A nano-material modified coating resistant to high-temperature molten salt corrosion, a preparation method and application thereof

Abstract

A nanomaterial-modified coating resistant to high-temperature molten salt corrosion, its preparation method, and its application are disclosed. The nanomaterial-modified coating comprises the following raw materials in parts by weight: 10-30 wt% graphite, 45-75 wt% resin solution, 5-20 wt% coumarone emulsion, 0.5-2 wt% modified metal oxide, and 0.5-20 wt% additives. The modified metal oxide is obtained by thoroughly mixing a metal oxide with a silane coupling agent. The coumarone emulsion comprises coumarone resin, emulsifier, additives, and water; wherein the solid content is 40-60 wt%, and the particle size of the coumarone resin is ≤800 nm. The resin solution comprises resin and solvent, wherein the resin content is 10-40 wt%. The coating obtained exhibits high resistance to high-temperature molten salt corrosion, meeting the corrosion protection requirements of CSP molten salt systems. A high-temperature corrosion test was conducted at 565℃ for 3000 hours in solar salt, with an annual corrosion rate ≤8 μm / year.

Description

Technical Field

[0001] This invention belongs to the field of high-temperature molten salt corrosion resistant coating technology, specifically relating to a nanomaterial modified coating resistant to high-temperature molten salt corrosion, its preparation method and its application. Background Technology

[0002] Concentrated solar thermal power generation is an important direction for the utilization of new energy sources and one of the largest applications of renewable energy. It is predicted that by 2050, concentrated solar thermal power generation may account for 25% of the world's energy demand. Currently, relatively mature concentrated solar thermal power generation systems use concentrators to focus sunlight onto a solar energy collection device, then use the solar energy to heat an energy storage medium. The sensible heat of the storage medium exchanges heat with water to generate steam, which drives a turbine to generate electricity. Molten salt is one of the most common heat storage media, mainly containing chlorides, nitrates, and carbonates. Molten salt is highly corrosive, primarily because salt ions replace oxygen atoms in the passivation film on the metal surface, thus accelerating the destruction of the passivation film, clogging pipes, and exhibiting extremely strong corrosiveness to heat exchange pipes and other auxiliary facilities.

[0003] Alloy coatings have been proven to meet the corrosion protection requirements of CSP molten salt systems.

[0004] Chinese Patent 202110369854.7 discloses a molten salt corrosion resistant coating comprising a nickel-tantalum active diffusion barrier layer and its preparation method. The high-temperature corrosion resistant coating on the substrate includes a nickel-tantalum inner layer and a pure nickel molten salt corrosion resistant outer layer. By inhibiting the interdiffusion of alloying elements between the coating and the substrate, it extends the service life of the coating. However, due to the high price of its key component element, nickel, its large-scale application prospects are not clear; at the same time, alloy coatings have a fast corrosion rate and insufficient long-term corrosion resistance.

[0005] In recent years, carbon-based coatings have attracted increasing attention from academia and industry due to their excellent high-temperature resistance and low cost. In addition, carbon-based coatings possess other superior properties: good processability, good flowability, low chemical reactivity, and thin coating thickness.

[0006] However, coatings prepared using carbon-based paints exhibit high corrosion rates in high-temperature molten salt environments, failing to meet the stringent requirements for high-temperature corrosion resistance in molten salt environments. Summary of the Invention

[0007] The purpose of this invention is to provide a nanomaterial-modified coating resistant to high-temperature molten salt corrosion, its preparation method, and its application. This improves the high-temperature molten salt corrosion resistance of carbon-based coatings, meets the corrosion protection requirements of CSP molten salt systems, and the coating obtained by this invention can be subjected to a 3000-hour high-temperature corrosion test in solar salt at 565℃, with an annual corrosion rate ≤8μm / year. Moreover, it is low in cost, has excellent comprehensive performance, and is easy to industrialize.

[0008] To achieve the above objectives, the technical solution of the present invention is as follows:

[0009] A nanomaterial-modified coating resistant to high-temperature molten salt corrosion comprises the following raw materials in parts by weight: 10-30 wt% graphite, 45-75 wt% resin solution, 5-20 wt% coumarone emulsion, 0.5-2 wt% modified metal oxide, and 0.5-20 wt% additives.

[0010] The modified metal oxide is obtained by thoroughly mixing a metal oxide with a silane coupling agent;

[0011] The coumarone emulsion comprises coumarone resin, emulsifier, propylene glycol methyl ether and water, wherein the solid content is 40-60 wt% and the particle size of the coumarone resin is ≤800 nm.

[0012] The resin solution comprises resin and solvent, wherein the resin content is 10-40 wt%.

[0013] Preferably, the resin is selected from one or more of epoxy resin, polyester resin, polyurethane resin, alkyd resin, acrylic resin, silicone resin, fluorocarbon resin, polyvinyl alcohol, polyethylene glycol, and phenolic resin.

