Corrosion-resistant and friction-resistant fly ash composite phosphating film and preparation method thereof

Abstract

The present application relates to the field of material science and surface technology, and a kind of corrosion-resistant friction-resistant fly ash composite phosphating film, it is characterized in that, the main component of the corrosion-resistant friction-resistant fly ash composite phosphating film made is phosphating solution, fly ash is used as phosphating accelerator.A kind of corrosion-resistant friction-resistant fly ash composite phosphating film preparation method, it is characterized in that, phosphating solution preparation process: the components of the composite phosphating solution are by phosphoric acid, fly ash, nitrate, dihydrogen phosphate, complexing agent, pH regulator and the balance deionized water according to mass percentage;The above components are added in 1L beaker in order, the beaker with phosphating solution is placed in ultrasonic disperser and is ultrasonic, then it is stirred with glass rod after obtaining the prepared phosphating solution;Phosphating treatment technology: the beaker with the prepared phosphating solution is placed in water bath, and the temperature is raised to 30-40 DEG C, then the metal substrate is placed in beaker, after phosphating treatment, it is taken out, and is repeatedly washed with deionized water 3-6 times, then it is blown dry with cold air after using, and waits for testing.

Description

Technical Field

[0001] This invention relates to the fields of materials science and surface technology, specifically to a corrosion-resistant and friction-resistant fly ash composite phosphating film and its preparation method. Background Technology

[0002] Metals are obtained by absorbing energy from metallic minerals (oxides, sulfides, etc.) through metal smelting. Therefore, metals are thermodynamically unstable and prone to reacting with the surrounding medium to transform into metal ions, resulting in corrosion. The energy difference is the driving force behind the corrosion reaction. Corrosion releases energy and is a spontaneous process that causes irreversible damage to the metal. Metallic materials are widely used in national defense, transportation, construction, and other fields. The annual losses caused by metal corrosion exceed the total losses caused by other natural damage. Furthermore, metal corrosion brings a series of environmental and safety hazards; therefore, the problem of corrosion should not be underestimated. To protect metals, the protection of the metal substrate has been extensively studied, and metal surface treatment is one such area.

[0003] Chemical conversion coating is one of the most commonly used metal surface pretreatment technologies. Chemical conversion involves the reaction of cations dissolved from the metal surface with anions in the conversion solution to form insoluble or sparingly soluble compounds that deposit on the metal substrate surface. Chemical conversion coatings enhance the corrosion resistance of metals and act as an intermediate layer between the metal substrate and subsequent organic coatings, improving the adhesion between them. Among chemical conversion coatings, chromate passivation and phosphating are the two most widely researched and used. However, chromate conversion coatings contain hexavalent chromates, which are highly toxic and may cause gene mutations and are carcinogenic, leading to their prohibition. Phosphating coatings, including zinc-based phosphating, manganese-based phosphating, iron-based phosphating, and zinc-calcium-based phosphating, have become the most widely used metal surface treatment technology in industry. Phosphating technology is now mature, but traditional phosphating conversion films form slowly, requiring the addition of accelerators. Traditional phosphating accelerators are generally nitrates, nitrites, and molybdates, which pollute the environment and are harmful to human health. Therefore, it is necessary to find new phosphating accelerators to replace traditional ones. Furthermore, traditional phosphating requires high-temperature processing, consumes a lot of resources, and produces phosphating films with coarse grains and high porosity that cannot completely cover the metal substrate surface, thus the corrosion resistance of the phosphating film needs further improvement. Phosphating films are also widely used in the phosphating treatment of rotating parts such as bearings, shafts, and gears to improve the wear resistance of these parts. Simultaneously improving the corrosion resistance and friction resistance of the phosphating film is of great practical significance. However, current phosphating solution formulations have not yet addressed the use of fly ash, a solid waste, as a phosphating film-forming accelerator to simultaneously improve the corrosion resistance and friction resistance of the phosphating film. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a corrosion-resistant and friction-resistant fly ash composite phosphate film and its preparation method, thereby solving the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A corrosion-resistant and friction-resistant fly ash composite phosphating film is characterized in that the main component of the corrosion-resistant and friction-resistant fly ash composite phosphating film is phosphating liquid, and fly ash, as a phosphating promoter, is fine ash collected from the flue gas after coal combustion, and its main oxide composition is: SiO2, Al2O3, Fe2O3, CaO, etc.; the hollow glass microspheres are microspheres.

