Titanium alloy surface hot corrosion resistant coating and method of making and use

Abstract

The application provides a titanium alloy surface heat-resistant and corrosion-resistant coating, a preparation method and application, and belongs to the technical field of high-temperature protective coating preparation. The titanium alloy surface heat-resistant and corrosion-resistant coating is obtained by sequentially spraying a Ti / Al adhesive layer and a Ti-Al-Si composite coating on a titanium alloy base. The Ti-Al-Si composite coating is obtained by mechanically mixing titanium powder, aluminum powder and silicon powder, then spraying and granulating to form titanium-aluminum-silicon composite agglomerated powder, and then plasma spraying to obtain a Ti-Al-Si composite coating containing TiAl3, Ti5Si3 and Ti-Al-Si ternary compounds. The titanium alloy surface heat-resistant and corrosion-resistant coating has good heat-resistant and corrosion-resistant performance.

Description

Technical Field

[0001] This invention belongs to the field of high-temperature protective coating preparation technology, specifically relating to a heat-resistant corrosion-resistant coating for titanium alloy surfaces, its preparation method, and its application. Background Technology

[0002] Titanium alloys are widely used in the aerospace industry due to their excellent comprehensive properties, including low specific gravity, high specific strength, corrosion resistance, and wear resistance. These alloys are used in components such as compressor discs, blades, and casings in aircraft engines. However, when used in aircraft engine compressor discs and blades, titanium alloys often face high-temperature challenges. Currently, the operating temperature of titanium alloys is generally below 650℃. When the temperature exceeds 650℃, the titanium alloy surface faces high-temperature oxidation and hot corrosion, which significantly affects its performance. Surface coatings can provide high-temperature protection for hot-end components of gas turbines in the aerospace and modern energy industries.

[0003] To address the above issues, extensive research has been conducted both domestically and internationally on high-temperature protective coatings for titanium alloy surfaces. Among these, Ti-Al-Si composite coatings have received widespread attention due to their excellent high-temperature stability, good bonding with the titanium alloy substrate, and low diffusion caused by elemental similarity. Currently, Ti-Al-Si composite coatings are produced by ball milling a mixture of titanium powder, aluminum powder, and silicon powder in a molar ratio of 1:1:1 to obtain a mixed powder, which is then sprayed onto the titanium alloy surface to form the Ti-Al-Si composite coating, aiming to improve the high-temperature oxidation resistance of titanium alloys. However, in practical applications, titanium alloy surfaces face the problem of hot corrosion, and the Ti-Al-Si composite coatings prepared using existing technologies cannot improve the high-temperature hot corrosion resistance of titanium alloys.

[0004] Therefore, there is a need for a Ti-Al-Si composite coating with excellent heat corrosion resistance at high temperatures to improve the high-temperature heat corrosion resistance of titanium alloys. Summary of the Invention

[0005] To address the issue that existing Ti-Al-Si composite coatings cannot improve the high-temperature corrosion resistance of titanium alloys, this invention provides a Ti-Al-Si-based heat-resistant corrosion-resistant coating for titanium alloy surfaces and its preparation method.

[0006] To achieve the above objectives, the specific technical solution of the present invention is as follows.

[0007] The first aspect of this invention provides a heat-resistant corrosion-resistant coating for a titanium alloy surface. This coating is obtained by sequentially spraying a Ti / Al bonding layer and a Ti-Al-Si composite coating onto a titanium alloy substrate. The Ti-Al-Si coating of this invention can react with hot-corrosion-resistant sodium salts at 200℃ to 1100℃ to form a composite oxide of Na2O-Al2O3-TiO2-SiO2, thereby resisting hot corrosion. The sodium salt is at least one of NaCl and NaSO4.

