Modification method for improving corrosion resistance of chromium-nickel cladding coating and chromium-nickel cladding coating

Abstract

The invention discloses a modification method for improving corrosion resistance of a chromium-nickel cladding coating and the chromium-nickel cladding coating, cladding powder is prepared according to a mass ratio, and after the surface of a workpiece to be plated is cleaned, the chromium-nickel corrosion-resistant coating is prepared through plasma cladding; wherein the solid-phase cladding powder comprises the following components in percentage by mass: 30 to 70 percent of Cr, 15 to 45 percent of Ni, 2 to 5 percent of V, 2 to 5 percent of Hf, 0 to 5 percent of NH4Cl and 2 to 5 percent of La2O3. According to the modification method for improving the corrosion resistance of the chromium-nickel cladding coating, the prepared infiltrated layer is uniform in organization structure, moderate in thickness, sufficient in Cr atom diffusion, good in metallurgical bonding with a base body, not prone to falling off and 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 excellent industrial batch production benefits.

Description

Technical Field

[0001] The invention belongs to the field of material surface alloying and coating preparation, and specifically relates to a modification method for improving the corrosion resistance of a chromium-nickel cladding coating and a chromium-nickel cladding coating. Background Art

[0003] In the thermal power generation industry, the corrosion problem of boiler unit pipelines in high-temperature sulfur-containing flue gas environments is one of the main problems of high operating costs; Cr2O3 is a common high-temperature coating material, which is usually used to improve the corrosion resistance of materials in high-temperature environments. It has excellent high-temperature stability, good oxidation resistance and chemical inertness, and can protect the substrate from corrosion. However, Cr2O3 has poor stability in steam above 600°C, and the loose oxide film caused by volatile products will cause the oxide film to peel off; in addition, the Cr content in the alloy matrix is ​​relatively low. As the service time increases, when the Cr content required for the growth of the oxide film cannot be supplemented, the oxidation resistance of the alloy will also drop sharply. Therefore, it is of great practical significance to study and develop new corrosion-resistant and oxidation-resistant coatings suitable for the inner and outer wall surfaces of pipelines for boiler units. Summary of the invention

[0004] The embodiments of the present invention aim to solve at least one of the technical problems existing in the prior art, and provide a modification method for improving the corrosion resistance of a chromium-nickel cladding coating and a chromium-nickel cladding coating. The method is suitable for the preparation of corrosion-resistant coatings of austenitic steel and high-temperature alloy parts used for large boilers, oil and gas field transportation pipelines and various complex-shaped workpieces.

[0005] To achieve the above object, the technical solution adopted by the present invention is a modification method for improving the corrosion resistance of the chromium-nickel cladding coating, comprising the following steps:

[0006] Step 1, weigh and prepare the solid phase components of the chromium-nickel cladding powder according to the mass ratio, and prepare the solid phase cladding penetrant after stirring, ball milling and drying for use;

[0007] Step 2: clean the workpiece to be plated and pour a sufficient amount of cladding powder into the feeding port;

[0008] Step 3: Placing the workpiece to be plated in an inert atmosphere for plasma cladding, obtaining a chromium-nickel cladding coating after cooling, and performing cladding residue treatment.

[0009] In some embodiments of the present invention, in step 1, the infiltration source includes Cr and Ni, the modifier includes V and Hf, the activator includes NH4Cl, and the catalyst includes La2O3, wherein the Cr and Ni powders are sieved through a 1000 mesh sieve.

[0010] In some embodiments of the present invention, in step 1, the solid phase components are weighed by mass percentage, including 30-70% Cr, 15-45% Ni, 2-5% V and Hf, 0-5% NH4Cl and 2-5% La2O3.

[0011] In some embodiments of the present invention, in step 1, the solid phase components are wet-milled and mixed in a planetary ball mill and then dried, the ball milling medium is anhydrous ethanol, the ball milling speed is 350-400 rpm, the time is 12-24 hours, and the drying is vacuum drying at 80-120°C for 12-24 hours.

[0012] In some embodiments of the present invention, in step 2, during the workpiece surface pretreatment process, the workpiece surface is cleaned by a high-pressure water gun and rinsed with alcohol or acetone.

[0013] In some embodiments of the present invention, in step 3, in the plasma cladding process, the cladding current is 80-120A, the feed rate is 18-22g / min, the scanning rate is 20-40cm / min, the nozzle height is 8-12mm, the rotation speed is 2-5r / min, the ion gas flow rate is 0.2-0.3L / min, the protective gas flow rate is 18-20L / min, and the inert gas is Ar or N2; the residue is treated by flushing with a high-pressure water gun or a high-pressure air flow, and naturally dried.

