A modified mcraly coating and method of making same, single crystal high temperature alloy

Abstract

This invention provides a modified MCrAlY coating and its preparation method, as well as a single-crystal high-temperature alloy. The chemical composition of the modified MCrAlY coating, by mass percentage, is as follows: Cr 20–30 wt%, Co 10–20 wt%, Al 5–15 wt%, Y 0.5–1.5 wt%, Si 0.05–0.15 wt%, with the remainder being Ni. The modified MCrAlY coating of this invention exhibits excellent high-temperature oxidation resistance, with high resistance to peeling of its surface oxide layer and high strength. After composition optimization, the volume gain of the modified MCrAlY coating decreased by 50% after 200 hours of oxidation at 1140℃. Simultaneously, this modified MCrAlY coating exhibits excellent hot corrosion resistance, with a weight gain of only 0.3 mg / cm³ after 200 hours of hot corrosion at 900℃. 2 The modified MCrAlY coating of this invention is suitable for high-temperature protection of long-life, high-reliability hot-end high-temperature components in the fields of aviation, aerospace, and energy.

Description

Technical Field

[0001] This invention relates to the field of high-temperature protective coating preparation technology, and in particular to a modified MCrAlY coating and its preparation method, and a single-crystal high-temperature alloy. Background Technology

[0002] High-temperature alloys are widely used as hot-end components in the aerospace industry due to their excellent mechanical properties and resistance to high-temperature creep. To continuously improve the efficiency of gas turbine engines, advanced gas turbines can achieve inlet temperatures of up to 1600℃, and blade operating temperatures of 1000℃ to 1200℃. Because blades operate at the highest temperatures and experience complex stresses, new engine rotor blades utilize nickel-based single-crystal high-temperature alloys with higher heat resistance as structural materials. To protect these critical hot-end components and extend their reliable service life, a high-temperature protective coating is typically applied to the blade surface to protect the base alloy from accelerated degradation due to high-temperature oxidation.

[0003] Compared to traditional diffusion coatings, MCrAlY coatings exhibit superior environmental resistance and adaptability. The coating composition and thickness can be adjusted according to the service environment and substrate alloy, thereby reducing interdiffusion between the coating and the substrate and minimizing mechanical damage to the substrate. Therefore, the selection and control of the MCrAlY coating composition significantly impacts the performance of both the coating and the substrate. Currently, numerous active elements are added to the coating for modification. Si, in particular, can improve the oxide film's resistance to exfoliation and increase the time before exfoliation, while also providing good corrosion resistance. However, excessive Si content increases the ratio of the volume of a single metal ion to the volume of each metal atom in the oxide film, generating excessive compressive stress that can easily cause oxide film rupture and reduce the coating's oxidation resistance. Therefore, considering that Si may exacerbate oxide film stress while improving its resistance to exfoliation, and taking into account the advantages and disadvantages of other components, how to rationally formulate the coating composition to provide a high-performance MCrAlY coating is a pressing issue that needs to be addressed.

[0004] In summary, existing MCrAlY coatings have at least the following technical problems:

[0005] Existing MCrAlY coatings, while improving the anti-peeling ability of the oxide film on the coating, are prone to problems such as increased stress on the oxide film and oxide film cracking. Summary of the Invention

[0006] In view of this, the present invention provides a modified MCrAlY coating and its preparation method, as well as a single-crystal high-temperature alloy, which can solve the problem that existing MCrAlY coatings, while improving the anti-peeling ability of the oxide film on the coating, are prone to causing increased stress and rupture of the oxide film.

[0007] To address the aforementioned problems, this invention provides a modified MCrAlY coating. The chemical composition of the modified MCrAlY coating, by mass percentage, is as follows: Cr 20–30 wt%, Co 10–20 wt%, Al 5–15 wt%, Y 0.5–1.5 wt%, Si 0.05–0.15 wt%, with the remainder being Ni.

[0008] The aforementioned modified MCrAlY coating has the following chemical composition by mass percentage: Cr 23-28wt%, Co 13-18wt%, Al 8-12wt%, Y 0.8-1.3wt%, Si 0.06-0.12wt%, with the remainder being Ni.

[0009] In the aforementioned modified MCrAlY coating, the mass percentage of Si is a, and the sum of the mass percentages of Al and Cr is b; where a / b = 1.5 × 10⁻⁶. -3 ~3×10 -3 .

[0010] The aforementioned modified MCrAlY coating, in the case where the modified MCrAlY coating is deposited on the surface of a carrier;

[0011] A dense oxide film with a pinned morphology is formed on the surface of the modified MCrAlY coating to improve the anti-peeling ability of the oxide film on the surface of the modified MCrAlY coating.

[0012] And / or, the PB ratio of the oxide film on the surface of the modified MCrAlY coating is 1.5-1.8;

[0013] And / or, the modified MCrAlY coating contains 55-60% by volume of β phase and 40-45% by volume of γ' phase to improve its high-temperature strength.

[0014] This invention also provides a method for preparing a modified MCrAlY coating, which includes the following steps:

[0015] The above-mentioned method for preparing a modified MCrAlY coating includes the following steps:

[0016] Preparation of alloy powder: Prepare master alloy ingots and then prepare alloy powder from the master alloy ingots;

[0017] Preparation of a coated carrier: The carrier is pretreated, and alloy powder is deposited on the pretreated carrier to obtain a coated carrier;

[0018] In the aforementioned method for preparing a modified MCrAlY coating, the alloy powder is prepared by vacuum atomization treatment to convert the master alloy ingot into alloy powder.

[0019] In the aforementioned method for preparing a modified MCrAlY coating, the pretreatment in preparing the carrier containing the coating includes electrochemical degreasing and activation treatment of the carrier in sequence.

[0020] Preferably, the carrier is subjected to surface treatment before pretreatment, wherein the surface treatment includes grinding, wet sandblasting and ultrasonic treatment performed in sequence.

