A zirconium alloy cladding composite protective coating and a method of making the same

Abstract

This invention discloses a zirconium alloy cladding composite protective coating and its preparation method, comprising a first Mo layer, a second Mo layer, and a Cr layer arranged sequentially from bottom to top. The thickness ratio of the Cr layer to the second Mo layer is (3-7):1, and the thickness ratio of the first Mo layer to the second Mo layer is (2-5):1. The morphology of the first Mo layer is nanocrystalline, and the morphology of the second Mo layer is columnar crystal. Compared with the prior art, the zirconium alloy cladding composite protective coating provided by this invention has a three-layer structure. The first Mo layer enhances the coating density, the second Mo layer is responsible for achieving strong bonding with the Cr coating, the Cr coating is responsible for achieving resistance to high-temperature water vapor corrosion and reducing the oxidation weight gain of the zirconium alloy, the first Mo layer can provide more nucleation sites, promote dense deposition of the coating, and FCC is a tightly packed lattice with a higher filling rate than BCC, resulting in better corrosion resistance.

Description

Technical Field

[0001] This invention belongs to the field of accident-tolerant fuel cladding coating technology, specifically relating to a zirconium alloy cladding composite protective coating and its preparation method. Background Technology

[0002] Zirconium alloys are widely used as core structural materials in nuclear power plants due to their low thermal neutron absorption cross-section, good thermal conductivity and mechanical properties, as well as excellent corrosion resistance in high-temperature aqueous solutions. This is because they possess characteristics such as low thermal neutron absorption cross-section, good thermal conductivity, and good mechanical properties, and also exhibit excellent corrosion resistance in high-temperature aqueous solutions. Improving the oxidation resistance of the cladding under accident conditions has become a new direction in international nuclear fuel development.

[0003] Coating technology can effectively improve the properties of substrate materials, enhancing their hardness, corrosion resistance, and resistance to high-temperature steam corrosion. It is considered the most effective and economical technology in the new era, and is of great significance for addressing the current problem of insufficient resistance to high-temperature steam corrosion in zirconium alloys used as nuclear cladding materials under loss-of-water accident conditions. Modifying the surface of zirconium alloys with coatings not only has a short development cycle and low cost, but also does not alter the traditional fuel system. Therefore, in the short term, coating technology is key to improving the high-temperature steam oxidation resistance of zirconium alloy cladding. As a candidate coating material, metallic Cr coating is considered the most promising protective coating for zirconium alloy cladding due to its excellent thermal conductivity, resistance to high-temperature steam oxidation, low thermal neutron absorption cross section, and a coefficient of thermal expansion similar to that of zirconium alloys.

[0004] However, in high-temperature steam environments, irreversible interfacial interdiffusion occurs between the Cr coating and the zirconium alloy, forming a highly brittle ZrCr2 layer. This brittle interfacial layer is prone to cracking under external forces and thermal stress, leading to coating cracking. Furthermore, during interdiffusion, Zr diffuses into the Cr coating and reacts with O to form ZrO2, creating rapid oxygen diffusion channels within the Cr coating and accelerating coating failure. Mo has a similar coefficient of thermal expansion to both zirconium alloy and Cr, allowing it to better adapt to the film-substrate synergistic deformation that may occur during high-temperature oxidation. Mo can also suppress Zr / Cr interdiffusion. However, currently studied Mo / Cr composite coatings all suffer from insufficient density, resulting in limited improvement in high-temperature steam oxidation resistance compared to Cr coatings. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a zirconium alloy cladding composite protective coating and its preparation method, which can prevent Zr / Cr interdiffusion, improve coating density, reduce the oxidation weight gain of zirconium alloy under water loss accident conditions, and improve resistance to high-temperature steam oxidation.

[0006] To achieve the above objectives, the present invention provides a zirconium alloy cladding composite protective coating, comprising a first Mo layer, a second Mo layer and a Cr layer arranged sequentially from bottom to top, wherein the thickness ratio of the Cr layer to the second Mo layer is (3-7):1, the thickness ratio of the first Mo layer to the second Mo layer is (2-5):1, the morphology of the first Mo layer is nanocrystalline, and the morphology of the second Mo layer is columnar crystal.

[0007] In this invention, the thickness ratio of the three coating layers has a crucial impact on the material's adhesion, density, and resistance to high-temperature oxidation. By adjusting the thickness ratio of the three coating layers, the density of the coating can be effectively controlled, thereby significantly improving its resistance to high-temperature oxidation.

[0008] Preferably, the Cr layer has a body-centered cubic structure with a (200) preferred orientation, a texture coefficient TC of 0.7-1.0, a grain size of 300-900 nm, and a thickness of 5-20 μm.

