TiAl alloy surface Ni coating and preparation method thereof

Abstract

The invention discloses a TiAl alloy surface Ni coating and a preparation method thereof, and belongs to the technical field of surface treatment.The preparation method comprises the steps that a TiAl alloy base material is prepared, and the surface of the TiAl alloy base material is pretreated; the pretreated TiAl alloy matrix material is placed in a nickel plating electrolyte for electro-deposition nickel plating, and a Ni coating covering the surface of the TiAl alloy matrix material is obtained; wherein the nickel plating electrolyte comprises a nickel-containing basic electrolyte and an additive, and the additive is used for improving the surface flatness and smoothness of the Ni coating. According to the method, electrodeposition nickel plating is carried out on the surface of the TiAl alloy, and the technical effect of improving the surface quality of a plating layer is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of surface treatment, and particularly relates to a Ni coating on the surface of a TiAl alloy and a preparation method thereof. Background Art

[0002] As an advanced material applicable to hot-end components, the TiAl alloy has the performance characteristics of light weight and high strength, but has poor wear resistance and needs surface treatment to improve its wear resistance.

[0003] Electrodepositing nickel is a surface coating technology mainly used to improve the surface hardness, corrosion resistance, smoothness and conductivity of materials. The basic principle of nickel electrodeposition is that under the action of the electric field between the anode and the cathode, nickel ions (positively charged) in the electroplating solution migrate directionally to the cathode, obtain electrons at the cathode and deposit on the surface of the metal electrode. Compared with other coating technologies, electrodeposition has the advantages of simplicity, low cost, relatively stable and efficient, being applicable to conductive materials, and being able to obtain single-layer or composite coatings that are tightly bonded to the substrate. However, the existing electrodepositing nickel technology on the surface of the TiAl alloy uses Watt solution as the electrolyte, and there are problems such as slow coating deposition rate, large grain size, and poor surface quality. Summary of the Invention

[0004] The main purpose of the present invention is to provide a Ni coating on the surface of a TiAl alloy and a preparation method thereof, aiming to solve the technical problems of slow deposition rate and poor surface quality of the nickel coating on the surface of the TiAl alloy.

[0005] To achieve the above object, the present invention provides a preparation method for a Ni coating on the surface of a TiAl alloy, including:

[0006] Preparing a TiAl alloy substrate material and performing pretreatment on the surface of the TiAl alloy substrate material;

[0007] Placing the pretreated TiAl alloy substrate material in a nickel electroplating electrolyte and performing electrodepositing nickel to obtain a Ni coating covering the surface of the TiAl alloy substrate material;

[0008] Wherein, the nickel electroplating electrolyte includes a nickel-containing basic electrolyte and an additive, and the additive is used to improve the surface smoothness of the Ni coating.

[0009] In one embodiment, the TiAl alloy substrate material is a γ-TiAl alloy, which, in atomic percentage, includes 42-48% of Al, 0-10% of alloying elements, 0-1% of trace elements, and the balance is Ti;

[0010] The alloying elements include at least one of Mn, Nb, W, Mo, Ta, Cr, V, Zr, Hf, Si;

[0011] The trace elements include at least one of C and B.

[0012] In one embodiment, the step of pretreating the surface of the TiAl alloy matrix material includes:

[0013] Grind the surface of the TiAl alloy matrix material to 2000 mesh;

[0014] Ultrasonically clean the ground TiAl alloy matrix material, and then place it in an alkaline solution for chemical degreasing treatment. The temperature of the chemical degreasing treatment is 60 - 80°C, and the time of the chemical degreasing treatment is 30 - 60 sec;

[0015] Place the TiAl alloy matrix material after chemical degreasing treatment in a first acidic solution for etching treatment. The temperature of the etching treatment is 60 - 80°C, and the time of the etching treatment is 30 - 120 sec;

[0016] Place the TiAl alloy matrix material after etching treatment in a second acidic solution for brightening treatment. The temperature of the brightening treatment is at room temperature, and the time of the brightening treatment is 2 - 20 sec.

