A coating that does not form acicular phases at the interface with nickel-based alloys and a method for producing it

Abstract

The present application relates to high temperature protective coating technical field, specifically to a coating which does not form needle-shaped phase with nickel-based alloy interface and a preparation method. The coating is composed of carbon interstitial nickel-based, cobalt-based or nickel-cobalt-based alloy and dispersed nano-carbide particles; the preparation method is prepared by regulating vacuum cathode arc plasma in-situ reaction, and the preparation steps include: ① the substrate is subjected to conventional grinding, polishing and oil removal pretreatment, ② the alloy target material is installed, vacuum is drawn and the substrate is subjected to ion sputtering cleaning, ③ the vacuum arc plasma with the coating target material as the cathode is ignited, ④ the workpiece surface is bombarded and activated by cation with energy of 300eV-1000eV, ⑤ the coating is formed on the workpiece surface by depositing the gas containing carbon elements through plasma activation reaction by regulating the partial pressure. The coating can avoid the precipitation of needle-shaped harmful phase at the interface with nickel-based high-temperature alloy, and the method has the advantages of simple and controllable process, suitable for batch preparation and the like.

Description

Technical Field

[0001] This invention relates to the field of high-temperature protective coating technology, and in particular provides a coating that does not form a needle-like phase at the interface with nickel-based alloys and a method for preparing it. Background Technology

[0002] MCrAlY coating is a third-generation high-temperature protective coating developed in the 1980s. It has good comprehensive performance and can be used as a standalone high-temperature protective coating or as a bonding layer in a thermal barrier coating system. MCrAlY can provide sufficient Al source to form a protective Al2O3 film at the interface with the ceramic insulation layer. When the oxide film on the coating surface remains intact, the consumption of antioxidant elements in the coating is mainly due to interdiffusion between the coating and the substrate. The diffusion of Al elements from the coating into the alloy accelerates the degradation of the coating and reduces the service life of the coating, while also reducing the service life of the substrate alloy. For example, the high-temperature creep life of a fourth-generation single crystal with a (Ni,Pt)Al coating is only 14% of that of the original alloy. Therefore, suppressing interdiffusion between the coating and the alloy is of great significance to improving the coating life. To slow down interdiffusion, there are currently three main methods: (1) diffusion barrier. Currently, diffusion barriers mainly include metallic diffusion barriers represented by Ni-Re [see reference: Guo Hongbo, Li Jingchen, He Jian, Wei Liangliang, Preparation method of dense Re-rich diffusion barrier coating on high temperature alloy surface, patent publication number: CN113789557A], ceramic diffusion barriers represented by CrN [see reference: Geng Shujiang, Zhao Maosen, A conductive composite coating containing CrN diffusion barrier layer and preparation method, patent publication number: CN108588662A], and novel reactive diffusion barriers represented by NiCrO [see reference: Wang Fuhui, Zhu Shenglong, Wang Wen, Yu Ping, Wang Shichen, A high temperature coating containing nickel-chromium-oxygen reactive diffusion barrier layer and preparation method, patent publication number: CN104401089A]. (2) Nanocrystalline coating, so that the composition of the coating is as consistent as possible with the alloy. However, with the development of high temperature alloys, the Al content inside the alloy is generally no more than 8 wt.%. The low Al content cannot maintain the formation of the external Al2O3 film for a long time, and the nanocrystals will grow rapidly during high temperature exposure [see reference: WANG J, CHEN M, YANG L, et al. The effect of yttrium addition on oxidation of a sputtered nanocrystalline coating with moderate amount of tantalumin composition[J]. Applied Surface Science, 2016, 366: 245-53.].(3) Phase equilibrium coatings, but phase equilibrium coatings have the disadvantage of insufficient long-term oxidation resistance [see reference: KAWAGISHI K, SATO A, HARADAH. A concept for the EQ coating systell for nickel-based superalloys[J].The Journal of The Minerals,Metals&Materials Society,2008,60(7):31-5.]. However, the diffusion barriers reported so far still have various problems. Metal diffusion barriers have poor high-temperature stability; ceramic diffusion barriers and active diffusion barriers both have the disadvantage of weak bonding between ceramic and metal interfaces, and are prone to peeling during service. Moreover, all three types of diffusion barriers have the disadvantage of complex preparation processes and the introduction of multiple interfaces. Therefore, it is necessary to develop new high-temperature protective coatings to solve the problem of harmful phases formed by interdiffusion between the coating and the substrate.