[0021] In the aforementioned method for preparing a modified MCrAlY coating, in the preparation of the substrate containing the coating: the pretreated substrate is pre-sputtered and cleaned;

[0022] Preferably, the parameters for pre-sputter cleaning are controlled as follows:

[0023] The carrier and furnace cavity are subjected to air steam treatment for 10-15 minutes to obtain the deposition environment atmosphere. After the alloy powder is loaded into the furnace, the furnace cavity is evacuated to 7×10-3 to 8×10-3 Pa, the temperature is raised to 100-120℃, inert gas is introduced into the vacuum chamber and the gas pressure is maintained at 0.23-0.25 Pa. Pre-sputtering cleaning is performed under the conditions of bias voltage of -600V to -800V, duty cycle of 25-30%, and arc current of 55-65A. The sputtering voltage is controlled at -15 to -20V and the sputtering time is 3-5 minutes.

[0024] In the aforementioned method for preparing a modified MCrAlY coating, in the preparation of the carrier containing the coating: the alloy powder is deposited on the pretreated carrier using an arc ion plating deposition technique to obtain the carrier containing the coating;

[0025] Preferably, the parameters for arc ion plating deposition technology are controlled as follows:

[0026] The target-substrate distance is 220mm to 280mm, the arc voltage is 20V to 25V, the arc current is 70A to 90A, the pulse bias voltage is -150 to -300V, the duty cycle is 20% to 40%, the deposition temperature is 150℃ to 300℃, the deposition time is 2h to 5h, and the coating thickness is 40μm to 60μm.

[0027] In the aforementioned method for preparing a modified MCrAlY coating, the heat treatment employed is vacuum heat treatment.

[0028] The parameters for vacuum heat treatment are controlled as follows:

[0029] Vacuum gradient heat treatment is adopted, with treatment at 650℃~800℃ for 2~4h and at 900℃~1000℃ for 2~4h; the heating and cooling rates are controlled at 1-3℃ / min.

[0030] The present invention also provides a material for preparing a modified MCrAlY coating. The chemical composition of the material for preparing the modified MCrAlY coating, by mass percentage, is as follows: Cr 20-30wt%, Co 10-20wt%, Al 5-15wt%, Y 0.5-1.5wt%, Si 0.05-0.15wt%, with the remainder being Ni.

[0031] Preferably, the mass percentage of Si is a, and the sum of the mass percentages of Al and Cr is b; where a / b = 1.5 × 10⁻⁶. -3 ~3×10 -3 .

[0032] The present invention also provides a single-crystal high-temperature alloy, which includes a single-crystal high-temperature alloy substrate and a modified MCrAlY coating deposited on the single-crystal high-temperature alloy substrate; wherein, the modified MCrAlY coating is the modified MCrAlY coating described above.

[0033] Preferably, the single-crystal high-temperature alloy matrix is ​​a single-crystal high-temperature alloy blade.

[0034] Compared with the prior art, the modified MCrAlY coating and its preparation method, as well as the single-crystal high-temperature alloy provided by the present invention, have at least the following beneficial effects.

[0035] On one hand, this invention provides a modified MCrAlY coating with the following chemical composition: Cr 20-30 wt%, Co 10-20 wt%, Al 5-15 wt%, Y 0.5-1.5 wt%, Si 0.05-0.15 wt%, and the remainder being Ni. It should be noted that the MCrAlY coating of this invention incorporates trace amounts of Si. The Si reacts with oxygen along the grain boundaries of the oxide film to form SiO2, resulting in SiO2 present on and below the grain boundaries of the MCrAlY coating surface. This causes the SiO2 to be embedded into the surface of the MCrAlY coating in a pinning manner, forming a dense oxide film with a pinned morphology. This firmly anchors the oxide film to the MCrAlY coating surface, thus giving the modified MCrAlY coating surface oxide film excellent anti-peeling ability. Simultaneously, Si, in conjunction with Al and Cr, lowers the critical content value for Al and Cr oxidation on the surface of the modified MCrAlY coating. The presence of trace amounts of Si promotes the formation of Al₂O₃ and Cr₂O₃ oxides on the coating surface, preventing internal oxidation of the modified MCrAlY coating and resulting in a stable oxide film on the surface, thus giving the coating high-temperature oxidation resistance. The trace amount of Si maintains a PB ratio of 1.5-1.8 on the oxide film surface of the modified MCrAlY coating, keeping the stress within a reasonable range and preventing the oxide film from cracking, thereby improving the high-temperature oxidation resistance of the modified MCrAlY coating.

[0036] Meanwhile, the addition of Y element in this invention can alter the microstructure and growth mechanism of the oxide film, improving its plasticity and resistance to peeling. Furthermore, Y element can utilize vacancy roughening to eliminate porosity at the interface between the coating and the oxide film, enhancing the adhesion between the modified MCrAlY coating and the oxide film. This further improves the oxide film's resistance to peeling.

[0037] On the other hand, the modified MCrAlY coating of this invention has the advantage of controlling the content of Si, Al, and Cr: Si / (Al+Cr) = 1.5 × 10⁻⁶. -3 ~3×10 -3 During hot corrosion, the oxide film on the surface of the modified MCrAlY coating also forms a pinned shape, ensuring the oxide film has excellent resistance to hot corrosion. Experimental tests show that the modified MCrAlY coating gains only 0.3 mg / cm³ after 200 hours of hot corrosion at 900℃. 2 It is superior to traditional MCrAlY coatings.

[0038] Furthermore, Cr ensures the coating possesses excellent high-temperature oxidation resistance, improves its resistance to Type II hot corrosion, and reduces the minimum Al content required to form a continuous Al2O3 layer. Simultaneously, Cr can react with O to form a Cr2O3 film, primarily serving to resist hot corrosion. However, high Cr content can impair the adhesion between the oxide film and the coating. Therefore, this invention employs a suitable amount of Cr to improve the coating's high-temperature oxidation resistance and hot corrosion resistance.