[0008] In the Ti-Al-Si composite coating, the molar ratio of Ti, Al, and Si is 3:1–2:1–2. By controlling the Al content, a larger and denser Al2O3 layer can be formed under high-temperature conditions, hindering the penetration of hot-corrosion sodium salts and improving the coating's heat corrosion resistance. Controlling the Si content, on the one hand, forms a relatively dense SiO2 layer, and on the other hand, promotes the formation of Al2O3, further hindering the penetration of hot-corrosion salts and improving the coating's heat corrosion resistance.

[0009] In a preferred embodiment, the Ti-Al-Si composite coating is formed by mechanically mixing titanium powder, aluminum powder and silicon powder and then spraying granulation to form titanium-aluminum-silicon composite agglomerated powder. The composite agglomerated powder is then sprayed to obtain a coating containing TiAl3, Ti5Si3 and Ti-Al-Si ternary compounds.

[0010] This invention involves mechanically mixing titanium powder, aluminum powder, and silicon powder, followed by spray granulation to obtain a titanium-aluminum-silicon composite agglomerated powder. This powder is then sprayed to form a composite coating containing TiAl3, Ti5Si3, and Ti-Al-Si ternary compounds. Under high-temperature oxygen conditions, this coating can form a protective film of Al2O3 and SiO2, effectively mitigating the oxidation process. Under high-temperature thermal corrosion, the Ti-Al-Si composite coating reacts with molten salt to form a composite oxide of Na2O-Al2O3-TiO2-SiO2, which deposits in the micropores of the coating, thus hindering the inward diffusion of molten salt and achieving excellent resistance to thermal corrosion.

[0011] In a preferred embodiment, the Ti-Al-Si composite coating is obtained by ball milling a mixture of titanium powder, aluminum powder and silicon powder to obtain a mixed powder; the mixed powder is then spray-granulated to form a titanium-aluminum-silicon composite agglomerated powder, and after plasma spraying, a Ti-Al-Si composite coating containing TiAl3, Ti5Si3 and Ti-Al-Si ternary compounds is obtained.

[0012] In a preferred embodiment, the mass ratio of Ti to Al in the Ti / Al adhesive layer is 3:1.

[0013] In a preferred embodiment, the mechanical mixing is ball milling with a ball-to-material ratio of 3:1, a rotation speed of 200-400 rpm, and a time of 1 hour.

[0014] The granulation is spray granulation, and the parameters of the spray granulation are: atomizer speed 18000 rpm, air inlet temperature 250℃~300℃, and air outlet temperature 80℃~120℃.

[0015] In a preferred embodiment, the thickness of the Ti / Al adhesive layer is 80 μm to 100 μm; and the thickness of the Ti-Al-Si composite coating is 250 μm to 300 μm.

[0016] The second aspect of this invention provides a method for preparing a heat-resistant corrosion-resistant coating on a titanium alloy surface, wherein the heat-resistant corrosion-resistant coating on the titanium alloy surface is provided in the first aspect of this invention, and includes the following steps:

[0017] Titanium-aluminum mixed powder is sprayed onto a titanium alloy substrate to obtain a titanium alloy substrate with a Ti / Al bonding layer on the surface.

[0018] Titanium-aluminum-silicon composite agglomerate powder is sprayed onto a Ti / Al bonding layer to obtain a titanium alloy substrate with a Ti-Al-Si composite coating-Ti / Al bonding layer sequentially loaded on the surface, which is a heat-resistant corrosion-resistant coating on the titanium alloy surface.

[0019] In a preferred embodiment, the mass ratio of titanium powder to aluminum powder in the titanium-aluminum mixed powder is 3:1; wherein the particle size of titanium powder is 20μm to 50μm, the particle size of aluminum powder is 10μm to 30μm, and the particle size of silicon powder is 10μm to 30μm.

[0020] In a preferred embodiment, the spraying is plasma spraying;

[0021] The plasma spraying conditions for the Ti / Al adhesive layer are as follows: voltage 60V, current 500A, main gas Ar and auxiliary gas H2 flow rates 80L / min and 3L / min respectively, powder feeding gas Ar flow rate 5L / min, spraying distance 100mm, travel speed 10cm / s, and adhesive layer thickness 84μm.