[0007] A method for preparing a corrosion-resistant and friction-resistant fly ash composite phosphate film, characterized by comprising the following steps:

[0008] Step 1, Phosphating solution preparation process: The composite phosphating solution is composed of 1%-3% phosphoric acid, 0.01%-1% fly ash, 8%-20% nitrate, 5%-30% dihydrogen phosphate, 0.02%-1% complexing agent, 0.05%-0.08% pH adjuster, and the balance deionized water by mass percentage. Add the above components to a 1L beaker in sequence, place the beaker containing the phosphating solution in an ultrasonic disperser and sonicate for 30-90 minutes, then stir with a glass rod for 10-20 minutes to obtain the prepared phosphating solution.

[0009] Step 2, Phosphating treatment technology: Place the beaker containing the prepared phosphating solution in a water bath and heat it to 30-40℃. Then place the metal substrate (size: 20×20×1mm) in the beaker. After phosphating for 5-25 minutes, remove it and rinse it repeatedly with deionized water 3-6 times. Then dry it with a cool air blower before testing.

[0010] Preferably, in step 1, the nitrate is one or two of zinc nitrate, calcium nitrate, and manganese nitrate.

[0011] Preferably, in step 1, the dihydrogen phosphate is one or more of zinc dihydrogen phosphate, sodium dihydrogen phosphate, manganese dihydrogen phosphate, and calcium dihydrogen phosphate.

[0012] Preferably, in step 1, the complexing agent is tartaric acid.

[0013] Preferably, in step 1, the pH adjuster is one of sodium hydroxide, ethanolamine, and triethanolamine.

[0014] Preferably, in step 1, the order in which the beaker is added is dihydrogen phosphate, nitrate, phosphoric acid, fly ash, complexing agent, water, and pH adjuster.

[0015] Preferably, in step 2, the metal substrate is one of carbon steel, aluminum alloy, and magnesium alloy.

[0016] Mechanism of the invention:

[0017] This invention provides a fly ash composite phosphating film with corrosion and abrasion resistance properties and its preparation method, using solid waste fly ash (FA) as a phosphating accelerator. The hollow cenospheres of fly ash possess a microspherical morphology, providing excellent adhesion sites for the metal substrate. Mixing fly ash with a phosphating solution to prepare the phosphating film increases the nucleation sites for phosphate crystals on the metal substrate surface. This leads to an increase in both the number of phosphate crystals and the number of nucleation sites. Through continuous growth, the phosphate crystals eventually form a dense grain, resulting in a refined film layer that completely covers the metal substrate surface. Due to the film's dense and low porosity, it effectively prevents corrosive media from penetrating the film and damaging the metal substrate. Furthermore, the dense and fine film layer is key to improving the abrasion resistance of the phosphating film.

[0018] Compared with traditional processes, the present invention has the following advantages:

[0019] (1) This invention is the first to use solid waste fly ash as a phosphating promoter, providing a new way for the resource-based and high-value utilization of solid waste. The hollow microspheres of fly ash have a spherical structure that can increase the nucleation sites in the initial growth stage of the phosphating film, promote the growth rate of phosphate crystals, and require low operating temperature without consuming resources.

[0020] (2) The fly ash composite phosphating film in this invention has both excellent corrosion resistance and friction resistance, the corrosion rate is reduced by one order of magnitude, and the friction coefficient is reduced from 0.5 to 0.1.

[0021] (3) The composite phosphating film in this invention has a dense appearance with low porosity and a smooth and delicate surface.

[0022] (4) This invention provides a new approach for the resource utilization of solid waste fly ash.

