阅读说明：本技术 一种用于单晶高温合金低扩散单相铂铝涂层的制备方法 (Preparation method of single-phase low-diffusion platinum-aluminum coating for single-crystal high-temperature alloy ) 是由 鲍泽斌 刘贺 余春堂 朱圣龙 王成 辛丽 于 2019-03-01 设计创作，主要内容包括：本发明涉及单晶高温合金领域,具体为一种用于单晶高温合金低扩散单相铂铝涂层的制备方法。该方法包括以下步骤：(1)对金属基体预磨、喷砂及除油等表面处理；在基体上采用电镀法电镀Ni-Re层；(2)采用碱性镀铂液进行镀铂；(3)扩散退火；(4)采用包埋、料浆及CVD化学气相沉积法渗铝,获得高温防护单相铝化物涂层。本发明在单相铂铝涂层与镍基单晶基体间生成以Re为主的致密扩散障,为了提高铂改性铝化物涂层的抗高温氧化及热腐蚀综合性能,同时阻碍或减缓涂层与基体之间的元素互扩散。该方法制备过程简单,可控性高,成本低廉,Re元素含量可控,镀层适用范围广,普适性强。(The invention relates to the field of single crystal high temperature alloys, in particular to a preparation method of a single-phase low-diffusion platinum-aluminum coating for a single crystal high temperature alloy. The method comprises the following steps: (1) pre-grinding, sand blasting, oil removing and other surface treatments of the metal matrix; electroplating a Ni-Re layer on the substrate by an electroplating method; (2) platinizing by using an alkaline platinizing liquid; (3) diffusion annealing; (4) embedding, slurry and Chemical Vapor Deposition (CVD) aluminizing are adopted to obtain the high-temperature protection single-phase aluminide coating. The invention generates a dense diffusion barrier mainly based on Re between a single-phase platinum-aluminum coating and a nickel-based single crystal substrate, aims to improve the comprehensive performance of high-temperature oxidation resistance and hot corrosion resistance of the platinum modified aluminide coating, and simultaneously hinders or slows down the mutual diffusion of elements between the coating and the substrate. The method has the advantages of simple preparation process, high controllability, low cost, controllable content of Re element, wide application range of the plating layer and strong universality.)

1. A preparation method of a single-phase low-diffusion platinum-aluminum coating for a single-crystal high-temperature alloy is characterized by comprising the following steps:

(1) the surface treatment method comprises the following steps: pre-grinding and sand blasting the matrix, and then removing oil by using an alkali washing and ultrasonic treatment method;

(2) and (3) carrying out Ni-Re electroplating on the treated substrate: the electroplating solution is an aqueous solution prepared from nickel sulfate, sodium chloride, boric acid, sodium sulfate, potassium perrhenate and sodium dodecyl sulfate, the pH value is maintained between 4 and 5.5, the prepared solution is placed in a water bath at the temperature of between 40 and 65 ℃, and the current density is 1 to 5A/dm²Electroplating by using a pure nickel plate as an anode, wherein the thickness of the electroplated Ni-Re layer is 2-10 mu m;

(3) and (3) carrying out platinum plating on the prepared Ni-Re plating layer: an alkaline platinizing process is adopted, the pH value is maintained between 7 and 11 during platinizing, and the temperature is controlled between 60 and 90 ℃ during electroplating; the current density is 1-5A/dm²Electroplating by taking pure platinum or platinum-plated titanium mesh as an anode, wherein the thickness of the plated Pt layer is 3-8 mu m;

(4) annealing the electroplated coating in a vacuum annealing furnace with the air pressure of less than 6 × 10^-3Pa, the heating rate is below 10 ℃/min during annealing; in the annealing process, firstly, keeping the temperature of 400-700 ℃ for 2-4 h to remove residual hydrogen on the coating and prevent the occurrence of a bulging phenomenon; after dehydrogenation, continuously heating to 1000-1100 ℃, preserving heat for 1-4 h, and cooling to room temperature;

(5) and after diffusion annealing, aluminizing by adopting chemical vapor deposition or a non-contact vapor phase method to obtain the low-diffusion NiRePtAl coating containing the Re diffusion barrier.

