Method for preparing platinum layer on surface of niobium or titanium material substrate through electro-deposition in normal-temperature ionic liquid

Abstract

The invention discloses a method for preparing a platinum layer on the surface of a niobium or titanium material matrix through electro-deposition in normal-temperature ionic liquid, belongs to the technical field of surface treatment, solves the technical problem of insufficient performance of the platinum layer prepared on the surface of the niobium or titanium material matrix through electro-deposition, and comprises the following steps: S1, preparing the normal-temperature ionic liquid; s2, pretreatment of a matrix; s3, pickling and activating; s4, cleaning and soaking; s5, electro-deposition is carried out; s6, carrying out post-treatment; the steps S3-S6 are carried out in a protective atmosphere. The electro-deposition process temperature is room temperature or near room temperature; the electrochemical window is wide, and the ionic solution has adjustable physical and chemical properties through optimal combination of the anion and cation liquid, so that the oxidation-reduction potential and deposition morphology of platinum are regulated and controlled. The activated surface layer of the substrate is kept clean through ionic liquid electrodeposition, the hydrogen evolution reaction is avoided, electrodeposition is achieved under the room temperature condition to obtain the platinum layer, and meanwhile the platinum layer is good in interface bonding force, free of porosity and compact in crystallization.

Description

Technical Field

[0001] The invention belongs to the technical field of surface treatment, and particularly relates to a method for preparing a platinum layer by electro-deposition on the surface of a niobium or titanium substrate in a room-temperature ionic liquid. Background Art

[0002] Niobium- and titanium-based platinum materials combine the high strength and corrosion resistance of niobium (Nb), titanium (Ti), and their alloys with the excellent conductivity and chemical stability of the platinum layer, demonstrating significant application value in a wide range of high-tech fields. Their combined advantages of a "high-strength matrix + functional surface layer" make them irreplaceable in applications such as high-temperature, high-corrosion, and high-precision signal transmission. With the rapid development of intelligent sensing and control, hydrogen energy, energy storage, and medical technologies, their application prospects will further expand, particularly in reducing platinum usage and improving adaptability to extreme environments.

[0003] Niobium-based platinum and titanium-based platinum materials can be used as electrodes in extreme environments. When titanium or niobium and their alloys are used independently, titanium, while lightweight, has poor electrical conductivity. While niobium is a good conductor of electricity, it is susceptible to surface passivation in environments such as strong acids and high-temperature molten salts, resulting in a decrease in conductivity. Therefore, combining titanium and niobium with a platinum (Pt) layer on their surfaces can significantly improve their corrosion resistance and electrochemical activity.

[0004] After years of development, the electrodeposition of platinum in aqueous solution systems with water as solvent has made great progress. Acidic platinum, alkaline platinum and neutral platinum are all used in the production field. However, there are some defects in general:

[0005] 1. When platinum layer is electrodeposited in aqueous solution, there is a side reaction of hydrogen evolution. Hydrogen atoms penetrate into the metal. Hydrogen is present in the gaps between the lattice and can also be focused on defects such as dislocations, grain boundaries, and holes, forming local high-concentration enrichment areas, causing hydrogen embrittlement of the metal material, resulting in brittleness of the metal substrate and metal layer, causing fracture of parts, shedding of the deposited metal layer, and shortening the service life.

[0006] 2. The platinum layer electrodeposited by aqueous solution has high porosity, insufficient interfacial bonding strength, a narrow electrochemical window of aqueous solution, and uneven current distribution on workpieces with complex structures, which leads to insufficient uniform electrodeposition capability and limits its application in precision scenarios.

[0007] After years of development, the electroplating of platinum in an organic solution system with liquid organic matter as solvent came into being, but its poor conductivity, flammability and volatility, and relatively narrow operating temperature range limit its development and application.

[0008] In addition, platinum is electro-deposited in a high-temperature molten salt system using high-temperature molten salt as a solvent. The process has a wide electrochemical window, but the operation process is complicated, the control process is difficult, and the energy consumption is high. The process temperature is >300°C, or even >500°C. The substrate is prone to thermal deformation and the internal stress of the platinum layer is large. Summary of the Invention

[0009] In order to solve the technical problem of insufficient performance of platinum layers prepared by electrodeposition on the surface of niobium or titanium substrates in the prior art, the present invention provides a method for preparing a platinum layer by electrodeposition on the surface of a niobium or titanium substrate in a room-temperature ionic liquid. The method adopts a room-temperature ionic liquid system and, with the assistance of inert gas protection, utilizes the synergistic effect of a dual-pulse power supply and a composite additive to deposit a platinum layer on the surface of a niobium or titanium substrate. The prepared platinum layer has fine crystals, no porosity, strong bonding with the substrate, and a long service life.

