Multicomponent alloy anti-oxidation coating based on interface nanocrystalline structure and preparation method of multicomponent alloy anti-oxidation coating
By preparing a multi-element alloy anti-oxidation coating with an inner layer of Al2O3 and an outer layer of MoSi2, ZrC, and MnB on the surface of a molybdenum alloy substrate, the problems of easy cracking and insufficient anti-oxidation performance of molybdenum alloy at high temperatures were solved, and the coating was tightly bonded to the substrate and the anti-oxidation performance at high temperatures was improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-02-03
- Publication Date
- 2026-03-31
AI Technical Summary
Molybdenum alloys are prone to cracking at high temperatures and have insufficient oxidation resistance. The existing coatings have a large difference in thermal expansion coefficients with the substrate, which makes the coatings prone to cracking.
An Al2O3 inner layer was prepared on the surface of a molybdenum alloy substrate by magnetron sputtering and then annealed to form an α-Al2O3 nanocrystalline inner layer. An outer layer was then coated with a slurry, consisting of MoSi2, ZrC, MnB and sintering aids. The outer layer was then sintered to form a multi-element alloy anti-oxidation coating.
It significantly improves the coating's oxidation resistance and crack resistance, extends the service life and stability of molybdenum alloys in high-temperature environments, ensures a tight bond between the coating and the substrate, mitigates differences in thermal expansion coefficients, and forms a dense oxide layer to block oxygen penetration.
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Figure CN121759952A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of metal coating preparation technology, specifically a multi-element alloy anti-oxidation coating based on interface nanocrystalline structure and its preparation method. Background Technology
[0002] Molybdenum alloys possess excellent properties such as high melting point, high creep resistance, high thermal conductivity, and low coefficient of thermal expansion. However, they also suffer from low-temperature brittleness, low room-temperature recrystallization temperature, and poor high-temperature oxidation resistance, which limit their long-term service life. Common methods for addressing this issue include alloying and coating. While alloying is difficult to achieve due to limitations imposed on the substrate, coatings are more frequently used. However, existing coatings are prone to cracking due to the significant difference in thermal expansion coefficients between the coating and the substrate. Summary of the Invention
[0003] To address the problems existing in the prior art, the main objective of this invention is to propose a multi-element alloy anti-oxidation coating based on an interface nanocrystalline structure and its preparation method. The coating obtained by this invention has both excellent anti-oxidation and anti-cracking properties, significantly improving the service life and stability of molybdenum alloys under high-temperature environments.
[0004] To solve the above-mentioned technical problems, the present invention provides the following technical solution: A method for preparing a multi-element alloy anti-oxidation coating based on an interface nanocrystalline structure includes the following steps: An Al2O3 inner layer was prepared on the surface of a molybdenum alloy substrate by magnetron sputtering to obtain the first composite preform. The first composite preform is annealed to obtain α-Al2O3 nanocrystals as the inner layer of the coating, thus obtaining the second composite preform; A slurry coating is applied to the second composite preform, and the slurry coating is dried to form an outer preform on the surface of the first composite preform, resulting in a dried preform. The outer preform comprises mixed powder and sintering aids. The mixed powder comprises MoSi2 powder, ZrC powder, and MnB powder. By mass percentage, the components of the mixed powder are: 59%-61%, ZrC: 19%-21%, MnB: 19%-21%, and the mass ratio of sintering aids to the total mass of mixed powder is 1:(9-11). The dried blank is sintered in a protective atmosphere at 1190-1210℃ for 55-65 minutes to obtain the multi-element alloy anti-oxidation coating based on the interface nanocrystalline structure.
[0005] Preferably, an Al2O3 inner layer is prepared on the surface of a molybdenum alloy substrate by magnetron sputtering using an Al target.
[0006] Preferably, the thickness of the Al2O3 inner layer is 1-5 μm, and the combined thickness of the Al2O3 inner layer and the outer layer of the preform is controlled between 30-70 μm.
[0007] Preferably, when the first composite preform is annealed to obtain α-Al2O3 nanocrystals as the inner layer of the coating, and the second composite preform is obtained, the annealing atmosphere is an inert atmosphere, the heating rate is 4-6℃ / min, the annealing temperature is 500-800℃, and the holding time is 1-3h.