[0022] In a preferred embodiment, the plasma spraying conditions for the Ti-Al-Si composite coating are as follows: voltage of 55-65V, current of 500-550A, main gas Ar and auxiliary gas H2 flow rates of 80-90L / min and 2.5-3.5L / min respectively, powder feeding gas Ar flow rate of 5-7L / min, spraying distance of 80-100mm, and travel speed of 10-20cm / s.

[0023] In a preferred embodiment, the titanium alloy substrate is subjected to progressive grinding, cleaning, and sandblasting to obtain a pretreated titanium alloy substrate.

[0024] The third aspect of the present invention provides an application of a heat-resistant and corrosion-resistant coating on the surface of a titanium alloy in the preparation of a heat-resistant and corrosion-resistant titanium alloy, wherein the heat-resistant and corrosion-resistant coating on the surface of the titanium alloy is provided by the first aspect of the present invention.

[0025] The heat-resistant titanium alloy has a heat resistance temperature of 200–1100℃; it can achieve heat corrosion resistance in at least one molten salt environment, such as NaCl or NaSO4. This is mainly because the heat-resistant coating on the titanium alloy surface reacts with NaCl and NaSO4 to form a composite oxide of Na2O-Al2O3-TiO2-SiO2, which is deposited in the micropores of the coating to hinder the inward diffusion of molten salt, thereby achieving heat corrosion resistance.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) The Ti-Al-Si composite coating of this invention can form a large number of dense Al2O3 layers at high temperatures by controlling the Al content, which hinders the penetration of hot corrosion salts and improves the heat corrosion resistance of the coating. The precise control of Si content can form relatively dense SiO2 on the one hand, and promote the formation of Al2O3 on the other hand, further hindering the penetration of hot corrosion salts and improving the heat corrosion resistance of the coating. In a high-temperature oxygen environment, the Ti-Al-Si composite coating can generate Al2O3 and SiO2 protective films, which can effectively alleviate the oxidation process; in the NaCl molten salt and NaSO4 molten salt environment, the Ti-Al-Si composite coating can generate Na2O-Al2O3-TiO2-SiO2 composite oxides, which are deposited in the micropores, thereby hindering the inward diffusion of molten salt and exhibiting good heat and corrosion resistance.

[0028] (2) The present invention uses reactive plasma spraying technology to prepare Ti-Al-Si composite coating. The production process is simple, efficient, and has good and stable performance. It can be prepared on a large scale and exhibits good heat and corrosion resistance. Attached Figure Description

[0029] Figure 1 This is a sample of the heat-resistant corrosion-resistant coating on the surface of the titanium alloy in Example 3 of the present invention.

[0030] Figure 2 This is an image showing the hot corrosion resistant coating on the titanium alloy surface and Na2SO4 molten salt being hot-corroded at 850°C for 100 hours in Example 3 of the present invention. Detailed Implementation

[0031] Exemplary embodiments of this disclosure will now be described in detail. However, it should be understood that this disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of this disclosure and to fully convey its scope to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0032] The present invention will now be described in detail with reference to embodiments.

[0033] The titanium alloy substrates used in the following examples are all Ti-6Al-4V, abbreviated as TC4, and the sample size is Φ16mm×6mm. Figure 1 As shown, its chemical composition is Fe≤0.30wt.%, C≤0.10wt.%, N≤0.05wt.%, H≤0.015wt.%, O≤0.20wt.%, Al 5.5~6.75wt.%, V 3.5~4.5wt.%, with the balance being Ti, totaling 100%.

[0034] Example 1

[0035] A heat-resistant corrosion-resistant coating for titanium alloy surface, wherein the heat-resistant corrosion-resistant coating for titanium alloy surface is obtained by sequentially spraying a Ti / Al bonding layer and a Ti-Al-Si composite coating onto a titanium alloy substrate;

[0036] In the Ti-Al-Si composite coating, the molar ratio of Ti, Al and Si is 3:2:1;

[0037] In the Ti / Al binder layer, the mass ratio of Ti to Al is 3:1.