[0009] Preferably, the second Mo layer has a body-centered cubic structure and a thickness of 1-10 μm.

[0010] Preferably, the first Mo layer has a face-centered cubic structure and a thickness of 0.1-2 μm.

[0011] Preferably, the thickness of the zirconium alloy cladding composite protective coating is 5-30 μm.

[0012] The second objective of this invention is to provide a method for preparing a zirconium alloy cladding composite protective coating, the method specifically comprising the following steps:

[0013] S1. Pretreatment of the substrate;

[0014] S2. The substrate pretreated in step S1 is placed in a vacuum chamber, and the first Mo layer is deposited using a Mo elemental target as a magnetron sputtering target and synchronous pulse bias HIPIMS magnetron sputtering technology.

[0015] S3. Using a Mo elemental target as a magnetron sputtering target, a second Mo layer is deposited on the first Mo layer using DC magnetron sputtering technology.

[0016] S4. Using a Cr elemental target as the magnetron sputtering target, a Cr layer is deposited on the second Mo layer using synchronous pulsed bias HIPIMS magnetron sputtering technology, and finally a zirconium alloy cladding composite protective coating is obtained.

[0017] Preferably, in step S1, the pretreatment includes mechanical polishing, ultrasonic cleaning, and argon ion etching. The argon ion etching specifically includes the following steps: preheating the substrate to 100–400°C, heating the cavity temperature to 200°C, and evacuating the vacuum pressure inside the cavity to 1.0 × 10⁻⁶. -5 ~3.0×10 -5 After Torr, argon gas with a flow rate of 10-100 sccm is introduced into the cavity, the linear anodic ion source current is set to 0.1-1A, the bias voltage is -100--500V, and the substrate is argon ion etched for 10-100 min.

[0018] Preferably, in step S2, the deposition parameters of the first Mo layer are as follows: the substrate is preheated to 100-400°C, the Ar gas flow rate is 20-100 sccm, the substrate bias voltage is -10 to -200V, the pulse frequency is 100-1000Hz, the pulse width is 20-200μs, the cathode magnetron target power is 100-2500W, the discharge voltage is 100-800V, the peak current is 1-10A, the synchronous bias mode of the HiPIMS power supply is adopted, the bias power supply and the HiPIMS sputtering cathode power supply are controlled by the signal generator, the deposition time is 10-100min, and the target spacing between the substrate and the Mo elemental target is 5-30cm.

[0019] Preferably, in step S3, the deposition parameters of the second Mo layer are as follows: the substrate is preheated to 100-400°C, the Ar gas flow rate is 20-100 sccm, the substrate bias voltage is -10 to -200V, the cathode magnetron target power is 500-3000W, the discharge voltage is 200-600V, the peak current is 1-10A, the deposition time is 1-7h, and the target spacing between the substrate and the Mo elemental target is 5-30cm.

[0020] Preferably, in step S4, the deposition parameters of the Cr layer are as follows: the substrate is preheated to 100–400°C, the Ar gas flow rate is 20–100 sccm, the substrate bias voltage is -10–-200V, the pulse frequency is 100–1000Hz, the pulse width is 20–200μs, the power of the cathode magnetron target is 1000–6000W, the discharge voltage is 500–1000V, the peak current is 1–10A, the synchronous bias mode of the HiPIMS power supply is adopted, the bias power supply and the HiPIMS sputtering cathode power supply are controlled by the signal generator, the deposition time is 5–15h, and the target spacing between the substrate and the Cr elemental target is 5–30cm.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] 1. The zirconium alloy cladding composite protective coating provided by this invention has a three-layer structure. The first Mo layer (nanocrystalline) enhances the coating's density, the second Mo layer (columnar crystal) is responsible for achieving a strong bond with the Cr coating, and the Cr coating is responsible for providing resistance to high-temperature water vapor corrosion and reducing the oxidation weight gain of the zirconium alloy. The first Mo layer (nanocrystalline) provides more nucleation sites, promoting dense coating deposition. Furthermore, FCC is a tightly packed lattice with a higher filling rate than BCC, resulting in better corrosion resistance. The second Mo layer (columnar crystal) has a consistent crystal structure with the Cr layer, achieving a strong bond between the coating layers. The dense Cr coating oxidizes in a high-temperature water vapor environment to form a dense Cr2O3 layer, preventing water vapor from diffusing inward.

