W-Re alloy with anti-ablation composite coating on surface and method for preparing anti-ablation composite coating on surface of W-Re alloy

Abstract

According to the W-Re alloy with the anti-ablation composite coating on the surface and the method for preparing the anti-ablation composite coating on the surface of the W-Re alloy, a tungsten oxide layer and a high-entropy alloy coating are sequentially arranged on the surface of an alloy matrix from inside to outside, the high-entropy alloy coating is (WMoNbTaHf) Cx, and x ranges from 1 wt% to 3 wt%. And the anti-ablation temperature of the anti-ablation coating is improved.

Description

Technical Field

[0001] The invention relates to the technical field of W-Re alloy anti-ablation composite coating, in particular to a W-Re alloy having an anti-ablation composite coating on its surface and a method for preparing the anti-ablation composite coating on the surface of the W-Re alloy. Background Art

[0002] As the Mach number of advanced aircraft increases and the specific impulse of high-thrust rockets increases, the service temperature of hot-end components increases, and higher and higher requirements are placed on the refractory ablation resistance. W-Re alloy (tungsten-rhenium alloy) is a refractory alloy. It is a solid solution-strengthened alloy with W (tungsten) as the matrix and Re (rhenium) as the composition. Due to its excellent high-temperature performance and physical properties, it is mostly used in hot-end components of aerospace. In order to improve the ablation resistance of W-Re, sintering, embedding infiltration, plasma spraying, etc. are often used to prepare ablation-resistant composite coatings (such as tungsten oxide coatings, silicides, aluminides, carbides, borides, etc.) on its surface.

[0003] However, as the service temperature of the hot end components increases to 2200℃ or even 3000℃, the applicant found in the study that in the extremely high temperature environment of 3000℃, the tungsten oxide coating on the surface of the tungsten-rhenium alloy showed poor bonding and brittle cracking problems. Under the scouring of high-temperature and high-speed airflow, the anti-ablation composite coating suffered from brittle cracking and peeling failure. Even if a ceramic layer is applied on the surface of the tungsten oxide coating, its brittleness cannot be improved, that is, the overall anti-ablation composite coating shows brittleness. Summary of the invention

[0004] In order to solve the problems of poor bonding strength and brittle cracking of tungsten oxide coating on the surface of tungsten-rhenium alloy in the prior art, the present invention provides a W-Re alloy with an anti-ablation composite coating on the surface and a method for preparing the anti-ablation composite coating on the surface of the W-Re alloy, thereby improving the brittleness problem of the tungsten oxide coating on the surface of the W-Re alloy and increasing the anti-ablation temperature of the anti-ablation composite coating.

[0005] In order to achieve the above-mentioned purpose, the specific scheme adopted by the present invention is: a W-Re alloy having an anti-ablation composite coating on the surface, a tungsten oxide layer and a high entropy alloy coating are arranged on the surface of the alloy substrate from the inside to the outside, and the high entropy alloy coating is (WMoNbTaHf)Cx, and x=1~3wt%.

[0006] As an optimization solution for the above-mentioned W-Re alloy having an anti-ablation composite coating on its surface: the thickness of the tungsten oxide layer is 30-80 μm.

[0007] As another optimization scheme for the above-mentioned W-Re alloy having an anti-ablation composite coating on its surface: the thickness of the high entropy alloy coating is 50-100 μm.

[0008] A method for preparing an anti-ablation composite coating on a W-Re alloy surface, wherein the surface of an alloy substrate is treated and a tungsten oxide layer is formed on the surface by micro-arc oxidation;

[0009] Polishing the tungsten oxide layer;

[0010] 20wt%-50wt% of tungsten powder, 10wt%-30wt% of molybdenum powder, 5wt%-20wt% of niobium powder, 10wt%-30wt% of tantalum powder, 1wt%-20wt% of hafnium powder and 1wt%-3wt% of carbon powder are mixed to obtain a uniform powder, and the mixed powder is sprayed on the surface of the tungsten oxide layer to form a high entropy alloy coating.

[0011] As an optimization scheme for the method of preparing an ablation-resistant composite coating on the surface of the W-Re alloy, the process of forming a tungsten oxide layer on the surface of the W-Re alloy by micro-arc oxidation is as follows: the W-Re alloy is used as an anode, stainless steel is selected as a cathode, and the W-Re alloy and stainless steel are placed in a Na2SiO3 electrolyte at a temperature of 5-80°C for micro-arc oxidation. The process parameters of the micro-arc oxidation are: voltage 400-600V, current density 1-10A / dm 2 .

