A method for the production of a Pt+NiRE-gamma / gamma' coating for the protection of nickel-based superalloys and the inhibition of the formation of diffusion pores

Abstract

The present application belongs to the technical field of high-temperature alloy protective coating, and relates to a preparation method of a Pt+NiRE-gamma / gamma' coating for protecting nickel-based high-temperature alloy and inhibiting the formation of diffusion holes. The elements of the Pt+NiRE-gamma / gamma' coating include Ni, Al, Pt and RE; wherein, Ni and Al form gamma'-Ni3Al and gamma-Ni phases, and Pt and RE elements are solid-solved into the gamma'-Ni3Al and gamma-Ni phases. The present application takes the gamma / gamma' phase similar to the main phase of the nickel-based high-temperature alloy as the main phase, and modifies the coating by means of Pt and active element RE. The coating is prepared by means of composite plating of Ni+RE and electroplating of Pt and then diffusion annealing, so that the formation of diffusion holes in the coating is inhibited, and the mechanical properties of the coating and the alloy are protected.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-temperature alloy protective coating, in particular to a preparation method of Pt+NiRE-γ / γ' coating for protecting nickel-based high-temperature alloy and inhibiting the formation of diffusion pores. BACKGROUND

[0002] Nickel-based high-temperature alloy is a kind of material with excellent performance under extreme conditions such as high temperature and high pressure, and is widely used in the fields of aviation and energy. Nickel-based high-temperature alloy exhibits excellent mechanical properties at high temperature, but due to the continuous reduction of the content of high-temperature corrosion-resistant elements (Al and Cr) in the alloy during the iterative improvement process, it is difficult to form a protective oxide film (such as α-Al2O3) on the surface of the alloy in harsh service environments, so the high-temperature oxidation resistance and hot corrosion resistance of the alloy are generally provided by the high-temperature protective coating applied on the surface. Adding Pt group elements (such as Pt, Pd) or some active elements (REs, such as Hf, Ce, Y, etc.) in the aluminide coating can change the oxidation mechanism of the coating.

[0003] Pt element as a modification element has been widely used in high-temperature protective coating at present, and its role in high-temperature oxidation resistance mainly includes the following points: 1. Pt element can inhibit the growth of the gap between the oxidation film and the metal interface, which is beneficial to improve the bonding strength between the Al2O3 film and the coating; 2. Pt element can effectively promote the formation of single α-Al2O3 oxidation film, and the affinity between Pt and Al element is strong, which is beneficial to the uphill diffusion of Al element in the matrix and helps to form a continuous and dense alumina protective film on the surface; 3. The presence of Pt element can reduce the critical aluminum content required for the formation of α-Al2O3 oxidation film, which can ensure the continuous formation of alumina protective film; 4. The presence of Pt element can inhibit the outward diffusion of refractory alloy elements (such as W, Mo, etc.), and reduce the harm of S element.

[0004] The addition of active elements (REs, such as Hf, Ce, Y, etc.) in the high-temperature protective coating can improve the adhesion of the oxidation film generated during high-temperature oxidation. Current research believes that the mechanism of active elements improving the adhesion of Al2O3 film during high-temperature oxidation mainly includes the following aspects: 1. Inhibiting the generation and growth of pores at the interface between the oxidation film and the alloy matrix; 2. Generating active element oxides at the interface between the oxidation film and the alloy matrix, increasing the contact area between the oxidation film and the alloy matrix; 3. Relieving the wrinkling phenomenon of the oxidation film; 4. Directly participating in the bonding at the interface between the oxidation film and the alloy matrix, improving the bonding ability of the interface.

[0005] Pt diffusion γ / γ' coating is a kind of coating applied to the surface protection of nickel-based superalloy, which can effectively improve the high-temperature oxidation resistance and corrosion resistance of the alloy. Pt diffusion γ / γ' coating can be prepared by electroplating 5-8 μm of Pt and then performing diffusion treatment. Compared with β-(Ni, Pt) Al coating, γ / γ' coating has higher creep strength, better compatibility between the coating and the high-temperature alloy substrate, and lower manufacturing cost, etc. However, there is still a common problem in the preparation process of this kind of coating: when the Pt layer is electroplated on the surface of the nickel-based superalloy and then vacuum annealed, due to the different interdiffusion rates between the elements in the alloy substrate and the Pt elements in the plating layer, a large number of pores are generated in the coating after vacuum annealing. When the high-temperature alloy workpiece is subjected to cyclic loading stress, the pores in the coating will become fatigue crack sources, greatly shortening the service life of the coating. SUMMARY