[0023] (5) The preparation of the phosphating film of the present invention does not require complex equipment, the steps are simple and the operation is convenient, making it suitable for large-scale industrial production. Attached Figure Description

[0024] Figure 1 These are SEM images (b) of the blank phosphate film (a) and the fly ash composite phosphate film in Example 1.

[0025] Figure 2 This is a comparison chart of the dry friction coefficients of the blank phosphate film and the fly ash composite phosphate film in Example 2.

[0026] Figure 3 This is a Tafel polarization curve of the blank phosphating film and the fly ash composite phosphating film in Example 3. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Example 1

[0029] (1) Take 1% phosphoric acid, 0.2% fly ash (FA), 15% zinc nitrate, 20% manganese dihydrogen phosphate, 0.05% tartaric acid, 0.05% sodium hydroxide and the balance deionized water according to the mass percentage. Add manganese dihydrogen phosphate, zinc nitrate, phosphoric acid, fly ash (FA), tartaric acid, deionized water and sodium hydroxide in the following order to a 1L beaker. Place the beaker containing the phosphating solution in an ultrasonic disperser and sonicate for 60 minutes. Then stir with a glass rod for 10 minutes to obtain the prepared phosphating solution.

[0030] (2) Place the prepared phosphating solution in a water bath and heat it to 40°C. Then place the Q235 iron sheet (20×20×1mm) in a beaker, phosphate it for 10 minutes, take it out, rinse it repeatedly with deionized water 5 times, and then dry it with a cold air blower before testing.

[0031] (3) Performance test of phosphating film: The surface morphology of phosphating film was observed using a field emission electron microscope (FE-SEM, SU-8200, Japan).

[0032] In this invention, the morphology of the phosphating film in Example 1 was characterized using a field emission electron microscope (FE-SEM, SU-8200, Japan). Both the blank phosphating film and the composite phosphating film with added fly ash were characterized. It is clear from the test results that... Figure 1 The blank phosphating film has coarse grains and exposed metal substrate. Figure 2 The SEM image of the phosphate film after adding fly ash shows that the phosphate crystals are small in size and the film layer is dense, completely covering the surface of the metal substrate. The fly ash effectively refines the phosphate crystals.

[0033] Example 2

[0034] (1) The phosphating solution is composed of 1.5% phosphoric acid, 0.5% fly ash (FA), 10% manganese nitrate, 25% manganese dihydrogen phosphate, 1% tartaric acid, 0.08% triethanolamine and the balance deionized water by mass percentage. The above components are added to a 1L beaker in the following order: manganese dihydrogen phosphate, manganese nitrate, phosphoric acid, FA, tartaric acid, deionized water and triethanolamine. The beaker containing the phosphating solution is placed in an ultrasonic disperser and ultrasonicated for 30 minutes. Then it is stirred with a glass rod for 15 minutes to obtain the prepared phosphating solution.

[0035] (2) Phosphating treatment technology: The prepared phosphating solution is placed in a water bath and heated to 35°C. Then, the aluminum alloy (size: 20×20×1mm) is placed in a beaker. After phosphating for 20 minutes, it is taken out and rinsed repeatedly with deionized water 6 times. Then, it is dried with a cold air blower before testing.

[0036] (3) Phosphate film performance test: The friction coefficient of the phosphate film in dry friction was tested using the MRH-3 high-speed ring-block friction and wear tester.

[0037] In this invention, the coefficient of friction of the phosphated film under dry friction was tested using an MRH-3 high-speed ring-block friction and wear testing machine for Example 2. The coefficient of friction under dry friction decreased from 0.5 to 0.1, which clearly shows that the solid waste fly ash composite phosphated film improved the friction resistance of the phosphated film.

[0038] Example 3

[0039] (1) The phosphating solution is composed of 3% phosphoric acid, 0.9% fly ash (FA), 10% calcium nitrate, 5% zinc nitrate, 10% calcium dihydrogen phosphate, 10% zinc dihydrogen phosphate, 1% tartaric acid, 0.05% ethanolamine and the balance deionized water by mass percentage. The above components are added to a 1L beaker in the following order: calcium dihydrogen phosphate, zinc dihydrogen phosphate, calcium nitrate, zinc nitrate, phosphoric acid, FA, tartaric acid, deionized water and ethanolamine. The beaker containing the phosphating solution is placed in an ultrasonic disperser and ultrasonicated for 30 minutes. Then it is stirred with a glass rod for 15 minutes to obtain the prepared phosphating solution.