[0012] As another optimization scheme for the method for preparing an ablation-resistant composite coating on the surface of the W-Re alloy mentioned above: the pH value of the Na2SiO3 electrolyte is 12-14.

[0013] As another optimization scheme for the method of preparing an ablation-resistant composite coating on the surface of the W-Re alloy, the grinding depth of the tungsten oxide layer is 5-10 μm.

[0014] As another optimization scheme of the method for preparing an ablation-resistant composite coating on the surface of the above-mentioned W-Re alloy: the particle size of tungsten, molybdenum, niobium, tantalum and hafnium powders is 50-100nm, and the particle size of carbon powder is 100-200nm.

[0015] As another optimization scheme for the method of preparing an ablation-resistant composite coating on the surface of the W-Re alloy mentioned above, the mixed powder is sprayed on the surface of the tungsten oxide layer by high-speed plasma thermal spraying.

[0016] As another optimization scheme for the method of preparing an ablation-resistant composite coating on the surface of the W-Re alloy mentioned above, the process parameters of the high-speed plasma thermal spraying method are: a flame velocity of 500-1200 m / s, and a mixed powder spraying velocity of 200-700 m / s.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The invention provides a W-Re alloy with an anti-ablation composite coating on its surface and a method for preparing the anti-ablation composite coating on the surface of the W-Re alloy. The anti-ablation composite coating comprises a tungsten oxide layer and a high entropy alloy coating arranged in sequence from the inside to the outside of an alloy substrate surface. Specifically, micro-arc oxidation is performed on the surface of the alloy substrate to instantly grow a firmly bonded tungsten oxide layer in situ on the surface of the alloy substrate; a high entropy alloy coating of (WMoNbTaHf)Cx is sprayed on the tungsten oxide layer to fill the micropores in the tungsten oxide layer. At the same time, tungsten oxide as a second phase particle strengthens the hardness and bonding force of the high entropy alloy coating, improves the bonding force of the coating, thereby improving the brittleness problem of the tungsten oxide layer, improves the stability of the high entropy alloy coating, and improves the service life and service temperature of the anti-ablation composite coating; C added to the high entropy alloy coating will preferentially react with Hf to form an HfC reinforcing phase, further improving the anti-ablation temperature of the anti-ablation composite coating.

[0019] The technical solution of the present invention is further elaborated in detail below in conjunction with specific embodiments. The parts not described and disclosed in detail in the following embodiments of the present invention should be understood as the existing technology known or should be known to those skilled in the art, such as how to prepare an alloy matrix. DETAILED DESCRIPTION

[0021] Example 1

[0022] A W-Re alloy with an anti-ablation composite coating on the surface, wherein a tungsten oxide layer and a high entropy alloy coating are sequentially arranged on the surface of the alloy substrate from the inside to the outside, wherein the thickness of the tungsten oxide layer is 30-80 μm; the thickness of the high entropy alloy coating is 50-100 μm, and the high entropy alloy coating is (WMoNbTaHf)Cx, and x=1-3wt%. A firmly bonded tungsten oxide layer is in situ grown on the surface of the alloy substrate, and a high entropy alloy coating is sprayed on the surface of the tungsten oxide to fill the micropores in the tungsten oxide layer. The tungsten oxide, as a second phase particle, strengthens the hardness and bonding force of the high entropy alloy coating, improves the bonding force of the coating, thereby improving the brittleness of the tungsten oxide layer, and at the same time, improves the stability of the high entropy alloy coating. The synergistic strengthening effect of the tungsten oxide layer and the high entropy alloy coating effectively improves the anti-ablation performance of the W-Re alloy, and the C atoms in the high entropy alloy coating preferentially react with Hf to generate an HfC ceramic reinforcement phase, thereby improving the anti-ablation temperature and density of the anti-ablation composite coating.

[0023] Example 2

[0024] A method for preparing an ablation-resistant composite coating on a W-Re alloy surface, wherein a tungsten oxide layer is formed on the surface of an alloy substrate by micro-arc oxidation, and a high-entropy alloy coating is sprayed on the tungsten oxide layer by a high-speed plasma spraying method. Specifically, micro-arc oxidation refers to the use of arc discharge to enhance the reaction at the anode on the basis of anodic oxidation, thereby forming a high-quality tungsten oxide layer on the surface of the alloy substrate. The tungsten oxide layer is formed by in-situ growth on the surface of the alloy substrate, and has a strong bonding force with the alloy substrate. High-speed plasma spraying uses an ion arc as a heat source to heat a high-entropy alloy powder to a semi-molten state, and sprays it at a high speed onto the tungsten oxide layer to form a firmly attached high-entropy alloy coating. Tungsten oxide, as a second-phase ion, strengthens the interface strength between the alloy substrate and the high-entropy alloy coating, improves the bonding force of the ablation-resistant composite coating, and thus improves the brittleness of the tungsten oxide coating.

