Rare earth oxide catalyzed permeation chromium nitride corrosion-resistant coating and preparation method thereof

Abstract

The invention belongs to the field of material surface alloying and coating preparation, and particularly relates to a rare earth oxide catalyzed permeation chromium nitride corrosion-resistant coating and a preparation method thereof. The method comprises the steps that after the surface of a workpiece to be plated is cleaned and preheated, coating slurry is evenly sprayed to the surface of the workpiece, the spraying pressure ranges from 0.5 MPa to 2 MPa, and the thickness of a coating layer ranges from 0.1 mm to 5 mm; and finally, carrying out high-temperature heat treatment to obtain the chromium nitride corrosion-resistant coating. Wherein the solid phase component of the slurry comprises the following components in percentage by weight: 60 to 80 percent of Cr2N, 10 to 30 percent of Al2O3, 1 to 5 percent of NH4Cl, 2 to 4 percent of La2O3 and 2 to 4 percent of Ce2O3. The liquid phase component is prepared from the following components in percentage by weight: 30 to 60 percent of hydroxypropyl methyl cellulose, 20 to 40 percent of MgCl2 solution and 10 to 30 percent of CrO3 solution. The rare earth oxide catalyzed permeation chromium nitride corrosion-resistant coating is uniform in organization structure and moderate in thickness, the permeation layer and a base body are in good metallurgical bonding, falling is not prone to occurring, and the rare earth oxide catalyzed permeation chromium nitride corrosion-resistant coating is suitable for austenitic steel and high-temperature alloy parts used for workpieces with the large length-diameter ratio and various complex shapes such as large boilers and oil and gas field conveying pipelines. And the method has an excellent industrial batch production prospect.

Description

Technical Field

[0001] This invention belongs to the field of material surface alloying and coating preparation, specifically relating to a rare earth oxide-catalyzed chromium nitride corrosion-resistant coating and its preparation method. Background Technology

[0002] Corrosion of high-length-to-diameter flow-through components used in high-temperature fields such as power generation, energy storage, and petrochemicals has become a common industry problem and technical pain point restricting the safe operation of the entire energy equipment sector, resulting in huge losses. Taking the power industry as an example, pipe blockage and rupture accidents caused by oxide scale on the inner wall of flow-through components account for more than 50% of boiler non-shutdown accidents, leading to an increase of more than 20% in the operating and material costs of the unit. Therefore, researching and developing anti-oxidation and corrosion-resistant technologies suitable for the inner and outer wall surfaces of pipes used in boiler units has important practical significance.

[0003] Studies have shown that high-temperature coatings are effective in addressing oxidation corrosion, wear, and high-temperature ablation in components. However, existing high-temperature coating technologies are mostly used for hot-end components such as aero-engine blades, rotors, and turbine disks, which are characterized by high temperatures, short service times, and small dimensions. For the high aspect ratio structures, high-temperature, long-term, and low-stress service environments of flow passage components in energy equipment, existing coating technologies are no longer suitable. The entire industry faces the dilemma of lacking corrosion-resistant coating technologies for the inner walls of flow passage components under ultra-supercritical environments and for preparing coatings for components with large aspect ratios, along with supporting equipment. Therefore, it is necessary to develop a new type of anti-oxidation and corrosion-resistant coating preparation technology and process suitable for workpieces with various complex shapes, including those with large aspect ratios. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing a rare earth oxide-catalyzed chromium nitride corrosion-resistant coating. This method is applicable to the preparation of corrosion-resistant coatings for austenitic steel and high-temperature alloy components with large length-to-diameter ratios and various complex shapes, such as large boilers and oil and gas field pipelines.

[0005] To achieve the above objectives, the present invention adopts the following technical solution.

[0006] A rare earth oxide-catalyzed chromium nitride corrosion-resistant coating slurry comprises the following components: the infiltration source is Cr2N powder, the filler is Al2O3, the activator is NH4Cl, the infiltration catalyst is La2O3 and Ce2O3, the binder is hydroxypropyl methylcellulose, and the curing agents are aqueous solutions of MgCl2 and CrO3.