[0023] 2. The zirconium alloy cladding composite protective coating prepared by the technology of this invention has good uniformity, few crystal defects, and high density. During the high-temperature steam oxidation process, it inhibits Zr / Cr interdiffusion, prevents ZrO2 formation, improves the coating's resistance to high-temperature oxidation, reduces the oxidation weight gain of zirconium alloy, and achieves protection of the zirconium alloy substrate. It has broad application prospects in nuclear energy and other fields. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of the zirconium alloy cladding composite protective coating prepared in Example 1 of the present invention;

[0025] Figure 2 This is a transmission electron microscope (TEM) image of the zirconium alloy cladding composite protective coating prepared in Example 1 of the present invention.

[0026] Figure 3 This is a single-crystal diffraction pattern of the second Mo layer (columnar crystal) of the zirconium alloy cladding composite protective coating prepared in Example 1 of the present invention;

[0027] Figure 4 Selected area electron diffraction pattern of the first Mo layer (nanocrystalline) of the zirconium alloy cladding composite protective coating prepared in Example 1 of this invention;

[0028] Figure 5 The cross-sectional electron backscattering diffraction patterns are those of the zirconium alloy cladding composite protective coating prepared in Example 1 of the present invention and the composite coating prepared in Comparative Example 1.

[0029] Figure 6 The images show the XRD patterns of the zirconium alloy cladding composite protective coating prepared in Example 1 and the composite coating prepared in Comparative Example 1. Detailed Implementation

[0030] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0031] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0032] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This application specification and embodiments are merely exemplary.

[0033] The specific embodiment of the present invention lies in providing a zirconium alloy cladding composite protective coating, such as... Figure 1 As shown, it includes a first Mo layer, a second Mo layer and a Cr layer arranged sequentially from bottom to top. The thickness ratio of the Cr layer to the second Mo layer is (3-7):1, and the thickness ratio of the first Mo layer to the second Mo layer is (2-5):1. The morphology of the first Mo layer is nanocrystal and the morphology of the second Mo layer is columnar crystal.

[0034] In this invention, the thickness ratio of the three coating layers has a crucial impact on the material's adhesion, density, and resistance to high-temperature oxidation. By adjusting the thickness ratio of the three coating layers, the density of the coating can be effectively controlled, thereby significantly improving its resistance to high-temperature oxidation.

[0035] In a specific embodiment, the Cr layer has a body-centered cubic structure with a (200) preferred orientation, a texture coefficient TC of 0.7-1.0, a grain size of 300-900 nm, and a thickness of 5-20 μm.

[0036] In a specific implementation, the second Mo layer has a body-centered cubic structure and a thickness of 1-10 μm.

[0037] In a specific implementation, the first Mo layer has a face-centered cubic structure and a thickness of 0.1-2 μm.

[0038] In a specific embodiment, the thickness of the zirconium alloy cladding composite protective coating is 5-30 μm.

[0039] The second objective of this invention is to provide a method for preparing a zirconium alloy cladding composite protective coating, which specifically includes the following steps:

[0040] S1. Pretreatment of the substrate;

[0041] S2. The substrate pretreated in step S1 is placed in a vacuum chamber, and the first Mo layer is deposited using a Mo elemental target as a magnetron sputtering target and synchronous pulse bias HIPIMS magnetron sputtering technology.

[0042] S3. Using a Mo elemental target as a magnetron sputtering target, a second Mo layer is deposited on the first Mo layer using DC magnetron sputtering technology.

[0043] S4. Using a Cr elemental target as the magnetron sputtering target, a Cr layer is deposited on the second Mo layer using synchronous pulsed bias HIPIMS magnetron sputtering technology, and finally a zirconium alloy cladding composite protective coating is obtained.

[0044] In a specific embodiment, step S1 includes pretreatment comprising mechanical polishing, ultrasonic cleaning, and argon ion etching. Argon ion etching specifically includes the following steps: preheating the substrate to 100–400°C, heating the cavity temperature to 200°C, and evacuating the vacuum pressure inside the cavity to 1.0 × 10⁻⁶. -5 ~3.0×10 -5 After Torr, argon gas with a flow rate of 10-100 sccm is introduced into the cavity, the linear anodic ion source current is set to 0.1-1A, the bias voltage is -100--500V, and the substrate is argon ion etched for 10-100 min.

[0045] In a specific implementation, the deposition parameters of the first Mo layer in step S2 are as follows: the substrate is preheated to 100-400°C, the Ar gas flow rate is 20-100 sccm, the substrate bias voltage is -10 to -200V, the pulse frequency is 100-1000Hz, the pulse width is 20-200μs, the cathode magnetron target power is 100-2500W, the discharge voltage is 100-800V, the peak current is 1-10A, the synchronous bias mode of the HiPIMS power supply is adopted, the bias power supply and the HiPIMS sputtering cathode power supply are controlled by the signal generator, the deposition time is 10-100min, and the target spacing between the substrate and the Mo elemental target is 5-30cm.

