Three-dimensional ferrous phosphate pigment with corrosion early warning capability and preparation method thereof

Abstract

The present scheme provides a preparation method of a three-dimensional structured ferrous phosphate pigment with corrosion warning capability, comprising the following steps: configuring a ferrous ion-containing solution for providing ferrous ions, wherein the ferrous ion-containing solution contains soluble ferrous salts and surfactants and does not contain oxidizing ions, and the ferrous ion-containing solution is in an acidic environment; configuring an initial mixed solution for providing phosphate ions and ammonium ions; atomizing and spraying the initial mixed solution into the ferrous ion-containing solution to obtain an intermediate mixed solution, and using an ultrasonic oscillation and microwave heating auxiliary device to ultrasonically refine, heat and keep the intermediate mixed solution warm to obtain a final mixed solution; filtering the precipitate in the final mixed solution, and transferring the precipitate to a vacuum environment for high-temperature heating treatment to obtain a three-dimensional structured ferrous phosphate pigment with corrosion warning capability, which can have corrosion warning capability.

Description

Technical Field

[0001] The invention belongs to the technical field of rust-proof inorganic pigment synthesis, and particularly relates to a three-dimensional ferrous phosphate pigment with corrosion early warning capability and a preparation method thereof. Background Art

[0002] Phosphate-based anti-rust pigments occupy an important position in the field of corrosion protection, and their types are rich and varied. According to current research at home and abroad, orthophosphates, phosphites, polyphosphates and complex phosphates are all types that have attracted much attention.

[0003] Among these phosphate-based anti-rust pigments, the first generation of orthophosphate pigments, represented by zinc phosphate, has been very popular in the field of anti-corrosion coatings. Its outstanding green and environmental performance gives it a great advantage in the current increasingly stringent environmental protection requirements. It is also very universal. Whether it is traditional oil-based heavy-duty anti-corrosion coatings or new water-based heavy-duty anti-corrosion coatings, it can be widely used in primers to provide effective anti-rust protection for metal substrates.

[0004] However, industrial progress has put forward higher requirements on anti-corrosion materials, and conventional zinc phosphate pigments have gradually exposed some shortcomings: on the one hand, its hydrolysis degree is relatively low, which leads to its less than ideal passivation ability on the base metal. In actual application scenarios, facing the invasion of corrosive ions, it is difficult for it to fully play a blocking role and cannot effectively resist the corrosion damage caused by these ions to the metal; on the other hand, when corrosive ions and water molecules gradually invade the epoxy coating by penetration, the local zinc phosphate inside the epoxy coating will undergo hydrolysis reaction. This hydrolysis phenomenon will further aggravate the degree of corrosion of the base metal. What is more troublesome is that it is difficult to warn in time from the appearance of the epoxy coating that corrosion has occurred.

[0005] Therefore, the urgent problem to be solved now is how to synthesize a new type of phosphate pigment. This new type of pigment should not only have the function of corrosion warning, and be able to send out a signal when corrosion has just occurred or is about to occur, so that the user can take timely measures, but also have a good corrosion protection effect on corrosive ions, and can effectively block the corrosion of corrosive ions on the metal matrix, thereby providing reliable corrosion protection for metals under harsh conditions such as complex marine environments. It can be said that the successful synthesis of such a new type of phosphate pigment is of great significance for the development of a new generation of anti-corrosion materials that can adapt to the complex marine environment. It will bring new development opportunities to many industries that rely on anti-corrosion materials, such as marine engineering and shipbuilding. Summary of the invention

[0006] The purpose of the present invention is to provide a three-dimensional ferrous phosphate pigment with corrosion warning capability and a preparation method thereof, aiming to solve the problem that phosphate pigments prepared by existing methods are difficult to provide timely warning for corrosion initiation and have insufficient protection against corrosive ion corrosion.