[0039] On the other hand, the addition of trace amounts of Si in this invention can prevent excessive Si from forming a brittle phase inside the coating, thereby improving the strength of the modified MCrAlY coating itself. At the same time, the limited use of Si also reduces the design and usage costs of the coating.

[0040] On the other hand, Co is mainly used to alleviate interfacial stress between the modified MCrAlY coating and the high-temperature alloy substrate, thereby improving the interfacial stability between the coating and the substrate. However, a high Co content can lead to the formation of a Co-rich phase, which is inconsistent with the coating potential and easily becomes a micro-cathode region, accelerating coating corrosion. Therefore, this invention designs a reasonable Co content of 10–20 wt%, which can effectively improve the interfacial stability between the modified MCrAlY coating and the high-temperature alloy substrate.

[0041] Furthermore, the present invention performs electrochemical degreasing and activation treatment on the carrier, and removes the oxide film on the surface of the carrier through pretreatment, thereby further improving the adhesion between the MCrAlY coating and the high-temperature alloy substrate. Attached Figure Description

[0042] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0043] Figure 1 This is a comparative schematic diagram showing the cross-sectional microstructure of the modified MCrAlY coating of Example 1 and the MCrAlY coating of Comparative Example 1.

[0044] Figure 2 This is a schematic diagram comparing the oxidation weight gain curves of the modified MCrAlY coating in Example 2 of the present invention with those of the MCrAlY coating in Comparative Example 1.

[0045] Figure 3 This is a schematic diagram comparing the cross-sectional microstructure of the modified MCrAlY coating of Example 3 and the MCrAlY coating of Comparative Example 1 after oxidation at 1000℃ for 200h.

[0046] Figure 4 This is a schematic diagram comparing the weight gain curves of the modified MCrAlY coating of Example 4 of the present invention and the MCrAlY coating of Comparative Example 1 under the condition of hot corrosion at 900℃ for 200h.

[0047] Figure 5 This is a comparative schematic diagram showing the weight gain of the modified MCrAlY coating of Example 5, the modified MCrAlY coating of Example 4, and the MCrAlY coating of Comparative Example 1 under the condition of hot corrosion at 900°C for 200 hours. Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] Further optimization is needed to achieve an MCrAlY coating with high high-temperature oxidation resistance and strong resistance to peeling of the surface oxide film.

[0050] The main solution of the present invention is as follows:

[0051] This invention provides a modified MCrAlY coating. The chemical composition of the modified MCrAlY coating, by mass percentage, is as follows: Cr 20-30wt%, Co 10-20wt%, Al 5-15wt%, Y 0.5-1.5wt%, Si 0.05-0.15wt%, with the remainder being Ni.

[0052] Based on the above component ratios, the main inventive concept of this invention is as follows: Regarding the composition of the modified MCrAlY coating, this invention employs trace amounts of Si. Si reacts with oxygen along the oxide film grain boundaries to form stable SiO2, which firmly anchors the oxide film to the surface of the modified MCrAlY coating. This significantly improves the anti-peeling ability of the oxide film on the MCrAlY coating surface, reduces the tendency of the oxide film to crack, and prolongs the time before peeling. Simultaneously, the Si element, in conjunction with Al and Cr elements, lowers the critical content value for Al and Cr oxidation on the surface of the modified MCrAlY coating. The presence of trace amounts of Si promotes the formation of Al2O3 and Cr2O3 oxides on the coating surface, preventing internal oxidation of the modified MCrAlY coating and resulting in a stable oxide film on the surface of the modified MCrAlY coating. Based on the above, the PB ratio of the oxide film on the surface of the modified MCrAlY coating of this invention is 1.5-1.8, making the oxide film less prone to cracking. In summary, the Si content of the modified MCrAlY coating of this invention is selected to be 0.05-0.15 wt%. It can improve the oxide's resistance to peeling while giving the coating better strength and controlling the stress of the oxide film within a reasonable range, thereby enhancing the high-temperature oxidation resistance of the oxide film.

[0053] On the other hand, the addition of Y element in this invention can alter the microstructure and growth mechanism of the oxide film, improving its plasticity and resistance to peeling. Simultaneously, Y element can utilize vacancy roughening to eliminate porosity at the interface between the coating and the oxide film, thereby enhancing the adhesion between them. Therefore, a certain amount of Y element needs to be added to the coating; the Y content of the coating in this invention is 0.5–1.5 wt%.

[0054] Meanwhile, the use of Cr in this invention ensures the coating has excellent high-temperature oxidation resistance, improves its resistance to Type II hot corrosion, and reduces the minimum Al content required to form a continuous Al2O3 layer. Cr can also react with O to form a Cr2O3 film, primarily serving to resist hot corrosion. However, a high Cr content in the coating can impair the adhesion between the oxide film and the coating surface. Therefore, this invention requires a moderately controlled increase in Cr content, with a Cr content of 20–30 wt%.

[0055] The Co element used in this invention is primarily to alleviate interfacial stress between the coating and the substrate, thereby improving the interfacial stability. However, a high Co content can lead to the formation of a Co-rich phase, which is inconsistent with the coating potential and easily becomes a microcathodic region, accelerating coating corrosion. Therefore, the Co content of the modified MCrAlY coating in this invention is controlled at 10–20 wt%.

[0056] This invention utilizes Al, the most important precipitation-strengthening γ' phase-forming element in high-temperature alloys. This allows the coating to contain 55-60% β phase and 40-45% γ' phase by volume. Because the γ' phase has high high-temperature strength, this invention further increases the volume fraction of the γ' phase within the coating by controlling the Al content, thereby improving the coating's high-temperature strength. Simultaneously, Al reacts with O in the environment to form a dense alumina layer that prevents further oxidation of the internal coating and substrate. Therefore, the Al content of the coating in this invention is 5-15 wt%.