[0046] In a specific implementation, the deposition parameters of the second Mo layer in step S3 are as follows: the substrate is preheated to 100-400°C, the Ar gas flow rate is 20-100 sccm, the substrate bias voltage is -10 to -200V, the cathode magnetron target power is 500-3000W, the discharge voltage is 200-600V, the peak current is 1-10A, the deposition time is 1-7h, and the target spacing between the substrate and the Mo elemental target is 5-30cm.

[0047] In a specific implementation, the deposition parameters of the Cr layer in step S4 are as follows: the substrate is preheated to 100–400°C, the Ar gas flow rate is 20–100 sccm, the substrate bias voltage is -10–-200V, the pulse frequency is 100–1000Hz, the pulse width is 20–200μs, the power of the cathode magnetron target is 1000–6000W, the discharge voltage is 500–1000V, the peak current is 1–10A, the synchronous bias mode of the HiPIMS power supply is adopted, the bias power supply and the HiPIMS sputtering cathode power supply are controlled by the signal generator, the deposition time is 5–15h, and the target spacing between the substrate and the Cr elemental target is 5–30cm.

[0048] The technical effects of the present invention will be described below with reference to specific embodiments.

[0049] Example 1

[0050] This embodiment provides a zirconium alloy cladding composite protective coating, comprising a first Mo layer, a second Mo layer, and a Cr layer arranged sequentially from bottom to top, and is prepared by the following method:

[0051] S1. The substrate undergoes mechanical polishing, ultrasonic cleaning, and argon ion etching. The argon ion etching process specifically includes the following steps: preheating the substrate to 100°C, heating the cavity to 200°C, and evacuating the vacuum pressure inside the cavity to 3.0 × 10⁻⁶. -5 After Torr, argon gas with a flow rate of 40 sccm is introduced into the cavity, the linear anodic ion source current is set to 0.2A, the bias voltage is -300V, and the substrate is argon ion etched for 30 minutes.

[0052] S2. The substrate pretreated in step S1 is placed in a vacuum chamber. Using a Mo elemental target as the magnetron sputtering target, the first Mo layer is deposited using synchronous pulsed bias HIPIMS magnetron sputtering technology. Specifically, the substrate is preheated to 200°C, the Ar gas flow rate is 50 sccm, the substrate bias voltage is -80V, the pulse frequency is 500Hz, the pulse width is 100μs, the cathode magnetron target power is 700W, the discharge voltage is 370V, the peak current is 2A, the synchronous bias mode of the HiPIMS power supply is used, the bias power supply and the HiPIMS sputtering cathode power supply are controlled by the signal generator, the deposition time is 30min, and the target spacing between the substrate and the Mo elemental target is 12cm.

[0053] S3. Using a Mo elemental target as the magnetron sputtering target, a second Mo layer is deposited on the first Mo layer using DC magnetron sputtering technology. Specifically, the substrate is preheated to 200℃, the Ar gas flow rate is 50 sccm, the substrate bias voltage is -80V, the cathode magnetron target power is 700W, the discharge voltage is 380V, the peak current is 1.9A, the deposition time is 170min, and the target spacing between the substrate and the Mo elemental target is 12cm.

[0054] S4. Using a Cr elemental target as the magnetron sputtering target, a Cr layer was deposited on the second Mo layer using synchronous pulsed bias HIPIMS magnetron sputtering technology. Specifically, the substrate was preheated to 200℃, the Ar gas flow rate was 50 sccm, the substrate bias voltage was -80V, the pulse frequency was 500Hz, the pulse width was 100μs, the power of the cathode magnetron target was 3000W, the discharge voltage was 800V, the peak current was 4A, the synchronous bias mode of the HiPIMS power supply was used, the bias power supply and the HiPIMS sputtering cathode power supply were controlled by the signal generator, the deposition time was 7h, and the target spacing between the substrate and the Cr elemental target was 12cm, finally obtaining a zirconium alloy cladding composite protective coating.

[0055] Example 2

[0056] This embodiment provides a zirconium alloy cladding composite protective coating, comprising a first Mo layer, a second Mo layer, and a Cr layer arranged sequentially from bottom to top, and is prepared by the following method:

[0057] S1. The substrate undergoes mechanical polishing, ultrasonic cleaning, and argon ion etching. The argon ion etching process specifically includes the following steps: preheating the substrate to 200°C, and then heating the cavity to 200°C while simultaneously evacuating the vacuum pressure inside the cavity to 1.0 × 10⁻⁶. -5 After Torr, argon gas with a flow rate of 10 sccm is introduced into the cavity, the linear anodic ion source current is set to 0.1A, the bias voltage is -100V, and the substrate is argon ion etched for 10 min.