[0007] Preferably, the coating slurry comprises a solid phase component and a liquid phase component. The solid phase component comprises the following components by mass fraction: 60-80% Cr2N, 10-30% Al2O3, 1-5% NH4Cl, 2-4% La2O3, and 2-4% Ce2O3. The liquid phase component comprises the following components by mass fraction: 30-60% hydroxypropyl methylcellulose, 20-40% MgCl2 solution, and 10-30% CrO3 solution. The concentration of the MgCl2 aqueous solution is 20%, and the concentration of the CrO3 aqueous solution is 5%.

[0008] A method for preparing a rare earth oxide-catalyzed chromium nitride corrosion-resistant coating includes the following steps: Step 1: Weigh the solid phase component and prepare the liquid phase component according to the proportion. Mix the solid phase component and the liquid phase component, and then stir and ball mill to obtain the coating slurry for later use. Step 2: Clean and preheat the surface of the workpiece to be plated, then spray the coating slurry evenly onto the surface of the workpiece, and dry and cure it after coating. Step 3: Place the workpiece after the coating has been cured in an inert atmosphere for high-temperature heat treatment. After cooling, a chromium nitride corrosion-resistant coating is obtained, and the coating residue is treated.

[0009] Preferably, in step 1, the Cr2N powder is sieved through a 1000-mesh sieve, and the solid components are mixed by ball milling in a planetary ball mill at a speed of 350-400 rpm for 6-24 hours.

[0010] Preferably, in step 1, each component in the liquid phase is measured in proportion, thoroughly mixed, stirred, reacted, and filtered to obtain the final product.

[0011] Preferably, in step 1, the preparation method of the coating slurry is as follows: the solid phase component and the liquid phase component are mixed at a solid-liquid ratio of 10g:3-7mL, stirred thoroughly for 2-4h, and then placed in a planetary ball mill for ball milling at a speed of 350-400rpm for 6-24h.

[0012] Preferably, in step 2, the workpiece surface pretreatment process involves cleaning with a high-pressure water gun and rinsing with alcohol or acetone; the preheating treatment is medium-frequency preheating at 220°C for 30-60 minutes.

[0013] Preferably, in step 2, the slurry spraying pressure is 0.5-2 MPa; the coating thickness is 0.1-5 mm; and the coating coverage is not less than 98%.

[0014] Preferably, in step 2, the coating is dried by natural air drying for 24-48 hours, and cured at 300-450℃ for 24-48 hours.

[0015] Preferably, in step 3, the high-temperature heat treatment temperature is 1000-1150℃, the holding time is 10-15min, and the inert gas is Ar or N2.

[0016] The residue is treated by rinsing with a high-pressure water gun or high-pressure airflow and then air-drying naturally.

[0017] Compared with the prior art, the method for preparing a rare earth oxide-catalyzed chromium nitride corrosion-resistant coating of the present invention includes at least the following beneficial effects: 1. This invention achieves a composite infiltration effect by adding rare earth oxides La2O3 and Ce2O3 to the slurry components, thereby improving the infiltration rate and coating quality.

[0018] 2. This invention effectively avoids oxidation, hydrogen embrittlement and other phenomena that may occur in austenitic steel by heat treatment under an inert atmosphere, thus protecting the workpiece matrix while improving the diffusion rate.

[0019] 3. The present invention prepares a coating through a slurry coating process, which is applicable to metal workpieces of various complex shapes and has strong versatility.

[0020] 4. This invention prepares coatings through an integrated production line, which has high coating production efficiency, controllable thickness, and high process repeatability, making it highly practical.

[0021] 5. In this invention, the addition of rare earth oxides can pin grain boundaries, refine matrix structure, improve surface hardness, and enhance the bonding strength between the coating and the base material, based on the diffusion promotion of halides.

[0022] 6. The segmented slurry curing process of natural air drying combined with low-temperature curing in this invention effectively avoids the micro-cracks and micro-pores caused by thermal stress in the slurry layer during direct drying, and enhances the bonding strength between the slurry layer and the workpiece surface.

[0023] 7. In order to prevent the rapid evaporation of the slurry components at high temperatures, the present invention employs rapid heating and short-term heat preservation to heat-treat the workpiece. Attached Figure Description

[0024] Figure 1 This is a cross-sectional morphology diagram of the infiltration layer prepared in Example 2 of the present invention. Detailed Implementation

[0025] The present invention will now be described in detail with reference to specific embodiments.