[0003] Based on the fact that carbides can exist stably at high temperatures, if some elements in the MCrAlY coating can be carbonized, the dispersed carbide ceramic particles will inhibit the interdiffusion between the coating and the substrate. The preparation of conventional carbide-reinforced metal ceramic coatings requires pretreatment such as mixing, high-temperature sintering and grinding of the original coating materials, and the preparation process is complicated [see references: [1] Yao Hailong, Ji Gangchang, Zhang Mengxian, Chen Qingyu, Wang Hongtao, Bai Xiaobo, a tungsten carbide-chromium carbide-nickel composite powder and its preparation method and metal ceramic coating and its preparation method, patent publication number: CN112795861A; [2] Chen Xiao, Li Chengdi, Xu Shunjian, Zhang Xiaowei, Jian Huihua, Hu Yao, a preparation method of a dual-phase carbide metal ceramic solar selective absorption composite coating, patent publication number: CN109825829A]. This invention employs vacuum physical vapor deposition (VPV) technology, in which some alloying elements are carbonized during the coating preparation process. This achieves the effect of dispersed distribution of nano-carbide particles and interstitial carbon filling, thereby inhibiting the diffusion of alloying elements from the coating into the substrate to form needle-like phases. Vacuum ion plating offers unique advantages such as high deposition efficiency, strong film-substrate adhesion, and simple preparation process, making it the preferred technology for preparing the coating of this invention. Summary of the Invention

[0004] To address the problem of traditional MCrAlY coatings interdiffusion with nickel-based superalloys to form acicular phases, thereby reducing the mechanical properties of single-crystal superalloys, and the complexity of traditional carbide-reinforced cermet preparation processes, this invention provides a coating and preparation method that do not form acicular phases at the interface with nickel-based alloys.

[0005] The technical solution of this invention is as follows:

[0006] A coating that does not form a needle-like phase at the interface with a nickel-based alloy, the coating being composed of carbon-filled nickel-based, cobalt-based, or nickel-cobalt-based alloys and dispersed nano-carbide particles.

[0007] As a preferred technical solution:

[0008] The chemical composition of the coating is: nickel 0-75 wt.%, cobalt 0-75 wt.%, chromium 8 wt.%-32 wt.%, aluminum 6 wt.%-16 wt.%, carbon 0.4 wt.%-3.5 wt.%, and other metal components not exceeding 5 wt.% in total; the other metal components are one or more combinations of rare earth elements, hafnium, zirconium, titanium, silicon, tantalum, rhenium, and ruthenium.

[0009] A further preferred embodiment is that the total mass fraction of nickel and cobalt in the coating is 60 wt.% to 75 wt.%, and the total mass fraction of chromium and aluminum is 20 wt.% to 35 wt.%. Within this preferred composition range, it is possible to ensure that the coating generates an appropriate amount of nano-carbide particles while avoiding the decrease in mechanical properties of the coating caused by the formation of excessive nano-carbide particles, and at the same time, the coating has better oxidation resistance.

[0010] The main phase of the coating is an A3B type compound phase with a face-centered cubic structure of L12, comprising 60% to 95% by volume.

[0011] The nano carbide particles in the coating are mainly chromium carbides with a size of 10–80 nm, and the volume fraction of these carbides accounts for 5%–30% of the coating.

[0012] The coating also contains a small amount of silicon, titanium, and tantalum nanocarbide particles, accounting for 1 to 3% of the coating volume.