[0008] Preferably, before preparing the Al2O3 inner layer on the surface of the molybdenum alloy substrate by magnetron sputtering, the surface of the molybdenum alloy substrate is polished smooth and the oxide layer is removed, followed by cleaning and drying, and then the Al2O3 inner layer is prepared on the surface of the molybdenum alloy substrate by magnetron sputtering.
[0009] Preferably, the preparation process of the slurry for forming a slurry coating on the second composite preform includes: Anhydrous ethanol is added to the components of the outer layer green body, and the mixture is ball-milled at a speed of 290-310 rpm for 11.5-12.5 h to obtain the slurry, wherein the mass ratio of the components of the outer layer green body to anhydrous ethanol is (4-6):1.
[0010] Preferably, after applying the slurry coating to the second composite preform, it is dried at 25-35°C for 5.5-6.5 hours to allow the slurry coating to dry.
[0011] Preferably, the sintering aid is polyvinyl butyral.
[0012] Preferably, a slurry coating is applied to the second composite preform using a spray coating process.
[0013] The present invention also provides a multi-element alloy anti-oxidation coating based on an interface nanocrystalline structure, wherein the multi-element alloy anti-oxidation coating based on an interface nanocrystalline structure is prepared by the preparation method of the present invention as described above.
[0014] The present invention has the following beneficial effects: This invention relates to a method for preparing a multi-element alloy anti-oxidation coating based on an interface nanocrystalline structure. It specifically addresses the problems of existing molybdenum alloy coatings exhibiting large differences in thermal expansion coefficients between the coating and the substrate, susceptibility to cracking, and insufficient high-temperature oxidation resistance. By rationally designing the coating preparation process and component ratios, it achieves a synergistic improvement in coating performance and process practicality. Specifically, this invention uses magnetron sputtering to prepare an Al2O3 inner layer on the surface of a molybdenum alloy substrate, followed by annealing to obtain an α-Al2O3 nanocrystalline inner layer. The thermal expansion coefficient of α-Al2O3 nanocrystals is between that of the molybdenum alloy substrate and the outer coating, effectively buffering the difference in thermal expansion between the two and reducing thermal stress caused by temperature changes. Simultaneously, the magnetron sputtering process enables the inner layer to form a tight mechanical bond with the substrate, reducing thermal stress concentration and fundamentally inhibiting oxidation. To prevent coating cracking, the outer layer preform is formulated with MoSi2, ZrC, MnB, and sintering aids in specific mass percentages. MoSi2 forms a dense oxide protective layer at high temperatures to block oxygen penetration. ZrC and MnB work synergistically, and the products of the reaction between Zr and B elements at high temperatures and oxygen can fill the coating pores, reduce oxygen penetration channels, and inhibit microcracks caused by volume changes during high-temperature oxidation of the coating, thus achieving a dual improvement in oxidation resistance and crack resistance. The outer layer preform is prepared by slurry coating, which is not limited by the size of the substrate. Furthermore, the sintering process at 1190-1210℃ for 55-65 minutes in a protective atmosphere ensures that the outer layer components are fully combined to form a uniform and dense coating, while avoiding excessive sintering that could damage the bonding strength between the inner layer and the substrate. Attached Figure Description
[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.
[0016] Figure 1 This is a SEM image of the cross-section of the multi-element alloy anti-oxidation coating based on the interface nanocrystalline structure obtained in Example 1 of the present invention. Figure 2 This is a SEM image of the cross-section of the multi-element alloy anti-oxidation coating based on the interface nanocrystalline structure obtained in Example 2 of the present invention; Figure 3 The two-step XRD patterns of the coating prepared by the two-step preparation method in Example 1 of the present invention are shown, wherein (a) is after annealing of the single inner layer; and (b) is the double coating. Figure 4 This is a SEM image of the cross-section of the multi-element alloy anti-oxidation coating based on the interface nanocrystalline structure obtained in Example 3 of the present invention; Figure 5This is a SEM image of the cross-section of the multi-element alloy anti-oxidation coating based on the interface nanocrystalline structure obtained in Example 4 of the present invention. Figure 6 This is a SEM image of the cross-section of the multi-element alloy anti-oxidation coating based on the interface nanocrystalline structure obtained in Example 5 of the present invention; Figure 7 This is a SEM image of the coating surface obtained in Comparative Example 1 of the present invention. Figure 8 This is a SEM image of the cross-section of the coating obtained in Comparative Example 1 of the present invention. Figure 9 The image shows the weight loss curves of the coatings obtained in the comparative examples and embodiments. Detailed Implementation
[0017] The technical solutions described below in conjunction with the embodiments will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0018] To achieve a high-strength metallurgical bond between the coating and the substrate and to construct an effective oxygen diffusion barrier layer, this invention employs a combined magnetron sputtering and heat treatment technique to generate a nanoscale α-Al₂O₃ structure in situ at the interface. This nanocrystalline intermediate layer not only strengthens the interfacial bonding but also effectively blocks the inward diffusion of oxygen. Based on this, a Si-Zr-Mn-BC multi-element coating system is constructed externally using a slurry spraying process, enabling it to form a continuous and dense SiO₂ oxide layer during high-temperature service. The composite coating system prepared by this invention exhibits excellent oxidation resistance and crack resistance, significantly improving the service life and stability of molybdenum alloys under high-temperature conditions.
