas flow rate of 40 sccm, and an ion source current of 0.2 A, and the etching time is 15 min;

[0039] ​e、Pre-sputtering: the chamber of the magnetron sputtering instrument was connected with argon, and the Mo target material and the Cr target material were pre-sputtered to remove the oxides or adsorbed impurities on the surfaces of the target materials; the pre-sputtering power was 1000 W, the vacuum degree was 2.5 Pa, and the pre-sputtering time was 15 min;

[0040] f、Sputtering Mo coating: the distance between the sample table and the Mo target material was adjusted, argon was introduced, and the direct current sputtering power supply was turned on, the Mo target material was sputtered under the conditions of a sputtering gas pressure of 0.2 Pa, a bias voltage of -80 V, a sputtering power of 1000 W, and a deposition temperature of 200 ℃, and was deposited for 3 h to obtain a zirconium alloy sample with a Mo coating, and then the sputtering was stopped; the thickness of the Mo coating was 3.21 μm.

[0041] g、Sputtering Cr coating: the distance between the sample table and the Cr target material was adjusted, argon was introduced, and the high-power pulsed sputtering power supply was turned on, the Cr target material was sputtered under the conditions of a sputtering gas pressure of 0.2 Pa, a bias voltage of -80 V, a pulse frequency of 500 Hz, a sputtering power of 3000 W, and a deposition temperature of 200 ℃, and was deposited for 8 h to obtain a zirconium alloy sample with a Cr / Mo coating, the sputtering was stopped, the thickness of the Cr coating was 12.43 μm, and the sample was taken out after the temperature was reduced to room temperature;

[0042] h、Heat treatment: the coating sample was placed in an annealing furnace, and was subjected to annealing treatment in a high vacuum (a vacuum degree of 2×10 -3 Pa) environment, at a temperature of 900 ℃ for 1 h.

[0043] After the above steps, a zirconium alloy workpiece with a surface covered with a multilayer structure protective coating was finally obtained.

[0044] Figure 2 The cross-sectional scanning electron microscope image of the zirconium alloy surface containing the multilayer structure corrosion-resistant protective coating of Example 1 of the present application can clearly show that a three-layer structure is formed on the surface of the substrate, which is a Mo-Zr layer, a Cr-Mo layer and a metal Cr layer. Figure 2 The multilayer structure coating in the above was analyzed by energy spectrum point scanning, the atomic percentage of Mo in the metal Cr layer was approximately 0, the atomic percentage of Mo in the Cr-Mo layer was about 25%, and the atomic percentage of Mo in the Mo-Zr layer was about 67%; the atomic percentage of Mo in each layer structure was much less than 95%, indicating that there was no Mo single layer residue in the multilayer structure coating. It was detected that the total thickness of the multilayer structure protective coating prepared in the present example was 15.66 μm, the thickness of the Mo-Zr layer was 1.54 μm, the thickness of the Cr-Mo layer was 2.08 μm, and the thickness of the Cr layer was 12.04 μm.

[0045] Example 2

[0046] The high-temperature resistant and corrosion resistant protective coating with a multilayer structure of the embodiment comprises, from inside to outside, a Mo-Zr layer, a Cr-Mo layer and a metal Cr layer, and is prepared by the following method.

[0047] a. Pretreatment of base material: prepare a Zirlo zirconium alloy with a size of 15 mm x 10 mm x 2 mm, polish the surface by using 1000#, 2000# and 3000# water sandpaper in sequence, then polish again, and then clean by ultrasonic cleaning with alcohol for 30 min, and then dry in a drying box after cleaning;

[0048] b. Installation of base: fix the zirconium alloy base after the above treatment on a sample table of a magnetron sputtering instrument cavity;

[0049] c. Heating of cavity and vacuum preparation: heat the cavity of the magnetron sputtering instrument to 300℃, and vacuumize the cavity to 3 x 10 -3 Pa;

[0050] d. Etching of base: etch the base by argon plasma glow under the conditions of a bias voltage of -250 V, an argon flow rate of 50 sccm and an ion source current of 0.15 A, and the etching time is 20 min;

[0051] e. Pre-sputtering: introduce argon into the cavity of the magnetron sputtering instrument, and pre-sputter the Mo target and the Cr target to remove oxides or adsorbed impurities on the surface of the target; the pre-sputtering power is 1500 W, the vacuum degree is 2.5 Pa, and the pre-sputtering time is 10 min;

[0052] f. Sputtering of Mo coating: adjust the distance between the sample table and the Mo target, introduce argon, and start a direct current sputtering power supply, sputter the Mo target under the conditions of a sputtering gas pressure of 0.3 Pa, a bias voltage of -90 V, a sputtering power of 1300 W and a deposition temperature of 300℃, deposit for 3 h to obtain a zirconium alloy sample with a Mo coating, and then stop sputtering; the thickness of the Mo coating is 4.48 μm.

