CN103103473A - Method for preparing erosion resistive and high-temperature abradable seal coating based on hot spraying - Google Patents

Abstract

The invention discloses a method for preparing an erosion-resistant high-temperature wear-resistant sealing coating based on thermal spraying. The liquid-solid two-phase particles melted on the surface collide and deposit on the surface of a substrate, and the surface temperature of the substrate is controlled so that the liquid-solid two-phase particles When the liquid part of the liquid solidifies, a phase structure with high thermal stability is formed, and an effective combination is formed between the surface of the matrix and the solid phase particles in the liquid-solid two-phase particles; the subsequent liquid-solid two-phase particles are deposited on the surface of the deposited particles, and gradually accumulate to form A sedimentary layer with a pore structure; the filling powder whose particle size is smaller than the pore structure of the sedimentary layer or the precursor of the filling powder is filled into the connected pores of the sedimentary layer through the state of solid phase or suspension to obtain erosion resistance and high temperature. Abradable seal coat. The sealing coating material prepared by the method can be selected in a wide range, the pores are evenly distributed in the coating, the cost is low, and the method is simple and convenient.

Description

A method for preparing erosion-resistant high-temperature abradable sealing coating based on thermal spraying

technical field

The invention belongs to the technical field of sealing coating preparation, and relates to a method for preparing an erosion-resistant, high-temperature, wearable sealing coating based on thermal spraying.

Background technique

With the continuous development and progress of the aerospace industry, reducing the gap between moving and static parts has become one of the important means to obtain high thrust, high efficiency and low fuel consumption when designing and manufacturing high-performance engines. However, in the use of blades, thermal deformation and vibration will cause the overall displacement of the parts, the high-speed rotation of the engine rotor will cause the blades to elongate, and certain tolerances and assembly deviations must be reserved during the processing of parts. Leave some space. Therefore, the simple and effective method of sealing coating must be used to reduce the gap.

Foreign research on abradable sealing coatings started in the 1950s and was practically applied in the late 1960s. At present, the commonly used abradable sealing coating is mainly composed of metal matrix composite materials. Composite materials include metallic phases, self-lubricating nonmetals and many pores. The main materials used are NiAl, AlSi, NiCrAl, NiCrAlY and so on. The main advantage of this coating is that it has high bonding strength with the substrate, but it has disadvantages such as poor abradability, easy melting and adhesion to blades when used at high temperature, and thermal deformation leading to coating failure. Therefore, in order to improve the properties of this coating, a soft phase (which can also be used as a lubricating phase) is usually added to it, such as h-BN, graphite, diatomaceous earth, polyester, etc. The main advantages of adding a soft phase are to adjust the hardness of the coating, improve the lubricity of the coating and the blade, reduce the wear of the blade, improve the abradability of the coating, and prevent the adhesion of the coating and the blade. This kind of coating, such as Ni-graphite, AlSi-polyester, NiCrAl-boron nitride, which has a certain porosity, is superior to the former in terms of heat resistance and thermal shock resistance, but this coating also has The disadvantages of unsatisfactory combination strength and air erosion resistance.

Modern aero-engines use a compressor to increase the pressure and temperature of the air, so that the fuel can be fully burned, which is one of the main methods to improve the power and efficiency of the engine. Therefore, the working temperature of the compressor has reached above 1000°C. Since most of the previous coatings were used at a temperature lower than 850°C, it is obvious that they cannot meet the requirements of the engine. Therefore, it is necessary to research and develop coatings that can withstand higher temperatures and have superior impact resistance. Corrosion-resistant sealing coating preparation method.

Contents of the invention

The problem to be solved by the present invention is to provide a method for preparing an erosion-resistant, high-temperature, wearable sealing coating based on thermal spraying. The sealing coating material prepared by this method can be selected in a wide range, and the pores are evenly distributed in the coating, and the cost is low. low and simple method.