[0007] To achieve the above objectives, the present technical solution provides a method for preparing a three-dimensional ferrous phosphate pigment with corrosion early warning capability, comprising the following steps:

[0008] A ferrous ion-containing solution configured to provide ferrous ions, wherein the ferrous ion-containing solution contains a soluble ferrous salt and a surfactant and does not contain oxidizing ions, and the ferrous ion-containing solution is in an acidic environment;

[0009] configured to provide an initial mixed solution of phosphate ions and ammonium ions, wherein the initial mixed solution contains phosphoric acid, a soluble phosphate, a soluble ammonium salt and an organic solvent;

[0010] The initial mixed solution is atomized and sprayed into a solution containing ferrous ions to obtain an intermediate mixed solution, and the intermediate mixed solution is ultrasonically refined, heated and kept warm using an ultrasonic oscillation and microwave heating auxiliary device to obtain a final mixed solution;

[0011] The precipitate in the final mixed solution is filtered, and the precipitate is transferred to a vacuum environment for high-temperature heating treatment to obtain a three-dimensional ferrous phosphate pigment with corrosion warning capability.

[0012] The present invention provides a three-dimensional ferrous phosphate pigment with corrosion early warning capability, which is prepared according to the preparation method of the three-dimensional ferrous phosphate pigment with corrosion early warning capability.

[0013] Compared with the prior art, this technical solution has the following characteristics and beneficial effects:

[0014] The three-dimensional ferrous phosphate pigment with corrosion warning capability prepared in this scheme has excellent corrosion warning capability. When doped in water-based epoxy coatings, once external oxygen and water molecules penetrate into the interface of the base metal / epoxy coating, the Fe 2+ Will be oxidized to Fe 3+ , producing yellow-brown rust, this obvious color change is very easy to detect. The user can know in time that the base metal protected by the coating may be threatened by corrosion, so as to quickly take anti-corrosion repair measures. It can effectively avoid further deterioration of corrosion, extend the service life of the base metal and its equipment and components, and reduce the safety risks and economic losses caused by failure to detect corrosion in time. And the three-dimensional ferrous phosphate pigment with corrosion warning capability has a three-dimensional structure, which makes it significantly advantageous in anti-corrosion applications. The three-dimensional structure provides a larger specific surface area. When doped in water-based epoxy coatings, the Fe2+ and PO4 3- It can react more fully with the hydrolyzed ions of the base metal, and the generated complex precipitate can better fill the microcracks inside the epoxy coating or form a passivation film on the surface of the substrate, effectively improving the density of the epoxy coating and providing a better barrier to the penetration of corrosive ions, thereby enhancing the overall anti-corrosion performance of the coating and protecting the base metal from corrosion. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the morphology and element distribution of a cactus-shaped ferrous phosphate pigment with corrosion early warning capability according to an embodiment of the present invention.

[0016] Figure 2 This is a scanning electron microscope image of a flower-shaped ferrous phosphate pigment with corrosion warning capability according to an embodiment of the present invention. DETAILED DESCRIPTION

[0017] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0018] Those skilled in the art should understand that, in the disclosure of the present invention, the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

[0019] It is to be understood that the term "one" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element may be one, while in another embodiment, the number of the element may be multiple, and the term "one" should not be understood as a limitation on the quantity.

[0020] This solution provides a method for preparing a three-dimensional ferrous phosphate pigment with corrosion early warning capability, comprising the following steps:

[0021] A ferrous ion-containing solution configured to provide ferrous ions, wherein the ferrous ion-containing solution contains a soluble ferrous salt and a surfactant and does not contain oxidizing ions, and the ferrous ion-containing solution is in an acidic environment;

[0022] configured to provide an initial mixed solution of phosphate ions and ammonium ions, wherein the initial mixed solution contains phosphoric acid, a soluble phosphate, a soluble ammonium salt and an organic solvent;

[0023] The initial mixed solution is atomized and sprayed into a solution containing ferrous ions to obtain an intermediate mixed solution, and the intermediate mixed solution is ultrasonically refined, heated and kept warm using an ultrasonic oscillation and microwave heating auxiliary device to obtain a final mixed solution;

[0024] The precipitate in the final mixed solution is filtered, and the precipitate is transferred to a vacuum environment for high-temperature heating treatment to obtain a three-dimensional ferrous phosphate pigment with corrosion warning capability.

