A vacuum infiltration sintering method of adaptive gradient tip wear-resistant seal coating

Abstract

A vacuum melt-infiltration sintering method for an adaptive gradient blade tip wear-resistant sealing coating is disclosed. The method involves melting a low-melting-point alloy (IV) under vacuum conditions, allowing the melt to infiltrate through surface-metallized nano / micro-ceramic particles (III). These nano-ceramic particles, under the influence of gravity, capillary force, and fluid viscosity, flow through infiltration channels formed between the powder particles into high-melting-point powder (I). The content of nano-ceramic particles gradually decreases with increasing depth, while micro-ceramic particles, due to their larger size than the infiltration channel width, remain on the upper part of the coating. Subsequently, the liquid low-melting-point alloy solidifies, and surface-metallized wear-resistant particles (II) are embedded in the coating surface, forming an adaptive gradient blade tip wear-resistant sealing composite coating. The resulting adaptive gradient blade tip wear-resistant sealing coating exhibits stronger wear resistance and higher hardness, which is of significant importance for improving the performance and service life of aero-engine blades.

Description

Technical Field

[0001] This invention relates to a vacuum melting and sintering method for an adaptive gradient blade tip wear-resistant sealing coating, belonging to the field of alloy coating technology. Background Technology

[0002] With the development of the aerospace industry, the environment in which aero-engine blades operate is becoming increasingly complex and harsh. Blade tips, subjected to the interaction of thermal and mechanical stresses during high-speed rotation, often experience wear and corrosion, leading to decreased aero-engine performance and even accidents. Applying a high-performance wear-resistant sealing coating to the blade tip surface can provide excellent anti-oxidation, corrosion resistance, and wear resistance, enabling the blades to operate stably for extended periods in harsh environments.

[0003] Currently, vacuum infiltration sintering has become a common technique for preparing blade tip wear-resistant sealing coatings. However, the coating substrate has poor wear resistance, leading to problems such as rapid wear and uneven microstructure. Furthermore, the low-melting-point alloys used in infiltration sintering contain elements such as silicon and boron to lower the melting point. This results in the precipitation of a large number of interconnected silicides in the bonding area between the coating and the base material, as well as in the gaps between high-melting-point powders within the coating. As explained in CN113388756A, the large number of interconnected and growing silicides severely deteriorates the coating's plasticity and high-temperature performance, leading to a decline in the performance of aero-engine blades. Additionally, binders are required during coating preparation to prevent coating collapse, but debinding and sintering cannot completely volatilize the binder, resulting in impurities and numerous pores in the coating, affecting its performance. Adding ceramic particles to the blade tip wear-resistant sealing coating can significantly improve the coating's hardness and wear resistance, while also cutting off the continuously growing hard and brittle silicide phases, thus improving performance. However, the poor wetting properties of ceramics with the coating substrate can affect the infiltration behavior of low-melting-point alloys after melting. Metallization of the ceramic particle surface can solve this problem. To form a gradient composite coating, the current common practice is to mix multiple layers of powder with ceramic particles in different proportions, and then melt-infiltrate and sinter them. This process is complicated, inefficient, and the gradient range is limited and discontinuous. Summary of the Invention

[0004] The purpose of this invention is to address the problems of impurities and numerous pores left in the coating due to the use of binders in traditional vacuum infiltration sintering, which affect the coating's performance; particularly the upward floating problem of low-density ceramic particles in vacuum infiltration sintering. Therefore, this invention proposes a vacuum infiltration sintering method for an adaptive gradient blade tip wear-resistant sealing coating.

[0005] The technical solution implemented by this invention is as follows: a vacuum melting and sintering method for an adaptive gradient blade tip wear-resistant sealing coating, comprising removing the oxide layer on the surface of the single-crystal high-temperature alloy block to be coated, and cleaning to remove oil and impurities; and further comprising the following steps:

[0006] (1) Using a conformal mold, high-melting-point alloy powder (I), surface-metallized wear-resistant ceramic particles (II), and low-melting-point alloy powder (IV) mixed with surface-metallized nano / micro mixed ceramic particles (III) are stacked sequentially from bottom to top on the surface of a single-crystal high-temperature alloy to form the original sample of the adaptive gradient blade tip wear-resistant sealing coating, and then pressed with a pressure block. Among them, the density of the surface-metallized nano / micro mixed ceramic particles is controlled to be greater than the liquid phase density of the low-melting-point alloy powder after surface metallization.