[0019] Specifically, the present invention provides a method for preparing a multi-element alloy anti-oxidation coating based on an interfacial nanocrystalline structure, comprising the following steps: Step 1: After polishing the surface of the molybdenum alloy substrate with sandpaper, clean the impurities on the surface with anhydrous ethanol, and then dry it to obtain the treated molybdenum alloy substrate.
[0020] Step 2: Using an Al target, an Al2O3 inner layer is sputtered onto the surface of the molybdenum alloy substrate treated in Step 1 to obtain a first composite preform; wherein the thickness of the Al2O3 inner layer is 1-5 μm. Preferably, the aluminum target is a high-purity Al target with a purity of 99.999% or higher. In the following embodiments and comparative examples of this invention, the purity of the Al target is 99.999%.
[0021] Step 3: Place the first composite preform in a drying oven to dry for later use. Then, anneal the first composite preform using a muffle furnace or tube furnace to obtain the second composite preform. During annealing, the process is carried out in an inert atmosphere (such as argon) and heated to 500-800℃ at a rate of 5±1℃ / min, and held for 1-3 hours to obtain α-Al2O3 nanocrystals as the inner layer of the entire composite coating.
[0022] Step 4: Mix MoSi2 powder, ZrC powder, MnB powder, and sintering aid in a certain proportion to obtain a mixture. By mass percentage, the mixture comprises: 59%-61% MoSi2 powder, 19%-21% ZrC, and 19%-21% MnB. The mass ratio of the sintering aid to the total mixed powder is 1:(9-11). Then, add anhydrous ethanol to the mixture and perform wet ball milling to prepare a uniform slurry. The ball milling speed is 300±10 rpm, and the milling time is 11.5-12.5 h. During ball milling, the mill can rotate forward for a period and then reverse, with each rotation lasting half the time. The mass ratio of the mixture to anhydrous ethanol is (4-6):1. The sintering aid can be PVB (polyvinyl butyral).
[0023] Step 5: Using a spray coating process, a slurry coating of uniform thickness is applied to the surface of the second composite preform and dried at 30±5℃ for 5.5-6.5h to dry the slurry coating and obtain a dried preform; wherein, the total thickness of the coating is controlled to be 30-70μm.
[0024] Step 6: Place the dried blank into a pre-fired crucible and sinter it in a tube furnace at 1200±10℃ for 55-65 min to obtain the multi-element alloy anti-oxidation coating based on the interface nanocrystalline structure on the surface of the molybdenum alloy substrate; wherein, sintering is carried out in an argon atmosphere.
[0025] In the above-mentioned solution of the present invention, the data before “±” is the set value of the corresponding parameter, and the data after “±” is the deviation value of the corresponding parameter (mainly caused by fluctuations in the equipment control process). It can be understood that the technical solution of the present invention is feasible within the parameter range determined by the set value and the deviation value.
[0026] This invention proposes a composite protective system consisting of a "magnetron sputtered α-Al₂O₃ inner layer + slurry-sintered Si-Zr-B multi-component silicide outer layer." Its core advantages and synergistic mechanisms are as follows: The outer layer, by introducing Zr and B elements, generates a composite product of borate and zirconium-based oxides at high temperatures, achieving self-healing of cracks. The slurry sintering process is adaptable to substrates of any size / shape, with low equipment cost and easy industrialization. The inner α-Al₂O₃ layer alleviates the mismatch in thermal expansion coefficients and forms a strong mechanical bond with the substrate. During sintering, it reacts with the outer Si element to generate an Al₂SiO₅ mullite transition phase, achieving chemical bonding and structural bridging between the inner and outer layers. Zr and B elements further optimize the interfacial phase properties through interfacial segregation. Through the synergistic effect of "inner layer stress buffering - strong interfacial bonding - outer layer self-healing," the overall bonding strength, thermal shock resistance, and high-temperature oxidation resistance of the coating are significantly improved.