[0025] The ferrous ion solution configured in this scheme uses soluble ferrous salts to provide ferrous ions, surfactants help to disperse, and there are no oxidizing ions to ensure the stability of ferrous ions; phosphoric acid and soluble ammonium salts in the initial mixed solution provide phosphate ions and ammonium ions respectively, and the two are mixed and sprayed by atomization, ultrasonic refinement, microwave heating and heat preservation, and fully react to form ferrous phosphate precipitate with a three-dimensional structure. When it is doped with water-based epoxy coatings, the ferrous phosphate pigment is light blue, and its hydrolysis releases ferrous ions Fe 2+ and phosphate ion PO4 3- , reacts with the matrix metal hydrolyzed ions to form complex precipitation to fill microcracks or form a passivation film, improves the density of the epoxy coating and blocks the penetration of corrosive ions. When external oxygen and water molecules penetrate to the interface, ferrous Fe 2+ Oxidized to ferric iron ion Fe 3+ The yellow-brown rust produced can serve as a corrosion warning due to this obvious color change, thus realizing effective monitoring of the corrosion of the base metal.

[0026] This solution strictly controls the ferrous ion solution to contain no oxidizing ions, so that the ferrous ions can participate in the reaction with the phosphate ions in their original, unoxidized state, and successfully prepares pure and stable ferrous phosphate pigments. When this ferrous phosphate pigment is applied to the anti-corrosion coating system and encounters the situation where external oxygen and water molecules penetrate into the interface of the base metal / epoxy coating, the ferrous ions can undergo oxidation reaction as expected, and the divalent iron ions Fe 2+ Converted to ferric ion Fe 3+ , and then produce obvious yellow-brown rust. This distinct color change can be easily detected by the user, intuitively and promptly reminding the user that the base metal protected by the coating may have been threatened by corrosion, so that maintenance personnel can quickly take corresponding anti-corrosion and repair measures, effectively avoiding further deterioration of corrosion and causing more serious damage to the base metal, greatly extending the service life of the base metal and its equipment, components, etc., while also reducing the potential safety risks and economic losses caused by failure to detect corrosion in time.

[0027] In some embodiments, the soluble ferrous salt contained in the ferrous ion-containing solution provides ferrous ions, and the soluble ferrous salt includes one of ferrous chloride, ferrous sulfate, anhydrous ferrous bromide, ferrous ammonium sulfate, ferrous aminosulfonate, ferrous oxalate, ferrous gluconate dihydrate, ethylenediamine iron (II) sulfate tetrahydrate, or a combination of several of them under compatible conditions.

[0028] In some embodiments, the ferrous ion-containing solution is in an acidic environment. This has the advantage of ensuring that the ferrous ions are stably present in the ferrous ion-containing solution, and effectively inhibiting the hydrolysis of the ferrous ions to form Fe(OH)2 precipitation.

[0029] In some embodiments, the pH value of the ferrous ion-containing solution is 1-5, and is adjusted by adding a pH adjuster. Correspondingly, the pH adjuster is selected from one or more of sulfuric acid, hydrochloric acid, acetic acid, and citric acid.

[0030] The surfactant contained in the ferrous ion solution is a cationic surfactant that does not contain oxidizing ions and can be stably present in an acidic solution to prevent the ferrous ions Fe in the ferrous ion solution from reacting with the ferrous ions Fe in the ferrous ion solution. 2+ The reaction generates a precipitate, and can effectively inhibit the growth and agglomeration of ferrous phosphate crystals, thereby forming ferrous phosphate nanocrystals with smaller sizes. Specifically, cationic surfactants can effectively reduce the surface tension of ferrous ion-containing solutions, so that the various components in the solution, especially ferrous ions, can be more evenly dispersed in the solution system. Evenly dispersed ferrous ions can react with phosphate ions more fully and efficiently, promote the formation of ferrous phosphate precipitation, and help form a more uniform and regular ferrous phosphate crystal structure, ultimately laying the foundation for the preparation of high-quality ferrous phosphate pigments with a three-dimensional structure.

