Acid electroplating method for preparing platinum plating layer on surface of nickel-based high-temperature alloy

Abstract

The invention provides a method for preparing a platinum (Pt) coating on the surface of a nickel-based superalloy, which comprises the following steps of: sequentially polishing, deoiling, pickling and washing the surface of the nickel-based superalloy to obtain the treated nickel-based superalloy; and the treated nickel-based superalloy is subjected to Pt electroplating treatment. Wherein the electroplating liquid comprises 5-10 g / L of platinum dichloride, 80-120 g / L of potassium chloride and 0.1-0.2 g / L of sodium glutamate on the basis of platinum, and according to the electroplating process, the electroplating time is 1.5-3 H, the current density is 0.5-1.5 A / dm, the temperature is 25-65 DEG C, and the pH value is 1-2.5. According to the invention, platinum dichloride is used as a main salt, potassium chloride is used as an auxiliary salt, and sodium glutamate is used as a brightener, so that the obtained coating has the advantages of small internal stress, compact structure and smooth surface. A plating layer obtained by electroplating under an acidic condition by adopting the electroplating solution is high in binding force and low in porosity.

Description

Technical Field

[0001] The invention relates to the technical field of platinum electroplating, and in particular to an acid electroplating method for preparing a platinum coating on the surface of a nickel-based high-temperature alloy. Background Art

[0002] With the continuous development of China's science and technology, the requirements of the aviation industry are getting higher and higher, and the requirements for the use of turbine engines are also rising rapidly. Under increasingly harsh service requirements, metal materials used as turbine blades must have extremely high high temperature performance and excellent resistance to thermal corrosion and oxidation. Nickel-based high-temperature alloy is an austenitic alloy with nickel as the matrix, which has high strength in the temperature range of 650-1200°C. However, at this temperature, it is difficult to have both excellent mechanical properties and strong high-temperature chemical stability. The current solution is to coat a high-temperature protective layer on the surface of nickel-based high-temperature alloys. High-temperature alloy turbine blades were originally adopted because of the low price and stable performance of aluminized coatings, but there are two main problems with this coating: first, its use temperature is limited to below 1000°C; second, the coating plasticity is not ideal and it is easy to peel off during service.

[0003] Currently, most mainstream electroplating processes are carried out in an alkaline electroplating environment, but the coating produced by the alkaline electroplating solution has poor bonding strength and poor coating quality. Summary of the invention

[0004] In view of this, the present invention provides, on one hand, an acid electroplating method for preparing a platinum coating on the surface of a nickel-based high-temperature alloy. The coating obtained by the electroplating method has good bonding strength and high coating quality.

[0005] An acidic platinum-plating electroplating solution comprises, based on platinum, 5-10 g / L of platinum dichloride, 80-120 g / L of potassium chloride, and 0.1-0.2 g / L of sodium glutamate.

[0006] Among them, it further contains 8g / L platinum dichloride, 100g / L potassium chloride, and 0.18g / L sodium glutamate in terms of platinum.

[0007] In this electroplating solution, platinum dichloride is selected as the main salt, and the molecular formula is PtCl 2. When the platinum ion content is low, the coating is gray or even black. Increasing the main salt content can correspondingly increase the cathode current density and accelerate the deposition rate. However, due to the extremely high platinum price, the platinum content must be strictly controlled within the range of 5-10g / L. Too high a main salt can easily make the coating rough; potassium chloride is a conductive salt and also a common ion effect salt, which can prevent the main salt from decomposing and improve the conductivity of the solution; sodium glutamate is a brightener, and 0.1-0.2g / L sodium glutamate can make the coating bright; if a thicker coating is to be obtained, the cathode needs to be moved frequently, and the plated parts need to be taken out several times in the middle, the burrs need to be wiped off and then plated. Due to the continuous increase of micro-strain, the coating thickness obtained in this type of electroplating solution is limited.

[0008] In addition to the above-mentioned components, the present invention may also use other additives commonly used in the art, such as conventional additives such as auxiliary salts, in appropriate amounts, which will not damage the properties of the coating.

[0009] Another aspect of the present invention provides an electroplating process, wherein the coating prepared by the process has higher quality.

[0010] A method for electroplating using the above electroplating solution comprises the following steps:

[0011] S1: preparing a plating solution: dissolving various raw material components in water to form a plating solution, wherein each liter of the plating solution contains 5-10 g / L of platinum dichloride, 80 g / L of potassium chloride, and 0.1-0.2 g / L of sodium glutamate in terms of platinum;

[0012] S2: placing the substrate to be electroplated into the electroplating solution and passing current.