[0057] Furthermore, the chemical composition of the modified MCrAlY coating, by mass percentage, is as follows: Cr 23-28wt%, Co 13-18wt%, Al 8-12wt%, Y 0.8-1.3wt%, Si 0.06-0.12wt%, with the remainder being Ni.

[0058] Furthermore, in the modified MCrAlY coating, the mass percentage of Si is a, and the sum of the mass percentages of Al and Cr is b; where a / b = 1.5 × 10⁻⁶. -3 ~3×10 -3 .

[0059] The modified MCrAlY coating of this invention achieves this effect by controlling the content of Si, Al, and Cr: Si / (Al+Cr) = 1.5 × 10⁻⁶. -3 ~3×10 -3 This ensures the oxide film possesses excellent resistance to hot corrosion. Experimental tests show that the modified MCrAlY coating only gained 0.3 mg / cm³ after 200 hours of hot corrosion at 900℃. 2 It is superior to traditional MCrAlY coatings.

[0060] Furthermore, the aforementioned modified MCrAlY coating is applied to the surface of a single-crystal superalloy.

[0061] A dense oxide film with a pinned morphology is formed on the surface of the modified MCrAlY coating to improve the anti-peeling ability of the oxide film on the surface of the modified MCrAlY coating.

[0062] And / or, the PB ratio of the oxide film on the surface of the modified MCrAlY coating is 1.5-1.8;

[0063] And / or, the modified MCrAlY coating contains 55-60% by volume of β phase and 40-45% by volume of γ' phase to improve its high-temperature strength.

[0064] In this invention, a modified MCrAlY coating incorporates trace amounts of Si. The Si reacts with oxygen along the oxide film grain boundaries to form stable SiO2, creating a pinned oxide film that firmly anchors the coating to the MCrAlY surface. This induces an external oxidation process within the coating, resulting in a denser, pinned oxide film with excellent high-temperature oxidation resistance. Al, used in this invention, is the primary precipitation-strengthening element for the γ' phase in high-temperature alloys, ensuring the coating contains 30-40% γ' phase and 55-60% β phase by volume, thus guaranteeing high-temperature strength. Simultaneously, the PB ratio of the modified MCrAlY oxide film increases to 1.5-1.8, enhancing the compressive stress of the modified MCrAlY coating, with a weight gain of less than 1.0 mg / cm³ after 200 hours of oxidation at 1000℃. 2 .

[0065] This invention also provides a method for preparing a modified MCrAlY coating, which includes the following steps:

[0066] Preparation of alloy powder: Prepare master alloy ingots and then prepare alloy powder from the master alloy ingots;

[0067] Preparation of a coated carrier: The carrier is pretreated, and alloy powder is deposited on the pretreated carrier to obtain a coated carrier;

[0068] Preparation of modified MCrAlY coating: The carrier containing the coating is heat-treated to form a modified MCrAlY coating on the surface of the carrier.

[0069] Furthermore, the master alloy ingot is prepared into alloy powder by vacuum atomization.

[0070] This invention uses vacuum atomization to prepare alloy powder from master alloy ingots, thereby making the composition of the prepared alloy powder more uniform.

[0071] Furthermore, the present invention sequentially performs electrochemical degreasing and activation treatment on the high-temperature alloy matrix.

[0072] As a preferred option, the high-temperature alloy substrate is first subjected to surface treatment before pretreatment. The surface treatment includes: grinding, wet sandblasting, and ultrasonic treatment performed in sequence.

[0073] As a reasonable option, the high-temperature alloy substrate was polished in sequence on a pre-grinding machine using SiC sandpaper of 150#, 240#, 400#, 600# and 800# to remove the oxide film on the substrate surface. After the fresh surface of the high-temperature alloy substrate was polished out, a sample was formed. The sample was then subjected to wet sandblasting, followed by ultrasonic treatment with acetone and alcohol in sequence to remove residual oil and other contaminants on the sample surface and improve the cleanliness of the sample surface.

[0074] This invention employs electrochemical degreasing and activation treatment. The purpose of electrochemical degreasing is to further remove dirt and grease, ensuring the cleanliness of the high-temperature alloy substrate surface. The activation treatment increases the roughening effect on the surface of the high-temperature alloy substrate, thereby further increasing the adhesion between the MCrAlY coating and the high-temperature alloy substrate.

[0075] Furthermore, the pretreated carrier is subjected to pre-sputter cleaning, and the parameters for pre-sputter cleaning are controlled as follows:

[0076] The carrier and furnace cavity were subjected to air steam treatment for 10–15 minutes to obtain a stable deposition environment; after the alloy powder was loaded into the furnace, the furnace cavity was evacuated to 7 × 10⁻⁶. -3 ~8×10 -3 Pa, raise the temperature to 100-120℃, fill the vacuum chamber with argon gas and maintain the gas pressure at 0.23-0.25Pa; then perform pre-sputter cleaning under the conditions of bias voltage -600V-800V, duty cycle of 25-30%, and arc current of 55-65A, controlling the sputtering voltage at -15-20V and sputtering for 3-5 minutes.

[0077] Furthermore, in step 3), the specific parameters of the arc ion plating deposition technology are controlled as follows:

[0078] The target-substrate distance is 220mm to 280mm, the arc voltage is 20V to 25V, the arc current is 70A to 90A, the pulse bias voltage is -150 to -300V, the duty cycle is 20% to 40%, the deposition temperature is 150℃ to 300℃, the deposition time is 2h to 5h, and the coating thickness is 40μm to 60μm.

[0079] The present invention can improve the adhesion between the high-temperature alloy substrate and the coating by using pre-sputter cleaning; and the present invention uses arc ion plating deposition technology to make the composition of the coating more uniform.

[0080] Furthermore, vacuum heat treatment is employed.

