Marine high-temperature corrosion environment resistant metal protective coating and preparation method thereof

Abstract

The invention discloses a preparation method of a metal protective coating capable of resisting a marine high-temperature corrosion environment, which comprises the following steps: doping 1-10% by mass of M2AX phase in the metal protective coating, and modifying the surface of the metal protective coating by femtosecond laser to obtain a surface modified layer with the thickness of about 15-20 microns, the surface roughness of less than 1 micron and the thickness of less than 10 microns. And surface transition metal elements are periodically and uniformly distributed. The components of the coating are regulated and controlled by doping the transition metal element oxide, and the high-temperature thermal stability of the coating is improved; then micro-melting polishing of the surface of the coating and cross-scale space ordered distribution of transition metal element oxides are realized through a femtosecond laser controllable heat accumulation effect, a corrosive medium can be preferentially adsorbed, and rapid formation and stable growth of a protective oxide film of the coating in a marine high-temperature corrosive environment are promoted; further, the coating with high stability, long service life and marine high-temperature corrosion environment resistance is obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of marine equipment corrosion and protection, and in particular to a metal protective coating resistant to marine high-temperature corrosion environments and a preparation method thereof. Background Art

[0002] The hot end components of deep-sea equipment power systems (such as ship gas turbines, carrier-based aircraft engines, etc.) face severe challenges from multi-field coupled extreme environments such as high temperature (≥900°C), high salt spray, and high sulfur / vanadium corrosion. Metal protective coatings are a key barrier to ensure the reliable operation of power systems, and their performance degradation directly affects the service life and combat effectiveness of equipment. Existing coating systems are prone to interfacial crack propagation under the thermal-mechanical-chemical coupling of the ocean. At the same time, the synergistic erosion of corrosive media such as oxygen, chlorine, sulfur, and vanadium leads to structural instability of the coating. For example, the life of a certain type of ship-based gas turbine blade was shortened to 50% of the design value due to high-temperature corrosion. Among various thermal protective coatings, NiCrAlY, NiCoCrAlY, or CoCrAlY coatings can form a dense, continuous, uniform, and highly corrosion-resistant protective thermally grown oxide (TGO) layer on the surface during service. This layer is primarily composed of Al2O3, effectively blocking the penetration corrosion of oxygen, chloride ions, and molten sulfate / vanadium salts. They can serve as both a bonding layer for thermal barrier coatings on turbine surfaces and as independent protective coatings for blades and combustion chamber inner walls, significantly improving the high-temperature corrosion resistance of hot-end components. However, facing the complex corrosion conditions of the ocean, the service life of NiCrAlY, NiCoCrAlY, or CoCrAlY coatings is significantly reduced. Improving the resistance of these metal protective coatings to high-temperature marine corrosion is urgent.

[0003] At present, many researchers are committed to the design of coating components and the use of some post-processing processes to improve the coating's resistance to high-temperature marine corrosion. The patent "NiSiAlY coating, its preparation method and application" (authorization number CN110158041B) proposes to introduce 2.4wt.% to 10wt.% Si elements into the coating to improve the coating's resistance to NaCl corrosion. However, the Si element may affect the high-temperature phase stability of the coating. The patent "Method for improving the resistance of transition metal modified MCrAlY coating to high-temperature sulfidation corrosion" (authorization number CN100577852C) proposes to introduce transition metal elements or transition metal oxides into the coating, which can greatly improve the resistance to high-temperature sulfidation corrosion. However, due to the strong activity of transition metal elements, large-sized aggregates may form inside the coating, which will deteriorate the performance of the coating. In addition, the patent "A thermal barrier coating resistant to marine salt spray corrosion and its preparation method" (application number CN119194440A) proposes the use of high-power continuous laser remelting to improve the coating's resistance to marine salt spray corrosion. However, the continuous laser power is relatively large (KW level), and there are thermal defects such as the introduction of microcracks, excessive thermal impact, and ablation damage to the coating surface. Summary of the Invention

[0004] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a metal protective coating resistant to high-temperature marine corrosion environment and a preparation method thereof, so as to improve the high-temperature phase stability of the metal protective coating, eliminate microscopic defects in the coating preparation process, avoid the thermal damage problem in traditional laser remelting, and a series of modification effects promote the rapid formation and stable growth of a protective oxide film on the coating surface in a high-temperature marine corrosion environment, thereby greatly extending the coating life.

