Composite coating resistant to high-temperature liquid lead / lead bismuth alloy corrosion and preparation method of composite coating

Abstract

The invention discloses a composite coating resistant to high-temperature liquid lead / lead bismuth alloy corrosion and a preparation method thereof, the composite coating is an AlTiYO / CrAl coating, CrAl serves as a coating transition layer, and the AlTiYO / CrAl coating is deposited on a structural steel substrate. The preparation method comprises the steps that a structural steel base material is pretreated; crAl is adopted as a coating transition layer, and a CrAl coating is obtained through a pure Cr target material and a CrAl target material; the method comprises the following steps: carrying out multi-arc ion plating on AlTiYO by adopting an AlTiY alloy target to obtain an AlTiYO / CrAl initial coating; and high-temperature annealing. The AlTiYO / CrAl coating obtained through the method has the good liquid lead / lead bismuth corrosion resistance at the high temperature. And a multi-arc ion plating method is adopted, so that the uniformity and higher bonding strength of the coating are ensured, the deposition temperature is lower, and the matrix performance is not influenced.

Description

Technical Field

[0001] The present invention relates to the technical field of surface corrosion protection of structural steel in a high-temperature liquid lead / lead-bismuth environment, and particularly relates to a composite coating resistant to corrosion by high-temperature liquid lead / lead-bismuth alloy and a preparation method thereof. Background Art

[0002] Nuclear energy is a base-load energy source that can maintain a stable power generation capacity in low-carbon energy for a long time, and is an extremely important part of the clean energy system.

[0003] As an important technical branch in the field of fast reactors, lead-cooled fast reactors (LFRs) have received continuous attention. Lead or lead-bismuth eutectic alloy is used as the coolant in LFRs, and a closed fuel cycle technology route is adopted. The liquid lead-bismuth alloy (Lead-Bismuth Eutectic, LBE) has the following advantages as a coolant: (1) a low neutron absorption cross section; (2) no irradiation damage problem; (3) LBE as a coolant has excellent thermal properties and can transfer heat out of the system in a timely manner. The low melting point and high boiling point enable the system to operate at lower temperatures and pressures, reducing safety hazards; (4) low chemical activity in air and water, which can reduce the probability of chemical fires and explosions caused by coolant leakage. These advantages make reactors with LBE as a spallation target and coolant have significant advantages in terms of safety, reliability, and economy.

[0004] Since the concepts of lead-cooled fast reactors and ADS systems were proposed, the nuclear industry has been trying to find suitable structural materials to meet the design and construction requirements of current research reactors and future commercial reactors. After years of material research and screening, austenitic stainless steel, ferritic / martensitic steel (F / M steel), FeCrAl alloy, etc. have been locked in. Although lead-bismuth eutectic alloy is an ideal coolant, when structural steel is in high-temperature LBE, phenomena such as dissolution, oxidation, erosion, and liquid metal embrittlement will occur when the structural steel contacts LBE, causing serious damage to the reactor structural steel, endangering the safety and service life of the reactor, which is a safety issue that cannot be ignored in lead-cooled fast reactors.

[0005] To solve this problem, there are currently three main solutions: (1) developing suitable structural steel to form a dense oxide film on its surface in LBE, such as FeCrAl, ODS-FeCrAl steel, etc. (2) depositing a coating on the steel substrate. (3) modification of structural materials. Comparatively speaking, the coating can avoid the direct contact between the structural material and LBE, solve the compatibility problem between the structural material and LBE, improve the use temperature and service life of the structural material in LBE, and the coating hardly affects the mechanical properties of the structural material itself, ensuring the normal and safe operation of the ADS system. Therefore, depositing an outer coating on the steel substrate is a very good method.

[0006] Considering the application background and functional requirements of the LBE corrosion-resistant coating comprehensively, the most important basic performance requirements of the coating are reflected in the following three aspects: (1) The surface is dense with few defects and has self-healing ability to ensure the reliability of long-term service; (2) It has good heat conduction ability and does not affect the heat cycle process of the reactor; (3) It has good bonding with the substrate and is not easy to fall off under high-density and cyclic thermal loads and long-term irradiation conditions. At present, the common coatings mainly include metal coatings such as FeAl, FeCrAl, FeCrAlY, FeCrSi, and CrAl, and ceramic coatings such as Al2O3, TiC, TiN, and AlTiN.

[0007] For ceramic coatings, they have good properties, such as excellent chemical stability, good corrosion resistance and wear resistance, high hardness and strength, and have the potential to be used in strong erosion, high temperature, strong corrosion, and high-irradiation environments. However, ceramic materials have the inherent weakness of brittleness and the problem of large differences in thermophysical properties from metal materials. Depositing a coating on the substrate will result in poor bonding strength, which restricts the application of ceramic coatings in improving the corrosion resistance of lead-bismuth fast reactor claddings.

