A phosphoric acid-containing graphene oxide modified high-temperature anticorrosion ceramic coating material and a high-temperature anticorrosion ceramic coating

Abstract

The application discloses a phosphoric acid-containing graphene oxide modified high-temperature anticorrosion ceramic coating material and a high-temperature anticorrosion ceramic coating and belongs to the technical field of high-temperature ceramic coating. The coating material preparation raw material comprises a high-temperature anticorrosion ceramic masterbatch and a phosphoric acid-containing graphene oxide dispersion solution, and the masterbatch components are as follows: 20-30% of silicate adhesive; 10-20% of nano-aluminum nitride; 5-10% of boron nitride; 1-5% of talcum powder; 5-10% of zirconium boride; 10-25% of chromium sesquioxide; 10-20% of aluminum oxide; 1-5% of cerium oxide; and the balance of water. The phosphoric acid-containing graphene oxide dispersion solution is directly applied to the high-temperature ceramic coating material, on the one hand, the problem of utilization of wastewater containing phosphoric acid prepared by a chemical method is solved, and on the other hand, the graphene oxide is used as a hydrophilic two-dimensional network structure to improve the properties of the coating, such as high-temperature resistance, oxidation resistance, high strength, high-temperature gas erosion resistance and the like, in cooperation with the high-temperature anticorrosion ceramic masterbatch.

Description

Technical Field

[0001] This invention relates to the field of high-temperature resistant ceramic coating technology, specifically to a phosphoric acid-containing graphene oxide modified high-temperature anti-corrosion ceramic coating material and a high-temperature anti-corrosion ceramic coating. Background Technology

[0002] Xinjiang boasts abundant coal reserves and is a major energy supply region. Therefore, boiler equipment has long played a crucial role in coal combustion processing. However, the high sodium and calcium content in Zhundong coal results in a low melting point. The ash melting behavior, fouling, and coking characteristics significantly impact the normal and stable operation of boilers. Sulfur and chlorine corrosion primarily occurs on the high-temperature heating surfaces of boilers. Sulfur readily causes molten salt corrosion, primarily composed of sulfates, and gaseous corrosion caused by H2S and sulfur oxides. Chlorine mainly corrodes the superheaters of small boilers and the water-cooled walls of the burner area in large boilers, primarily through gaseous corrosion caused by HCl. Corrosion of boiler water-cooled wall tubes can easily lead to thinning of the tube walls and even sudden tube rupture. Furthermore, during combustion, fusible or easily gasifiable substances in pulverized coal particles rapidly volatilize and condense as the temperature decreases. These condensate onto the heating surfaces (furnace walls) and fly ash particles, forming a molten alkali film (coking layer) that adheres to the heating surfaces, affecting heat conduction and reducing coal thermal efficiency, leading to economic losses and safety accidents.

[0003] Traditional solutions to fouling and coking involve regular cleaning and maintenance to prevent or reduce the accumulation of pollutants and deposits. However, boiler shutdowns result in ongoing economic losses and energy consumption for businesses, and safety hazards remain. For high-temperature corrosion, the usual solution is thermal metal spraying, which imparts high-temperature corrosion resistance to the furnace wall. However, thermal metal spraying coatings have low bonding strength with the substrate and poor resistance to reducing atmospheres.

[0004] Introducing phosphoric acid into high-temperature resistant ceramic coatings allows for the formation of phosphate ceramic coatings through chemical bonding. The phosphates undergo condensation reactions upon heating, resulting in a high-hardness, high-heat-resistance, and high-adhesion ceramic coating on the substrate, a crucial method for achieving high-temperature corrosion protection of metals. In the preparation of graphene oxide, concentrated phosphoric acid is used as the oxidant. After oxidation and intercalation, most of the waste acid is removed through ceramic membrane filtration. To recycle this waste liquid, a phosphoric acid-containing graphene oxide dispersion is applied as an additive to the ceramic coating. This not only enables the reuse of recycled resources but also further improves the corrosion resistance and high-temperature resistance of the ceramic coating by introducing phosphoric acid-containing graphene oxide filler.