[0025] The specific steps include:

[0026] The surface of the alloy substrate is treated by mechanical polishing and alcohol cleaning to remove surface impurities; then a tungsten oxide layer is formed on its surface by micro-arc oxidation. Specifically, the W-Re alloy is used as the anode, stainless steel is selected as the cathode, and the W-Re alloy and stainless steel are placed in a Na2SiO3 electrolyte with a temperature of 5-80°C and a pH of 12-14 for micro-arc oxidation. The process parameters of micro-arc oxidation are: voltage 400-600V, current density 1-10A / dm 2 The time of micro-arc oxidation is 10-60min. After the micro-arc oxidation is completed, the W-Re alloy is taken out from the electrolyte and rinsed with clean water to remove residual electrolyte and impurities.

[0027] The tungsten oxide layer is polished to a depth of 5-10 μm to remove the porous structure on the surface of the tungsten oxide layer. After polishing, the surface of the tungsten oxide layer is wiped with alcohol.

[0028] 20wt%-50wt% of tungsten powder, 10wt%-30wt% of molybdenum powder, 5wt%-20wt% of niobium powder, 10wt%-30wt% of tantalum powder, 1wt%-20wt% of hafnium powder and 1wt%-3wt% of carbon powder are mixed to obtain a uniform powder, wherein the particle size of the tungsten, molybdenum, niobium, tantalum and hafnium powders is 50-100nm, and the particle size of the carbon powder is 100-200nm. The tungsten, molybdenum, niobium, tantalum, hafnium and carbon powders are uniformly mixed by mechanical ball milling to obtain a mixed powder; and the mixed powder is sprayed on the surface of the tungsten oxide layer to form The high entropy alloy coating adopts a high-speed plasma thermal spraying method to spray a mixed powder on the surface of a tungsten oxide layer to form a high entropy alloy coating. The process parameters of the high-speed plasma thermal spraying method are: a flame velocity of 500-1200m / s, a mixed powder spraying velocity of 200-700m / s, and a spraying time of 10-30min; high-temperature plasma melts the mixed powder to form a hot slurry that is sprayed on the surface of the tungsten oxide layer to form (WMoNbTaHf)Cx (x=1-3wt%) on the surface; after the spraying is completed, the high entropy alloy coating is cooled.

[0029] In this embodiment, a method for preparing an anti-ablation composite coating on a W-Re alloy surface comprises the following steps:

[0030] The surface of the alloy substrate with a size of φ40×10mm was mechanically polished and cleaned with alcohol; then, the treated alloy substrate was used as the anode and the stainless steel was used as the cathode. The electrodes were placed in a Na2SiO3 electrolyte with a pH of 12, and the electrolyte temperature was adjusted to 40°C, the voltage to 400V, and the current density to 5A / dm 2 The micro-arc oxidation time is 40 minutes, and a tungsten oxide layer with a thickness of 60 μm is formed on the surface of the alloy substrate; the alloy substrate after micro-arc oxidation is taken out from the electrolyte and rinsed with clean water.

[0031] The tungsten oxide layer was polished to a depth of 5 μm, and the polished tungsten oxide layer was wiped with alcohol.

[0032] 80nm tungsten powder (50wt%), molybdenum powder (30wt%), niobium powder (5wt%), tantalum powder (10wt%), hafnium powder (2wt%) and 80nm carbon powder (3wt%) were mixed evenly by mechanical ball milling to form a mixed powder; the mixed powder was put into a spray gun, the flame flow speed was adjusted to 800m / s, the mixed powder spray speed was 500m / s, and spraying was carried out for 20min to form a (WMoNbTaHf)Cx (x=1~3wt%) high entropy alloy coating with a thickness of 80μm on the surface of the tungsten oxide layer.

[0033] After spraying, the high entropy alloy coating is cooled. The tungsten oxide layer and the high entropy alloy coating form an anti-ablation composite coating. The properties of the anti-ablation composite coating are shown in Table 1.