[0017] In one embodiment, the alkaline solution includes: sodium hydroxide with a concentration of 15 - 20 g / L, sodium carbonate with a concentration of 40 - 60 g / L, sodium phosphate with a concentration of 20 - 30 g / L, and distilled water.

[0018] In one embodiment, the first acidic solution includes: concentrated sulfuric acid with a concentration of 60 - 120 ml / L, chromium trioxide with a concentration of 20 - 50 g / L, and distilled water.

[0019] In one embodiment, the second acidic solution includes: nitric acid with a concentration of 200 - 500 ml / L, hydrofluoric acid with a concentration of 50 - 100 ml / L, and distilled water.

[0020] In one embodiment, the nickel - containing basic electrolyte includes: nickel sulfamate with a concentration of 380 - 500 g / L, nickel chloride or sodium chloride with a concentration of 2 - 10 g / L, and boric acid with a concentration of 35 - 45 g / L;

[0021] And / or, the additive includes: sodium benzenesulfinate with a concentration of 0.02 - 0.10 g / L, 1,4 - butynediol with a concentration of 0.1 - 0.3 g / L, sodium allylsulfonate with a concentration of 0.2 - 0.8 g / L, and sodium dodecyl sulfate with a concentration of 0.05 - 0.20 g / L.

[0022] In one embodiment, the electrodeposited nickel plating uses a DC stable power supply, and the current density is 1 - 4 A / dm 2, the temperature is 50 - 60 °C, and the treatment time is 10 - 40 min.

[0023] In one embodiment, the thickness of the Ni coating is 4 - 20 μm; and / or, the microhardness of the Ni coating ≥ 400 HV.

[0024] In addition, to achieve the above object, the present invention also provides a Ni coating on the surface of a TiAl alloy, and the Ni coating on the surface of the TiAl alloy is prepared by using the preparation method of the Ni coating on the surface of the TiAl alloy as described above.

[0025] The preparation method of the Ni coating on the surface of the TiAl alloy provided by the present invention first pretreats the TiAl alloy substrate material to remove the dense oxide layer on the surface of the TiAl alloy substrate material, making the surface of the TiAl alloy substrate material smoother. The pretreated TiAl alloy substrate material is placed in a nickel plating electrolyte, and the TiAl alloy substrate material serves as the cathode, and the nickel-based electrolyte in the nickel plating electrolyte serves as the source of nickel ions. The nickel ions reach the surface of the TiAl alloy substrate material under the action of an electric current and deposit to form a Ni coating. Since the present invention uses nickel sulfamate as the source of nickel ions, the current efficiency in the electroplating process is improved, thereby increasing the coating deposition rate. And due to the addition of additives, the surface smoothness, microhardness of the coating and the bonding force between it and the substrate can be significantly improved, and the quality of the Ni coating on the surface of the TiAl alloy is improved. Description of the Drawings

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present drawings or related technologies, the following will briefly introduce the drawings required to be used in the description of the embodiments or related technologies. Obviously, the following drawings are only some embodiments of the present drawings. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the structures shown in these drawings.

[0027] Figure 1 It is the coating morphology diagram under the scanning electron microscope provided by the embodiment of the present invention;

[0028] Figure 2 It is the schematic diagram of the scratch test result provided by the embodiment of the present invention.

[0029] The realization, functional features and advantages of the object of the present invention will be further described in conjunction with the embodiments with reference to the drawings. Detailed Embodiments

[0030] It should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention. Hereinafter, embodiments of the Ni coating on the TiAl alloy surface and its preparation method of the present invention specifically disclosed will be described in detail with reference to the accompanying drawings as appropriate. However, there may be cases where unnecessary details are omitted. For example, there are cases where details of well-known matters are omitted and repeated descriptions of actually identical structures are omitted. This is to prevent the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the accompanying drawings and the following description are provided for those skilled in the art to fully understand the present invention and are not intended to limit the subject matter recited in the claims.