[0058] S2. The substrate pretreated in step S1 is placed in a vacuum chamber. A Mo elemental target is used as the magnetron sputtering target. The first Mo layer is deposited using synchronous pulsed bias HIPIMS magnetron sputtering technology. Specifically, the substrate is preheated to 100°C, the Ar gas flow rate is 20 sccm, the substrate bias voltage is -10V, the pulse frequency is 100Hz, the pulse width is 20μs, the cathode magnetron target power is 100W, the discharge voltage is 100V, the peak current is 1A, the synchronous bias mode of the HiPIMS power supply is used, the bias power supply and the HiPIMS sputtering cathode power supply are controlled by the signal generator, the deposition time is 10min, and the target spacing between the substrate and the Mo elemental target is 5cm.

[0059] S3. Using a Mo elemental target as the magnetron sputtering target, a second Mo layer is deposited on the first Mo layer using DC magnetron sputtering technology. Specifically, the substrate is preheated to 100°C, the Ar gas flow rate is 20 sccm, the substrate bias voltage is -10V, the cathode magnetron target power is 500W, the discharge voltage is 200V, the peak current is 1A, the deposition time is 1h, and the target spacing between the substrate and the Mo elemental target is 5cm.

[0060] S4. Using a Cr elemental target as the magnetron sputtering target, a Cr layer was deposited on the second Mo layer using synchronous pulsed bias HIPIMS magnetron sputtering technology. Specifically, the substrate was preheated to 100℃, the Ar gas flow rate was 20 sccm, the substrate bias voltage was -10V, the pulse frequency was 100~1000Hz, the pulse width was 20μs, the power of the cathode magnetron target was 1000W, the discharge voltage was 500V, the peak current was 1A, the synchronous bias mode of the HiPIMS power supply was used, the bias power supply and the HiPIMS sputtering cathode power supply were controlled by the signal generator, the deposition time was 5h, and the target spacing between the substrate and the Cr elemental target was 5cm. Finally, a zirconium alloy cladding composite protective coating was obtained.

[0061] Example 3

[0062] This embodiment provides a zirconium alloy cladding composite protective coating, comprising a first Mo layer, a second Mo layer, and a Cr layer arranged sequentially from bottom to top, and is prepared by the following method:

[0063] S1. The substrate undergoes mechanical polishing, ultrasonic cleaning, and argon ion etching. The argon ion etching process specifically includes the following steps: preheating the substrate to 200°C, and then heating the cavity to 200°C while simultaneously evacuating the vacuum pressure inside the cavity to 1.5 × 10⁻⁶. -5 After Torr, argon gas with a flow rate of 20 sccm is introduced into the cavity, the linear anodic ion source current is set to 0.3A, the bias voltage is -200V, and the substrate is argon ion etched for 20 minutes.

[0064] S2. The pretreated substrate from step S1 is placed in a vacuum chamber. Using a Mo elemental target as the magnetron sputtering target, the first Mo layer is deposited using synchronous pulsed bias HIPIMS magnetron sputtering technology. Specifically, the substrate is preheated to 200°C, the Ar gas flow rate is 40 sccm, the substrate bias voltage is -50V, the pulse frequency is 300Hz, the pulse width is 60μs, the cathode magnetron target power is 500W, the discharge voltage is 200V, the peak current is 3A, the synchronous bias mode of the HiPIMS power supply is used, the bias power supply and the HiPIMS sputtering cathode power supply are controlled by the signal generator, the deposition time is 20min, and the target spacing between the substrate and the Mo elemental target is 10cm.

[0065] S3. Using a Mo elemental target as the magnetron sputtering target, a second Mo layer is deposited on the first Mo layer using DC magnetron sputtering technology. Specifically, the substrate is preheated to 300℃, the Ar gas flow rate is 50 sccm, the substrate bias voltage is -80V, the cathode magnetron target power is 2000W, the discharge voltage is 400V, the peak current is 5A, the deposition time is 3h, and the target spacing between the substrate and the Mo elemental target is 5cm.

[0066] S4. Using a Cr elemental target as the magnetron sputtering target, a Cr layer was deposited on the second Mo layer using synchronous pulsed bias HIPIMS magnetron sputtering technology. Specifically, the substrate was preheated to 300℃, the Ar gas flow rate was 80 sccm, the substrate bias voltage was -80V, the pulse frequency was 300Hz, the pulse width was 100μs, the power of the cathode magnetron target was 4000W, the discharge voltage was 700V, the peak current was 5A, the synchronous bias mode of the HiPIMS power supply was used, the bias power supply and the HiPIMS sputtering cathode power supply were controlled by the signal generator, the deposition time was 9h, and the target spacing between the substrate and the Cr elemental target was 15cm, finally obtaining a zirconium alloy cladding composite protective coating.