[0008] Therefore, how to apply ceramic coatings with excellent properties to improve the corrosion resistance of lead-bismuth fast reactor claddings, especially for the surface corrosion protection of structural steel in high-temperature (above 550 °C) liquid lead / lead-bismuth environments, is of great significance.

[0009] In view of this, this patent application is proposed. Summary of the Invention

[0010] The technical problem to be solved by the present invention is: the problem of poor bonding strength existing in the existing ceramic materials when used as coatings for the surface corrosion protection of structural steel in high-temperature liquid lead / lead-bismuth environments.

[0011] The present invention is achieved through the following technical solutions:

[0012] The first object of the present invention is to provide a composite coating resistant to high-temperature liquid lead / lead-bismuth alloy corrosion. The composite coating is an AlTiYO / CrAl coating, with CrAl as the coating transition layer, and the AlTiYO / CrAl coating is deposited on a structural steel substrate.

[0013] In the present invention, by using AlTiYO ceramic materials, doping yttrium oxide in the ceramic materials can inhibit the transformation of the AlTiO crystal form, improve the thermodynamic stability of AlTiO ceramics, and improve the inherent weakness of brittleness of the ceramic materials. Using CrAl as the coating transition layer can alleviate the difference in thermal expansion coefficients between the AlTiYO ceramic coating and the metal substrate, and at the same time endow the coating with self-healing ability and good corrosion resistance to liquid lead / lead-bismuth at high temperatures.

[0014] In an alternative embodiment, the thickness of the composite coating is 6 microns. Even with a relatively thin composite coating, it still has the ability to resist lead-bismuth corrosion at high temperatures.

[0015] In an alternative embodiment, the content of Al in the CrAl transition layer is 5 - 8 wt%, to increase the adhesion of the coating.

[0016] In an alternative embodiment, the coefficient of thermal expansion of the CrAl transition layer is (8 - 11.7)×10 -6 / K.

[0017] For the AlTiYO / CrAl coating material system of the present invention that resists corrosion by high-temperature liquid lead / lead-bismuth alloy, the coefficient of thermal expansion of Al2O3 is 8.0×10 -6 / K, and the coefficient of thermal expansion of the FeCrAl alloy substrate is about 11.7×10 -6 / K. Therefore, when the coefficient of thermal expansion of the CrAl transition layer is between 8 - 11.7×10 -6 / K, it can play a good buffering role, solve the problem of the large difference in thermophysical properties between ceramic materials and metal materials, and at the same time avoid the problem of poor bonding strength caused by the inherent weakness of the brittleness of ceramic materials.

[0018] In an alternative embodiment, the structural steel is an FeCrAl alloy substrate or low-activation ferritic or martensitic steel.

[0019] The second object of the present invention is to provide a method for preparing a composite coating that resists corrosion by high-temperature liquid lead / lead-bismuth alloy as described in any one of the above, and the AlTiYO / CrAl coating is prepared by a multi-arc ion plating method.

[0020] In the process of preparing the coating in the present invention, the multi-arc ion plating method is adopted, which has the characteristics of fast deposition speed, high target ionization rate, good throwing power, etc., thereby ensuring the uniformity of the coating and high bonding strength, and the deposition temperature is relatively low, which will not affect the properties of the substrate.

[0021] In an alternative embodiment, it includes the following steps:

[0022] (1) Pretreat the substrate material of the structural steel.

[0023] (2) Use CrAl as the coating transition layer, and deposit the CrAl transition layer on the substrate simultaneously with a pure Cr target and a CrAl target in an argon atmosphere. After the coating thickness reaches the set thickness, stop coating to obtain the CrAl coating.

[0024] (3) After natural cooling, multi-arc ion plating of AlTiYO is carried out using an AlTiY alloy target. The coating deposition on the substrate surface is terminated after reaching the set thickness, and the coating is naturally cooled to room temperature to obtain the AlTiYO / CrAl initial coating;

[0025] (4) After the coating is completed, the AlTiYO / CrAl initial coating is placed in an annealing furnace, and the vacuum is pumped to 1×10 -4 Pa. Under an argon atmosphere, it is heated to 300 - 600 °C at a heating rate of 10 - 20 °C / min and held for 6 - 8 h to obtain the AlTiYO / CrAl composite coating.

[0026] Furthermore, after multi-arc ion plating in the present invention, the coated sample is annealed at a relatively low temperature of 300 - 600 °C for 6 - 8 hours. This heat treatment can slowly release the free volume (i.e., structural relaxation) of the amorphous AlTiYO / CrAl coating, making the atomic arrangement of the coating denser. At the same time, this heat treatment can directly cause element diffusion between the CrAl coating and the substrate, enhancing the bonding force between the coating and the substrate, and reducing the difference in thermal expansion coefficient between the CrAl coating and the substrate. In addition, heat treatment at an appropriate temperature and time can reduce the internal stress generated during the deposition of the coating. If the heat treatment time is too short or the heat treatment temperature is too low, the free volume cannot be fully released, while too long heat treatment time or too high temperature may cause changes in the microstructure of the coating and the structural material substrate. The heat treatment time is further preferably 6 - 8 h. Further, the heating rate for heating to the annealing temperature of 500 - 600 °C is preferably 10 - 20 °C / min.