[0010] The present invention is achieved through the following technical solution: a method for preparing a platinum layer by electrodeposition on the surface of a niobium or titanium substrate in a room temperature ionic liquid, comprising the following steps:

[0011] S1. Prepare room temperature ionic liquid:

[0012] S1-1. Prepare a base solvent: mix hexafluorophosphate solution and tetramethylammonium tetrafluoroborate solution at a molar ratio of (5-9): (5-1) at room temperature to prepare a base solvent; select imidazole and quaternary ammonium salt ionic liquids for compounding, wherein the cation preferably has a shorter carbon chain structure, and among various anions (such as halogen ions, hexafluorophosphate, tetrafluoroborate, etc.), hexafluorophosphate (BMIM)PF6 is preferred; in order to reduce the viscosity, improve the conductivity and cyclic stability of the ionic liquid, tetramethylammonium tetrafluoroborate (N 1111 )BF4;

[0013] S1-2, dissolving a platinum salt having a concentration of 0.05 mol / L to 0.20 mol / L into the base solvent prepared in step S1-1 to prepare a platinum-based room-temperature ion base solution;

[0014] S1-3. Add additives to the platinum-based room-temperature ionic basic solution prepared in step S1-2, and fully dissolve them to prepare a room-temperature ionic liquid for use; the composition and ratio of the additives are as follows: thiourea (CH4N2S): 0.005g / L-0.01g / L; citric acid (H3C6H5O7): 0.03g / L-0.1g / L; potassium citrate (K3C6H5O7): 0.03g / L-0.1g / L; dipotassium hydrogen phosphate (K2HPO4): 0.01g / L-0.05g / L; ascorbic acid (C6H8O6): 1g / L-3g / L; 1,2-propylene glycol (C3H8O2): 0.005g / L-0.01g / L;

[0015] S2. Substrate pretreatment: The substrate is made of niobium or titanium. The substrate is immersed in a phosphorus-free environmentally friendly chemical degreasing agent for ultrasonic treatment. The ultrasonic frequency is 28KHz to 40KHz, the degreasing temperature is 50℃-80℃, and the degreasing time is 1-5 minutes.

[0016] The following steps S3 to S6 are all carried out in a protective atmosphere with a protective gas flow rate of 0.5 L / min-1 L / min. The protective gas covers the surface of the ionic liquid and the dissolved oxygen content of the ionic liquid is maintained at ≤0.1 ppm.

[0017] S3, pickling activation: the substrate after the pre-treatment in step S2 is washed with hot water and then immersed in a pickling activator, the pickling activation temperature is 10°C-60°C, and the pickling activation time is 0.5min-5min; the composition and proportion of the pickling activator are as follows: hydrofluoric acid (HF): 30g / L-100g / L; nitric acid (HNO3): 0-300g / L, sulfuric acid (H2SO4): 150g / L-300g / L; aminosulfonic acid (H2NSO3H): 0-10g / L, and the rest is water;

[0018] S4, cleaning and soaking: immersing the substrate activated by pickling in step S3 in a soaking solution for 10s-30s; the composition and volume ratio of the soaking solution are: ethanol (C2H5OH): 10%-90%; n-butanol (C4H9OH): 10%-90%, and the sum of the proportions of each component is 100%; using protective gas to blow dry the soaked substrate and place it in an ultrasonic electrodeposition tank;

[0019] S5. Electrodeposition: Add the room temperature ionic liquid prepared in step S1-3 into an ultrasonic electrodeposition tank and immerse the substrate, using the substrate as a cathode electrode; the anode electrode is made of pure platinum, niobium-based platinum, or titanium-based platinum, and is in the shape of a plate or mesh. The effective deposition area ratio of the cathode electrode to the anode electrode is 1:(1-2);

[0020] Start the dual pulse power supply, the frequency of the dual pulse power supply is 40Hz-120Hz, among which, the forward pulse: the current density is 0.5-30A / dm 2 , pulse width is 5-20ms, duty cycle is 10%-50%; reverse pulse: current density is 0.25-30A / dm 2 , a pulse width of 5-20ms, and a duty cycle of 5%-20%; setting the ultrasonic frequency of the ultrasonic electrodeposition tank to 28KHz-40KHz and the electrodeposition temperature to 10°C-80°C to electrodeposit a platinum layer on the substrate surface; controlling the thickness of the electrodeposited platinum layer by adjusting the positive and reverse pulse current density, pulse width and duty cycle of the pulse power supply in the process, as well as the temperature, solution concentration and electrodeposition time in the electrodeposition process;

[0021] S6. Post-treatment: Take out the substrate on which the platinum layer was electrodeposited in step S5, and immerse it in an immersion solution having the following composition and volume ratio: ethanol (C2H5OH): 10%-90%; n-butanol (C4H9OH): 10%-90%, and the sum of the proportions of each component is 100%; the immersion time is 10s-30s, and after immersion, the substrate is blown dry with protective gas, and finally dried in an oven at a temperature of 80°C for 1-2 hours to obtain a niobium or titanium material with an electrodeposited platinum layer on the surface.

