A method for laser preparation of titanium alloy multi-element ceramic modified high-temperature oxidation resistant layer

Abstract

The present invention provides a method for laser-preparing a multi-element ceramic-modified high-temperature oxidation-resistant layer on a titanium alloy. The main process is: applying a pre-coating on the surface of a substrate, and then forming a high-temperature oxidation-resistant layer on the surface of the pre-coating by laser melting deposition. The pre-coating is composed of Ni625 and SiC in a mass ratio of 92:8; the high-temperature oxidation-resistant layer is composed of Ni625, Ni-coated WC, and SiC in a mass ratio of 86:6:8; the Ni-coated WC comprises 15wt%. In the present invention, Ni625 (Ni-coated WC) and SiC are deposited on the surface of the pre-coating by laser melting deposition to form a high-temperature oxidation-resistant layer, resulting in a TA1 titanium alloy with excellent surface morphology and strong high-temperature oxidation resistance. This method has the characteristics of simple and convenient process, strong practicality, and easy promotion and application.

Description

Technical Field

[0001] The invention relates to the technical field of material surface strengthening, and in particular to a method for laser-preparing a titanium alloy multi-element ceramic modified high-temperature oxidation-resistant layer. Background Art

[0002] Laser cladding is an advanced surface modification technology that can deposit a high-performance coating onto a substrate to enhance its performance. Laser cladding involves irradiating the coating material and the substrate surface with a laser, causing the coating and a small amount of substrate to melt and then rapidly solidify. This creates a coating with a distinct metallurgical bond, thereby improving the substrate's surface properties, including wear resistance, corrosion resistance, and oxidation resistance.

[0003] Titanium alloys, a key material in the aerospace industry, experience elevated surface temperatures when subjected to friction, leading to rapid oxidation and spalling, which reduces their service life. Currently, surface modification techniques are crucial for imparting specialized surface properties to titanium alloys without altering their overall performance. Common surface modification methods include ion implantation, plasma spraying, vapor deposition, and laser cladding. Coatings produced by plasma spraying exhibit high porosity, typical thermal spray defects, and uneven microstructure. Coatings produced by vapor deposition exhibit weak adhesion to the workpiece and poor uniformity. Compared to other surface modification techniques, coatings produced by laser cladding achieve a metallurgical bond with the substrate, preventing flaking or cracking and exhibiting extremely low porosity. Coating thickness can be precisely controlled, with high repeatability. Currently, laser cladding technology holds great potential for developing high-temperature oxidation-resistant coatings and is widely used in a wide range of industrial applications. Titanium alloys are structural metals with advantages such as high lightness, excellent corrosion resistance, and excellent heat resistance, making them widely used in aerospace engine manufacturing. The use of laser cladding technology to prepare high-temperature anti-oxidation coatings on the surface of titanium alloys can effectively solve the problem of poor performance of titanium alloys at high temperatures, improve the surface performance and service life of titanium alloys in key areas, and is of great significance to expanding the application range of titanium alloys and the development of the aerospace field. Summary of the Invention

[0004] In response to the above-mentioned shortcomings of the prior art, the present invention provides a method for laser-preparing a multi-element ceramic-modified high-temperature oxidation-resistant layer on a titanium alloy. In this method, a pre-coating is applied to the surface of a substrate, and then a high-temperature oxidation-resistant layer is formed on the surface of the pre-coating by laser melting deposition. In the present invention, Ni625-(Ni encased in WC)-SiC is deposited on the surface of the pre-coating by laser melting deposition to form a high-temperature oxidation-resistant layer, thereby obtaining a TA1 titanium alloy with excellent surface morphology and strong resistance to high-temperature oxidation. This method has the characteristics of simple and convenient process, strong practicality, and easy promotion and application.

[0005] The technical solutions of the present invention are as follows:

[0006] A method for laser-preparing a multi-element ceramic modified high-temperature oxidation-resistant layer of titanium alloy, the main process of which is as follows:

[0007] A pre-coating is applied to the surface of the substrate, and then a high-temperature oxidation resistant layer is formed on the surface of the pre-coating by laser melting and deposition;

[0008] The pre-coating is composed of raw materials of Ni625 and SiC with a mass ratio of 92:8;

[0009] The high-temperature oxidation resistant layer is composed of raw materials of Ni625, Ni-coated WC and SiC in a mass ratio of 86:6:8; in the Ni-coated WC, Ni accounts for 15wt%.

[0010] Preferably, the purity of the raw materials in the pre-coating layer and the high-temperature oxidation resistant layer is greater than 99.5%; the size of Ni625 powder is 50-200 μm, the size of SiC powder is 40-100 μm, and the size of Ni-coated WC powder is 20-80 μm.