[0067] Example 4

[0068] This embodiment provides a zirconium alloy cladding composite protective coating, comprising a first Mo layer, a second Mo layer, and a Cr layer arranged sequentially from bottom to top, and is prepared by the following method:

[0069] S1. The substrate undergoes mechanical polishing, ultrasonic cleaning, and argon ion etching. The argon ion etching process specifically includes the following steps: preheating the substrate to 300°C, heating the cavity to 200°C, and evacuating the vacuum pressure inside the cavity to 2.5 × 10⁻⁶. -5 After Torr, argon gas with a flow rate of 80 sccm is introduced into the cavity, the linear anodic ion source current is set to 0.8A, the bias voltage is -400V, and the substrate is argon ion etched for 80 min.

[0070] S2. The pretreated substrate from step S1 is placed in a vacuum chamber. Using a Mo elemental target as the magnetron sputtering target, the first Mo layer is deposited using synchronous pulsed bias HIPIMS magnetron sputtering technology. Specifically, the substrate is preheated to 300V, the Ar gas flow rate is 80sccm, the substrate bias is -150V, the pulse frequency is 800Hz, the pulse width is 180μs, the cathode magnetron target power is 2000W, the discharge voltage is 700V, the peak current is 8A, the synchronous bias mode of the HiPIMS power supply is used, the bias power supply and the HiPIMS sputtering cathode power supply are controlled by the signal generator, the deposition time is 80min, and the target spacing between the substrate and the Mo elemental target is 25cm.

[0071] S3. Using a Mo elemental target as the magnetron sputtering target, a second Mo layer is deposited on the first Mo layer using DC magnetron sputtering technology. Specifically, the substrate is preheated to 300℃, the Ar gas flow rate is 80 sccm, the substrate bias voltage is -150V, the cathode magnetron target power is 2800W, the discharge voltage is 500V, the peak current is 8A, the deposition time is 6h, and the target spacing between the substrate and the Mo elemental target is 28cm.

[0072] S4. Using a Cr elemental target as the magnetron sputtering target, a Cr layer was deposited on the second Mo layer using synchronous pulsed bias HIPIMS magnetron sputtering technology. Specifically, the substrate was preheated to 300℃, the Ar gas flow rate was 80 sccm, the substrate bias voltage was -180V, the pulse frequency was 700Hz, the pulse width was 167μs, the power of the cathode magnetron target was 5000W, the discharge voltage was 800V, the peak current was 8A, the synchronous bias mode of the HiPIMS power supply was used, the bias power supply and the HiPIMS sputtering cathode power supply were controlled by the signal generator, the deposition time was 13h, and the target spacing between the substrate and the Cr elemental target was 28cm, finally obtaining a zirconium alloy cladding composite protective coating.

[0073] Example 5

[0074] This embodiment provides a zirconium alloy cladding composite protective coating, comprising a first Mo layer, a second Mo layer, and a Cr layer arranged sequentially from bottom to top, and is prepared by the following method:

[0075] S1. The substrate undergoes mechanical polishing, ultrasonic cleaning, and argon ion etching. The argon ion etching process specifically includes the following steps: preheating the substrate to 400°C, heating the cavity to 200°C, and evacuating the vacuum pressure inside the cavity to 3.0 × 10⁻⁶. -5 After Torr, argon gas with a flow rate of 100 sccm is introduced into the cavity, the linear anodic ion source current is set to A, the bias voltage is -500V, and the substrate is argon ion etched for 100 min.

[0076] S2. The substrate pretreated in step S1 is placed in a vacuum chamber. Using a Mo elemental target as the magnetron sputtering target, the first Mo layer is deposited using synchronous pulsed bias HIPIMS magnetron sputtering technology. Specifically, the substrate is preheated to 400°C, the Ar gas flow rate is 100 sccm, the substrate bias voltage is -200V, the pulse frequency is 1000Hz, the pulse width is 200μs, the cathode magnetron target power is 2500W, the discharge voltage is 800V, the peak current is 10A, the synchronous bias mode of the HiPIMS power supply is used, the bias power supply and the HiPIMS sputtering cathode power supply are controlled by the signal generator, the deposition time is 100min, and the target spacing between the substrate and the Mo elemental target is 30cm.