[0014] The present invention also proposes a chromium-nickel cladding coating with improved corrosion resistance. The chromium-nickel cladding coating is prepared according to the modification method for improving the corrosion resistance of the chromium-nickel cladding coating described in any of the above embodiments. The solid phase components of the chromium-nickel cladding coating are weighed by mass percentage and include 30-70% Cr, 15-45% Ni, 2-5% V, 2-5% Hf, 0-5% NH4Cl and 2-5% La2O3.

[0015] Compared with the prior art, the modification method of the present invention for improving the corrosion resistance of the chromium-nickel cladding coating also includes at least the following beneficial effects:

[0016] 1. The present invention prepares the chromium-nickel cladding coating by plasma cladding process, which has concentrated heat, short action time, small thermal impact in the cladding area, and high bonding strength between the coating and the base material;

[0017] 2. The present invention adds NH4Cl and La2O3 to the cladding powder components, which has the effect of promoting infiltration and activation, thereby improving the infiltration rate and the quality of the chromium-nickel cladding coating;

[0018] 3. The present invention adds V element to the cladding powder component, which can reduce the generation of network chromium carbide during the treatment process, making the formed corrosion-resistant coating denser;

[0019] 4. The present invention adds Hf element to the cladding powder component, and HfO2 can be formed during the treatment process, which plays a role in pinning the oxide layer and improving the bonding strength between the coating and the substrate;

[0020] 5. The present invention prepares the chromium-nickel cladding coating through an integrated production line. The chromium-nickel cladding coating has high production efficiency, controllable thickness, high process repeatability, and is extremely practical.

[0021] Furthermore, the addition of rare earth oxide La2O3 can pin grain boundaries, refine matrix structure, improve surface hardness, and enhance the bonding strength between coating and base material in the form of second phase precipitation on the basis of halide-promoted diffusion.

[0022] Furthermore, the addition of the modifying element Hf can aggregate at the oxide grain boundaries and hinder further oxidation of the base material. Its oxidation product HfO2 can pin the oxide film and enhance the anti-stripping performance of the oxide, thereby improving the oxidation resistance and corrosion resistance of the chromium-nickel cladding coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a cross-sectional morphology diagram of the chromium-nickel cladding coating in Example 1 of the present invention. DETAILED DESCRIPTION

[0024] The present invention is described in detail below in conjunction with relevant specific implementation methods.

[0025] The present invention proposes a modification method for improving the corrosion resistance of a chromium-nickel cladding coating, comprising the following steps:

[0026] Step 1, weighing the solid phase components according to the mass ratio, including 30-70% Cr, 15-45% Ni, 2-5% V and Hf, 0-5% NH4Cl and 2-5% La2O3, specifically, Cr and Ni are infiltration sources, V and Hf are modifiers, NH4Cl is an activator, La2O3 is a catalyst, wherein Cr and Ni powders are sieved through a 1000 mesh sieve to keep the total percentage of all solid phase components at 100%; placing the weighed solid phase components in a planetary ball mill at 350-400rpm and wet-grinding with ethanol for 12-24h, and then vacuum drying at 80-120℃ for 12-24h to obtain a uniformly mixed powder, i.e., the cladding powder.

[0027] Step 2: Take out the workpiece to be plated, clean the surface with a high-pressure water gun for 5-10 minutes to remove oil stains, dust, etc. on the surface of the workpiece and remove the oxide scale, and rinse it with alcohol or acetone to provide a clean and metallic surface for subsequent cladding.

[0028] Step 3. The plasma cladding process parameters are: cladding current is 80-120A, feed rate is 18-22g / min, scanning rate is 20-40cm / min, nozzle height is 8-12mm, rotation speed is 2-5r / min, ion gas flow rate is 0.2-0.3L / min, shielding gas flow rate is 18-20L / min, and inert gas is Ar; after cladding, rinse the surface residue of the workpiece with a high-pressure water gun and dry it naturally.

[0029] Through the above-mentioned processes and steps, a modification method for improving the corrosion resistance of the chromium-nickel cladding coating of the present invention is provided. Under the conditions of adjusting the main process parameters such as the cladding powder composition and the plasma cladding parameters, a chromium-nickel cladding coating with a thickness of 0.45-1.55 mm and good metallurgical bonding is prepared; the chromium-nickel cladding coating obtained by the present invention has a corrosion resistance that is 18-62 times higher than that of the parent material in a 600°C pure water vapor environment and a corrosion resistance that is 20-84 times higher than that of the parent material in a 650°C pure water vapor environment, which indicates that the chromium-nickel cladding coating prepared by the method of the present invention effectively improves the corrosion resistance of the alloy parent material in a water vapor environment.

[0030] The present invention also proposes a chromium-nickel cladding coating with improved corrosion resistance. The chromium-nickel cladding coating is prepared according to the modification method for improving the corrosion resistance of the chromium-nickel cladding coating described in any of the above embodiments. The solid phase components of the chromium-nickel cladding coating are weighed by mass percentage and include 30-70% Cr, 15-45% Ni, 2-5% V, 2-5% Hf, 0-5% NH4Cl and 2-5% La2O3.