2. The method for preparing a single-phase platinum-aluminum coating with low diffusion for single-crystal superalloy according to claim 1, wherein in the step (1), the substrate is a Ni-based single-crystal superalloy and comprises: second and third generations of nickel-based single crystal or single crystal intermetallic compound.

3. The method for preparing a single-phase platinum-aluminum coating with low diffusion for single-crystal superalloy according to claim 1, wherein in the step (2), the component content of the electroplating solution is in the following range: 100-300 g/L of nickel sulfate, 10-30 g/L of sodium chloride, 20-40 g/L of boric acid, 20-100 g/L of sodium sulfate, 3-30 g/L of potassium perrhenate, 0.05-0.2 g/L of sodium dodecyl sulfate and the balance of water.

4. The method for preparing a single-phase platinum-aluminum coating with low diffusion for single-crystal superalloy according to claim 1, wherein the method for preparing the single-phase NiRePtAl coating with low diffusion is obtained, the coating is divided into three parts, the outer layer is a single-phase beta- (Ni, Pt) Al coating, the middle layer is a Re diffusion resistance layer, and the inner layer is a mutual diffusion region, wherein: the Re diffusion-resistant layer is enriched at the interface of the single-phase beta- (Ni, Pt) Al coating and the inter-diffusion region, and the inter-diffusion region is enriched at the interface of the single crystal substrate.

5. The preparation method of a single-phase platinum-aluminum coating for low diffusion of single-crystal high-temperature alloy according to claim 4, characterized in that the thickness range of the single-phase beta- (Ni, Pt) Al coating is 20-30 μm, the thickness range of the middle layer is Re diffusion-resistant layer is 5-10 μm, and the thickness range of the inner layer is mutual diffusion region is 10-30 μm.

Technical Field

The invention relates to the field of single crystal high temperature alloys, in particular to a preparation method of a single-phase low-diffusion platinum-aluminum coating for a single crystal high temperature alloy.

Background

The single crystal high temperature alloy eliminates crystal boundary, obviously reduces crystal boundary strengthening elements for reducing melting point, greatly improves the initial melting temperature compared with casting and directional solidification high temperature alloy, can carry out solution treatment in a higher temperature range, and is a key material for the blade of the advanced power propulsion system aeroengine. The content of Al in the single crystal high-temperature alloy is generally lower than 7 wt%, the single crystal high-temperature alloy is not enough to be selectively oxidized to generate a single protective aluminum oxide film, the high-temperature oxidation corrosion resistance is poor, and a high-temperature protective coating needs to be applied for protection before service. The current high temperature protective coating mainly comprises: simple aluminide coating, M (M ═ Ni, Co or Ni-Co) CrAlY coating and platinum-aluminum (mainly single-phase beta- (Ni, Pt) Al) coating, wherein the platinum-aluminum coating has more excellent comprehensive performance of high-temperature oxidation and thermal corrosion resistance than the former two. The element Pt can promote the selective oxidation of Al, reduce the effect of harmful elements such as S and the like, and simultaneously can improve the adhesion property of a protective alumina film generated by a coating, so that the oxidation resistance is excellent. However, as with other high temperature protective coatings, the platinum modified aluminide coating can improve the oxidation resistance of the nickel-based single crystal superalloy, and also can cause the mechanical properties (high temperature endurance, fatigue and the like) of the base single crystal alloy to be obviously reduced due to the mutual diffusion of elements between the coating and the base. Therefore, in order to ensure the excellent high-temperature oxidation resistance of the platinum-aluminum coating and simultaneously reduce the mechanical property of the nickel-based single crystal superalloy, the problem of mutual diffusion of elements between the platinum-aluminum coating and the nickel-based single crystal superalloy needs to be solved, and the service life of a nickel-based single crystal superalloy component (such as an aircraft engine blade) is prolonged in a mode of slowing down the degradation rate of the coating. Refractory elements such as: re, Ta, W, etc., can reduce interdiffusion between the coating and the substrate.

The metal diffusion barrier can also be prepared by a method of depositing pure metal Re on a substrate by using an EB-PVD (electron beam physical vapor deposition) method, but the method needs large EB-PVD equipment and is high in cost.