[0031] The "range" disclosed in the present invention is defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a particular range. The range defined in this way can include the end values or not include the end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is understood that ranges of 60-110 and 80-120 are also contemplated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In the present invention, unless otherwise specified, the numerical range "a-b" represents an abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been fully listed herein, and "0-5" is only an abbreviated representation of these numerical combinations. In addition, when it is stated that a certain parameter is an integer ≥2, it is equivalent to disclosing that the parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0032] To make the above objects, features, and advantages of the present invention more obvious and understandable, the technical solutions of the present invention will be further described below with reference to the accompanying drawings and embodiments. However, the present invention is not limited to the listed embodiments and should also include any other well-known changes within the scope of the rights required by the present invention.

[0033] Currently, the components of the nickel plating solution in titanium alloys mostly include nickel sulfate and nickel chloride. For example, the components of the nickel plating solution used in the electroplating of related titanium-nickel-based memory alloys: nickel sulfate heptahydrate, hydrochloric acid, glacial acetic acid, and nickel chloride (NiCl 2)。In the electroplating on the surface of titanium alloy in related technologies, a non-aqueous pre-electroplating solution is used for the coating, with ethylene glycol as the solvent, containing nickel chloride, boric acid, ammonium bifluoride, citric acid, and phosphoric acid. In the process of directly electroplating nickel on titanium alloy TC4, TC4 is electroplated in a Watts solution (a solution mainly composed of nickel sulfate, nickel chloride, and boric acid). In the nickel plating solution for aluminum alloy, the composition is similar to that of the nickel plating solution for titanium alloy, and the plating solution mainly includes nickel sulfate and nickel chloride.

[0034] Compared with titanium alloy and aluminum alloy, the research on the electrodeposited Ni coating on the surface of TiAl alloy is less, and mostly the Watts solution is used as the plating solution. However, the deposition rate of this plating solution coating is relatively slow (about 5 μm / h), which cannot meet the production requirements. At the same time, the introduction of additives in the research is relatively less, while the dependence on additives in nickel plating is extremely high, and additives play a decisive role in ensuring the quality of nickel plating and the stability of the nickel plating solution.

[0035] Based on this, the embodiment of the present invention provides a method for preparing a Ni coating on the surface of TiAl alloy. In this embodiment, the method for preparing the Ni coating on the surface of TiAl alloy includes steps S10 - S20:

[0036] Step S10, prepare a TiAl alloy substrate material and perform pretreatment on the surface of the TiAl alloy substrate material;

[0037] It can be understood that TiAl alloy is an alloy mainly composed of Ti element and Al element, and these two elements account for a very large proportion in the alloy. While Ti alloy and Al alloy are alloys mainly composed of Ti element and Al element respectively as the main alloying elements. Due to the difference in alloy composition, the properties of TiAl alloy are also different from most Ti alloys and Al alloys. Under the environmental conditions of contact with air, various alloys will form oxide films on the surface. And the oxide film on the surface of TiAl alloy is TiO 2 and Al 2 O 3 mixture. Therefore, it is necessary to remove the oxide film on the surface of the TiAl alloy substrate material through the pretreatment step so that nickel ions can adhere better.

[0038] In a feasible embodiment, the TiAl alloy substrate material is γ-TiAl alloy, which, in atomic percentage, includes 42 - 48% of Al, 0 - 10% of alloying elements, 0 - 1% of trace elements, and the balance is Ti; the alloying elements include at least one of Mn, Nb, W, Mo, Ta, Cr, V, Zr, Hf, Si; the trace elements include at least one of C, B. γ-TiAl alloy is a lightweight high-temperature material and can be used in the aerospace field to manufacture high-temperature structural parts. The alloying elements and trace elements added to TiAl alloy can regulate the properties of the alloy to meet different usage requirements.

[0039] In a feasible implementation, the steps of the pretreatment include steps S11 - S14:

[0040] Step S11, polish the surface of the TiAl alloy matrix material to 2000 mesh;

[0041] The surface of the TiAl alloy matrix material can be gradually polished using sandpapers with different roughnesses to control the surface roughness of the TiAl alloy matrix material to 2000 mesh. Polishing is a physical surface treatment method that can quickly break and remove most of the oxide film.