[0031] Example 1

[0032] Step 1: Weigh the solid phase components according to mass proportion, including 45% Cr, 45% Ni, 2% V, 3% Hf, 2% NH4Cl and 3% La2O3, place them in a planetary ball mill for wet grinding with ethanol at 400 rpm for 24 hours, and then vacuum dry them at 100°C for 24 hours to obtain cladding powder.

[0033] Step 2: Use a high-pressure water gun to clean the surface of the workpiece for 5 minutes, and then rinse it with alcohol or acetone.

[0034] Step 3. The plasma cladding process parameters are: cladding current is 120A, feed rate is 20g / min, scanning rate is 35cm / min, nozzle height is 10mm, rotation speed is 2r / min, ion gas flow rate is 0.2L / min, shielding gas flow rate is 19L / min, and inert gas is Ar or N2; after cladding, rinse the surface residue of the workpiece with a high-pressure water gun or high-pressure air flow, and dry it naturally.

[0035] The processes of Examples 2 to 11 are the same as those of Example 1. Examples 1 to 11 maintain the same ratio of the penetrant components. The specific conditions are shown in Table 1. Table 1 is the specific parameters of Examples 1 to 11 of the plasma chromium-nickel cladding coating preparation method. According to the preparation steps in the above Example 1 and the specific preparation parameters in the table, chromium-nickel corrosion-resistant coatings of different thicknesses can be obtained.

[0036] Table 1

[0037]

[0038]

[0039] By analyzing and studying the above examples, the thickness of the infiltration layer is measured to be about 0.45-1.55 mm. The specific results are shown in Table 1. The cross-sectional morphology of the infiltration layer is as follows: Figure 1 As shown in Table 1 and the cross-sectional morphology, it is found that the diffusion layer has a uniform structure, moderate thickness, sufficient diffusion of Cr atoms, a good metallurgical bond between the diffusion layer and the matrix, and is not easy to fall off.

[0040] Example 12

[0041] Step 1: Weigh the solid phase components according to mass proportion, including 70% Cr, 15% Ni, 5% V, 5% Hf, 2% NH4Cl and 3% La2O3, place them in a planetary ball mill for wet grinding with ethanol at 350 rpm for 24 hours, and then vacuum dry them at 100°C for 24 hours to obtain the cladding powder.

[0042] Step 2: Use a high-pressure water gun to clean the surface of the workpiece for 5 minutes, and then rinse it with alcohol or acetone.

[0043] Step 3. The plasma cladding process parameters are: cladding current is 80A, feed rate is 20g / min, scanning rate is 40cm / min, nozzle height is 12mm, rotation speed is 3r / min, ion gas flow rate is 0.2L / min, shielding gas flow rate is 19L / min, and inert gas is Ar or N2; after cladding, rinse the surface residue of the workpiece with a high-pressure water gun or high-pressure air flow, and dry it naturally.

[0044] Embodiment 13

[0045] Step 1: Weigh the solid phase components according to mass proportion, including 50% Cr, 30% Ni, 5% V, 5% Hf, 5% NH4Cl and 5% La2O3, place them in a planetary ball mill for wet grinding with ethanol at 400 rpm for 24 hours, and then vacuum dry them at 100°C for 24 hours to obtain cladding powder.

[0046] Step 2: Use a high-pressure water gun to clean the surface of the workpiece for 5 minutes, and then rinse it with alcohol or acetone.

[0047] Step 3. The plasma cladding process parameters are: cladding current is 100A, feed rate is 18g / min, scanning rate is 35cm / min, nozzle height is 10mm, rotation speed is 3r / min, ion gas flow rate is 0.2L / min, shielding gas flow rate is 19L / min, and inert gas is Ar; after cladding, rinse the surface residue of the workpiece with a high-pressure water gun and dry it naturally.

[0048] Embodiment 14

[0049] Step 1: Weigh the solid phase components according to mass proportion, including 70% Cr, 20% Ni, 2% V, 3% Hf, 2% NH4Cl and 3% La2O3, place them in a planetary ball mill for wet grinding with ethanol at 400 rpm for 24 hours, and then vacuum dry them at 100°C for 24 hours to obtain cladding powder.

[0050] Step 2: Use a high-pressure water gun to clean the surface of the workpiece for 5 minutes, and then rinse it with alcohol or acetone.

[0051] Step 3. The plasma cladding process parameters are: cladding current is 120A, feed rate is 20g / min, scanning rate is 35cm / min, nozzle height is 10mm, rotation speed is 2r / min, ion gas flow rate is 0.2L / min, shielding gas flow rate is 19L / min, and inert gas is Ar; after cladding, rinse the surface residue of the workpiece with a high-pressure water gun and dry it naturally.

