A ta w v cr / al nanolayered coating and method of making
By alternating deposition of TaWVCr and Al nano-multilayer coatings, the problem of poor plasticity of TaWVCr coating in lead-bismuth fast reactors was solved, and the high plasticity and oxidation resistance of the coating were improved, thus enhancing the corrosion resistance of the cladding.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- XI AN JIAOTONG UNIV
- Filing Date
- 2024-04-11
- Publication Date
- 2026-07-31
AI Technical Summary
The TaWVCr coating has poor plasticity in lead-bismuth fast reactors and is prone to cracking and peeling during service, affecting the corrosion resistance of the cladding.
A nano-multilayer coating is formed by alternating deposition of TaWVCr and Al targets using magnetron sputtering. The alternating layers of TaWVCr and Al interrupt the continuous growth of columnar crystals, forming a soft-brittle-soft cyclic alternating structure, which improves the plasticity and oxidation resistance of the coating.
By adjusting the composition and structure of the coating, the plasticity and oxidation resistance of the coating were significantly improved, the corrosion resistance of the cladding was enhanced, and the density was reduced to meet service requirements.
Smart Images
Figure CN118291939B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of material surface modification, specifically to a TaWVCr / Al nano-multilayer coating and its preparation method. Background Technology
[0002] Lead-bismuth fast reactors are among the most promising fourth-generation nuclear reactors, but the corrosion and oxidation of their fuel cladding materials in the high-temperature liquid lead-bismuth environment seriously threatens the safe operation of the reactor. Currently, surface coating technology is the most direct and effective way to improve the corrosion resistance of the cladding. Refractory high-entropy alloys have attracted much attention in recent years due to their excellent high-temperature mechanical properties, structural stability, and corrosion resistance, making them ideal candidate materials for lead-bismuth fast reactor cladding coatings. Ta, W, V, and Cr elements have advantages such as high melting points, good high-temperature strength and oxidation resistance, low lead-bismuth solubility, and low thermal neutron capture cross-section, which can provide good protection for lead-bismuth fast reactor cladding materials. However, they also have certain drawbacks: lead-bismuth fast reactor cladding materials will deform due to irradiation swelling during service, so the coating needs to have good plasticity. However, TaWVCr coatings have poor plasticity and may crack or peel off during service.
[0003] Based on the above problems, it is necessary to improve the TaWVCr coating to enhance its corrosion resistance and anti-corrosion performance. Summary of the Invention
[0004] To address the problems existing in the prior art, this invention provides a TaWVCr / Al nano-multilayer coating and its preparation method. By using two targets, TaWVCr and Al, and depositing them alternately by magnetron sputtering, the two coatings are combined to form a heterogeneous interface. This disrupts the continuous growth of columnar crystals throughout the thickness of the coating, thereby improving the plasticity and oxidation resistance of the coating and enhancing the corrosion resistance of the cladding.
[0005] This invention is achieved through the following technical solution:
[0006] A TaWVCr / Al nanolayered coating comprises alternating layers of TaWVCr and Al, wherein the grain morphology of the TaWVCr and Al layers is columnar crystal, and the columnar crystal size is nanocrystal.
[0007] Preferably, the thickness of the single-layer TaWVCr layer is 2-100 nm, and the thickness of the single-layer Al layer is 2-100 nm.
[0008] Preferably, the hardness of the TaWVCr / Al nano-multilayer coating is 10.5 GPa-7.2 GPa.
[0009] A method for preparing a TaWVCr / Al nanolayered coating includes the following steps:
[0010] In a vacuum environment, TaWVCr and Al targets were alternately used to perform magnetron sputtering on the substrate. After sputtering to a preset thickness, the substrate was cooled to room temperature in the furnace to obtain a TaWVCr / Al nano multilayer coating.
[0011] The number of modulation cycles for the coating obtained by magnetron sputtering is 2-20, and the deposition thickness of the TaWVCr alloy target and Al target is 2-100 nm in each modulation cycle.
[0012] Preferably, the TaWVCr target is sputtered using a DC power supply, and the Al target is sputtered using an AC power supply. The power of the TaWVCr target and the Al target is 150-200W. During the deposition process, the argon gas flow rate is 60sccm, the deposition pressure is 0.5Pa, and the substrate rotation speed is 15r / min.