[0005] Graphene, as a novel additive for functional coatings, can provide high-temperature resistance, corrosion resistance, slag resistance, high thermal conductivity, high electron mobility, and high transparency, while also being impermeable to all gases and salts. However, existing technologies cannot comprehensively achieve all of these functions, and during use, there are varying degrees of weak bonding strength with the substrate, leading to coating cracking and peeling, resulting in short service life of the sprayed coating and causing economic losses to enterprises. Currently, these problems remain unresolved. Summary of the Invention

[0006] The purpose of this invention is to provide a phosphoric acid-containing graphene oxide-modified high-temperature anti-corrosion ceramic coating material and a high-temperature anti-corrosion ceramic coating. This invention provides a phosphoric acid-containing graphene oxide dispersion, which can be directly applied to a high-temperature resistant ceramic coating material. On the one hand, it solves the problem of utilizing phosphoric acid-containing wastewater from the chemical preparation of graphene oxide. On the other hand, by using graphene oxide as a hydrophilic two-dimensional network structure, it further enhances the coating's properties such as high-temperature resistance, oxidation resistance, high strength, and resistance to high-temperature gas corrosion under aqueous phase conditions, in synergistic effect with modified inorganic silicate binders, nano-aluminum nitride, boron nitride, talc, zirconium boride, chromium trioxide, alumina, cerium oxide, and sintering aids. The coating has a compact structure, can isolate corrosive atmospheres, provides a sealing effect, and protects the lining material.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A phosphoric acid-containing graphene oxide-modified high-temperature anti-corrosion ceramic coating material, wherein the raw materials for preparing the coating material include a high-temperature anti-corrosion ceramic masterbatch and a phosphoric acid-containing graphene oxide dispersion, and the high-temperature anti-corrosion ceramic masterbatch comprises the following components by mass percentage:

[0009]

[0010]

[0011] The pH range of the high-temperature corrosion-resistant ceramic masterbatch is 6-8.

[0012] The phosphoric acid-containing graphene oxide dispersion has a phosphoric acid concentration of 0.05-0.3 wt.% and a graphene oxide solid content of 0.8-1.2 wt.%. The phosphoric acid-containing graphene oxide dispersion is prepared using the classic Hummer method, the specific steps of which are detailed in patent CN108840330 B. This method involves selecting a diluent and subjecting it to multiple ceramic filtration membrane processes and vacuum distillation to concentrate and crystallize the dispersion, resulting in a phosphoric acid concentration of 0.05%-0.3% and a graphene oxide solid content of 0.8%-1.2 wt.%.

[0013] The preparation of the phosphoric acid-containing graphene oxide-modified high-temperature anti-corrosion ceramic coating material includes the following steps:

[0014] (1) Prepare a phosphoric acid-containing graphene oxide dispersion;

[0015] (2) Preparation of high temperature anti-corrosion ceramic masterbatch: Silicate binder, nano aluminum nitride, boron nitride, talc powder, zirconium boride, chromium trioxide, aluminum oxide and cerium oxide are added to an electric stirrer in the required proportions, stirred and dispersed for a certain time, and the pH range of the system is adjusted to 6-8. After filtration with a sieve, the high temperature anti-corrosion ceramic masterbatch is obtained, and 200ml is taken out into a beaker.

[0016] (3) Add phosphoric acid-containing graphene oxide dispersion to a beaker in proportion, and continue to use a stirring device to process it for a certain period of time to make it evenly mixed with the masterbatch, thus obtaining the coating material.

[0017] In step (2) above, the stirring speed of the electric mixer is 100-800 rpm and the stirring time is 0.5-5 h.

[0018] In step (3) above, the stirring equipment is an ultrasonic mixer, an electric mixer, or an electromagnetic mixer, with a stirring speed of 100-800 rpm and a stirring time of 0.5-5 h.

[0019] In step (2) above, the sieve is 50-200 mesh.

[0020] Furthermore, the graphene oxide sheet has a diameter of 1-15 μm, 3-50 layers, and an oxygen content of 15-35%.

[0021] A high-temperature anti-corrosion ceramic coating was prepared using the coating material. The preparation process is as follows: the coating material is poured into a spraying machine and evenly coated onto the pretreated pipe. The resulting sample is placed in an oven for a certain period of time and then taken out, thus forming the high-temperature anti-corrosion ceramic coating on the pipe.