[0052] Embodiment 15

[0053] Step 1: Weigh the solid phase components according to mass proportion, including 55% Cr, 30% Ni, 2% V, 3% Hf, 5% NH4Cl and 5% La2O3, place them in a planetary ball mill for wet grinding with ethanol at 400 rpm for 24 hours, and then vacuum dry them at 100°C for 24 hours to obtain cladding powder.

[0054] Step 2: Use a high-pressure water gun to clean the surface of the workpiece for 5 minutes, and then rinse it with alcohol or acetone.

[0055] Step 3. The plasma cladding process parameters are: cladding current is 120A, feed rate is 20g / min, scanning rate is 35cm / min, nozzle height is 10mm, rotation speed is 2r / min, ion gas flow rate is 0.2L / min, shielding gas flow rate is 19L / min, and inert gas is Ar; after cladding, rinse the surface residue of the workpiece with a high-pressure water gun and dry it naturally.

[0056] Example 16

[0057] Step 1: Weigh the solid phase components according to mass proportion, including 55% Cr, 35% Ni, 2% V, 3% Hf, 2% NH4Cl and 3% La2O3, place them in a planetary ball mill for wet grinding with ethanol at 400 rpm for 24 hours, and then vacuum dry them at 100°C for 24 hours to obtain cladding powder.

[0058] Step 2: Use a high-pressure water gun to clean the surface of the workpiece for 5 minutes, and then rinse it with alcohol or acetone.

[0059] Step 3. The plasma cladding process parameters are: cladding current is 120A, feed rate is 20g / min, scanning rate is 35cm / min, nozzle height is 10mm, rotation speed is 2r / min, ion gas flow rate is 0.2L / min, shielding gas flow rate is 19L / min, and inert gas is Ar; after cladding, rinse the surface residue of the workpiece with a high-pressure water gun and dry it naturally.

[0060] The modification method for improving the corrosion resistance of the chromium-nickel cladding coating in the present invention is suitable for austenitic steel and high-temperature alloy parts used in large boilers, oil and gas field transportation pipelines and other workpieces with large aspect ratios and various complex shapes. It has strong practicality, high permeation rate, excellent membrane-base bonding, and extremely good industrial mass production benefits.

[0061] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, but the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A modification method for improving the corrosion resistance of chromium-nickel cladding coating, characterized in that: The following steps are involved: Step 1, weigh and prepare the solid phase components of the chromium-nickel cladding powder according to the mass ratio, and prepare the solid phase cladding penetrant after stirring, ball milling and drying; Step 2: clean the workpiece to be plated and pour a sufficient amount of cladding powder into the feeding port; Step 3: Placing the workpiece to be plated in an inert atmosphere for plasma cladding, obtaining a chromium-nickel cladding coating after cooling, and performing cladding residue treatment.

2. A modification method for improving the corrosion resistance of chromium-nickel cladding coating according to claim 1, characterized in that: In step 1, the infiltration sources include Cr and Ni, the modifiers include V and Hf, the activator includes NH4Cl, and the infiltration catalyst includes La2O3; wherein the Cr and Ni powders are sieved through a 1000-mesh sieve.

3. The modification method and modifier composition for improving the corrosion resistance of chromium-nickel cladding coating according to claim 1, characterized in that: In step 1, the solid phase components are weighed by mass percentage, including 30-70% Cr, 15-45% Ni, 2-5% V, 2-5% Hf, 0-5% NH4Cl and 2-5% La2O3.

4. A modification method for improving the corrosion resistance of chromium-nickel cladding coating according to claim 1, characterized in that: In step 1, the cladding powder is obtained by wet grinding the solid phase components in a planetary ball mill and then drying them. The wet grinding medium is anhydrous ethanol, the ball milling speed is 350-400rpm, the time is 12-24h, and the drying conditions are vacuum drying at 80-120℃ for 12-24h.

5. A modification method for improving the corrosion resistance of chromium-nickel cladding coating according to claim 1, characterized in that: In step 3, the plasma cladding process parameters are: cladding current is 80-120A, feed rate is 18-22g / min, scanning rate is 20-40cm / min, nozzle height is 8-12mm, rotation speed is 2-5r / min, ion gas flow rate is 0.2-0.3L / min, shielding gas flow rate is 18-20L / min, and inert gas is Ar or N2.

6. A chromium-nickel cladding coating for improving corrosion resistance, characterized in that: The chromium-nickel cladding coating is prepared according to the modification method for improving the corrosion resistance of the chromium-nickel cladding coating according to any one of claims 1 to 5, and the solid phase components of the chromium-nickel cladding coating are weighed by mass percentage and include 30-70% Cr, 15-45% Ni, 2-5% V, 2-5% Hf, 0-5% NH4Cl and 2-5% La2O3.

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