[0027] In an optional embodiment, in the step (2), 3 pure Cr targets and 1 CrAl target are used, and the composition of the CrAl target is 30 - 50 wt% Al and 50 - 70 wt% Cr.

[0028] Furthermore, in order to obtain a composite coating with better comprehensive properties (bonding strength, corrosion resistance, heat treatment at a relatively low temperature without affecting the substrate structure), in the step (2) of the present invention, 3 pure Cr targets and 1 CrAl target are used as the metal targets, and the composition of the CrAl target is 30 - 50 wt% Al and 50 - 70 wt% Cr. The advantage of such a design is to accurately control the Al content in the CrAl transition layer to 5 - 8 wt%. At the same time, it helps to obtain a dense amorphous AlTiYO / CrAl coating at a low temperature. Due to the short-range disorder structure of the dense amorphous AlTiYO / CrAl coating lacking defects and grain boundaries, and the uniform element distribution, the coating has more excellent corrosion resistance; the working temperature is also lower than the final heat treatment temperature of the used structural steel (~700 °C), and it will not affect the microstructure and mechanical properties of the steel substrate.

[0029] In an alternative embodiment, in step (2), when depositing the CrAl transition layer, the argon flow rate is 80 - 150 sccm, the substrate negative bias voltage is 80 - 150 V, the target current is 80 - 120 A, and the deposition time is 2 - 10 h. The required thickness is obtained through condition design. In an alternative embodiment, in step (3), the composition of the AlTiY alloy target is 30 - 50 wt% Ti, 0.2 - 0.5 wt% Y, and the balance is Al. In the present invention, by designing the composition of the AlTiY alloy target to be 30 - 50 wt% Ti, 0.2 - 0.5 wt% Y and coordinating with the composition of the CrAl target material being 30 - 50 wt% Al, 50 - 70 wt% Cr, a composite coating with better comprehensive performance can be obtained.

[0030] In an alternative embodiment, in step (3), the conditions for multi-arc ion plating of AlTiYO are: the oxygen flow rate is 110 - 150 sccm, the substrate negative bias voltage is 80 - 120 V, the target current is 80 - 100 A, and the deposition time is 1 - 5 h.

[0031] In an alternative embodiment, the pretreatment in step (1) is: after grinding or sandblasting the surface of the structural steel, ultrasonic cleaning is carried out successively with anhydrous ethanol and acetone, and then taken out and dried for use.

[0032] In the present invention, the surface of the substrate material is pretreated to facilitate the good adhesion of the AlTiYO / CrAl coating. In the present invention, it is preferred to perform corundum sandblasting on the substrate surface, and the sandblasting treatment can improve the bonding force between the AlTiYO / CrAl coating and the structural material.

[0033] In an alternative embodiment, after the pretreatment of the substrate material, the following process is further included:

[0034] Place the pretreated substrate material in the vacuum chamber of the multi-arc ion plating equipment, evacuate to 5×10 -3 Pa, and etch the surface of the sample in an argon atmosphere, with the substrate negative bias voltage being 150 V; this process can further remove impurities on the material surface and enhance the bonding force between the AlTiYO / CrAl coating and the substrate;

[0035] Then, raise the temperature of the vacuum chamber to 400 °C, and then perform short-time multi-arc ion plating of Cr with a pure Cr target in an argon atmosphere. The argon flow rate is 80 sccm, the substrate negative bias voltage is 100 V, the target current is 90 A, and the deposition time is 10 min. The purpose of this process is to deposit a multi-arc ion plating Cr underlayer to enhance the bonding force between the CrAl layer and the substrate or between the AlTiYO layer and the CrAl layer.

[0036] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0037] Through the AlTiYO / CrAl composite coating with a specific ratio and the corresponding multi-arc ion plating preparation process, the present invention realizes:

[0038] (1) On the premise that the composite coating is relatively thin (the thickness of the composite coating is about 6 μm), it has good lead-bismuth corrosion resistance. After static corrosion in liquid lead-bismuth alloy at 600 °C for 6000 h, no obvious coating peeling or corrosion is found, and the components of the coating still remain uniform after 6000 h of corrosion. It can be applied to the surface corrosion protection of structural steel in high-temperature (above 550 °C) liquid lead / lead-bismuth environments.

[0039] (2) The obtained AlTiYO / CrAl coating is very dense, has a low surface roughness, and a high bonding strength with the substrate surface. The bonding strength of the AlTiYO layer is greater than 1.5 N, and the bonding strength of the CrAl layer is greater than 7 N. Description of the Drawings

[0040] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can also be obtained based on these drawings without creative efforts. In the drawings:

[0041] Figure 1 is the scanning electron micrograph of the surface of the AlTiYO / CrAl coating sample prepared in Example 1, and (a) and (b) are the morphology diagrams of two different regions respectively.