[0038] The Ti-Al-Si composite coating is obtained by mechanically mixing titanium powder, aluminum powder and silicon powder and then spraying granulation to form titanium-aluminum-silicon composite agglomerated powder. The composite agglomerated powder is then sprayed to obtain a coating containing TiAl3, Ti5Si3 and Ti-Al-Si ternary compounds.

[0039] The method for preparing the above-mentioned Ti-Al-Si based heat-resistant corrosion-resistant coating on the surface of titanium alloy includes the following steps:

[0040] S1. After grinding the titanium alloy substrate step by step, ultrasonically clean it with alcohol for 20 minutes and blow it dry; then sandblast the surface of the titanium alloy substrate for 10 minutes to obtain the surface roughened titanium alloy substrate.

[0041] S2. Place the titanium-aluminum mixed powder in an oven and keep it at 80℃ for 2 hours. Then take out the powder and put it into a powder feeder. Use plasma spraying to spray the titanium-aluminum mixed powder onto the titanium alloy surface to obtain a Ti / Al intermediate bonding layer with a thickness of 84μm. After preparation, take it out and let it stand at room temperature for later use.

[0042] The parameters for plasma spraying are: voltage 60V, current 500A, main gas Ar and auxiliary gas H2 flow rates 80L / min and 3L / min respectively, powder feeding gas Ar flow rate 5L / min, spraying distance 100mm, and travel speed 10cm / s.

[0043] S3. Titanium powder, aluminum powder and silicon powder are mixed in a molar ratio of 3:2:1. After mechanical mixing, the mixed powder is sprayed to obtain titanium-aluminum-silicon composite agglomerated powder. The powder is placed in an oven and kept at 80°C for 2 hours. Then the powder is taken out and placed in a powder feeder. The titanium-aluminum-silicon composite agglomerated powder is sprayed onto the surface of the Ti / Al bonding layer by plasma spraying to obtain a Ti-Al-Si composite coating with a thickness of 284μm.

[0044] The parameters for plasma spraying are: voltage 60V, current 500A, main gas Ar and auxiliary gas H2 flow rates 80L / min and 3L / min respectively, powder feeding gas Ar flow rate 3L / min, spraying distance 100mm, and travel speed 12cm / s.

[0045] Example 2

[0046] A heat-resistant corrosion-resistant coating for titanium alloy surface, wherein the heat-resistant corrosion-resistant coating for titanium alloy surface is obtained by sequentially spraying a Ti / Al bonding layer and a Ti-Al-Si composite coating onto a titanium alloy substrate;

[0047] In the Ti-Al-Si composite coating, the molar ratio of Ti, Al and Si is 3:1:1;

[0048] In the Ti / Al binder layer, the mass ratio of Ti to Al is 3:1.

[0049] The Ti-Al-Si composite coating is obtained by mechanically mixing titanium powder, aluminum powder and silicon powder and then spraying granulation to form titanium-aluminum-silicon composite agglomerated powder. The composite agglomerated powder is then sprayed to obtain a coating containing TiAl3, Ti5Si3 and Ti-Al-Si ternary compounds.

[0050] The method for preparing the above-mentioned Ti-Al-Si based heat-resistant corrosion-resistant coating on the surface of titanium alloy includes the following steps:

[0051] S1. After grinding the titanium alloy substrate step by step, ultrasonically clean it with alcohol for 20 minutes and blow it dry; then sandblast the surface of the titanium alloy substrate for 10 minutes to obtain the surface roughened titanium alloy substrate.

[0052] S2. Place the nickel-aluminum mixed powder in an oven and keep it at 80°C for 2 hours. Then, take out the powder and put it into a powder feeder. Use plasma spraying to spray the titanium-aluminum mixed powder onto the titanium alloy surface to obtain a Ti / Al intermediate bonding layer with a thickness of 90μm. After preparation, take it out and let it stand at room temperature for later use.