[0031] In some embodiments, the surfactant is selected from one or more of dodecylquinolinium bromide, fatty amine salts, hexadecyltrimethylammonium chloride, and polyquaternary ammonium salts.

[0032] In addition, in order to ensure that ferrous ions exist stably in the ferrous ion solution in an acidic environment without being oxidized in advance, the ferrous ion solution of the present scheme contains a chelating agent, which forms a stable complex with the ferrous ions. The formation of the complex greatly changes the chemical environment of the ferrous ions, changes the distribution of the electron cloud around them, and effectively reduces the redox potential of the ferrous ions. In this way, even if there are some factors that may cause oxidation in the acidic environment, the ferrous ions can rely on the stable complex structure formed with the chelating agent to ensure that they exist stably in the state of ferrous ions; and the stable complex formed by the chelating agent and the ferrous ions shows good solubility and uniform dispersibility in the solution, which enables the ferrous ions to be more evenly distributed in the solution system, rather than having a situation where the local concentration is too high or too low.

[0033] In some embodiments, the complexing agent is selected from one or more of ethylenediaminetetraacetic acid, dimercaptopropanol, sodium dimercaptopropane sulfonate, mercaptoethylamine, and thioglycolic acid.

[0034] Of course, the ferrous ion-containing solution contains deionized water, and the mass ratio of the soluble ferrous salt and the surfactant in the ferrous ion-containing solution is (1:1~5:2). When the ferrous ion-containing solution contains a complexing agent, the mass ratio of the soluble ferrous salt, the complexing agent and the surfactant in the ferrous ion-containing solution is 3:3:1~5:2:1.

[0035] Specifically, in each liter of deionized water, the soluble ferrous salt is 5g~30g, the surfactant is 2g~30g or 10mL~100mL, the complexing agent is 1g~10g or 1mL~20mL, and the pH adjuster is 1g~10g or 1mL~20mL.

[0036] In some embodiments, the ferrous ion solution is placed in an auxiliary device with ultrasonic oscillation and microwave heating functions, and the ultrasonic oscillation frequency is set to 20kHz to 130kHz; the microwave radiation heater power is 100W to 2000W, and the insulation time is 0.1~1h. Ultrasonic oscillation can produce cavitation effect at this frequency, promote uniform dispersion and mixing of substances in the solution, and can also refine ferrous phosphate particles, which is conducive to the formation of uniform crystal nuclei; microwave heating can provide appropriate heat for the solution within the set power range, accelerate the reaction rate, and make the ferrous ions and phosphate ions react more fully. The combination of the two helps to prepare high-quality, three-dimensional ferrous phosphate pigments with good performance.

[0037] In some embodiments, the temperature of the ferrous ion-containing solution is 25°C to 50°C.

[0038] The initial mixed solution of this scheme contains phosphate ions PO4 3- and ammonium ion NH4 +The phosphate ions are used to react with the ferrous ions to form ferrous phosphate, and the ammonium ions are used to slow down the reaction rate of the ferrous ions and the phosphate ions, so as to promote the number of nucleation sites of the ferrous phosphate grains and inhibit the growth of the grains.

[0039] In some embodiments, the phosphoric acid in the initial mixed solution is selected from one or both of orthophosphoric acid and / or metaphosphoric acid. In some embodiments, the soluble phosphate in the initial mixed solution is selected from one of sodium phosphate, ammonium phosphate, potassium phosphate, sodium hydrogen phosphate, ammonium hydrogen phosphate, potassium hydrogen phosphate, sodium dihydrogen phosphate, ammonium dihydrogen phosphate, potassium dihydrogen phosphate, or several combinations thereof under compatible conditions.