[0013] Preferably, the TaWVCr consists of two DC targets and the Al target consists of one AC target.
[0014] Preferably, the sputtering time of the TaWVCr target and the Al target in each modulation cycle is 50 to 2500 s.
[0015] Preferably, the substrate is ultrasonically cleaned and dried before magnetron sputtering, and a TaWVCr / Al nano-multilayer coating is sputtered and deposited on the dried substrate.
[0016] Preferably, the dried substrate is vacuum etched, and then the etched substrate is pre-sputtered to remove the adsorbed material on the surface of the target material.
[0017] Preferably, the etching and pre-sputtering methods are as follows:
[0018] Ar+ ions are used to etch the substrate surface, followed by pre-sputtering. Argon gas is introduced for at least 30 seconds before pre-sputtering, and the pre-sputtering time is at least 10 seconds to remove adsorbed substances on the target surface.
[0019] Compared with the prior art, the present invention has the following beneficial technical effects:
[0020] This invention provides a TaWVCr / Al nanolayered coating. The mechanical behavior of this multilayered coating exhibits strong size dependence. By adding a softer Al layer to a relatively brittle high-entropy TaWVCr monolayer coating, a soft-brittle-soft cyclic alternating structure is formed. When subjected to stress and deformation occurs, cracks initiate in the brittle TaWVCr phase. Further propagation is inhibited by the surrounding, more ductile Al layer. Whether the crack can continue to propagate depends on the stress intensity at the crack tip and the inhibitory effect of the Al layer's plastic deformation on crack propagation. Adding the Al layer improves the coating's brittleness. The stress intensity at the crack tip increases with increasing TaWVCr layer thickness, while the plastic deformation capacity of the Al layer increases with increasing Al layer thickness; these two mechanisms are in competition. Size dependence allows for precise control of the multilayered coating's strength and toughness, resulting in a nanolayered coating that meets service performance requirements.
[0021] Furthermore, Ta, W, V, and Cr elements possess advantages such as high melting points, excellent high-temperature strength, low lead-bismuth solubility, and low thermal neutron capture cross-sections. They readily form a Cr₂O₃ protective film in liquid lead-bismuth, and these refractory alloying elements can protect the cladding material for normal operation in high-temperature irradiation environments. Adding an Al layer to the TaWVCr high-entropy coating disrupts columnar crystal growth during the deposition process, making it difficult for liquid lead-bismuth to corrode inwards through grain boundaries. Simultaneously, it facilitates the formation of multiple Al₂O₃ protective films in the high-temperature liquid lead-bismuth environment, further enhancing the coating's corrosion resistance.
[0022] By adjusting the alternating deposition time of the target materials during the preparation process of this invention, TaWVCr / Al nanolayer coatings with different modulation ratios can be prepared. The mechanical properties and corrosion resistance of the coatings can be controlled and improved, resulting in excellent corrosion resistance. Attached Figure Description
[0023] Figure 1 XRD pattern of TaWVCr / Al nanolayered coating prepared by magnetron sputtering in this invention;
[0024] Figure 2 This is a cross-sectional scanning electron microscope image of the TaWVCr / Al nanolayered coating of the present invention;
[0025] Figure 3 The images show the transmission electron microscope (a), STEM energy dispersive spectroscopy (bg), and selected electron diffraction (h) patterns of the TaWVCr / Al nanolayered coating sample with an Al layer thickness of 10 nm.
[0026] Figure 4 This is a graph showing the nanoindentation hardness of the TaWVCr / Al nano multilayer coatings with different Al layer thicknesses according to the present invention. Detailed Implementation
[0027] The present invention will now be described in further detail with reference to the accompanying drawings. These descriptions are intended to explain the invention and not to limit it.
[0028] A TaWVCr / Al nanolayered coating comprises alternating layers of TaWVCr and Al, wherein the grain morphology of the TaWVCr and Al layers is columnar, and the size of the columnar crystals is stable within the nanocrystalline range.