[0007] (2) Place the assembled coating sample into a vacuum melting and sintering furnace, set the process parameters, and evacuate the vacuum until the vacuum degree is less than 3×10. -2 Heating begins after Pa. The low-melting-point alloy powder (IV) melts and carries nano-ceramic particles into the coating through the seepage channels formed by the gaps between the powder particles under the action of gravity, capillary force and fluid viscosity. The content of nano-ceramic particles gradually decreases with increasing depth, while micron-sized ceramic particles remain in the upper part of the coating because their size is larger than the width of the seepage channels. Subsequently, they solidify to form an adaptive gradient blade tip wear-resistant sealing coating (V).

[0008] The high melting point alloy powder (I) has a content of 20~50wt.% in the coating, a particle size of 45~100μm, and is made of MCrAlYX alloy (M is Ni, Co or Ni+Co; X is Ta, Hf or Si), with a melting point of 1500~1700°C.

[0009] The wear-resistant ceramic particles (II) with surface metallization have a particle size of 100~300μm and a content of 2~5wt.% in the coating. Their material is oxide, nitride or carbide.

[0010] The content of the surface-metallized nano / micro mixed ceramic particles (III) in the coating is 20~40 wt.%, wherein the nano ceramic particles have a particle size of 20~100 nm, the micro ceramic particles have a particle size of 10~30 μm, the weight ratio of nano ceramic particles to micro ceramic particles is 1:1~1:3, and the material is a single component or a mixture of oxides, nitrides, and carbides.

[0011] The low-melting-point alloy powder (IV) in the coating has a content of 30~58wt.% and a particle size of 10~45μm. It is a nickel-based alloy with added Si, B or P and a melting point range of 880~1100°C.

[0012] The thickness of the high-melting-point alloy powder (I) and the low-melting-point alloy powder (IV) mixed with surface-metallized nano / micro mixed ceramic particles (III) in the original coating sample is controlled between 0.2 and 0.5 mm; the surface-metallized wear-resistant ceramic particles (II) are embedded in the high-melting-point alloy powder (I) layer, with an exposed ratio of 20 to 80%.

[0013] The nano-ceramic particles, micro-ceramic particles, and wear-resistant ceramic particles are all surface metallized. The surface metallization layer of the ceramic is made of single or mixed components such as W, Cr, and Ni. The layer thickness is controlled between 1 and 15 μm. The standard for selecting the layer thickness is that the overall density of the surface metallized nano / micro ceramic particles (III) is not less than the liquid phase density of the low melting point alloy powder (IV), so as to avoid them from agglomerating and floating during the melting and infiltration sintering process.

[0014] The vacuum melting and infiltration sintering parameters are as follows: heating to 930-1200℃ at a heating rate of 5-10℃ / min, holding at that temperature for 1-2 hours; and then cooling to room temperature at a cooling rate of 10-20℃ / min.

[0015] This invention designs the surface metallization characteristics of nano / micro ceramic particles. Utilizing gravity, capillary force, and fluid viscosity after the low-melting-point alloy melts, the nanoparticles are carried and infiltrated into the coating. The nanoparticle content decreases gradually along the way, while micron-sized ceramic particles, due to their larger size, remain at the top of the coating, thus forming an adaptive gradient blade tip wear-resistant sealing coating. Specifically, for some low-density ceramic particles (such as diamond and alumina), to prevent them from floating upwards after the low-melting-point alloy melts, the surface metallization layer is designed to be thick enough that its overall density is not less than the liquid phase density of the low-melting-point alloy, thereby ensuring that they can be smoothly carried into the coating interior.

