A method for in-situ generation of Y3Al5O 12 Method for thermal barrier coating and Y3Al5O 12 Thermal barrier coating

Abstract

The application belongs to the technical field of thermal barrier coating preparation and modification, and particularly discloses a method for in-situ generation of Y3Al5O 12 Method for preparing thermal barrier coating and Y3Al5O 12 The application discloses a method for in-situ generation of Y3Al5O 12 The application discloses a method for in-situ generation of Y3Al5O The application discloses a method for in-situ generation of Y3Al5O

Description

Technical Field

[0001] This invention belongs to the field of thermal barrier coating preparation and modification technology, specifically relating to an in-situ generation method for Y3Al5O on the surface of titanium alloys. 12 Methods of thermal barrier coatings and Y3Al5O 12 Thermal barrier coating. Background Technology

[0002] A gas turbine is an internal combustion engine that uses continuously flowing, high-temperature gas as its working medium to drive a high-speed rotating impeller, converting the chemical energy of fuel into kinetic energy. It is a type of rotating impeller-type thermal engine. Increasing the inlet temperature of a gas turbine turbine (i.e., the temperature of the gas before it enters the turbine) can not only improve the thermal efficiency of aero engines but also reduce harmful gas emissions while saving fuel. The hot-end components of a gas turbine are composed of nickel-based superalloys or titanium alloys. Despite nearly forty years of effort, simply increasing the upper temperature limit of alloys is no longer sufficient to meet the demands of high-performance engines. The application of thermal barrier coatings (TBCs) technology is a key technology for solving the problem of increasing the turbine inlet temperature.

[0003] Thermal barrier coatings (TBCs) are functional coatings that provide thermal insulation and are primarily applied to the surfaces of high-temperature hot-end components in gas turbines to protect the alloy substrate. TBCs effectively isolate high-temperature combustion gas from the high-temperature hot-end component substrate, protecting the high-temperature alloy of the substrate. This results in a decrease in the alloy surface temperature while increasing the combustion gas temperature, leading to a significant improvement in gas turbine efficiency. A ceramic layer is a prerequisite for ensuring the effective thermal insulation of the TBC.

[0004] Currently, the preparation of thermal barrier coatings for aero-engines relies on large-scale coating preparation systems, such as plasma spraying, plasma physical vapor deposition, and plasma-assisted physical vapor deposition. These systems are expensive and cannot be used in field operations where construction conditions are not available. Summary of the Invention

[0005] The purpose of this invention is to provide a method for in-situ generation of Y3Al5O on the surface of titanium alloys. 12 Methods of thermal barrier coatings and Y3Al5O 12 Thermal barrier coatings are developed to address the problems that the preparation of thermal barrier coatings for aero-engines relies on large-scale coating preparation systems, which are expensive and cannot be achieved in field operations where construction conditions are not available.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] In a first aspect, the present invention provides an in-situ generation method for Y3Al5O on the surface of a titanium alloy. 12 Methods for applying thermal barrier coatings include:

[0008] Pretreatment of the titanium alloy substrate surface;

[0009] Si powder, NaF, Al2O3 and Y2O3 were uniformly mixed and ball-milled to obtain a ball-milled mixed powder;

[0010] The pretreated titanium alloy matrix was embedded in the ball-milled mixed powder and heated under a set temperature to generate Y3A in situ on the surface of the titanium alloy matrix. 15 O 12 Thermal barrier coating.

[0011] Furthermore, the pretreatment of the titanium alloy substrate surface specifically includes:

[0012] Polish the surface of the titanium alloy substrate;

[0013] The polished titanium alloy substrate is cleaned and dried.

[0014] Furthermore, the polishing process involves sequentially polishing the surface of the titanium alloy substrate using 240#, 400#, 600#, 800#, and 1200# sandpaper.

[0015] Furthermore, the polished titanium alloy substrate is ultrasonically cleaned in acetone, alcohol, and deionized water in sequence for 10 to 20 minutes each.

[0016] Furthermore, the titanium alloy matrix is ​​TC4 titanium alloy.