[0029] The thickness of the single-layer TaWVCr layer is 2-100 nm, the thickness of the single-layer Al layer is 2-100 nm, and its hardness is 10.5 GPa-7.2 GPa.
[0030] A method for preparing a TaWVCr / Al nanolayered coating includes the following steps:
[0031] Step 1: Perform ultrasonic cleaning and drying on the surface of the silicon substrate;
[0032] Specifically, the silicon substrate is polished on one side, then ultrasonically cleaned in acetone and ethanol for 15 minutes each, and then quickly dried to make the silicon substrate surface clean and free of stains and dust, with a roughness of less than 0.8 nm.
[0033] Step 2: In a high vacuum environment, Ar+ ions are used for etching to remove impurities from the substrate surface, and then the substrate is pre-sputtered.
[0034] The silicon substrate is fixed on the base plate and sent into the vacuum coating chamber. Then, the back vacuum is evacuated to 1.0 × 10⁻⁶. -4 The etching process is carried out at a pressure of 1.0 Pa and a time of 5 min, with an etching power of 200 W, an etching gas pressure of 1.0 Pa, and an etching time of 5 min.
[0035] The pre-sputtering time is 10s, and the silicon substrate rotation speed during deposition is 15r / min.
[0036] Step 3: Using a TaWVCr alloy target and an Al elemental target, TaWVCr and Al layers are alternately deposited by magnetron sputtering on the substrate obtained in Step 2 to obtain a metal TaWVCr / Al coating with a nano-level structure.
[0037] The TaWVCr alloy target was sputtered using a DC power supply, while the Al elemental target was sputtered using an AC power supply. The power for both the TaWVCr alloy target and the Al elemental target was 200W, the deposition gas pressure was 0.5 Pa, and the deposition temperature was room temperature. The purity of both the TaWVCr alloy target and the Al elemental target was not less than 99.95 wt.%.
[0038] The number of modulation cycles for the magnetron sputtering deposition is 2-20; in the same modulation cycle, the sputtering time of the TaWVCr alloy target is 50-2500s, the sputtering time of the Al elemental target is 50-2500s, the thickness of the TaWVCr layer is 2-100nm, and the thickness of the Al layer is 2-100nm.
[0039] Step 4: The metal TaWVCr / Al coating obtained in Step 3 is vacuum cooled to room temperature to obtain a TaWVCr / Al nano multilayer coating.
[0040] The coating was cooled to room temperature in a vacuum coating chamber to prevent peeling due to the difference in thermal expansion coefficients between the coating and the substrate. This resulted in a uniformly structured TaWVCr / Al nanolayered coating with strong interfacial adhesion.
[0041] The method for preparing the TaWVCr / Al nanolayered coating in this application involves first immersing a polished Si(111) substrate in acetone and anhydrous ethanol solutions for ultrasonic cleaning for 15 minutes to remove surface contaminants and dust, thereby improving the adhesion between the coating and the substrate. Next, a TaWVCr / Al nanolayered coating is prepared on the clean silicon substrate using magnetron sputtering deposition. The principle of this method is that after glow discharge, Ar gas generates a high density of Ar ions. These Ar+ ions are attracted to the negative electrode under the influence of an electric field and bombard the target material at a high rate, transferring some kinetic energy to the target atoms. Subsequently, the target atoms collide with other target atoms to form a cascade process. During this process, some target atoms gain sufficient kinetic energy to move outward, causing target atoms and secondary electrons to be sputtered out. Ultimately, TaWVCr and Al atoms move in opposite directions to deposit on the silicon substrate. Simultaneously, the secondary electrons circulate in a rotating manner under the influence of orthogonal electromagnetic fields, increasing the ionization rate, ion density, and energy of Ar, thus achieving high-rate sputtering. During implementation, the deposition power was set to 200W. By adjusting the same deposition gas pressure and different deposition times, the microstructure of the TaWVCr / Al nanolayered coating can be controlled, improving its plasticity while minimizing the reduction in TaWVCr hardness.