[0022] Furthermore, in step S1-2, the platinum salt is platinum tetrachloride (PtCl4), chloroplatinic acid (H2PtCl4), dinitrodiammineplatinum (Pt(NH3)2(NO3)2) or potassium tetranitroplatinate (K2Pt(N02)4).

[0023] Furthermore, in step S2, the composition and proportion of the phosphorus-free environmentally friendly chemical degreasing agent are as follows: sodium hydroxide (NaOH): 10wt%-15wt%; sodium carbonate (Na2CO3): 15wt%-20wt%; sodium silicate (Na2SiO3): 10wt%-15wt%; sodium EDTA-2 (C 10 H 14 N2Na2O8·2H2O): 1wt%-3wt%; JFC penetrant: 1wt%-5wt%; betaine: 0.2wt%-1.0wt%; the remainder is water.

[0024] Furthermore, the protective atmosphere is at least one of carbon dioxide, nitrogen or argon.

[0025] The beneficial effects of the present invention are: the electrodeposition process temperature is at or near room temperature; the electrochemical window is wide, and through the optimized combination of anionic and cationic liquids, the ionic solution has adjustable physicochemical properties, thereby regulating the redox potential and deposition morphology of platinum. This ionic liquid process for electrodepositing platinum layers combines the advantages of aqueous solutions, high-temperature molten salts, and organic solvents. Ionic liquid electrodeposition maintains a clean surface layer of the activated substrate, eliminates hydrogen evolution reactions, and allows electrodeposition of the platinum layer at room temperature. Simultaneously, it achieves the excellent bonding strength, porosity, and dense crystallization of the platinum layer previously only possible in high-temperature molten salts. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a flowchart of the preparation method of the present invention;

[0027] Figure 2 This is an optical microscope photograph of the niobium-based material with a surface electrodeposited platinum layer prepared in Example 1 (magnification 200 times);

[0028] Figure 3 This is an SEM photo of the niobium-based material with a surface electrodeposited platinum layer prepared in Example 1;

[0029] Figure 4 This is an EDS graph of the niobium-based material with a surface electrodeposited platinum layer prepared in Example 1;

[0030] Figure 5 This is an optical microscope photograph of the titanium-based material with a surface electrodeposited platinum layer prepared in Example 2 (magnification 200 times);

[0031] Figure 6 This is an SEM photo of the titanium-based material with the surface electrodeposited platinum layer prepared in Example 2;

[0032] Figure 7 This is the EDS curve of the titanium-based material with the surface electrodeposited platinum layer prepared in Example 2. DETAILED DESCRIPTION

[0033] The present invention will be described in further detail below with reference to the accompanying drawings and examples.

[0034] Example 1

[0035] like Figure 1 As shown, this embodiment 1 provides a method for preparing a platinum layer by electrodeposition on the surface of a niobium substrate in a room temperature ionic liquid, wherein the niobium substrate is a niobium plate with a purity of 99.5% and dimensions of 100 mm in length, 50 mm in width, and 1.5 mm in thickness. The preparation method comprises the following steps:

[0036] S1. Prepare room temperature ionic liquid:

[0037] S1-1. Prepare a base solvent: uniformly mix 1-methyl-3-butylimidazole hexafluorophosphate solution and tetramethylammonium tetrafluoroborate solution at a molar ratio of 8:2 at room temperature to prepare a base solvent;

[0038] S1-2, dissolving H2PtCl4 at a concentration of 0.05 mol / L into the base solvent prepared in step S1-1 to prepare a platinum-based room-temperature ion base solution;

[0039] S1-3. Add additives to the platinum-based room-temperature ionic solution prepared in step S1-2, and fully dissolve to prepare a room-temperature ionic liquid for standby use; the composition and ratio of the additives are: K2HPO4: 0.02 g / L; C6H8O6: 2 g / L; CH4N2S: 0.005 g / L; C3H8O2: 0.005 g / L;