[0027] The multi-element alloy anti-oxidation coating based on the interface nanocrystalline structure prepared by this invention is a double-layer coating. Through the synergistic design of the "nanocrystalline interface layer" and the "multi-element outer coating", a double anti-oxidation barrier is constructed while achieving a strong and tough bond between the coatings, thereby significantly improving the long-term service performance of molybdenum alloys at high temperatures.
[0028] The technical solution of the present invention will be further described below with reference to specific embodiments.
[0029] Example 1 This embodiment describes a method for preparing a multi-element alloy anti-oxidation coating based on an interfacial nanocrystalline structure, including the following steps: S1. After polishing the surface of the molybdenum alloy substrate with sandpaper, the impurities on the surface are cleaned with anhydrous ethanol, and then dried to obtain the treated molybdenum alloy substrate. S2, using an Al target, an Al2O3 inner layer is sputtered onto the surface of the molybdenum alloy substrate treated in S1 to obtain the first composite preform; wherein, the thickness of the Al2O3 inner layer is 5μm.
[0030] The first composite preform was placed in a drying oven for later use. It was then annealed in a muffle furnace to obtain the second composite preform. During annealing, the first composite preform was placed in a corundum crucible, and then placed in a muffle furnace. The muffle furnace used a thermocouple as a heat source, and the heating temperature and time were controlled for annealing. The heating temperature was 500℃, the heating time was 1 hour, and the annealing atmosphere was argon. This yielded α-Al₂O₃ nanocrystals as the inner layer of the entire composite coating.
[0031] S3, Prepare the outer layer of the composite coating; MoSi2 powder, ZrC powder, MnB powder, and sintering aid were mixed in a certain proportion to obtain a mixture, which, by mass percentage, included MoSi2: 60%, ZrC: 20%, and MnB: 20%, with the sintering aid PVB having a mass ratio of 1:10 to the total mass of the mixed powder. Anhydrous ethanol was then added to the mixed powder, and the mixture was wet-milled using a QM-1SP planetary high-energy ball mill at 300 rpm for 12 hours to prepare a uniform slurry. During ball milling, the forward and reverse rotation times were equal, and the mass ratio of the mixed powder to anhydrous ethanol was 5:1. A uniform slurry coating (thickness controlled at 50 μm) was applied to the pretreated substrate using a spray coating process, and then dried at 30°C for 6 hours. The dried blank was then placed in a pre-fired crucible and sintered in a vacuum sintering furnace at 1200°C for 1 hour using argon as the sintering medium to prepare a complete coated sample.
[0032] like Figure 1 As shown, the multi-element alloy anti-oxidation coating based on an interface nanocrystalline structure prepared in this embodiment has a clearly defined, smooth, and continuous interface between the upper coating and the lower substrate, without obvious cracks. Figure 3 As shown, (a) the spectrum shows obvious Al2O3 characteristic peaks, and α-Al2O3 characteristic peaks were also detected, indicating that the inner layer prepared by magnetron sputtering successfully synthesized the thermally stable α-Al2O3 phase after annealing. (b) In addition to the Al2O3 and α-Al2O3 peaks of the inner layer, phases such as SiO2, ZrO2, and MoO2 also appeared in the figure, corresponding to the oxidation products of the outer silicide. This indicates that the double-layer coating structure is complete, and the α-Al2O3 of the inner layer remains stable during the sintering process of preparing the outer layer. Figure 9 As shown, the composite coating in this embodiment exhibits a weight loss of 0.2183 g / cm³ at 1100°C. 2 The weight loss at 1200℃ was 0.4926 g / cm³. 2 At 1300℃, the weight loss is only about 0.9485 g / cm³. 2 (<1.0 g / cm) 2 ).
[0033] Example 2 This embodiment describes a method for preparing a multi-element alloy anti-oxidation coating based on an interfacial nanocrystalline structure, including the following steps: S1. After polishing the surface of the molybdenum alloy substrate with sandpaper, the surface impurities are cleaned with anhydrous ethanol, and then dried to obtain the treated molybdenum alloy substrate.