[0042] Step S12, ultrasonically clean the polished TiAl alloy matrix material, and then place it in an alkaline solution for chemical degreasing treatment. The temperature of the chemical degreasing treatment is 60 - 80 °C, and the time of the chemical degreasing treatment is 30 - 60 sec;

[0043] The polished TiAl alloy matrix material can be ultrasonically cleaned in absolute ethanol and distilled water for 10 min each, and then placed in an alkaline solution for chemical degreasing treatment. It can be understood that grease is usually formed by higher fatty acids and glycerol, and hot alkaline solutions have a saponification effect on grease, which can promote the dissolution of grease. The temperature of the chemical degreasing treatment is in the range of 60 - 80 °C, for example, 60 °C, 65 °C, 70 °C, 75 °C, 80 °C, etc., and the time of the chemical degreasing treatment is in the range of 30 - 60 sec, for example, 30 sec, 40 sec, 50 sec, 60 sec, etc. Providing a certain temperature condition can accelerate the dissolution rate of grease and improve the treatment efficiency.

[0044] Optionally, the alkaline solution includes: sodium hydroxide with a concentration of 15 - 20 g / L, sodium carbonate with a concentration of 40 - 60 g / L, sodium phosphate with a concentration of 20 - 30 g / L, and distilled water. Sodium hydroxide, sodium carbonate, and sodium phosphate are all alkaline substances, and they can all provide alkaline conditions for chemical degreasing treatment. Among them, sodium hydroxide and sodium carbonate have stronger alkalinity and lower costs, and sodium phosphate can also play a role in buffering the pH value of the solution. According to the characteristics of the TiAl alloy matrix material, the above combination of alkaline solutions is selected and appropriate concentrations are set to meet the requirements of degreasing.

[0045] Step S13, place the TiAl alloy matrix material after chemical degreasing treatment in a first acidic solution for etching treatment. The temperature of the etching treatment is 60 - 80 °C, and the time of the etching treatment is 30 - 120 sec;

[0046] The TiAl alloy matrix material after chemical degreasing treatment can be placed in distilled water and ultrasonically cleaned for 10 min to wash away the residual alkaline solution on the surface of the TiAl alloy matrix material, and then etching treatment is carried out. It can be understood that if microscopic observation is carried out on the surface of the TiAl alloy matrix material after physical polishing, it will still be found that the surface is rough. Through etching treatment, the surface roughness can be further reduced and the remaining oxide film can be removed. The temperature of the etching treatment is controlled within the range of 60-80 °C, for example, 60 °C, 65 °C, 70 °C, 75 °C, 80 °C, etc., and the time of the etching treatment is within the range of 30-120 sec, for example, 30 sec, 45 sec, 60 sec, 90 sec, 100 sec, 115 sec, 120 sec, etc. Within a suitable temperature range, the etching speed can be accelerated, and the purpose of removing the oxide film and smoothing the surface can be achieved in a short time.

[0047] Optionally, the first acidic solution includes: concentrated sulfuric acid with a concentration of 60-120 ml / L, chromium trioxide with a concentration of 20-50 g / L, and distilled water. Concentrated sulfuric acid with a mass content of 98% can be used to prepare the first acidic solution. Sulfuric acid can provide an acidic environment, chromium trioxide has strong oxidizing properties, and there is a synergistic effect between concentrated sulfuric acid and chromium trioxide. The components in the oxide film react with acidic substances to generate substances such as aluminum ions and dissolve in the solution, thereby removing the oxide film.

[0048] Step S14, placing the etched TiAl alloy matrix material in a second acidic solution for brightening treatment, the temperature of the brightening treatment is room temperature, and the time of the brightening treatment is 2-20 sec.

[0049] The etched TiAl alloy matrix material can be placed in distilled water and ultrasonically cleaned for 10 min to wash away substances such as the residual first acidic solution on the surface of the TiAl alloy matrix material, and then brightening treatment is carried out. The brightening treatment can further remove the residual oxides and protrusions on the surface of the TiAl alloy matrix material, make the surface smoother, and thus improve the bonding force between the coating and the matrix. The brightening treatment can be carried out at room temperature, and the treatment time is within the range of 2-20 sec, for example, 2 sec, 5 sec, 8 sec, 10 sec, 12 sec, 15 sec, 20 sec, etc. Controlling the time of the brightening treatment within a suitable range can reduce the surface roughness and improve the bonding force between the coating and the TiAl alloy matrix.