[0053] The parameters for plasma spraying are: voltage 60V, current 500A, main gas Ar and auxiliary gas H2 flow rates 80L / min and 3L / min respectively, powder feeding gas Ar flow rate 5L / min, spraying distance 100mm, and travel speed 10cm / s.

[0054] S3. Titanium powder, aluminum powder and silicon powder are mixed in a molar ratio of 3:1:1. After mechanical mixing, the mixed powder is sprayed to obtain titanium-aluminum-silicon composite agglomerated powder. The powder is placed in an oven and kept at 80°C for 2 hours. Then the powder is taken out and placed in a powder feeder. The titanium-aluminum-silicon composite agglomerated powder is sprayed onto the surface of the Ni / Al bonding layer by plasma spraying to obtain a Ti-Al-Si composite coating with a thickness of 290μm.

[0055] The parameters for plasma spraying are: voltage 60V, current 500A, main gas Ar and auxiliary gas H2 flow rates 80L / min and 3L / min respectively, powder feeding gas Ar flow rate 3L / min, spraying distance 100mm, and travel speed 12cm / s.

[0056] Example 3

[0057] A heat-resistant corrosion-resistant coating for titanium alloy surface, wherein the heat-resistant corrosion-resistant coating for titanium alloy surface is obtained by sequentially spraying a Ti / Al bonding layer and a Ti-Al-Si composite coating onto a titanium alloy substrate;

[0058] In the Ti-Al-Si composite coating, the molar ratio of Ti, Al and Si is 3:1:2;

[0059] In the Ti / Al binder layer, the mass ratio of Ti to Al is 3:1.

[0060] The Ti-Al-Si composite coating is obtained by mechanically mixing titanium powder, aluminum powder and silicon powder and then spraying granulation to form titanium-aluminum-silicon composite agglomerated powder. The composite agglomerated powder is then sprayed to obtain a coating containing TiAl3, Ti5Si3 and Ti-Al-Si ternary compounds.

[0061] The method for preparing the above-mentioned Ti-Al-Si based heat-resistant corrosion-resistant coating on the surface of titanium alloy includes the following steps:

[0062] S1. After grinding the titanium alloy substrate step by step, ultrasonically clean it with alcohol for 20 minutes and blow it dry; then sandblast the surface of the titanium alloy substrate for 10 minutes to obtain the surface roughened titanium alloy substrate.

[0063] S2. Place the nickel-aluminum mixed powder in an oven and keep it at 80°C for 2 hours. Then, take out the powder and put it into a powder feeder. Use plasma spraying to spray the nickel-aluminum mixed powder onto the surface of the titanium alloy to obtain a Ti / Al intermediate bonding layer with a thickness of 90μm. After preparation, take it out and let it stand at room temperature for later use.

[0064] The parameters for plasma spraying are: voltage 60V, current 500A, main gas Ar and auxiliary gas H2 flow rates 80L / min and 3L / min respectively, powder feeding gas Ar flow rate 5L / min, spraying distance 100mm, and travel speed 10cm / s.

[0065] S3. Titanium powder, aluminum powder, and silicon powder are mixed in a molar ratio of 3:1:2. After mechanical mixing, the mixture is spray-granulated to obtain titanium-aluminum-silicon composite agglomerated powder. The powder is then placed in an oven and kept at 80°C for 2 hours. Afterward, the powder is removed and placed in a powder feeder. Plasma spraying is then used to coat the Ni / Al bonding layer with the titanium-aluminum-silicon composite agglomerated powder, resulting in a Ti-Al-Si composite coating with a thickness of 280 μm. Figure 1 As shown;

[0066] The parameters for plasma spraying are: voltage 60V, current 500A, main gas Ar and auxiliary gas H2 flow rates 80L / min and 3L / min respectively, powder feeding gas Ar flow rate 5L / min, spraying distance 100mm, and travel speed 15cm / s.