[0017] Furthermore, the ball milling is performed using a planetary ball mill; the ball-to-material ratio during ball milling is 12:1, the rotation speed is 300 r / min, and the ball milling time is 4 h to 8 h.

[0018] Furthermore, the mixed powder contains 15 wt.% Si powder, 6 wt.% NaF powder, 2 wt.%~10 wt.% Y2O3 powder, and 69 wt.%~77 wt.% Al2O3 powder.

[0019] Furthermore, the step of embedding the pretreated titanium alloy matrix into the ball-milled mixed powder and heating it under a set temperature condition specifically involves:

[0020] The TC4 titanium alloy matrix was embedded in an alumina crucible containing a mixture of ball-milled Al2O3, Y2O3, NaF and Si powders. After being sealed with a high-temperature binder, it was placed in a tube furnace and heated to the holding temperature while nitrogen was introduced as a protective gas. After the holding time was reached, it was removed and air-cooled.

[0021] Furthermore, the heating rate inside the tube furnace is 5℃ / min to 10℃ / min, the holding temperature is 1000℃ to 1100℃, and the holding time is 1 h to 4 h.

[0022] Secondly, the present invention provides a Y3Al5O 12 Thermal barrier coating, the Y3Al5O 12 Thermal barrier coating is formed in situ on the surface of a titanium alloy according to any one of the above-mentioned methods to generate Y3Al5O 12 The thermal barrier coating was prepared by a method.

[0023] The present invention has at least the following beneficial effects:

[0024] 1. This invention pretreats the surface of a titanium alloy substrate; uniformly mixes Si powder, NaF, Al2O3, and Y2O3 and ball-mills them to obtain a ball-milled mixed powder; embeds the pretreated titanium alloy substrate into the ball-milled mixed powder and heats it under a set temperature to generate a YAG thermal barrier coating in situ on the surface of the titanium alloy substrate; it provides a method for growing a YAG thermal barrier coating on the surface of a titanium alloy using an embedding method through in-situ growth; it is low-cost, the prepared YAG thermal barrier coating is generated by atomic diffusion, the YAG thermal barrier coating has an inherent bonding advantage with the titanium alloy substrate, and it does not rely on large-scale equipment.

[0025] 2. The method provided by this invention can provide technical support for high-temperature protection of titanium alloys. The YAG generated by the reaction of Al2O3 and Y2O3 under certain conditions has good thermal stability, low thermal conductivity, and low oxygen diffusion rate. Furthermore, it achieves effective bonding between YAG and a Ti-Si coating, forming a dense YAG coating. The preparation of this coating is not limited by the shape of the workpiece and can effectively protect titanium alloys in high-temperature service environments. Attached Figure Description

[0026] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0027] Figure 1 Schematic diagram of in-situ formation of YAG thermal barrier coating on titanium alloy surface;

[0028] Figure 2 XRD pattern of YAG thermal barrier coating;

[0029] Figure 3The TGO microstructures after isothermal oxidation at 1100℃ for 1h (b), 5h (c), 10h (d), 15h (e), 50h (f), 100h (g), 200h (h) and 300h (i) are: the traditional 8YSZ single ceramic thermal barrier coating spray state (a);

[0030] Figure 4 The microstructures of TGO after isothermal oxidation at 1100℃ for 1h (b), 5h (c), 10h (d), 25h (e), 50h (f), 100h (g), 200h (h) and 300h (i) are shown in the sprayed state (a).

[0031] Figure 5 The microstructure of the cross-section of 8YSZ single ceramic TBCs after corrosion at 1250℃ for 1 h ((a), (b) and (c)), 4 h ((d), (e) and (f)) and 12 h ((g), (h) and (i));

[0032] Figure 6 The microstructures of YAG-containing ceramic TBCs after corrosion at 1250℃ for 1 h ((a), (b) and (c)), 4 h ((d), (e) and (f)) and 12 h ((g), (h) and (i)) are shown. Detailed Implementation

[0033] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0034] The following detailed description is exemplary and intended to provide further detailed explanation of the invention. Unless otherwise specified, all technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this invention is for describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention.