[0006] The purpose of the present application is to provide a preparation method of Pt+NiRE-γ / γ' coating for the protection of nickel-based superalloy and the inhibition of the formation of diffusion pores. By improving the Pt diffusion γ / γ' coating, a Ni+RE layer is first electroplated, then a Pt layer is electroplated, and then vacuum diffusion annealing is performed. The existence of the Ni+RE layer solves the problem of mismatched interdiffusion between the alloy and the plating layer, and inhibits the formation of diffusion pores, thereby solving the problems existing in the prior art.

[0007] To achieve the above purpose, the present application provides the following solutions:

[0008] One of the technical solutions of the present application provides a Pt+NiRE-γ / γ' coating suitable for the protection of nickel-based superalloy, which contains elements of Ni, Al, Pt and RE; wherein Ni and Al form γ'-Ni3Al and γ-Ni phases, and Pt and RE elements are solid-solved into the γ'-Ni3Al and γ-Ni phases.

[0009] Further, the mass ratio of Ni, Al, Pt and RE is 60-70:20-25:8-11:1-4

[0010] Further, the RE includes Hf and / or Y.

[0011] The second technical solution of the present application provides a preparation method of the above-mentioned Pt+NiRE-γ / γ' coating suitable for the protection of nickel-based superalloy, which comprises the following steps:

[0012] After pretreatment, the sample is placed in a nickel plating suspension liquid containing RE powder, and a Ni+RE layer is obtained by first electroplating to obtain a first electroplated sample;

[0013] placing the first electroplating sample in a Pt plating solution to obtain a Pt layer by second electroplating, thereby obtaining a second electroplating sample;

[0014] vacuum diffusion annealing the second electroplating sample to obtain the Pt+NiRE-γ / γ' coating.

[0015] The sample is an aluminum-containing nickel-based high-temperature alloy.

[0016] Further, the aluminum-containing nickel-based high-temperature alloy is an aluminum-containing nickel-based single-crystal alloy.

[0017] Further, the pretreatment step comprises sequentially polishing, sandblasting, ultrasonic cleaning, electrochemical degreasing and activation treatment of the sample.

[0018] Preferably, the polishing is sequentially performed by using SiC sandpaper with a mesh size of 400, 1000 and 2000.

[0019] When polishing, the edges of the sample are polished to be chamfered to prevent stress concentration at the edges from causing cracking during coating preparation or premature peeling of the surface oxide film during sample oxidation.

[0020] Preferably, the sandblasting is wet sandblasting using 150-mesh alumina pills.

[0021] Preferably, the ultrasonic cleaning is sequentially performed in deionized water, alcohol and acetone for 20 minutes each.

[0022] Preferably, the electrochemical degreasing step is performed in a sodium hydroxide solution with a concentration of 5-15 g / L, with the sample as the cathode and a stainless steel plate as the anode, at a current density of 2-15 A / dm 2 for 1-10 minutes.

[0023] Preferably, the activation treatment step is placing the sample in an activation solution for 0.5-5 minutes; the activation solution is an aqueous solution of hydrochloric acid and phosphoric acid, wherein the concentration of hydrochloric acid in the activation solution is 10-30 vol.%, and the concentration of phosphoric acid is 5-25 vol.%.

[0024] Further, the nickel plating suspension containing RE powder comprises 150-180 g / L of NiSO4·6H2O, 8-15 g / L of NaCl, 30-60 g / L of H3BO3, 110-130 g / L of Na2SO4, 0.1-0.2 g / L of sodium dodecyl sulfate and 0-20 g / L of RE, and the content of RE is not 0.

[0025] The solvent of the nickel plating suspension mixed with RE powder is water, and the pH is 4.0-6.0.

[0026] Further, the first electroplating has an electroplating temperature of 30-40℃ and a current density of 4-12 mA / cm 2 for 0.5-2 h.

[0027] Further, the Ni+RE layer has a thickness of 5-8 μm.