[0011] Preferably, the above-mentioned method for laser preparation of titanium alloy multi-element ceramic modified high temperature oxidation resistant layer comprises the following steps:

[0012] (1) Weighing and mixing the raw materials for the pre-coating, then adding a binder and mixing to obtain a paste-like mixture;

[0013] (2) Using a pre-coating method, a coating with a thickness of 0.8 mm is formed on the surface of the titanium alloy substrate, and the coating is allowed to dry naturally as a pre-coating;

[0014] (3) The raw materials constituting the high-temperature oxidation resistant layer are fully mixed to obtain a powder mixture; the powder mixture is blown onto the surface of the pre-coating by laser coaxial powder feeding technology, and the high-temperature oxidation resistant layer is formed by laser melting deposition. The process parameters are: laser power 1300W, scanning speed 15mm / s, protective argon gas flow rate 30L / min, multi-pass overlap rate 30%, and powder feeding speed 12g / min.

[0015] Preferably, in step (1), the raw materials for the pre-coating are weighed and dried, and then fully mixed by a mechanical powder mixer before use.

[0016] Preferably, the drying time for each raw material of the pre-coating is 2 hours.

[0017] Preferably, in step (1), the binder is a mixture of water glass and water, the volume ratio of water glass to water is 1:3, and the molecular formula is Na2O·nSiO2.

[0018] Preferably, in step (2), the titanium alloy substrate is a TA1 substrate.

[0019] Preferably, in step (3), the raw materials constituting the high-temperature oxidation resistant layer are dried and mechanically mixed to achieve the purpose of sufficient mixing.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. Ni625-(Ni-coated WC)-SiC (Ni-coated WC powder accounts for 15wt%) is deposited on the surface of the pre-coating by laser melting deposition to form an upper high-temperature oxidation-resistant layer. The overall cladding layer can improve the high-temperature oxidation resistance of the TA1 titanium alloy surface.

[0022] 2. The method of the present invention has the characteristics of simple and convenient process, strong practicality, and easy promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0024] Figure 1 (a, b) are the bonding areas between the TA1 substrate and the cladding layer.

[0025] Figure 2 It is the middle part of the cladding layer.

[0026] Figure 3 This is a test diagram of the high-temperature oxidation performance of TA1 substrate and cladding layer. DETAILED DESCRIPTION

[0027] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0028] Example 1

[0029] A method for laser-preparing a titanium alloy multi-element ceramic modified high-temperature oxidation-resistant layer, comprising the following steps:

[0030] (1) Using wire cutting technology, cut TA1 titanium alloy into cubes with a length of 10 mm, a width of 10 mm, and a thickness of 10 mm. Use No. 160 sandpaper to polish the surface of the TA1 titanium alloy to remove the oxide layer on the surface of the TA1 substrate. Then use anhydrous ethanol and acetone to clean the surface of the TA1 substrate to remove debris and stains. Use a hair dryer to quickly dry it to obtain a test block for standby use.

[0031] (2) 10 g of pre-coated powder was dried at 150 °C for 2 h, mixed thoroughly with a ball mill, added with a binder, and stirred with a glass rod to obtain a paste-like mixture;

[0032] Pre-coated, consisting of Ni625 and SiC in a mass ratio of 92:8;

[0033] Ni625 powder is composed of the following components in weight percentage: C 0.10%, Cr 21.5%, Si 0.50%, Mo 9.0%, Fe 5.0%, Al 0.4%, Ti 0.4%, Cu 0.5%, Mn 0.5%, Nb 4.0%, and the balance is Ni;

[0034] The binder is a mixture of water glass and water, with a volume ratio of water glass to water of 1:3 and a molecular formula of Na2O·nSiO2;

[0035] (3) Using the pre-coating method, a 0.8 mm thick coating was formed on the surface of the TA1 substrate test block. The pre-coated sample was placed in a cool place for 48 hours and allowed to dry naturally to form a pre-coating on the sample surface.

[0036] (4) Dry 10 g of high-temperature oxidation layer raw material powder for 2 h, feed the powder and mix thoroughly to obtain a powder mixture;

[0037] The high-temperature oxidation resistant layer is composed of Ni625, Ni-wrapped WC, and SiC in a mass ratio of 86:6:8; in the Ni-wrapped WC, Ni accounts for 15wt%;

[0038] (5) The powder mixture is blown onto the surface of the pre-coating by laser coaxial powder feeding technology. After laser melting and deposition, a high-temperature oxidation-resistant gradient coating is formed on the surface of the pre-coating. The process parameters are: laser power 1300W, scanning speed 15mm / s, protective argon gas flow rate 30L / min, multi-pass overlap rate 30%, and powder feeding speed 12g / min;

[0039] The purity of the raw materials in the pre-coating and high-temperature oxidation resistant layer is greater than 99.5%; the Ni625 powder size is 50-200μm, the SiC powder size is 40-100μm, and the Ni-coated WC powder size is 20-80μm;

[0040] The substrate TA1 is composed of the following components in weight percentage: Fe 0.2%, C 0.08%, N 0.03%, O 0.18%, H 0.015%, and the balance Ti.

[0041] The cladding layer refers to the overall coating formed by melting the prefabricated coating and the high-temperature oxidation-resistant layer through the high temperature of the laser beam.