[0050] Optionally, the second acidic solution includes: nitric acid with a concentration of 200-500 ml / L, hydrofluoric acid with a concentration of 50-100 ml / L, and distilled water. Both nitric acid and hydrofluoric acid can provide an acidic environment and react with the components in the oxide film.

[0051] Step S20: Place the pretreated TiAl alloy matrix material in a nickel plating electrolyte for electrodeposition nickel plating to obtain a Ni coating covering the surface of the TiAl alloy matrix material.

[0052] It can be understood that the nickel plating electrolyte contains nickel ions. During the electrodeposition nickel plating process, the TiAl alloy matrix material serves as the cathode. Driven by the current, the positively charged nickel ions attach to the surface of the TiAl alloy matrix material to form a Ni coating.

[0053] Optionally, the nickel-containing basic electrolyte includes: nickel sulfamate with a concentration of 380 - 500 g / L, nickel chloride or sodium chloride with a concentration of 2 - 10 g / L, and boric acid with a concentration of 35 - 45 g / L. The additives include: sodium benzenesulfinate with a concentration of 0.02 - 0.10 g / L, 1,4 - butynediol with a concentration of 0.1 - 0.3 g / L, sodium allylsulfonate with a concentration of 0.2 - 0.8 g / L, and sodium dodecyl sulfate with a concentration of 0.05 - 0.20 g / L.

[0054] In the basic electrolyte, nickel sulfamate is the main salt that provides nickel ions. It has the largest concentration, provides sufficient nickel ions for electroplating, and has a relatively high deposition rate, which can improve production efficiency and reduce the internal stress of the coating. The spatial volume of the sulfamate anion is relatively small and can form complexes under certain conditions, being dense in the solution. Nickel chloride or sodium chloride acts as a conductive salt and an anode activator in the electrolyte, which can improve the dispersion ability and conductivity of the electrolyte. Nickel chloride can also supplement the consumption of metal nickel ions in the electrolyte. The content of these chlorides such as nickel chloride or sodium chloride should be controlled within a certain range to avoid coating quality problems caused by anode passivation or too fast anode dissolution. Boric acid plays a buffering role and can stabilize the pH value of the electrolyte, and can only play a buffering role within a certain concentration range.

[0055] The above additives can all reduce the surface tension of the electrolyte, making the gas generated during the electrodeposition process easy to precipitate and preventing holes from being formed on the surface of the TiAl alloy matrix material. Among them, 1,4 - butynediol serves as an electroplating brightener, which can improve the brightness of the nickel coating to a certain extent. When used in combination with other additives, the obtained Ni coating is flat and bright, and the surface quality is improved.

[0056] In a feasible implementation manner, direct current stable power supply is used for electrodeposition nickel plating, and the current density is 1 - 4 A / dm 2 , for example, 1 A / dm 2 , 2 A / dm 2 , 3 A / dm 2 , 4 A / dm 2etc., the temperature is 50 - 60 °C, for example, 50 °C, 52 °C, 52 °C, 55 °C, 58 °C, 60 °C, etc., and the treatment time is 10 - 40 min, for example, 10 min, 20 min, 30 min, 40 min, etc. The greater the current density, the faster the electrodeposition rate of nickel plating. Maintaining within a suitable current density range can accelerate the deposition rate and reduce energy waste.

[0057] In this embodiment, the TiAl alloy substrate material is pretreated first to remove the dense oxide layer on the surface of the TiAl alloy substrate material, making the surface of the TiAl alloy substrate material smoother. The pretreated TiAl alloy substrate material is placed in a nickel plating electrolyte. The TiAl alloy substrate material serves as the cathode, and the nickel-containing basic electrolyte in the nickel plating electrolyte serves as the source for providing nickel ions. The nickel ions reach the surface of the TiAl alloy substrate material under the action of an electric current and deposit to form a Ni coating. Moreover, due to the addition of additives, the surface smoothness, microhardness of the coating, and the bonding force between it and the substrate can be significantly improved, enhancing the quality of the Ni coating on the TiAl alloy surface.