[0022] Furthermore, the coating material is applied at a rate of 50-500 g / m². 2 The spraying distance is 20-100cm; the sample drying temperature is 100-600℃, and the drying time is 10-120min.

[0023] The high-temperature anti-corrosion ceramic coating prepared has the following composition by weight percentage: high-temperature anti-corrosion ceramic masterbatch: 92-99.8%; phosphoric acid: 0.1-3%; graphene oxide: 0.1-5%; balance: pure water.

[0024] The design mechanism of this invention is as follows:

[0025] The high-temperature resistant and corrosion-resistant graphene oxide coating prepared by this invention exhibits excellent performance and high bonding strength between the coating and the substrate. The small-particle-size graphene oxide fills the pores and defects in the coating, delaying the diffusion path of corrosive media to a certain extent, thereby inhibiting the penetration of corrosive media into the metal substrate, enhancing the anti-corrosion performance of the coating, and providing good protection for the base metal. Furthermore, by introducing phosphoric acid, a phosphate ceramic coating can be formed through chemical bonding. The phosphate undergoes a condensation reaction upon heating, forming a high-hardness, high-heat-resistant, and high-adhesion ceramic coating on the substrate. The effects are significant in production applications, making it widely applicable to various types of boilers and high-temperature corrosive environments.

[0026] The advantages and beneficial effects of this invention are as follows:

[0027] 1. This invention provides a phosphoric acid-containing graphene oxide dispersion, which can be directly applied to high-temperature resistant ceramic coating materials. On the one hand, it solves the problem of utilizing acidic wastewater from chemical graphene oxide preparation methods. On the other hand, by using graphene oxide as a hydrophilic two-dimensional network structure, it synergistically improves the coating's high-temperature resistance, oxidation resistance, high strength, and resistance to high-temperature gas corrosion with silicon carbide, boron oxide, chromium oxide, and rare earth oxides. The coating structure is compact, effectively isolating corrosive atmospheres and providing a sealing effect to protect the lining material. This invention is of great significance for the technological development and reserve of graphene oxide application products.

[0028] 2. This invention mainly focuses on the preparation method of ceramic coatings for acid-containing dispersions of graphene oxide. This method is of great significance for the downstream application and promotion of graphene oxide and can serve as a reserve of advanced processing technologies for graphene oxide.

[0029] 3. The present invention uses phosphoric acid-containing graphene oxide for modification, and the resulting graphene-modified high-temperature anti-corrosion ceramic coating has the advantages of high temperature resistance, oxidation resistance, high strength, and resistance to high-temperature gas erosion. Attached Figure Description

[0030] Figure 1 Optical images of the samples obtained in Examples 1-4 at 900°C; wherein: (a) Example 1; (b) Example 2; (c) Example 3; (d) Example 4. Detailed Implementation

[0031] To further understand the present invention, the present invention is described below with reference to examples. However, the examples are only for further illustrating the features and advantages of the present invention, and are not intended to limit the scope of the claims of the present invention.

[0032] In the following examples and comparative examples, unless otherwise specified, all quantities and parts are units of mass, and all raw materials and equipment can be purchased from the market.

[0033] In the following examples and comparative examples, the silicate binder is sodium silicate.

[0034] Comparative Example 1:

[0035] (1) Preparation of high temperature anti-corrosion ceramic masterbatch: Weigh 20g sodium silicate, 10g nano aluminum nitride, 5g boron nitride, 1g talc, 5g zirconium boride, 10g chromium trioxide, 10g aluminum oxide and 1g cerium oxide and add them to an electric stirring disperser containing pure water for dispersion.

[0036] (2) Stir at 100 rpm for 30 minutes, filter with a 50-mesh sieve, pour all of it into the spraying machine, and place the pipe at a distance of 30 cm from the spraying machine to spray the slurry evenly onto the pipe.

[0037] (3) After placing the pipe in a vacuum drying oven at 100°C for 20 minutes, take it out and form a masterbatch coating without graphene oxide on the surface of the pipe.