[0040] In some embodiments, the soluble ammonium salt is selected from ammonium carbonate, ammonium phosphate, ammonium bicarbonate, ammonium dihydrogen phosphate, ammonium sulfate, ammonium chloride, ammonium tartrate, ammonium oxalate, ammonium formate, ammonium citrate, or a combination of the two under compatible conditions. Adding ammonium salt is to increase the NH4 + concentration, slowing down the ferrous ion Fe in the intermediate mixed solution 2+ and phosphate ions (PO4) 3- The reaction rate increases the number of nucleation sites of ferrous phosphate grains and inhibits grain growth.

[0041] In some embodiments, the organic solvent in the initial mixed solution is selected from one or more of ethanol, polyethylene glycol, and glycerol. By selecting a suitable organic solvent or a combination thereof, the present solution can moderately slow down the reaction rate, give enough time for the ferrous phosphate grains to form more nucleation sites, inhibit the grains from growing too fast, and thus help prepare a three-dimensional ferrous phosphate pigment.

[0042] In some embodiments, the pH value of the initial mixed solution is 1-5, and is adjusted by adding a pH adjuster. Correspondingly, the pH adjuster is selected from one or more of sulfuric acid, phosphoric acid, sodium dihydrogen phosphate, and potassium dihydrogen phosphate.

[0043] In some embodiments, the initial mixed solution is placed in a magnetically stirred water bath, and the stirring speed of the magnetically stirred water bath is 50 r·min -1 Up to 1000 r·min -1, the heating power is 100W to 2000W, the insulation time is 0.1~1h, and the temperature of the initial mixed solution is controlled to be 25℃~50℃. This design can make the components in the initial mixed solution fully and evenly mixed. The continuous and stable stirring force formed by magnetic stirring can effectively break the local concentration unevenness that may occur in the solution, ensure that the components such as phosphoric acid, soluble ammonium salt and selected organic solvent are evenly dispersed, and lay a good foundation for the efficient contact and reaction of various substances in the subsequent mixed reaction with the ferrous ion solution. The temperature between 25℃ and 50℃ also provides a suitable temperature environment for the chemical reaction in the initial mixed solution. Within this temperature range, on the one hand, it can ensure the dissociation of phosphoric acid to provide sufficient phosphate ions for reacting with ferrous ions to form ferrous phosphate; on the other hand, it can also keep the soluble ammonium salt in a suitable state to play its role in slowing down the reaction rate of ferrous ions and phosphate ions, promoting the formation of nucleation sites and inhibiting grain growth.

[0044] In some embodiments, the initial mixed solution contains deionized water, and the mass ratio of phosphoric acid, soluble phosphate and organic solvent in the initial mixed solution is 3:1:2 to 6:1:2. If the initial mixed solution contains soluble ammonium salt, the mass ratio of phosphoric acid, soluble phosphate, soluble ammonium salt and organic solvent in the initial mixed solution is 3:1:1:2 to 6:1:1:2.

[0045] Specifically, in each liter of deionized water, the initial mixed solution contains 0.01L~0.1L of phosphoric acid, 5g~30g of soluble ammonium salt, 5g~30g of soluble phosphate, 10mL~50mL of organic solvent, and 1g~10g or 1mL~20mL of pH adjuster.

[0046] The initial mixed solution is atomized and sprayed into a ferrous ion-containing solution to obtain an intermediate mixed solution, and the intermediate mixed solution is ultrasonically refined, heated and kept warm using an ultrasonic oscillation and microwave heating auxiliary device to obtain a final mixed solution, wherein the ultrasonic oscillation frequency is 20 kHz to 130 kHz; the microwave radiation heater power is 100 W to 2000 W, the intermediate mixed solution temperature is 25° C. to 50° C., and the insulation time is 0.1 h to 24 h.