[0053] g. Sputtering of Cr coating: adjust the distance between the sample table and the Cr target, introduce argon, and start a high-power sputtering power supply, sputter the Cr target under the conditions of a sputtering gas pressure of 0.3 Pa, a bias voltage of -80 V, a pulse frequency of 550 Hz, a sputtering power of 3500 W and a deposition temperature of 300℃, deposit for 7 h to obtain a zirconium alloy sample with a Cr / Mo coating, stop sputtering, the thickness of the Cr coating is 11.02 μm, and the sample is taken out after the temperature is reduced to room temperature;

[0054] h. Heat treatment: place the coating sample in an annealing furnace under high vacuum (the vacuum degree is 1 x 10 -3Pa) under the environment, the temperature is 1000℃, and the time is 1h, to obtain the multi-layer structure protective coating with smooth surface and compact structure.

[0055] After the above steps, the zirconium alloy workpiece covered with the multi-layer structure protective coating is finally obtained.

[0056] It is detected that the total thickness of the multi-layer structure protective coating prepared in the embodiment is 15.85μm, wherein the thickness of the Mo-Zr layer is 2.41μm, the thickness of the Cr-Mo layer is 3.32μm, and the thickness of the Cr layer is 10.12μm.

[0057] Example 3

[0058] The difference between Example 3 and Example 1 is that the zirconium alloy substrate in Example 3 is not subjected to argon plasma glow etching, and the other steps are the same as those in Example 1.

[0059] It is detected that the total thickness of the multi-layer structure protective coating prepared in the embodiment is 15.32μm, wherein the thickness of the Mo-Zr layer is 1.43μm, the thickness of the Cr-Mo layer is 1.92μm, and the thickness of the Cr layer is 11.97μm.

[0060] Example 4

[0061] The difference between Comparative Example 4 and Example 1 is that the step g in Comparative Example 4 is as follows: sputtering Cr coating: adjusting the distance between the sample table and the Cr target, introducing argon gas and starting the direct current sputtering power supply, sputtering the Cr target under the conditions of sputtering gas pressure of 0.2Pa, bias voltage of-80V, sputtering power of 3000W and deposition temperature of 200℃, depositing for 3.5h to obtain the zirconium alloy sample with deposited Cr / Mo coating, stopping sputtering, the thickness of the Cr coating is 12.41μm, and the sample is taken out after the temperature is reduced to room temperature.

[0062] It is detected that the total thickness of the multi-layer structure protective coating prepared in the embodiment is 15.58μm, wherein the thickness of the Mo-Zr layer is 1.53μm, the thickness of the Cr-Mo layer is 2.16μm, and the thickness of the Cr layer is 11.89μm.

[0063] Comparative Example 1

[0064] The difference between the present comparative example 1 and Example 1 is that the present comparative example 1 only prepares the zirconium alloy workpiece covered with a single layer of Cr coating, and the preparation method is as follows:

[0065] a, substrate material pretreatment: prepare a Zirlo zirconium alloy with a size of 15mm×10mm×2mm, polish the surface by using 1000#, 2000# and 3000# water sandpaper in sequence, then perform polishing treatment, and then perform ultrasonic cleaning with acetone for 30min, and then place it in a drying box for drying;

[0066] b. Substrate installation: The zirconium alloy substrate after the above processing is fixed on the sample table of the magnetron sputtering instrument cavity;

[0067] c. Cavity heating and vacuum preparation: The magnetron sputtering instrument cavity is heated to 200℃, and the cavity is vacuumed to 3x10 -3 Pa;

[0068] d. Etching substrate: The substrate is etched by argon plasma glow under the conditions of a bias voltage of -300V, an argon flow rate of 40sccm, and an ion source current of 0.2A, and the etching time is 15min;

[0069] e. Pre-sputtering: The magnetron sputtering instrument cavity is connected to argon, and the Cr target material is pre-sputtered to remove the oxides or adsorbed impurities on the surface of the target material; the pre-sputtering power is 1000W, the vacuum degree is 2.5Pa, and the pre-sputtering time is 15min;

[0070] f. Sputtering Cr coating: The distance between the sample table and the Cr target material is adjusted, argon is introduced, and a high-power sputtering power source is turned on, and the Cr target material is sputtered under the conditions of a sputtering gas pressure of 0.2Pa, a bias voltage of -80V, a pulse frequency of 500Hz, a sputtering power of 3000W, and a deposition temperature of 200℃, and the deposition is carried out for 10h to obtain a zirconium alloy sample with a deposited Cr coating. Stop sputtering, and take out the sample after the temperature decreases to room temperature.