Disclosure of Invention

The invention aims to provide a preparation method of a single-phase platinum-aluminum coating for low diffusion of a single-phase high-temperature alloy, which is characterized in that a dense diffusion barrier mainly containing Re is generated between the single-phase platinum-aluminum coating and a nickel-based single-crystal substrate, so that the comprehensive performance of high-temperature oxidation resistance and hot corrosion resistance of a platinum modified aluminide coating is improved, and the mutual diffusion of elements between the coating and the substrate is hindered or slowed down.

The technical scheme of the invention is as follows:

a preparation method of a single-phase low-diffusion platinum-aluminum coating for a single-crystal high-temperature alloy comprises the following steps:

(1) the surface treatment method comprises the following steps: pre-grinding and sand blasting the matrix, and then removing oil by using an alkali washing and ultrasonic treatment method;

(2) and (3) carrying out Ni-Re electroplating on the treated substrate: the electroplating solution is an aqueous solution prepared from nickel sulfate, sodium chloride, boric acid, sodium sulfate, potassium perrhenate and sodium dodecyl sulfate, the pH value is maintained between 4 and 5.5, the prepared solution is placed in a water bath at the temperature of between 40 and 65 ℃, and the current density is 1 to 5A/dm²Electroplating by using a pure nickel plate as an anode, wherein the thickness of the electroplated Ni-Re layer is 2-10 mu m;

(3) and (3) carrying out platinum plating on the prepared Ni-Re plating layer: an alkaline platinizing process is adopted, the pH value is maintained between 7 and 11 during platinizing, and the temperature is controlled between 60 and 90 ℃ during electroplating; the current density is 1-5A/dm²Electroplating by taking pure platinum or platinum-plated titanium mesh as an anode, wherein the thickness of the plated Pt layer is 3-8 mu m;

(4) annealing the electroplated coating in a vacuum annealing furnace with the air pressure of less than 6 × 10^-3Pa, the heating rate is below 10 ℃/min during annealing; in the annealing process, firstly, keeping the temperature of 400-700 ℃ for 2-4 h to remove residual hydrogen on the coating and prevent the occurrence of a bulging phenomenon; after dehydrogenation, continuously heating to 1000-1100 ℃, preserving heat for 1-4 h, and cooling to room temperature;

(5) and after diffusion annealing, aluminizing by adopting chemical vapor deposition or a non-contact vapor phase method to obtain the low-diffusion NiRePtAl coating containing the Re diffusion barrier.

The preparation method of the single-phase platinum-aluminum coating for low diffusion of the single-crystal high-temperature alloy comprises the following steps of (1), wherein a matrix is a Ni-based single-crystal high-temperature alloy, and the preparation method comprises the following steps: second and third generations of nickel-based single crystal or single crystal intermetallic compound.

According to the preparation method for the single-phase low-diffusion platinum-aluminum coating of the single-crystal high-temperature alloy, in the step (2), the component content range of the electroplating solution is as follows: 100-300 g/L of nickel sulfate, 10-30 g/L of sodium chloride, 20-40 g/L of boric acid, 20-100 g/L of sodium sulfate, 3-30 g/L of potassium perrhenate, 0.05-0.2 g/L of sodium dodecyl sulfate and the balance of water.

The preparation method for the single-phase low-diffusion platinum-aluminum coating of the single-crystal high-temperature alloy is characterized in that the low-diffusion single-phase NiRePtAl coating is obtained by the preparation method and is divided into three parts, the outer layer is a single-phase beta- (Ni, Pt) Al coating, the middle layer is a Re diffusion resistance layer, and the inner layer is a mutual diffusion region, wherein: the Re diffusion-resistant layer is enriched at the interface of the single-phase beta- (Ni, Pt) Al coating and the inter-diffusion region, and the inter-diffusion region is enriched at the interface of the single crystal substrate.

According to the preparation method of the single-phase platinum-aluminum coating for the low diffusion of the single-crystal high-temperature alloy, the thickness range of the single-phase beta- (Ni, Pt) Al coating is 20-30 mu m, the thickness range of the middle layer which is the Re resistance diffusion layer is 5-10 mu m, and the thickness range of the inner layer which is the mutual diffusion region is 10-30 mu m.