[0028] Further, the Pt plating solution comprises 5-15 g / L of dichloro diammine platinum and 5-15 g / L of sodium nitrite.

[0029] The solvent of the Pt plating solution is water, and ammonia is used to adjust the pH value to 8.0-10.0.

[0030] Further, the second electroplating has an electroplating temperature of 70-80℃ and a current density of 4-6 mA / cm 2 for 2-4 h.

[0031] Further, the Pt layer has a thickness of 5-8 μm.

[0032] Further, the vacuum diffusion annealing process comprises the following steps: vacuum sealing the second electroplating sample, then heating to 480-500℃ at a heating rate of 5-10℃ / min, holding for 2-2.5 h, then heating to 1080-1100℃ at a heating rate of 5-10℃ / min, holding for 3.5-4 h, and cooling to room temperature in the furnace.

[0033] Further, the Pt+NiRE-γ / γ' coating layer has a thickness of 10-30 μm.

[0034] During the vacuum diffusion annealing process, the Ni+RE layer and the Pt layer interdiffuse with the alloy to form the Pt+NiRE-γ / γ' coating layer, and the thickness is increased compared to before the vacuum diffusion annealing.

[0035] The third technical scheme of the present application provides a Pt+NiRE-γ / γ' coating layer for nickel-based superalloy protection.

[0036] Further, the application in nickel-based superalloy protection comprises that the Pt+NiRE-γ / γ' coating layer is used as a high-temperature oxidation / corrosion resistant protective coating or a thermal barrier coating bonding layer of the nickel-based superalloy.

[0037] The high-temperature oxidation / corrosion resistant protective coating refers to a coating that has both high-temperature oxidation resistance and corrosion resistance.

[0038] The fourth technical scheme of the present application provides a method for inhibiting the formation of diffusion pores of a Pt diffusion gamma / gamma' coating, which comprises the following steps: firstly, electroplating a Ni+RE layer on the surface of a nickel-based high-temperature alloy; secondly, electroplating a Pt layer; and thirdly, performing vacuum diffusion annealing.

[0039] The present application discloses the following technical effects:

[0040] The present application takes the gamma / gamma' phase similar to the main phase of the nickel-based high-temperature alloy as the main phase, and modifies the coating by means of Pt and active element RE. The coating is prepared by means of composite plating of Ni+RE and electroplating of Pt and then diffusion annealing, so as to inhibit the formation of diffusion pores in the coating and protect the mechanical properties of the coating and the alloy. The modification of the Pt element can promote the formation of a protective Al2O3 film on the surface of the coating, inhibit the S segregation behavior at the interface of the coating, and enhance the oxidation resistance of the coating. The addition of the active element can pin the oxide film and inhibit the aggregation of pores at the interface of the oxide film, so as to enhance the bonding force between the oxide film and the coating. Therefore, the Pt+NiRE-gamma / gamma' coating has excellent high-temperature oxidation resistance and corrosion resistance at high temperatures. On the other hand, since the phase of the coating is similar to the phase in the alloy, mutual diffusion between the coating and the alloy can be avoided during the service of the coating, and the formation of TCP phase is inhibited, so as to maintain the stability of the alloy structure.

[0041] The present application applies the electroplating method to apply the Ni and Pt coatings on the surface of the substrate, and the preparation cost is low. The structure of the two plating layers and the diffusion annealing can inhibit the formation of diffusion pores in the coating. The Pt and active element are used to modify the coating, so as to enhance the ability of the coating to form a protective oxide film and improve the anti-spalling performance of the oxide film. BRIEF DESCRIPTION OF DRAWINGS

[0042] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0043] Figure 1 The SEM images of the surface of the plating layer before annealing treatment for Examples 1-2 and Comparative Examples 1-2 are shown in (a) for Comparative Example 1, (b) for Comparative Example 2, (c) for Example 1, and (d) for Example 2.

[0044] Figure 2 The morphology images of the cross section of the plating layer before annealing treatment for Examples 1-2 and Comparative Examples 1-2 are shown in (a) for Comparative Example 1, (b) for Comparative Example 2, (c) for Example 1, and (d) for Example 2.