[0071] After the above steps, a zirconium alloy workpiece with a single-layer Cr coating on the surface is finally obtained. It is detected that the thickness of the single-layer Cr coating prepared in Comparative Example 1 is 15.32μm.

[0072] Comparative Example 2

[0073] The difference between Comparative Example 2 and Example 1 is that Comparative Example 2 sputters Al2O3 on the surface of the zirconium alloy substrate, and the preparation method is as follows:

[0074] a. Substrate material pretreatment: Prepare a Zirlo zirconium alloy with a size of 15mmx10mmx2mm, polish the surface with 1000#, 2000# and 3000# water sandpaper in turn, then polish, and then ultrasonic clean it with acetone alcohol for 30min, and then dry it in a drying box;

[0075] b. Substrate installation: The zirconium alloy substrate after the above processing is fixed on the sample table of the magnetron sputtering instrument cavity;

[0076] c. Cavity heating and vacuum preparation: The magnetron sputtering instrument cavity is heated to 200℃, and the cavity is vacuumed to 3x10 -3 Pa;

[0077] d. Etching the substrate: argon plasma glow etching was performed on the substrate under the conditions of a bias voltage of-300 V, an argon flow rate of 40 sccm, and an ion source current of 0.2 A, and the etching time was 15 min;

[0078] e. Pre-sputtering: argon was introduced into the cavity of the magnetron sputtering instrument, and the Al2O3 target and the Cr target were pre-sputtered to remove the oxides or adsorbed impurities on the surfaces of the targets; the pre-sputtering power was 1000 W, the vacuum degree was 2.5 Pa, and the pre-sputtering time was 15 min;

[0079] f. Sputtering an Al2O3 coating: the distance between the sample table and the Al target was adjusted, argon and oxygen were introduced, and a direct current sputtering power source was turned on, and the Al target was sputtered under the conditions of a sputtering gas pressure of 0.2 Pa, a bias voltage of-80 V, a sputtering power of 250 W, and a deposition temperature of room temperature, and the deposition was performed for 6 h to obtain a zirconium alloy sample on which an Al2O3 coating was deposited, and then the sputtering was stopped;

[0080] g. The oxygen and Ar valves were closed, the vacuuming operation was continued, and the sample table was heated after the vacuum was pumped to 3x10 -3 Pa, and the temperature was set to 200℃;

[0081] h. Sputtering a Cr coating: the distance between the sample table and the Cr target was adjusted, argon was introduced, and a high-power pulsed sputtering power source was turned on, and the Cr target was sputtered under the conditions of a sputtering gas pressure of 0.2 Pa, a bias voltage of-80 V, a pulse frequency of 500 Hz, a sputtering power of 3000 W, and a deposition temperature of 200℃, and the deposition was performed for 8 h to obtain a zirconium alloy sample on which a Cr coating was deposited, the sputtering was stopped, the thickness of the Cr coating was 12.17 μm, and the sample was taken out after the vacuum temperature decreased to room temperature;

[0082] i. Heat treatment: the coating sample was placed in an annealing furnace, and annealing treatment was performed in a high vacuum (a vacuum degree of 2x10 -3 Pa) environment, the temperature was 900℃, and the time was 1 h.

[0083] After the above steps, a zirconium alloy workpiece on which a multilayer coating was covered on the surface was finally obtained.

[0084] Comparative Example 3

[0085] The difference between Comparative Example 3 and Example 1 is that, in step f of Comparative Example 3:

[0086] Sputtering a Mo coating: the distance between the sample table and the Mo target was adjusted, argon was introduced, and a direct current sputtering power source was turned on, and the Mo target was sputtered under the conditions of a sputtering gas pressure of 0.2 Pa, a bias voltage of-80 V, a sputtering power of 1000 W, and a deposition temperature of 200℃, and the deposition was performed for 15 h to obtain a Mo coating with a thickness of 16.25 μm.

[0087] It is found that a four-layer structure is formed on the surface of the zirconium alloy substrate, which is Mo-Zr layer, Mo layer, Cr-Mo layer and metal Cr layer respectively.

[0088] Water vapor corrosion experiment of protective coating

[0089] The Zirlo zirconium alloy substrate, the zirconium alloy workpieces with protective coating prepared in Examples 1-4 and Comparative Examples 1-3 are respectively oxidized in a water vapor environment at 1200℃ for 0.5h, and the water vapor flow is 1.5g / min. In order to ensure the accuracy of the oxidation weight gain data, the number of oxidation test samples under each parameter is not less than three each time, and the oxidation weight gain is taken as an average value. The specific detection data are shown in Table 1.