[0038] Example 1:

[0039] (1) Preparation of phosphoric acid-containing graphene oxide dispersion:

[0040] The improved Hummer method is adopted, and the specific steps are described in patent CN 108840330 B. In this method, the diluent is concentrated and crystallized through multiple ceramic filtration membranes and vacuum distillation to control the phosphoric acid concentration in the graphene oxide dispersion to 0.1 wt.% and the solid content of the concentrated graphene oxide to 0.8 wt.%, thus forming a phosphoric acid-containing graphene oxide dispersion for later use.

[0041] (2) Preparation of high-temperature anti-corrosion ceramic coating materials:

[0042] Accurately weigh 20g sodium silicate, 10g nano aluminum nitride, 5g boron nitride, 1g talc, 5g zirconium boride, 10g chromium trioxide, 10g aluminum oxide, and 1g cerium oxide and add them sequentially to an electric mixer. Stir and disperse for a certain period of time, and adjust the pH of the system to 6.5 with pure water. Filter the mixture through a sieve to obtain a high-temperature anti-corrosion ceramic masterbatch, and place it in a beaker. Add 12.5ml of phosphoric acid-containing graphene oxide dispersion and stir with an ultrasonic mixer for 30 minutes to ensure uniform mixing, thus obtaining the compound coating.

[0043] (3) Filter the compounded coating through a 50-mesh sieve and pour it into the sprayer. Place the pipe 30cm away from the sprayer and spray the slurry evenly onto the pipe. Place the pipe in a vacuum drying oven at 100℃ for 20 minutes and then remove it to form a graphene oxide composite coating on the surface of the pipe.

[0044] Example 2:

[0045] (1) Preparation of phosphoric acid-containing graphene oxide dispersion: The preparation method is the same as in Example 1. The phosphoric acid concentration in the obtained phosphoric acid-containing graphene oxide dispersion is 0.1 wt.%, and the solid content of graphene oxide is 0.8 wt.%.

[0046] (2) Preparation of high-temperature anti-corrosion ceramic coating materials:

[0047] Accurately weigh 20g sodium silicate, 10g nano aluminum nitride, 5g boron nitride, 1g talc, 5g zirconium boride, 10g chromium trioxide, 10g aluminum oxide, and 1g cerium oxide and add them sequentially to an electric mixer. Stir and disperse for a certain period of time, and adjust the pH of the system to 6.5 with pure water. Filter the mixture through a sieve to obtain a high-temperature anti-corrosion ceramic masterbatch, and place it in a beaker. Add 25ml of phosphoric acid graphene oxide dispersion and stir with an ultrasonic mixer for 30 minutes to mix it evenly, thus obtaining a compound coating.

[0048] (3) Filter the compounded coating through a 50-mesh sieve and pour it into the sprayer. Place the pipe 30cm away from the sprayer and spray the slurry evenly onto the pipe. Place the pipe in a vacuum drying oven at 100℃ for 20 minutes and then remove it to form a graphene oxide composite coating on the surface of the pipe.

[0049] Example 3:

[0050] (1) Preparation of phosphoric acid-containing graphene oxide dispersion: The preparation method is the same as in Example 1. The phosphoric acid concentration in the obtained phosphoric acid-containing graphene oxide dispersion is 0.1 wt.%, and the solid content of graphene oxide is 0.8 wt.%.

[0051] (2) Preparation of high-temperature anti-corrosion ceramic coating materials:

[0052] Accurately weigh 20g sodium silicate, 10g nano aluminum nitride, 5g boron nitride, 1g talc, 5g zirconium boride, 10g chromium trioxide, 10g aluminum oxide, and 1g cerium oxide, and add them sequentially to an electric mixer. Stir and disperse for a certain period of time, and adjust the pH of the system to 6.5 with pure water. Filter the mixture through a sieve to obtain a high-temperature anti-corrosion ceramic masterbatch, and place it in a beaker. Then add 37.5ml of phosphoric acid-containing graphene oxide dispersion and stir with an ultrasonic mixer for 30 minutes to ensure uniform mixing, thus obtaining the compound coating.

[0053] (3) Filter the compounded coating through a 50-mesh sieve and pour it into the sprayer. Place the pipe 30cm away from the sprayer and spray the slurry evenly onto the pipe. Place the pipe in a vacuum drying oven at 100℃ for 20 minutes and then remove it to form a graphene oxide composite coating on the surface of the pipe.

