A method for laser preparation of multi-element refined wear-resistant laminated layers of TC17 titanium alloy

Abstract

The present invention provides a method for preparing a multi-element refined wear-resistant laminate of TC17 titanium alloy by laser. In the method, a bottom coating and a top coating are sequentially obtained on the surface of TC17 by LMD treatment, and the top coating is located on the bottom coating; the bottom coating is obtained by depositing Stellite31PM powder and then subjecting it to LMD treatment; the top coating is obtained by using Stellite31PM, Si 3 N 4 , Mo, and Zr are mixed in a certain proportion and processed by LMD to obtain the coating. The method provided by the present invention can obtain a multi-phase coating, and the wear resistance is significantly enhanced. The invention has the advantages of simple operation, obvious enhancement effect, universal process, and easy promotion and use.

Description

Technical Field

[0001] The invention relates to the technical field of material surface strengthening, and in particular to a method for preparing a multi-element refined wear-resistant laminate of TC17 titanium alloy by laser. Background Art

[0002] Laser melting deposition (LMD) is a laser additive manufacturing technology that uses a laser heat source to heat the powder and then cool it rapidly, and directly prepares parts through multi-layer deposition. It has the advantages of high molding efficiency and high processing precision. By depositing powders of different compositions, the wear resistance, corrosion resistance, heat resistance and oxidation resistance of the material surface can be improved, and it has a wide range of applications.

[0003] Stellite cobalt-based alloys can be used in chemical, aerospace, petroleum and other fields due to their high strength, wear resistance and corrosion resistance. Si3N4 is a typical high-hardness ceramic material with high hardness and good wear resistance. Zr and Mo are conducive to the formation of carbides and can effectively refine the structure of the LMD layer. Therefore, Si3N4, Zr and Mo are often used as multi-elements to improve the wear resistance of the coating and prepare a multi-element refined wear-resistant protective layer.

[0004] TC17 titanium alloy has the advantages of high specific strength, light weight and excellent corrosion resistance, and is a common material for manufacturing aircraft engines and rocket parts. However, due to the low plastic shear resistance and work hardening rate of TC17 titanium alloy, the surface microhardness of TC17 titanium alloy is low and the wear resistance is poor, which greatly limits the practical application of titanium alloy in industrial production. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the present invention provides a method for preparing a multi-element refined wear-resistant laminate of TC17 titanium alloy by laser, in which a bottom coating and a top coating are sequentially obtained on the surface of TC17 by LMD treatment, and the top coating is located on the bottom coating; the bottom coating is obtained by depositing Stellite31 PM powder and then subjecting it to LMD treatment; the top coating is obtained by mixing Stellite31 PM, Si3N4, Mo, and Zr in a certain proportion on the top of the bottom coating and subjecting it to LMD treatment. Using the method provided by the present invention, a multi-phase coating can be obtained, and the wear resistance is significantly enhanced. The invention has the advantages of simple operation, significant enhancement effect, universal process, and easy promotion and use.

[0006] The technical solution of the present invention is as follows:

[0007] A method for preparing a multi-element refined wear-resistant laminate of TC17 titanium alloy by laser, mainly comprising: sequentially obtaining a bottom coating and a top coating on the surface of TC17 by LMD treatment, wherein the top coating is located on the bottom coating;

[0008] Bottom coating, obtained after deposition of Stellite31 PM powder and LMD treatment;

[0009] The top coating is obtained by mixing Stellite31 PM, Si3N4, Mo, and Zr in a certain proportion on the bottom coating and then treating with LMD.

[0010] Preferably, the above-mentioned method for preparing a multi-element refined wear-resistant laminate of TC17 titanium alloy by laser is as follows:

[0011] (1) TC17 was ground and polished with sandpaper of different coarseness and fineness from coarse to fine until the surface was smooth and free of scratches; then the oxide film was removed and the surface was cleaned and dried;

[0012] (2) Adjusting the laser parameters, and then using the coaxial powder feeding method to deposit Stellite31PM powder on TC17; and at the same time, using 99.9% argon protective gas under this condition, forming a bottom coating after LMD treatment;

[0013] (3) On the top of the bottom coating, a powder mixture of Stellite 31 PM, Si 3 N 4 , Mo, and Zr in a certain proportion is subjected to LMD treatment with the same process parameters as step (2) to form a top coating, thereby having a multi-element refined wear-resistant laminate on TC17.

[0014] Preferably, in step (1), acetone is used to remove the oxide film on the surface of TC17.

[0015] Preferably, the chemical composition (wt%) of TC17 is: Al 4.60%, Mo 4.01%, Zr 1.90%, C 0.02%, 00.107%, Sn 1.72%, Cr 3.81%, N 0.01%, Fe 1%, and the balance Ti;

[0016] Part of the Ti element in TC17 will enter the molten pool due to the dilution effect, and react in situ with the N element, Co element, etc. in the coating to form a hard reinforcement phase, further enhancing the wear resistance.