[0040] S2. Substrate pretreatment: Immerse the substrate in a phosphorus-free environmentally friendly chemical degreasing agent for ultrasonic treatment. The ultrasonic frequency is 28KHz, the degreasing temperature is 50℃-80℃, and the degreasing time is 3 minutes. The composition and ratio of the phosphorus-free environmentally friendly chemical degreasing agent are as follows: NaOH: 11wt%; Na2CO3: 15wt%; Na2SiO3: 12wt%; C 10 H 14 N2Na2O8·2H2O: 2wt%; JFC penetrant: 3wt%; betaine: 0.5wt%, the rest is water;

[0041] The following steps S3 to S6 are all carried out in a nitrogen protective atmosphere with a protective gas flow rate of 0.5 L / min. The protective gas covers the liquid surface of the ionic liquid and the dissolved oxygen content of the ionic liquid is maintained at ≤0.1 ppm;

[0042] S3, pickling activation: the substrate after the pre-treatment in step S2 is washed with hot water and then immersed in a pickling activator. The pickling activation temperature is 15±2° C. and the pickling activation time is 3 minutes. The composition and proportion of the pickling activator are as follows: HF: 40 g / L; HNO3: 150 g / L; H2SO4: 300 g / L; H2NSO3H: 5 g / L, and the remainder is water.

[0043] S4. Cleaning and soaking: Immerse the substrate activated by pickling in step S3 in a soaking solution for 10 seconds; the composition and volume ratio of the soaking solution are: C2H5OH: 20%; C4H9OH: 80%; blow dry the soaked substrate with protective gas and place it in an ultrasonic electrodeposition tank;

[0044] S5, electrodeposition: Add the room temperature ionic liquid prepared in step S1-3 into the ultrasonic electrodeposition tank and immerse the substrate, using the substrate as the cathode electrode; the anode is a titanium platinum mesh with dimensions of 110 mm in length × 60 mm in width × 2 mm in thickness;

[0045] Start the dual pulse power supply, the frequency of the dual pulse power supply is 50Hz, among which, the forward pulse: the current density is 10A / dm 2 , pulse width is 20ms, duty cycle is 20%; reverse pulse: current density is 5A / dm 2 , the pulse width is 5ms, the duty cycle is 10%; the ultrasonic frequency of the ultrasonic electrodeposition tank is set to 40KHz, the electrodeposition temperature is 25°C, the electrodeposition time is 10min, and a platinum layer is electrodeposited on the surface of the niobium substrate;

[0046] S6. Post-treatment: The substrate on which the platinum layer was electrodeposited in step S5 was taken out and immersed in an immersion solution having the following composition and volume ratio: C2H5OH: 90%; C4H9OH: 10%; the immersion time was 10s-30s, and after immersion, the substrate was blown dry with protective gas and finally dried in an environment at 80°C for 1 hour to obtain a niobium material with a surface electrodeposited platinum layer. The microstructure of the niobium material with a surface electrodeposited platinum layer prepared in Example 1 is shown in FIG. Figure 2 shown.

[0047] According to the thickness gauge of GB / T 16921-2005 Metal coating - Measurement of coating thickness by X-ray spectrometry, the thickness of the platinum layer is 3±0.2μm.

[0048] According to GB / T5270-2005 Review of Test Method for Adhesion Strength of Electrodeposited and Chemically Deposited Metal Coatings on Metal Substrates, a sharp-edged hard steel scratcher with a scratch angle of 30° should be used, with a scratch length of 1 mm and a 3 cm square. 2 Internal observation results showed that the platinum layer did not fall off.

[0049] According to GB / T19351-2003 Determination of the porosity of metal substrate covering layers: nitric acid vapor test, nitric acid 69±2%, temperature 23±3℃, humidity RH40-55%, after 60 minutes, take out and expose, there are no bubbles on the surface of the platinum layer, then put the test piece in an oven at 130℃ and dry it for 60 minutes. Use 10 times magnification to magnify the surface, there are no corrosion products on the whole, and it is determined to be no porosity.

[0050] The SEM image of the niobium material with surface electrodeposited platinum layer prepared in Example 1 ( Figure 2 The cross section shows that the platinum layer is dense and has no pores; the EDS image of the niobium material with surface electrodeposited platinum layer prepared in Example 1 (as shown) Figure 3 As shown in the figure, it can be seen that the platinum layer is extremely thin, so in addition to Pt, there are also some Nb matrix components in the EDS.