The present invention is achieved through the following technical solutions:

A method for preparing an erosion-resistant, high-temperature, abradable sealing coating based on thermal spraying, comprising the following operations:

1) The liquid-solid two-phase particles melted on the surface collide and deposit on the surface of the substrate, and the temperature of the substrate surface is controlled so that the liquid part of the liquid-solid two-phase particles solidifies to form a phase structure with high thermal stability. The surface of the substrate and the liquid-solid two-phase The solid phase particles in the particles form an effective combination; the subsequent liquid-solid two-phase particles are deposited on the surface of the deposited particles, and gradually accumulate to form a sedimentary layer with a pore structure;

2) Filling powder with a particle size smaller than the pore structure of the sediment layer or the precursor of the filler powder is filled into the connected pores of the sediment layer through the state of solid phase or suspension to obtain a seal with erosion resistance and high temperature abrasion resistance coating.

The liquid-solid two-phase particles are hollow particles and/or solid particles, and their materials are preferably alumina-based or zirconia-based ceramics with high-temperature structural stability.

The solid phase part in the liquid-solid two-phase particles has a dense local organizational structure.

When the liquid-solid two-phase particles collide and deposit on the surface of the substrate, the deposition angle changes continuously due to the microscopic randomness of the collision deposition position.

Before the liquid-solid two-phase particles are deposited, the surface temperature of the substrate exceeds the temperature at which a stable structure can be formed after the liquid phase is solidified, and the liquid phase material in the particle bonding area forms a high-temperature thermally stable phase structure.

The formed sealing coating is a porous layered structure formed by lamination of flat particles after phase transition of liquid-solid two-phase particles through mechanical interlocking and micro-area metallurgical bonding.

The particles are spherical or nearly spherical particles with a particle diameter of 30-100 μm.

The flame spraying uses oxygen to feed powder, the combustible gas flow rate is adjustable, the spraying distance is adjustable, the flame is a micro-oxidizing flame, and the compressed air flow rate is 1000-1500L/h;

The porosity of the sealing coating is adjusted by adjusting the flow rate of combustible gas; the surface morphology and porosity of the sealing coating are adjusted by adjusting the distance of spraying.

The filling powder is the same or different ceramic material as that deposited by spraying, preferably an alumina-based or zirconia-based ceramic material with excellent erosion resistance.

Before the substrate is deposited, a bonding layer is prepared on the surface of the substrate, preferably a MCrAlY superalloy material, where M refers to Ni or Co or an alloy of the two, and the MCrAlY superalloy material can also be added with Ta and Re elements.

Compared with the prior art, the present invention has the following beneficial technical effects:

The method for preparing an erosion-resistant, high-temperature, abradable sealing coating based on thermal spraying provided by the present invention is to prepare a thermal spraying coating through a thermal spraying method to form a sealing coating. The thermal spray coating formed by traditional thermal spraying is a porous layered structure formed by stacking flat particles in a mechanically interlocking and micro-metallurgical combination. Such a structure has a high level of internal stress. Since the thickness of the flat particles is only on the order of microns, when the particles are eroded on the surface of the coating, the surface flat particles not only undergo erosion and wear by micro-cutting, but also bear the impact of the longitudinal velocity component of the particles on the flat particles. The pores, especially the unbonded interface area, will act as prefabricated cracks to promote the cracking and shedding of the whole or even a few flat particles, thus reducing the erosion resistance of the coating.

The method for preparing erosion-resistant, high-temperature, abradable sealing coatings based on thermal spraying provided by the present invention has a structure of tens or even hundreds of microns of spherical or near-spherical particles stacked and connected, and the limited combination between particles allows the coating to have wearable properties. Abrasion resistance; while larger-sized particles with a diameter of tens of microns will have significant erosion resistance characteristics, and the probability of falling off several layers of particles from the particle joint will be significantly reduced, so it has superior erosion resistance Characteristics; again, through process control, the deposited material forms a stable phase structure at high temperature, thereby eliminating the problem that the phase change of the metastable phase affects the life or performance of the coating or even fails when it is served at high temperature.

Description of drawings

Figure 1: Photo of the original powder morphology involved in Example 1 of the present invention, where (a) is the crushed Al ₂ O ₃ powder, and (b) is the Al ₂ O ₃ powder after plasma flame spheroidization treatment.

Figure 2: Typical coating morphology prepared by using the Al ₂ O ₃ powder in Figure 1(b) at an acetylene flow rate of 300L/h and a spraying distance of 20mm, (a) is the surface morphology, (b) is the porous deposition The cross-sectional morphology after the layer is impregnated with binder (glue).