[0035] Yttrium aluminum garnet (Y3Al5O) 12 YAG (Gatanium ore) is a promising potential material for thermal barrier coatings. It has a garnet structure and its thermal properties range from room temperature to its melting point (1970). o C) Both exhibit good thermal stability and low thermal conductivity. The oxygen diffusion rate within YAG is 10 orders of magnitude lower than that in conventional ZrO2, thus YAG effectively protects the substrate and the metal binder layer. Furthermore, the thermal conductivity of YAG decreases with decreasing temperature, and it also possesses excellent properties such as high hardness, lower density, and low reactivity with CMAS.

[0036] like Figure 1 As shown, Y3Al5O is generated in situ on the surface of a titanium alloy.12 Methods for applying thermal barrier coatings include:

[0037] S1: Using TC4 titanium alloy as the substrate, the surface of the titanium alloy substrate was polished with sandpaper of different grits before preparation; the polished titanium alloy substrate was ultrasonically cleaned in acetone, alcohol and deionized water in sequence, and then dried for use to obtain the pretreated TC4 titanium alloy substrate.

[0038] The purpose of polishing is to remove the oxide film on the surface of TC4 titanium alloy;

[0039] The surface of the TC4 titanium alloy substrate was polished sequentially with 240#, 400#, 600#, 800#, and 1200# sandpaper, and ultrasonically cleaned in acetone, alcohol, and deionized water for 10 to 20 minutes each.

[0040] S2: Coating preparation using solid powder embedding method: Si powder, NaF, Al2O3 and Y2O3 are uniformly mixed and ball-milled using a planetary ball mill to make the powder uniformly mixed and fully refined, and to obtain the ball-milled mixed powder.

[0041] S3: A YAG thermal barrier coating is generated in situ on the surface of a pretreated TC4 titanium alloy substrate using ball-milled mixed powder under a set temperature condition.

[0042] Specifically, the TC4 titanium alloy matrix is ​​embedded in an alumina crucible containing a mixture of ball-milled Al2O3, Y2O3, NaF and Si powders. After being sealed with a high-temperature binder, it is placed in a tube furnace and heated to the holding temperature while nitrogen is introduced as a protective gas. After the holding time is reached, it is removed and air-cooled.

[0043] At high temperatures, a series of chemical reactions cause the formation of a Ti-Si coating and YAG on the surface of TC4 titanium alloy. On the one hand, Al2O3 and Y2O3 react at high temperatures to generate YAG. On the other hand, under the activation of NaF, the Ti-Si coating generated by the interdiffusion of Si and the titanium alloy substrate effectively combines with YAG during the growth process, thereby forming a dense YAG thermal barrier coating on the surface of the TC4 titanium alloy substrate.

[0044] YAG possesses characteristics such as thermal stability, low thermal conductivity, and low oxygen diffusion rate, making it an ideal material for thermal barrier coatings. Furthermore, an effective combination of YAG and Ti-Si coatings was achieved, forming a dense YAG coating. The preparation of this coating is not limited by the shape of the workpiece and can effectively protect titanium alloys in high-temperature service environments.

[0045] The mixed powder contains 15 wt.% Si, 6 wt.% NaF, 2 wt.%–10 wt.% Y₂O₃, and 69 wt.%–77 wt.% Al₂O₃.

[0046] The ball-to-material ratio during ball milling was 12:1, the rotation speed was 300 r / min, and the milling time was 4 h to 8 h.

[0047] The heating rate inside the tube furnace is 5℃ / min ~ 10℃ / min, the holding temperature is 1000℃ ~ 1100℃, and the holding time is 1 h ~ 4 h.

[0048] Example 1

[0049] The surface of the titanium alloy substrate was polished sequentially using 240#, 400#, 600#, 800#, and 1200# sandpaper; the polished titanium alloy substrate was then ultrasonically cleaned for 10 minutes in acetone, alcohol, and deionized water, respectively.