[0077] S3. Using a Mo elemental target as the magnetron sputtering target, a second Mo layer is deposited on the first Mo layer using DC magnetron sputtering technology. Specifically, the substrate is preheated to 400℃, the Ar gas flow rate is 100 sccm, the substrate bias voltage is -200V, the cathode magnetron target power is 3000W, the discharge voltage is 600V, the peak current is 10A, the deposition time is 7h, and the target spacing between the substrate and the Mo elemental target is 30cm.

[0078] S4. Using a Cr elemental target as the magnetron sputtering target, a Cr layer was deposited on the second Mo layer using synchronous pulsed bias HIPIMS magnetron sputtering technology. Specifically, the substrate was preheated to 400℃, the Ar gas flow rate was 100 sccm, the substrate bias voltage was -200V, the pulse frequency was 1000Hz, the pulse width was 200μs, the power of the cathode magnetron target was 6000W, the discharge voltage was 1000V, the peak current was 10A, the synchronous bias mode of the HiPIMS power supply was used, the bias power supply and the HiPIMS sputtering cathode power supply were controlled by the signal generator, the deposition time was 15h, and the target spacing between the substrate and the Cr elemental target was 30cm. Finally, a zirconium alloy cladding composite protective coating was obtained.

[0079] Comparative Example 1

[0080] This comparative example provides a composite coating, which differs from Example 1 only in that the composite coating of this comparative example does not contain a first Mo layer, that is, step S2 is not performed. Everything else is the same as Example 1, and will not be repeated here.

[0081] Comparative Example 2

[0082] This comparative example provides a coating that differs from Example 1 only in that it only has a Cr coating, i.e. steps S2 and S3 are not performed. Everything else is the same as in Example 1, and will not be repeated here.

[0083] 1. Physical performance testing:

[0084] The inventors conducted performance tests on the zirconium alloy cladding composite protective coating prepared in Example 1, the composite coating prepared in Comparative Example 1, and the coating prepared in Comparative Example 2. The test results are as follows: Figures 2-6 As shown, where Figure 2 This is a transmission electron microscope (TEM) image of the zirconium alloy cladding composite protective coating prepared in Example 1. Figure 3 This is a single-crystal diffraction pattern of the Mo layer (columnar crystal) of the zirconium alloy cladding composite protective coating prepared in Example 1. Figure 4 This is a selected area electron diffraction pattern of the Mo layer (nanocrystalline) of the zirconium alloy cladding composite protective coating prepared in Example 1. Figure 5 The images show cross-sectional electron backscattering diffraction patterns of the zirconium alloy cladding composite protective coating prepared in Example 1 and the composite coating prepared in Comparative Example 1. Figure 6The images show the XRD patterns of the zirconium alloy cladding composite protective coating prepared in Example 1 and the composite coating prepared in Comparative Example 1.

[0085] from Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 The relevant test results show that the total thickness of the zirconium alloy cladding composite protective coating prepared in Example 1 is 10.6 μm, with a thickness ratio of approximately Cr:Mo layer (columnar crystal):Mo layer (nanocrystalline) = 12:3:1. The Cr layer has a body-centered cubic structure with a (200) preferred orientation and a texture coefficient TC of 0.99. The Mo layer (columnar crystal) has a body-centered cubic structure, and the Mo layer (nanocrystalline) has a face-centered cubic structure.

[0086] The total thickness of the composite coating prepared in Comparative Example 1 was 11.4 μm. The Cr layer had a body-centered cubic structure with a (200) preferred orientation and a texture coefficient TC of 0.99. The Mo layer also had a body-centered cubic structure.

[0087] 2. Water vapor corrosion test

[0088] Zirlo zirconium alloy substrate, zirconium alloy workpiece with the zirconium alloy cladding composite protective coating prepared in Example 1 (sample 1), zirconium alloy workpiece with the composite coating prepared in Comparative Example 1 (sample 2), and zirconium alloy workpiece with the coating prepared in Comparative Example 2 (sample 3) were oxidized in a water vapor environment at 1200℃ for 0.5 h with a water vapor flow rate of 1.5 g / min. To ensure the accuracy of the oxidation weight gain data, at least three samples were tested for each oxidation parameter, and the average oxidation weight gain was taken. Specific test data are shown in Table 1.

[0089] Table 1. Experimental data on water vapor corrosion

[0090]

[0091] The data in the table above show that the zirconium alloy cladding composite protective coating prepared on the zirconium alloy surface by this invention exhibits significantly lower oxidation weight gain compared to the zirconium alloy substrate, the single-layer Mo+Cr coating sample, and the single-layer Cr coating sample. Furthermore, after high-temperature steam oxidation, no Zr / Cr interdiffusion layer appeared inside the composite protective coating sample and the single-layer Mo+Cr coating sample, indicating that the zirconium alloy cladding composite protective coating inhibits Zr / Cr interdiffusion and significantly enhances the accident tolerance of the zirconium alloy workpiece.