Figure 3: The overall cross-sectional structure of the coating prepared by using the Al ₂ O ₃ powder in Figure 1(b) at a spraying distance of 40mm, (a) the flow rate of acetylene is 200L/h, (b) the flow rate of acetylene is 300L/h , (c) The flow rate of acetylene is 400L/h.

Figure 4: Al ₂ O ₃ coating deposited by flame spraying of Al ₂ O ₃ powder in Figure 1(b) at an acetylene flow rate of 400L/h, (a) surface morphology when the spraying distance is 20mm, (b) spraying distance The cross-sectional morphology after glue-seeding treatment when the distance is 20mm; (c) the surface morphology when the spraying distance is 30mm, (d) the cross-sectional morphology after the glue-penetrating treatment when the spraying distance is 30mm; (e) when the spraying distance is 40mm (f) The cross-sectional morphology after the spraying distance is 40mm; (g) The surface morphology when the spraying distance is 60mm, (h) The cross-sectional shape after the spraying distance is 60mm appearance.

Figure 5: The coating deposited by flame spraying YSZ powder, where (a) is YSZ powder, (b) is the surface morphology of the coating obtained by spraying, and (c) is the cross-sectional morphology of the coating obtained by spraying.

Detailed ways

The method for preparing erosion-resistant, high-temperature, abradable sealing coatings based on thermal spraying provided by the present invention has a structure of tens or even hundreds of microns of spherical or near-spherical particles stacked and connected, and the limited combination between particles allows the coating to have wearable properties. Abrasiveness; and larger size particles, will have significant erosion resistance properties. The present invention will be further described in detail below in conjunction with specific embodiments, which are explanations of the present invention rather than limitations.

A method for preparing an erosion-resistant, high-temperature, abradable sealing coating based on thermal spraying, comprising the following operations:

1) The liquid-solid two-phase particles melted on the surface collide and deposit on the surface of the substrate, and the temperature of the substrate surface is controlled so that the liquid part of the liquid-solid two-phase particles solidifies to form a phase structure with high thermal stability. The surface of the substrate and the liquid-solid two-phase The solid phase particles in the particles form an effective combination; the subsequent liquid-solid two-phase particles are deposited on the surface of the deposited particles, and gradually accumulate to form a sedimentary layer with a pore structure;

2) Filling powder with a particle size smaller than the pore structure of the sediment layer or the precursor of the filler powder is filled into the connected pores of the sediment layer through the state of solid phase or suspension to obtain a seal with erosion resistance and high temperature abrasion resistance coating.

Further, the liquid-solid two-phase particles are hollow particles and/or solid particles. Hollow particles can form a large number of closed pores in the coating. For the thermal shock resistance and thermal stress relief of the coating, the performance is better than that of solid particles. The material type of liquid-solid two-phase particles is preferably alumina-based or zirconia-based with high temperature structure stability. ceramics.

The solid phase part in the liquid-solid two-phase particles has a dense local organization structure, and the structure organization can play the role of anti-erosion.

When the liquid-solid two-phase particles collide and deposit on the surface of the substrate, the deposition angle is constantly changed due to the microscopic randomness of the collision deposition position, so as to reduce the size of the solid part of the particles larger than the powder size or its solid phase due to the shielding effect during deposition. Part of the large-scale connected pores, so as to prepare a coating with uniform distribution of pores, which is beneficial to the protection of the blade and reduces the risk of large-scale peeling off of the coating.

Before the liquid-solid two-phase particles are deposited, the surface temperature of the substrate exceeds the temperature at which a stable structure can be formed after the liquid phase is solidified, and the liquid phase material in the particle bonding area forms a high-temperature thermally stable phase structure.

The formed sealing coating is a porous layered structure formed by lamination of flat particles after phase transition of liquid-solid two-phase particles through mechanical interlocking and micro-area metallurgical bonding.

The metal particles are spherical or nearly spherical particles with a diameter of 30-100 μm.

The flame spraying uses oxygen to feed powder, the combustible gas flow rate is adjustable, the spraying distance is adjustable, the flame is a micro-oxidizing flame, and the compressed air flow rate is 1000-1500 L/h. Adjust the porosity of the sealing coating by adjusting the flow of combustible gas; adjust the surface morphology and porosity of the sealing coating by adjusting the distance of spraying.