[0005] According to a first aspect of the present invention, the present invention provides a metal protective coating resistant to marine high-temperature corrosion environments, comprising introducing 1-10% by mass of an M2AlC phase into the metal protective coating, wherein M is a transition metal element.

[0006] Preferably, the metal protective coating is any one or more of NiCrAlY, NiCoCrAlY or CoCrAlY.

[0007] Preferably, the transition metal element is any one or more of titanium (Ti), vanadium (V), molybdenum, (Mo) yttrium (Y), tantalum (Ta), niobium (Nb), hafnium (Hf), and erbium (Er).

[0008] Preferably, the metal protective coating is NiCoCrAlY, and 3% of Ta2AlC is introduced; the metal protective coating is NiCrAlY, and 5% of Mo2AlC is introduced; or the metal protective coating is CoCrAlY, and 8% of Nb2AlC is introduced.

[0009] According to the second aspect of the present invention, the present invention proposes a method for preparing a metal protective coating resistant to high-temperature marine corrosion environments, comprising introducing 1-10% by mass of an M2AlC phase into the metal protective coating; and then modifying the surface of the metal protective coating by femtosecond laser. Beneficial effects such as micro-melting and polishing of the coating surface, reorganization of the microstructure, and uniform distribution of transition metal elements are achieved, thereby forming a metal protective coating resistant to high-temperature marine corrosion environments. The present invention achieves coating component regulation by doping with transition metal oxides, thereby improving the high-temperature thermal stability of the coating; and then achieves micro-melting and polishing of the coating surface and orderly distribution of transition metal oxides across scales through the controllable thermal accumulation effect of a femtosecond laser, which can preferentially adsorb corrosive media and promote the rapid formation and stable growth of a protective oxide film of the coating in a high-temperature marine corrosion environment, thereby obtaining a highly stable and long-life coating resistant to high-temperature marine corrosion environments.

[0010] Preferably, the metal protective coating is any one or more of NiCrAlY, NiCoCrAlY or CoCrAlY.

[0011] Preferably, the M2AlC phase (M = transition metal element), the transition metal element is any one or more of titanium (Ti), vanadium (V), molybdenum, (Mo) yttrium (Y), tantalum (Ta), niobium (Nb), hafnium (Hf), and erbium (Er).

[0012] Preferably, the metal protective coating is prepared by any one of low-pressure plasma spraying, supersonic flame spraying or arc ion plating.

[0013] Preferably, the M2AlC phase (M = transition metal element) is doped into the metal protective coating powder in the form of ball milling mixing at a mass percentage of 1-10%, and the ideal metal protective coating is prepared by low-pressure plasma spraying, supersonic flame spraying, high-pressure plasma spraying, supersonic flame spraying or arc ion plating.

[0014] Preferably, the prepared metal protective coating is surface cleaned and then placed on a femtosecond laser processing platform, and the process parameters are controlled as follows: repetition frequency of 5 to 20 MHz, pulse width of 10 to 100 fs, spot diameter of 20 μm, laser wavelength of 1030 nm, and laser single pulse energy density of 0.5 to 5 J / cm 2 , the galvanometer scanning speed is 5~100mm / s.

[0015] Preferably, the femtosecond laser processing atmosphere is argon, and the gas flow rate is 10 to 15 L / min.

[0016] Preferably, the scanning strategy of the femtosecond laser is an orthogonal scanning strategy, and the scanning interval is 20 to 50 μm.

[0017] Compared with the prior art, the present invention has the following significant advantages:

[0018] In the present invention, a metal anti-coating layer is doped with the M2AlC phase (M = transition metal element). The M2AlC phase is a new type of material with a unique layered structure, characterized by high toughness, high damage tolerance, and high corrosion resistance. After the M2AlC phase is doped into the coating, in a corrosive environment, the Al element preferentially diffuses to the surface and selectively oxidizes to form a dense and protective Al2O3 protective layer; at the same time, the oxide of the transition metal element can be embedded in the oxide layer, further enhancing the density and adhesion of the protective layer. In addition, the layered structure of MAl2C promotes the continuous diffusion of Al, giving the oxide layer the ability to self-repair, thereby significantly improving the durability of the material in high-temperature corrosive environments.