[0047] In some embodiments, a vacuum filtration device is used to filter the precipitate in the final mixed solution, and the precipitate is placed in a vacuum tube furnace for high-temperature heating treatment. Optionally, the protective gas of the vacuum tube furnace is argon, and the heating temperature is 100°C to 200°C, which promotes the decomposition of the byproduct ammonium ferrous phosphate in the precipitate to form ferrous phosphate. Specifically, argon is an inert gas with stable properties. It will not chemically react with the precipitate during high-temperature heating. It can effectively isolate the air and prevent oxygen and other components in the air from contacting the precipitate and causing oxidation and other adverse phenomena. It ensures that the precipitate follows the expected reaction path during the high-temperature treatment process, which helps to accurately achieve reactions such as the decomposition of the byproduct ammonium ferrous phosphate to form the target product ferrous phosphate.

[0048] The three-dimensional ferrous phosphate pigment with corrosion warning capability finally prepared in the present invention has a three-dimensional spatial structure and is loaded with ferrous ions. When it is doped in a water-based epoxy coating, it appears light blue and has good hydrolysis ability. By releasing Fe 2+ and (PO4) 3- It can react with the hydrolyzed ions of the base metal to form complex precipitation, which fills the microcracks inside the epoxy coating or covers the surface of the base to form a passivation film, which not only effectively improves the density of the epoxy coating, but also has a good barrier effect on the penetration of corrosive ions. In addition, once external oxygen and water molecules penetrate into the base metal / epoxy coating interface, Fe 2+ Will be oxidized to Fe 3+ Later, yellow-brown rust is produced, which plays a good corrosion warning role.

[0049] The following provides design examples of three-dimensional ferrous phosphate pigments with cactus-shaped and flower-shaped structures and corrosion warning capabilities:

[0050] Example 1

[0051] Take a clean beaker with a capacity of 10L, add 1L of deionized water into the beaker, then add 10g of ferrous sulfate, 2g of dodecylquinoline bromide, 5mL of ethylenediaminetetraacetic acid, and 2mL of dilute sulfuric acid (35 wt%) in sequence, use ultrasonic oscillation and microwave heating auxiliary equipment to perform ultrasonic refinement, heating and maintaining the temperature at 50°C, and record it as a ferrous ion-containing solution;

[0052] Take a clean beaker with a capacity of 10L, add 1L of deionized water to the beaker, then add 10mL of phosphoric acid, 10g of ammonium sulfate, and 20mL of polyethylene glycol in sequence, and heat it in a magnetic stirring water bath, maintain the temperature at 50℃, and stir at a speed of 200 r·min -1 ; recorded as the initial mixed solution;

[0053] The initial mixed solution is atomized and sprayed into the ferrous ion-containing solution by an air compressor spray device to form an intermediate mixed solution, and the intermediate mixed solution is further ultrasonically refined and heated by an ultrasonic oscillation and microwave heating auxiliary device and the temperature is maintained at 50° C. to obtain a final mixed solution;

[0054] The precipitate in the final mixed solution is filtered using a vacuum filtration device, and the precipitate is placed in a vacuum tube furnace for high-temperature heating treatment for 3 hours. The protective gas is argon and the heating temperature is 100°C to 200°C. To obtain the cactus-type ferrous phosphate pigment with corrosion warning capability.

[0055] like Figure 1 As shown, Figure 1 This is a schematic diagram of the structure of a cactus-shaped ferrous phosphate pigment with corrosion warning capability, wherein Figure 1 (a) shows the scanning electron microscope image of the cactus-shaped ferrous phosphate pigment with corrosion warning capability. Figure 1 (b1) / (b2) / (b3) in the figure represent the EDS element distribution diagram. It can be seen that the method assisted by ultrasonic oscillation and microwave heating in Example 1 of the present invention can synthesize a cactus-shaped ferrous phosphate pigment with corrosion warning capability. The pigment is doped in water-based epoxy coating and exhibits a light blue color. It has good hydrolysis ability and releases Fe 2+ and (PO4) 3- It can react with the metal ions of the substrate to form a complex precipitate that covers the surface of the substrate to form a passivation film, which not only effectively improves the density of the epoxy coating, but also has a good barrier effect on the penetration of corrosive ions. In addition, once external oxygen and water molecules penetrate into the interface of the substrate metal / epoxy coating, Fe 2+ Will be oxidized to Fe 3+ Then yellow-brown rust is produced, which plays a good corrosion warning role.