The design idea of the invention is as follows:

the invention develops an advanced high-temperature protective coating which inhibits interdiffusion with a matrix and has slower oxidation weight gain at high temperature. The melting point of the rhenium-based diffusion barrier is 2362 ℃, the rhenium-based diffusion barrier is stable at high temperature, and the solubility of aluminum in the rhenium-based diffusion barrier is low. The rhenium-based diffusion barrier is introduced into the single-phase platinum-aluminum coating and the matrix, and can play a role in inhibiting mutual diffusion.

The invention has the following advantages and beneficial effects:

1. the preparation process is simple and the controllability is high. The method deposits the Ni-Re layer in an electroplating way, does not need EB-PVD and other large-scale vacuum equipment, can be used for depositing parts with complex shapes, and has low cost.

2. Re in the electroplating formula is provided by Re-containing salt in the plating solution, the content of the Re in the coating is controllable, and the thickness of the coating is controllable.

Drawings

FIG. 1 shows the cross-sectional morphology of the Ni-Re plating.

FIG. 2 is a cross-sectional view of the Ni-Re plus Pt plating before (a) and after (b) annealing.

Figure 3 is the coating XRD results after aluminizing. In the figure, the abscissa 2theta represents the diffraction angle (deg.) and the ordinate Intensity represents the relative Intensity (a.u deg.).

FIG. 4 is a cross-sectional profile of NiRePtAl/N5.

FIG. 5 is a cross-sectional profile of NiRePtAl/IC 21.

FIG. 6 is a graph of the high temperature oxidation kinetics of example 1 and a photograph of the micro cross-sectional profile of the interdiffusion zone under the oxidized coating. Wherein, (a) is a high-temperature oxidation kinetic curve, (b) is a micro-morphology picture of the cross section of the interdiffusion region after a common (Ni, Pt) Al coating is oxidized for 300h at 1100 ℃, and (c) is a micro-morphology picture of the cross section of the interdiffusion region after the NiRePtAl coating is oxidized for 300h at 1100 ℃.

FIG. 7 is a graph of the high temperature oxidation kinetics and a photograph of the interdiffusion micro cross-sectional topography after oxidation for example 2. Wherein, (a) is a high-temperature oxidation kinetic curve, (b) is a microscopic section morphology picture of a common (Ni, Pt) Al coating oxidized at 1100 ℃ for 200h, and (c) is a microscopic section morphology picture of a NiRePtAl coating oxidized at 1100 ℃ for 200 h.

Detailed Description

In the specific implementation process, the preparation method of the low-diffusion single-phase platinum-aluminum coating for the nickel-based single-crystal superalloy comprises the following steps of:

(1) the surface treatment method comprises the following steps: pre-grinding and sand blasting the matrix, and then removing oil by using an alkali washing and ultrasonic treatment method;

(2) electroplating Ni-Re on the treated substrate: the electroplating solution is an aqueous solution prepared from nickel sulfate, sodium chloride, boric acid, sodium sulfate, potassium perrhenate and sodium dodecyl sulfate, the pH value is maintained between 5 and 5.5 during electroplating, and the prepared solution is put in a water bath 40 to 65 ℃ and a current density of 1 to 5A/dm²And electroplating by using a pure nickel plate as an anode, wherein the thickness of the electroplated Ni-Re layer is 2-10 mu m.

(3) And (3) carrying out platinum plating on the prepared Ni-Re plating layer: the alkaline platinizing process is adopted, the pH value is maintained between 7 and 11 during platinizing, and the temperature is controlled between 60 and 90 ℃ during electroplating. The current density is 1-5A/dm²Electroplating by taking pure platinum or platinum-plated titanium mesh as an anode, wherein the thickness of the plated Pt layer is 3-8 mu m;

(4) annealing the electroplated coating in a vacuum annealing furnace with the air pressure of less than 6 × 10^-3Pa, the heating rate is below 10 ℃/min during annealing; in the annealing process, firstly, keeping the temperature of 400-700 ℃ for 2-4 h to remove residual hydrogen on the coating and prevent the occurrence of a bulging phenomenon; after dehydrogenation, continuously heating to 1000-1100 ℃, preserving heat for 1-4 h, and cooling to room temperature;

(5) and after diffusion annealing, aluminizing by adopting an embedding, slurry, Chemical Vapor Deposition (CVD) or non-contact gas phase (Above-pack) method to obtain the low-diffusion NiRePtAl coating containing the Re diffusion barrier.

The present invention will be described in further detail below with reference to examples.