[0042] Example 1
[0043] A method for preparing a TaWVCr / Al nanolayered coating includes the following steps:
[0044] S1. The polished Si(111) substrate was ultrasonically cleaned in acetone and anhydrous ethanol for 15 min each, and then dried to remove impurities from the surface of the silicon substrate. The silicon substrate was then fixed on a substrate disk and automatically transported into the magnetron sputtering vacuum deposition chamber, where the back vacuum was evacuated to 1.0 × 10⁻⁶. -4Etching begins below Pa, with an etching power of 200W, an etching gas pressure of 1.0Pa, and a time of 5 minutes.
[0045] S2. Begin magnetron sputtering deposition of TaWVCr / Al nanolayers. First, argon gas is introduced for 30 seconds, followed by pre-sputtering for 10 seconds. Two metal TaWVCr DC targets and one metal Al AC target (purity 99.95 wt.%) are used for co-deposition. The deposition power is 200 W for both targets, the disk rotation speed is 15 r / min, the deposition pressure is set to 0.5 Pa, the argon flow rate is 60 sccm, and the deposition temperature is room temperature. The thickness of a single TaWVCr layer is set to 50 nm, the thickness of a single Al layer is set to 2 nm, the number of cycles is 20, and the total film thickness is 1.0 μm.
[0046] S3. After the sample has cooled naturally to room temperature in the vacuum coating chamber for 2-3 hours, it is removed to obtain a TaWVCr / Al nano-multilayer coating with a thickness of approximately 1.0 μm. The microstructure of the prepared TaWVCr / Al nano-multilayer coating is characterized. The grain morphology of the TaWVCr / Al nano-multilayer coating is columnar, the size of the columnar crystals is stable in the nanocrystal range, and the hardness is approximately 10.5 GPa.
[0047] Example 2
[0048] A method for preparing a TaWVCr / Al nanolayered coating includes the following steps:
[0049] S1. The polished Si(111) substrate was ultrasonically cleaned in acetone and anhydrous ethanol for 15 min each, and then dried to remove impurities from the surface of the silicon substrate. The silicon substrate was then fixed on a substrate disk and automatically transported into the magnetron sputtering vacuum deposition chamber, where the back vacuum was evacuated to 1.0 × 10⁻⁶. -4 Etching begins below Pa, with an etching power of 200W, an etching gas pressure of 1.0Pa, and a time of 5 minutes.
[0050] S2. Begin magnetron sputtering deposition of TaWVCr / Al nanolayers. First, argon gas is introduced for 30 seconds, followed by pre-sputtering for 10 seconds. Two metal TaWVCr DC targets and one metal Al AC target (purity 99.95 wt.%) are used for co-deposition. The deposition power is 200 W for both targets, the disk rotation speed is 15 r / min, the deposition pressure is set to 0.5 Pa, the argon flow rate is 60 sccm, and the deposition temperature is room temperature. The thickness of a single TaWVCr layer is set to 50 nm, the thickness of a single Al layer is set to 6 nm, the number of cycles is 20, and the total film thickness is 1.1 μm.
[0051] S3. After the sample has cooled naturally to room temperature in the vacuum coating chamber for 2-3 hours, it is removed to obtain a TaWVCr / Al nano-multilayer coating with a thickness of approximately 1.1 μm. The microstructure of the prepared TaWVCr / Al nano-multilayer coating is characterized. The grain morphology of the TaWVCr / Al nano-multilayer coating is columnar, the size of the columnar crystals is stable in the nanocrystal range, and the hardness is approximately 8.2 GPa.
[0052] Example 3
[0053] A method for preparing a TaWVCr / Al nanolayered coating includes the following steps:
[0054] S1. The polished Si(111) substrate was ultrasonically cleaned in acetone and anhydrous ethanol for 15 min each, and then dried to remove impurities from the surface of the silicon substrate. The silicon substrate was then fixed on a substrate disk and automatically transported into the magnetron sputtering vacuum deposition chamber, where the back vacuum was evacuated to 1.0 × 10⁻⁶. -4 Etching begins below Pa, with an etching power of 200W, an etching gas pressure of 1.0Pa, and a time of 5 minutes.