[0050] 15 wt.% Si powder, 6 wt.% NaF, 69 wt.% Al2O3 and 10 wt.% Y2O3 were uniformly mixed and ball-milled to obtain a ball-milled mixed powder;

[0051] The pretreated titanium alloy substrate was embedded in the ball-milled mixed powder, heated to 1000℃ and held at a temperature of 5℃ / min under set temperature conditions. After holding for 1 hour, it was taken out and air-cooled, and a YAG thermal barrier coating was generated in situ on the surface of the titanium alloy substrate.

[0052] Example 2

[0053] The surface of the titanium alloy substrate was polished sequentially using 240#, 400#, 600#, 800#, and 1200# sandpaper; the polished titanium alloy substrate was then ultrasonically cleaned for 15 minutes in acetone, alcohol, and deionized water, respectively.

[0054] 15 wt.% Si powder, 6 wt.% NaF, 74 wt.% Al2O3 and 5 wt.% Y2O3 were uniformly mixed and ball-milled to obtain a ball-milled mixed powder;

[0055] The pretreated titanium alloy substrate was embedded in the ball-milled mixed powder and heated to 1050℃ at a heating rate of 8℃ / min under set temperature conditions. After holding at this temperature for 2 hours, it was removed and air-cooled, thus generating a YAG thermal barrier coating in situ on the surface of the titanium alloy substrate.

[0056] Example 3

[0057] The surface of the titanium alloy substrate was polished sequentially using 240#, 400#, 600#, 800#, and 1200# sandpaper; the polished titanium alloy substrate was then ultrasonically cleaned for 15 minutes in acetone, alcohol, and deionized water, respectively.

[0058] 15 wt.% Si powder, 6 wt.% NaF, 75 wt.% Al2O3 and 4 wt.% Y2O3 were uniformly mixed and ball-milled to obtain a ball-milled mixed powder;

[0059] The pretreated titanium alloy substrate was embedded in the ball-milled mixed powder and heated to 1080℃ at a heating rate of 7℃ / min under set temperature conditions. After holding at this temperature for 3 hours, it was removed and air-cooled, thus generating a YAG thermal barrier coating in situ on the surface of the titanium alloy substrate.

[0060] Example 4

[0061] The surface of the titanium alloy substrate was polished sequentially using 240#, 400#, 600#, 800#, and 1200# sandpaper; the polished titanium alloy substrate was then ultrasonically cleaned for 15 minutes in acetone, alcohol, and deionized water, respectively.

[0062] 15 wt.% Si powder, 6 wt.% NaF, 77 wt.% Al2O3 and 2 wt.% Y2O3 were uniformly mixed and ball-milled to obtain a ball-milled mixed powder;

[0063] The pretreated titanium alloy substrate was embedded in the ball-milled mixed powder and heated to 1100℃ at a heating rate of 10℃ / min under set temperature conditions. After holding at this temperature for 4 hours, it was taken out and air-cooled, and a YAG thermal barrier coating was generated in situ on the surface of the titanium alloy substrate.

[0064] like Figures 2-4 As shown, thermally grown oxide (TGO).

[0065] High-temperature oxidation experiments of different durations show that, since yttrium-stabilized zirconia (8YSZ) is an oxygen-permeable material, oxygen in the air can easily pass through the ceramic layer to reach the surface of the adhesive layer during high-temperature oxidation, causing the adhesive layer to oxidize rapidly. However, for TBCs containing YAG ceramics, the good oxygen barrier properties of YAG make it difficult for oxygen to pass through the ceramic layer to reach the surface of the adhesive layer, thus slowing down the rapid oxidation of the adhesive layer of the coating system and improving the high-temperature oxidation resistance of the double ceramic layer system.