[0014] Preferably, the solvent is one or more selected from deionized water, n-butanol, ethyl acetate, methanol, isobutanol, and ethanol.

[0015] Preferably, the metal oxide is one or more of titanium oxide, silicon dioxide, zinc oxide, aluminum oxide, zirconium oxide, cerium oxide, and iron oxide.

[0016] Preferably, the particle size of the metal oxide is 1 to 100 nm.

[0017] Preferably, the amount of silane coupling agent added to the modified metal oxide is 0.2-3 wt% of the total weight of the modified metal oxide, and the silane coupling agent is one or more of titanate coupling agents, aluminate coupling agents, epoxy coupling agents, acrylate coupling agents, and quaternary ammonium salt silane coupling agents.

[0018] Preferably, the graphite has a particle size of 1 to 100 μm.

[0019] Preferably, the additives include dispersants, stabilizers, leveling agents, antioxidants, and defoamers.

[0020] The manufacturing method of the high-temperature molten salt corrosion resistant nanomaterial modified coating of the present invention comprises the following steps: adding graphite particles, modified metal oxide powder, coumarone emulsion and additives to a resin solution, and dispersing at high speed for 0.5 to 30 minutes.

[0021] The application of the high-temperature molten salt corrosion resistant nanomaterial modified coating of the present invention is carried out by spraying the coating onto the steel surface, and after drying, a coating thickness of 10-120μm is obtained; the coating is subjected to a high-temperature corrosion test of 3000 hours in solar salt at 565℃, and the annual corrosion rate is ≤8μm / year.

[0022] The coating system described in this invention is an aqueous system. However, traditional coumarone resin has poor compatibility in hydrophilic coatings and cannot act as a "bridge" to allow graphite to disperse well in the system. Therefore, this invention combines coumarone resin with emulsifiers, propylene glycol methyl ether, and water to form a coumarone emulsion, which has better wettability and a better dispersion effect on graphite in hydrophilic coatings.

[0023] The added coumarone emulsion effectively binds to graphite, ensuring a tight bond between the graphite and the coumarone emulsion. This promotes graphite particle dispersion, improves the interfacial bonding between graphite and the resin matrix, enhances stability, and strengthens the barrier effect of graphite against nitrite particles generated by molten salt decomposition, thereby improving the coating's resistance to high-temperature molten salt corrosion. The solid content in the coumarone emulsion should be controlled at 40-60 wt%. Too low a solid content prevents graphite particles from effectively binding with the coumarone, affecting particle dispersion and reducing the coating's resistance to molten salt corrosion. Too high a solid content hinders coumarone resin emulsification, reducing compatibility with both graphite and resin. The coumarone resin particle size should be controlled to ≤800 nm. Larger particle sizes negatively impact dispersion and hinder effective bonding between graphite and the resin matrix.

[0024] The added metal oxides, specifically nano-metal oxides, possess characteristics such as large specific surface area, numerous surface active centers, and excellent corrosion resistance. However, directly adding metal oxides to carbon-based materials results in poor compatibility. This invention utilizes silane coupling agents for modification. These silane coupling agents exhibit excellent surface activity, enabling better surface bonding between metal oxides, resins, and graphite. This significantly improves the compatibility of metal oxides with the resin matrix and graphite, thereby producing an anti-settling effect and enhancing the stability of the coating.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] This invention relates to a resin and graphite anti-corrosion system. Based on this system, coumarone emulsion is added to enhance the interfacial bonding between graphite and the resin matrix, improving the graphite's ability to block nitrite particles generated by molten salt decomposition and thus enhancing the coating's resistance to high-temperature molten salt corrosion. Furthermore, the addition of modified metal oxides improves the compatibility of the metal oxides with the resin and graphite, ensuring uniform distribution of the metal oxides in the coating and enhancing its stability, further improving the coating's resistance to high-temperature molten salt corrosion. The resulting coating underwent a 3000-hour high-temperature corrosion test in solar salt at 565°C, with an annual corrosion rate ≤8 μm / year.

[0027] The raw materials used in this invention are readily available and inexpensive. Compared with conventional molten salt corrosion resistant coatings that incorporate precious metals such as nickel, this invention offers lower costs, higher added value, and greater market potential. Furthermore, compared to traditional carbon-based coatings, it improves corrosion resistance in high-temperature molten salt corrosion environments. Attached Figure Description

[0028] Figure 1 This is a scanning electron microscope image of the coating obtained in Example 1 of the present invention after a 3000-hour corrosion test.

[0029] Figure 2 This is a scanning electron microscope image of the coating obtained in Comparative Example 1 of the present invention after a 3000-hour corrosion test. Detailed Implementation

[0030] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0031] The specific components of the coatings in the embodiments and comparative examples of this invention are shown in Table 1.

