Titanium felt surface pickling process

Abstract

The invention relates to the technical field of metal surface treatment, and discloses a titanium felt surface pickling process which is characterized by comprising the following steps: step 1, pretreating a titanium felt; step 2, preparing a pickling solution, wherein the pickling solution comprises 3-5% (by volume) of hydrofluoric acid, 15-20% (by volume) of nitric acid, 0.5-1% (by mass) of a corrosion inhibitor and the balance of deionized water; 3, acid pickling is conducted, specifically, the pretreated titanium felt is hung in an acid pickling tank through a clamp, it is ensured that the titanium felt is completely immersed in an acid pickling solution, a stirring device is started, the speed is controlled to be 100-200 r / min, the temperature is controlled to be 30-40 DEG C, and acid pickling is conducted for 5-15 min; and step 4, cleaning. The titanium felt surface pickling process has the advantages of being efficient in cleaning, low in damage, environmentally friendly and safe.

Description

Technical Field

[0001] The present application relates to the technical field of metal surface treatment, and more specifically, to a titanium felt surface pickling process. Background Art

[0002] Hydrogen energy, as a new generation of renewable green energy, has garnered widespread attention, and hydrogen production technology is crucial for its development. Proton exchange membrane water electrolysis (PEMWE) has attracted widespread attention in the hydrogen energy field due to its advantages, including high hydrogen yield, fast start-stop, and high energy efficiency. Under the acidic, oxygen-rich, and highly polarized operating environment of the PEMWE anode, a high-performance platinum-coated gas diffusion layer (platinum-coated titanium felt) is designed to enhance the corrosion resistance, conductivity, hydrophilicity, and stability of the titanium-based porous transport layer, providing insights for promoting the industrial application of water electrolysis hydrogen production technology.

[0003] Due to its unique physical and chemical properties, such as high specific surface area and excellent corrosion resistance, titanium felt is widely used in numerous fields, including chemical catalysis, battery electrode materials, and filtration separation. However, during the production, processing, and storage of titanium felt, its surface inevitably forms oxide scale, becomes contaminated with oil, and absorbs other impurities. These surface contaminants not only affect the titanium felt's appearance but, more importantly, reduce its surface activity, thereby affecting its performance in subsequent applications.

[0004] Traditional titanium felt surface treatment methods, such as mechanical polishing and single acid cleaning, have numerous drawbacks. Mechanical polishing can easily damage the titanium felt's fiber structure, leading to a decrease in its mechanical properties. Single acid cleaning struggles to effectively remove scale, oil, and impurities simultaneously, and can easily lead to excessive corrosion or incomplete cleaning. Therefore, developing an efficient, safe, and environmentally friendly titanium felt surface pickling process is of great practical significance. Summary of the Invention

[0005] The purpose of the present invention is to provide a titanium felt surface pickling process, which can effectively remove oxide scale, oil stains and impurities on the titanium felt surface, improve the surface quality and activity of the titanium felt, and at the same time minimize damage to the titanium felt substrate to achieve the purpose of surface cleaning.

[0006] In order to achieve the above-mentioned invention objectives, this application adopts the following technical solutions: The present application provides a titanium felt surface pickling process, comprising the following steps: Step 1, titanium felt pretreatment; Step 2, preparing a pickling solution, wherein the pickling solution comprises 3-5% (volume) of hydrofluoric acid, 15-20% (volume) of nitric acid, 0.5-1% (mass) of corrosion inhibitor, and the balance is deionized water; Step 3, pickling, hang the pretreated titanium felt in the pickling tank with a clamp to ensure that it is completely immersed in the pickling solution, turn on the stirring device, control the speed at 100-200 rpm, control the temperature at 30-40°C, and pickle for 5-15 minutes; Step 4, cleaning.

[0007] Furthermore, the steps of step 1 are: first use a brush or compressed air to remove loose impurities and dust on the surface of the titanium felt, then soak the titanium felt in a suitable organic solvent for 15-30 minutes, stir it appropriately during soaking to enhance the degreasing effect, and then use clean filter paper to absorb the surface organic solvent.

[0008] Furthermore, the pickling solution preparation steps in step 2 are as follows: first add an appropriate amount of deionized water into the pickling tank, slowly add nitric acid according to the formula ratio and stir evenly, then slowly add hydrofluoric acid in a well-ventilated environment while stirring, and finally add the corrosion inhibitor and stir until it is completely dissolved.

[0009] Furthermore, in step 2, the corrosion inhibitor includes hexamethylenetetramine; the concentration of hydrofluoric acid is 40%; and the concentration of nitric acid is 65%.

[0010] Furthermore, the steps of step 4 are as follows: after the pickling is completed, the titanium felt is quickly taken out and placed in the first clean water cleaning tank for soaking and cleaning for 3-5 minutes, during which it is properly stirred to remove the residual acid, and then placed in the subsequent clean water cleaning tank for secondary and multiple cleanings, and washed at least three times to ensure that the acid is completely removed, and finally ultrasonically cleaned with deionized water in an ultrasonic bath for 20 minutes, and finally rinsed with deionized water to complete the cleaning and dried.