[0081] The parameters for vacuum heat treatment are controlled as follows:

[0082] Vacuum gradient heat treatment is adopted, with treatment at 650℃~800℃ for 2~4h and at 900℃~1000℃ for 2~4h; the heating and cooling rates are controlled at 1-3℃ / min.

[0083] This invention involves performing gradient vacuum heat treatment on the deposited modified MCrAlY coating to ensure that Si is uniformly present in the β phase of the coating. Combined with the use of trace amounts of Si element in this application, it is possible to ensure that Si element is uniformly dissolved in the β phase of the coating, which will significantly improve the morphology of the oxide film on the surface of the coating after oxidation, thereby enhancing the high-temperature oxidation resistance of the coating.

[0084] The present invention also provides a material for preparing a modified MCrAlY coating. The chemical composition of the material for preparing the modified MCrAlY coating, by mass percentage, is as follows: Cr 20-30wt%, Co 10-20wt%, Al 5-15wt%, Y 0.5-1.5wt%, Si 0.05-0.15wt%, with the remainder being Ni.

[0085] Preferably, the mass percentage of Si is a, and the sum of the mass percentages of Al and Cr is b; where a / b = 1.5 × 10⁻⁶. -3 ~3×10 -3 .

[0086] The present invention also provides a single-crystal high-temperature alloy, which includes a single-crystal high-temperature alloy substrate and a modified MCrAlY coating deposited on the single-crystal high-temperature alloy substrate; wherein, the modified MCrAlY coating is the modified MCrAlY coating described above.

[0087] The single-crystal superalloy substrate can be a single-crystal superalloy blade. By using the single-crystal superalloy of the present invention as the substrate, the blade forms the modified MCrAlY coating of the present invention on the superalloy substrate, which makes the blade have better high-temperature oxidation resistance and corrosion resistance. Its surface oxide film has high resistance to peeling and high strength, and excellent performance.

[0088] The following detailed description of the modified MCrAlY coating, its preparation method, and the high-temperature alloy substrate of the present invention is provided through specific embodiments and comparative examples.

[0089] Example 1

[0090] This embodiment prepares a modified MCrAlY coating, mainly including the following steps:

[0091] Step 1): The composition is Cr: 23%, Co: 17%, Al: 7%, Y: 0.9%, Si: 0.08%, with the remainder being Ni, where Si / (Al+Cr) = 2.7 × 10⁻⁶. -3 The master alloy ingot was prepared and then alloy powder was prepared by vacuum atomization.

[0092] Step 2) Grind the single crystal high-temperature alloy substrate in sequence on the pre-grinding machine using SiC sandpaper of 150#, 240#, 400#, 600# and 800#. After grinding out the fresh surface of the single crystal high-temperature alloy substrate, a sample is formed. The sample is then subjected to wet sandblasting treatment, followed by ultrasonic treatment with acetone and alcohol in sequence.

[0093] Step 3) First, the single-crystal superalloy substrate and furnace cavity are subjected to 12 minutes of air steam treatment to obtain a stable deposition environment. After the sample is loaded into the furnace, the furnace cavity is evacuated to 7 × 10⁻⁶. -3 Pa, temperature rise of 110℃, argon gas is introduced into the vacuum chamber to maintain a pressure of 0.24Pa; then pre-sputter cleaning is performed under the conditions of bias voltage of -700V, duty cycle of 25%, arc current of 60A, sputtering voltage of -18V, sputtering for 4min.

[0094] MCrAlY coating was deposited on a single-crystal high-temperature alloy substrate with a target-substrate distance of 260 mm, an arc voltage of 25 V, an arc current of 77 A, a pulse bias of -220 V, a duty cycle of 30%, a deposition temperature of 230 °C, a deposition time of 3 h, and a coating thickness of 57 μm.

[0095] Step 4) After the arc ion plating deposition is completed, the single crystal high-temperature alloy substrate containing the coating is subjected to vacuum annealing under vacuum conditions: vacuum gradient heat treatment at 700℃ for 4 hours and at 950℃ for 3 hours, with the heating and cooling rates controlled at 1℃ / min, to form a modified MCrAlY coating on the surface of the single crystal high-temperature alloy substrate.

[0096] Example 2

[0097] Step 1): The composition is as follows: Cr: 25%, Co: 16%, Al: 13%, Y: 1.3%, Si: 0.11%, with the remainder being Ni, where Si / (Al+Cr) = 2.9 × 10⁻⁶. -3 The master alloy ingot was prepared and then alloy powder was prepared by vacuum atomization.

[0098] Step 2) Grind the single crystal high-temperature alloy substrate in sequence on the pre-grinding machine using SiC sandpaper of 150#, 240#, 400#, 600# and 800#. After grinding out the fresh surface of the single crystal high-temperature alloy substrate, a sample is formed. The sample is then subjected to wet sandblasting treatment, followed by ultrasonic treatment with acetone and alcohol in sequence.

[0099] Step 3) First, the single-crystal superalloy substrate and furnace cavity are subjected to 12 minutes of air steam treatment to obtain a stable deposition environment. After the sample is loaded into the furnace, the furnace cavity is evacuated to 7 × 10⁻⁶. -3Pa, temperature rise of 110℃, argon gas is introduced into the vacuum chamber to maintain a pressure of 0.24Pa; then pre-sputter cleaning is performed under the conditions of bias voltage of -700V, duty cycle of 25%, arc current of 60A, sputtering voltage of -18V, sputtering for 4min.

[0100] MCrAlY coating was deposited on a single-crystal high-temperature alloy substrate with the following parameters: target-substrate distance of 240 mm, arc voltage of 22 V, arc current of 80 A, pulse bias of -260 V, duty cycle of 25%, deposition temperature of 250 °C, deposition time of 2.5 h, and coating thickness of 50 μm.