[0032] The raw materials were prepared according to the components in Table 1, and then the coating suspension was obtained by high-speed dispersion. The suspension was then applied to the surface of 316 stainless steel sheet to obtain the corresponding coating.

[0033] Corrosion performance testing: In accordance with the "Test and Evaluation Method for Corrosion of Molten Salt in Solar Thermal Power Generation (T / CSTA 19-2021)", a high-temperature corrosion test of 3000 hours was conducted in solar salt at 565℃ to obtain the corrosion rates of the coatings in the invention embodiments and comparative examples, as detailed in Table 2.

[0034] Figure 1 The image shown is a scanning electron microscope (SEM) image of the coating obtained in this embodiment of the invention after a 3000-hour corrosion test. Figure 1 As can be seen, the grinding lines are visible on the surface of the 316 stainless steel sheet.

[0035] Figure 2 This is a scanning electron microscope (SEM) image of the coating obtained in Comparative Example 1 of this invention after a 3000-hour corrosion test. Figure 2 It can be seen that filamentous corrosion products were generated on the surface of the 316 stainless steel sheet, and the grinding lines on the surface of the 316 stainless steel sheet were no longer visible. It is obvious that the coating in Comparative Example 1 is not as effective as that in Example 1 in preventing molten salt corrosion.

[0036] In Comparative Example 1, the coating obtained without the addition of coumarone emulsion showed poor resistance to high-temperature molten salt corrosion.

[0037] The metal oxide used in Comparative Example 2 was not modified with a coupling agent, and the resulting coating had poor resistance to high-temperature molten salt corrosion.

[0038]

[0039]

Claims

1. A nanomaterial-modified coating resistant to high-temperature molten salt corrosion, characterized in that, The raw materials include the following parts by weight: graphite 10-30wt%, resin solution 45-75wt%, coumarone emulsion 5-20wt%, modified metal oxide 0.5-2wt%, and additives 0.5-20wt%. The modified metal oxide is obtained by thoroughly mixing a metal oxide with a silane coupling agent; The coumarone emulsion comprises coumarone resin, emulsifier, additives and water; wherein the solid content is 40-60 wt% and the particle size of the coumarone resin is ≤800 nm. The resin solution comprises resin and solvent, wherein the resin content is 10-40 wt%.

2. The nanomaterial-modified coating resistant to high-temperature molten salt corrosion as described in claim 1, characterized in that, The resin is selected from one or more of epoxy resin, polyester resin, polyurethane resin, alkyd resin, acrylic resin, silicone resin, fluorocarbon resin, polyvinyl alcohol, polyethylene glycol, and phenolic resin.

3. The nanomaterial-modified coating resistant to high-temperature molten salt corrosion as described in claim 1, characterized in that, The solvent is one or more of deionized water, n-butanol, ethyl acetate, methanol, isobutanol, and ethanol.

4. The nanomaterial-modified coating resistant to high-temperature molten salt corrosion as described in claim 1, characterized in that, The metal oxide is one or more of titanium oxide, silicon dioxide, zinc oxide, aluminum oxide, zirconium oxide, cerium oxide, and iron oxide.

5. The nanomaterial-modified coating resistant to high-temperature molten salt corrosion as described in claim 1 or 4, characterized in that, The particle size of the metal oxide is 1–100 nm.

6. The nanomaterial-modified coating resistant to high-temperature molten salt corrosion as described in claim 1, characterized in that, The amount of silane coupling agent added to the modified metal oxide is 0.2-3 wt% of the total weight of the modified metal oxide, and the silane coupling agent is one or more of titanate coupling agents, aluminate coupling agents, epoxy coupling agents, acrylate coupling agents, and quaternary ammonium salt silane coupling agents.

7. The nanomaterial-modified coating resistant to high-temperature molten salt corrosion as described in claim 1, characterized in that, The graphite has a particle size of 1–100 μm.

8. The nanomaterial-modified coating resistant to high-temperature molten salt corrosion as described in claim 1, characterized in that, The additives include dispersants, stabilizers, leveling agents, antioxidants, and defoamers.

9. The method for manufacturing the high-temperature molten salt corrosion-resistant nanomaterial-modified coating as described in any one of claims 1-8, characterized in that, The preparation steps are as follows: graphite particles, modified metal oxide powder, coumarone emulsion, and additives are added to the resin solution and dispersed at high speed. The high-speed dispersion speed is 8000-15000 rpm and the time is 0.5-30 min.

10. The application of a nanomaterial-modified coating resistant to high-temperature molten salt corrosion as described in claim 1, characterized in that, The coating is applied to the steel surface and dried to obtain a coating thickness of 10-120 μm; the coating is subjected to a high-temperature corrosion test in solar salt at 565℃ for 3000 hours, and the annual corrosion rate is ≤8 μm / year.

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