[0045] Figure 3 Cross-sectional morphology of the coating after annealing for Examples 1-2 and Comparative Examples 1-2, where (a) is Comparative Example 1, (b) is Comparative Example 2, (c) is Example 1, and (d) is Example 2;

[0046] Figure 4 XRD pattern of the coating after annealing for Examples 1-2 and Comparative Examples 1-2, where (a) is Comparative Example 1, (b) is Comparative Example 2, (c) is Example 1, and (d) is Example 2;

[0047] Figure 5 Cross-sectional morphology of the sample after annealing for Examples 1-2 and Comparative Example 1 after 100 h of cyclic oxidation at 1000°C, where (a) is Comparative Example 1, (b) is Example 1, and (c) is Example 2;

[0048] Figure 6 XRD pattern of the coating after annealing for Examples 1-2 and Comparative Example 1 after 100 h of cyclic oxidation at 1000°C, where (a) is Comparative Example 1, (b) is Example 1, and (c) is Example 2;

[0049] Figure 7 Coating mass gain plot for the sample after annealing for Examples 1-2 and Comparative Example 1 after 100 h of cyclic oxidation at 1000°C. DETAILED DESCRIPTION

[0050] The following detailed description of various example embodiments of the application will not be considered to limit the application to these embodiments only, but rather to provide a more thorough description of the various aspects, features and embodiments of the application.

[0051] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. Additionally, the use of the term "about" in relation to a value or a range of values is intended to include each and every value falling within the range and each and every value falling within the range. The upper and lower limits of these smaller ranges can independently be included or excluded in the stated ranges. It is also to be understood that the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0052] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although preferred methods and materials are described, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application. All documents mentioned herein are incorporated by reference to disclose and describe the methods and / or materials in connection with which the documents are cited. In case of conflict between the present specification and any document incorporated by reference, the present specification will control.

[0053] Many modifications and variations of the specific embodiments of the application can be made without departing from the scope or spirit of the application, which will be apparent to those skilled in the art. Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application. The specification and examples are illustrative only.

[0054] As used herein, the terms "comprise", "comprising", "include", "including", "have" and "having" and the like are open-ended, and specifically mean "including, but not limited to".

[0055] The raw materials and reagents used in the specific embodiments of the application are all commercially available products, wherein the second generation nickel-based single crystal superalloy N5 is provided by the Institute of Metal Research, Chinese Academy of Sciences, and the brand is N5 alloy.

[0056] Example 1

[0057] Preparation of Pt+NiHf-γ / γ' coating:

[0058] S1, the substrate sample used is the second generation nickel-based single crystal superalloy N5, the sample size is Φ16mmx2.5mm, and the substrate sample is sequentially subjected to polishing, sand blasting treatment, ultrasonic cleaning, electrochemical degreasing and activation treatment to obtain a pretreated sample;

[0059] Polishing is to polish the substrate sample with SiC sandpaper of 400, 1000 and 2000 mesh in sequence; sand blasting treatment is to wet sand blast the substrate sample with 150 mesh alumina pills; ultrasonic cleaning of the substrate sample is to sequentially ultrasonically clean the substrate sample in deionized water, alcohol and acetone for 20 min; electrochemical degreasing is to electrochemically degrease the substrate sample in a sodium hydroxide solution with a concentration of 7g / L, with the substrate sample as the cathode and a stainless steel plate as the anode, at a current density of 8A / dm 2 2 for 5min; and the activation treatment is to put the substrate sample into an activation solution for 2min; the activation solution is an aqueous solution of hydrochloric acid and phosphoric acid, wherein the concentration of hydrochloric acid in the activation solution is 15vol.%, and the concentration of phosphoric acid is 15vol.%.

[0060] S2, electroplating a Ni+Hf layer, the composition of the electroplating solution is NiSO4·6H2O 152g / L, NaCl 14g / L, H3BO3 37g / L, Na2SO4 111g / L, sodium dodecyl sulfate 0.2g / L, Hf 20g / L, and the balance is deionized water; the pH value of the electroplating solution is adjusted to 5, the pretreated sample is electroplated using an alternating current power source, the electroplating is carried out in a magnetic stirrer, the stirring speed is 5r / min, the whole electroplating process is carried out under constant temperature, the temperature is controlled at 40℃ during electroplating, and the current density is controlled at 10mA / cm 2, the whole electroplating process keeps the pH value of the electroplating solution in the range of 8-10, the thickness of the electroplated Pt layer is 7.9 μm, and a second electroplated sample is obtained;