[0042] Figure 2 is the scanning electron micrograph of the cross-section of the AlTiYO / CrAl coating sample prepared in Example 1.

[0043] Figure 3 is the cross-section SEM and EDS diagram of the AlTiYO / CrA coating sample prepared in Example 1, where (a-b) are the SEM morphology diagrams of two regions respectively, and (c) is the EDS line scan diagram.

[0044] Figure 4 is the SEM morphology after 100 thermal shock experiments of the AlTiYO / CrA coating prepared in Example 1.

[0045] Figure 5 is the three-dimensional morphology diagram of the surface of the AlTiYO / CrAl coating sample observed under a microscope in Example 1.

[0046] Figure 6It is a graph showing the bonding performance and friction coefficient test results of the AlTiYO / CrAl coating sample prepared in Example 1; the left graph is the state graph after the indenter scratches during the test, and the right graph is the friction coefficient test result graph.

[0047] Figure 7 It is a scanning electron microscope image and an EDS image of the cross-section of the AlTiYO / CrAl coating sample prepared in Example 1 after being corroded in a liquid lead-bismuth environment at 600 °C for 2000 hours; the upper graph is the morphology graph, and the lower graph is the line scan curve graph of Al, Ti, O, Cr, Fe, Pb, and Bi elements.

[0048] Figure 8 It is a scanning electron microscope image and an EDS image of the cross-section of the AlTiYO / CrAl coating sample prepared in Example 1 after being corroded in a liquid lead-bismuth environment at 600 °C for 4000 hours; the upper graph is the morphology graph, and the lower graph is the line scan curve graph of Al, Ti, O, Cr, Fe, Pb, and Bi elements.

[0049] Figure 9 It is a scanning electron microscope image and an EDS image of the cross-section of the AlTiYO / CrAl coating sample prepared in Example 1 after being corroded in a liquid lead-bismuth environment at 600 °C for 6000 hours; the upper graph is the morphology graph, and the lower graph is the line scan curve graph of Al, Ti, O, Cr, Fe, Pb, and Bi elements. Specific implementation manners

[0050] The following further describes the implementation manners of the present application in combination with examples. The following detailed descriptions of the examples are used to exemplarily illustrate the principles of the present application, but cannot be used to limit the scope of the present application, that is, the present application is not limited to the described examples.

[0051] The "ranges" disclosed in this application are defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of a particular range. The ranges defined in this way can include the end values or not include the end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, ranges of 60-110 and 80-120 are also contemplated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise specified, the numerical range "a-b" represents an abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been fully listed herein, and "0-5" is only an abbreviated representation of these numerical combinations. Additionally, when stating that a certain parameter is an integer ≥2, it is equivalent to disclosing that the parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0052] If there is no special instruction, all embodiments and optional embodiments of this application can be combined with each other to form a new technical solution.

[0053] If there is no special instruction, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0054] If there is no special instruction, all steps of this application can be carried out in sequence or randomly, preferably in sequence. For example, the method includes steps (a) and (b), which means that the method can include steps (a) and (b) carried out in sequence, or can also include steps (b) and (a) carried out in sequence. For example, when it is mentioned that the method may further include step (c), it means that step (c) can be added to the method in any order. For example, the method can include steps (a), (b), and (c), or can also include steps (a), (c), and (b), or can also include steps (c), (a), and (b), etc.

[0055] If there is no special instruction, the "including" and "comprising" mentioned in this application mean open-ended, and can also be closed-ended. For example, the "including" and "comprising" can mean that other components not listed can also be included or comprised, or can also mean that only the listed components are included or comprised.

[0056] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0057] Example 1:

[0058] In this example, an AlTiYO / CrAl coating resistant to high-temperature liquid lead / lead-bismuth alloy corrosion is prepared by multi-arc ion plating. Among them, the Al content in the CrAl coating is 6.3 wt%, and the specific preparation steps are as follows:

[0059] Step 1: After polishing the substrate material of structural steel (FeCrAl alloy) with sandpaper, white fused alumina with a particle size of 300 mesh is used for sandblasting. The sandblasting pressure is 0.3 MPa, the sandblasting distance is 150 mm, and the sandblasting time is 5 min. Subsequently, the substrate material is ultrasonically cleaned with acetone and anhydrous ethanol in turn for 10 min, and then taken out and dried for use;

[0060] Step 2: Place the pretreated substrate material in the vacuum chamber of the multi-arc ion plating equipment and fix the metal single target or alloy target. Then evacuate to 5×10 -3 Pa, and etch the surface of the sample in an argon atmosphere with a substrate negative bias voltage of 150 V;

[0061] Step 3: Raise the temperature of the vacuum chamber to 400 °C, and then perform short-time multi-arc ion plating of Cr with a pure Cr target in an argon atmosphere. The argon flow rate is 80 sccm, the substrate negative bias voltage is 100 V, the current of all four targets is 90 A, and the deposition time is 10 min;

[0062] Step 4: Subsequently, deposit a CrAl transition layer on the substrate simultaneously with three pure Cr targets and one CrAl target in an argon atmosphere. The argon flow rate is 80 sccm, the substrate negative bias voltage is 100 V, the target current is 90 A, and the deposition time is 2 h to obtain a CrAl coating; the composition of the CrAl target is: 30 wt% Al, 70 wt% Cr.