[0055] S2. Begin magnetron sputtering deposition of TaWVCr / Al nanolayers. First, argon gas is introduced for 30 seconds, followed by pre-sputtering for 10 seconds. Two metal TaWVCr DC targets and one metal Al AC target (purity 99.95 wt.%) are used for co-deposition. The deposition power is 200 W for both targets, the disk rotation speed is 15 r / min, the deposition pressure is set to 0.5 Pa, the argon flow rate is 60 sccm, and the deposition temperature is room temperature. The thickness of a single TaWVCr layer is set to 50 nm, the thickness of a single Al layer is set to 10 nm, the number of cycles is 20, and the total film thickness is 1.2 μm.
[0056] S3. After the sample has cooled naturally to room temperature in the vacuum coating chamber for 2-3 hours, it is removed to obtain a TaWVCr / Al nano-multilayer coating with a thickness of approximately 1.1 μm. The microstructure of the prepared TaWVCr / Al nano-multilayer coating is characterized. The grain morphology of the TaWVCr / Al nano-multilayer coating is columnar, and the size of the columnar crystals is stable in the nanocrystal range. The hardness is approximately 7.2 GPa.
[0057] Example 4
[0058] A method for preparing a TaWVCr / Al nanolayered coating includes the following steps:
[0059] S1. The polished Si(111) substrate was ultrasonically cleaned in acetone and anhydrous ethanol for 20 min each, and then dried to remove impurities from the surface of the silicon substrate. The silicon substrate was then fixed on a substrate disk and automatically transported into the magnetron sputtering vacuum deposition chamber, where the back vacuum was evacuated to 1.0 × 10⁻⁶.-4 Etching begins below Pa, with an etching power of 180W, an etching gas pressure of 1.2Pa, and a time of 8 minutes.
[0060] S2. Begin magnetron sputtering deposition of TaWVCr / Al nanolayers. First, argon gas is introduced for 45 seconds, followed by pre-sputtering for 15 seconds. A DC TaWVCr target and an AC Al target (purity 99.95 wt.%) are used for co-deposition. The deposition power for both targets is 150 W, the disk rotation speed is 15 r / min, the deposition pressure is set to 0.6 Pa, the argon flow rate is 90 sccm, the deposition temperature is room temperature, the thickness of a single TaWVCr layer is set to 2 nm, the thickness of a single Al layer is set to 100 nm, and the number of cycles is 2.
[0061] S3. After the sample has cooled naturally to room temperature in the vacuum coating chamber for 2-3 hours, it is removed to obtain a TaWVCr / Al nano-multilayer coating. The microstructure of the prepared TaWVCr / Al nano-multilayer coating is characterized. The grain morphology of the TaWVCr / Al nano-multilayer coating is columnar, and the size of the columnar crystals is stable in the nanocrystal range.
[0062] Example 5
[0063] A method for preparing a TaWVCr / Al nanolayered coating includes the following steps:
[0064] S1. The polished Si(111) substrate was ultrasonically cleaned in acetone and anhydrous ethanol for 15 min each, and then dried to remove impurities from the surface of the silicon substrate. The silicon substrate was then fixed on a substrate disk and automatically transported into the magnetron sputtering vacuum deposition chamber, where the back vacuum was evacuated to 1.0 × 10⁻⁶. -4 Etching begins below Pa, with an etching power of 160W, an etching gas pressure of 1.2Pa, and a time of 10min.
[0065] S2. Begin magnetron sputtering deposition of TaWVCr / Al nanolayers. First, argon gas is introduced for 40 seconds, followed by pre-sputtering for 12 seconds. A DC TaWVCr target and an AC Al target (purity 99.95 wt.%) are used for co-deposition. The deposition power for both is 160 W, the disk rotation speed is 15 r / min, the deposition pressure is set to 0.5 Pa, the argon flow rate is 75 sccm, the deposition temperature is room temperature, the thickness of a single TaWVCr layer is set to 100 nm, the thickness of a single Al layer is set to 2 nm, and the number of cycles is 10.
[0066] S3. After the sample has cooled naturally to room temperature in the vacuum coating chamber for 2-3 hours, it is removed to obtain a TaWVCr / Al nano-multilayer coating. The microstructure of the prepared TaWVCr / Al nano-multilayer coating is characterized. The grain morphology of the TaWVCr / Al nano-multilayer coating is columnar, and the size of the columnar crystals is stable in the nanocrystal range.
