Lead-bismuth-resistant coating and preparation method thereof

Abstract

The invention relates to the technical field of material protection, in particular to a lead-bismuth-resistant coating and a preparation method thereof.The coating is composed of a metal bonding layer, a functional transition layer and a corrosion-resistant layer, the metal bonding layer is formed by compounding a high-entropy alloy and a medium-entropy alloy, a component gradient transition structure is formed, the high-entropy alloy is a near-equal-atomic-ratio alloy of Fe, Co, Ni, Cr and Al, and the medium-entropy alloy is a near-equal-atomic-ratio alloy of Fe, Co, Ni, Cr and Al. %, and the medium-entropy alloy is a FeCoNiCr system quaternary alloy, and the content of the Al element is 5-10 at. The functional transition layer is a transition metal nitride layer; and the corrosion-resistant layer is an eutectic composite layer of rare earth oxide and stabilized oxide. Therefore, the problems of insufficient bonding strength, limited corrosion resistance, poor process stability and the like in the prior art are solved.

Description

Technical Field

[0001] The present application relates to the technical field of material protection, and in particular to a lead-resistant bismuth coating and a preparation method thereof. Background Art

[0002] Liquid metal lead-bismuth eutectic alloy has excellent neutronic properties, high boiling point and good thermal conductivity. However, its high-temperature liquid state poses a severe challenge to traditional structural materials such as austenitic stainless steel. The liquid metal corrosion phenomenon caused by it can cause rapid dissolution of the material surface, forming a brittle intermetallic compound layer, and ultimately causing mechanical failure.

[0003] Existing corrosion-resistant coatings have the following problems: there is a significant difference in thermal expansion coefficients between the ceramic coating and the metal substrate, which generates residual stress during the thermal cycle and causes cracking or even peeling of the coating; a single-layer structure is difficult to simultaneously meet the multiple requirements of anti-penetration, corrosion resistance, and thermal shock resistance; traditional thermal spraying, magnetron sputtering and other technologies are difficult to accurately control the composition gradient and grain boundary structure, and defects such as pores and cracks are easily formed inside the coating, which becomes a fast channel for the penetration of corrosive media. Summary of the invention

[0004] The present application provides a lead-bismuth resistant coating and a preparation method thereof to solve the problems of insufficient bonding strength, limited corrosion resistance, and poor process stability in the prior art.

[0005] An embodiment of the present application provides a lead-bismuth resistant coating, which consists of a metal bonding layer, a functional transition layer and a corrosion-resistant layer, wherein the metal bonding layer is composed of a high-entropy alloy and a medium-entropy alloy composite to form a composition gradient transition structure, the high-entropy alloy is a nearly equiatomic ratio alloy of Fe, Co, Ni, Cr, and Al, and the Al element content is 5-10at.%, and the medium-entropy alloy is a quaternary alloy of FeCoNiCr; the functional transition layer is a transition metal nitride layer; and the corrosion-resistant layer is a eutectic composite layer of rare earth oxides and stabilized oxides.

[0006] Optionally, the volume ratio of the high entropy alloy to the medium entropy alloy is (3:1)-(1:1), the high entropy alloy component is FeCoNiCrAl, and the medium entropy alloy component is FeCoNiCr.

[0007] Optionally, the transition metal nitride layer is a nano-multilayer superlattice structure formed by alternately depositing TiAlN and CrZrN, wherein the single layer thickness of the nano-multilayer superlattice structure is 10-50 nm, and the total thickness is 80-150 nm.

[0008] Optionally, the thickness ratio of the TiAlN layer to the CrZrN layer is (1:2)-(2:1), and the nitrogen vacancy concentration in the CrZrN layer is 5-15%.

[0009] Optionally, the rare earth oxide is Y2O3, and the stabilized oxide is ZrO2 and CeO2, wherein the molar ratio of Y2O3 to CeO2 is 1:(0.2-0.8), and ZrO2 exists in a tetragonal stabilized form.

[0010] Optionally, the Y2O3-ZrO2-CeO2 eutectic oxide in the corrosion-resistant layer generates a Ta-Zr-OC interface phase through an in-situ reaction, and the Ta-Zr-OC interface phase is distributed between layers in the form of nanoparticles with a particle size of 20-100 nm.

