Chromium-nickel co-permeation coating, and its manufacturing method and use

Abstract

This disclosure provides a chromium-nickel co-impregnation coating, a method for manufacturing the same, and its use. The manufacturing method includes the steps of: surface pre-treating a metal workpiece; shot peening the pre-treated metal workpiece; and applying a chromium-nickel co-impregnation slurry to the surface of the shot-peened metal workpiece in one step, baking it to perform hardening and sintering treatments, thereby obtaining a chromium-nickel co-impregnation coating on the surface of the metal workpiece. The chromium-nickel co-impregnation slurry comprises a solid-phase component and a liquid-phase component, the solid-phase component comprising chromium powder, nickel powder, alumina, and chromium oxide, and the liquid-phase component comprising Al(H2PO4)3, water glass, ammonium iodide, chromium oxide, and magnesium oxide. The coating is suitable for various types of metal workpieces that require surface strengthening, including carbon steel, austenitic stainless steel, and high-temperature alloys, and has a wide range of applications and is extremely practical. Furthermore, the coating has high adhesion and can improve the corrosion resistance and vapor oxidation resistance of metal workpieces at high and low temperatures.

Description

Technical Field

[0001] Cross - reference to Related Applications This application claims priority to a Chinese patent application filed with the China National Intellectual Property Administration on July 19, 2024, with application number 202410975833.3 and invention title "Chromium - Nickel Co - Penetration Coating, and Its Manufacturing Method and Use", the entire content of which is incorporated herein by reference.

[0002] This disclosure belongs to the technical field of material surface coatings, and specifically relates to chromium - nickel co - penetration coatings and their manufacturing methods and uses.

Background Art

[0003] The most commonly used anti - corrosion method for metal workpieces is to coat the surface of the metal with a metal, non - metal, or metal - non - metal composite film as a protective layer through physical, chemical, or electrochemical metal surface treatment processes, thereby preventing or delaying the chemical reaction between the metal and the contacting medium. Related metal surface treatment technologies include thermal spraying, electroplating, thermal diffusion, surface phosphating treatment, metal or non - metal coatings, etc. By constructing a coating on the surface of the workpiece, the components, microstructure, and structure of the material surface are changed, the surface properties are improved, the corrosion resistance and wear resistance of the workpiece are improved, and the service life of the workpiece is extended.

[0004] Among them, the thermal diffusion technology is a process of forming a surface alloy layer by infiltrating metal or non - metal elements to be infiltrated onto the surface of a metal workpiece using heat diffusion. Co - penetration is the most widely used treatment process in thermal diffusion technology, and multiple elements can be simultaneously infiltrated onto the surface of the workpiece by one - time heat diffusion. The emergence of co - penetration integrates the advantages of each unit infiltration, compensates for the disadvantages of unit infiltration through element combination, and enables the surface of the workpiece to have better comprehensive properties.

[0005] Currently, there are various co-opsomnography methods, including those primarily composed of metallic elements, non-metallic elements, and rare earth elements. For example, co-opsomnography of aluminum and chromium into the surface of a high-temperature alloy workpiece forms a dense oxide film called an elemental coating. By utilizing the stable physicochemical properties of this oxide under high-temperature conditions, the service life of the workpiece can be extended. However, most current co-opsomnography of metal workpieces employs solid-state methods, which require the blending of multiple metallic elements with catalysts and other components. This process is time-consuming, requires high experimental requirements, and the resulting coating has low adhesion, is thin, and requires multiple applications to reach the desired thickness, thus limiting its applicability. In particular, in the case of metal workpieces such as high-carbon steel and high-alloy steel, the diffusion rates of Cr, Al, or Fe differ during the elemental diffusion process, resulting in the Kirkendall effect of atomic diffusion. Diffusion of Cr or Al leads to the creation of voids, resulting in numerous pores within the coating. This reduces the density of the coating, increases brittleness, and ultimately causes the coating to peel off. This has a significant impact on performance. Another method involves using alumina, chromium powder, aluminum powder, and ammonium chloride as aluminum-chromium co-impregnation agents. These are placed in a crucible with the chromium-aluminum co-impregnation agent and the component, and heated under an argon atmosphere to obtain a component with an aluminum-chromium coating. This method requires execution in a vacuum environment and strict control of the preparation process. Furthermore, a neutral salt bath chromium-aluminum co-impregnation method is also used, where the co-impregnation agent consists of sodium chloride, barium chloride, sodium fluoride, aluminum powder, and chromium powder. The co-impregnation agent is placed in a crucible, the crucible containing the salt bath chromium-aluminum co-impregnation agent is placed in a resistance furnace and heated, and then the sample is placed in the prepared chromium-aluminum co-impregnation salt bath. The main working surface of the sample is kept as perpendicular as possible to the flow direction of the salt bath, and after 4 hours of heating, the sample is removed and rapidly cooled with oil to produce a chromium-aluminum co-impregnation layer on the surface of the nickel-based high-temperature alloy. This method has a relatively long heating time, many requirements regarding the placement of the sample, and the thickness of the formed coating is relatively thin, only about 20 μm, resulting in poor corrosion resistance and wear resistance. [Overview of the project] [Problems that the invention aims to solve]