[0019] In the present invention, femtosecond laser is used to modify the M2AlC phase doped metal anti-coating. The power of the femtosecond laser used is relatively small (less than 20W), and its pulse width is at the femtosecond laser level. The thermal effect is extremely small and the cooling rate is extremely high (10 7K / S), and can precisely control the size and distribution of transition metal elements by adjusting process parameters, can achieve micro-polishing of the coating surface and introduce rich crystal defects, and promote the establishment and growth of the protective oxide film of the coating.

[0020] In the present invention, highly stable and uniform transition metal element oxides can be induced to preferentially form on the surface of the MCrAlX coating on the surface of the metal protective coating, which can not only promote the nucleation of TGO in the transient oxidation stage, but also achieve a "pinning" effect in the steady-state oxidation stage. This will maximize the active element effect and achieve "controllable material composition, controllable element distribution, controllable microstructure, and controllable oxide growth behavior" for MCrAlY (M is at least one of Ni or Co), ultimately achieving improved resistance to high-temperature marine corrosion of the coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The macromorphology, surface micromorphology and cross-sectional micromorphology of the 3% Ta2AlC-NiCoCrAlY coating prepared by arc ion plating technology in Example 1 of the present invention;

[0022] Figure 2 The macromorphology, surface micromorphology and cross-sectional micromorphology of the 3% Ta2AlC-NiCoCrAlY coating prepared by arc ion plating technology using femtosecond laser treatment in Example 1 of the present invention;

[0023] Figure 3 Cross-sectional micromorphology of common NiCoCrAlY coating and 3% Ta2AlC-NiCoCrAlY prepared by femtosecond laser treatment arc ion plating technology after 10 hours of corrosion under 75% Na2SO4-25% V2O5 molten salt corrosion conditions in Example 1 of the present invention;

[0024] Figure 4 Cross-sectional micromorphology of a common NiCoCrAlY coating after 100 h of corrosion under 75% Na2SO4-25% V2O5 molten salt conditions in Example 1 of the present invention, and of a 3% Ta2AlC-NiCoCrAlY coating prepared by arc ion plating technology before and after femtosecond laser treatment. DETAILED DESCRIPTION

[0025] Hereinafter, the present invention will describe the technical solution in detail through specific embodiments. However, it should be clearly stated that these embodiments are provided for illustration only and are not to be construed as limiting the scope of the present invention.

[0026] Example 1

[0027] In this embodiment, the metal protective coating for high-temperature marine corrosion environment is NiCoCrAlY, into which 3% Ta2AlC is introduced (i.e., 3% by weight of NiCoCrAlY, and the remaining embodiments are similar). A 3% Ta2AlC-NiCoCrAlY coating is prepared by arc ion plating. The arc ion plating process is as follows: vacuum degree 0.008Pa, deposition temperature 350°C, arc current 60A, arc voltage 21V, bias voltage 285V, duty cycle 30%, workpiece distance 225mm, and the deposition process is appropriately adjusted according to the coating characteristics to form the desired metal protective coating. The results are shown in FIG. Figure 1 shown.

[0028] The 3% Ta2AlC-NiCoCrAlY coating was then subjected to femtosecond laser surface processing. The processing atmosphere was argon with an airflow rate of 12 L / min. The femtosecond laser processing process had a repetition rate of 12 MHz, a pulse width of 50 fs, a spot diameter of 20 μm, a laser wavelength of 1030 nm, and a laser single pulse energy density of 0.55 J / cm 2 The scanning speed of the galvanometer is 20 mm / s. The scanning strategy of the femtosecond laser is an orthogonal scanning strategy with a scanning pitch of 20 μm. The thickness of the modified layer is 15 μm, the surface roughness is 0.93 μm, and the transition metal elements on the surface are periodically and uniformly distributed. The periodicity is consistent with the scanning pitch of 20 μm. Figure 2 shown.