[0011] The present application also proposes a method for preparing a lead-bismuth resistant coating, comprising the following steps: Step 1: depositing a metal bonding layer on the surface of the substrate by a plasma spraying-physical vapor deposition composite process, wherein the plasma spraying power is 30-50 kW, the spraying distance is 80-120 mm, and the substrate preheating temperature is ≤400°C; Step 2: depositing a TiAlN / CrZrN superlattice functional transition layer on the metal bonding layer by high-power pulsed magnetron sputtering technology, wherein the pulse frequency is 500-1000 Hz and the duty cycle is 1-3%; Step three: Use laser-assisted chemical vapor deposition to form a corrosion-resistant layer on the surface of the functional transition layer, wherein the laser power is 200-500W, the deposition temperature is 600-800°C, and the precursor is a mixed solution of Y(C5H7O2)3, ZrCl4 and Ce(NO3)3.

[0012] Optionally, argon gas is introduced during the physical vapor deposition process, wherein the pressure is 0.5-2Pa and the bias voltage is -50 to -150V.

[0013] Optionally, the high entropy alloy and the medium entropy alloy in the metal bonding layer are alternately sprayed to achieve a composition gradient transition, and laser nitriding treatment is performed after each layer is sprayed, the laser scanning rate is 2-5 mm / s, and the depth of the nitrided layer is 5-20 μm.

[0014] Optionally, the corrosion-resistant layer is subjected to amorphous laser remelting treatment, and the laser power density is 5×10 2 -8×10³W / cm², scanning speed is 10-50mm / s, forming a nanocrystalline-amorphous composite structure with a surface porosity of <0.5%.

[0015] Therefore, this application has at least the following beneficial effects: In the embodiment of the present application, the metal bonding layer is made of high entropy alloy and medium entropy alloy to form a composition gradient transition structure. The multi-principal element synergistic effect of the high entropy alloy produces strong lattice distortion and enhances the interatomic bonding force; the stable crystal structure of the medium entropy alloy reduces the interface stress. Through the composition gradient design, the thermal expansion coefficients of the substrate and the coating are gradually matched, the stress concentration caused by the expansion difference during the thermal cycle is reduced, and the bonding strength between the coating and the substrate is significantly improved, thereby avoiding the coating from peeling off; The TiAlN / CrZrN nano multilayer superlattice structure of the functional transition layer in the embodiment of the present application forms a large number of interfaces through alternating deposition. The high hardness and oxidation resistance of TiAlN and the corrosion resistance of CrZrN work together, and the dislocation interaction at the interface hinders the penetration path of the lead-bismuth corrosive medium; at the same time, the 5-15% nitrogen vacancies in the CrZrN layer can adsorb active ions in the corrosive medium, reduce its diffusion ability, form a dual corrosion resistance mechanism, and rapidly reduce the penetration rate of the corrosive medium; In the embodiment of the present application, the corrosion-resistant layer is regulated by the electronic structure of rare earth elements to promote the stable existence of ZrO2 in the tetragonal phase, and the phase transformation toughening effect of ZrO2 is used to absorb the crack propagation energy; at the same time, the in-situ generated Ta-Zr-OC nano-interface phase is evenly distributed between the layers, and the growth of oxide grains is inhibited by the pinning effect, so that the oxidation resistance of the coating in the lead-bismuth environment is improved; The embodiment of the present application forms a gradient protection system through a metal bonding layer, a functional transition layer, and a corrosion-resistant layer, wherein the metal bonding layer lays the foundation for bonding, the functional transition layer blocks the corrosive medium, and the corrosion-resistant layer directly resists oxidative corrosion, thereby extending the comprehensive corrosion-resistant life of the coating in a lead-bismuth environment; In the preparation method of the embodiment of the present invention, plasma spraying-physical vapor deposition reduces the porosity of the metal bonding layer by precisely controlling parameters; high-power pulsed magnetron sputtering can achieve dense deposition of the functional transition layer; laser-assisted chemical vapor deposition combined with amorphous laser remelting makes the surface porosity of the corrosion-resistant layer less than 0.5%, thereby improving process stability.

[0016] Thereby, the problems of insufficient bonding strength, limited corrosion resistance, and poor process stability in the prior art are solved.