[0054] Example 4:

[0055] (1) Preparation of phosphoric acid-containing graphene oxide dispersion: The preparation method is the same as in Example 1. The phosphoric acid concentration in the obtained phosphoric acid-containing graphene oxide dispersion is 0.1 wt.%, and the solid content of graphene oxide is 0.8 wt.%.

[0056] (2) Preparation of high-temperature anti-corrosion ceramic coating materials:

[0057] Accurately weigh 20g sodium silicate, 10g nano aluminum nitride, 5g boron nitride, 1g talc, 5g zirconium boride, 10g chromium trioxide, 10g alumina, and 1g cerium oxide, and add them sequentially to an electric mixer. Stir and disperse for a certain period of time, and adjust the pH of the system to 6.5 with pure water. Filter the mixture through a sieve to obtain a high-temperature corrosion-resistant ceramic masterbatch, and place it in a beaker. Then add 125ml of graphene oxide dispersion containing 0.1wt% phosphoric acid, and stir with an ultrasonic mixer for 30 minutes to ensure uniform mixing.

[0058] (3) Filter the compounded coating through a 50-mesh sieve and pour it into the sprayer. Place the pipe 30cm away from the sprayer and spray the slurry evenly onto the pipe. Place the pipe in a vacuum drying oven at 100℃ for 20 minutes and then remove it to form a graphene oxide composite coating on the surface of the pipe.

[0059] High-temperature resistance test of coating: The prepared pipe coating was calcined in a muffle furnace at 400-900℃ to test its high-temperature resistance. The results were obtained by... Figure 1 Analysis revealed that no changes occurred in any of the samples below 700℃. In the comparative sample, surface cracks began to appear at 700℃. Upon reaching 900℃, small areas of the coating on the pipe surface peeled off, with severe spalling. The samples described in Examples 1 and 2 exhibited a higher limiting temperature, with slight cracks appearing at 900℃. However, when the additive amount exceeded 0.5wt%, compared to other samples at the same temperature, the coating began to peel off over a large area, and the degree of peeling was significantly increased.

[0060] Microstructure of the coating: The surface and cross-section of the coating were analyzed using scanning electron microscopy. Experimental results showed that when the amount of GO dispersion added to the coating in the samples described in Examples 1-4 was 0.2 wt%, the coating surface was smooth, without peeling or cracks. No cracks were found between the matrix and the coating at the cross-section, indicating good adhesion.

[0061] High-temperature molten salt corrosion test of the coating: KCl and Na2SO4 were ground and mixed evenly in a mortar and pestle and then placed in a crucible. The samples obtained in Examples 1-4 (coated surface) were placed face down over the crucible and subjected to molten salt vapor corrosion at 600℃ for 8 hours. The coating was observed to show whether it rusted or peeled off. The experimental results showed that the coating layer did not peel off or crack, and the coating had good corrosion resistance.

[0062] Coating hardness test: This experiment adopted the pencil hardness test. The pencil lead was held at a 45° angle to the coating film and advanced forward at a certain pressure and speed. The pencil was repeatedly sharpened until it scratched the coating film five times. The experimental results showed that the scratches on the coating surface were not obvious, and the coating hardness was good.

[0063] Coating-substrate adhesion test: This experiment used a BGD500 / S adhesion tester. A special adhesive was used to directly bond the test column to the coating surface. After the adhesive cured, the bonded test assembly was placed on a WD500 digital display pull-off adhesion tester. A hydraulic pump was used to pull the test column off the coating at a uniform speed not exceeding 1 MPa s⁻¹. The experimental results showed that a force of 12 N was required, further demonstrating the high bonding strength between the coating and the substrate, and its resistance to detachment.

[0064] The graphene-modified high-temperature resistant ceramic coatings prepared in Examples 1-4 and Comparative Example 1 were subjected to performance tests. The appearance and color of the coatings were visually observed. The hemispherical emissivity (blackness), thermal conductivity, adhesion, indentation resistance, heat resistance (1600℃, 100h), abrasion resistance, and salt spray resistance were tested. Scanning electron microscopy analysis was performed on the coatings after salt spray corrosion. The test results are shown in Table 1, and the high-temperature molten salt resistance test results are shown in Table 2. Figure 1 .