[0067] like Figures 1-4 As shown, the prepared TaWVCr / Al nanolayered coating has columnar crystal morphology with stable size within the nanocrystalline range. XRD results of nanolayered coatings with different Al layer thicknesses show that their structure is a BCC solid solution, with uniform and dense intralayer structure and excellent overall performance. The coating hardness gradually decreases with increasing Al layer thickness.
[0068] This application presents a TaWVCr / Al nanolayered coating. Ta, W, V, and Cr elements possess advantages such as high melting point, good high-temperature strength and oxidation resistance, low lead-bismuth solubility, and low thermal neutron capture cross-section. Al element exhibits good oxidation and corrosion resistance, plasticity, and low density. The two coatings are combined using alternating magnetron sputtering deposition of TaWVCr and Al targets to form a heterogeneous interface. This disrupts the continuous growth of columnar crystals throughout the coating thickness, thereby improving the coating's plasticity and oxidation resistance while reducing its density. By combining the advantages of both coatings, TaWVCr / Al nanolayered coatings with different modulation ratios are prepared. These TaWVCr / Al nanolayered coatings possess a uniform and dense microstructure and excellent performance.
[0069] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.
Claims
1. A TaWVCr / Al nano-multilayer coating, characterized in that, It includes alternating layers of TaWVCr and Al, wherein the grain morphology of the TaWVCr and Al layers is columnar crystal, and the size of the columnar crystal is nanocrystal.
2. The TaWVCr / Al nano-multilayer coating according to claim 1, characterized in that, The thickness of a single TaWVCr layer is 2-100 nm, and the thickness of a single Al layer is 2-100 nm.
3. The TaWVCr / Al nanolayered coating according to claim 1, characterized in that, The hardness of the TaWVCr / Al nano-multilayer coating is 10.5 GPa-7.2 GPa.
4. A method for preparing a TaWVCr / Al nanolayered coating, characterized in that, Includes the following steps: In a vacuum environment, TaWVCr and Al targets were alternately used to perform magnetron sputtering on the substrate. After sputtering to a preset thickness, the substrate was cooled to room temperature in the furnace to obtain a TaWVCr / Al nano multilayer coating. The number of modulation cycles for the coating obtained by magnetron sputtering is 2-20, and the deposition thickness of the TaWVCr alloy target and Al target is 2-100 nm in each modulation cycle.
5. The method for preparing a TaWVCr / Al nanolayered coating according to claim 4, characterized in that, The TaWVCr target is sputtered using a DC power supply, and the Al target is sputtered using an AC power supply. The power of the TaWVCr target and the Al target is 150-200W. During the deposition process, the argon gas flow rate is 60sccm, the deposition pressure is 0.5Pa, and the substrate rotation speed is 15r / min.
6. The method for preparing a TaWVCr / Al nanolayered coating according to claim 4, characterized in that, The TaWVCr consists of two DC targets, and the Al target consists of one AC target.
7. The method for preparing a TaWVCr / Al nanolayered coating according to claim 4, characterized in that, The sputtering time for TaWVCr and Al targets in each modulation cycle is 50–2500 s.
8. The method for preparing a TaWVCr / Al nanolayered coating according to claim 4, characterized in that, The substrate was ultrasonically cleaned and dried before magnetron sputtering, and a TaWVCr / Al nano-multilayer coating was sputtered onto the dried substrate.
9. The method for preparing a TaWVCr / Al nanolayered coating according to claim 8, characterized in that, The dried substrate is vacuum etched, and then the etched substrate is pre-sputtered to remove the adsorbed material on the surface of the target material.
10. The method for preparing a TaWVCr / Al nanolayered coating according to claim 9, characterized in that, The etching and pre-sputtering methods are as follows: Using Ar + The substrate surface is etched by ions, and then pre-sputtering is performed. The argon gas is introduced for at least 30 seconds before pre-sputtering, and the pre-sputtering time is at least 10 seconds to remove the adsorbed material on the target surface.