[0034] S2, using an Al target, an Al2O3 inner layer is sputtered onto the surface of the molybdenum alloy substrate treated in S1 to obtain the first composite preform; wherein, the thickness of the Al2O3 inner layer is 5μm.
[0035] The first composite preform was placed in a drying oven for later use. It was then annealed in a muffle furnace to obtain the second composite preform. During annealing, the first composite preform was placed in a corundum crucible, and then placed in a muffle furnace. The muffle furnace used a thermocouple as a heat source, and the heating temperature and time were controlled for annealing. The heating temperature was 600℃, the heating time was 2 hours, and the annealing atmosphere was argon. This yielded α-Al₂O₃ nanocrystals as the inner layer of the entire composite coating.
[0036] S3, Prepare the outer layer of the composite coating; MoSi2 powder, ZrC powder, MnB powder, and sintering aid powder are mixed in a certain proportion to obtain a mixture. By mass percentage, the mixed powder consists of 60% MoSi2 powder, 20% ZrC powder, and 20% MnB powder, and the mass ratio of sintering aid PVB to the total mixed powder is 1:10. Then, anhydrous ethanol was added to the mixed powder, and wet ball milling was performed using a QM-1SP planetary high-energy ball mill at a speed of 300 rpm for 12 hours to prepare a uniform slurry. During ball milling, the forward and reverse rotation times were equal, and the mass ratio of the mixed powder to anhydrous ethanol was 5:1. A uniform slurry coating (thickness controlled at 50 μm) was applied to the pretreated substrate using a spray coating process, and then dried at 30°C for 6 hours. The dried blank was then placed in a pre-fired crucible and sintered in a vacuum sintering furnace at a temperature of 1200°C for 1 hour using argon as the sintering medium to prepare a complete coated sample.
[0037] like Figure 2 As shown, the upper coating of the multi-element alloy anti-oxidation coating based on the interface nanocrystalline structure prepared in this embodiment exhibits a continuous and dense fibrous stacked structure without obvious pores or through cracks. The interface between the coating and the underlying substrate is clear and tightly bonded, without any signs of delamination or cracking. Figure 9 As shown, the composite coating obtained in Example 2 lost 0.2485 g / cm³ at 1100°C. 2 The weight loss at 1200 ℃ was 0.5889 g / cm³. 2 The weight loss at 1300℃ was 0.8762 g / cm³. 2 .
[0038] Example 3 This embodiment describes a method for preparing a multi-element alloy anti-oxidation coating based on an interfacial nanocrystalline structure, including the following steps: S1. After polishing the surface of the molybdenum alloy substrate with sandpaper, the surface impurities are cleaned with anhydrous ethanol, and then dried to obtain the treated molybdenum alloy substrate.
[0039] S2, using an Al target, an Al2O3 inner layer is sputtered onto the surface of the molybdenum alloy substrate treated in S1 to obtain the first composite preform; wherein, the thickness of the Al2O3 inner layer is 5μm.
[0040] The first composite preform was placed in a drying oven for later use. It was then annealed in a muffle furnace to obtain the second composite preform. During annealing, the first composite preform was placed in a corundum crucible, and then placed in a muffle furnace. The muffle furnace used a thermocouple as a heat source, and the heating temperature and time were controlled for annealing. The heating temperature was 800℃, the heating time was 1 hour, and the annealing atmosphere was argon. This yielded α-Al₂O₃ nanocrystals as the inner layer of the entire composite coating.
[0041] S3, Prepare the outer layer of the composite coating; MoSi2 powder, ZrC powder, MnB powder, and sintering aid powder are mixed in a certain proportion to obtain a mixture. By mass percentage, the mixed powder consists of 60% MoSi2 powder, 20% ZrC powder, and 20% MnB powder, and the mass ratio of sintering aid PVB to the total mixed powder is 1:9. Then, anhydrous ethanol was added to the mixed powder, and wet ball milling was performed using a QM-1SP planetary high-energy ball mill at a speed of 300 rpm for 12 hours to prepare a uniform slurry. During ball milling, the forward and reverse rotation times were equal, and the mass ratio of the mixed powder to anhydrous ethanol was 6:1. A uniform slurry coating (thickness controlled at 50 μm) was applied to the pretreated substrate using a spray coating process, and then dried at 30°C for 6 hours. The dried blank was then placed in a pre-fired crucible and sintered in a vacuum sintering furnace at a temperature of 1200°C for 1 hour using argon as the sintering medium to prepare a complete coated sample.