[0017] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which: Figure 1 A structural diagram of a lead-resistant bismuth coating provided according to an embodiment of the present application; Figure 2A flow chart of a method for preparing a lead-resistant bismuth coating according to an embodiment of the present application; Figure 3 A peak diagram of XDR of a lead-bismuth resistant coating provided according to an embodiment of the present application; Figure 4 This is a scanning electron microscope image of the lead-resistant bismuth coating provided according to Example 1 of the present application; Figure 5 This is a scanning electron microscope image of the lead-resistant bismuth coating provided according to Example 2 of the present application; Figure 6 This is a scanning electron microscope image of the lead-resistant bismuth coating provided according to Example 3 of the present application; Figure 7 Schematic diagram of DSC-TGA provided according to Example 2 of the present application. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments; based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present application.

[0020] In the examples of the present application, unless otherwise specified, raw materials or processing techniques are conventional commercially available raw materials or conventional processing techniques in the art.

[0021] The present application is described below with reference to specific embodiments. It should be noted that these embodiments are merely illustrative and do not limit the present application in any way. Example

[0022] The present application provides a lead-bismuth resistant coating, such as Figure 1 As shown, the coating consists of a metal bonding layer, a functional transition layer and a corrosion-resistant layer, wherein the metal bonding layer is composed of a high entropy alloy and a medium entropy alloy to form a composition gradient transition structure, the high entropy alloy is a nearly equiatomic alloy of Fe, Co, Ni, Cr, and Al, and the Al element content is 5at.%, the medium entropy alloy is a quaternary alloy of FeCoNiCr; the functional transition layer is a transition metal nitride layer; the corrosion-resistant layer is a eutectic composite layer of rare earth oxides and stabilized oxides.

[0023] Among them, the volume ratio of high entropy alloy to medium entropy alloy is 3:1, the composition of high entropy alloy is FeCoNiCrAl, and the composition of medium entropy alloy is FeCoNiCr.

[0024] The transition metal nitride layer is a nano multilayer superlattice structure formed by alternately depositing TiAlN and CrZrN, wherein the single layer thickness of the nano multilayer superlattice structure is 10-50nm and the total thickness is 80-150nm.

[0025] The thickness ratio of the TiAlN layer to the CrZrN layer is 1:2, and the nitrogen vacancy concentration in the CrZrN layer is 5%.

[0026] The rare earth oxide is Y2O3, and the stabilized oxides are ZrO2 and CeO2, wherein the molar ratio of Y2O3 to CeO2 is 1:0.2, and ZrO2 exists in a tetragonal stabilized form.

[0027] Among them, the Y2O3-ZrO2-CeO2 eutectic oxide in the corrosion-resistant layer generates a Ta-Zr-OC interface phase through an in-situ reaction. The Ta-Zr-OC interface phase is distributed between layers in the form of nanoparticles with a particle size of 20-100nm.

[0028] The present application also proposes a method for preparing a lead-bismuth-resistant coating, such as Figure 2 As shown, the following steps are included: Step 1: A plasma spraying-physical vapor deposition composite process is used to deposit a metal bonding layer on the substrate surface, wherein the plasma spraying power is 30-50kW, the spraying distance is 80-120mm, and the substrate preheating temperature is ≤400°C.

[0029] Argon gas is introduced during the physical vapor deposition process, wherein the pressure is 0.5-2 Pa, the bias voltage is -50 to -150 V, and the substrate contains Ta elements.

[0030] It can be understood that the embodiment of the present application achieves multi-dimensional performance optimization of the metal bonding layer through the coordinated regulation of plasma spraying and physical vapor deposition: a supersonic flame flow is combined with a spraying distance of 80-120mm to form a dense flat structure with a porosity of <1.5%; a gradient control strategy of substrate preheating temperature ≤400°C is adopted to effectively eliminate thermal residual stress (reduction >35%) and avoid substrate phase change, providing an ideal interface foundation with high bonding strength for subsequent coatings.

[0031] In an embodiment of the present application, the high entropy alloy and the medium entropy alloy in the metal bonding layer are alternately sprayed to achieve a composition gradient transition, and laser nitriding treatment is performed after each layer is sprayed. The laser scanning rate is 2-5 mm / s, and the depth of the nitriding layer is 5-20 μm.