[0011] Furthermore, the drying step is: placing the titanium felt into a drying device and drying it at a temperature of 60-80° C. for 1-2 hours until it is completely dry.

[0012] Furthermore, it also includes step 4 testing, which includes appearance testing, weight testing, surface roughness testing and chemical composition analysis In summary, this application has the following beneficial effects: 1. Efficient cleaning: Through the optimized pickling solution formula and process parameters, the oxide scale, oil stains and impurities on the surface of titanium felt can be efficiently removed at the same time, significantly improving the surface quality.

[0013] 2. Low damage: The use of corrosion inhibitors and precise control of parameters such as pickling temperature and time effectively reduce the corrosion of the titanium felt substrate and minimize the damage to its mechanical properties and microstructure.

[0014] 3. Environmental protection and safety: Neutralization, precipitation and other environmentally friendly treatment methods are adopted for waste acid liquid to ensure that it meets the discharge standards. At the same time, safety protection measures and ventilation requirements are emphasized to ensure the safety of operators and environmental friendliness. DETAILED DESCRIPTION

[0015] The technical solutions and effects of the present application are further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the invention, rather than to limit the invention.

[0016] Example 1

[0017] This embodiment discloses a titanium felt surface pickling process, comprising the following steps: Pickling Preparation: Use a plastic pickling tank, a magnetic stirrer, and a heating jacket to control the temperature. Prepare hydrofluoric acid, nitric acid, hexamethylenetetramine corrosion inhibitor, and deionized water. Clean the titanium felt with a brush and then soak it in acetone for 20 minutes to remove oil.

[0018] Pickling solution preparation: The pickling solution consists of 3% hydrofluoric acid (volume), 15% nitric acid (volume), 0.5% corrosion inhibitor (mass), and the balance deionized water. Deionized water is added to the pickling tank, followed by slow addition of nitric acid to 15% of the pickling solution volume. After stirring, slowly add hydrofluoric acid to 3% by volume. Finally, add 0.5% hexamine corrosion inhibitor (mass fraction) and stir thoroughly.

[0019] Pickling process: hang the pretreated titanium felt in the pickling tank, turn on the magnetic stirrer, control the acid solution temperature to 30°C, and the pickling time to 8 minutes.

[0020] Cleaning and drying: After pickling, wash in three clean water cleaning tanks in turn, each washing for 3 minutes, ultrasonically clean with deionized water in an ultrasonic bath for 20 minutes, and finally rinse with deionized water, then place in a hot air drying oven and dry at 60°C for 1 hour.

[0021] Inspection after pickling: After appearance inspection, the oxide scale and impurities on the surface of the titanium felt were completely removed, and the surface was uniform; the weight loss rate was 0.6%; the surface roughness met the requirements of subsequent processing; chemical composition analysis found no new impurity elements introduced.

[0022] Example 2

[0023] This embodiment discloses a titanium felt surface pickling process, comprising the following steps: Pickling Preparation: Use a metal pickling tank lined with acid-resistant material, a mechanical stirrer, and an electric heating rod to control the temperature. Prepare hydrofluoric acid, nitric acid, hexamethylenetetramine corrosion inhibitor, and deionized water. Clean the titanium felt with a brush and then soak it in acetone for 25 minutes to remove oil.

[0024] Preparation of the pickling solution: The pickling solution consists of 5% hydrofluoric acid (volume), 20% nitric acid (volume), 1% corrosion inhibitor (mass fraction), and the balance deionized water. Deionized water is added to the pickling tank, followed by slow addition of nitric acid to a volume fraction of 20% of the pickling solution. After stirring, slowly add hydrofluoric acid to a volume fraction of 5%. Finally, add 1% hexamethylenetetramine corrosion inhibitor (mass fraction) and stir thoroughly.

[0025] Pickling process: put the pretreated titanium felt into the pickling tank, turn on the mechanical stirrer, stir at a speed of 150 rpm, control the temperature at 35°C, and pickle for 12 minutes.

[0026] Cleaning and drying: After pickling, wash in four clean water cleaning tanks in sequence, each washing for 4 minutes, and finally ultrasonically clean with deionized water in an ultrasonic bath for 20 minutes, rinse with deionized water, and place in a vacuum drying oven at 70°C to dry for 1.5 hours.

[0027] Inspection after pickling: The appearance inspection is good, the weight loss rate is 0.8%, the surface roughness meets the requirements, and there is no abnormality in the chemical composition.