[0051] Example 2

[0052] like Figure 1 As shown, this embodiment 2 provides a method for preparing a platinum layer by electrodeposition on the surface of a titanium substrate in an ionic liquid at room temperature, wherein the titanium substrate is a titanium mesh with a purity of 99.5%, the dimensions of which are 100 mm in length × 50 mm in width × 2 mm in thickness, and the mesh size is 10 mm in length × 5 mm in width. The preparation method comprises the following steps:

[0053] S1. Prepare room temperature ionic liquid:

[0054] S1-1. Prepare a base solvent: uniformly mix 1-methyl-3-butylimidazole hexafluorophosphate solution and tetramethylammonium tetrafluoroborate solution at a molar ratio of 7:3 at room temperature to prepare a base solvent;

[0055] S1-2, dissolving PtCl4 at a concentration of 0.08 mol / L into the base solvent prepared in step S1-1 to prepare a platinum-based room-temperature ion base solution;

[0056] S1-3. Add additives to the platinum-based room-temperature ionic solution prepared in step S1-2, and fully dissolve to prepare a room-temperature ionic liquid for standby use; the composition and ratio of the additives are: K2HPO4: 0.05 g / L; C6H8O5: 5 g / L; C3H8O2: 0.010 g / L;

[0057] S2. Substrate pretreatment: Immerse the substrate in a phosphorus-free environmentally friendly chemical degreasing agent for ultrasonic treatment. The ultrasonic frequency is 28KHz, the degreasing temperature is 55°C, and the degreasing time is 5 minutes. The composition and proportion of the phosphorus-free environmentally friendly chemical degreasing agent are as follows: NaOH: 15wt%; Na2CO3: 12wt%; Na2SiO3: 10wt%; C 10 H 14 N2Na2O8·2H2O: 1wt%; JFC penetrant: 2wt%; betaine: 0.5wt%, the rest is water;

[0058] The following steps S3 to S6 are all carried out in a nitrogen protective atmosphere with a protective gas flow rate of 0.5 L / min. The protective gas covers the liquid surface of the ionic liquid and the dissolved oxygen content of the ionic liquid is maintained at ≤0.1 ppm;

[0059] S3, pickling activation: the substrate after the pre-treatment in step S2 is washed with hot water and then immersed in a pickling activator. The pickling activation temperature is 20-25°C and the pickling activation time is 5 minutes. The composition and proportion of the pickling activator are as follows: HF: 50g / L; H2SO4: 250g / L; the remainder is water;

[0060] S4, cleaning and soaking: immersing the substrate activated by pickling in step S3 in a soaking solution for 20 seconds; the composition and volume ratio of the soaking solution are: C2H5OH: 90%; C4H9OH: 10%; using protective gas to blow dry the soaked substrate and place it in an ultrasonic electrodeposition tank;

[0061] S5, electrodeposition: Add the room temperature ionic liquid prepared in step S1-3 into the ultrasonic electrodeposition tank and immerse the substrate, using the substrate as the cathode electrode; the anode uses a niobium-based platinum mesh with dimensions of 100 mm in length × 50 mm in width × 1.5 mm in thickness;

[0062] Start the dual pulse power supply, the frequency of the dual pulse power supply is 40Hz, among which, the forward pulse: the current density is 30A / dm 2 , pulse width is 5ms, duty cycle is 15%; reverse pulse: current density is 15A / dm 2, the pulse width is 5ms, the duty cycle is 30%; the ultrasonic frequency of the ultrasonic electrodeposition tank is set to 40KHz, the electrodeposition temperature is 20°C, the electrodeposition time is 5min, and a platinum layer is electrodeposited on the substrate surface;

[0063] S6, post-processing: This step is the same as the post-processing step S6 of Example 1, and will not be described in detail here. The titanium material with a surface electrodeposited platinum layer is obtained. The microstructure of the titanium material with a surface electrodeposited platinum layer prepared in Example 2 is as follows: Figure 5 shown.

[0064] According to the thickness gauge of GB / T 16921-2005 Metal coating - Measurement of coating thickness by X-ray spectrometry, the thickness of the platinum layer is 5±0.2μm.

[0065] According to GB / T5270-2005 Review of Test Method for Adhesion Strength of Electrodeposited and Chemically Deposited Metal Coatings on Metal Substrates, a sharp-edged hard steel scratcher with a scratch angle of 30° should be used, with a scratch length of 1 mm and a 3 cm square. 2 Internal observation results showed that the platinum layer did not fall off.

[0066] According to GB / T19351-2003 Determination of the porosity of metal substrate covering layers: nitric acid vapor test, nitric acid 69±2%, temperature 23±3℃, humidity RH40-55%, after 75 minutes, take out and expose, there are no bubbles on the surface of the platinum layer, then put the test piece in an oven at 130℃ and dry it for 60 minutes. Use 10 times magnification to magnify the surface. There are no corrosion products on the whole, which is determined to be no porosity.

[0067] The SEM image of the titanium material with surface electroplated platinum layer prepared in Example 2 ( Figure 6 The cross section shows that the platinum layer is dense and has no pores; the EDS image of the titanium material with surface electrodeposited platinum layer prepared in Example 2 (as shown) Figure 7 As shown in the figure, it can be seen that due to the extremely thin platinum layer, in addition to Pt, there are also some Ti matrix components in the EDS.