[0016] The beneficial effects of this invention are that the vacuum melting and sintering method for an adaptive gradient blade tip wear-resistant sealing coating uses a conformal mold to prepare the coating without the use of a binder, which solves the problem of generating a large number of pores and impurities in the coating, and improves the mechanical properties of the coating.

[0017] This invention employs a method of metallizing the surface of ceramic particles and powder, which can effectively improve the bonding performance between ceramic particles and coatings, while preventing the problem of selected ceramic particles with too low density floating during vacuum melting and sintering.

[0018] The adaptive gradient blade tip wear-resistant sealing coating prepared by this invention features micron-sized ceramic particles with a larger particle size than the gap width of the underlying coating particles during melt infiltration sintering. These particles do not diffuse downwards and remain on the upper part of the coating, increasing its wear resistance. This satisfies the wear resistance requirements of the blade tip wear-resistant coating surface without affecting the compatibility between the coating and the base material. Meanwhile, the nano-sized ceramic particles have a smaller particle size than the gap width of the underlying coating particles. The nano-ceramic powder penetrates into the coating along with the low-melting-point alloy melt, filling the gaps between coating particles, reducing the porosity of the coating particles, and breaking down the precipitated brittle and hard phases that connect the gaps between coating particles, effectively improving the mechanical properties of the coating. The nanoparticle content decreases gradually along the infiltration path, forming a gradient coating with a wide and continuous gradient range. Compared to previous preparation methods, the adaptive gradient blade tip wear-resistant sealing coating prepared by this invention has fewer steps and is more efficient. Attached Figure Description

[0019] Figure 1 A schematic diagram of a method for preparing an adaptive gradient blade tip wear-resistant sealing coating by vacuum melting and sintering;

[0020] Figure 2 A schematic diagram of the completed adaptive gradient blade tip wear-resistant sealing coating;

[0021] Figure 3 A low-magnification optical micrograph of the completed adaptive gradient blade tip wear-resistant sealing coating;

[0022] In the figure, I represents high-melting-point alloys; II represents surface-metallized wear-resistant ceramic particles; III represents surface-metallized micron and nano-ceramic particles; and IV represents low-melting-point alloys. Detailed Implementation

[0023] This embodiment describes a method for preparing an adaptive gradient blade tip wear-resistant sealing coating by vacuum melt infiltration sintering. The specific implementation method is as follows:

[0024] (1) The oxide layer on the surface of the single crystal high-temperature alloy block to be coated is removed by sanding with sandpaper, and the surface of the alloy is removed by ultrasonic cleaning with anhydrous ethanol.

[0025] (2) The wear-resistant ceramic particles (100~300μm), nano ceramic powder (20~100nm), and micron ceramic powder (10~30μm) are surface metallized by coating methods such as chemical plating, electroplating or PVD. The wear-resistant ceramic particles are made of oxides, nitrides or carbides, the micron / nano ceramic powders are made of oxides, nitrides or carbides as a single component or a mixture of components, and the ceramic surface metallization layer is made of W, Cr, Ni or other single components or a mixture of components. The density of the surface metallized ceramic particles is greater than the liquid phase density of the low melting point alloy powder.

[0026] (3) After mixing the surface metallized ceramics together (mass ratio of 1:1 to 1:3), use a ball mill to mix the low melting point alloy powder (nickel-based alloy with added Si, B or P, melting point range of 880 to 1100°C) with the mixed ceramic powder (mass ratio of 3:1 to 4:3) evenly.

[0027] (4) Using a conformal mold, MCrAlYX powder (M is Ni, Co or Ni+Co; X is Ta, Hf or Si, with a particle size of 45~100μm and a content of 20~50 wt.%), surface-metallized wear-resistant ceramic particles (particle size of 100~300μm and a content of 2~5wt.%), and low-melting-point alloy powder mixed with surface-metallized nano / micro mixed ceramic particles are stacked sequentially from bottom to top on the surface of a single-crystal high-temperature alloy. The exposed proportion of surface-metallized wear-resistant ceramic particles is 20~80%, forming the original form of the adaptive gradient blade tip wear-resistant sealing coating.