[0042] like Figure 4 As shown, the multi-element alloy anti-oxidation coating based on the interface nanocrystalline structure prepared in this embodiment has a continuous and dense surface morphology, with only a few scattered micro-pits and no large-area cracks. Figure 9 As shown, the composite coating prepared in Example 3 lost 0.1975 g / cm³ at 1100°C. 2 At 1200℃, it is 0.4183 g / cm³. 2 At 1300℃, it is 0.9183 g / cm³. 2 .
[0043] Example 4 This embodiment describes a method for preparing a multi-element alloy anti-oxidation coating based on an interfacial nanocrystalline structure, including the following steps: S1. After polishing the surface of the molybdenum alloy substrate with sandpaper, the surface impurities are cleaned with anhydrous ethanol, and then dried to obtain the treated molybdenum alloy substrate.
[0044] S2, using an Al target, an Al2O3 inner layer is sputtered onto the surface of the molybdenum alloy substrate treated in S1 to obtain the first composite preform; wherein, the thickness of the Al2O3 inner layer is 1 μm.
[0045] The first composite preform was placed in a drying oven for later use. It was then annealed in a muffle furnace to obtain the second composite preform. During annealing, the first composite preform was placed in a corundum crucible, and then placed in a muffle furnace. The muffle furnace used a thermocouple as a heat source, and the heating temperature and time were controlled for annealing. The heating temperature was 700℃, the heating time was 2 hours, and the annealing atmosphere was argon. This yielded α-Al₂O₃ nanocrystals as the inner layer of the entire composite coating.
[0046] S3, Prepare the outer layer of the composite coating; MoSi2 powder, ZrC powder, MnB powder, and sintering aid powder are mixed in a certain proportion to obtain a mixture. By mass percentage, the mixed powder composed of MoSi2 powder, ZrC powder, and MnB powder comprises 60% MoSi2 powder, 20% ZrC powder, and 20% MnB powder, and the mass ratio of sintering aid PVB to the total mixed powder is 1:11. Then, anhydrous ethanol was added to the mixed powder, and wet ball milling was performed using a QM-1SP planetary high-energy ball mill at a speed of 300 rpm for 12 hours to prepare a uniform slurry. During ball milling, the forward and reverse rotation times were equal, and the mass ratio of the mixed powder to anhydrous ethanol was 4:1. A uniform slurry coating (thickness controlled at 50 μm) was applied to the pretreated substrate using a spray coating process, and then dried at 30°C for 6 hours. The dried blank was then placed in a pre-fired crucible and sintered in a vacuum sintering furnace at a temperature of 1200°C for 1 hour using argon as the sintering medium to prepare a complete coated sample.
[0047] like Figure 5 As shown, the multi-element alloy anti-oxidation coating based on the interface nanocrystalline structure prepared in this embodiment exhibits a uniform and dense microstructure, with no obvious through-pores, microcracks, or delamination defects within the layer, and the particles are tightly stacked. The interface between the coating and the substrate is clear and continuously bonded, without any signs of debonding or cracking. Figure 9 The weight loss curve shown corresponds to an oxidation weight loss of 0.2781 g / cm³ for the composite coating at 1100℃. 2The weight loss due to oxidation at 1200℃ was 0.5591 g / cm³. 2 At 1300℃, it is 0.9841 g / cm³. 2 .
[0048] Example 5 This embodiment describes a method for preparing a multi-element alloy anti-oxidation coating based on an interfacial nanocrystalline structure, including the following steps: S1. After polishing the surface of the molybdenum alloy substrate with sandpaper, the impurities on the surface are cleaned with anhydrous ethanol, and then dried to obtain the treated molybdenum alloy substrate. S2, using an Al target, an Al2O3 inner layer is sputtered onto the surface of the molybdenum alloy substrate treated in S1 to prepare the first composite preform; wherein, the thickness of the Al2O3 inner layer is 3μm; The first composite preform was placed in a drying oven for later use. It was then annealed in a muffle furnace to obtain the second composite preform. During annealing, the first composite preform was placed in a corundum crucible, and then placed in a muffle furnace. The muffle furnace used a thermocouple as a heat source, and the heating temperature and time were controlled for annealing. The heating temperature was 600℃, the heating time was 2 hours, and the annealing atmosphere was argon. This yielded α-Al₂O₃ nanocrystals as the inner layer of the entire composite coating.