[0013] Wherein, the pH value of the electroplating solution in step S2 is 1 to 2.5.

[0014] Wherein, the temperature of the electroplating solution in step S2 is 25-65°C.

[0015] Wherein, the electroplating time in step S2 is 1 to 3 hours.

[0016] Wherein, the duty cycle in step S2 is 30% to 60%.

[0017] The current density in step S2 is 0.5 to 1.5 A / dm 2 .

[0018] Wherein, in the step S2, the substrate is a nickel-based high-temperature alloy.

[0019] The present invention does not limit the treatment of the substrate before electroplating and the treatment of the plated article after electroplating, and conventional pretreatment methods can be adopted, such as cleaning and polishing before plating. The selection of the electroplating electrode can also be carried out by conventional methods.

[0020] The present invention performs electroplating in an acidic environment, and by adjusting the process method, the obtained plating layer has good bonding strength and high plating layer quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The bonding force morphologies of Examples 1 to 3 (ac) and Comparative Examples 1 to 3 (df) are shown.

[0022] Figure 2 The XRD spectra of Examples 1-3 and Comparative Examples 1-3 are shown.

[0023] Figure 3 These are cross-sectional and surface morphology diagrams of Examples 1-3.

[0024] Figure 4 The cross-section and surface morphology diagrams of comparative examples 1-3 are shown. DETAILED DESCRIPTION

[0025] The technical solution of the present invention is further described below in conjunction with an embodiment. The substrate components in the embodiment meet the following conditions: the carbon content does not exceed 0.04wt.%, the chromium content does not exceed 6.96wt.%, the cobalt content does not exceed 7.41wt.%, the tungsten content does not exceed 4.98wt.%, the aluminum content does not exceed 6.30wt.%, the tantalum content does not exceed 6.47wt.%, the molybdenum content does not exceed 1.54wt.%, the rhenium content does not exceed 3.05wt.%, and the remaining elements are all nickel elements. wt.% is the percentage of the content of each component in the total mass of the nickel-based high-temperature alloy.

[0026] Example 1

[0027] The preparation process of the platinum coating in this embodiment is as follows:

[0028] (1) Pretreatment of nickel-based high-temperature alloys

[0029] The nickel-based high-temperature alloy is polished, degreased, pickled and washed in sequence.

[0030] The grinding process is to grind with 240 mesh and 400 mesh sandpaper in sequence.

[0031] The oil removal treatment was performed by ultrasonic cleaning for 15 minutes using a mixed solution of acetone and ethanol.

[0032] The pickling treatment was carried out using a 10% hydrochloric acid solution at room temperature for 2 minutes.

[0033] (2) Preparation of platinum coating

[0034] The nickel-based high-temperature alloy after the above pretreatment is subjected to platinum electroplating treatment.

[0035] In platinum electroplating, the plating solution formula is 8g / L platinum dichloride, 100g / L potassium chloride, 0.18g / L sodium glutamate, and HCl is added to adjust the pH to 1.5. The plating temperature is 45°C and the current density is 0.8A / dm 2 , plating time is 1.5H, duty cycle is 40% Example 2

[0036] The preparation process of the platinum coating in this embodiment is as follows:

[0037] (1) Pretreatment of nickel-based high-temperature alloys

[0038] The nickel-based high-temperature alloy is polished, degreased, pickled and washed in sequence.

[0039] The grinding process is to grind with 240 mesh and 400 mesh sandpaper in sequence.

[0040] The oil removal treatment was performed by ultrasonic cleaning for 15 minutes using a mixed solution of acetone and ethanol.

[0041] The pickling treatment was carried out using a 10% hydrochloric acid solution at room temperature for 2 minutes.

[0042] (2) Preparation of platinum coating

[0043] The nickel-based high-temperature alloy after the above pretreatment is subjected to platinum electroplating treatment.

[0044] In platinum electroplating, the plating solution formula is 5g / L platinum dichloride, 100g / L potassium chloride, 0.18g / L sodium glutamate, and HCl is added to adjust the pH to 1.5. The plating temperature is 45°C and the current density is 0.8A / dm 2 , plating time is 1.5H, duty cycle is 40% Example 3

[0045] The preparation process of the platinum coating in this embodiment is as follows:

[0046] (1) Pretreatment of nickel-based high-temperature alloys

[0047] The nickel-based high-temperature alloy is polished, degreased, pickled and washed in sequence.

[0048] The grinding process is to grind with 240 mesh and 400 mesh sandpaper in sequence.

[0049] The oil removal treatment was performed by ultrasonic cleaning for 15 minutes using a mixed solution of acetone and ethanol.