[0006] This disclosure aims to solve at least one of the technical problems present in the prior art by providing a chromium-nickel co-permeation coating, a method for manufacturing the same, and its use. [Means for solving the problem]

[0007] In one aspect of this disclosure, A step of performing surface pretreatment on a metal workpiece, The steps include: performing shot peening on a metal workpiece after pretreatment, The process includes the steps of applying a chromium-nickel co-penetration slurry to the surface of a metal workpiece after shot peening, baking it to perform hardening and sintering treatments, and obtaining a chromium-nickel co-penetration coating on the surface of the metal workpiece. The present invention provides a method for producing a chromium-nickel co-impregnation coating, wherein the chromium-nickel co-impregnation slurry comprises a solid phase component and a liquid phase component, the solid phase component comprising chromium powder, nickel powder, alumina, and chromium oxide, and the liquid phase component comprising Al(H2PO4)3, water glass, ammonium iodide, chromium oxide, and magnesium oxide.

[0008] Optionally, the solid-liquid ratio of the solid-phase component to the liquid-phase component is 10:(1~5).

[0009] Optionally, the solid phase component is expressed as a mass percentage. Chromium powder 50-80%, Nickel powder 1-10%, Alumina 10-20%, It contains 0-20% chromium oxide, The sum of the mass percentages of each of the solid phase components listed above is 100%.

[0010] Optionally, chromium powder, nickel powder, alumina, and chromium oxide are ball-milled for 6 to 24 hours at a rotational speed of 350 to 400 rpm to obtain solid phase components.

[0011] Optionally, the liquid phase component is expressed as a mass percentage. Al(H2PO4) 310-30%, Water glass 15-25%, Ammonium iodide 5-10%, Chromium oxide 10-40%, It contains 15-35% magnesium oxide, The sum of the mass percentages of each of the above liquid phase components is 100%.

[0012] Optionally, the coating thickness of the chromium-nickel co-penetrating slurry applied to the surface of the metal workpiece is 0.1 to 1.0 mm.

[0013] Optionally, in the shot peening process, the diameter of the shot peening particles is 0.1 to 1.0 mm, the shot peening pressure is 0.5 to 2.0 MPa, and the shot peening time is 10 to 30 minutes.

[0014] Optionally, the step of baking a metal workpiece coated with a chromium-nickel co-impregnation slurry to perform hardening and sintering treatments is: The metal workpiece coated with chromium-nickel co-impregnation slurry is pre-baked at 60-85°C for 5-30 minutes, then baked at 100-160°C for 30-60 minutes, and finally cured at 250-300°C for 20-60 minutes. This includes sintering the baked metal workpiece at 500-650°C for 5-30 minutes.

[0015] Another aspect of this disclosure proposes a chromium-nickel co-penetration coating produced by the manufacturing method described above.

[0016] In another aspect of the present disclosure, there is proposed the use of a chromium-nickel co-permeation coating, wherein the aforementioned chromium-nickel co-permeation coating is used on the surface of metal workpieces of carbon steel, austenitic steel, and superalloys.

Advantages of the Invention

[0017] The present disclosure provides a chromium-nickel co-permeation coating, its manufacturing method, and its use. The manufacturing method includes the steps of performing surface pretreatment on a metal workpiece, performing shot peening treatment on the pretreated metal workpiece, uniformly applying a chromium-nickel co-permeation slurry to the surface of the metal workpiece after the shot peening treatment, baking to perform a curing treatment and a sintering treatment to obtain a chromium-nickel co-permeation coating on the surface of the metal workpiece. The chromium-nickel co-permeation slurry includes a solid-phase component and a liquid-phase component. The solid-phase component includes chromium powder, nickel powder, alumina, and chromium oxide. The liquid-phase component includes Al(H2PO4)3, water glass, ammonium iodide, chromium oxide, and magnesium oxide. The coating is suitable for various types of metal workpieces that need to strengthen the surface, including workpieces such as carbon steel, austenitic stainless steel, and superalloys. It has a wide application range, extremely high practicality. Also, this coating has high adhesion and can further improve the corrosion resistance and steam oxidation resistance of the metal workpiece at high and low temperatures.

Brief Description of the Drawings

[0018] [Figure 1] It is a flowchart of the manufacturing method of the chromium-nickel co-permeation coating according to an embodiment of the present disclosure. [Figure 2] It is an electron microscope image of the chromium-nickel co-permeation coating manufactured in Example 3 of the present disclosure.