[0017] Preferably, in step (2), the laser parameters are adjusted to a laser power of 1100-1300 W, a laser beam scanning rate of 13-15 mm / s, a spot diameter of 3 mm, an overlap rate of 25-30%, and Stellite31 PM powder is deposited on TC17 by coaxial powder feeding, with a powder feeding rate of 13 g / min. At the same time, under this condition, 99.9% argon protective gas is used with a flow rate of 30 L / min, and a bottom coating is formed after LMD treatment; argon gas is blown to protect the molten pool and the lens barrel; since the surface of TC17 titanium alloy does not produce strong light reflection, the laser head and the workpiece are kept perpendicular to each other during the experiment.

[0018] Preferably, in step (2), the chemical composition (wt%) of Stellite 31 PM is: C 0.50%, Cr25.50%, Si 1.0%, Mn 1.0%, Fe 2.0%, W 7.50%, Ni 1.50%, B 1.0%; the purity of each component is greater than 99.5%.

[0019] Preferably, in step (3), the top coating composition ratio (wt%) is: Stellite31PM88%, Si3N47%, (Mo-Zr)5%; wherein Mo and Zr have the same mass fraction; the purity of each component is greater than 99.5%; Stellite31PM, Si3N4, Mo, and Zr powders are fully mixed and dried.

[0020] Preferably, the Stellite 31 PM powder has a size between 50 and 200 μm, the Si 3 N 4 powder has a size between 50 and 150 μm, and the Mo and Zr mixed powder has a size between 50 and 100 μm.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] 1. In the present invention, laser melting deposition and coaxial powder feeding are used to prepare a bottom coating on TC17, and a top coating is prepared on the bottom coating, thereby effectively improving the wear resistance of TC17 titanium alloy.

[0023] 2. The method provided by the present invention can be used to obtain a multi-phase coating, and the wear resistance is significantly enhanced. The invention has the advantages of simple operation, obvious enhancement effect, universal process, and easy promotion and use.

[0024] 3. The method provided by the present invention prepares a multi-component refined wear-resistant laminate; the multi-component phase improves the wear resistance of the TC17 surface, and the generated reinforcing phase further enhances the wear resistance through dispersion strengthening. The present invention can obtain an extremely strong wear-resistant laminate on the titanium alloy surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 Metallographic microstructure of LMD stack: (a) TC17 and bottom coating bonding area, (b) bottom coating.

[0027] Figure 2Metallographic microstructure diagram of LMD stack: (a) bonding area between top coating and bottom coating, (b) top coating.

[0028] Figure 3 HRTEM image of the LMD stack.

[0029] Figure 4 (a) The wear volume of the LMD laminate changes with time; (b) The friction coefficient between the laminate and the substrate changes with load. DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments 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 creative work should fall within the scope of protection of the present invention.

[0031] Example 1

[0032] A method for laser preparation of a multi-element refined wear-resistant laminate of TC17 titanium alloy, the steps are as follows:

[0033] (1) TC17 was ground and polished in sequence with 400-mesh, 600-mesh, 800-mesh and 1200-mesh sandpaper from coarse to fine until the surface was smooth and scratch-free; acetone was used to remove the surface oxide film, and then the polished surface was rinsed with clean water, and then cleaned with anhydrous ethanol and dried;

[0034] The chemical composition (wt%) of TC17 is: Al 4.60%, Mo 4.01%, Zr 1.90%, C 0.02%, 00.107%, Sn 1.72%, Cr 3.81%, N 0.01%, Fe 1%, and the balance is Ti;

[0035] (2) The laser parameters were adjusted to a laser power of 1100-1300 W, a laser beam scanning rate of 13-15 mm / s, a spot diameter of 3 mm, an overlap rate of 25-30%, and Stellite31 PM powder was deposited on TC17 by coaxial powder feeding at a powder feeding rate of 13 g / min. Under the same conditions, 99.9% argon protective gas was used at a flow rate of 30 L / min to form a bottom coating after LMD treatment;

[0036] Chemical composition of Stellite31 PM (wt%): C 0.50%, Cr 25.50%, Si 1.0%, Mn 1.0%, Fe 2.0%, W 7.50%, Ni 1.50%, B 1.0%; the purity of each component is greater than 99.5%;

[0037] (3) Stellite 31 PM, Si 3 N 4, Mo, and Zr powders are mixed in proportion to form a mixed powder having a mass fraction ratio of Stellite 31 PM 88%, Si 3 N 4 7%, and (Mo-Zr) 5%, wherein the mass fractions of Mo and Zr are the same, and the purity of each component is greater than 99.5%; the mixed powder is treated by LMD using the same process and parameters as step (2) to form a top coating on the bottom coating;

[0038] The powder size of Stellite31 PM is between 50-200μm, the powder size of Si3N4 is between 50-150μm, and the powder size of Mo and Zr mixed is between 50-100μm.