[0063] Step 5: Take out the sample after natural cooling, and then perform multi-arc ion plating of AlTiYO. When performing multi-arc ion plating of AlTiYO, an AlTiY alloy target is used. The composition of the AlTiY alloy target is 30 wt% Ti, 0.2 wt% Y, and the rest is Al. The oxygen flow rate is 130 sccm, the substrate negative bias voltage is 80 V, the target current is 95 A, and the deposition time is 2 h. The coating is naturally cooled to room temperature to obtain an AlTiYO / CrAl initial coating;

[0064] Step 6, after the coating is completed, place the AlTiYO / CrAl initial coating in an annealing furnace, evacuate to 1×10 -4 Pa, under an argon atmosphere, heat it up to 600 °C at a heating rate of 10 - 20 °C / min and hold for 6 h to obtain the AlTiYO / CrAl composite coating.

[0065] Example 2:

[0066] In this example, an AlTiYO / CrAl coating resistant to high-temperature liquid lead / lead-bismuth alloy corrosion is prepared by multi-arc ion plating. Among them, the Al content in the CrAl coating is 6.3 wt%, and the specific preparation steps are as follows:

[0067] Step 1, after polishing the substrate material of structural steel (low-activation ferritic martensitic steel) with sandpaper, perform sandblasting with white corundum with a particle size of 300 mesh. The sandblasting pressure is 0.3 MPa, the sandblasting distance is 150 mm, and the sandblasting time is 5 min. Subsequently, ultrasonically clean the substrate material with acetone and anhydrous ethanol in sequence for 10 min, and then take it out and dry it for use;

[0068] Step 2, place the pretreated substrate material in the vacuum chamber of the multi-arc ion plating equipment, fix the metal single-element target or alloy target, and then evacuate to 5×10 -3 Pa, etch the sample surface under an argon atmosphere, and the substrate negative bias voltage is 150 V;

[0069] Step 3, raise the temperature of the vacuum chamber to 400 °C, and then perform short-time multi-arc ion plating of Cr with a pure Cr target under an argon atmosphere. The argon flow rate is 80 sccm, the substrate negative bias voltage is 100 V, the target current is 90 A, and the deposition time is 10 min;

[0070] Step 4, then deposit a CrAl transition layer on the substrate simultaneously with three pure Cr targets and one CrAl target under an argon atmosphere. The argon flow rate is 80 sccm, the substrate negative bias voltage is 100 V, the currents of the four targets are all 90 A, and the deposition time is 2.5 h to obtain the CrAl coating; the composition of the CrAl target is: 35 wt% Al, 65 wt% Cr.

[0071] Step 5, take out the sample after natural cooling, and then perform multi-arc ion plating of AlTiYO. When performing multi-arc ion plating of AlTiYO, use an AlTiY alloy target. The composition of the AlTiY alloy target is 35 wt% Ti, 0.3 wt% Y, and the rest is Al. The oxygen flow rate is 130 sccm, the substrate negative bias voltage is 80 V, the target current is 95 A, and the deposition time is 2.5 h. The coating is naturally cooled to room temperature to obtain the AlTiYO / CrAl initial coating;

[0072] Step 6, after the coating is completed, place the AlTiYO / CrAl initial coating in an annealing furnace, evacuate to 1×10 -4 Pa, under an argon atmosphere, heat it at a heating rate of 10 - 20 °C / min to 580 °C and hold for 8 h to obtain the AlTiYO / CrAl composite coating.

[0073] Example 3:

[0074] In this example, an AlTiYO / CrAl coating resistant to high-temperature liquid lead / lead-bismuth alloy corrosion is prepared by multi-arc ion plating. Among them, the Al content in the CrAl coating is 6 wt%. The specific preparation steps are as follows:

[0075] Step 1, after polishing the substrate material of structural steel (FeCrAl alloy) with sandpaper, perform sandblasting with white fused alumina with a particle size of 300 mesh. The sandblasting pressure is 0.3 MPa, the sandblasting distance is 150 mm, and the sandblasting time is 5 min. Subsequently, ultrasonically clean the substrate material with acetone and anhydrous ethanol in sequence for 10 min, and then take it out and dry it for use;