[0101] Step 4) After the arc ion plating deposition is completed, the single crystal high-temperature alloy substrate containing the coating is subjected to vacuum annealing under vacuum conditions: vacuum gradient heat treatment at 680℃ for 4 hours and at 970℃ for 2 hours, with the heating and cooling rates controlled at 1℃ / min, to form a modified MCrAlY coating on the surface of the single crystal high-temperature alloy substrate.

[0102] Example 3

[0103] Step 1): The composition is as follows: Cr: 27%, Co: 12%, Al: 12%, Y: 1.4%, Si: 0.08%, with the remainder being Ni, where Si / (Al+Cr) = 2.1 × 10⁻⁶. -3 The master alloy ingot was prepared and then alloy powder was prepared by vacuum atomization.

[0104] Step 2) Grind the single crystal high-temperature alloy substrate in sequence on the pre-grinding machine using SiC sandpaper of 150#, 240#, 400#, 600# and 800#. After grinding out the fresh surface of the single crystal high-temperature alloy substrate, a sample is formed. The sample is then subjected to wet sandblasting treatment, followed by ultrasonic treatment with acetone and alcohol in sequence.

[0105] Step 3) First, the single-crystal superalloy substrate and furnace cavity are subjected to 12 minutes of air steam treatment to obtain a stable deposition environment. After the sample is loaded into the furnace, the furnace cavity is evacuated to 7 × 10⁻⁶. -3 Pa, temperature rise of 110℃, argon gas is introduced into the vacuum chamber to maintain a pressure of 0.24Pa; then pre-sputter cleaning is performed under the conditions of bias voltage of -700V, duty cycle of 25%, arc current of 60A, sputtering voltage of -18V, sputtering for 4min.

[0106] MCrAlY coating was deposited on a single-crystal high-temperature alloy substrate with a target-substrate distance of 240 mm, an arc voltage of 25 V, an arc current of 83 A, a pulse bias of -260 V, a duty cycle of 24%, a deposition temperature of 180 °C, a deposition time of 4 h, and a coating thickness of 46 μm.

[0107] Step 4) After the arc ion plating deposition is completed, the single crystal high-temperature alloy substrate containing the coating is subjected to vacuum annealing under vacuum conditions: vacuum gradient heat treatment at 750℃ for 3h and 930℃ for 3h, with the heating and cooling rates controlled at 1℃ / min, to form a modified MCrAlY coating on the surface of the single crystal high-temperature alloy substrate.

[0108] Example 4

[0109] Step 1): The composition is as follows: Cr: 25%, Co: 18%, Al: 15%, Y: 0.8%, Si: 0.12%, with the remainder being Ni, where Si / (Al+Cr) = 3 × 10⁻⁶. -3 A master alloy ingot was prepared, and then powders of the same composition were prepared by vacuum atomization.

[0110] Step 2) Grind the single crystal high-temperature alloy substrate in sequence on the pre-grinding machine using SiC sandpaper of 150#, 240#, 400#, 600# and 800#. After grinding out the fresh surface of the single crystal high-temperature alloy substrate, a sample is formed. The sample is then subjected to wet sandblasting treatment, followed by ultrasonic treatment with acetone and alcohol in sequence.

[0111] Step 3) First, the single-crystal superalloy substrate and furnace cavity are subjected to 12 minutes of air steam treatment to obtain a stable deposition environment. After the sample is loaded into the furnace, the furnace cavity is evacuated to 7 × 10⁻⁶. -3 Pa, temperature rise of 110℃, argon gas is introduced into the vacuum chamber to maintain a pressure of 0.24Pa; then pre-sputter cleaning is performed under the conditions of bias voltage of -700V, duty cycle of 25%, arc current of 60A, sputtering voltage of -18V, sputtering for 4min.

[0112] MCrAlY coating was deposited on a single-crystal high-temperature alloy substrate with a target-substrate distance of 270 mm, an arc voltage of 22 V, an arc current of 85 A, a pulse bias of -190 V, a duty cycle of 22%, a deposition temperature of 280 °C, a deposition time of 4 h, and a coating thickness of 60 μm.

[0113] Step 4) After the arc ion plating deposition is completed, the single crystal high-temperature alloy substrate containing the coating is subjected to vacuum annealing under vacuum conditions: vacuum gradient heat treatment at 800℃ for 2 hours and 950℃ for 2 hours, with the heating and cooling rates controlled at 1℃ / min, to form a modified MCrAlY coating on the surface of the single crystal high-temperature alloy substrate.

[0114] Example 5

[0115] Step 1): The composition is as follows: Cr: 25%, Co: 18%, Al: 15%, Y: 0.8%, Si: 0.15%, with the remainder being Ni, where Si / (Al+Cr) = 3.75 × 10⁻⁶.-3 ; Prepare a master alloy ingot, and then prepare powder of the same composition by vacuum atomization. Step 2) Grind the single crystal high temperature alloy substrate in sequence on a pre-grinding machine using SiC sandpaper of 150#, 240#, 400#, 600# and 800#. After grinding out the fresh surface of the single crystal high temperature alloy substrate, a sample is formed. The sample is then subjected to wet sandblasting treatment, and then ultrasonic treatment is performed on the sample in sequence using acetone and alcohol.

[0116] Step 3) First, the single-crystal superalloy substrate and furnace cavity are subjected to 12 minutes of air steam treatment to obtain a stable deposition environment. After the sample is loaded into the furnace, the furnace cavity is evacuated to 7 × 10⁻⁶. -3 Pa, temperature rise of 110℃, argon gas is introduced into the vacuum chamber to maintain a pressure of 0.24Pa; then pre-sputter cleaning is performed under the conditions of bias voltage of -700V, duty cycle of 25%, arc current of 60A, sputtering voltage of -18V, sputtering for 4min.

[0117] MCrAlY coating was deposited on a single-crystal high-temperature alloy substrate with a target-substrate distance of 270 mm, an arc voltage of 22 V, an arc current of 85 A, a pulse bias of -190 V, a duty cycle of 22%, a deposition temperature of 280 °C, a deposition time of 4 h, and a coating thickness of 60 μm.