[0061] S3, electroplating a Pt layer, the electroplating solution comprises 5.5 g / L of dinitrosodiaminoplatinum and 14 g / L of sodium nitrite, and the rest is deionized water, ammonia is used to adjust the pH value of the electroplating solution to 9, the first electroplated sample is electroplated by using an alternating current power source, the electroplating is carried out in a magnetic stirrer, the stirring speed is 2 r / min, the whole electroplating process is carried out at a constant temperature, the temperature is controlled at 80 ℃ during electroplating, and the current density is controlled at 5 mA / cm 2

[0062] S4, vacuum sealing the second electroplated sample, and performing annealing treatment in a muffle furnace: the temperature is raised at a speed of 10 ℃ / min, the temperature is raised to 500 ℃ first, and then the temperature is raised to 1080 ℃ at a speed of 5 ℃ / min, the temperature is kept for 4 h, the furnace is cooled to room temperature, and a sample with a Pt+NiHf-γ / γ' coating is obtained.

[0063] Example 2

[0064] Preparation of a Pt+NiY-γ / γ' coating:

[0065] S1, the same as step S1 in Example 1, and a pretreated sample is obtained;

[0066] S2, electroplating a Ni+Y layer, the electroplating solution comprises 170 g / L of NiSO4·6H2O, 15 g / L of NaCl, 40 g / L of H3BO3, 130 g / L of Na2SO4, 0.2 g / L of sodium dodecyl sulfate and 20 g / L of Y, and the rest is deionized water; the pH value of the electroplating solution is adjusted to 5, the pretreated sample is electroplated by using an alternating current power source, the electroplating is carried out in a magnetic stirrer, the stirring speed is 5 r / min, the whole electroplating process is carried out at a constant temperature, the temperature is controlled at 40 ℃ during electroplating, and the current density is controlled at 10 mA / cm 2 , the whole electroplating process keeps the pH value of the electroplating solution in the range of 8-10, the thickness of the electroplated Pt layer is 7.9 μm, and a second electroplated sample is obtained;

[0067] S3, electroplating a Pt layer, the electroplating solution comprises 5.5 g / L of dinitrosodiaminoplatinum and 14 g / L of sodium nitrite, and the rest is deionized water, ammonia is used to adjust the pH value of the electroplating solution to 9, the first electroplated sample is electroplated by using an alternating current power source, the electroplating is carried out in a magnetic stirrer, the stirring speed is 2 r / min, the whole electroplating process is carried out at a constant temperature, the temperature is controlled at 80 ℃ during electroplating, and the current density is controlled at 5 mA / cm​2 The pH value of the plating solution was kept in the range of 8-10 during the whole plating process, and the thickness of the Pt layer was 7.9 μm, to obtain a second plating sample;

[0068] S4, vacuum sealing tube was performed on the second plating sample, and the sample was put into a muffle furnace for annealing treatment: the temperature was raised to 500 ℃ at a rate of 10 ℃ / min, and then the temperature was kept for 2 h, then the temperature was raised to 1080 ℃ at a rate of 5 ℃ / min, and then the temperature was kept for 4 h, and then the furnace was cooled to room temperature, to obtain a sample with a Pt+NiY-γ / γ' coating.

[0069] Comparative Example 1

[0070] Preparation of a conventional Pt+Hf-γ / γ' coating:

[0071] S1, the substrate sample used was a second-generation nickel-based single crystal superalloy N5, and the sample size was Φ16 mm x 2.5 mm. The substrate sample was sequentially polished, sandblasted, ultrasonically cleaned, electrochemically degreased, and activated to obtain a pretreated sample;

[0072] The polishing was sequentially performed on the substrate sample using SiC sandpaper with a mesh size of 400, 1000, and 2000. The sandblasting treatment was wet sandblasting treatment performed on the substrate sample using 150 mesh alumina balls. The substrate sample was ultrasonically cleaned in deionized water, alcohol, and acetone for 20 min, respectively. The electrochemical degreasing was performed on the substrate sample in a sodium hydroxide solution with a concentration of 7 g / L, with the substrate sample as the cathode and a stainless steel plate as the anode, at a current density of 8 A / dm 2 The treatment was performed for 5 min. The activation treatment was performed by putting the substrate sample into an activation solution for 2 min. The activation solution was an aqueous solution of hydrochloric acid and phosphoric acid, wherein the concentration of hydrochloric acid in the activation solution was 15 vol.%, and the concentration of phosphoric acid was 15 vol.%;