[0028] (5) Using a vacuum sintering device, the assembled coated sample is placed into the vacuum chamber and the vacuum is evacuated to ≤3×10. -2 Pa is heated to 930-1200℃ at a heating rate of 5-10℃ / min and held for 1-2 hours; then cooled to room temperature at a cooling rate of 10-20℃ / min to complete the vacuum melting and infiltration sintering process.

[0029] The specific implementation is as follows:

[0030] Example 1

[0031] In this embodiment 1, the metal base material is DD26 nickel-based single crystal high-temperature alloy. The oxide layer on the surface of the metal base material is removed by sanding with sandpaper and the oil and impurities are removed by ultrasonic cleaning with anhydrous ethanol. It is then dried for later use.

[0032] In this embodiment, the high melting point alloy powder is NiCoCrAlYTa powder (particle size 45~100μm); the low melting point alloy powder is nickel-based alloy powder with added B (BNi-2 alloy powder, 400 mesh).

[0033] The wear-resistant ceramic particles are selected from Al2O3 wear-resistant particles (90~100 mesh), the micron-sized ceramic powder is made from micron-sized TaC powder (20~30μm), and the nano-sized ceramic powder is made from nano-sized TaC powder (20~100nm). A Ni metal layer is chemically plated on the surface, and the density of the surface-metallized ceramic particles is ≥7.2 / cm³ at room temperature. 3 .

[0034] BNi-2 alloy powder, surface-metallized micron TaC powder, and surface-metallized nano TaC powder were mixed in a mass ratio of 4:1:1 and then ball-milled until homogeneous.

[0035] Using a conformal mold, NiCoCrAlYTa powder, surface-metallized Al2O3 ceramic particles, and low-melting-point alloy powder mixed with surface-metallized nano / micro TaC ceramic particles were stacked sequentially from bottom to top on the surface of a single-crystal high-temperature alloy in a mass ratio of 7:1:12. The coating thickness was 0.5 mm, and the exposed proportion of surface-metallized Al2O3 ceramic particles was 30%, forming the original sample of an adaptive gradient blade tip wear-resistant sealing coating.

[0036] Using a vacuum melting and sintering equipment, the sample is placed in a vacuum furnace, the furnace door is closed, and a vacuum of 3×10⁻⁶ is drawn. -2 After Pa, the process parameters were adjusted and heating was started. The temperature was increased to 1100℃ at a rate of 10℃ / min and held for 2 hours. Then, the temperature was reduced to room temperature at a rate of 15℃ / min to complete the vacuum melting and sintering process of the adaptive gradient blade tip wear-resistant sealing coating.

[0037] Example 2

[0038] In this embodiment 2, the metal base material is DD26 nickel-based single crystal high-temperature alloy. The oxide layer on the surface of the metal base material is removed by sanding with sandpaper and the oil and impurities are removed by ultrasonic cleaning with anhydrous ethanol. It is then dried for later use.

[0039] In this embodiment, the high melting point alloy powder is NiCoCrAlYTa powder (particle size 45~100μm); the low melting point alloy powder is nickel-based alloy powder with added B (BNi-2 alloy powder, 400 mesh).

[0040] The wear-resistant ceramic particles are selected from diamond wear-resistant particles (50~100 mesh), the micron-sized ceramic powder is made of micron-sized Y2O3 powder (10~30μm), and the nano-sized ceramic powder is made of nano-sized Y2O3 powder (20~100nm). A Ni metal layer is chemically plated on the surface, and the density of the surface-metallized ceramic particles is ≥7.2 / cm³ at room temperature. 3 .

[0041] BNi-2 alloy powder, surface-metallized micron Y2O3 powder, and surface-metallized nano Y2O3 powder were mixed in a mass ratio of 5:2:1 and then ball-milled until homogeneous.