[0118] Step 4) After the arc ion plating deposition is completed, the single crystal high-temperature alloy substrate containing the coating is subjected to vacuum annealing under vacuum conditions: vacuum gradient heat treatment at 800℃ for 2 hours and 950℃ for 2 hours, with the heating and cooling rates controlled at 1℃ / min, to form a modified MCrAlY coating on the surface of the single crystal high-temperature alloy substrate.

[0119] Comparative Example 1

[0120] Compared to Examples 1-5 above, this comparative example increases the Si content.

[0121] Step 1): The composition is as follows: Cr: 27%, Co: 16%, Al: 13%, Y: 1.6%, Si: 1.5%, with the remainder being Ni, where Si / (Al+Cr) = 37.5 × 10⁻⁶. -3 A master alloy ingot was prepared, and then powder with the same composition was prepared by vacuum atomization.

[0122] Step 2) Grind the single crystal high temperature alloy substrate in sequence using SiC sandpaper of 150#, 240#, 400#, 600# and 800# on the pre-grinding machine to form a sample after grinding out the fresh surface of the single crystal high temperature alloy substrate. Perform wet sandblasting on the sample, and then use acetone and alcohol to ultrasonically treat the sample in sequence.

[0123] Step 3) First, the single-crystal superalloy substrate and furnace cavity are subjected to 12 minutes of air steam treatment to obtain a stable deposition environment. After the sample is loaded into the furnace, the furnace cavity is evacuated to 7 × 10⁻⁶. -3 Pa, temperature rise of 110℃, argon gas is introduced into the vacuum chamber to maintain a pressure of 0.24Pa; then pre-sputter cleaning is performed under the conditions of bias voltage of -700V, duty cycle of 25%, arc current of 60A, sputtering voltage of -18V, sputtering for 4min.

[0124] MCrAlY coating was deposited on a single-crystal high-temperature alloy substrate with the following parameters: target-substrate distance of 250 mm, arc voltage of 25 V, arc current of 77 A, pulse bias of -220 V, duty cycle of 30%, deposition temperature of 230 °C, deposition time of 3 h, and coating thickness of 60 μm.

[0125] Step 4) After the arc ion plating deposition is completed, the single crystal high-temperature alloy substrate containing the coating is subjected to vacuum annealing under vacuum conditions: vacuum gradient heat treatment at 800℃ for 6 hours, followed by air cooling to room temperature, to form a modified MCrAlY coating on the surface of the single crystal high-temperature alloy substrate.

[0126] The chemical compositions of the modified MCrAlY coating of this invention and the conventional MCrAlY coating of Comparative Example 1 are shown in Table 1 below.

[0127] Table 1. Chemical composition (wt.%) of the alloys of the present invention (Examples 1-4) and conventional MCrAlY.

[0128]

[0129]

[0130] Comparison of the cross-sectional microstructure of conventional MCrAlY coatings in Example 1 and Comparative Example 1 of the present invention Figure 1 As shown. From Figure 1 As can be seen, the addition of trace amounts of Si does not change the macroscopic structure of the deposited coating. Both coatings are composed of β phase and γ′ phase, and the coating thickness is about 50 μm. In the preparation state of the modified MCrAlY coating of this invention, Si is mainly dissolved in the β phase of the coating, and the content of the β phase in the coating is relatively high, reaching 55-60%.

[0131] The oxidation weight gain curves of the conventional MCrAlY coatings in Example 2 and Comparative Example 1 of this invention are shown below. Figure 2 As shown, from Figure 2 It can be seen that the weight gain after oxidation at 1000℃ for 200 hours is less than 1.0 mg / cm³. 2 The coating of this invention has higher resistance to high-temperature oxidation than the conventional coating in the comparative example.

[0132] The surface and cross-sectional microstructures of the conventional MCrAlY coatings in Example 3 and Comparative Example 1 after oxidation at 1000℃ for 100 h are as follows: Figure 3 As shown, from Figure 3 As can be seen, the oxide film of the modified MCrAlY coating of this invention has a pinned shape and excellent adhesion to the coating. In contrast, the oxide film in Comparative Example 1 is relatively flat, has poor adhesion to the substrate, and is prone to detachment under thermal loading.

[0133] The weight gain curves of conventional MCrAlY coatings at 900℃ in Example 4 and Comparative Example 1 are shown below. Figure 4 As shown, the coating of this invention exhibits excellent resistance to hot corrosion, with a weight gain of only 0.3 mg / cm³ after 200 hours of hot corrosion at 900℃. 2 It is superior to traditional MCrAlY coatings.

[0134] like Figure 5 The diagram shows the weight gain of the MCrAlY coatings in Examples 5, 4, and Comparative Example 1 after 200 hours of hot corrosion at 900°C. Example 5 shows better performance than Comparative Example 1, but slightly worse than Example 4. Therefore, it can be shown that a / b is within the range of 1.5 × 10⁻⁶. -3 ~3×10 -3 Within the specified range, the modified MCrAlY coating of this invention exhibits superior hot corrosion resistance.

[0135] In summary, this invention provides a modified MCrAlY coating and its preparation method, as well as a single-crystal high-temperature alloy. By employing trace amounts of Si and synergistically controlling the content of elements such as Al and Cr, the prepared modified MCrAlY coating exhibits excellent high-temperature oxidation resistance and significantly improves the anti-scraping ability of the oxide film on the surface of the modified MCrAlY coating, thereby enhancing the inherent strength of the modified MCrAlY coating. It also reduces the tendency of the oxide film on the surface of the modified MCrAlY coating to crack and its detachment ability. After composition optimization, the oxidation resistance of the modified MCrAlY coating is significantly improved, with a 50% reduction in volume weight gain after 200 hours of oxidation at 1140℃. Simultaneously, this modified MCrAlY coating exhibits excellent hot corrosion resistance, with a weight gain of only 0.3 mg / cm³ after 200 hours of hot corrosion at 900℃. 2 The modified MCrAlY coating of this invention is suitable for high-temperature protection of long-life, high-reliability hot-end high-temperature components in the fields of aviation, aerospace, and energy.