[0073] S2, a Pt+Hf layer was plated, and the composition of the plating solution was 9 g / L of dinitrosodiaminoplatinum, 10 g / L of sodium nitrite, and 20 g / L of Hf, with the balance being water. The pH value of the plating solution was adjusted to 9 using ammonia water. The pretreated sample was plated using an alternating current power source, and the plating was performed in a magnetic stirrer, with a stirring speed of 2 r / min. The whole plating process was performed at a constant temperature, and the temperature was controlled at 80 ℃ during plating, and the current density was controlled at 5 mA / cm 2 The pH value of the plating solution was kept in the range of 8-10 during the whole plating process, and the thickness of the Pt+Hf layer was 7.5 μm, to obtain a plating sample;

[0074] S3, vacuum sealing the electroplated sample and placing it into a muffle furnace for annealing treatment, the heating rate is 10℃ / min, first heating to 500℃ for 2h, then heating to 1080℃ at a rate of 5℃ / min, and keeping the temperature for 4h, and then cooling to room temperature in the furnace, to obtain a sample with Pt+Hf-γ / γ' coating.

[0075] Comparative Example 2

[0076] Preparation of Pt+Ni-γ / γ' coating:

[0077] S1, the substrate sample used is a second-generation nickel-based single crystal superalloy N5, the sample size is Φ16mm×2.5mm, and the substrate sample is sequentially subjected to polishing, sand blasting treatment, ultrasonic cleaning, electrochemical degreasing and activation treatment to obtain a pretreated sample;

[0078] The polishing is sequentially polishing the substrate sample with SiC sandpaper of 400, 1000 and 2000 mesh; the sand blasting treatment is wet sand blasting treatment of the substrate sample with 150 mesh alumina balls; the ultrasonic cleaning of the substrate sample is sequentially ultrasonic cleaning in deionized water, alcohol and acetone for 20min; the electrochemical degreasing is electrochemical degreasing of the substrate sample in a sodium hydroxide solution with a concentration of 7g / L, taking the substrate sample as the cathode and a stainless steel plate as the anode, and the current density is 8A / dm 2 2 for 5min; the activation treatment is placing the substrate sample into an activation solution for 2min; the activation solution is an aqueous solution of hydrochloric acid and phosphoric acid, wherein the concentration of hydrochloric acid in the activation solution is 15vol.%, and the concentration of phosphoric acid is 15vol.%;

[0079] S2, electroplating a Ni layer, the electroplating solution composition is NiSO4·6H2O 150g / L, NaCl 10g / L, H3BO3 32g / L, Na2SO4 124g / L, sodium dodecyl sulfate 0.15g / L, and the balance is deionized water; the pH value of the electroplating solution is adjusted to 5, and the pretreated sample is electroplated by using an alternating current power source, the electroplating is carried out in a magnetic stirrer, and the stirring speed is 5r / min; the whole electroplating process is carried out at constant temperature, the temperature is controlled at 40℃ during electroplating, and the current density is controlled at 10mA / cm 2 2, and the pH value of the electroplating solution is maintained within the range of 5-7 during the whole electroplating process, the thickness of the electroplated Ni layer is 8μm, and a first electroplated sample is obtained;

[0080] S3, electroplating Pt layer, the composition of the electroplating solution is 7.5 g / L of dinitrosoplatinum diammine and 11 g / L of sodium nitrite, the rest is deionized water, the pH value of the electroplating solution is adjusted to 9 with ammonia water, then the first electroplated sample is electroplated by using alternating current power, the electroplating is carried out in a magnetic stirrer, the stirring speed is 2 r / min, the whole electroplating process is carried out at constant temperature, the temperature is controlled at 80℃ during electroplating, the current density is controlled at 5 mA / cm 2 , the pH value of the electroplating solution is kept in the range of 8-10 during the whole electroplating process, the thickness of the electroplated Pt layer is 8.2 μm, and the second electroplated sample is obtained;

[0081] S4, vacuum sealing the second electroplated sample and placing it into a muffle furnace for annealing treatment, the heating rate is 10℃ / min, first heating to 500℃ and keeping for 2 h, then heating to 1080℃ at a rate of 5℃ / min, keeping for 4 h, and cooling to room temperature with the furnace, to obtain a sample with Pt+Ni-γ / γ' coating.