The filling powder is the same or different ceramic material as the material deposited by spraying, preferably an alumina-based or zirconia-based ceramic material with excellent erosion resistance; the presence of through holes is reduced by filling smaller particles, thereby Improve the airtightness of the coating, and further effectively improve the engine efficiency.

Before the substrate is deposited, a bonding layer is prepared on the surface of the substrate, preferably a MCrAlY superalloy material, where M refers to Ni or Co or an alloy of the two, and the MCrAlY superalloy material can also be added with Ta and Re elements.

Specific examples are given below.

Example 1:

的Al₂O₃基体片(将喷涂粉末压制后烧结而成)预热至1200℃的条件下进行喷涂，用红外测温仪(RAYRPM30L3U,Raytek，USA)监测基体前面温度。所得表面和断面形貌如图2所示，形成了α-Al₂O₃这种稳定的相结构。Taking Al ₂ O ₃ powder by flame spraying as an example, part of the powder is hollow, and the particle size of the powder is 40-50 μm, as shown in Figure 1. The flame gun is operated by the manipulator, and the speed of the gun is 30mm/s. Spraying uses oxygen for powder feeding, the flow rate of acetylene is 300L/h, the spraying distance is 20mm, the flame is a micro-oxidizing flame, and the flow rate of compressed air is 1500L/h. Will

The Al ₂ O ₃ substrate sheet (compressed and sintered by spraying powder) was preheated to 1200°C for spraying, and the temperature in front of the substrate was monitored by an infrared thermometer (RAYRPM30L3U, Raytek, USA). The resulting surface and cross-sectional morphology are shown in Figure 2, forming a stable phase structure of α-Al ₂ O ₃ .

Example 2:

Taking Al ₂ O ₃ powder by flame spraying as an example, part of the powder is hollow, and the particle size of the powder is 40-50 μm, as shown in Figure 1. The flame gun is operated by the manipulator, and the speed of the gun is 30mm/s. Spraying uses oxygen for powder feeding, acetylene flow rate is 200L/h, 300L/h, 400L/h respectively, spraying distance is 40mm, flame is micro-oxidation flame, and compressed air flow rate is 1500L/h. The cross-sectional morphology is shown in Figure 3. It can be seen from the figure that with the increase of the acetylene flow rate, the open pores of the coating gradually decrease, and the closed pores that meet the requirements increase, and with the increase of the flow rate, the size of the closed pores decreases. It can be seen that by adjusting the flow rate of acetylene, a sealing coating with good performance required by the required porosity can be obtained.

Example 3:

Taking Al ₂ O ₃ powder by flame spraying as an example, part of the powder is hollow, and the particle size of the powder is 40-50 μm, as shown in Figure 1. The flame gun is operated by the manipulator, and the speed of the gun is 30mm/s. Spraying uses oxygen for powder feeding, the acetylene flow rate is 400L/h, the spraying distance is 20mm, 30mm, 40mm, 60mm respectively, the flame is a micro-oxidation flame, and the compressed air flow rate is 1500L/h. The obtained surface morphology and cross-sectional morphology are shown in Fig. 4. The coating particles shown in Figure 4(g) and Figure 4(h) are completely melted, and the coating has low porosity and is too dense, which does not meet the actual requirements of the sealing coating. It can be seen from the figure that the sealing coatings with different surface morphology and internal porosity can be obtained by adjusting the spraying distance. If the deposition surface temperature is further controlled to be above 1000°C in this process, the alumina at the particle junction is not a high-temperature quasi-stable phase γ-Al ₂ O ₃ , but a high-temperature stable α-Al ₂ O ₃ , so It avoids the stress and strain caused by the phase transition and the damage of the joint part during high temperature service, and can greatly improve the stability and life of the sealing coating.