[0067] Example 4

[0068] A heat-resistant corrosion-resistant coating for titanium alloy surface, wherein the heat-resistant corrosion-resistant coating for titanium alloy surface is obtained by sequentially spraying a Ti / Al bonding layer and a Ti-Al-Si composite coating onto a titanium alloy substrate;

[0069] In the Ti-Al-Si composite coating, the molar ratio of Ti, Al, and Si is 3:1:1.5;

[0070] In the Ti / Al binder layer, the mass ratio of Ti to Al is 3:1.

[0071] The Ti-Al-Si composite coating is obtained by mechanically mixing titanium powder, aluminum powder and silicon powder and then spraying granulation to form titanium-aluminum-silicon composite agglomerated powder. The composite agglomerated powder is then sprayed to obtain a coating containing TiAl3, Ti5Si3 and Ti-Al-Si ternary compounds.

[0072] The method for preparing the above-mentioned Ti-Al-Si based heat-resistant corrosion-resistant coating on the surface of titanium alloy includes the following steps:

[0073] S1. After grinding the titanium alloy substrate step by step, ultrasonically clean it with alcohol for 20 minutes and blow it dry; then sandblast the surface of the titanium alloy substrate for 10 minutes to obtain the surface roughened titanium alloy substrate.

[0074] S2. Place the nickel-aluminum mixed powder in an oven and keep it at 80°C for 2 hours. Then, take out the powder and put it into a powder feeder. Use plasma spraying to spray the nickel-aluminum mixed powder onto the surface of the titanium alloy to obtain a Ti / Al intermediate bonding layer with a thickness of 100μm. After preparation, take it out and let it stand at room temperature for later use.

[0075] The parameters for plasma spraying are: voltage 60V, current 500A, main gas Ar and auxiliary gas H2 flow rates 80L / min and 3L / min respectively, powder feeding gas Ar flow rate 5L / min, spraying distance 100mm, and travel speed 10cm / s.

[0076] S3. Titanium powder, aluminum powder and silicon powder are mixed in a molar ratio of 3:1:1.5. After mechanical mixing, the mixed powder is sprayed to obtain titanium-aluminum-silicon composite agglomerated powder. The powder is placed in an oven and kept at 80°C for 2 hours. Then the powder is taken out and placed in a powder feeder. The titanium-aluminum-silicon composite agglomerated powder is sprayed onto the surface of the Ni / Al bonding layer by plasma spraying to obtain a Ti-Al-Si composite coating with a thickness of 270μm.

[0077] The parameters for plasma spraying are: voltage 60V, current 500A, main gas Ar and auxiliary gas H2 flow rates 80L / min and 3L / min respectively, powder feeding gas Ar flow rate 5L / min, spraying distance 100mm, and travel speed 20cm / s.

[0078] Example 5

[0079] A heat-resistant corrosion-resistant coating for titanium alloy surface, wherein the heat-resistant corrosion-resistant coating for titanium alloy surface is obtained by sequentially spraying a Ti / Al bonding layer and a Ti-Al-Si composite coating onto a titanium alloy substrate;

[0080] In the Ti-Al-Si composite coating, the molar ratio of Ti, Al, and Si is 3:1.5:1;

[0081] In the Ti / Al binder layer, the mass ratio of Ti to Al is 3:1.

[0082] The Ti-Al-Si composite coating is obtained by mechanically mixing titanium powder, aluminum powder and silicon powder and then spraying granulation to form titanium-aluminum-silicon composite agglomerated powder. The composite agglomerated powder is then sprayed to obtain a coating containing TiAl3, Ti5Si3 and Ti-Al-Si ternary compounds.