[0026] A method for preparing a rare earth oxide-catalyzed chromium nitride corrosion-resistant coating includes the following steps: Step 1: Weigh the solid components according to the following mass ratios: 60-80% Cr2N (permeation source), 10-30% Al2O3 (filler), 1-5% NH4Cl (activator), 2-4% La2O3 (permeation catalyst), and 2-4% Ce2O3 (permeation catalyst). The Cr2N powder should be sieved through a 1000-mesh sieve to ensure the total percentage of all solid components is 100%. Place the weighed solid components in a planetary ball mill and ball-mill at 350-400 rpm for 6-24 hours to obtain a uniformly mixed powder. This is the solid phase penetrant; subsequently, 30-60% hydroxypropyl methylcellulose (binder), 20-40% MgCl2 aqueous solution (curing agent) and 10-30% CrO3 aqueous solution (catalyst) are prepared in proportion, and after being fully mixed, stirred, reacted and filtered for 4-8 hours, a liquid phase component is obtained; finally, the solid and liquid phase components are mixed at a solid-liquid ratio of 10g:3-7ml, stirred fully for 2-4 hours, and then placed in a planetary ball mill at 350-400rpm for 6-24 hours. After completion, a uniformly mixed slurry is obtained, which is the coating slurry.

[0027] Step 2: Remove the workpiece to be plated and clean its surface with a high-pressure water gun for 5-10 minutes to remove oil stains, dirt, and oxide scale. Rinse thoroughly with alcohol or acetone to provide a clean, metallic-luster surface for subsequent coating. Then, preheat the workpiece at 220℃ for 30-60 minutes using medium-frequency induction heating. Apply the slurry to the appropriate thickness in one go with a spraying pressure of 0.5-2MPa. Do not apply multiple layers. Maintain a coating thickness of 0.1-5mm and a coverage rate of no less than 98%. If the slurry layer is too thin, it will not provide sufficient penetration; if it is too thick, it will easily crack and peel off, affecting the uniformity of the penetration layer thickness. After coating, allow the workpiece to air dry naturally for 24-48 hours, and then cure it at 300-450℃ for 24-48 hours. The segmented curing process of natural air drying combined with medium and low temperature curing effectively avoids the micro-cracks and micro-pores caused by thermal stress in the slurry layer when directly drying, and enhances the bonding strength between the slurry layer and the workpiece surface.

[0028] Step 3: To prevent rapid evaporation of the slurry components at high temperatures, the workpiece is heat-treated by rapid heating and short-term heat preservation, followed by air cooling to room temperature; the heat treatment temperature is 1000-1150℃, the heat preservation time is 10-15min, and the inert gas is Ar or N2; after the heat treatment is completed, the workpiece surface residue is rinsed with a high-pressure water gun or high-pressure airflow and then air-dried naturally.

[0029] Through the above processes and steps, the present invention provides a method for preparing a rare earth oxide-catalyzed chromium nitride corrosion-resistant coating. Under the condition of adjusting the main process parameters such as the content of solid phase infiltrator, the solid-liquid ratio of slurry, the slurry spraying pressure, the coating thickness, and the heat treatment parameters, a chromium nitride corrosion-resistant coating with a thickness of 22-43 μm and good metallurgical bonding is prepared. The chromium nitride coating obtained by the present invention has a corrosion resistance that is 18-60 times higher than that of the base material in a 600℃ pure water vapor environment and 19-74 times higher than that of the base material in a 650℃ pure water vapor environment. This demonstrates that the chromium nitride corrosion-resistant coating prepared by the method of the present invention effectively improves the corrosion resistance of the alloy base material in a water vapor environment.

[0030] Example 1 A method for preparing a rare earth oxide-catalyzed chromium nitride corrosion-resistant coating includes the following steps: Step 1: Weigh the solid components according to the mass ratio, including 80% Cr2N, 11% Al2O3, 3% NH4Cl, 3% La2O3, and 3% Ce2O3. Place them in a planetary ball mill and ball mill at 400 rpm for 24 hours to obtain a solid phase penetrant. Subsequently, prepare 50% hydroxypropyl methylcellulose, 30% MgCl2 solution, and 20% CrO3 solution according to the proportion. After 8 hours of thorough mixing, stirring, reaction, and filtration, obtain the liquid phase component. Finally, mix the solid and liquid phase components at a solid-liquid ratio of 10g:3ml, stir thoroughly for 4 hours, and then ball mill them in a planetary ball mill at 400 rpm for 24 hours. After completion, a uniformly mixed slurry is obtained, which is the coating slurry.