[0049] S3, Prepare the outer layer of the composite coating; MoSi2 powder, ZrC powder, MnB powder, and sintering aid powder are mixed in a certain proportion to obtain a mixture. By mass percentage, the mixed powder consists of 60% MoSi2 powder, 20% ZrC powder, and 20% MnB powder, and the mass ratio of sintering aid PVB to the total mixed powder is 1:10. Then, anhydrous ethanol was added to the mixed powder, and wet ball milling was performed using a QM-1SP planetary high-energy ball mill at a speed of 300 rpm for 12 hours to prepare a uniform slurry. During ball milling, the forward and reverse rotation times were equal, and the mass ratio of the mixed powder to anhydrous ethanol was 5:1. A uniform slurry coating (thickness controlled at 50 μm) was applied to the pretreated substrate using a spray coating process, and then dried at 30°C for 6 hours. The dried blank was then placed in a pre-fired crucible and sintered in a vacuum sintering furnace at a temperature of 1200°C for 1 hour using argon as the sintering medium to prepare a complete coated sample.
[0050] like Figure 6 As shown, the multi-element alloy anti-oxidation coating based on the interface nanocrystalline structure prepared in this embodiment has a uniform and dense microstructure, with no macroscopic cracks and only a very small number of dispersed micro-defects; the coating and the molybdenum substrate have a tight interface bond with each other, with no obvious debonding or delamination. Figure 9The high-temperature oxidation weight loss curves quantitatively characterized the oxidation kinetics of different coatings in the 1100–1300℃ range. The composite coating corresponding to Example 5 showed oxidation weight losses of 0.2375 g / cm³ at 1100℃, 1200℃, and 1300℃. 2 0.6078 g / cm 2 and 0.9501 g / cm 2 . Comparative Example 1 The difference between this comparative example and Example 1 is that step S2 in Example 1 is omitted.
[0051] The SEM image of the coating surface in this comparative example is shown below. Figure 8 As shown, obvious surface microcracks are visible on the coating surface. See also Figure 9 At 1100℃, the oxidative weight loss was 0.3037 g / cm³. 2 At 1200℃, the weight loss rapidly increased to approximately 1.0298 g / cm³. 2 At 1300℃, the weight loss further increased to 1.3165 g / cm³. 2 (>1.0 g / cm) 2 ).
[0052] Comparative Example 2 The difference between this comparative example and Example 2 is that the powder in the outer layer of Example 2 does not contain MoSi2 elements in step S3.
[0053] The SEM image of the coating section in this comparative example is shown below. Figure 8 As shown, the coating does not bond tightly to the substrate, resulting in obvious delamination. See also Figure 9 At 1100℃, the oxidative weight loss was 0.3149 g / cm³. 2 At 1200℃, the weight loss rapidly increased to 1.0565 g / cm³. 2 At 1300℃, the weight loss further increased to 1.3592 g / cm³. 2 (>1.0 g / cm) 2 ).
[0054] The microstructure characterization of the coatings prepared in this invention shows that the multi-element alloy anti-oxidation coating based on the interface nanocrystalline structure prepared in the embodiments of this invention maintains a continuous and dense microstructure after oxidation, without obvious cracking or peeling, and is firmly bonded to the substrate interface without delamination or debonding. In contrast, the comparative coatings showed significant crack defects or poor interface bonding before oxidation, which provided diffusion channels for rapid oxygen atom penetration. Further high-temperature oxidation weight loss tests showed that after 1 hour of oxidation in air at 1100℃, 1200℃, and 1300℃, the mass loss of the coatings in the embodiments ranged from 0.2–1.0 g / cm³. 2 The comparative coating, however, exhibited significantly higher oxidative weight loss under the same conditions, especially exceeding 1.0 g / cm³ at 1300 °C. 2 The aforementioned performance differences are highly correlated with microstructural characteristics: the dense structure and strong interfacial bonding of the coating in the example can effectively block oxygen diffusion, thereby inhibiting substrate oxidation and volatilization; while the initial defects of the coating in the comparative example accelerate oxygen penetration and substrate oxidation, ultimately leading to a significant deterioration in protective performance.