[0013] This invention also provides a method for preparing the coating that does not form a needle-like phase at the interface with the nickel-based alloy, namely, preparing the coating by controlling the in-situ reaction of vacuum cathode arc plasma, wherein the preparation steps are as follows:

[0014] ① First, the base material is pretreated by grinding, polishing, and degreasing;

[0015] ② Install the coated target material onto the cathode water-cooled target sleeve, hang the pretreated nickel-based alloy substrate in front of the target, close the vacuum chamber door, and evacuate; the back vacuum of the chamber reaches 6.0 × 10⁻⁶. -3 When Pa or lower, high-purity Ar gas (purity greater than or equal to 99.999%) is introduced into the vacuum chamber to maintain the vacuum level at 1.5 to 5.0 Pa. The bias voltage is set to -700 to -900 V, and the duty cycle is set to 20% to 60%. The sample surface is bombarded with ions for 3 to 10 minutes to remove surface contaminants.

[0016] ③ Ignite the vacuum arc plasma with the coated target material as the cathode;

[0017] ④ Activate the workpiece surface by bombarding it with cations with a charge of 300eV to 1000eV;

[0018] ⑤ The partial pressure of carbon-containing gas is controlled and deposited on the workpiece surface through plasma activation reaction to form a coating. The coating preparation time is 20-100 min.

[0019] The cathode arc plasma current density used to prepare this coating ranges from 1.8 × 10⁻⁶. 4 A / m 2 ~3.5×10 4 A / m 2 .

[0020] The aforementioned carbon-containing gases are methane, ethane, propane, butane, acetylene, propyne, or combinations thereof, with a partial pressure range of 6.0 × 10⁻⁶. -2 Pa ~ 3.0 Pa.

[0021] The coating described in this invention is applicable to various nickel-based superalloys, such as casting, directionally solidified and single-crystal superalloys, and is particularly suitable for single-crystal superalloys, such as CMSX-4, CMSX-8, DD98M, N5, DD3, DD9 and DD15, and can effectively suppress the precipitation of needle-like phases caused by interdiffusion.

[0022] The advantages of this invention are:

[0023] This invention provides a nickel / cobalt-based alloy coating with dispersed nano-carbide particles and interstitial reinforcement by carbon elements. This coating can effectively solve the problem of needle-like harmful phases precipitated by interdiffusion between traditional MCrAlY coatings and nickel-based alloys, especially single-crystal substrates.

[0024] The coating preparation method provided by this invention has advantages such as simple and controllable process, one-step preparation ensuring high coating purity, and green and pollution-free preparation process. It is also suitable for coating preparation of workpieces with various complex geometries. Attached Figure Description

[0025] Figure 1 Nano-carbide and carbon interstitial MCr prepared for vacuum ion plating x C y Scanning electron microscope (SEM) images of the surface (a) and cross-section (b) of the AlY coating;

[0026] Figure 2 MCr nano-carbide interstitial material prepared for vacuum ion plating x C y XRD diffraction pattern of AlY coating; in the figure, the horizontal axis 2θ represents the diffraction angle (deg.), and the vertical axis Intensity represents the relative intensity (au);

[0027] Figure 3 For MCr x C y Scanning electron microscope (SEM) image of the cross-sectional morphology of the AlY coating after oxidation at 1100℃ for 100 h. Detailed Implementation

[0028] The present invention will be further described below with reference to the embodiments and accompanying drawings, but is not limited thereto.

[0029] Unless otherwise specified, the high-temperature alloy substrates used in this embodiment are all pre-treated by grinding, polishing, and degreasing. The Ar gas used is all high-purity Ar gas (purity greater than or equal to 99.999%). The resulting coating consists of carbon-filled nickel-based, cobalt-based, or nickel-cobalt-based alloys and dispersed nano-carbide particles. The nano-carbide particles are mainly composed of chromium carbides, with a size of 10–80 nm. The chromium carbides account for 5%–30% of the coating volume. The nano-carbide particles also contain 1%–3% silicon, titanium, and tantalum carbide ceramic phases by volume. The main phase of the coating is an L12 face-centered cubic A3B type compound phase with a volume fraction of 60%–95%. In the following embodiments, the carbon content of the coating is controlled by adjusting the pressure of the carbon-containing gas. The mass percentage of carbon in all the following coatings is between 0.6 wt.% and 2.8 wt.%.