[0031] Step 2: Clean the surface of the workpiece with a high-pressure water gun for 5 minutes, and rinse it with alcohol or acetone. Then, preheat the workpiece at 220℃ for 45 minutes using medium frequency, and apply the slurry to a thickness of 3mm in one go with a spraying pressure of 2MPa, keeping the coating coverage rate not less than 98%. Then, let the workpiece air dry naturally for 48 hours and cure it at 450℃ for 48 hours.

[0032] Step 3: Place the coated metal pipe under Ar for heat treatment at a temperature of 1000℃ and a holding time of 15 minutes. After completion, rinse the surface of the workpiece with a high-pressure water gun or high-pressure airflow to remove any residue, and then allow it to air dry naturally.

[0033] The process of Examples 2-11 is the same as that of Example 1. Examples 1-11 maintain the same solid phase composition and liquid phase composition. The specific conditions are detailed in Table 1. Table 1 shows the specific parameters of the preparation method of rare earth oxide-catalyzed chromium nitride corrosion-resistant coating in Examples 1-11. By following the preparation steps in Example 1 and the specific preparation parameters in the table, chromium nitride corrosion-resistant coatings of different thicknesses can be obtained. Figure 1 This is a cross-sectional morphology diagram of the infiltration layer prepared in Example 2 of the present invention.

[0034] Table 1. Specific parameters of the preparation method of rare earth oxide-catalyzed chromium nitride corrosion-resistant coating in Examples 1-11

[0035] Analysis of the above embodiments revealed that the thickness of the infiltrated layer was approximately 22-43 μm. Specific results are shown in Table 1. The cross-sectional morphology of the infiltrated layer prepared in Example 2 is shown below. Figure 1 As shown in Table 1 and the cross-sectional morphology, the diffusion layer has a uniform structure and moderate thickness, exhibiting good metallurgical bonding with the substrate and is not easily detached. For the same heat treatment time, the faster the active atom diffusion rate, the greater the thickness of the prepared coating.

[0036] Example 12 A method for preparing a rare earth oxide-catalyzed chromium nitride corrosion-resistant coating includes the following steps: Step 1: Weigh the solid components according to the mass ratio, including 60% Cr2N, 30% Al2O3, 4% NH4Cl, 3% La2O3, and 3% Ce2O3. Place them in a planetary ball mill and ball mill at 400 rpm for 24 hours to obtain a solid phase penetrant. Subsequently, prepare 40% hydroxypropyl methylcellulose, 30% MgCl2 solution, and 30% CrO3 solution according to the proportion. After 8 hours of thorough mixing, stirring, reaction, and filtration, obtain the liquid phase component. Finally, mix the solid and liquid phase components at a solid-liquid ratio of 10g:5ml, stir thoroughly for 4 hours, and then ball mill them in a planetary ball mill at 400 rpm for 24 hours. After completion, a uniformly mixed slurry is obtained, which is the coating slurry.

[0037] Step 2: Clean the surface of the workpiece with a high-pressure water gun for 5 minutes, and rinse it with alcohol or acetone. Then, preheat the workpiece at 220℃ for 45 minutes using medium frequency, and apply the slurry to a thickness of 3mm in one go with a spraying pressure of 2MPa, keeping the coating coverage rate not less than 98%. Then, let the workpiece air dry naturally for 48 hours and cure it at 450℃ for 48 hours.

[0038] Step 3: Place the coated metal pipe under Ar for heat treatment at a temperature of 1050℃ for 15 minutes. After the heat treatment is completed, rinse the surface of the workpiece with a high-pressure water gun or high-pressure airflow to remove any residue, and then let it air dry naturally.