[0032] It can be understood that the embodiment of the present application constructs a composition gradient transition structure through the alternating spraying process of high entropy alloy and medium entropy alloy. After each layer is sprayed, a nitriding treatment with a laser scanning rate of 2-5mm / s is used to form a 5-20μm deep diffusion nitriding layer on the surface. The multi-principal element synergistic effect of the high entropy alloy is used to enhance the grain boundary bonding force, and the stable crystal structure of the medium entropy alloy reduces the interface stress, so that the thermal expansion coefficient presents a smooth gradient transition, which effectively relieves the thermal cycle stress; the supersaturated nitrogen solid solution produced by laser nitridation forms a composite strengthening phase with the intermetallic compound, and the surface hardness is increased by 30-50%. At the same time, the nitriding layer acts as a diffusion barrier to significantly inhibit the penetration of the corrosive medium along the grain boundary, so that the bonding strength of the metal bonding layer is improved, which is 50% higher than that of the traditional process, and the porosity is controlled at <1%, providing a reliable thermal-mechanical matching interface for long-term service.

[0033] Step 2: Depositing a TiAlN / CrZrN superlattice functional transition layer on the metal bonding layer by high-power pulsed magnetron sputtering technology, wherein the pulse frequency is 500-1000 Hz and the duty cycle is 10-30%.

[0034] It is understandable that the embodiment of the present application adopts high-frequency pulsed magnetron sputtering technology, and realizes atomic-level periodic deposition of TiAlN and CrZrN through high-density plasma bombardment with ion kinetic energy > 20eV, forming a nano-superlattice structure. This structure produces a dislocation mirror effect through a coherent interface, significantly improving the mechanical strengthening effect. In terms of corrosion resistance, the TiAlN layer provides a hardness of > 25GPa and high-temperature oxidation resistance of 1100°C. The controllable nitrogen vacancies in the CrZrN layer serve as active sites, selectively capturing corrosion ions such as Bi³⁺ in the Pb-Bi environment, forming a synergistic protection mechanism of "physical barrier + chemical passivation", which reduces the permeability of the corrosive medium by 90% compared with traditional single-layer coatings. The optimization of process parameters makes the coating density > 99%, and the deposition rate reaches 2-5μm / h, achieving efficient and precise preparation. The superlattice interface effectively hinders the cross-layer movement of dislocations at high temperatures, and the steady-state creep rate at 1100°C is <1×10⁻ 8 s⁻¹, the creep resistance is 5 times higher than that of conventional coatings, showing excellent thermal-mechanical coupling service stability.

[0035] Step 3: Use laser-assisted chemical vapor deposition to form a corrosion-resistant layer on the surface of the functional transition layer, wherein the laser power is 200-500W, the deposition temperature is 600-800°C, and the precursor is a mixed solution of Y(C5H7O2)3, ZrCl4 and Ce(NO3)3.

[0036] It can be understood that the embodiment of the present application innovatively constructs a Y2O3-ZrO2-CeO2 multiphase synergistic corrosion-resistant layer on the surface of the functional transition layer through laser-assisted chemical vapor deposition technology. Using 200-500W laser power and 600-800℃ deposition temperature synergistically, laser photons selectively excite Y(C5H7O2)3, ZrCl4 and Ce(NO3)3 precursors, and in situ generate 5-20nm nanocrystalline oxides on the substrate surface, forming a dense columnar structure with a porosity of <1%. Y2O3 acts as a stabilizer for cubic ZrO2 to inhibit high-temperature phase change, CeO2's oxygen storage capacity enables the oxide layer to self-repair, and the ZrO2 main crystal phase provides a structural skeleton. The three work together to reduce the corrosion rate of the coating in molten Pb-Bi at 700℃. The interaction between the laser and the substrate produces a heat-affected zone of <10μm, which promotes diffusion bonding, while the micro-melting effect eliminates pore defects.