[0050] The pickling treatment was carried out using a 10% hydrochloric acid solution at room temperature for 2 minutes.

[0051] (2) Preparation of platinum coating

[0052] The nickel-based high-temperature alloy after the above pretreatment is subjected to platinum electroplating treatment.

[0053] In platinum electroplating, the plating solution formula is 10g / L platinum dichloride, 100g / L potassium chloride, 0.18g / L sodium glutamate, and HCl is added to adjust the pH to 1.5. The plating temperature is 45°C and the current density is 0.8A / dm 2 , the plating time is 1.5H and the duty cycle is 40%.

[0054] Comparative Example 1

[0055] The preparation process of the platinum coating in this embodiment is as follows:

[0056] (1) Pretreatment of nickel-based high-temperature alloys

[0057] The nickel-based high-temperature alloy is polished, degreased, pickled and washed in sequence.

[0058] The grinding process is to grind with 240 mesh and 400 mesh sandpaper in sequence.

[0059] The oil removal treatment was performed by ultrasonic cleaning for 15 minutes using a mixed solution of acetone and ethanol.

[0060] The pickling treatment was carried out using a 10% hydrochloric acid solution at room temperature for 2 minutes.

[0061] (2) Preparation of platinum coating

[0062] The nickel-based high-temperature alloy after the above pretreatment is subjected to platinum electroplating treatment.

[0063] In platinum electroplating, the plating solution formula is 12g / L platinum dichloride, 100g / L potassium chloride, 0.18g / L sodium glutamate, and HCl is added to adjust the pH to 1.5. The plating temperature is 45°C and the current density is 0.8A / dm 2 , the plating time is 1.5H and the duty cycle is 40%.

[0064] Comparative Example 2

[0065] The preparation process of the platinum coating in this embodiment is as follows:

[0066] (1) Pretreatment of nickel-based high-temperature alloys

[0067] The nickel-based high-temperature alloy is polished, degreased, pickled and washed in sequence.

[0068] The grinding process is to grind with 240 mesh and 400 mesh sandpaper in sequence.

[0069] The oil removal treatment was performed by ultrasonic cleaning for 15 minutes using a mixed solution of acetone and ethanol.

[0070] The pickling treatment was carried out using a 10% hydrochloric acid solution at room temperature for 2 minutes.

[0071] (2) Preparation of platinum coating

[0072] The nickel-based high-temperature alloy after the above pretreatment is subjected to platinum electroplating treatment.

[0073] In platinum electroplating, the plating solution formula is 8g / L platinum dichloride, 100g / L potassium chloride, 0.18g / L sodium glutamate, and HCl is added to adjust the pH to 1.5. The electroplating temperature is 40°C and the current density is 0.8A / dm 2 , the plating time is 2H, and the duty cycle is 40%.

[0074] Comparative Example 3

[0075] The preparation process of the platinum coating in this embodiment is as follows:

[0076] (1) Pretreatment of nickel-based high-temperature alloys

[0077] The nickel-based high-temperature alloy is polished, degreased, pickled and washed in sequence.

[0078] The grinding process is to grind with 240 mesh and 400 mesh sandpaper in sequence.

[0079] The oil removal treatment was performed by ultrasonic cleaning for 15 minutes using a mixed solution of acetone and ethanol.

[0080] The pickling treatment was carried out using a 10% hydrochloric acid solution at room temperature for 2 minutes.

[0081] (2) Preparation of platinum coating

[0082] The nickel-based high-temperature alloy after the above pretreatment is subjected to platinum electroplating treatment.

[0083] In platinum electroplating, the plating solution formula is 8g / L platinum dichloride, 100g / L potassium chloride, 0.18g / L sodium glutamate, and HCl is added to adjust the pH to 1.5. The electroplating temperature is 40°C and the current density is 0.8A / dm 2 , the plating time is 3H and the duty cycle is 40%.

[0084] The bonding strength of the coatings of Examples 1 to 3 and Comparative Examples 1 to 3 was tested by the following method: Figure 1 .

[0085] The method of scribing and gridding is used to measure the bonding strength of the coating. Specifically, the electrodeposited coating is scratched with a hard steel scribing knife with a blade of 30 degrees to form parallel lines or square grids. Observe whether the coating is lifted or peeled off. When scribing, the strength should be controlled so that the coating can be scratched through and reach the base metal with one stroke.

[0086] The internal stress of the coatings of Examples 1 to 3 and Comparative Examples 1 to 3 was tested by the following method: Figure 2 .