[0039] Example 13 A method for preparing a rare earth oxide-catalyzed chromium nitride corrosion-resistant coating includes the following steps: Step 1: Weigh the solid components according to the mass ratio, including 70% Cr2N, 20% Al2O3, 4% NH4Cl, 3% La2O3, and 3% Ce2O3. Place them in a planetary ball mill and ball mill at 400 rpm for 24 hours to obtain a solid phase penetrant. Subsequently, prepare 55% hydroxypropyl methylcellulose, 30% MgCl2 solution, and 15% CrO3 solution according to the proportion. After 8 hours of thorough mixing, stirring, reaction, and filtration, obtain the liquid phase component. Finally, mix the solid and liquid phase components at a solid-liquid ratio of 10g:5ml, stir thoroughly for 4 hours, and then ball mill them in a planetary ball mill at 400 rpm for 24 hours. After completion, a uniformly mixed slurry is obtained, which is the coating slurry.

[0040] Step 2: Clean the surface of the workpiece with a high-pressure water gun for 5 minutes, and rinse it with alcohol or acetone. Then, preheat the workpiece at 220℃ for 45 minutes using medium frequency, and apply the slurry to a thickness of 3mm in one go with a spraying pressure of 2MPa, keeping the coating coverage rate not less than 98%. Then, let the workpiece air dry naturally for 48 hours and cure it at 450℃ for 48 hours.

[0041] Step 3: Place the coated metal pipe under Ar for heat treatment at a temperature of 1050℃ for 15 minutes. After the heat treatment is completed, rinse the surface of the workpiece with a high-pressure water gun or high-pressure airflow to remove any residue, and then let it air dry naturally.

[0042] Example 14 A method for preparing a rare earth oxide-catalyzed chromium nitride corrosion-resistant coating includes the following steps: Step 1: Weigh the solid components according to the mass ratio, including 70% Cr2N, 20% Al2O3, 2% NH4Cl, 4% La2O3, and 4% Ce2O3. Place them in a planetary ball mill and ball mill at 400 rpm for 24 hours to obtain a solid phase penetrant. Subsequently, prepare 60% hydroxypropyl methylcellulose, 30% MgCl2 solution, and 10% CrO3 solution according to the proportion. After 8 hours of thorough mixing, stirring, reaction, and filtration, obtain the liquid phase component. Finally, mix the solid and liquid phase components at a solid-liquid ratio of 10g:5ml, stir thoroughly for 4 hours, and then ball mill them in a planetary ball mill at 400 rpm for 24 hours. After completion, a uniformly mixed slurry is obtained, which is the coating slurry.

[0043] Step 2: Clean the surface of the workpiece with a high-pressure water gun for 5 minutes, and rinse it with alcohol or acetone. Then, preheat the workpiece at 220℃ for 45 minutes using medium frequency, and apply the slurry to a thickness of 3mm in one go with a spraying pressure of 2MPa, keeping the coating coverage rate not less than 98%. Then, let the workpiece air dry naturally for 48 hours and cure it at 450℃ for 48 hours.

[0044] Step 3: Place the coated metal pipe under Ar for heat treatment at a temperature of 1050℃ for 15 minutes. After the heat treatment is completed, rinse the surface of the workpiece with a high-pressure water gun or high-pressure airflow to remove any residue, and then let it air dry naturally.

[0045] Example 15 A method for preparing a rare earth oxide-catalyzed chromium nitride corrosion-resistant coating includes the following steps: Step 1: Weigh the solid components according to the mass ratio, including 70% Cr2N, 20% Al2O3, 4% NH4Cl, 2% La2O3, and 4% Ce2O3. Place them in a planetary ball mill and ball mill at 400 rpm for 24 hours to obtain a solid phase penetrant. Subsequently, prepare 50% hydroxypropyl methylcellulose, 20% MgCl2 solution, and 30% CrO3 solution according to the proportion. After 8 hours of thorough mixing, stirring, reaction, and filtration, obtain the liquid phase component. Finally, mix the solid and liquid phase components at a solid-liquid ratio of 10g:5ml, stir thoroughly for 4 hours, and then ball mill them in a planetary ball mill at 400 rpm for 24 hours. After completion, a uniformly mixed slurry is obtained, which is the coating slurry.

[0046] Step 2: Clean the surface of the workpiece with a high-pressure water gun for 5 minutes, and rinse it with alcohol or acetone. Then, preheat the workpiece at 220℃ for 45 minutes using medium frequency, and apply the slurry to a thickness of 3mm in one go with a spraying pressure of 2MPa, keeping the coating coverage rate not less than 98%. Then, let the workpiece air dry naturally for 48 hours and cure it at 450℃ for 48 hours.