[0136] 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 changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A modified MCrAlY coating, characterized in that, The chemical composition of the modified MCrAlY coating, by mass percentage, is as follows: Cr 20~30wt%, Co 10~20wt%, Al 5~15wt%, Y 0.5~1.5wt%, Si 0.05~0.15wt%, with the remainder being Ni; In the modified MCrAlY coating, the mass percentage of Si is a, and the sum of the mass percentages of Al and Cr is b; where a / b = 1.5 × 10⁻⁶. -3 ~3×10 -3 .

2. The modified MCrAlY coating according to claim 1, characterized in that, The chemical composition of the modified MCrAlY coating, by mass percentage, is as follows: Cr 23~28wt%, Co 13~18wt%, Al 8~12wt%, Y 0.8~1.3wt%, Si 0.06~0.12wt%, with the remainder being Ni.

3. A modified MCrAlY coating according to claim 1 or 2, characterized in that, In the case where the modified MCrAlY coating is deposited on the surface of the carrier; The modified MCrAlY coating surface forms a dense oxide film with a pinned morphology to improve the anti-peeling ability of the oxide film on the modified MCrAlY coating surface. And / or, the PB ratio of the oxide film on the surface of the modified MCrAlY coating is 1.5-1.8; And / or, the modified MCrAlY coating contains 55-60% by volume of β phase and 40-45% by volume of γ' phase to improve its high-temperature strength.

4. A method for preparing a modified MCrAlY coating according to any one of claims 1-3, characterized in that, Includes the following steps: Preparation of alloy powder: Prepare master alloy ingots and then prepare alloy powder from the master alloy ingots; Preparation of a coated carrier: The carrier is pretreated, and alloy powder is deposited on the pretreated carrier to obtain a coated carrier; Preparation of modified MCrAlY coating: The carrier containing the coating is heat-treated to form a modified MCrAlY coating on the surface of the carrier.

5. The method for preparing a modified MCrAlY coating according to claim 4, characterized in that, In the preparation of alloy powder, vacuum atomization is used to prepare alloy powder from the master alloy ingot.

6. The method for preparing a modified MCrAlY coating according to claim 5, characterized in that, In the preparation of a carrier containing a coating: the pretreatment includes electrochemical degreasing and activation treatment of the carrier in sequence.

7. The method for preparing a modified MCrAlY coating according to claim 6, characterized in that, Before pretreatment, the carrier is first subjected to surface treatment, which includes grinding, wet sandblasting and ultrasonic treatment in sequence.

8. The method for preparing a modified MCrAlY coating according to claim 4, characterized in that, In the preparation of a carrier containing a coating: the pretreated carrier is pre-sputtered and cleaned.

9. The method for preparing a modified MCrAlY coating according to claim 8, characterized in that, The parameters for pre-sputter cleaning are controlled as follows: The carrier and furnace cavity were subjected to air steam treatment for 10-15 minutes to obtain the deposition environment atmosphere; after the alloy powder was loaded into the furnace, the furnace cavity was evacuated to 7×10⁻⁶. -3 ~8×10 -3 Pa, raise the temperature to 100~120℃, fill the vacuum chamber with inert gas and maintain the gas pressure at 0.23~0.25Pa; perform pre-sputter cleaning under the conditions of bias voltage -600V~-800V, duty cycle of 25~30%, and arc current of 55~65A, controlling the sputtering voltage at -15~-20V and the sputtering time at 3~5min.

10. The method for preparing a modified MCrAlY coating according to claim 4, characterized in that, In the preparation of a coated carrier: alloy powder is deposited onto a pretreated carrier using an arc ion plating deposition technique to obtain a coated carrier.

11. The method for preparing a modified MCrAlY coating according to claim 10, characterized in that, The parameters for arc ion plating deposition technology are controlled as follows: The target-substrate distance is 220mm~280mm, the arc voltage is 20V~25V, the arc current is 70A~90A, the pulse bias voltage is -150~-300V, the duty cycle is 20%~40%, the deposition temperature is 150℃~300℃, the deposition time is 2h-5h, and the coating thickness is 40μm~60μm.

12. The method for preparing a modified MCrAlY coating according to claim 4, characterized in that, In the preparation of the modified MCrAlY coating: vacuum heat treatment was used; The parameters for vacuum heat treatment are controlled as follows: Vacuum gradient heat treatment is adopted, with treatment at 650℃~800℃ for 2~4 hours and at 900℃~1000℃ for 2~4 hours; the heating and cooling rates are controlled at 1-3℃ / min.

13. A material for preparing modified MCrAlY coatings, characterized in that, The chemical composition of the material used to prepare the modified MCrAlY coating, by mass percentage, is as follows: Cr 20~30wt%, Co 10~20wt%, Al 5~15wt%, Y 0.5~1.5wt%, Si 0.05~0.15wt%, with the remainder being Ni; Wherein, the mass percentage of Si is a, and the sum of the mass percentages of Al and Cr is b; where a / b = 1.5 × 10⁻⁶. -3 ~3×10 -3 .

14. A single-crystal high-temperature alloy, characterized in that, The single-crystal superalloy includes a single-crystal superalloy substrate and a modified MCrAlY coating deposited on the single-crystal superalloy substrate; wherein the modified MCrAlY coating is the modified MCrAlY coating as described in claim 1 or 2.

15. The single-crystal high-temperature alloy according to claim 14, characterized in that, The single-crystal high-temperature alloy matrix is ​​a single-crystal high-temperature alloy blade.

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