[0034] Example 3

[0035] A method for preparing an anti-ablation composite coating on a W-Re alloy surface comprises the following steps:

[0036] The surface of the alloy substrate with a size of φ40×10mm was mechanically polished and cleaned with alcohol; then, the treated alloy substrate was used as the anode and the stainless steel was used as the cathode. The electrodes were placed in a Na2SiO3 electrolyte with a pH of 14, and the electrolyte temperature was adjusted to 45°C, the voltage to 500V, and the current density to 8A / dm 2 The micro-arc oxidation time is 40 minutes, and a tungsten oxide layer with a thickness of 80 μm is formed on the surface of the alloy substrate; the alloy substrate after micro-arc oxidation is taken out from the electrolyte and rinsed with clean water.

[0037] The tungsten oxide layer was polished to a depth of 5 μm, and the polished tungsten oxide layer was wiped with alcohol.

[0038] 80nm tungsten powder (20wt%), molybdenum powder (10wt%), niobium powder (20wt%), tantalum powder (30wt%), hafnium powder (20wt%) and 80nm carbon powder (1wt%) were evenly mixed by mechanical ball milling; the mixed powder was put into a spray gun, the flame flow speed was adjusted to 800m / s, the mixed powder spray speed was 500m / s, and spraying was performed for 16min to form a (WMoNbTaHf)Cx (x=1~3wt%) high entropy alloy coating with a thickness of 60μm on the surface of the tungsten oxide layer.

[0039] After spraying, the high entropy alloy coating is cooled. The tungsten oxide layer and the high entropy alloy coating form an anti-ablation composite coating. The properties of the anti-ablation composite coating are shown in Table 1.

[0040] Example 4

[0041] A method for preparing an anti-ablation composite coating on a W-Re alloy surface comprises the following steps:

[0042] The surface of the alloy substrate with a size of φ30×5mm was mechanically polished and cleaned with alcohol; then, the treated alloy substrate was used as the anode and the stainless steel was used as the cathode. The electrodes were placed in a Na2SiO3 electrolyte with a pH of 14, and the electrolyte temperature was adjusted to 40°C, the voltage to 450V, and the current density to 8A / dm 2 The micro-arc oxidation time is 45 minutes, and a tungsten oxide layer with a thickness of 60 μm is formed on the surface of the alloy substrate; the alloy substrate after micro-arc oxidation is taken out from the electrolyte and rinsed with clean water.

[0043] The tungsten oxide layer was polished to a depth of 5 μm, and the polished tungsten oxide layer was wiped with alcohol.

[0044] 80nm tungsten powder (50wt%), molybdenum powder (30wt%), niobium powder (5wt%), tantalum powder (10wt%), hafnium powder (2wt%) and 80nm carbon powder (3wt%) were mixed evenly by mechanical ball milling to form a mixed powder; the mixed powder was put into a spray gun, the flame flow speed was adjusted to 900m / s, the mixed powder spray speed was adjusted to 600m / s, and spraying was carried out for 10min to form a (WMoNbTaHf)Cx (x=1~3wt%) high entropy alloy coating with a thickness of 50μm on the surface of the tungsten oxide layer.

[0045] After spraying, the high entropy alloy coating is cooled. The tungsten oxide layer and the high entropy alloy coating form an anti-ablation composite coating. The properties of the anti-ablation composite coating are shown in Table 1.

[0046] Example 5

[0047] A method for preparing an anti-ablation composite coating on a W-Re alloy surface comprises the following steps:

[0048] The surface of the alloy substrate with a size of φ30×5mm was mechanically polished and cleaned with alcohol; then, the treated alloy substrate was used as the anode and the stainless steel was used as the cathode. The electrodes were placed in a Na2SiO3 electrolyte with a pH of 13, and the electrolyte temperature was adjusted to 40°C, the voltage to 400V, and the current density to 8A / dm 2 The micro-arc oxidation time is 40 minutes, and a tungsten oxide layer with a thickness of 50 μm is formed on the surface of the alloy substrate; the alloy substrate after micro-arc oxidation is taken out from the electrolyte and rinsed with clean water.

[0049] The tungsten oxide layer was polished to a depth of 5 μm, and the polished tungsten oxide layer was wiped with alcohol.