[0028] Example 3

[0029] This embodiment discloses a titanium felt surface pickling process, comprising the following steps: Pickling Preparation: Use a metal pickling tank lined with acid-resistant material, a mechanical stirrer, and an electric heating rod to control the temperature. Prepare hydrofluoric acid, nitric acid, hexamethylenetetramine corrosion inhibitor, and deionized water. Clean the titanium felt with a brush and then soak it in acetone for 25 minutes to remove oil.

[0030] Pickling solution preparation: The pickling solution consists of 4% hydrofluoric acid (volume), 17.5% nitric acid (volume), 0.75% corrosion inhibitor (mass), and the balance deionized water. Deionized water is added to the pickling tank, followed by the gradual addition of nitric acid to a volume fraction of 17.5% of the pickling solution. After stirring thoroughly, slowly add hydrofluoric acid to a volume fraction of 4%. Finally, add 0.75% hexamine corrosion inhibitor (mass fraction) and stir thoroughly.

[0031] Pickling process: put the pretreated titanium felt into the pickling tank, turn on the mechanical stirrer, stir at a speed of 200 rpm, control the temperature at 30°C, and pickle for 15 minutes.

[0032] Cleaning and drying: After pickling, wash in four clean water cleaning tanks in sequence, each washing for 4 minutes, and finally ultrasonically clean with deionized water in an ultrasonic bath for 20 minutes, rinse with deionized water, and place in a vacuum drying oven at 70°C to dry for 1.5 hours.

[0033] Inspection after pickling: The appearance inspection is good, the weight loss rate is 0.7%, the surface roughness meets the requirements, and there is no abnormality in the chemical composition.

[0034] Comparative Example 1 The titanium felt was cleaned using hydrofluoric acid (10%), with other conditions being the same as in Example 1. After pickling, some oxide scale remained on the titanium felt surface, with a weight loss rate of 1.5%. The surface roughness increased significantly, affecting subsequent processing.

[0035] Comparative Example 2 A conventional pickling solution formula (5% hydrofluoric acid, 30% nitric acid, no corrosion inhibitor) was used, and other conditions were the same as in Example 2. After pickling, the titanium felt surface showed signs of excessive corrosion, with a weight loss rate of up to 2%, and new impurities contaminated the surface.

[0036] By comparing the examples and the comparative examples, it can be clearly seen that the titanium felt surface pickling process of the present invention has significant advantages in terms of cleaning effect, damage reduction and environmental protection.

[0037] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A titanium felt surface pickling process, characterized in that: The following steps are involved: Step 1, titanium felt pretreatment; Step 2, preparing a pickling solution, wherein the pickling solution comprises 3-5% (volume) of hydrofluoric acid, 15-20% (volume) of nitric acid, 0.5-1% (mass) of corrosion inhibitor, and the balance is deionized water; Step 3, pickling, hang the pretreated titanium felt in the pickling tank with a clamp to ensure that it is completely immersed in the pickling solution, turn on the stirring device, control the speed at 100-200 rpm, control the temperature at 30-40°C, and pickle for 5-15 minutes; Step 4, cleaning.

2. The titanium felt surface pickling process according to claim 1, characterized in that: The steps of step 1 are: first, use a brush or compressed air to remove loose impurities and dust on the surface of the titanium felt, then soak the titanium felt in a suitable organic solvent for 15-30 minutes, stir it appropriately during soaking to enhance the degreasing effect, and then use clean filter paper to absorb the surface organic solvent.

3. The titanium felt surface pickling process according to claim 1, characterized in that: The pickling solution preparation steps in step 2 are as follows: first add an appropriate amount of deionized water into the pickling tank, slowly add nitric acid according to the formula ratio and stir evenly, then slowly add hydrofluoric acid in a well-ventilated environment while stirring, and finally add the corrosion inhibitor and stir until it is completely dissolved.

4. The titanium felt surface pickling process according to claim 1, characterized in that: In step 2, the corrosion inhibitor includes hexamethylenetetramine; the concentration of hydrofluoric acid is 40%; and the concentration of nitric acid is 65%.

5. The titanium felt surface pickling process according to claim 1, characterized in that: The steps of step 4 are as follows: after the pickling is completed, the titanium felt is quickly taken out and placed in the first clean water cleaning tank for soaking and cleaning for 3-5 minutes, and stirred appropriately during the period to remove the residual acid, and then placed in the subsequent clean water cleaning tanks for secondary and multiple cleanings, and washed at least three times to ensure that the acid is completely removed, and finally ultrasonically cleaned with deionized water in an ultrasonic bath for 20 minutes, and finally rinsed with deionized water to complete the cleaning, and dried.

6. The titanium felt surface pickling process according to claim 5, characterized in that: The drying step comprises: placing the titanium felt into a drying device and drying it at a temperature of 60-80° C. for 1-2 hours until it is completely dry.

7. The titanium felt surface pickling process according to claim 1, characterized in that: It also includes step 4 testing, which includes appearance testing, weight testing, surface roughness testing and chemical composition analysis.