[0068] Example 3

[0069] like Figure 1 As shown, this embodiment 3 provides a method for preparing a platinum layer by electrodeposition on the surface of a niobium substrate in an ionic liquid at room temperature, wherein the niobium substrate is a niobium mesh with a purity of 99.5%, the dimensions of which are 150 mm in length × 100 mm in width × 1.5 mm in thickness, and the mesh dimensions are 12 mm in length × 6 mm in width. The preparation method comprises the following steps:

[0070] S1. Prepare room temperature ionic liquid:

[0071] S1-1. Prepare a base solvent: uniformly mix 1-methyl-3-butylimidazole hexafluorophosphate solution and tetramethylammonium tetrafluoroborate solution at a molar ratio of 9:1 at room temperature to prepare a base solvent;

[0072] S1-2, dissolving K2Pt(N02)4 at a concentration of 0.2 mol / L into the base solvent prepared in step S1-1 to prepare a platinum-based room-temperature ion base solution;

[0073] S1-3, adding additives to the platinum-based room-temperature ionic basic solution prepared in step S1-2, and fully dissolving to prepare a room-temperature ionic liquid for standby use; the composition and ratio of the additives are: C6H8O6: 2.5g / L; H3C5H4O7: 0.05g / L;

[0074] S2. Substrate pretreatment: Immerse the substrate in a phosphorus-free environmentally friendly chemical degreasing agent for ultrasonic treatment. The ultrasonic frequency is 40KHz, the degreasing temperature is 50℃-80℃, and the degreasing time is 3 minutes. The composition and ratio of the phosphorus-free environmentally friendly chemical degreasing agent are as follows: NaOH: 11wt%; Na2CO3: 15wt%; Na2SiO3: 12wt%; C 10 H 14 N2Na2O8·2H2O: 2wt%; JFC penetrant: 3wt%; betaine: 0.5wt%, the rest is water;

[0075] The following steps S3 to S6 are all carried out in a nitrogen protective atmosphere with a protective gas flow rate of 0.5 L / min. The protective gas covers the liquid surface of the ionic liquid and the dissolved oxygen content of the ionic liquid is maintained at ≤0.1 ppm;

[0076] S3, pickling activation: the substrate after the pre-treatment in step S2 is washed with hot water and then immersed in a pickling activator. The pickling activation temperature is room temperature and the pickling activation time is 10 minutes. The composition and proportion of the pickling activator are as follows: HF: 40g / L; HNO3: 150g / L; H2SO4: 200g / L, and the remainder is water;

[0077] S4. Cleaning and soaking: Immerse the substrate activated by pickling in step S3 in a soaking solution for 10 seconds; the composition and volume ratio of the soaking solution are: C2H5OH: 20%; C4H9OH: 80%; blow dry the soaked substrate with protective gas and place it in an ultrasonic electrodeposition tank;

[0078] S5, electrodeposition: Add the room temperature ionic liquid prepared in step S1-3 into the ultrasonic electrodeposition tank and immerse the substrate, using the substrate as the cathode electrode; the anode is a titanium platinum mesh with dimensions of 200 mm in length × 150 mm in width × 1 mm in thickness;

[0079] Start the dual pulse power supply, the frequency of the dual pulse power supply is 50Hz, among which, the forward pulse: the current density is 20A / dm 2 , pulse width is 20ms, duty cycle is 30%; reverse pulse: current density is 10A / dm 2 , the pulse width is 5ms, the duty cycle is 15%; the ultrasonic frequency of the ultrasonic electrodeposition tank is set to 40KHz, the electrodeposition temperature is 40℃, the electrodeposition time is 10min, and a platinum layer is electrodeposited on the substrate surface;

[0080] S6. Post-treatment: The substrate with the platinum layer electrodeposited in step S5 is taken out and immersed in an immersion solution having the following composition and volume ratio: C2H5OH: 80%; C4H9OH: 20%; the immersion time is 20 seconds, and after immersion, it is blown dry with protective gas and finally dried in an environment at 60° C. for 2 hours to obtain a niobium material with a surface electrodeposited platinum layer.

[0081] According to the thickness gauge of GB / T 16921-2005 Metal coating - Measurement of coating thickness - X-ray spectrometry, the thickness of the platinum layer is 8±0.5μm.

[0082] According to GB / T5270-2005 Review of Test Method for Adhesion Strength of Electrodeposited and Chemically Deposited Metal Coatings on Metal Substrates, a sharp-edged hard steel scratcher with a scratch angle of 30° should be used, with a scratch length of 1 mm and a 3 cm square. 2 Internal observation results showed that the platinum layer did not fall off.