[0042] Using a conformal mold, NiCoCrAlYTa powder, surface-metallized diamond wear-resistant particles, and low-melting-point alloy powder mixed with surface-metallized nano / micro Y2O3 ceramic particles were stacked sequentially from bottom to top on the surface of a single-crystal high-temperature alloy in a mass ratio of 7:1:12. The coating thickness was 0.5 mm, and the exposed proportion of surface-metallized diamond wear-resistant particles was 30%, forming the original sample of an adaptive gradient blade tip wear-resistant sealing coating.

[0043] Using a vacuum melting and sintering equipment, the sample is placed in a vacuum furnace, the furnace door is closed, and a vacuum of 3×10⁻⁶ is drawn. -2 After Pa, the process parameters were adjusted and heating was started. The temperature was increased to 1100℃ at a rate of 10℃ / min and held for 2 hours. Then, the temperature was reduced to room temperature at a rate of 15℃ / min to complete the vacuum melting and sintering process of the adaptive gradient blade tip wear-resistant sealing coating.

[0044] Example 3

[0045] In this embodiment 3, the metal base material is DD26 nickel-based single crystal high-temperature alloy. The oxide layer on the surface of the metal base material is removed by sanding with sandpaper and the oil and impurities are removed by ultrasonic cleaning with anhydrous ethanol. It is then dried for later use.

[0046] In this embodiment, the high melting point alloy powder is NiCoCrAlYTa powder (particle size 45~100μm); the low melting point alloy powder is nickel-based alloy powder with added B (BNi-2 alloy powder, 400 mesh).

[0047] The wear-resistant ceramic particles are selected from CBN ceramic particles (80~100 mesh), micron-sized ceramic powder from micron-sized Cr3C2 powder (15~30μm), and nano-sized ceramic powder from nano-sized Cr3C2 powder (20~100nm). A Ni metal layer is chemically plated on the surface, and the density of the surface-metallized ceramic particles is ≥7.2 / cm³ at room temperature. 3 .

[0048] BNi-2 alloy powder, surface-metallized micron Cr3C2 powder, and surface-metallized nano Cr3C2 powder were mixed in a mass ratio of 6:1:1 and then ball-milled until homogeneous.

[0049] Using a conformal mold, NiCoCrAlYTa powder, surface-metallized CBN ceramic particles, and low-melting-point alloy powder mixed with surface-metallized nano / micro Cr3C2 ceramic particles were stacked sequentially from bottom to top on the surface of a single-crystal high-temperature alloy in a mass ratio of 7:1:12. The coating thickness was 0.5 mm, and the exposed proportion of surface-metallized CBN ceramic particles was 30%, forming the original sample of an adaptive gradient blade tip wear-resistant sealing coating.

[0050] Using a vacuum melting and sintering equipment, the sample is placed in a vacuum furnace, the furnace door is closed, and a vacuum of 3×10⁻⁶ is drawn. -2 After Pa, the process parameters were adjusted and heating was started. The temperature was increased to 1100℃ at a rate of 10℃ / min and held for 2 hours. Then, the temperature was reduced to room temperature at a rate of 15℃ / min to complete the vacuum melting and sintering process of the adaptive gradient blade tip wear-resistant sealing coating.

Claims

1. A vacuum melting and sintering method for an adaptive gradient blade tip wear-resistant sealing coating, comprising removing the oxide layer from the surface of the single-crystal high-temperature alloy block to be coated, and cleaning to remove oil and impurities; characterized in that, The method further includes the following steps: (1) Using a conformal mold, high melting point alloy powder, surface-metallized wear-resistant ceramic particles, and low melting point alloy powder mixed with surface-metallized nano / micro mixed ceramic particles are stacked sequentially from bottom to top on the surface of a single crystal high temperature alloy to form the original sample of the adaptive gradient blade tip wear-resistant sealing coating; and the sample is pressed with a pressure block. The surface-metallized nano / micro mixed ceramic particles are controlled to have a density greater than the liquid phase density of the low melting point alloy powder after surface metallization to avoid them from agglomerating and floating during the melting and infiltration sintering process. (2) Place the assembled coating sample into a vacuum melting and sintering furnace; set the vacuum melting and sintering parameters, evacuate the vacuum, and wait until the vacuum degree is less than 3×10 -2 Heating begins after Pa; after reaching a certain temperature, the temperature is held for a period of time, and then cooled to room temperature to obtain the final adaptive gradient blade tip wear-resistant sealing coating; low-melting-point alloy powder melts and carries nano-ceramic particles, which enter the coating through the seepage channels formed by the gaps between the powders under the action of gravity, capillary force and fluid viscosity; and the content of nano-ceramic particles gradually decreases with increasing depth, while micron-sized ceramic particles are retained in the upper part of the coating because their size is larger than the width of the seepage channels, and then solidify to form an adaptive gradient blade tip wear-resistant sealing coating.