[0047] Step 3: Place the coated metal pipe under Ar for heat treatment at a temperature of 1150℃ for 10 minutes. After the heat treatment is completed, rinse the surface of the workpiece with a high-pressure water gun or high-pressure airflow to remove any residue, and then let it air dry naturally.

[0048] Example 16 A method for preparing a rare earth oxide-catalyzed chromium nitride corrosion-resistant coating includes the following steps: Step 1: Weigh the solid components according to the mass ratio, including 70% Cr2N, 20% Al2O3, 4% NH4Cl, 4% La2O3, and 2% Ce2O3. Place them in a planetary ball mill and ball mill at 400 rpm for 24 hours to obtain a solid phase penetrant. Subsequently, prepare 45% hydroxypropyl methylcellulose, 40% MgCl2 solution, and 15% CrO3 solution according to the proportion. After 8 hours of thorough mixing, stirring, reaction, and filtration, obtain the liquid phase component. Finally, mix the solid and liquid phase components at a solid-liquid ratio of 10g:5ml, stir thoroughly for 4 hours, and then ball mill them in a planetary ball mill at 400 rpm for 24 hours. After completion, a uniformly mixed slurry is obtained, which is the coating slurry.

[0049] Step 2: Clean the surface of the workpiece with a high-pressure water gun for 5 minutes, and rinse it with alcohol or acetone. Then, preheat the workpiece at 220℃ for 45 minutes using medium frequency, and apply the slurry to a thickness of 3mm in one go with a spraying pressure of 2MPa, keeping the coating coverage rate not less than 98%. Then, let the workpiece air dry naturally for 48 hours and cure it at 450℃ for 48 hours.

[0050] Step 3: Place the coated metal pipe under Ar for heat treatment at a temperature of 1150℃ for 15 minutes. After the heat treatment is completed, rinse the surface of the workpiece with a high-pressure water gun or high-pressure airflow to remove any residue, and then let it air dry naturally.

[0051] Comparative Example 1 The difference between this comparative example and Example 11 is that the solid phase components are replaced with: 80% Cr2N, 11% Al2O3, 3% NH4Cl, 1% La2O3 and 5% Ce2O3.

[0052] Comparative Example 2 The difference between this comparative example and Example 11 is that the solid phase components are replaced with: 80% Cr2N, 11% Al2O3, 3% NH4Cl, 5% La2O3 and 1% Ce2O3.

[0053] Comparative Example 3 The difference between this comparative example and Example 11 is that the solid phase components are replaced with 80% Cr2N, 17% Al2O3, and 3% NH4Cl.

[0054] Table 2. Mass change (mg / cm³) of rare earth oxide-catalyzed chromium nitride corrosion-resistant coatings from Examples 1-11 and Comparative Examples 1-3 in water vapor at 650°C. 2 )

[0055] It can be seen that the chromium nitride coatings prepared in Examples 1 and 4 showed oxidative weight loss in a pure water vapor environment at 650°C, indicating that the oxide film peeled off; the coating prepared in Example 3 showed rapid oxidation after an oxidation time of more than 300 hours, indicating that the coating had poor resistance to high-temperature steam oxidation; the coating prepared in Example 11 had the lowest oxidation rate, and its oxidation weight gain trend followed a parabolic law, indicating that the coating had good oxidation resistance in a pure water vapor environment at 650°C.

[0056] Compared with Example 11, the chromium nitride coating prepared in Comparative Example 3 experienced oxide film peeling in a pure water vapor environment at 650°C, the coating prepared in Comparative Example 2 showed rapid oxidation after an oxidation time of more than 300 hours, and the oxide film of the coating prepared in Comparative Example 1 showed a linear increasing trend with the extension of exposure time. The high-temperature steam oxidation resistance of the coatings all showed varying degrees of deterioration.

[0057] Cross-coated samples were prepared according to the components of Example 11 and Comparative Examples 1-3, respectively. The bonding strength between the coating and the substrate was tested. The interfacial tensile bonding strength of the coating prepared in Example 11 was 24.87 MPa, and the interfacial tensile bonding strengths of the coatings prepared in Comparative Examples 1-3 were 12.26, 15.72 and 8.34 MPa, respectively.