[0083] According to GB / T19351-2003 Determination of the porosity of metal substrate covering layers: nitric acid vapor test, nitric acid 69±2%, temperature 23±3℃, humidity RH40-55%, after 75 minutes, take out and expose, there are no bubbles on the surface of the platinum layer, then put the test piece in an oven at 130℃ and dry it for 60 minutes. Use 10 times magnification to magnify the surface. There are no corrosion products on the whole, which is determined to be no porosity.

[0084] Example 4

[0085] like Figure 1 As shown, this embodiment 4 provides a method for preparing a platinum layer by electrodeposition on the surface of a titanium substrate in an ionic liquid at room temperature, wherein the titanium substrate is a titanium mesh with a purity of 99.5% and a size of 150 mm in length × 150 mm in width × 1 mm in thickness. The preparation method comprises the following steps:

[0086] S1. Prepare room temperature ionic liquid:

[0087] S1-1. Prepare a base solvent: uniformly mix 1-methyl-3-butylimidazole hexafluorophosphate solution and tetramethylammonium tetrafluoroborate solution at a molar ratio of 6:4 at room temperature to prepare a base solvent;

[0088] S1-2, dissolving Pt(NH3)2(NO3)2 with a concentration of 0.015 mol / L into the basic solvent prepared in step S1-1 to prepare a platinum-based room temperature ion basic solution;

[0089] S1-3. Add additives to the platinum-based room-temperature ionic solution prepared in step S1-2, and fully dissolve to prepare a room-temperature ionic liquid for use; the composition and ratio of the additives are: H3C6H5O7: 0.1 g / L; K2HPO4: 0.02 g / L; ascorbic acid: 1.5 g / L; C6H8O6: 0.01 g / L; C3H8O2: 0.01 g / L;

[0090] S2, substrate pretreatment: This step is the same as the substrate pretreatment in step S2 of Example 2, and will not be described in detail here;

[0091] The following steps S3 to S6 are all carried out in an argon protective atmosphere with a protective gas flow rate of 0.5 L / min. The protective gas covers the liquid surface of the ionic liquid and the dissolved oxygen content of the ionic liquid is maintained at ≤0.1 ppm;

[0092] In this embodiment 4, step S3 of pickling and activation and step S4 of cleaning and soaking are the same as those in embodiment 2, and are not described in detail here;

[0093] S5, electrodeposition: adding the room temperature ionic liquid prepared in step S1-3 into an ultrasonic electrodeposition tank and immersing the substrate, with the substrate serving as the cathode electrode; using a niobium-based platinum mesh as the anode, with dimensions of 200 mm in length, 200 mm in width, and 1.5 mm in thickness;

[0094] Start the dual pulse power supply, the frequency of the dual pulse power supply is 100Hz, among which, the forward pulse: the current density is 0.5A / dm 2 , pulse width is 5ms, duty cycle is 25%; reverse pulse: current density is 5A / dm 2 , the pulse width is 3ms, the duty cycle is 5%; the ultrasonic frequency of the ultrasonic electrodeposition tank is set to 40KHz, the electrodeposition temperature is 50℃, the electrodeposition time is 2h, and a platinum layer is electrodeposited on the substrate surface;

[0095] S6. Post-processing: This step is the same as the post-processing step S6 in Example 3 and will not be described in detail here. A titanium material with a surface electrodeposited platinum layer is obtained.

[0096] According to the thickness gauge of GB / T 16921-2005 Metal coating - Measurement of coating thickness by X-ray spectrometry, the thickness of the platinum layer is 1.5±0.5μm.

[0097] According to GB / T19351-2003 Determination of the porosity of metal substrate covering layers: nitric acid vapor test, nitric acid 69±2%, temperature 23±3℃, humidity RH40-55%, after 75 minutes, take out and expose, there are no bubbles on the surface of the platinum layer, then put the test piece in an oven at 130℃ and dry it for 60 minutes. Use 10 times magnification to magnify the surface. There are no corrosion products on the whole, which is determined to be no porosity.