[0083] The method for preparing the above-mentioned Ti-Al-Si based heat-resistant corrosion-resistant coating on the surface of titanium alloy includes the following steps:

[0084] S1. After grinding the titanium alloy substrate step by step, ultrasonically clean it with alcohol for 20 minutes and blow it dry; then sandblast the surface of the titanium alloy substrate for 10 minutes to obtain the surface roughened titanium alloy substrate.

[0085] S2. Place the nickel-aluminum mixed powder in an oven and keep it at 80°C for 2 hours. Then, take out the powder and put it into a powder feeder. Use plasma spraying to spray the nickel-aluminum mixed powder onto the surface of the titanium alloy to obtain a Ti / Al intermediate bonding layer with a thickness of 90μm. After preparation, take it out and let it stand at room temperature for later use.

[0086] The parameters for plasma spraying are: voltage 60V, current 500A, main gas Ar and auxiliary gas H2 flow rates 80L / min and 3L / min respectively, powder feeding gas Ar flow rate 5L / min, spraying distance 100mm, and travel speed 10cm / s.

[0087] S3. Titanium powder, aluminum powder and silicon powder are mixed in a molar ratio of 3:1.5:1. After mechanical mixing, the mixed powder is sprayed to obtain titanium-aluminum-silicon composite agglomerated powder. The powder is placed in an oven and kept at 80°C for 2 hours. Then the powder is taken out and placed in a powder feeder. The titanium-aluminum-silicon composite agglomerated powder is sprayed onto the surface of the Ni / Al bonding layer by plasma spraying to obtain a Ti-Al-Si composite coating with a thickness of 290μm.

[0088] The parameters for plasma spraying are: voltage 60V, current 500A, main gas Ar and auxiliary gas H2 flow rates 80L / min and 3L / min respectively, powder feeding gas Ar flow rate 5L / min, spraying distance 100mm, and travel speed 20cm / s.

[0089] The above Examples 1 to 5 all prepared a heat-resistant corrosion-resistant coating on the surface of titanium alloy. The high-temperature performance and heat corrosion resistance of the heat-resistant corrosion-resistant coating on the surface of titanium alloy were measured below.

[0090] 1. High-temperature performance test of heat-resistant corrosion-resistant coating on titanium alloy surface

[0091] The heat-resistant corrosion-resistant coatings on the titanium alloy surface prepared in Examples 1 to 5 were oxidized at 850°C for 100 hours each, with each cycle lasting 10 hours. The samples were cooled in the furnace, removed, and weighed. Ten cycles were performed in total. The experimental apparatus was a box-type resistance furnace. The oxidation weight gain data are shown in Table 1. As can be seen from Table 1, the oxidation rate of the heat-resistant corrosion-resistant coating on the titanium alloy surface is relatively low, and it has reached the level of complete oxidation resistance.

[0092] Table 1. Oxidation weight gain data of the heat-resistant corrosion-resistant coatings on the titanium alloy surface in Examples 1 to 5.

[0093]

[0094]

[0095] 2. Hot corrosion resistance of Ti-Al-Si based hot corrosion resistant coating on titanium alloy surface

[0096] Using the heat-resistant corrosion-resistant coating on the titanium alloy surface prepared in Example 1 as the experimental sample, a corrosion agent was uniformly spread on both the uncoated titanium alloy substrate and the Ti-Al-Si-based heat-resistant corrosion-resistant coating on the titanium alloy surface in Example 1. The corrosion agent was Na2SO4, and the concentration of the corrosion agent was 5 mg / cm³. 2 The test instrument was a box-type resistance furnace, the test temperature was 850℃, and the test time was 100h. Each 10h period was a cycle in which the sample was cooled in the furnace. There were ten cycles in total. The sample was cooled with the furnace. After cooling, the sample was boiled in deionized water until the salt film remaining on the sample surface was completely dissolved.