[0065] Table 1 Physical Parameters of the Embodiment

[0066]

[0067]

Claims

1. A phosphoric acid-containing graphene oxide-modified high-temperature anti-corrosion ceramic coating material, characterized in that: The raw materials for preparing this coating material include a high-temperature anti-corrosion ceramic masterbatch and a phosphoric acid-containing graphene oxide dispersion. The high-temperature anti-corrosion ceramic masterbatch comprises the following components by mass percentage: Silicate binder 20-30%; Nano-aluminum nitride 10-20%; Boron nitride 5-10%; 1-5% talc; Zirconium boride 5-10%; Chromium trioxide 10-25%; Alumina 10-20%; Cerium oxide 1-5%; Water balance; The pH range of the high-temperature corrosion-resistant ceramic masterbatch is 6-8; the weight ratio of graphene oxide to silicate binder in the phosphoric acid-containing graphene oxide dispersion is (0.1-5):(20-30). The phosphoric acid concentration in the phosphoric acid-containing graphene oxide dispersion is 0.05-0.3 wt.%, and the solid content of graphene oxide is 0.8-1.2 wt.%.

2. The phosphoric acid-containing graphene oxide-modified high-temperature anti-corrosion ceramic coating material according to claim 1, characterized in that: The preparation of this coating material includes the following steps: (1) Prepare a phosphoric acid-containing graphene oxide dispersion; (2) Preparation of high temperature anti-corrosion ceramic masterbatch: Silicate binder, nano aluminum nitride, boron nitride, talc powder, zirconium boride, chromium trioxide, aluminum oxide and cerium oxide are added to an electric stirrer in the required proportions, stirred and dispersed for a certain time, and the pH range of the system is adjusted to 6-8 with pure water. After filtration with a sieve, the high temperature anti-corrosion ceramic masterbatch is obtained, and 200 ml is taken out into a beaker. (3) Add phosphoric acid-containing graphene oxide dispersion to a beaker in proportion, and continue to use a stirring device to process it for a certain period of time to make it evenly mixed with the masterbatch, thus obtaining the coating material.

3. The phosphoric acid-containing graphene oxide-modified high-temperature anti-corrosion ceramic coating material according to claim 2, characterized in that: In step (2), the stirring speed of the electric stirring disperser is 100-800 rpm and the stirring time is 0.5-5 h; in step (3), the stirring equipment is an ultrasonic stirrer, an electric stirrer, or an electromagnetic stirrer, with a stirring speed of 100-800 rpm and a stirring time of 0.5-5 h.

4. The phosphoric acid-containing graphene oxide-modified high-temperature anti-corrosion ceramic coating material according to claim 2, characterized in that: In step (2), the sieve is 50-200 mesh.

5. The phosphoric acid-containing graphene oxide-modified high-temperature anti-corrosion ceramic coating material according to claim 2, characterized in that: The graphene oxide sheets have a diameter of 1-15 μm, 3-50 layers, and an oxygen content of 15-35 wt.%.

6. A high-temperature anti-corrosion ceramic coating prepared using the coating material of claim 1, characterized in that: The preparation process of the high-temperature anti-corrosion ceramic coating is as follows: the coating material is poured into a spraying machine and evenly coated onto the pretreated pipe. The resulting sample is placed in an oven for a certain period of time and then taken out, thus forming the high-temperature anti-corrosion ceramic coating on the pipe.

7. The high-temperature anti-corrosion ceramic coating according to claim 6, characterized in that: The coating material is applied at a rate of 50-500 g / m². 2 The spraying distance is 20-100 cm; the sample drying temperature is 100-600 ℃, and the drying time is 10-120 min.

8. The high-temperature anti-corrosion ceramic coating according to claim 6, characterized in that: The high-temperature anti-corrosion ceramic coating is composed of the following components by weight percentage: high-temperature anti-corrosion ceramic masterbatch: 92-99.8%; Phosphoric acid: 0.1-3%; graphene oxide: 0.1-5%; balance: pure water.

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