2. The vacuum melting and sintering method for an adaptive gradient blade tip wear-resistant sealing coating according to claim 1, characterized in that, The high-melting-point alloy powder has a content of 20-50 wt.% in the coating, a particle size of 45-100 μm, and is made of MCrAlYX alloy, where M is Ni, Co, or Ni+Co, X is Ta, Hf, or Si, and the melting point is 1500-1700°C. The surface-metallized wear-resistant ceramic particles have a particle size of 100-300 μm and a content of 2-5 wt.% in the coating, and are made of oxide, nitride, or carbide. The surface-metallized nano / micron mixed ceramic particles have a content of 20-40 wt.% in the coating, wherein the nano-ceramic particles... The ceramic particles have a particle size of 20-100 nm, the micron-sized ceramic particles have a particle size of 10-30 μm, and the weight ratio of nano-ceramic particles to micron-sized ceramic particles is 1:1 to 1:

3. The material is a single component or a mixture of oxides, nitrides, and carbides. The low-melting-point alloy powder has a content of 30-58 wt.% in the coating, a particle size of 10-45 μm, and is a nickel-based alloy with added Si, B, or P, and a melting point range of 880-1100°C. The surface-metallized nano / micron mixed ceramic particles and the low-melting-point alloy powder are ball-milled to ensure uniform particle dispersion and avoid agglomeration.

3. The vacuum melting and sintering method for an adaptive gradient blade tip wear-resistant sealing coating according to claim 1, characterized in that, The thickness of the high-melting-point alloy powder and the low-melting-point alloy powder mixed with surface-metallized nano / micro mixed ceramic particles in the original coating sample is controlled between 0.2 and 0.5 mm; the surface-metallized wear-resistant ceramic particles are embedded in the high-melting-point alloy powder layer, with the exposed ratio being 20% ​​to 80% of the particle length.

4. The vacuum melting and sintering method for an adaptive gradient blade tip wear-resistant sealing coating according to claim 1, characterized in that, The meaning of the conformal mold is: the inner surface contour of the mold is determined by the outer contour of the single crystal high temperature alloy, so as to ensure that the single crystal high temperature alloy can be installed inside the mold and the gap between the two is no more than 0.1mm.

5. The vacuum melting and sintering method for an adaptive gradient blade tip wear-resistant sealing coating according to claim 1, characterized in that, The vacuum melting and infiltration sintering parameters are as follows: heating to 930-1200℃ at a heating rate of 5-10℃ / min, holding at that temperature for 1-2 hours; and then cooling to room temperature at a cooling rate of 10-20℃ / min.

6. The vacuum melting and sintering method for an adaptive gradient blade tip wear-resistant sealing coating according to claim 2, characterized in that, The nano-ceramic particles, micro-ceramic particles, and wear-resistant ceramic particles are all surface metallized. The surface metallization layer is made of a single or mixed composition of W, Cr, and Ni, with a layer thickness controlled between 1 and 15 μm. The standard for selecting the layer thickness is that the overall density of the surface metallized nano / micro-ceramic particles is not less than the liquid phase density of the low-melting-point alloy powder, so as to avoid them from agglomerating and floating during the melting and infiltration sintering process.

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