[0042] The present invention selects a TA1 titanium alloy substrate for laser cladding treatment, pre-placing a mixed powder of Ni625 and SiC in a mass ratio of 92:8 on the surface of the TA1 titanium alloy substrate to form a pre-coating; then using laser coaxial powder feeding technology to deposit a mixed powder of Ni625, Ni-coated WC and SiC in a mass ratio of 86:6:8 on the surface of the pre-coating to obtain a TA1 material with a high-temperature oxidation resistant coating. The metallographic photograph of the material is shown in FIG. Figure 1 .

[0043] Figure 1 In a, the left side is the TA1 substrate and the right side is the pre-coated layer; Figure 1 As shown in a, there is an obvious metallurgical bond between the pre-coating and the TA1 substrate, without any obvious cracks or pores. Figure 1 b shows that the overall bonding between the pre-coating and the substrate is good, and the overall distribution of the organizational structure is relatively uniform and dense;

[0044] Figure 2 This is the microstructure diagram of the middle part of the cladding layer. It can be seen that a large number of grains are generated in this area. During the rapid laser cooling process, the grains do not have time to grow, resulting in small grains here. The cladding layer is uniform, tight, and well-bonded, with blocky precipitates dispersed.

[0045] Figure 3 It shows that the high-temperature oxidation resistance of the TA1 material surface is significantly improved after laser surface treatment. The high-temperature oxidation resistance of the TA1 substrate surface is significantly enhanced after laser surface treatment compared with that before treatment, which is mainly attributed to the formation of a dense high-temperature oxidation-resistant coating during the rapid cooling process of the laser.

[0046] Comprehensive analysis shows that laser cladding can greatly improve the high-temperature oxidation resistance of TA1 titanium alloy and form an anti-oxidation coating, thereby achieving the purpose of improving the high-temperature oxidation resistance of the TA1 titanium alloy surface.

[0047] Although the present invention has been described in detail with reference to preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, a person of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and such modifications or substitutions shall be within the scope of the present invention. Any person skilled in the art who can easily conceive of changes or substitutions within the technical scope disclosed in the present invention shall be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.

Claims

1. A method for laser preparation of a titanium alloy multi-element ceramic modified high temperature oxidation resistant layer, characterized in that: The main process is: A pre-coating is applied to the surface of the substrate, and then a high-temperature oxidation resistant layer is formed on the surface of the pre-coating by laser melting and deposition; The pre-coating is composed of raw materials of Ni 625 and SiC with a mass ratio of 92:8; The high-temperature oxidation layer is composed of Ni 625, Ni-coated WC, and SiC in a mass ratio of 86:6:8; in the Ni-coated WC, Ni accounts for 15wt%; The method for laser-preparing a multi-element ceramic modified high-temperature oxidation-resistant layer of titanium alloy comprises the following steps: (1) Weighing and mixing the raw materials for the pre-coating, then adding a binder and mixing to obtain a paste-like mixture; (2) Using a pre-coating method, a coating with a thickness of 0.8 mm is formed on the surface of the titanium alloy substrate, and the coating is allowed to dry naturally as a pre-coating; (3) The raw materials constituting the high-temperature oxidation resistant layer are fully mixed to obtain a powder mixture; the powder mixture is blown onto the surface of the pre-coating by laser coaxial powder feeding technology, and the high-temperature oxidation resistant layer is formed by laser melting deposition. The process parameters are: laser power 1300W, scanning speed 15mm / s, protective argon gas flow rate 30L / min, multi-pass overlap rate 30%, and powder feeding speed 12g / min.

2. The method for laser preparation of titanium alloy multi-element ceramic modified high temperature oxidation resistant layer according to claim 1, characterized in that: The purity of the raw materials in the pre-coating layer and the high-temperature oxidation resistant layer is greater than 99.5%; the size of Ni 625 powder is 50-200 μm, the size of SiC powder is 40-100 μm, and the size of Ni-coated WC powder is 20-80 μm.

3. The method for laser preparation of titanium alloy multi-element ceramic modified high temperature oxidation resistant layer according to claim 1, characterized in that: In step (1), the raw materials for the pre-coating are weighed and dried, and then fully mixed by a mechanical mixer before use.

4. The method for laser preparation of titanium alloy multi-element ceramic modified high temperature oxidation resistant layer according to claim 3, characterized in that: The drying time for each raw material of the pre-coating is 2 hours.

5. The method for laser preparation of titanium alloy multi-element ceramic modified high temperature oxidation resistant layer according to claim 1, characterized in that: In step (1), the binder is a mixture of water glass and water, the volume ratio of water glass to water is 1:3, and the molecular formula is Na2O·nSiO2.

6. The method for laser preparation of titanium alloy multi-element ceramic modified high temperature oxidation resistant layer according to claim 1, characterized in that: In step (2), the titanium alloy substrate is a TA1 substrate.

7. The method for laser preparation of titanium alloy multi-element ceramic modified high temperature oxidation resistant layer according to claim 1, characterized in that: In step (3), the raw materials constituting the high temperature oxidation resistant layer are dried and mechanically mixed.

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