Corrosion-resistant functional coating applicable to water-cooled fusion reactor and preparation method of corrosion-resistant functional coating

Abstract

The invention discloses a corrosion-resistant functional coating suitable for a water-cooled fusion reactor and a preparation method of the corrosion-resistant functional coating. The corrosion-resistant functional coating comprises a base layer Cr, a middle layer CrAl and an external shielding layer CrAlN from the surface of a substrate to the outside. The Cr / CrAl / CrAlN corrosion-resistant functional coating is deposited on the surface of the fusion reactor structure material by adopting a multi-arc ion plating method, and the obtained coating is good in compactness, high in adhesive strength and good in durability and has excellent corrosion resistance and oxidation resistance.

Description

Technical Field

[0001] The present application relates to the technical field of reactor materials, and in particular to a corrosion-resistant functional coating suitable for a water-cooled fusion reactor and a preparation method thereof. Background Art

[0002] With the continuous breakthroughs in a series of key technologies in the field of fusion, fusion energy has faced a critical critical point in the transition from laboratory to engineering and commercial application. During the licensing, construction, operation, maintenance and decommissioning of fusion reactors, the radioactive substances they emit have a significant impact on individual and collective doses, radiation protection and safety analysis. Therefore, evaluating radioactive substances and reducing radiation doses are key factors in ensuring the safety of workers and the public, reactors and the natural environment.

[0003] At present, the sources of radioactivity in water-cooled fusion reactors can be divided into two categories: (1) Activated corrosion products of structural materials: The structural materials of fusion reactors include stainless steel, low-activation steel, carbon steel, nickel-iron alloy, copper and some special components, etc. The elements involved are mainly Ni, Fe, Co, Mn, Cr, and Cu. These materials will corrode when in contact with coolant and will also be activated under neutron irradiation. After entering the coolant, they will migrate in the coolant loop and deposit in various parts of the cooling pipe. Subsequently, they will be adsorbed and eluted by ion exchange resins, and the workers responsible for handling these ion exchange resins will receive a large amount of radiation dose; in addition, the workers responsible for nuclear power plant maintenance will also receive radiation doses due to the radioactivity of the primary loop during the shutdown period. (2) Activated products of coolant: The coolant water of the fusion reactor will undergo an activation reaction under neutron irradiation. In addition, it also contains some impurity elements, such as Na, Fe, Cl, Li, etc., which will also be activated and turned into radioactive nuclides under neutron irradiation. Since the related nuclides of the coolant's own activation products are mainly N-16 and N-17, which have a short lifespan, the activated corrosion products of structural materials in fusion reactors are the main source of harm to nuclear power plants, the surrounding environment, and the safety of workers and the public.

[0004] Studies have shown that surface coating technology is a feasible technology that can effectively inhibit the corrosion of structural materials and thereby reduce activated corrosion products. Therefore, this application has developed a corrosion-resistant functional coating suitable for water-cooled fusion reactors and a preparation method thereof. The coating includes a base layer of Cr, an intermediate layer of CrAl and an external shielding layer of CrAlN, which has excellent corrosion resistance and antioxidant properties and excellent mechanical properties under high temperature, high pressure and oxygen-rich environments. Summary of the invention

[0005] In view of the above problems, the purpose of the present application is to provide a corrosion-resistant functional coating suitable for water-cooled fusion reactors and a preparation method thereof. The coating consists of three parts: a base layer Cr, an intermediate layer CrAl and an external shielding layer CrAlN. It can not only be tightly bonded to the substrate, but also has excellent corrosion resistance, thereby reducing the hazards of activated corrosion products produced by water-cooled fusion reactors.

[0006] This application is implemented through the following technical solutions:

[0007] One of the technical solutions of the present application is to provide a corrosion-resistant functional coating suitable for a water-cooled fusion reactor, the coating comprising a Cr base layer, a CrAl intermediate layer and a CrAlN external shielding layer sequentially deposited on the surface of a substrate.

[0008] Furthermore, the total thickness of the corrosion-resistant functional coating is 0.5 μm to 50 μm.

[0009] Furthermore, the thicknesses of the Cr base layer, the CrAl intermediate layer and the CrAlN external shielding layer are in the range of 0.1 μm to 20 μm respectively.

[0010] Furthermore, in the CrAl intermediate layer, the atomic content of the Cr element is 60 at.% to 95 at.%, and the atomic content of the Al element is 5 at.% to 40 at.%.

[0011] Preferably, the composition of the CrAl intermediate layer is: the atomic content of the Cr element is 93.4 at.% and the atomic content of the Al element is 6.6 at.%.

[0012] Furthermore, the matrix material is stainless steel, low-activation steel, carbon steel, nickel-iron alloy or copper.

[0013] One of the technical solutions of the present application is to provide a method for preparing a corrosion-resistant functional coating suitable for a water-cooled fusion reactor, wherein a Cr base layer, a CrAl intermediate layer and a CrAlN external shielding layer are sequentially deposited on a substrate material by a multi-arc ion plating method, and the method comprises the following steps:

[0014] Step 1, substrate treatment: grind and polish the substrate surface with sandpaper, degrease in 70-90% acetone, ultrasonically clean in 90-95% ethanol for 10-20 minutes, and then dry with compressed air.