[0030] Example 1

[0031] This embodiment describes the preparation method of a coating that does not form a needle-like phase at the interface with a nickel-based alloy by vacuum ion plating.

[0032] First, the Ni-30Cr-12Al-0.5Y alloy target was installed on the cathode water-cooled target sleeve. The pretreated second-generation nickel-based single-crystal alloy N5 substrate was hung in front of the target. The vacuum chamber door was closed, and evacuation was performed. The vacuum level at the bottom of the chamber reached 6.0 × 10⁻⁶. -3 When the pressure is 2.0 Pa or lower, turn on the flow meter to introduce Ar gas into the vacuum chamber to maintain the vacuum level at 2.0 Pa. Set the bias voltage to -800 V and the duty cycle to 30%, and bombard the sample surface with ions for about 8 minutes to remove surface contaminants. Then turn off the flow meter to maintain the vacuum level at 10 Pa. -3 The Pa order of magnitude is used. The cathode arc plasma is ignited by an arc-starting needle using a contact method, with an arc current density of 2.5 × 10⁻⁶. 4 A / m 2 The workpiece surface was activated by bombardment with 300 eV cations, and the methane gas flow rate was adjusted to maintain a vacuum of 3.0 Pa for 60 min. The resulting deposited NiCr... x C y AlY coating, scanning electron microscope images of the coating surface and cross-section are shown below. Figure 1As shown, the coating surface is relatively smooth and uniform, with a few scattered small molten droplets. The coating cross-section is dense, with good adhesion to the substrate. There are no obvious pores at the interface or inside the coating, and no obvious precipitates are observed in the coating.

[0033] Phase analysis was performed on the prepared coating. Figure 2 Showing NiCr x C y XRD diffraction pattern of AlY coating. It can be seen that the prepared NiCr... x C y The AlY coating is mainly composed of γ / γ' and Cr. 23 Composed of C6 phase. Figure 3 Showing NiCr x C y The cross-sectional morphology of the AlY coating after oxidation at 1100℃ for 100h is shown in the figure. It can be seen that after high-temperature heat exposure, a large amount of gray-black phase precipitates in the coating, which is identified as a Cr-rich phase by energy dispersive spectroscopy. No obvious interdiffusion zone is generated between the coating and the substrate. A small amount of spherical TCPs phase precipitates below the coating. No needle-like phase forms at the interface between the coating and the nickel-based alloy.

[0034] Example 2

[0035] This embodiment describes the preparation method of a coating that does not form a needle-like phase at the interface with a nickel-based alloy by vacuum ion plating.

[0036] First, install the Ni-20Co-27Cr-10Al-0.5Y-0.5Ti alloy target. Hang the pre-treated cast high-temperature alloy K417 substrate in front of the target, close the vacuum chamber door, and begin evacuation; the back-bottom vacuum level of the chamber reaches 6.0 × 10⁻⁶. -3 When the pressure is 2.0 Pa or lower, turn on the flow meter to introduce Ar gas into the vacuum chamber to maintain the vacuum at 2.0 Pa. Set the bias voltage to -900 V and the duty cycle to 20%. Perform ion bombardment on the sample surface for 10 minutes to remove surface contaminants. After cleaning, turn on the flow meter to introduce a mixture of C2H2 and Ar gas into the vacuum chamber to maintain the vacuum at 2.0 Pa, where the partial pressure of C2H2 is 0.3 Pa. Use the contact method to ignite the cathode arc plasma with an arc-starting needle at a current density of 3.0 × 10⁻⁶ Pa. 4 A / m 2 The surface of the activated substrate was bombarded with 600 eV cations, and after deposition for 30 min, Ni(Cr) containing various carbides was obtained. x C y )AlY(Ti u C v After the sample was exposed to high temperature, no obvious interdiffusion zone was generated between the coating and the substrate, and no needle-like phase was formed at the interface between the coating and the nickel-based alloy.