[0058] The embodiment of the present invention also provides a Ni coating on the TiAl alloy surface, which is prepared by using the preparation method of the Ni coating on the TiAl alloy surface described in the above embodiment. The thickness of the Ni coating prepared by the method of the above embodiment is 4 - 20 μm, for example, 4 μm, 5 μm, 10 μm, 15 μm, 20 μm, etc. A certain thickness can ensure the stability of the coating and play a role in protecting the internal substrate material. The microhardness of the Ni coating ≥ 400 HV, for example, 400 HV, 415 HV, 430 HV, etc. Therefore, the Ni coating prepared by electrodeposition nickel plating on the surface of the TiAl alloy substrate material in the embodiment of the present invention has a good bonding force with the substrate, and also has a relatively high hardness, and the coating quality is significantly improved.

[0059] The following elaborates on the Ni coating on the TiAl alloy surface and its preparation method of the present invention in detail with specific embodiments.

[0060] Example 1

[0061] Material preparation:

[0062] The material used is γ-TiAl alloy. In atomic percentage, its composition includes 42.0% Al, 5.0% Mn, 0.1% W, 0.1% Mo, 0.1% C, and the balance is Ti.

[0063] Material pretreatment:

[0064] Before electroplating, the surface of the TiAl alloy material is polished with SiC sandpaper to 2000 mesh, and the polished TiAl alloy material is placed in distilled water and ultrasonically cleaned for 10 min.

[0065] The cleaned TiAl alloy material is placed in an alkaline solution for chemical degreasing at a temperature of 72 °C for 50 s. The alkaline solution is as follows: the concentration of sodium hydroxide is 17.5 g / L, the concentration of sodium carbonate is 45 g / L, the concentration of sodium phosphate is 27.5 g / L, and the balance is distilled water.

[0066] The degreased TiAl alloy material is ultrasonically cleaned with distilled water for 10 min and then placed in a first acidic solution for etching at a temperature of 72 °C for 65 s. The first acidic solution is as follows: the concentration of concentrated sulfuric acid (98%) is 100 ml / L, the concentration of chromium trioxide is 35 g / L, and the balance is distilled water.

[0067] The etched TiAl alloy material is ultrasonically cleaned with distilled water for 10 min and then placed in a second acidic solution for brightening at room temperature for 5 s. The second acidic solution is as follows: the concentration of nitric acid is 400 ml / L, the concentration of hydrofluoric acid is 80 ml / L, and the balance is distilled water.

[0068] TiAl electroplated Ni coating:

[0069] TiAl is electroplated using a DC stabilized power supply with a current density of 2 A / dm 2 , at a temperature of 55 °C for 25 min. The nickel plating electrolyte used for electroplating Ni includes a nickel-containing basic electrolyte and additives. Among them, the basic electrolyte is: 400 g / L nickel sulfamate, 4 g / L nickel chloride, 40 g / L boric acid. The additives are: 0.05 g / L sodium benzenesulfinate, 0.2 g / L 1,4-butyne diol, 0.5 g / L allylsulfonic acid sodium salt, 0.1 g / L sodium dodecyl sulfate.

[0070] Coating analysis:

[0071] Coating hardness: The Vickers hardness of the specimen is measured using a Vickers hardness tester with a load of 300 g, a holding time of 10 s, and 10 points are tested. The average hardness is 419.4 HV.

[0072] Coating thickness: The surface morphology of the coating is observed and analyzed using a scanning electron microscope and a metallurgical microscope. Figure 1 is the coating morphology diagram under the scanning electron microscope, as Figure 1 shown, the coating has good compactness, a flat and smooth surface, and the coating thickness is 10 μm.

[0073] Coating adhesion: The coating adhesion is tested using a scratch tester with a loading speed of 100 N / min, a maximum load of 150 N, and a scratch length of 15 mm. Figure 2 is the scratch test result diagram, as Figure 2As shown, the test results of the scratch pictures show that the coating cracking load (L c2 ) is 65 N.

[0074] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied to other related technical fields, shall be equally included in the patent protection scope of the present invention.