[0029] Then, a test was conducted in a simulated marine high-temperature corrosion environment: the obtained femtosecond laser-modified 3% Ta2AlC-NiCoCrAlY coating was coated with 75% Na2SO4-25% V2O5 corrosive molten salt at a coating density of 5 mg / cm 2 The high temperature corrosion temperature is 900℃ and the corrosion time is 10h and 100h. For comparison, the NiCoCrAlY coating prepared by common arc ion plating, whose preparation process is consistent with the 3% Ta2AlC-NiCoCrAlY described above, is subjected to the same high temperature corrosion test. Figure 3 As shown in the figure, after high-temperature corrosion, the common NiCoCrAlY coating completely fails and suffers from severe corrosion damage, with the corrosive medium penetrating the entire coating. However, the 3% Ta2AlC-NiCoCrAlY coating modified by a femtosecond laser proposed in the present invention remains intact, and the underlying oxide layer shows no obvious degradation. The common NiCoCrAlY coating suffers from severe corrosion after only 2 hours and cannot form an effective protective oxide film; however, the protective oxide film of the 3% Ta2AlC-NiCoCrAlY coating modified by a femtosecond laser proposed in the present invention remains dense and continuous after 100 hours of corrosion, as shown in the figure. Figure 4Therefore, the present invention proposes that the 3% Ta2AlC-NiCoCrAlY coating modified by femtosecond laser has good resistance to high-temperature marine corrosion.

[0030] Example 2

[0031] In this embodiment, the metal protective coating resistant to high-temperature marine corrosion environment is NiCrAlY, into which 5% Mo2AlC is introduced. A 5% Mo2AlC-NiCrAlY coating is prepared by a low-pressure plasma spraying process. The low-pressure plasma spraying process is as follows: current 1650A, voltage 51.6V, argon flow 110L / min, hydrogen flow 6L / min, pressure 40Kpa, spraying distance 450mm, and the deposition process is appropriately adjusted according to the coating characteristics to form the required metal protective coating. Subsequently, the 5% Mo2AlC-NiCrAlY coating is subjected to femtosecond laser surface processing. The processing atmosphere is argon, and the air flow rate is 12L / min. The femtosecond laser processing process is as follows: a repetition frequency of 15MHz, a pulse width of 90fs, a spot diameter of 20μm, a laser wavelength of 1030nm, and a laser single pulse energy density of 0.8J / cm 2 The scanning speed of the galvanometer was 15 mm / s. The femtosecond laser scanning strategy was orthogonal, with a scanning pitch of 30 μm. The resulting modified layer had a thickness of 20 μm and a surface roughness of 0.99 μm. The transition metal elements on the surface exhibited a periodic and uniform distribution, with this periodicity consistent with the scanning pitch of 30 μm.

[0032] Then, a test was conducted in a simulated marine high-temperature corrosion environment: the obtained femtosecond laser-modified 5% Mo2AlC-NiCrAlY coating was coated with 75% Na2SO4-25% V2O5 corrosive molten salt at a coating density of 5 mg / cm 2 , the high temperature corrosion temperature is 800℃, and the corrosion time is 10h and 100h. For comparison, the common low-pressure plasma sprayed NiCoCrAlY coating, whose preparation process is consistent with the 5% Mo2AlC-NiCrAlY described in this embodiment, was subjected to the same high temperature corrosion test. After high temperature corrosion, the common NiCrAlY coating completely failed, severe corrosion damage occurred, and the corrosive medium penetrated the entire coating. However, the 5% Mo2AlC-NiCrAlY coating modified by femtosecond laser proposed in the present invention remained intact, and the underlying oxide layer showed no obvious degradation. The common NiCrAlY coating suffered severe corrosion after only 2 hours and could not form an effective protective oxide film; while the 5% Mo2AlC-NiCrAlY coating modified by femtosecond laser proposed in the present invention maintained a dense and continuous protective oxide film after 100 hours of corrosion. Therefore, the 5% Mo2AlC-NiCrAlY coating modified by femtosecond laser proposed in the present invention has better resistance to marine high temperature corrosion.

[0033] Example 3

[0034] In this embodiment, the metal protective coating resistant to high-temperature marine corrosion environment is CoCrAlY, into which 8% Nb2AlC is introduced. The 8% Nb2AlC-CoCrAlY coating is prepared by supersonic flame spraying. The supersonic flame spraying process is: gas pressure 6.9MPa, oxygen flow 40L / min, propane flow 58L / min, powder feeding rate 35g / min, and the deposition process is appropriately adjusted according to the coating characteristics to form the required metal protective coating. The 8% Nb2AlC-CoCrAlY coating is then subjected to femtosecond laser surface processing. The processing atmosphere is argon, and the air flow rate is 12L / min. The femtosecond laser processing process is as follows: a repetition frequency of 12MHz, a pulse width of 50fs, a spot diameter of 20μm, a laser wavelength of 1030nm, and a laser single pulse energy density of 0.55J / cm 2 The scanning speed of the galvanometer was 20 mm / s. The femtosecond laser scanning strategy was orthogonal, with a scanning pitch of 20 μm. The resulting modified layer had a thickness of 15 μm and a surface roughness of 0.93 μm. The transition metal elements on the surface exhibited a periodic and uniform distribution, with this periodicity consistent with the 20 μm scanning pitch.