[0098] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for preparing a platinum layer by electrodeposition on the surface of a niobium or titanium substrate in an ionic liquid at room temperature, characterized in that: The following steps are involved: S1. Prepare room temperature ionic liquid: S1-1. Prepare a base solvent: uniformly mix the hexafluorophosphate solution and the tetramethylammonium tetrafluoroborate solution in a molar ratio of (5-9):(5-1) at room temperature to prepare a base solvent; S1-2, dissolving a platinum salt having a concentration of 0.05 mol / L to 0.20 mol / L into the base solvent prepared in step S1-1 to prepare a platinum-based room-temperature ion base solution; S1-3. Add additives to the platinum-based room-temperature ionic basic solution prepared in step S1-2, and fully dissolve to prepare a room-temperature ionic liquid for standby use; the composition and ratio of the additives are: thiourea: 0.005 g / L-0.01 g / L; Citric acid: 0.03g / L-0.1g / L; Potassium citrate: 0.03g / L-0.1g / L; Dipotassium hydrogen phosphate: 0.01g / L-0.05g / L; Ascorbic acid: 1g / L-3g / L; 1,2-propylene glycol: 0.005g / L-0.01g / L; S2. Substrate pretreatment: The substrate is made of niobium or titanium. The substrate is immersed in a phosphorus-free environmentally friendly chemical degreasing agent for ultrasonic treatment. The ultrasonic frequency is 28KHz~40KHz, the degreasing temperature is 50℃-80℃, and the degreasing time is 1-5 minutes. The following steps S3 to S6 are all carried out in a protective atmosphere with a protective gas flow rate of 0.5 L / min-1 L / min. The protective gas covers the surface of the ionic liquid and the dissolved oxygen content of the ionic liquid is maintained at ≤0.1 ppm. S3, pickling activation: the substrate after the pre-treatment in step S2 is washed with hot water and then immersed in a pickling activator. The pickling activation temperature is 10°C-60°C and the pickling activation time is 0.5min-5min. The composition and proportion of the pickling activator are as follows: hydrofluoric acid: 30g / L-100g / L; Nitric acid: 0-300g / L, sulfuric acid: 150g / L-300g / L; sulfamic acid: 0-10g / L, the rest is water; S4, cleaning and soaking: immersing the substrate activated by pickling in step S3 in a soaking solution for 10s-30s; the composition and volume ratio of the soaking solution are: ethanol: 10%-90%; n-butanol: 10%-90%, and the sum of the proportions of each component is 100%; using protective gas to blow dry the soaked substrate and place it in an ultrasonic electrodeposition tank; S5. Electrodeposition: Add the room temperature ionic liquid prepared in step S1-3 into an ultrasonic electrodeposition tank and immerse the substrate, using the substrate as a cathode electrode; the anode electrode is made of pure platinum, niobium-based platinum, or titanium-based platinum, and is in the shape of a plate or mesh. The effective deposition area ratio of the cathode electrode to the anode electrode is 1:(1-2); A dual-pulse power supply is started, the frequency of which is 40 Hz-120 Hz, wherein the forward pulse has a current density of 0.5-30 A / dm², a pulse width of 5-20 ms, and a duty cycle of 25%-50%; the reverse pulse has a current density of 0.25-30 A / dm², a pulse width of 3-8 ms, and a duty cycle of 5%-20%; the ultrasonic frequency of the ultrasonic electrodeposition tank is set to 28 kHz-40 kHz, the electrodeposition temperature is set to 10°C-80°C, and a platinum layer is electrodeposited on the surface of the substrate; S6. Post-processing: Take out the substrate with the platinum layer electrodeposited in step S5, and immerse it in an immersion solution. The composition and volume ratio of the immersion solution are: ethanol: 10%-90%; n-butanol: 10%-90%, and the sum of the proportions of each component is 100%; the immersion time is 10s-30s, and after immersion, it is blown dry with protective gas, and finally dried in an environment at a temperature of 80°C for 1-2 hours to obtain a niobium or titanium material with a surface electrodeposited platinum layer.

2. The method for preparing a platinum layer by electrodeposition on the surface of a niobium or titanium substrate in a room temperature ionic liquid according to claim 1, characterized in that: In step S1-2, the platinum salt is platinum tetrachloride, chloroplatinic acid, dinitrodiammineplatinum or potassium tetranitroplatinate.

3. The method for preparing a platinum layer by electrodeposition on the surface of a niobium or titanium substrate in a room temperature ionic liquid according to claim 1, characterized in that: In step S2, the composition and ratio of the phosphorus-free environmentally friendly chemical degreasing agent are as follows: sodium hydroxide: 10wt%-15wt%; sodium carbonate: 15wt%-20wt%; Sodium silicate: 10wt%-15wt%; EDTA-2 sodium: 1wt%-3wt%; JFC penetrant: 1wt%-5wt%; Betaine: 0.2wt%-1.0wt%, the rest is water.

4. The method for preparing a platinum layer by electrodeposition on the surface of a niobium or titanium substrate in a room temperature ionic liquid according to claim 1, characterized in that: The protective atmosphere is at least one of carbon dioxide, nitrogen or argon.

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