[0040] (2) Phosphating treatment technology: The prepared phosphating solution is placed in a water bath and heated to 40°C. Then, the magnesium alloy (size: 20×20×1mm) is placed in a beaker. After phosphating for 25 minutes, it is taken out and rinsed repeatedly with deionized water 6 times. Then, it is dried with a cold air blower before testing.

[0041] (3) Phosphate film performance test: The corrosion resistance of the phosphate film was tested using polarization curves and the corrosion rate data was analyzed.

[0042] In this invention, the polarization curve test method in the CHI-660E Shanghai Chenhua electrochemical workstation was used to test the corrosion resistance of the phosphating film in Example 3. After analyzing the corrosion rate data, it can be found that the corrosion rate of the blank phosphating film is 4.41 mpy, and the corrosion rate of the FA composite phosphating film is 0.42 mpy. The corrosion rate is reduced by about one order of magnitude, which shows that fly ash improves the corrosion resistance of the phosphating film.

[0043] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A corrosion-resistant and friction-resistant composite phosphate coating for fly ash, characterized in that, The main component of the corrosion-resistant and friction-resistant fly ash composite phosphating film is phosphating liquid. Fly ash, as a phosphating accelerator, is fine ash collected from the flue gas after coal combustion. Its main oxide composition is: SiO2, Al2O3, Fe2O3, CaO; the hollow glass microspheres have a microsphere morphology. A corrosion-resistant and abrasion-resistant fly ash composite phosphate film includes the following steps: Step 1, Phosphating solution preparation process: The phosphating solution is composed of 1%-3% phosphoric acid, 0.01%-1% fly ash, 8%-20% nitrate, 5%-30% dihydrogen phosphate, 0.02%-1% complexing agent, 0.05%-0.08% pH adjuster, and the balance deionized water by mass percentage. Add the above components to a 1 L beaker in sequence, place the beaker containing the phosphating solution in an ultrasonic disperser and sonicate for 30-90 min, then stir with a glass rod for 10-20 min to obtain the prepared phosphating solution. Step 2, Phosphating treatment technology: Place the beaker containing the prepared phosphating solution in a water bath and heat it to 30-40 ℃. Then place the metal substrate in the beaker and phosphate for 5-25 minutes. After that, take it out and rinse it repeatedly with deionized water 3-6 times. Then dry it with a cool air blower before testing.

2. The corrosion-resistant and abrasion-resistant fly ash composite phosphate film according to claim 1, characterized in that: In step 1, the nitrate is one or two of zinc nitrate, calcium nitrate, and manganese nitrate.

3. The corrosion-resistant and abrasion-resistant fly ash composite phosphate film according to claim 1, characterized in that: In step 1, the dihydrogen phosphate is one or more of zinc dihydrogen phosphate, sodium dihydrogen phosphate, manganese dihydrogen phosphate, and calcium dihydrogen phosphate.

4. The corrosion-resistant and abrasion-resistant fly ash composite phosphate film according to claim 1, characterized in that: In step 1, the complexing agent is tartaric acid.

5. The corrosion-resistant and abrasion-resistant fly ash composite phosphate film according to claim 1, characterized in that: In step 1, the pH adjuster is one of sodium hydroxide, ethanolamine, and triethanolamine.

6. The corrosion-resistant and abrasion-resistant fly ash composite phosphate film according to claim 1, characterized in that: In step 1, the order in which the beaker is added is: dihydrogen phosphate, nitrate, phosphoric acid, fly ash, complexing agent, water, and pH adjuster.

7. The corrosion-resistant and abrasion-resistant fly ash composite phosphate film according to claim 1, characterized in that: In step 2, the metal substrate is one of carbon steel, aluminum alloy, and magnesium alloy.

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