[0056] Example 2

[0057] Take a clean beaker with a capacity of 10L, add 1L of deionized water into the beaker, then add 10g of ferrous oxalate, 5g of hexadecyltrimethylammonium chloride, 5mL of thioglycolic acid, and 5mL of oxalic acid (670 wt%) in sequence, use ultrasonic oscillation and microwave heating auxiliary equipment to perform ultrasonic refinement, heating and maintain the temperature at 25°C, and record it as a ferrous ion-containing solution;

[0058] Take a clean beaker with a capacity of 10L, add 1L of deionized water to the beaker, then add 2mL of phosphoric acid, 10g of diammonium phosphate, 5g of ammonium oxalate, and 30mL of ethanol in sequence, and heat it in a magnetic stirring water bath, maintain the temperature at 25℃, and stir at a speed of 200 r·min -1 , recorded as the initial mixed solution;

[0059] The initial mixed solution is atomized and sprayed into the ferrous ion-containing solution by an air compressor spray device to form an intermediate mixed solution, and the intermediate mixed solution is further ultrasonically refined and heated by an ultrasonic oscillation and microwave heating auxiliary device and the temperature is maintained at 25° C. to obtain a final mixed solution;

[0060] The precipitate in the final mixed solution is filtered using a vacuum filtration device, and the precipitate is placed in a vacuum tube furnace for high-temperature heating treatment for 6 hours. The protective gas is argon and the heating temperature is 100°C to 200°C. To obtain the flower-like structure ferrous phosphate pigment with corrosion warning capability.

[0061] like Figure 2 As shown, Figure 2 This is a scanning electron microscope image of a flower-like ferrous phosphate pigment with corrosion warning capability. Figure 2 (a) and (b) in the figure respectively represent scanning electron microscope images at different magnifications. Example 2 of the present invention uses an ultrasonic oscillation and microwave heating-assisted method to synthesize a flower-like ferrous phosphate pigment with corrosion warning capability. The pigment is doped in a water-based epoxy coating to present a light blue color and has good hydrolysis ability. By releasing Fe 2+ and (PO4) 3- It can react with the metal ions of the substrate to form a complex precipitate that covers the surface of the substrate to form a passivation film, which not only effectively improves the density of the epoxy coating, but also has a good barrier effect on the penetration of corrosive ions. In addition, once external oxygen and water molecules penetrate into the interface of the substrate metal / epoxy coating, Fe 2+ Will be oxidized to Fe 3+ Later, yellow-brown rust is produced, which plays a good corrosion warning role.

[0062] The present invention is not limited to the above-mentioned optimal implementation mode. Anyone can derive other various forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, all technical solutions that are the same or similar to those of the present application fall within the protection scope of the present invention.