[0087] The samples were analyzed by X-ray diffractometer (XRD), and the half-height width of two or more peaks was measured by Gaussian distribution method (Formula 1). The square numbers were plotted to obtain the slope 16ε2 and intercept of the straight line. The microstress ε and grain size D can be calculated to determine the magnitude of the microstress of the coating after electroplating.

[0088]

[0089] Where: β is the half-height width of the diffraction peak;

[0090] θ—diffraction angle;

[0091] λ—X-ray wavelength, in nm;

[0092] D—grain size, unit: nm;

[0093] ε—micro strain

[0094] The microscopic morphology of the coatings of Examples 1 to 3 and Comparative Examples 1 to 3 was tested according to the following method:

[0095] The microstructure morphology of the sample surface is characterized by scanning electron microscopy (SEM), whether there are cracks on the coating surface is observed, and the coating thickness is determined by observing its cross section. Figure 3 , 4 As can be seen from the figure, there are fewer defects at the junction of the coating, substrate and inlay in Example 1 in the cross-sectional view.

[0096] The quality of the coatings of Examples 1 to 3 and Comparative Examples 1 to 3 was tested and the test results are as follows:

[0097]

[0098] As can be seen from the above table, in Examples 1 to 3 and Comparative Examples 1 to 3, considering the comprehensive test results of the coating, the microstrain, bonding force, surface quality and brightness of Examples 1 and 2 are better than those of other Examples. Comparative Example 1 has poor surface quality due to the high current density. Comparative Examples 2 and 3 have excessive microstrain accumulated inside the coating due to the long electroplating time, resulting in surface cracks. Since the coating thickness of Example 2 is relatively thin, the formula of Example 1 is selected. The corresponding preferred plating conditions are 8g / L platinum dichloride, 100g / L potassium chloride, 0.18g / L sodium glutamate, pH 1.5, electroplating temperature 45°C, current density 0.8A / dm 2 , the plating time is 1.5H and the duty cycle is 40%.

[0099] It should be noted and understood that various modifications and improvements can be made to the invention described in detail above without departing from the spirit and scope of the invention as claimed in the appended claims. Therefore, the scope of the claimed technical solution is not limited by any specific exemplary teaching given.

[0100] The technical principle of the present invention is described above in combination with specific embodiments. These descriptions are only for explaining the principle of the present invention and cannot be interpreted as limiting the protection scope of the present invention in any way. Based on the explanations here, those skilled in the art can think of other specific implementation methods of the present invention without creative work, and these methods will fall within the protection scope of the present invention.

Claims

1. An acid electroplating method for preparing a platinum coating on the surface of a nickel-based high-temperature alloy, characterized in that: The electroplating solution used in the acid electroplating method contains 5-10 g / L of platinum dichloride, 80 g / L of potassium chloride, and 0.1-0.2 g / L of sodium glutamate in terms of platinum.

2. The acid electroplating method for preparing a platinum coating on the surface of a nickel-based high-temperature alloy according to claim 1, characterized in that: The plating solution contains 8 g / L platinum dichloride, 100 g / L potassium chloride, and 0.18 g / L sodium glutamate, calculated as platinum.

3. An acid electroplating method for preparing a platinum coating on the surface of a nickel-based high-temperature alloy, characterized in that: The following steps are involved: S1: preparing a plating solution: dissolving various raw material components in water to form a plating solution, wherein each liter of the plating solution contains 5-10 g / L of platinum dichloride, 80 g / L of potassium chloride, and 0.1-0.2 g / L of sodium glutamate in terms of platinum; S2: placing the substrate to be electroplated into the electroplating solution and passing current to perform electroplating.

4. The acid electroplating method for preparing a platinum coating on the surface of a nickel-based high-temperature alloy according to claim 3, characterized in that: The average current density of the current in step S2 is 0.5 to 1.5 A / dm 2 .

5. The acid electroplating method for preparing a platinum coating on the surface of a nickel-based high-temperature alloy according to claim 4, characterized in that: The pH of the electroplating solution in step S2 is 1 to 2.

5.

6. The acid electroplating method for preparing a platinum coating on the surface of a nickel-based high-temperature alloy according to claim 4, characterized in that: The electroplating time in step S2 is 1 to 3 hours.

7. The acid electroplating method for preparing a platinum coating on the surface of a nickel-based high-temperature alloy according to claim 4, characterized in that: The temperature of the electroplating solution in step S2 is 25-65°C.

8. The acid electroplating method for preparing a platinum coating on the surface of a nickel-based high-temperature alloy according to claim 4, characterized in that: In step S2, the substrate is a nickel-based high-temperature alloy.

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