[0076] Step 2, place the pretreated substrate material in the vacuum chamber of the multi-arc ion plating equipment and fix the metal single-element target or alloy target. Subsequently, evacuate to 5×10 -3 Pa, and etch the sample surface under an argon atmosphere with a substrate negative bias voltage of 150 V;

[0077] Step 3, raise the temperature of the vacuum chamber to 400 °C, and then perform short-time multi-arc ion plating of Cr with a pure Cr target under an argon atmosphere. The argon flow rate is 80 sccm, the substrate negative bias voltage is 100 V, the target current is 90 A, and the deposition time is 10 min;

[0078] Step 4, then deposit a CrAl transition layer on the substrate simultaneously with three pure Cr targets and one CrAl target under an argon atmosphere. The argon flow rate is 80 sccm, the substrate negative bias voltage is 100 V, the currents of the three Cr targets are all 90 A, the current of the CrAl target is 80 A, and the deposition time is 2.5 h to obtain the CrAl coating; the composition of the CrAl target is: 40 wt% Al, 60 wt% Cr.

[0079] Step 5, take out the sample after natural cooling, and then perform multi-arc ion plating of AlTiYO. When performing multi-arc ion plating of AlTiYO, use an AlTiY alloy target. The composition of the AlTiY alloy target is 30 wt% Ti, 0.5 wt% Y, and the rest is Al. The oxygen flow rate is 130 sccm, the substrate negative bias voltage is 80 V, the target current is 95 A, and the deposition time is 2.5 h. The coating is naturally cooled to room temperature to obtain the AlTiYO / CrAl initial coating;

[0080] Step 6, after the coating is completed, place the AlTiYO / CrAl initial coating in an annealing furnace, evacuate to 1×10 -4 Pa, under an argon atmosphere, heat it to 600 °C at a heating rate of 10 - 20 °C / min and hold for 8 h to obtain the AlTiYO / CrAl composite coating.

[0081] Example 4:

[0082] In this example, an AlTiYO / CrAl coating resistant to high-temperature liquid lead / lead-bismuth alloy corrosion is prepared by multi-arc ion plating. Among them, the Al content in the CrAl coating is 8 wt%, and the specific preparation steps are as follows:

[0083] Step 1, after polishing the substrate material of structural steel (FeCrAl alloy) with sandpaper, perform sandblasting treatment with white corundum with a particle size of 300 mesh. The sandblasting pressure is 0.3 MPa, the sandblasting distance is 150 mm, and the sandblasting time is 5 min. Subsequently, ultrasonically clean the substrate material with acetone and anhydrous ethanol in turn for 10 min, and then take it out and dry it for use;

[0084] Step 2, place the pretreated substrate material in the vacuum chamber of the multi-arc ion plating equipment, and fix the metal elemental target or alloy target. Subsequently, evacuate to 5×10 -3 Pa, etch the sample surface under an argon atmosphere, and the substrate negative bias voltage is 150 V;

[0085] Step 3, raise the temperature of the vacuum chamber of the multi-arc ion plating equipment to 400 °C, and then perform short-term multi-arc ion plating of Cr with a pure Cr target under an argon atmosphere. The argon flow rate is 80 sccm, the substrate negative bias voltage is 100 V, the target current is 90 A, and the deposition time is 10 min;

[0086] Step 4, then deposit a CrAl transition layer on the substrate simultaneously with three pure Cr targets and one CrAl target under an argon atmosphere. The argon flow rate is 80 sccm, the substrate negative bias voltage is 100 V, the currents of the three Cr targets are all 87 A, the current of the CrAl target is 90 A, and the deposition time is 3 h to obtain the CrAl coating; the composition of the CrAl target is: 30 wt% Al, 70 wt% Cr.

[0087] Step 5, take out the sample after natural cooling, and then perform multi-arc ion plating of AlTiYO. When performing multi-arc ion plating of AlTiYO, an AlTiY alloy target is used. The composition of the AlTiY alloy target is 35 wt% Ti, 0.4 wt% Y, and the rest is Al. The oxygen flow rate is 130 sccm, the substrate negative bias voltage is 80 V, the target current is 95 A, the deposition time is 3 h, and the coating is naturally cooled to room temperature to obtain the AlTiYO / CrAl initial coating;

[0088] Step 6, after the coating is completed, place the AlTiYO / CrAl initial coating in an annealing furnace, evacuate to 1×10 -4 Pa, and under an argon atmosphere, heat it to 600 °C at a heating rate of 10 - 20 °C / min and hold for 8 h to obtain the AlTiYO / CrAl composite coating.