Claims

1. A method for preparing a three-dimensional ferrous phosphate pigment with corrosion early warning capability, characterized in that: The following steps are involved: A ferrous ion solution is configured to provide ferrous ions, wherein the ferrous ion solution contains a soluble ferrous salt and a surfactant and does not contain oxidizing ions, the surfactant is selected from one or more of dodecylquinoline bromide, fatty amine salts, hexadecyltrimethylammonium chloride, and polyquaternary ammonium salts, and the ferrous ion solution is in an acidic environment; the ferrous ion solution is placed in an auxiliary device with ultrasonic oscillation and microwave heating functions, and the ultrasonic oscillation frequency is set to 20kHz to 130kHz; the microwave radiation heater has a power of 100W to 2000W, the insulation time is 0.1~1h, and the temperature of the ferrous ion solution is 25℃~50℃; The method is configured to provide an initial mixed solution of phosphate ions and ammonium ions, wherein the initial mixed solution contains phosphoric acid, a soluble phosphate, a soluble ammonium salt and an organic solvent, and the pH value of the initial mixed solution is 1-5, and is adjusted by adding a pH adjuster, wherein the pH adjuster is selected from one or more of sulfuric acid, phosphoric acid, sodium dihydrogen phosphate and potassium dihydrogen phosphate; The initial mixed solution is sprayed into a solution containing ferrous ions by atomization to obtain an intermediate mixed solution, and the intermediate mixed solution is ultrasonically refined, heated and kept warm by using an ultrasonic oscillation and microwave heating auxiliary device to obtain a final mixed solution; Filtering the precipitate in the final mixed solution, transferring the precipitate to a vacuum environment for high-temperature heating treatment to obtain a three-dimensional ferrous phosphate pigment with corrosion warning capability, wherein the heating temperature is 100° C. to 200° C.; When it is added to waterborne epoxy coatings, the ferrous phosphate pigment is light blue, and its hydrolysis releases ferrous ions Fe 2+ and phosphate ion PO4 3- , reacts with the matrix metal hydrolyzed ions to form complex precipitation to fill microcracks or form a passivation film. When external oxygen and water molecules penetrate to the interface, ferrous Fe 2+ Oxidized to ferric iron ion Fe 3+ This produces yellow-brown rust.

2. The method for preparing the three-dimensional ferrous phosphate pigment with corrosion early warning capability according to claim 1, characterized in that: The soluble ferrous salt comprises one of ferrous chloride, ferrous sulfate, anhydrous ferrous bromide, ammonium ferrous sulfate, ferrous sulfamate, ferrous oxalate, ferrous gluconate dihydrate, ethylenediamine ferrous sulfate tetrahydrate, or a combination of several of them under compatible conditions.

3. The method for preparing the three-dimensional ferrous phosphate pigment with corrosion early warning capability according to claim 1, characterized in that: The pH value of the ferrous ion-containing solution is 1-5 and is adjusted by adding a pH adjuster, wherein the pH adjuster is selected from one or more of sulfuric acid, hydrochloric acid, acetic acid and citric acid.

4. The method for preparing the three-dimensional ferrous phosphate pigment with corrosion early warning capability according to claim 1, characterized in that: The ferrous ion-containing solution contains a complexing agent, and the complexing agent is selected from one or more of ethylenediaminetetraacetic acid, dimercaptopropanol, sodium dimercaptopropane sulfonate, mercaptoethylamine, and thioglycolic acid.

5. The method for preparing the three-dimensional ferrous phosphate pigment with corrosion early warning capability according to claim 1, characterized in that: The phosphoric acid in the initial mixed solution is selected from one or two of orthophosphoric acid and / or metaphosphoric acid; the soluble phosphate in the initial mixed solution is selected from one of sodium phosphate, ammonium phosphate, potassium phosphate, sodium hydrogen phosphate, ammonium hydrogen phosphate, potassium hydrogen phosphate, sodium dihydrogen phosphate, ammonium dihydrogen phosphate, potassium dihydrogen phosphate, or a combination of several of them under compatible conditions; the soluble ammonium salt is selected from one of ammonium carbonate, ammonium phosphate, ammonium bicarbonate, ammonium dihydrogen phosphate, ammonium sulfate, ammonium chloride, ammonium tartrate, ammonium oxalate, ammonium formate, and ammonium citrate, or a combination of several of them under compatible conditions; the organic solvent in the initial mixed solution is selected from one or more of ethanol, polyethylene glycol, and glycerol.

6. The method for preparing the three-dimensional ferrous phosphate pigment with corrosion early warning capability according to claim 1, characterized in that: The precipitate in the final mixed solution is filtered by a vacuum filtration device, and the precipitate is placed in a vacuum tube furnace for high-temperature heating treatment, wherein the protective gas of the vacuum tube furnace is argon gas, and the heating temperature is 100° C. to 200° C.

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