[0015] Step 2, deposition of Cr as a base layer: using Cr as a target, a Cr base layer is deposited on the surface of the substrate, argon gas is introduced, the argon flow rate is 100-110 mL / min, the arc current of the Cr target is adjusted to 60A-150A, the bias voltage is -100V--200V, the duty cycle is 40%-60%, and the deposition time is 10-400min.

[0016] Step 3, deposition of the intermediate layer CrAl: using CrAl alloy as the target, introducing argon gas, the argon flow rate is 100-110 mL / min, adjusting the arc current of the CrAl target to 60A-150A, the bias voltage to -70V--200V, the duty cycle to 40%-60%, and the deposition time to 10-400 min.

[0017] Step 4, deposition of the external shielding layer CrAlN: CrAl alloy is used as the target material, argon and nitrogen are introduced, the argon flow rate is 100~110mL / min, the nitrogen flow rate is 160~200sccm, the arc current of the CrAl target is adjusted to 60A~150A, the bias voltage is -100V~-300V, the duty cycle is 40%~60%, and the deposition time is 10~400min. Post-coating heat treatment: After the external shielding layer CrAlN is deposited, the substrate containing the coating material is subjected to vacuum heat treatment.

[0018] This application has the following advantages and beneficial effects:

[0019] (1) The Cr / CrAl / CrAlN corrosion-resistant functional coating described in the present application has excellent corrosion resistance and oxidation resistance under high temperature, high pressure and oxygen-rich environment. In a high temperature environment, a mixed oxide of Cr2O3 and Al2O3 is produced, and its structure is more compact, so that the oxidation resistance is significantly improved.

[0020] (2) The present application adopts multi-arc ion plating technology to prepare Cr / CrAl / CrAlN corrosion-resistant functional coatings. By adjusting the arc current, bias voltage and deposition time, a surface coating with good density, strong adhesion, high strength and durability can be obtained, which significantly improves the deposition efficiency.

[0021] (3) The preparation process of the Cr / CrAl / CrAlN corrosion-resistant functional coating described in this application is simple, the coating thickness is reasonably designed, and because the hardness of the coatings is not the same, there is an alternation between soft and hard. Therefore, relative sliding can occur under certain conditions, reducing internal stress and significantly improving the overall toughness of the coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The schematic diagram of the structure of a corrosion-resistant functional coating suitable for a water-cooled fusion reactor according to the present invention. DETAILED DESCRIPTION

[0023] The present application is further described in detail below in conjunction with a specific embodiment. This embodiment is implemented based on the technical solution of the present application and is only used to explain the present application, and is not intended to limit the present application.

[0024] Example

[0025] like Figure 1 As shown, a corrosion-resistant functional coating suitable for a water-cooled fusion reactor, wherein the corrosion-resistant coating is composed of a Cr base layer, a CrAl intermediate layer, and a CrAlN external shielding layer from the substrate surface outward. The thickness of the corrosion-resistant coating is 5 μm, the thickness of the Cr base layer is 1 μm, the thickness of the CrAl intermediate layer is 2 μm, and the thickness of the CrAlN external shielding layer is 2 μm.

[0026] In this embodiment, the composition of the CrAl intermediate layer is: the atomic content of the Cr element is 93.4 at. %, and the atomic content of the Al element is 6.6 at. %.

[0027] The preparation method of the above Cr / CrAl / CrAlN corrosion resistant functional coating is to deposit a Cr base layer, a CrAl intermediate layer and a CrAlN external shielding layer on the substrate surface in sequence by multi-arc ion plating. The specific steps are as follows:

[0028] Step 1: Use 316 stainless steel as the base material, grind and polish the base surface with 300-1200 mesh sandpaper, ultrasonically clean it with 80% acetone for 10 minutes, ultrasonically clean it in 95% ethanol for 20 minutes, and then dry it with compressed air.

[0029] Step 2: Load the dried 316 stainless steel into the furnace chamber and evacuate to 4.0×10 -3 Pa, start heating to 300℃, then fill in an appropriate amount of argon to make the gas pressure reach 1.5Pa, adjust the duty cycle to 50%, apply high bias voltage of -650V to -900V for a total of 15min, and perform plasma bias sputtering cleaning on the substrate surface.

[0030] Step 3: Maintain the vacuum degree at 4.0×10 -3 Pa conditions, the arc current is turned on to clean the target surface; the arc current is 120 A, the bias voltage is -600 V, the duty cycle is 50%, and the gas pressure is 0.5Pa.

[0031] Step 4: Adjust the arc current of the Cr target to 80 A, the bias voltage to -150 V, the duty cycle to 50%, and the deposition time to 40 min.

[0032] Step 5: Adjust the arc current of the CrAl target to 120 A, the bias voltage to -120 V, the duty cycle to 50%, and the deposition time to 1.5 h.

[0033] Step 6: Adjust the arc current of the CrAl target to 120 A, the bias voltage to -150 V, the nitrogen flow rate to 800 mL / min, and the deposition time to 1.5 h.