[0092] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A zirconium alloy cladding composite protective coating, characterized in that, The zirconium alloy cladding composite protective coating comprises a first Mo layer, a second Mo layer, and a Cr layer arranged sequentially from bottom to top. The thickness ratio of the Cr layer to the second Mo layer is (3-7):1, and the thickness ratio of the first Mo layer to the second Mo layer is (2-5):

1. The first Mo layer has a nanocrystalline morphology, and the second Mo layer has a columnar crystalline morphology. The coating is prepared by the following method: S1. Pretreatment of the substrate; S2. The substrate pretreated in step S1 is placed in a vacuum chamber, and the first Mo layer is deposited using a Mo elemental target as a magnetron sputtering target and synchronous pulse bias HIPIMS magnetron sputtering technology. S3. Using a Mo elemental target as a magnetron sputtering target, a second Mo layer is deposited on the first Mo layer using DC magnetron sputtering technology. S4. Using a Cr elemental target as the magnetron sputtering target, a Cr layer is deposited on the second Mo layer using synchronous pulsed bias HIPIMS magnetron sputtering technology, and finally a zirconium alloy cladding composite protective coating is obtained.

2. The zirconium alloy cladding composite protective coating as described in claim 1, characterized in that, The Cr layer has a body-centered cubic structure with a (200) preferred orientation, a texture coefficient TC of 0.7-1.0, a grain size of 300-900 nm, and a thickness of 5-20 μm.

3. The zirconium alloy cladding composite protective coating as described in claim 1, characterized in that, The second Mo layer has a body-centered cubic structure and a thickness of 1-10 μm.

4. The zirconium alloy cladding composite protective coating as described in claim 1, characterized in that, The first Mo layer has a face-centered cubic structure and a thickness of 0.1-2 μm.

5. The zirconium alloy cladding composite protective coating as described in claim 1, characterized in that, The thickness of the zirconium alloy cladding composite protective coating is 5-30 μm.

6. The zirconium alloy cladding composite protective coating as described in claim 1, characterized in that, In step S1, the pretreatment includes mechanical polishing, ultrasonic cleaning, and argon ion etching. The argon ion etching specifically includes the following steps: preheating the substrate to 100~400℃, heating the cavity temperature to 200℃, and evacuating the vacuum pressure inside the cavity to 1.0×10⁻⁶. -5 ~3.0×10 -5 After Torr, argon gas with a flow rate of 10~100 sccm is introduced into the cavity, the linear anodic ion source current is set to 0.1~1A, the bias voltage is -100~-500V, and the substrate is argon ion etched for 10~100min.

7. The zirconium alloy cladding composite protective coating as described in claim 1, characterized in that, In step S2, the deposition parameters of the first Mo layer are as follows: the substrate is preheated to 100~400℃, the Ar gas flow rate is 20-100sccm, the substrate bias voltage is -10~-200V, the pulse frequency is 100~1000Hz, the pulse width is 20-200μs, the cathode magnetron target power is 100~2500W, the discharge voltage is 100~800V, the peak current is 1~10A, the synchronous bias mode of the HiPIMS power supply is adopted, the bias power supply and the HiPIMS sputtering cathode power supply are controlled by the signal generator, the deposition time is 10~100min, and the target spacing between the substrate and the Mo elemental target is 5~30cm.

8. The zirconium alloy cladding composite protective coating as described in claim 1, characterized in that, In step S3, the deposition parameters of the second Mo layer are as follows: the substrate is preheated to 100~400℃, the Ar gas flow rate is 20~100sccm, the substrate bias voltage is -10~-200V, the cathode magnetron target power is 500~3000W, the discharge voltage is 200~600V, the peak current is 1~10A, the deposition time is 1~7h, and the target spacing between the substrate and the Mo elemental target is 5~30cm.

9. The zirconium alloy cladding composite protective coating as described in claim 1, characterized in that, In step S4, the deposition parameters of the Cr layer are as follows: the substrate is preheated to 100~400℃, the Ar gas flow rate is 20~100sccm, the substrate bias voltage is -10~-200V, the pulse frequency is 100~1000Hz, the pulse width is 20~200μs, the power of the cathode magnetron target is 1000~6000W, the discharge voltage is 500~1000V, the peak current is 1~10A, the synchronous bias mode of the HiPIMS power supply is adopted, the bias power supply and the HiPIMS sputtering cathode power supply are controlled by the signal generator, the deposition time is 5~15h, and the target spacing between the substrate and the Cr elemental target is 5~30cm.

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