[0037] During the laser-assisted chemical vapor deposition process, Y(C5H7O2)3 is pyrolyzed to generate Y2O3, ZrCl4 reacts with O2 to generate ZrO2, Ce(NO3)3 is decomposed to generate CeO2, and Ta element diffuses to form Ta-Zr-OC interface phase. The reaction formula is: 2Y(C5H7O2)3+36O2→Y2O3+30CO2+21H2O; ZrCl4+O2→ZrO2+2Cl2↑; 2Ce(NO3)3→2CeO2+6NO2↑+O2↑.

[0038] In the embodiment of the present application, the corrosion-resistant layer is subjected to an amorphous laser remelting treatment, the laser power density is 900 W / cm², the scanning speed is 10-50 mm / s, and a nanocrystalline-amorphous composite structure with a surface porosity of less than 0.5% is formed.

[0039] It is understandable that the embodiment of the present application adopts amorphous laser remelting technology. Through the instantaneous action of laser and material surface, a nanocrystalline / amorphous gradient composite structure is constructed on the surface of the corrosion-resistant layer, and the surface porosity is reduced from 1% of the original coating to <0.5% by using the rapid melting effect, forming a densified barrier layer, which effectively blocks the penetration channel of the corrosive medium. The amorphous phase significantly improves the pitting resistance and uniform corrosion performance by eliminating grain boundary defects, and the residual nanocrystals as a dispersed strengthening phase increase the surface hardness to 12-15GPa. Laser-induced element diffusion promotes Y³⁺, ​​Zr 4 ⁺, Ce³⁺ are evenly distributed, enhancing the multi-component synergistic effect, reducing the corrosion rate in a 700℃ molten Pb-Bi environment to <0.2μm / year. At the same time, the atomic-level transition layer formed between the remelting zone and the matrix significantly reduces the risk of stress concentration. Example

[0040] The present application provides a lead-bismuth resistant coating, such as Figure 1 As shown, the coating consists of a metal bonding layer, a functional transition layer and a corrosion-resistant layer, wherein the metal bonding layer is composed of a high entropy alloy and a medium entropy alloy to form a composition gradient transition structure, the high entropy alloy is a nearly equiatomic alloy of Fe, Co, Ni, Cr, and Al, and the Al element content is 8at.%, the medium entropy alloy is a quaternary alloy of FeCoNiCr; the functional transition layer is a transition metal nitride layer; and the corrosion-resistant layer is a eutectic composite layer of rare earth oxides and stabilized oxides.

[0041] Among them, the volume ratio of high entropy alloy to medium entropy alloy is 2:1, the composition of high entropy alloy is FeCoNiCrAl, and the composition of medium entropy alloy is FeCoNiCr.

[0042] The transition metal nitride layer is a nano multilayer superlattice structure formed by alternately depositing TiAlN and CrZrN, wherein the single layer thickness of the nano multilayer superlattice structure is 10-50nm and the total thickness is 80-150nm.

[0043] The thickness ratio of the TiAlN layer to the CrZrN layer is 1:1, and the nitrogen vacancy concentration in the CrZrN layer is 5-15%.

[0044] Among them, the rare earth oxide is Y2O3, and the stabilized oxides are ZrO2 and CeO2, wherein the molar ratio of Y2O3 to CeO2 is 1:0.5, and ZrO2 exists in a tetragonal stabilized form.

[0045] Among them, the Y2O3-ZrO2-CeO2 eutectic oxide in the corrosion-resistant layer generates a Ta-Zr-OC interface phase through an in-situ reaction. The Ta-Zr-OC interface phase is distributed between layers in the form of nanoparticles with a particle size of 20-100nm.

[0046] The preparation method of the present embodiment is the same as that of Example 1. Example

[0047] The present application provides a lead-bismuth resistant coating, such as Figure 1 As shown, the coating consists of a metal bonding layer, a functional transition layer and a corrosion-resistant layer, wherein the metal bonding layer is composed of a high entropy alloy and a medium entropy alloy to form a composition gradient transition structure, the high entropy alloy is a nearly equiatomic alloy of Fe, Co, Ni, Cr, and Al, and the Al element content is 10at.%, the medium entropy alloy is a quaternary alloy of FeCoNiCr; the functional transition layer is a transition metal nitride layer; and the corrosion-resistant layer is a eutectic composite layer of rare earth oxides and stabilized oxides.