[0089] Example 5:

[0090] In this example, an AlTiYO / CrAl coating resistant to high-temperature liquid lead / lead-bismuth alloy corrosion is prepared by multi-arc ion plating. Among them, the Al content in the CrAl coating is 5 wt%. The specific preparation steps are as follows:

[0091] Step 1, after using sandpaper to polish the substrate material of structural steel (FeCrAl alloy), perform sandblasting with white corundum with a particle size of 300 mesh. The sandblasting pressure is 0.3 MPa, the sandblasting distance is 150 mm, and the sandblasting time is 5 min. Then, ultrasonically clean the substrate material with acetone and absolute ethanol in turn for 10 min, and then take it out and dry it for use;

[0092] Step 2, place the pretreated substrate material in the vacuum chamber of the multi-arc ion plating equipment, fix the metal elemental target or alloy target, and then evacuate to 5×10 -3 Pa, and etch the sample surface under an argon atmosphere, with the substrate negative bias voltage being 150 V;

[0093] Step 3, raise the temperature of the equipment vacuum chamber to 400 °C, and then perform short-time multi-arc ion plating of Cr under an argon atmosphere with a pure Cr target. The argon flow rate is 80 sccm, the substrate negative bias voltage is 100 V, the target current is 90 A, and the deposition time is 10 min;

[0094] Step 4, then deposit a CrAl transition layer on the substrate simultaneously with three pure Cr targets and one CrAl target under an argon atmosphere. The argon flow rate is 100 sccm, the substrate negative bias voltage is 100 V, the current of each of the three Cr targets is 110 A, the current of the CrAl target is 90 A, and the deposition time is 1.5 h to obtain the CrAl coating; the composition of the CrAl target is: 38 wt% Al, 62 wt% Cr.

[0095] Step 5: After the sample is naturally cooled, take it out and then perform multi-arc ion plating of AlTiYO. When performing multi-arc ion plating of AlTiYO, an AlTiY alloy target is used. The composition of the AlTiY alloy target is 30 wt% Ti, 0.2 wt% Y, and the rest is Al. The oxygen flow rate is 130 sccm, the substrate negative bias voltage is 80 V, the target current is 95 A, the deposition time is 2 h, and the coating is naturally cooled to room temperature to obtain the AlTiYO / CrAl initial coating;

[0096] Step 6: After the coating is finished, place the AlTiYO / CrAl initial coating in an annealing furnace, evacuate to 1×10 -4 Pa, and under an argon atmosphere, heat it to 600 °C at a heating rate of 10 - 20 °C / min and hold for 6 h to obtain the AlTiYO / CrAl composite coating.

[0097] Performance test:

[0098] Analyze the morphology and elements of the composite coating obtained in Example 1, and respectively obtain Figure 1 , 2 , and 3 results. From the Figure 1 SEM morphology diagram, it can be seen that the obtained AlTiYO / CrAl coating is very dense, and there are no holes and cracks on the surface. From Figure 5 , it can be seen that the obtained coating has a low roughness. From the Figure 2 morphology diagram of the sample cross-section, it can be seen that the thickness of CrAl is about 3.64 microns, and the thickness of AlTiYO is 3.18 microns. The overall thickness of this coating is relatively thin. From Figure 3 the cross-section SEM and EDS of the coating sample, it can be seen that the surface compactness of the coating is good, there are no holes and cracks, and EDS shows that a composite coating AlTiYO / CrAl with Al, Ti, and O as the surface layer (where the Y element content in the AlTiYO layer is too low to be detected) and Cr, Al as the intermediate layer is formed by this method.

[0099] The inventor conducted a thermal shock experiment on the coating. After 100 thermal shock experiments, the obtained SEM image is shown in Figure 4 . From Figure 4 , it can be seen that after the thermal shock experiment, the surface of the coating is still dense, and there are no holes and cracks, indicating that there is no coating peeling or corrosion.

[0100] The inventor used a KEYENCE VK-X150 type laser microscope to observe the three-dimensional morphology of the coating surface and measure the surface roughness of the coating. From the Figure 5 optical profilometry of the coating sample surface, the surface roughness of the coating is Ra = 0.848 μm, and the roughness is relatively low.

[0101] The inventor used an Anton Paar NHT+MCT type micro scratch tester to test the bonding performance and friction coefficient of the coating. During the scratch process, a progressive load loading mode was adopted. The initial value of the load on the indenter was 0.03 N, which linearly increased to 20 N at a rate of 5 N / min, and the data sampling frequency was 30 Hz. The degree of damage and peeling of the coating was judged based on the sudden change in the scratch depth of the indenter during the test. Combining with the optical microscope images, the indenter load at the time of coating peeling was used as the coating adhesion force. Figure 6 The micro scratch test results are shown. The average of the three test results of the AlTiYO / CrAl coating adhesion force is 15.73 N.

[0102] The inventor further conducted an anti-corrosion test on the sample in a liquid lead-bismuth environment at 600 °C. The morphology diagrams and EDS diagrams after corrosion tests after 2000 hours, 4000 hours, and 6000 hours are shown in Figure 7 , 8 , and Figure 9. It can be seen that at 600 °C, after being corroded by the lead-bismuth alloy for up to 6000 hours, the surface of the composite coating of the present invention is still dense, without holes and cracks. X-ray EDS energy spectrum analysis also shows that the components of the AlTiYO / CrAl coating are uniform.