[0090] Table 1

[0091]

[0092]

[0093] As can be seen from the data in the above table, the multilayer structure protective coating prepared on the surface of the Zirlo zirconium alloy has an oxidation weight gain which is significantly lower than that of the Zirlo zirconium alloy substrate and the single-layer Cr coating sample, indicating that the multilayer structure protective coating of the present application greatly enhances the accident tolerance capability of the zirconium alloy workpiece. In addition, compared with the single-layer Cr coating sample, the multilayer structure protective coating sample does not have an obvious Zr-Cr interdiffusion layer after high-temperature steam corrosion, indicating that the multilayer structure protective coating can effectively block the interdiffusion of Zr and Cr elements at high temperature.

[0094] Aspects, embodiments, features of the present application should be considered illustrative in all aspects and not limiting the present application, and the scope of the present application is only defined by the claims. Other embodiments, modifications and uses will be apparent to those skilled in the art without departing from the spirit and scope of the claimed application.

[0095] In the preparation method of the present application, the order of each step is not limited to the order listed, and for those skilled in the art, the change of the order of each step without creative labor is also within the protection scope of the present application. In addition, two or more steps or actions can be carried out simultaneously.

[0096] It should be noted that the embodiments described herein are merely illustrative of the present application and should not be construed as limiting the scope of the present application. Those skilled in the art can make various modifications or additions to the embodiments described herein or adopt similar ways to replace them without departing from the spirit of the present application. It is not necessary or possible to describe all the embodiments herein. Any obvious changes or variations derived from the spirit of the present application are still within the scope of the present application, and any additional limitations are contrary to the spirit of the present application.

Claims

1. A high-temperature and corrosion-resistant protective coating with a multi-layer structure, characterized in that, The high-temperature and corrosion-resistant protective coating with a multi-layer structure includes, from the inside out, a Mo-Zr layer, a Cr-Mo layer, and a metallic Cr layer. The method for preparing the high-temperature and corrosion-resistant protective coating with a multi-layer structure includes the following steps: A high-temperature corrosion resistant protective coating with a multi-layer structure was obtained by DC magnetron sputtering of a Mo coating with a thickness of 1~5μm on a zirconium alloy substrate, followed by high-power pulsed magnetron sputtering of a Cr coating on the Mo coating, and annealing in a vacuum environment. The annealing temperature is 800~1200℃, and the time is 0.5~4h.

2. The high-temperature and corrosion-resistant protective coating with a multi-layer structure according to claim 1, characterized in that, The Mo-Zr layer is composed of ZrMo2, the Cr-Mo layer is composed of Cr3Mo, and the metallic Cr layer is composed of Cr crystals.

3. The high-temperature and corrosion-resistant protective coating with a multi-layer structure according to claim 1, characterized in that, The thickness of the Mo-Zr layer is 0.3~3μm, the thickness of the Cr-Mo layer is 0.5~5μm, and the thickness of the metallic Cr layer is 5~20μm.

4. The high-temperature and corrosion-resistant protective coating with a multi-layer structure according to claim 1, characterized in that, The parameters for DC magnetron sputtering include: target material is Mo, sputtering gas pressure is 0.1~0.3Pa, bias voltage is -60~-100V, sputtering power is 500~2000W, deposition temperature is 100~300℃, and deposition time is 2~8h.

5. The high-temperature and corrosion-resistant protective coating with a multi-layer structure according to claim 1, characterized in that, The parameters for high-power pulsed magnetron sputtering include: target material is Cr, sputtering gas pressure is 0.1~0.3Pa, bias voltage is -60~-100V, pulse frequency is 300~600Hz, sputtering power is 2000~4000W, deposition temperature is 100~300℃, and deposition time is 6~12h.

6. The high-temperature and corrosion-resistant protective coating with a multi-layer structure according to claim 1, characterized in that, The thickness of the sputtered Cr coating is 8~22μm.

7. The high-temperature and corrosion-resistant protective coating with a multi-layer structure according to claim 1, characterized in that, Before sputtering the Mo coating, the zirconium alloy substrate is first subjected to argon plasma etching for 10-30 minutes.

8. The high-temperature corrosion-resistant protective coating with a multi-layer structure according to claim 7, characterized in that, The parameters for the argon plasma etching include: bias voltage of -200 to -400V, argon flow rate of 30 to 60 sccm, and ion source current of 0.1 to 0.3A.

9. A method for preparing a high-temperature corrosion-resistant protective coating with a multi-layer structure as described in claim 1, characterized in that, Includes the following steps: A Mo coating with a thickness of 1~5μm was formed by DC magnetron sputtering on a zirconium alloy substrate. Then, a Cr coating was formed by high-power pulsed magnetron sputtering on the Mo coating, followed by annealing to obtain a high-temperature and corrosion-resistant protective coating with a multi-layer structure. The annealing temperature is 800~1200℃, and the time is 0.5~4h.

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