[0037] Example 3

[0038] This embodiment describes the preparation method of a nickel-cobalt based coating that does not form a needle-like phase at the interface with a nickel-based alloy by vacuum ion plating.

[0039] First, the Ni-20Co-27Cr-10Al-2Si-1Hf alloy target was installed on the cathode water-cooled target sleeve. The pretreated single-crystal DD98M substrate was then hung in front of the target. The vacuum chamber door was closed, and evacuation was performed. The vacuum level at the bottom of the chamber reached 6.0 × 10⁻⁶. -3 When the pressure is 4.0 Pa or lower, turn on the flow meter to introduce Ar gas into the vacuum chamber to maintain the vacuum at 4.0 Pa. Set the bias voltage to -900 V and the duty cycle to 20%, and bombard the sample surface with ions for about 3 minutes. Use the contact method to ignite the cathode arc plasma with an arc-starting needle, and the current density is 3.4 × 10⁻⁶. 4 A / m 2 Then the flow meter was turned off to maintain the vacuum at 10. -3 The pressure valve was opened to introduce CH4 to maintain a vacuum of 0.1 Pa. The substrate surface was then bombarded with 900 eV cations for 30 min. This yielded Ni(Cr) nanoparticles with dispersed nano-carbide particles and carbon doping. x C y )AlY(SiC)(Hf u C v Coating. After high-temperature thermal exposure, no obvious interdiffusion zone was generated between the coating and the substrate, and no needle-like phase was formed at the interface between the coating and the nickel-based alloy.

[0040] Example 4

[0041] This embodiment describes the preparation method of a nickel-cobalt based coating that does not form a needle-like phase at the interface with a nickel-based alloy by vacuum ion plating.

[0042] First, the Ni-30Cr-12Al-1Y-0.7Ta-0.3Re alloy target was installed on the cathode water-cooled target sleeve. The pretreated single-crystal CMSX-4 substrate was hung in front of the target. The vacuum chamber door was closed, and evacuation was performed. The vacuum level at the bottom of the chamber reached 6.0 × 10⁻⁶. -3 When the pressure is 3.0 Pa or lower, turn on the flow meter to introduce Ar gas into the vacuum chamber to maintain the vacuum level at 3.0 Pa. Set the bias voltage to -700 V and the duty cycle to 60%, and bombard the sample surface with ions for about 10 minutes. Use the contact method to ignite the cathode arc plasma with an arc-starting needle, and the current density is 2.0 × 10⁻⁶. 4 A / m 2 Then the flow meter was turned off to maintain the vacuum at 10. -3The pressure valve was opened to introduce a mixed gas of CH4 and C2H2 to maintain a vacuum of 1.0 Pa. The substrate surface was then bombarded with 500 eV cations for 70 min. This yielded Ni(Cr) alloys with a high carbide content. x C y )AlY(Ta u C v Re coating. After high-temperature thermal exposure, no obvious interdiffusion zone was generated between the coating and the substrate, and no needle-like phase was formed at the interface between the coating and the nickel-based alloy.

[0043] Example 5

[0044] This embodiment describes the preparation method of a cobalt-based coating that does not form a needle-like phase at the interface with a nickel-based alloy by vacuum arc ion plating.