[0039] In the present invention, TC17 titanium alloy is subjected to LMD treatment, and Stellite31PM powder is deposited on the surface of TC17 substrate by coaxial powder feeding to form a bottom coating, and Stellite31 PM, Si3N4, Mo, and Zr are mixed according to proportion, and then the mixture is LMDed on the bottom coating to form a top coating by LMD technology; the purity of each component is greater than 99.5%; the size of Stellite31PM powder is controlled to be 50-200μm, the size of Si3N4 powder is 50-150μm, and the size of Mo and Zr mixed powder is 50-100μm;

[0040] Combination Figure 1 a It can be seen that the bottom coating has a good metallurgical bond with the substrate, and there are a large number of columnar crystals growing perpendicular to the boundary near the coating side of the bonding area;

[0041] Combination Figure 1 b It can be seen that the bottom coating is composed of a large number of dendrites with different growth directions, and fine generated phases are dispersed between the dendrites;

[0042] Combination Figure 2 a It can be seen that the top coating and the bottom coating are metallurgically bonded, and no obvious defects are generated;

[0043] Combination Figure 2 As can be seen from b, the top coating has a dense and fine structure, and the fine generated phases are significantly increased and evenly distributed.

[0044] like Figure 3 As shown in the figure, the bottom coating formed by LMD Stellite31 PM is composed of a large number of nanocrystals and amorphous materials, which further confirms the grain refinement effect. Due to the extremely fast cooling speed of the LMD molten pool, it is easy to form a multi-element refined structure.

[0045] Figure 4 a shows that the wear volume of the LMD laminate is relatively small, indicating that the laminate has good wear resistance;

[0046] Figure 4 b It is confirmed that the friction coefficient of TC17 is higher than that of the coating. With the increase of applied load, the friction coefficient of the laminate decreases all the time, and the wear resistance of the laminate is significantly better than that of TC17. Combined with the analysis of the microstructure of the laminate, the dense and fine microstructure can hinder the dislocation movement to achieve fine grain strengthening. The nanocrystals and amorphous materials in the prepared laminate have high strength and strong wear resistance. Cobalt-based and ceramic Si3N4 are treated with LMD to generate hard phases, and Mo and Zr elements promote the formation of carbides to produce dispersion strengthening, that is, these products are dispersed to hinder friction movement, thereby improving wear resistance.

[0047] in addition, Figure 4 b Friction coefficient proves that the friction coefficient of the wear-resistant laminate is significantly smaller than that of the substrate, proving that the wear resistance of the prepared laminate is significantly enhanced compared with the substrate.

[0048] Based on the above analysis, it can be seen that the use of LMD to prepare Stellite31 PM-based multi-element refined wear-resistant laminate on the surface of TC17 titanium alloy can significantly enhance the wear resistance of the titanium alloy surface.

[0049] Although the present invention has been described in detail by reference to the 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 these modifications or substitutions shall be within the scope of the present invention. Any person of ordinary skill in the art may easily think of changes or substitutions within the technical scope disclosed by the present invention, and these shall be within 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 preparing a multi-element fine wear-resistant laminate of TC17 titanium alloy by laser, characterized in that: The process is as follows: (1) Use sandpaper of different coarseness and fineness to grind and polish TC17 from coarse to fine until the surface is smooth and scratch-free; then remove the oxide film and clean and dry it; (2) Adjust the laser parameters and then deposit Stellite31 PM powder on TC17 using coaxial powder feeding; During the deposition process, 99.9% argon protective gas was used, and the bottom coating was formed after LMD treatment; (3) LMD treatment is performed on the bottom coating using a mixed powder of Stellite 31 PM, Si3N4, Mo, and Zr. The process parameters of the LMD treatment are the same as those in step (2) to form a top coating, thereby having a multi-element refined wear-resistant laminate on TC17; Wherein, in step (2), the laser parameters are: laser power 1100-1300W, laser beam scanning rate 13-15mm / s, spot diameter 3mm, overlap rate 25-30%; The composition ratio (wt%) of the top coating is: Stellite31 PM 88%, Si3N4 7%, (Mo-Zr) 5%; wherein the mass fractions of Mo and Zr are the same; the purity of each component is greater than 99.5%; Stellite31 PM, Si3N4, Mo, and Zr powders are fully mixed and dried.

2. The method for preparing TC17 titanium alloy multi-element refined wear-resistant laminate by laser according to claim 1, characterized in that: In step (1), acetone is used to remove the oxide film on the surface of TC17.

3. The method for preparing a multi-element refined wear-resistant laminate of TC17 titanium alloy by laser according to claim 1, characterized in that: The chemical composition (wt%) of the TC17 is: Al 4.60%, Mo 4.01%, Zr 1.90%, C 0.02%, O 0.107%, Sn 1.72%, Cr 3.81%, N 0.01%, Fe 1%, and the balance Ti.

4. The method for preparing a multi-element refined wear-resistant laminate of TC17 titanium alloy by laser according to claim 3, characterized in that: In step (2), Stellite 31 PM powder was deposited on TC17 by coaxial powder feeding at a powder feeding rate of 13 g / min. Under the same conditions, 99.9% argon protective gas was used at a flow rate of 30 L / min. After LMD treatment, a bottom coating was formed.

5. The method for preparing TC17 titanium alloy multi-element refined wear-resistant laminate by laser according to claim 3, characterized in that: The Stellite 31 PM powder has a size between 50 and 200 μm, the Si 3 N 4 powder has a size between 50 and 150 μm, and the Mo and Zr mixed powder has a size between 50 and 100 μm.

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