[0055] As can be seen from the above embodiments and comparative examples, the present invention proposes a composite protection system of "magnetron sputtering α-Al2O3 inner layer + slurry sintered Si-Zr-B multi-component silicide outer layer". Its core advantages and synergistic mechanisms are as follows: The outer layer, by introducing Zr and B elements, generates a composite product of borate and zirconium-based oxides at high temperatures, achieving self-healing of cracks; the slurry sintering process is adaptable to substrates of any size / shape, with low equipment cost and easy industrialization. The inner α-Al2O3 layer not only alleviates the mismatch in thermal expansion coefficients but also forms a strong mechanical bond with the substrate. During sintering, it reacts with the outer Si element to generate an Al2SiO5 mullite transition phase, achieving chemical bonding and structural bridging between the inner and outer layers. The Zr and B elements further optimize the interfacial phase performance through interfacial segregation. Through the synergistic effect of "inner layer stress buffering - strong interfacial bonding - outer layer self-healing", the overall bonding strength, thermal shock resistance, and high-temperature oxidation resistance of the coating are significantly improved.
[0056] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.
Claims
1. A method for preparing an oxidation-resistant coating based on a multi-component alloy nanocrystalline structure, characterized in that, The method comprises the following steps: An Al2O3 inner layer is prepared on the surface of the molybdenum alloy base by a magnetron sputtering method to obtain a first composite blank; The first composite blank is annealed to obtain α-Al2O3 nanocrystals as an inner layer of the coating to obtain a second composite blank; A slurry coating is coated on the second composite blank, and the slurry coating is dried to form an outer layer blank on the surface of the first composite blank, and then a dried blank is obtained; the outer layer blank comprises mixed powder and a sintering aid, the mixed powder comprises MoSi2 powder, ZrC powder and MnB powder, and the mixed powder comprises MoSi2: 59%-61%, ZrC: 19%-21% and MnB: 19%-21% by mass percentage, and the mass ratio of the sintering aid to the total mass of the mixed powder is 1: (9-11); The dried blank is sintered at 1190-1210 ℃ for 55-65 min in a protective atmosphere to obtain the multi-element alloy oxidation-resistant coating based on the interface nanocrystalline structure.
2. The method of claim 1, wherein the method further comprises: An Al2O3 inner layer is prepared on the surface of the molybdenum alloy base by a magnetron sputtering method using an Al target.
3. The method of claim 1, wherein the method further comprises: The thickness of the Al2O3 inner layer is 1-5 μm, and the thickness of the Al2O3 inner layer and the outer layer blank is controlled to be 30-70 μm.
4. The method for preparing an interfacial nanocrystalline structure based multicomponent alloy oxidation resistant coating according to claim 1 or 3, characterized in that, When the first composite blank is annealed to obtain α-Al2O3 nanocrystals as an inner layer of the coating to obtain a second composite blank, the annealing atmosphere is an inert atmosphere, the heating rate is 4-6 ℃ / min, the annealing temperature is 500-800 ℃, and the holding time is 1-3 h.
5. The method of claim 1, wherein the method further comprises: Before the Al2O3 inner layer is prepared on the surface of the molybdenum alloy base by a magnetron sputtering method, the surface of the molybdenum alloy base is polished smooth and the oxide layer is removed, and then the surface of the molybdenum alloy base is cleaned, dried and then the Al2O3 inner layer is prepared on the surface of the molybdenum alloy base by a magnetron sputtering method.
6. The method of claim 1, wherein the method further comprises: The preparation process of the slurry for forming the slurry coating on the second composite blank comprises the following steps: Anhydrous ethanol is added to the components of the outer layer blank, and ball milling is performed at a ball milling speed of 290-310 rpm for 11.5-12.5 h to obtain the slurry, wherein the mass ratio of the components of the outer layer blank to the anhydrous ethanol is (4-6):
1.
7. The method of claim 6, wherein the method further comprises: After the slurry coating is coated on the second composite blank, the slurry coating is dried at 25-35 ℃ for 5.5-6.5 h.
8. The method of claim 1, wherein the method further comprises: The sintering aid is polyvinyl butyral ester.
9. The method of claim 1, wherein the method further comprises: The slurry coating is coated on the second composite blank by a spraying coating process.
10. An interfacial nanocrystalline structure based multicomponent alloy oxidation resistant coating, characterized in that, The multi-element alloy oxidation-resistant coating based on the interface nanocrystalline structure is prepared by any one of the preparation methods in claims 1-9.