[0045] First, the Co-27Cr-14Al-2Y alloy target was installed on the cathode water-cooled target sleeve. The pretreated, oriented columnar DZ417G substrate was then hung in front of the target. The vacuum chamber door was closed, and evacuation was initiated. The vacuum level at the bottom of the chamber reached 6.0 × 10⁻⁶. -3 When the pressure is 5.0 Pa or lower, turn on the flow meter to introduce Ar gas into the vacuum chamber to maintain the vacuum level at 5.0 Pa. Set the bias voltage to 800 V and the duty cycle to 40%, and bombard the sample surface with ions for about 7 minutes. Use the contact method to ignite the cathode arc plasma with an arc-starting needle, and the current density is 2.3 × 10⁻⁶. 4 A / m 2 Then the flow meter was turned off to maintain the vacuum at 10. -3 The pressure valve was opened to introduce a mixed gas of C3H4 and Ar to maintain a vacuum of 1.5 Pa, with a C3H4 partial pressure of 0.5 Pa. The substrate surface was then bombarded with 450 eV cations for 20 min to obtain carbide-modified CoCr. x C y AlY coating. After high-temperature thermal exposure, no obvious interdiffusion zone was generated between the coating and the substrate, and no needle-like phase was formed at the interface between the coating and the nickel-based alloy.

[0046] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A coating that does not form a needle-like phase at the interface with a nickel-based alloy, characterized in that: The coating consists of carbon-filled nickel-based, cobalt-based, or nickel-cobalt-based alloys and dispersed nano-carbide particles; the chemical composition of the coating is: nickel 0~75wt.%, cobalt 0~75wt.%, chromium 8wt.%~32wt.%, aluminum 6wt.%~16wt.%, carbon 0.4wt.%~3.5wt.%, and other metal components not exceeding 5wt.% in total; the other metal components are one or more combinations of rare earth elements, hafnium, zirconium, titanium, silicon, tantalum, rhenium, and ruthenium; the nano-carbide particles are mainly composed of chromium carbides with a size of 10~80nm, and the chromium carbides account for 5%~30% of the coating volume fraction; the main phase of the coating is an L12 face-centered cubic A3B type compound phase with a volume fraction of 60%~95%.

2. The coating according to claim 1 that does not form a needle-like phase at the interface with the nickel-based alloy, characterized in that: The nano-carbide particles also contain a silicon, titanium, or tantalum carbide ceramic phase accounting for 1-3% of the coating volume fraction.

3. A method for preparing a coating that does not form a needle-like phase at the interface with a nickel-based alloy as described in claim 1, characterized in that, The coating was prepared by controlling the in-situ reaction of vacuum cathode arc plasma. The preparation steps are as follows: ① First, the base material is pretreated by grinding, polishing, and degreasing; ② Install the coated target material onto the cathode water-cooled target sleeve, hang the pretreated nickel-based alloy substrate in front of the target, close the vacuum chamber door, and evacuate; the back vacuum of the chamber reaches 6.0 × 10⁻⁶. -3 When the pressure is Pa or lower, Ar gas is introduced into the vacuum chamber to maintain the vacuum level at 1.5~5.0 Pa, the bias voltage is set to -700~-900V, the duty cycle is set to 20%~60%, and the sample surface is bombarded with ions for 3~10 minutes to remove surface contaminants. ③ Ignite the vacuum arc plasma with the coated target material as the cathode; ④ Activate the workpiece surface by bombarding it with cations with a charge of 300eV~1000eV; ⑤ The partial pressure of carbon-containing gas is controlled and deposited on the workpiece surface through plasma activation reaction to form a coating. The coating preparation time is 20~100min.

4. The method for preparing a coating that does not form a needle-like phase at the interface with the nickel-based alloy according to claim 3, characterized in that: The cathode arc plasma current density ranges from 1.8 × 10⁻⁶. 4 A / m 2 ~3.5×10 4 A / m 2 .

5. The method for preparing a coating that does not form a needle-like phase at the interface with the nickel-based alloy according to claim 4, characterized in that: The carbon-containing gas is methane, ethane, propane, butane, acetylene, propyne, or a combination thereof, with a partial pressure range of 6.0 × 10⁻⁶. -2 Pa ~ 3.0 Pa.

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