[0050] 80nm tungsten powder (50wt%), molybdenum powder (30wt%), niobium powder (5wt%), tantalum powder (10wt%), hafnium powder (2wt%) and 80nm carbon powder (3wt%) were mixed evenly by mechanical ball milling to form a mixed powder; the mixed powder was put into a spray gun, the flame flow speed was adjusted to 900m / s, the mixed powder spray speed was adjusted to 600m / s, and spraying was carried out for 20min to form a (WMoNbTaHf)Cx (x=1~3wt%) high entropy alloy coating with a thickness of 60μm on the surface of the tungsten oxide layer.

[0051] After spraying, the high entropy alloy coating is cooled. The tungsten oxide layer and the high entropy alloy coating form an anti-ablation composite coating. The properties of the anti-ablation composite coating are shown in Table 1.

[0052] Table 1 Performance parameters of the anti-ablation composite coating in Examples 2-5

[0053] Comparative Example

[0054] The surface of the alloy substrate with a size of φ30×5mm was mechanically polished and cleaned with alcohol; then, the treated alloy substrate was used as the anode and the stainless steel was used as the cathode. The electrodes were placed in a Na2SiO3 electrolyte with a pH of 13, and the electrolyte temperature was adjusted to 40°C, the voltage to 400V, and the current density to 8A / dm 2 The micro-arc oxidation time is 40 minutes, and a tungsten oxide layer with a thickness of 50 μm is formed on the surface of the alloy substrate; the alloy substrate after micro-arc oxidation is taken out from the electrolyte and rinsed with clean water, and the bonding strength of the anti-ablation composite coating is 43 MPa. It is easy to peel off under the scouring of high-speed airflow, showing brittleness.

[0055] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A W-Re alloy having an anti-ablation composite coating on the surface, characterized in that: A tungsten oxide layer and a high entropy alloy coating are sequentially arranged on the surface of the alloy substrate from the inside to the outside. The high entropy alloy coating is (WMoNbTaHf)Cx, and x=1-3wt%.

2. The W-Re alloy having an anti-ablation composite coating on the surface as claimed in claim 1, characterized in that: The thickness of the tungsten oxide layer is 30-80 μm.

3. The W-Re alloy having an anti-ablation composite coating on the surface as claimed in claim 1, characterized in that: The thickness of the high entropy alloy coating is 50-100 μm.

4. A method for preparing an anti-ablation composite coating on a W-Re alloy surface, characterized in that: The surface of the alloy substrate is treated and a tungsten oxide layer is formed on the surface by micro-arc oxidation; Polishing the tungsten oxide layer; 20wt%-50wt% of tungsten powder, 10wt%-30wt% of molybdenum powder, 5wt%-20wt% of niobium powder, 10wt%-30wt% of tantalum powder, 1wt%-20wt% of hafnium powder and 1wt%-3wt% of carbon powder are mixed to obtain a uniform powder, and the mixed powder is sprayed on the surface of the tungsten oxide layer to form a high entropy alloy coating.

5. The method for preparing an anti-ablation composite coating on a W-Re alloy surface as claimed in claim 4, characterized in that: The process of forming a tungsten oxide layer on the surface of the W-Re alloy by micro-arc oxidation is to use the W-Re alloy as the anode and stainless steel as the cathode, and place the W-Re alloy and stainless steel in a Na2SiO3 electrolyte at a temperature of 5-80°C for micro-arc oxidation. The process parameters of micro-arc oxidation are: voltage 400-600V, current density 1-10A / dm 2 .

6. The method for preparing an anti-ablation composite coating on a W-Re alloy surface as claimed in claim 5, characterized in that: The pH of the Na2SiO3 electrolyte is 12-14.

7. The method for preparing an anti-ablation composite coating on a W-Re alloy surface as claimed in claim 4, characterized in that: The grinding depth of the tungsten oxide layer is 5-10μm.

8. The method for preparing an ablation-resistant composite coating on a W-Re alloy surface as claimed in claim 4, characterized in that: The particle size of the tungsten, molybdenum, niobium, tantalum and hafnium powders is 50-100 nm, and the particle size of the carbon powder is 100-200 nm.

9. The method for preparing an anti-ablation composite coating on a W-Re alloy surface as claimed in claim 4, characterized in that: The mixed powder is sprayed on the surface of the tungsten oxide layer by high-speed plasma thermal spraying.

10. The method for preparing an anti-ablation composite coating on a W-Re alloy surface as claimed in claim 9, characterized in that: The process parameters of high-speed plasma thermal spraying are: flame velocity is 500-1200m / s, and mixed powder spraying velocity is 200-700m / s.

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