[0082] Test examples

[0083] Figure 1 SEM images of the surface of the coating before annealing treatment for Examples 1-2 and Comparative Examples 1-2, wherein (a) is Comparative Example 1, (b) is Comparative Example 2, (c) is Example 1, and (d) is Example 2. It can be seen from Figure 1 that the typical spherical protrusion morphology in the comparative examples and examples proves that the Pt layer is successfully electroplated onto the surface, the modification of the Pt element can promote the formation of a protective Al2O3 film on the surface of the coating and inhibit the S segregation behavior at the coating interface, thereby enhancing the oxidation resistance of the coating.

[0084] Figure 2 Morphology images of the cross section of the coating before annealing treatment for Examples 1-2 and Comparative Examples 1-2, wherein (a) is Comparative Example 1, (b) is Comparative Example 2, (c) is Example 1, and (d) is Example 2. It can be seen from Figure 2 that the Pt layer of the comparative examples and examples is closely attached to the coating.

[0085] Figure 3 Cross-sectional morphology images of the coating after annealing treatment for Examples 1-2 and Comparative Examples 1-2, wherein (a) is Comparative Example 1, (b) is Comparative Example 2, (c) is Example 1, and (d) is Example 2. It can be seen from Figure 3 that after comparing (b), (c) and (d) with (a), it can be found that the cross-sectional morphology of (a) contains a large number of diffusion pores, and the cross-sectional morphology of (b), (c) and (d) contains much fewer diffusion pores.

[0086] Figure 4XRD patterns of the coating of the annealed samples of Examples 1-2 and Comparative Examples 1-2, wherein (a) is Comparative Example 1, (b) is Comparative Example 2, (c) is Example 1, and (d) is Example 2. Figure 4 It can be seen that the Comparative Examples and the Examples are typical γ'-Ni3Al phases, the coating phase is similar to the phase in the alloy, the mutual diffusion between the coating and the alloy can be avoided during the service of the coating, the formation of TCP phase is inhibited, and the effect of maintaining the stability of the alloy organization is achieved.

[0087] Figure 5 Cross-sectional morphology of the coating of the annealed samples of Examples 1-2 and Comparative Example 1 after cyclic oxidation at 1000℃ for 100h, wherein (a) is Comparative Example 1, (b) is Example 1, and (c) is Example 2. Figure 5 It can be seen that no holes are generated at the interface of the coating of Examples 1-2, and the generation of holes in the coating is obviously inhibited, which makes the bonding force between the coating and the substrate more excellent.

[0088] Figure 6 XRD patterns of the coating of the annealed samples of Examples 1-2 and Comparative Example 1 after cyclic oxidation at 1000℃ for 100h, wherein (a) is Comparative Example 1, (b) is Example 1, and (c) is Example 2. Figure 6 It can be seen that Al2O3 protective film is generated in the three, and HfO2 is also generated in Comparative Example 1.

[0089] Figure 7 Mass gain curve of the coating of the annealed samples of Examples 1-2 and Comparative Example 1 after cyclic oxidation at 1000℃ for 100h (Pt+HF is Comparative Example 1, Ni+Y-Pt is Example 2, and Ni+HF-Pt is Example 1). Figure 7 It can be seen that the mass gain of Examples 1 and 2 is lower than that of Comparative Example 1, and the mass gain curve of Examples 1 and 2 enters the stable oxidation stage more quickly than that of Comparative Example 1, which provides a stable oxidation film earlier and has more excellent oxidation resistance. It can be seen that the improved method used in the Pt+NiRE-γ / γ' coating of the present application has a simpler preparation process and saves cost compared with the existing technology, and can obviously inhibit the generation of diffusion holes in the coating.