[0048] Among them, the volume ratio of high entropy alloy to medium entropy alloy is 1:1, the composition of high entropy alloy is FeCoNiCrAl, and the composition of medium entropy alloy is FeCoNiCr.

[0049] The transition metal nitride layer is a nano multilayer superlattice structure formed by alternately depositing TiAlN and CrZrN, wherein the single layer thickness of the nano multilayer superlattice structure is 10-50nm and the total thickness is 80-150nm.

[0050] The thickness ratio of the TiAlN layer to the CrZrN layer is 1:1, and the nitrogen vacancy concentration in the CrZrN layer is 15%.

[0051] Among them, the rare earth oxide is Y2O3, and the stabilized oxides are ZrO2 and CeO2, wherein the molar ratio of Y2O3 to CeO2 is 1:0.8, and ZrO2 exists in a tetragonal stabilized form.

[0052] Among them, the Y2O3-ZrO2-CeO2 eutectic oxide in the corrosion-resistant layer generates a Ta-Zr-OC interface phase through an in-situ reaction. The Ta-Zr-OC interface phase is distributed between layers in the form of nanoparticles with a particle size of 20-100nm.

[0053] The preparation method of the present embodiment is the same as that of Example 1.

[0054] Comparative Example 1 This comparative example provides a lead-bismuth resistant coating and a preparation method thereof, which differs from Example 1 only in that the coating structure does not include a functional transition layer, and the reduced amount of the functional transition layer is distributed to the corrosion-resistant layer; in addition, the deposition step of the functional transition layer is reduced in the preparation method, and the corrosion-resistant layer is directly formed on the metal bonding layer by laser-assisted chemical vapor deposition. The remaining components, component contents, and preparation process are the same as those in Example 1.

[0055] Comparative Example 2 This comparative example provides a lead-bismuth-resistant coating and a preparation method thereof, which differs from Example 1 only in that the metal bonding layer does not include a composition gradient transition structure, and the metal bonding layer adopts a single high-entropy alloy or a medium-entropy alloy, or a simple mixture of the high-entropy alloy and the medium-entropy alloy, and does not form a composition gradient transition structure; in addition, when the metal bonding layer is deposited, alternating spraying and laser nitriding treatment are not performed to achieve a composition gradient, but a one-time spraying or deposition is completed, and the remaining components, component contents, and preparation process are the same as those in Example 1.

[0056] Comparative Example 3 This comparative example provides a lead-bismuth resistant coating and a preparation method thereof, which differs from Example 1 only in that during the laser-assisted chemical vapor deposition of the corrosion-resistant layer, the laser power is reduced to 150 W, the deposition temperature is adjusted to 500°C, the laser action time is shortened, the occurrence of in-situ reaction is suppressed, and the in-situ reaction to form a Ta-Zr-OC interface phase is avoided. The preparation steps and parameters of the metal bonding layer and the functional transition layer are the same as those in Example 1.

[0057] The phase analysis of the lead-resistant bismuth coatings prepared in Examples 1-3 and Comparative Examples 1-3 was performed using an X-ray diffractometer. All samples showed consistent diffraction peak positions and no impurity peaks appeared, indicating that high-purity coatings were successfully prepared. Figure 3 As shown, the diffraction peak intensity of the sample in Example 2 is the highest and the crystal integrity is the best; therefore, the samples prepared in Examples 1-3 and Comparative Examples 1-3 are tested for bonding strength, corrosion resistance, oxidation resistance and porosity, respectively. The performance tests are shown in Table 1 below.

[0058] Table 1 Performance test of lead-bismuth resistant coating Material Bonding strength (MPa) Lead-bismuth corrosion weight loss rate (mg / cm²) Antioxidant weight gain (mg / cm²) Porosity% Example 1 68 0.25 0.11 0.6 Example 2 70 0.28 0.13 0.8 Example 3 69 0.26 0.12 0.7 Comparative Example 1 46 0.70 0.18 2.3 Comparative Example 2 35 0.55 0.20 3.5 Comparative Example 3 59 0.45 0.33 1.9 like Figure 4 , Figure 5 , Figure 6 As shown in Table 1, the lead-bismuth resistant coating in the embodiment of the present invention has excellent properties such as strong bonding strength, low lead-bismuth corrosion, strong oxidation resistance and high density, strong process stability, and can be mass-produced.