[0035] Then, a test was conducted in a simulated marine high-temperature corrosion environment: the obtained femtosecond laser-modified 8% Nb2AlC-CoCrAlY coating was coated with 75% Na2SO4-25% V2O5 corrosive molten salt at a coating density of 5 mg / cm 2 , the high-temperature corrosion temperature is 900℃, and the corrosion time is 10h and 100h. For comparison, a common supersonic flame sprayed NiCoCrAlY coating, whose preparation process is consistent with the 8% Nb2AlC-CoCrAlY described in this embodiment, was subjected to the same high-temperature corrosion test. After high-temperature corrosion, the common NiCrAlY coating completely failed, severe corrosion damage occurred, and the corrosive medium penetrated the entire coating. However, the femtosecond laser-modified 8% Nb2AlC-CoCrAlY coating proposed in the present invention remained intact, and the underlying oxide layer showed no obvious degradation. The common CoCrAlY coating suffered severe corrosion after only 2 hours and was unable to form an effective protective oxide film; while the femtosecond laser-modified 8% Nb2AlC-CoCrAlY coating proposed in the present invention maintained a dense and continuous protective oxide film after 100 hours of corrosion. Therefore, the femtosecond laser-modified 8% Nb2AlC-CoCrAlY coating proposed in the present invention has better resistance to marine high-temperature corrosion.

[0036] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A metal protective coating resistant to high-temperature marine corrosion environment, comprising introducing 1-10% by mass of an M2AlC phase into the metal protective coating, wherein M is a transition metal element.

2. The metal protective coating resistant to marine high temperature corrosion environment according to claim 1, wherein the metal protective coating is any one or more of NiCrAlY, NiCoCrAlY or CoCrAlY.

3. The metal protective coating resistant to marine high-temperature corrosion environment according to claim 1, wherein the transition metal element is any one or more of titanium (Ti), vanadium (V), molybdenum, (Mo) yttrium (Y), tantalum (Ta), niobium (Nb), hafnium (Hf), and erbium (Er).

4. The metal protective coating for resistance to high-temperature marine corrosion environment according to claim 1, wherein the metal protective coating is NiCoCrAlY and introduces 3% of Ta2AlC; the metal protective coating is NiCrAlY and introduces 5% of Mo2AlC; or the metal protective coating is CoCrAlY and introduces 8% of Nb2AlC.

5. A method for preparing a metal protective coating resistant to high-temperature marine corrosion environments according to claim 1, comprising introducing 1-10% by mass of an M2AlC phase into the metal protective coating; and then modifying the surface of the metal protective coating by femtosecond laser.

6. The method according to claim 5, wherein the metal protective coating is prepared by any one of low-pressure plasma spraying, supersonic flame spraying or arc ion plating.

7. The method according to claim 5, wherein the M2AlC phase is doped into the metal protective coating powder in the form of ball milling mixing in the form of 1-10% by mass, and the metal protective coating is prepared by low-pressure plasma spraying, high-velocity flame spraying, high-velocity flame spraying or arc ion plating.

8. The method according to claim 5, wherein the prepared metal protective coating is subjected to surface cleaning treatment, and then placed on a femtosecond laser processing platform for surface modification of the metal protective coating using a femtosecond laser, wherein the process parameters are controlled as follows: a repetition frequency of 5 to 20 MHz, a pulse width of 10 to 100 fs, a spot diameter of 20 μm, a laser wavelength of 1030 nm, and a laser single pulse energy density of 0.5 to 5 J / cm 2 , the galvanometer scanning speed is 5~100mm / s.

9. The method according to claim 5, wherein the femtosecond laser processing atmosphere is argon gas with a gas flow rate of 10 to 15 L / min.

10. The method according to claim 5, wherein the scanning strategy of the femtosecond laser is an orthogonal scanning strategy, and the scanning interval is 20 to 50 μm.

Images