[0034] Step 7: Turn off the coating system, keep warm for 1 hour, and perform post-coating heat treatment.

[0035] Step 8, turn off the heating system. When the temperature drops below 75°C, turn off the vacuum system, fill with high-purity argon gas to normal pressure, and then you can take it out of the furnace.

[0036] Comparative Example 1

[0037] In this comparative example, 316 stainless steel was selected as the base material, and the base surface was ground and polished with 300-1200 mesh sandpaper, ultrasonically cleaned with 80% acetone for 10 minutes, ultrasonically cleaned in 95% ethanol for 20 minutes, and then dried with compressed air. The dried 316 stainless steel was placed in the furnace chamber and vacuumed to 4.0×10 - 3 After the temperature reaches 300°C, the substrate is heated to 300°C, and then a proper amount of argon is charged to make the pressure reach 1.5Pa. The duty cycle is adjusted to 50%, and a high bias voltage of -650V to -900V is applied for a total of 15 minutes. The substrate surface is cleaned by plasma bias sputtering to obtain the final product. That is, this comparative example only performs surface pretreatment on 316 stainless steel without depositing a coating.

[0038] Comparative Example 2

[0039] This comparative example provides a Cr coating, which is basically the same as the embodiment, except that only a 1 μm Cr primer layer is deposited.

[0040] The final products prepared in Example and Comparative Examples 1-2 were subjected to corrosion tests in 400°C / 20MPa high-pressure water. The results are shown in Table 1. The Cr / CrAl / CrAlN coating has better corrosion resistance.

[0041] The final products prepared in Example and Comparative Examples 1-2 were subjected to a constant temperature oxidation test at 1200° C. The results are shown in Table 1. The Cr / CrAl / CrAlN coating has better anti-oxidation performance.

[0042] Table 1 Experimental results of the final products prepared in Examples and Comparative Examples 1-2

[0043]

[0044] The above content is only for illustrating the technical solution of the present application. Without departing from the principle and technology of the present application, any changes made on the basis of the technical solution shall fall within the protection scope of the claims of the present invention.

Claims

1. A corrosion-resistant functional coating suitable for a water-cooled fusion reactor, characterized in that: The corrosion-resistant functional coating comprises a Cr base layer, a CrAl middle layer and a CrAlN external shielding layer which are sequentially deposited on the surface of the substrate.

2. The corrosion-resistant functional coating suitable for a water-cooled fusion reactor according to claim 1, characterized in that: The total thickness of the corrosion-resistant functional coating is 0.5 μm to 50 μm.

3. The corrosion-resistant functional coating suitable for a water-cooled fusion reactor according to claim 1, characterized in that: The thickness of the Cr base layer, the CrAl intermediate layer and the CrAlN outer shielding layer ranges from 0.1 μm to 20 μm respectively.

4. The corrosion-resistant functional coating suitable for a water-cooled fusion reactor according to claim 1, characterized in that: In the CrAl intermediate layer, the atomic content of the Cr element is 60at.%~95at.%, and the atomic content of the Al element is 5at.%~40at.%.

5. The corrosion-resistant functional coating suitable for a water-cooled fusion reactor according to claim 4, characterized in that: In the CrAl intermediate layer, the atomic content of the Cr element is 93.4 at. % and the atomic content of the Al element is 6.6 at. %.

6. The corrosion-resistant functional coating suitable for a water-cooled fusion reactor according to claim 1, characterized in that: The matrix material is stainless steel, low-activation steel, carbon steel, nickel-iron alloy or copper.

7. A method for preparing a corrosion-resistant functional coating suitable for a water-cooled fusion reactor, characterized in that: The steps include: Step 1, substrate treatment: finely grind and polish the substrate surface with sandpaper, degrease in 70-90% acetone, then ultrasonically clean in 90-95% ethanol for 10-20 minutes, and then dry with compressed air; Step 2, deposition of Cr as a base layer: using Cr as a target material, a Cr base layer is deposited on the surface of the substrate, argon gas is introduced, the argon gas flow rate is 100-110 mL / min, the arc current of the Cr target is adjusted to 60A-150A, the bias voltage is -100V--200V, the duty cycle is 40%-60%, and the deposition time is 10-400min; Step 3, deposition of the intermediate layer CrAl: using CrAl alloy as the target material, introducing argon gas, the argon gas flow rate is 100-110 mL / min, adjusting the arc current of the CrAl target to 60A-150A, the bias voltage to -70V--200V, the duty cycle to 40%-60%, and the deposition time to 10-400min; Step 4, deposition of the external shielding layer CrAlN: using CrAl alloy as the target material, introducing argon and nitrogen, the argon flow rate is 100-110 mL / min, the nitrogen flow rate is 160-200 sccm, the arc current of the CrAl target is adjusted to 60A-150A, the bias voltage is -100V--500V, the duty cycle is 40%-60%, and the deposition time is 10-400min.

8. The method for preparing a corrosion-resistant functional coating suitable for a water-cooled fusion reactor according to claim 7, characterized in that: In step 4, after the external shielding layer CrAlN is deposited, a post-plating heat treatment is performed.

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