[0097] like Figure 2 As shown, from Figure 2 As can be seen from the surface morphology of the substrate and coating after hot corrosion, after 100 hours of hot corrosion on the substrate, a large amount of oxide film peeled off, macroscopic cracks appeared, and numerous corrosion pits were formed on the oxide film surface, indicating severe hot corrosion. In contrast, after 100 hours of hot corrosion, the Ti-Al-Si composite coating showed no obvious visible cracks or corrosion pits on the oxide film surface, and the oxide film did not peel off, demonstrating excellent hot corrosion resistance.

[0098] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent substitutions, and improvements made by those skilled in the art to the above embodiments without departing from the scope of the technical solution of the present invention, based on the technical essence of the present invention, shall still fall within the protection scope of the technical solution of the present invention.

Claims

1. A heat-resistant corrosion-resistant coating for titanium alloy surfaces, characterized in that, The heat-resistant corrosion-resistant coating on the titanium alloy surface is obtained by sequentially spraying a Ti / Al bonding layer and a Ti-Al-Si composite coating onto a titanium alloy substrate. In the Ti-Al-Si composite coating, the molar ratio of Ti, Al and Si is 3:1~2:1~2; The Ti-Al-Si composite coating is obtained by ball milling a mixture of titanium powder, aluminum powder, and silicon powder to obtain a mixed powder; the mixed powder is then spray-granulated to form a titanium-aluminum-silicon composite agglomerated powder, and plasma-sprayed to obtain a Ti-Al-Si composite coating containing TiAl3, Ti5Si3, and Ti-Al-Si ternary compounds; in the Ti / Al bonding layer, the mass ratio of Ti to Al is 3:

1. The heat corrosion resistance mentioned refers to resistance to Na2SO4 corrosion.

2. The heat-resistant corrosion-resistant coating on the titanium alloy surface according to claim 1, characterized in that, The thickness of the Ti / Al adhesive layer is 80μm~100μm; the thickness of the Ti-Al-Si composite coating is 250μm~300μm.

3. A method for preparing a heat-resistant corrosion-resistant coating on a titanium alloy surface as described in claim 2, characterized in that, Includes the following steps: Titanium-aluminum mixed powder is sprayed onto a pretreated titanium alloy substrate to obtain a titanium alloy substrate with a Ti / Al bonding layer on the surface. Titanium-aluminum-silicon composite agglomerate powder was sprayed onto the Ti / Al bonding layer of the titanium alloy substrate to obtain a Ti-Al-Si-based heat-resistant corrosion-resistant coating on the surface of the titanium alloy.

4. The method for preparing a heat-resistant corrosion-resistant coating on a titanium alloy surface according to claim 3, characterized in that, In the titanium-aluminum mixed powder, the mass ratio of titanium powder to aluminum powder is 3:

1.

5. The method for preparing a heat-resistant corrosion-resistant coating on a titanium alloy surface according to claim 3, characterized in that, The spraying is plasma spraying; The plasma spraying conditions for the Ti / Al bonding layer are as follows: voltage 60V, current 500A, main gas Ar and auxiliary gas H2 flow rates 80L / min and 3L / min respectively, powder feeding gas Ar flow rate 5L / min, spraying distance 100mm, and travel speed 10cm / s. The plasma spraying conditions for the Ti-Al-Si composite coating are as follows: voltage 55V~65V, current 500A~550A, main gas Ar and auxiliary gas H2 flow rates 80L / min~90L / min and 2.5L / min~3.5L / min respectively, powder feeding gas Ar flow rate 5L / min~7L / min, spraying distance 80mm~100mm, and travel speed 10cm / s~20cm / s.

6. The method for preparing a heat-resistant corrosion-resistant coating on a titanium alloy surface according to claim 3, characterized in that, The preparation process of the pretreated titanium alloy matrix is ​​as follows: After the titanium alloy substrate is polished in stages, it is cleaned and sandblasted to obtain a pretreated titanium alloy substrate.

7. The application of the heat-resistant corrosion-resistant coating on the titanium alloy surface as described in claim 2 in the preparation of heat-resistant and corrosion-resistant titanium alloys.

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