[0059] Using the lead-bismuth resistant coating provided by the present invention, the bonding strength, lead-bismuth corrosion weight loss rate and anti-oxidation weight gain of Example 2 are the best, wherein the bonding strength reaches 70Mpa, the lead-bismuth corrosion weight loss rate reaches 0.28mg / cm², the anti-oxidation weight gain reaches 0.13mg / cm², and the porosity reaches 0.8%. Figure 7 As shown, when Example 2 is tested by DSC, there is no extra peak, indicating strong oxidation resistance, thereby verifying strong process stability. Therefore, the material strength is significantly improved, and it has the characteristics of long-term stability. It can be seen that the introduced material needs to be within a certain amount, and adding too much or too little will affect the performance. Therefore, considering the comprehensive performance influence of the lead-bismuth resistant coating, the lead-bismuth resistant coating prepared by the present invention significantly enhances the bonding strength, corrosion resistance and oxidation resistance of the material under the condition that the preparation process maintains stability.

[0060] In summary, the embodiment of the present application constructs a high-performance lead-bismuth resistant coating through the interface synergistic effect of the functional transition layer, the stress regulation effect of the composition gradient of the metal bonding layer, and the interface strengthening effect of the in-situ reaction of the corrosion-resistant layer: the functional transition layer adopts a TiAlN / CrZrN nano-multilayer superlattice structure, and realizes interface matching and stress buffering through high interface density and dislocation interaction, which significantly improves the coating bonding strength. At the same time, through the dual mechanism of physical barrier to the penetration of corrosive media and chemical adsorption of active ions by nitrogen vacancies in the CrZrN layer, the lead-bismuth corrosion weight loss rate is reduced to 0.25-0.28 mg / cm²; the composition gradient transition structure of the metal bonding layer gradually matches the thermal expansion coefficient of the substrate and the coating, reducing the interface elements. The element mutation and residual stress increase the bonding strength to 68-70MPa, optimize the internal stress distribution of the coating, reduce the diffusion path of the corrosive medium and oxygen, and further improve the corrosion resistance and oxidation resistance; the Ta-Zr-OC nano-interface phase in situ generated by the Y2O3-ZrO2-CeO2 eutectic oxide in the corrosion-resistant layer fills the pores, refines the grains and enhances the interlayer bonding, forming a dense antioxidant barrier and inhibiting crack propagation, making the corrosion weight loss rate and antioxidant weight gain as low as 0.25-0.28mg / cm² and 0.11-0.13mg / cm² respectively, synergistically constructing a gradient protection system of "strong bonding-impedance-corrosion resistance", which significantly improves the comprehensive performance of the coating in a lead-bismuth environment.

[0061] According to a lead-bismuth-resistant coating and a preparation method thereof proposed in the embodiment of the present application, a three-level synergistic protective coating system is constructed, wherein the gradient metal bonding layer adopts a high / medium entropy alloy composite structure, utilizes the multi-principal element lattice distortion effect to enhance the interface bonding (bonding strength is increased by >40%), and realizes a smooth transition of the thermal expansion coefficient through the composition gradient design, effectively solving the thermal stress failure problem of the traditional coating; the nano multilayer functional transition layer adopts a TiAlN / CrZrN superlattice structure, and its high-density interface produces a significant dislocation interaction strengthening effect, which cooperates with CrZr The controllable nitrogen vacancies in the N layer chemically adsorb Pb-Bi active ions, constructing a double diffusion barrier to reduce the permeability of the corrosive medium by 2 orders of magnitude; the ceramic corrosion-resistant layer regulates the stability of the ZrO2 tetragonal phase by rare earth doping, and combines the in-situ generated Ta-Zr-OC nano-interface phase to produce a grain boundary pinning effect, which refines the oxide grains to the nanoscale, and reduces the oxidation rate by 75% compared with traditional coatings; the integrated plasma spraying-magnetron sputtering-laser remelting composite process achieves precise control of the metal layer porosity <1% and the ceramic layer density >99.5%. This system breaks through the technical bottlenecks of insufficient bonding strength of traditional coatings, single corrosion resistance mechanism, and poor process stability, and increases the service life of lead-bismuth environments by more than 3 times.