[0090] The above-described examples are only used to describe the preferred modes of the present application, and do not limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements of the technical solutions of the present application made by those skilled in the art shall fall within the protection scope determined by the claims of the present application.

Claims

1. A Pt+NiRE-γ / γ' coating suitable for the protection of nickel-based superalloys, characterized in that, The Pt+NiRE-γ / γ' coating comprises Ni, Al, Pt, and RE; wherein Ni and Al constitute the γ'-Ni3Al and γ-Ni phases, and Pt and RE elements are dissolved into the γ'-Ni3Al and γ-Ni phases. The RE is Hf and / or Y; The mass ratio of Ni, Al, Pt and RE is 60~70:20~25:8~11:1~4.

2. A method for preparing a Pt+NiRE-γ / γ' coating as described in claim 1, characterized in that the step... include: After pretreatment, the sample was placed in a nickel plating suspension containing RE powder and a Ni+RE layer was obtained by the first electroplating, thus obtaining the first electroplated sample. The first electroplating sample was placed in a Pt plating solution and a Pt layer was obtained by a second electroplating, thus obtaining the second electroplating sample. The second electroplated sample was subjected to vacuum diffusion annealing to obtain the Pt+NiRE-γ / γ' coating. The sample is an aluminum-containing nickel-based high-temperature alloy; The nickel-plated suspension liquid containing RE powder comprises 150-180 g / L of NiSO4·6H2O, 8-15 g / L of NaCl, 30-60 g / L of H3BO3, 110-130 g / L of Na2SO4, 0.1-0.2 g / L of sodium dodecyl sulfate and 0-20 g / L of RE, and the content of RE is not 0; the plating temperature of the first electroplating is 30-40 ℃, the current density is 4-12 mA / cm 2 , and the time is 0.5 h-2 h; the thickness of the Ni+RE layer is 5-8 μm. The vacuum diffusion annealing process is as follows: the second electroplated sample is vacuum sealed, then heated to 480-500℃ at a heating rate of 5-10℃ / min, held for 2-2.5h, then heated to 1080-1100℃ at a heating rate of 5-10℃ / min, held for 3.5-4h, and then cooled to room temperature in the furnace.

3. The preparation method according to claim 2, characterized in that, The pretreatment steps include: grinding, sandblasting, ultrasonic cleaning, electrochemical degreasing, and activation treatment of the sample in sequence.

4. The preparation method according to claim 2, characterized in that, The Pt plating solution comprises 5-15 g / L of dinitrosodiammineplatinum and 5-15 g / L of sodium nitrite; the electroplating temperature for the second electroplating is 70-80°C, and the current density is 4-6 mA / cm². 2 The time is 2h~4h; the thickness of the Pt layer is 5~8μm.

5. The application of the Pt+NiRE-γ / γ' coating as described in claim 1 in the protection of nickel-based superalloys.

6. A method for suppressing the formation of diffusion pores in a Pt diffusion γ / γ' coating, characterized in that the steps include... include: After pretreatment, the sample was placed in a nickel plating suspension containing RE powder and a Ni+RE layer was obtained by the first electroplating to obtain the first electroplated sample. The first electroplating sample was placed in a Pt plating solution and a Pt layer was obtained by a second electroplating, thus obtaining the second electroplating sample. The second electroplated sample was subjected to vacuum diffusion annealing to obtain a Pt+NiRE-γ / γ' coating; The sample is an aluminum-containing nickel-based high-temperature alloy; The nickel plating suspension containing RE powder comprises: 150-180 g / L NiSO4·6H2O, 8-15 g / L NaCl, 30-60 g / L H3BO3, 110-130 g / L Na2SO4, 0.1-0.2 g / L sodium dodecyl sulfate, and 0-20 g / L RE, wherein the RE content is not zero; the electroplating temperature for the first electroplating is 30-40℃, and the current density is 4-12 mA / cm². 2 The time is 0.5h~2h; the thickness of the Ni+RE layer is 5~8μm; The vacuum diffusion annealing process is as follows: the second electroplated sample is vacuum sealed, then heated to 480-500℃ at a heating rate of 5-10℃ / min, held for 2-2.5h, then heated to 1080-1100℃ at a heating rate of 5-10℃ / min, held for 3.5-4h, and then cooled to room temperature in the furnace. The RE is Hf and / or Y.

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