Example 4:

Taking flame spraying YSZ powder as an example, the powder is hollow and the particle size is 70-100 μm, as shown in Figure 5(a). The flame gun is operated by the manipulator, and the speed of the gun is 30mm/s. Spraying uses oxygen for powder feeding, the flow rate of acetylene is 360L/h, the spraying distance is 40mm, the flame is a micro-oxidizing flame, and the flow rate of compressed air is 1500L/h. The obtained surface morphology and cross-sectional morphology are shown in Fig. 5(b) and Fig. 5(c). Through the melting of the surface layer, the liquid phase forms a strong connection with the deposited hollow particles. The porosity of the coating can be further adjusted by the proportion of the volume of the hollow part of the hollow powder in the powder in addition to being regulated by the spraying process, so as to obtain sealing coatings with different porosities.

The above content is a further detailed description of the present invention in conjunction with specific preferred embodiments. It cannot be determined that the specific embodiments of the present invention are limited thereto. Under the circumstances, some simple deduction or replacement can also be made, all of which should be regarded as belonging to the scope of patent protection determined by the submitted claims of the present invention.

Claims (10)

1. a method for preparing the erosion resistance high-temperature abradable seal coating based on thermospray, is characterized in that, comprises following operation:

1) with the liquid-solid two-phase particle collision of surface melting and be deposited on matrix surface, control matrix surface temperature forms when the liquid part in the liquid-solid two-phase particle is solidified has the phase structure of high thermal stability, forms effective combination between the solid phase particles in matrix surface and liquid-solid two-phase particle; Follow-up liquid-solid two-phase particle deposition is to the particle surface that has deposited, and cumulative formation has the settled layer of pore texture gradually;

2) with particle size less than the powder filler of settled layer pore texture or the presoma of this powder filler, the state by solid phase or suspension is filled in the open pore of settled layer, obtains to have the seal coating of erosion resistance, high-temperature abrasive.

2. the method for preparing the erosion resistance high-temperature abradable seal coating based on thermospray as claimed in claim 1, it is characterized in that, described liquid-solid two-phase particle is hollow bead and/or full particle, and its material is the stable alumina base of thermal structure or zirconia-based ceramics.

3. the method for preparing the erosion resistance high-temperature abradable seal coating based on thermospray as claimed in claim 1, is characterized in that, the solid phase in described liquid-solid two-phase particle partly has fine and close local organization structure.

4. the method for preparing the erosion resistance high-temperature abradable seal coating based on thermospray as claimed in claim 1, it is characterized in that, described liquid-solid two-phase particle collision and when being deposited on matrix surface the microcosmic randomness because of the Collision deposition position constantly change angle of deposit.

5. the method for preparing the erosion resistance high-temperature abradable seal coating based on thermospray as claimed in claim 1, is characterized in that, before the liquid-solid two-phase particle deposition, described matrix surface temperature surpasses the temperature that can form rock steady structure after liquid phase is solidified; The liquid phase material of particle calmodulin binding domain CaM forms the phase structure of high-temperature thermal stability.

6. the method for preparing the erosion resistance high-temperature abradable seal coating based on thermospray as claimed in claim 1, it is characterized in that, formed seal coating is porous laminated structure chimeric with machinery by the flat particle after the phase transformation of liquid-solid two-phase particle and that the stacked accumulation of the mode microcell metallurgical binding forms.

7. the method for preparing the erosion resistance high-temperature abradable seal coating based on thermospray as claimed in claim 1, is characterized in that, described particle is that particle diameter is the spherical or subsphaeroidal particle of 30～100 μ m.

8. the method for preparing the erosion resistance high-temperature abradable seal coating based on thermospray as claimed in claim 1, it is characterized in that, described flame plating is to carry out powder feeding with oxygen, the inflammable gas flow is adjustable, spray distance is adjustable, flame is the low-level oxidation flame, and compressed air require is 1000～1500L/h;

The porosity of regulating seal coating by the flow of regulating inflammable gas; Surface topography and porosity that the distance that sprays by adjusting is regulated seal coating.

9. the method for preparing the erosion resistance high-temperature abradable seal coating based on thermospray as claimed in claim 1, is characterized in that, described powder filler is the stupalith identical or different with spray deposited material;

Described powder filler is alumina base or the zirconia-based ceramics material with erosive wear resistance.

10. the method for preparing the erosion resistance high-temperature abradable seal coating based on thermospray as claimed in claim 1, is characterized in that, before the matrix deposition, also prepares one deck key coat MCrAlY at matrix surface, and wherein, M is Ni, Co or both alloys.

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