[0062] Although the embodiments of the present application have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the appended claims and their equivalents.

[0063] The above describes the present application and its implementation methods, which are not restrictive and the actual application is not limited thereto. In short, if ordinary technicians in the field are inspired by it and design structural methods and embodiments similar to the technical solution without creative design without departing from the purpose of the present application, they should all fall within the scope of protection of the present application.

Claims

1. A lead-resistant bismuth coating, characterized in that: The coating consists of a metal bonding layer, a functional transition layer and a corrosion resistant layer, wherein: The metal bonding layer is composed of a high entropy alloy and a medium entropy alloy to form a composition gradient transition structure, the high entropy alloy is a nearly equiatomic alloy of Fe, Co, Ni, Cr, and Al, and the Al content is 5-10at.%, and the medium entropy alloy is a quaternary alloy of FeCoNiCr; The functional transition layer is a transition metal nitride layer; The corrosion-resistant layer is a eutectic composite layer of rare earth oxide and stabilized oxide.

2. The lead-resistant bismuth coating according to claim 1, characterized in that: The volume ratio of the high entropy alloy to the medium entropy alloy is (3:1)-(1:1), the high entropy alloy component is FeCoNiCrAl, and the medium entropy alloy component is FeCoNiCr.

3. The lead-resistant bismuth coating according to claim 1, characterized in that: The transition metal nitride layer is a nano multilayer superlattice structure formed by alternately depositing TiAlN and CrZrN, wherein the single layer thickness of the nano multilayer superlattice structure is 10-50nm, and the total thickness is 80-150nm.

4. The lead-resistant bismuth coating according to claim 3, characterized in that: The thickness ratio of the TiAlN layer to the CrZrN layer is (1:2)-(2:1), and the nitrogen vacancy concentration in the CrZrN layer is 5-15%.

5. The lead-resistant bismuth coating according to claim 1, characterized in that: The rare earth oxide is Y2O3, and the stabilized oxides are ZrO2 and CeO2, wherein the molar ratio of Y2O3 to CeO2 is 1:(0.2-0.8), and ZrO2 exists in a tetragonal stabilized form.

6. The lead-resistant bismuth coating according to claim 1, characterized in that: The Y2O3-ZrO2-CeO2 eutectic oxide in the corrosion-resistant layer generates a Ta-Zr-OC interface phase through an in-situ reaction. The Ta-Zr-OC interface phase is distributed between layers in the form of nanoparticles with a particle size of 20-100 nm.

7. A method for preparing the lead-resistant bismuth coating according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step 1: depositing a metal bonding layer on the surface of the substrate by a plasma spraying-physical vapor deposition composite process, wherein the plasma spraying power is 30-50 kW, the spraying distance is 80-120 mm, and the substrate preheating temperature is ≤400°C; Step 2: depositing a TiAlN / CrZrN superlattice functional transition layer on the metal bonding layer by high-power pulsed magnetron sputtering technology, wherein the pulse frequency is 500-1000 Hz and the duty cycle is 1-3%; Step three: Use laser-assisted chemical vapor deposition to form a corrosion-resistant layer on the surface of the functional transition layer, wherein the laser power is 200-500W, the deposition temperature is 600-800°C, and the precursor is a mixed solution of Y(C5H7O2)3, ZrCl4 and Ce(NO3)3.

8. The method for preparing the lead-resistant bismuth coating according to claim 7, characterized in that: Argon gas is introduced during the physical vapor deposition process, wherein the pressure is 0.5-2Pa and the bias voltage is -50 to -150V.

9. The method for preparing the lead-resistant bismuth coating according to claim 8, characterized in that: The high entropy alloy and the medium entropy alloy in the metal bonding layer are sprayed alternately to achieve a gradient transition of composition, and each layer is subjected to laser nitriding treatment after spraying, the laser scanning rate is 2-5 mm / s, and the depth of the nitriding layer is 5-20 μm.

10. The method for preparing the lead-resistant bismuth coating according to claim 9, characterized in that: The corrosion-resistant layer is subjected to amorphous laser remelting treatment, and the laser power density is 5×10 2 -8×10³W / cm², scanning speed is 10-50mm / s, forming a nanocrystalline-amorphous composite structure with a surface porosity of <0.5%.

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