[0103] The above specific implementation manners further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific implementation manners of the present invention and are not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A composite coating resistant to high-temperature corrosion by liquid lead / lead-bismuth alloy, characterized in that, The composite coating is an AlTiYO / CrAl coating, with CrAl as the coating transition layer, and the AlTiYO / CrAl coating is deposited on a structural steel substrate.

2. The composite coating resistant to corrosion by high-temperature liquid lead / lead-bismuth alloy according to claim 1, wherein The thickness of the composite coating is 6 - 10 microns.

3. The composite coating resistant to high-temperature corrosion of liquid lead / lead-bismuth alloy according to claim 1, wherein The content of Al in the CrAl transition layer is 5 - 8 wt%.

4. A composite coating resistant to high-temperature corrosion by liquid lead / lead-bismuth alloy according to claim 1, characterized in that, The coefficient of thermal expansion of the CrAl transition layer is (8 - 11.7)×10 -6 / K.

5. A composite coating resistant to high-temperature corrosion by liquid lead / lead-bismuth alloy according to claim 1, characterized in that, The structural steel is a FeCrAl alloy substrate or a low-activation ferritic or martensitic steel.

6. A method for preparing a composite coating resistant to corrosion by high-temperature liquid lead / lead-bismuth alloy, according to any one of claims 1 to 5, characterized in that, The AlTiYO / CrAl coating is prepared by multi-arc ion plating.

7. The preparation method of a composite coating resistant to high-temperature corrosion by liquid lead / lead-bismuth alloy according to claim 6, characterized in that, It includes the following steps: (1) Pretreat the substrate material of the structural steel. (2) Use CrAl as the coating transition layer, and deposit the CrAl transition layer on the substrate simultaneously with a pure Cr target and a CrAl target in an argon atmosphere. Stop coating after the coating thickness reaches the set thickness to obtain a CrAl coating. (3) After natural cooling, perform multi-arc ion plating of AlTiYO with an AlTiY alloy target. End coating after the coating deposited on the substrate surface reaches the set thickness, and let the coating cool naturally to room temperature to obtain an AlTiYO / CrAl initial coating. (4) After the coating is finished, place the AlTiYO / CrAl initial coating in an annealing furnace, evacuate to 1×10 -4 Pa, and under an argon atmosphere, heat it at a heating rate of 10 - 20 °C / min to 300 - 600 °C and hold for 6 - 8 h to obtain the AlTiYO / CrAl composite coating.

8. The preparation method of a composite coating resistant to high-temperature corrosion by liquid lead / lead-bismuth alloy according to claim 6, characterized in that In step (2), 3 pure Cr targets and 1 CrAl target are used. The composition of the CrAl target is 30 - 50 wt% Al and 50 - 70 wt% Cr.

9. The preparation method of a composite coating resistant to high-temperature corrosion by liquid lead / lead-bismuth alloy according to claim 6, characterized in that, In step (2), when depositing the CrAl transition layer, the argon flow rate is 80 - 150 sccm, the substrate negative bias voltage is 80 - 150 V, the target current is 80 - 120 A, and the deposition time is 2 - 10 h.

10. The preparation method of a composite coating resistant to high-temperature corrosion by liquid lead / lead-bismuth alloy according to claim 6, characterized in that, In step (3), the composition of the AlTiY alloy target is 30 - 50 wt% Ti, 0.2 - 0.5 wt% Y, and the rest is Al.

11. The preparation method of a composite coating resistant to high-temperature corrosion by liquid lead / lead-bismuth alloy according to claim 6, characterized in that In step (3), the conditions for multi-arc ion plating of AlTiYO are: the oxygen flow rate is 110 - 150 sccm, the substrate negative bias voltage is 80 - 120 V, the target current is 80 - 100 A, and the deposition time is 1 - 5 h.

12. The preparation method of a composite coating resistant to high-temperature corrosion by liquid lead / lead-bismuth alloy according to any one of claims 6 to 10, characterized in that, The pretreatment in step (1) is: grind or sandblast the surface of the structural steel, then perform ultrasonic cleaning with anhydrous ethanol and acetone in sequence, and then take it out and dry for use.

13. A method for preparing a composite coating resistant to high-temperature corrosion by liquid lead / lead-bismuth alloy, according to any one of claims 6 to 10, characterized in that, After pretreating the substrate material, it also includes the following process: Place the pre-treated substrate material in the vacuum chamber of a multi-arc ion plating equipment, evacuate the vacuum to 5×10 -3 Pa, etch the surface of the sample in an argon atmosphere, and the substrate negative bias voltage is 150V; Raise the temperature of the vacuum chamber to 400 °C, and then perform short-time multi-arc ion plating of Cr with a pure Cr target in an argon atmosphere. The argon flow rate is 80 sccm, the substrate negative bias voltage is 100 V, the target current is 90 A, and the deposition time is 10 min.

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