[0058] The rare earth oxide-catalyzed chromium nitride corrosion-resistant coating and its preparation method are applicable to austenitic steel and high-temperature alloy components with large length-to-diameter ratios and various complex shapes, such as large boilers and oil and gas field pipelines. They are highly practical, have a high diffusion rate, excellent film-substrate adhesion, and excellent industrial mass production benefits.

Claims

1. A rare earth oxide-catalyzed chromium nitride corrosion-resistant coating slurry, characterized in that, It includes the following components: the infiltration source is Cr2N powder, the filler is Al2O3, the activator is NH4Cl, the infiltration catalyst is La2O3 and Ce2O3, the binder is hydroxypropyl methylcellulose, and the curing agent is MgCl2 aqueous solution and CrO3 aqueous solution.

2. The rare earth oxide-catalyzed chromium nitride corrosion-resistant coating slurry according to claim 1, characterized in that, The product comprises a solid phase component and a liquid phase component. The solid phase component comprises the following components by mass fraction: 60-80% Cr2N, 10-30% Al2O3, 1-5% NH4Cl, 2-4% La2O3, and 2-4% Ce2O3. The liquid phase component comprises the following components by mass fraction: 30-60% hydroxypropyl methylcellulose, 20-40% MgCl2 aqueous solution, and 10-30% CrO3 aqueous solution; wherein the concentration of the MgCl2 aqueous solution is 20%, and the concentration of the CrO3 aqueous solution is 5%.

3. A method for preparing a rare earth oxide-catalyzed chromium nitride corrosion-resistant coating based on the coating slurry of claim 1 or 2, characterized in that, Includes the following steps: Step 1: Weigh the solid phase component and prepare the liquid phase component according to the proportion. Mix the solid phase component and the liquid phase component, and then stir and ball mill to obtain the coating slurry for later use. Step 2: Clean and preheat the surface of the workpiece to be plated, then spray the coating slurry evenly onto the surface of the workpiece, and dry and cure it after coating. Step 3: Place the workpiece after the coating has been cured in an inert atmosphere for high-temperature heat treatment. After cooling, a chromium nitride corrosion-resistant coating is obtained, and the coating residue is treated.

4. The method for preparing a rare earth oxide-catalyzed chromium nitride corrosion-resistant coating according to claim 3, characterized in that, In step 1, the Cr2N powder is sieved through a 1000-mesh sieve, and the solid components are mixed by ball milling in a planetary ball mill at a speed of 350-400 rpm for 6-24 hours.

5. The method for preparing a rare earth oxide-catalyzed chromium nitride corrosion-resistant coating according to claim 3, characterized in that, In step 1, the components in the liquid phase are prepared in proportion, thoroughly mixed, stirred, reacted, and filtered to obtain the liquid phase component.

6. The method for preparing a rare earth oxide-catalyzed chromium nitride corrosion-resistant coating according to claim 3, characterized in that, In step 1, the coating slurry is prepared as follows: the solid phase component and the liquid phase component are mixed at a solid-liquid ratio of 10g:3-7ml, stirred thoroughly for 2-4 hours, and then placed in a planetary ball mill for ball milling at a speed of 350-400rpm for 6-24 hours, finally obtaining a uniformly mixed coating slurry.

7. The method for preparing a rare earth oxide-catalyzed chromium nitride corrosion-resistant coating according to claim 3, characterized in that, In step 2, the workpiece surface pretreatment process involves cleaning with a high-pressure water gun and rinsing with alcohol or acetone; the preheating treatment is medium-frequency preheating at 220℃ for 30-60 minutes.

8. The method for preparing a rare earth oxide-catalyzed chromium nitride corrosion-resistant coating according to claim 3, characterized in that, In step 2, the slurry spraying pressure is 0.5-2 MPa, the coating thickness is 0.1-5 mm, and the coating coverage is not less than 98%.

9. The method for preparing a rare earth oxide-catalyzed chromium nitride corrosion-resistant coating according to claim 3, characterized in that, In step 2, the coating is dried by natural air drying for 24-48 hours, and cured at 300-450℃ for 24-48 hours.

10. The method for preparing a rare earth oxide-catalyzed chromium nitride corrosion-resistant coating according to claim 1, characterized in that, In step 3, the high-temperature heat treatment temperature is 1000-1150℃, the holding time is 10-15min, and the heat treatment atmosphere is an inert gas Ar or N2.

Images