Claims

1. A method for preparing a Ni coating on a TiAl alloy surface, characterized in that: The method for preparing the Ni coating on the surface of the TiAl alloy comprises the following steps: Preparing a TiAl alloy matrix material, and pre-treating the surface of the TiAl alloy matrix material; Placing the pre-treated TiAl alloy substrate material in a nickel plating electrolyte to perform nickel electroplating to obtain a Ni coating covering the surface of the TiAl alloy substrate material; The nickel plating electrolyte comprises a nickel-containing basic electrolyte and an additive, and the additive is used to improve the surface flatness and smoothness of the Ni coating.

2. The method for preparing a Ni coating on a TiAl alloy surface as claimed in claim 1, characterized in that: The TiAl alloy matrix material is a γ-TiAl alloy, which, in terms of atomic percentage, comprises 42-48% Al, 0-10% alloying elements, 0-1% trace elements, and the balance is Ti; The alloying element includes at least one of Mn, Nb, W, Mo, Ta, Cr, V, Zr, Hf, and Si; The trace elements include at least one of C and B.

3. The method for preparing a Ni coating on a TiAl alloy surface as claimed in claim 1, characterized in that: The step of pre-treating the surface of the TiAl alloy matrix material comprises: Grinding the surface of the TiAl alloy substrate to 2000 mesh; The polished TiAl alloy substrate material is ultrasonically cleaned, and then placed in an alkaline solution for chemical degreasing treatment, wherein the temperature of the chemical degreasing treatment is 60-80° C., and the time of the chemical degreasing treatment is 30-60 seconds; Placing the TiAl alloy substrate after chemical degreasing treatment in a first acidic solution for etching treatment, wherein the etching treatment temperature is 60-80° C. and the etching treatment time is 30-120 seconds; The TiAl alloy matrix material after the corrosion treatment is placed in a second acidic solution for light treatment. The temperature of the light treatment is room temperature and the time of the light treatment is 2-20 seconds.

4. The method for preparing a Ni coating on a TiAl alloy surface as claimed in claim 3, characterized in that: The alkaline solution comprises: sodium hydroxide with a concentration of 15-20 g / L, sodium carbonate with a concentration of 40-60 g / L, sodium phosphate with a concentration of 20-30 g / L and distilled water.

5. The method for preparing a Ni coating on a TiAl alloy surface as claimed in claim 3, characterized in that: The first acidic solution includes: concentrated sulfuric acid with a concentration of 60-120 ml / L, chromium trioxide with a concentration of 20-50 g / L, and distilled water.

6. The method for preparing a Ni coating on a TiAl alloy surface as claimed in claim 3, characterized in that: The second acidic solution includes: nitric acid with a concentration of 200-500 ml / L, hydrofluoric acid with a concentration of 50-100 ml / L, and distilled water.

7. The method for preparing a Ni coating on a TiAl alloy surface as claimed in claim 1, characterized in that: The nickel-containing basic electrolyte comprises: nickel sulfamate with a concentration of 380-500 g / L, nickel chloride or sodium chloride with a concentration of 2-10 g / L, and boric acid with a concentration of 35-45 g / L; And / or, the additives include: sodium benzenesulfinate with a concentration of 0.02-0.10 g / L, 1,4-butynediol with a concentration of 0.1-0.3 g / L, sodium allylsulfonate with a concentration of 0.2-0.8 g / L, and sodium dodecyl sulfate with a concentration of 0.05-0.20 g / L.

8. The method for preparing a Ni coating on a TiAl alloy surface as claimed in claim 1, characterized in that: The electroplating nickel adopts a DC stable power supply with a current density of 1-4A / dm 2 , temperature is 50-60℃, and processing time is 10-40min.

9. The method for preparing a Ni coating on a TiAl alloy surface as claimed in any one of claims 1 to 8, characterized in that: The thickness of the Ni coating is 4-20 μm; and / or the microhardness of the Ni coating is ≥400 HV.

10. A Ni coating on the surface of a TiAl alloy, characterized in that: The Ni coating on the surface of the TiAl alloy is prepared by the method for preparing the Ni coating on the surface of the TiAl alloy according to any one of claims 1 to 9.

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