[0066] like Figure 5As shown, after different corrosion times at 1250 °C in a traditional 8YSZ single-ceramic TBCs system, CMAS (CaO-MgO-Al2O3-SiO2) reacted violently with 8YSZ, leading to the leaching of Y ions and initiating a transformation of the tetragonal phase to the monoclinic phase in 8YSZ. After 12 hours, CMAS completely penetrated the 8YSZ ceramic layer. This indicates that 8YSZ is insufficient to withstand the penetration and damage of CMAS, ultimately leading to coating failure. Figure 6 It can be seen that after corrosion at 1250℃ for different times, CMAS did not penetrate the YAG ceramic surface layer of the YAG ceramic system, protecting the underlying ceramic layer 8YSZ from corrosion and damage. At the same time, the internal structure of the YAG ceramic layer remained intact, with only a small amount of needle-like and blocky high-melting-point inert apatite material generated at the CMAS / YAG interface. This indicates that YAG itself has the characteristic of blocking CMAS penetration, and its sealing in the pores and cracks of the coating will further prevent CMAS penetration, thus improving the coating system's resistance to CMAS corrosion.

[0067] As is known from common technical knowledge, this invention can be implemented through other embodiments that do not depart from its spirit or essential characteristics. Therefore, the disclosed embodiments described above are merely illustrative in all respects and are not the only ones. All modifications within the scope of this invention or its equivalents are included in this invention.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. An in-situ formation of Y3Al5O on the surface of a titanium alloy 12 The method for applying a thermal barrier coating is characterized by, include: Pretreatment of the titanium alloy substrate surface; Si powder, NaF, Al2O3 and Y2O3 were uniformly mixed and ball-milled to obtain a ball-milled mixed powder; The pretreated titanium alloy matrix was embedded in the ball-milled mixed powder and heated under a set temperature to generate Y3Al5O in situ on the surface of the titanium alloy matrix. 12 Thermal barrier coating; The mixed powder contains 15 wt.% Si, 6 wt.% NaF, 2 wt.%~10 wt.% Y2O3, and 69 wt.%~77 wt.% Al2O3. The step of embedding the pretreated titanium alloy matrix into the ball-milled mixed powder and heating it under a set temperature condition specifically involves: The TC4 titanium alloy matrix was embedded in an alumina crucible containing a mixture of ball-milled Al2O3, Y2O3, NaF and Si powders. After being sealed with a high-temperature binder, it was placed in a tube furnace and heated to the holding temperature while nitrogen was introduced as a protective gas. After the holding time was reached, it was removed and air-cooled. The heating rate inside the tubular furnace is 5℃ / min ~ 10℃ / min, the holding temperature is 1000℃ ~ 1100℃, and the holding time is 1 h ~ 4 h.

2. The method for in-situ generation of Y3Al5O on the surface of a titanium alloy according to claim 1 12 The method for applying a thermal barrier coating is characterized by, The pretreatment of the titanium alloy substrate surface specifically includes: Polish the surface of the titanium alloy substrate; The polished titanium alloy substrate is cleaned and dried.

3. The method for in-situ generation of Y3Al5O on the surface of a titanium alloy according to claim 2 12 The method for applying a thermal barrier coating is characterized by, The polishing process involves sequentially polishing the surface of the titanium alloy substrate with 240#, 400#, 600#, 800#, and 1200# sandpaper.

4. The method for in-situ generation of Y3Al5O on the surface of a titanium alloy according to claim 2 12 The method for applying a thermal barrier coating is characterized by, The polished titanium alloy substrate was ultrasonically cleaned in acetone, alcohol, and deionized water for 10 to 20 minutes each.

5. The method for in-situ generation of Y3Al5O on the surface of a titanium alloy according to claim 1 12 The method for applying a thermal barrier coating is characterized by, The titanium alloy matrix is ​​TC4 titanium alloy.

6. The method for in-situ generation of Y3Al5O on the surface of a titanium alloy according to claim 1 12 The method for applying a thermal barrier coating is characterized by, The ball milling was carried out using a planetary ball mill; the ball-to-material ratio was 12:1, the rotation speed was 300 r / min, and the milling time was 4 h to 8 h.

7. A Y3Al5O 12 Thermal barrier coating, characterized in that, The Y3Al5O 12 Thermal barrier coating for in-situ generation of Y3Al5O on the surface of a titanium alloy according to any one of claims 1-6 12 The thermal barrier coating was prepared by a method.

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