Modes for Carrying Out the Invention

[0019] To better enable those skilled in the art to understand the technical solutions of this disclosure, the disclosure will be described in further detail below with reference to the drawings and specific embodiments. Clearly, the embodiments described are some, but not all, embodiments of the present invention. All other embodiments that those skilled in the art can derive from the embodiments described in this disclosure without requiring any creative work are all within the scope of this disclosure.

[0020] As shown in Figure 1, one aspect of the present disclosure provides a method S100 for manufacturing a chromium-nickel co-penetration coating, which specifically includes the following steps S110 to S130.

[0021] S110: Surface pretreatment is performed on the metal workpiece. Specifically, oil stains and dust on the surface of the metal workpiece can be cleaned using organic reagents such as alcohol or acetone, and oxide scale on the surface of the metal workpiece can be removed using a steel brush, sandpaper, or polishing.

[0022] In this embodiment, the material and type of the metal workpiece are not particularly limited. For example, it may be a high-temperature alloy metal workpiece, various carbon steel metal workpieces, or austenitic steel metal workpieces. Of course, such a metal workpiece may be a pipe workpiece, a turbine blade in the aerospace field, or any other type of workpiece.

[0023] S120: Shot peening treatment is performed on the metal workpiece after pretreatment. Specifically, in the shot peening process, shot peening particles are sprayed at high speed onto the surface of a metal workpiece, causing plastic deformation of the surface layer and forming a reinforced layer of a certain thickness. Here, the diameter of the shot peening particles is 0.1 to 1.0 mm, the shot peening pressure is 0.5 to 2.0 MPa, and the shot peening time is 10 to 30 minutes.

[0024] In this embodiment, by activating the surface of the metal workpiece, the physical properties and adhesive strength of the metal workpiece, such as surface adhesion, roughness, and specific surface area, are improved. This is advantageous because it improves the adhesion of the subsequent penetrating coating, further enhances the penetration effect of the subsequent co-penetrating coating, and allows for a thicker coating.

[0025] S130: A chromium-nickel co-penetrating slurry is applied to the surface of a metal workpiece after shot peening, and then baked to perform hardening and sintering treatments to obtain a chromium-nickel co-penetrating coating on the surface of the metal workpiece.

[0026] It should be explained that in this embodiment, the method of applying the chromium-nickel co-impregnation slurry to the surface of the metal workpiece is not particularly limited, and the chromium-nickel co-impregnation slurry may be applied to the surface of the metal workpiece by methods such as spray coating or palm brushing.

[0027] Furthermore, it should be explained that currently manufactured chromium-aluminum co-penetration coatings are relatively thin, and multiple applications are required to increase the coating thickness, resulting in poor stability. In contrast, in this embodiment, the required thickness can be achieved with only one application, without the need for multiple applications, and the thickness of this coating can be adjusted according to actual needs.

[0028] Specifically, in the coating process of this embodiment, it is not necessary to apply the coating layer by layer in multiple steps, but rather to apply the chromium-nickel co-impregnation slurry all at once to an appropriate thickness, where the coating thickness of the chromium-nickel co-impregnation slurry is 0.1 to 1.0 mm. In other words, in this embodiment, the chromium-nickel co-impregnation slurry is applied all at once to the surface of the metal workpiece to form a single layer of chromium-nickel co-impregnation coating, and the thickness of this single layer of chromium-nickel co-impregnation coating is 0.1 to 1.0 mm. Within this thickness range, not only can the applicability of the metal workpiece itself be ensured, but the high-temperature corrosion resistance of the metal workpiece can also be improved.

[0029] In some arbitrary embodiments, the slurry coating thickness of the chromium-nickel co-penetration coating is 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, etc.

[0030] It is understood that the lifespan of a coating is related not only to the thickness of the coating but also to the material of the coating itself and its bonding strength to the matrix. Most current coatings are chromium-aluminum coatings, which are made by mixing chromium powder, aluminum powder, and some chloride powder together, and obtaining a co-impregnating agent through complex pretreatment processes such as crushing, calcination, and cooling, and then applying it to the surface of the workpiece. Since the co-impregnating agent is composed entirely of powder, this method involves a complex co-impregnating agent processing process, and the bonding strength between the coating and the workpiece is weak, making the coating prone to peeling. In contrast, the chromium-nickel co-impregnating slurry of this embodiment contains not only solid-phase components but also liquid-phase components to reduce the pretreatment process of the co-impregnating agent.

[0031] Specifically, the chromium-nickel co-impregnation slurry contains solid-phase and liquid-phase components. The solid-phase components include chromium powder, nickel powder, alumina, and chromium oxide, while the liquid-phase components include Al(H2PO4)3, water glass, ammonium iodide, chromium oxide, and magnesium oxide.

[0032] In this embodiment, mixing the liquid phase component and the solid phase component improves the adhesion between the chromium-nickel co-impregnation slurry and the workpiece, prevents the coating from peeling off, and simplifies the slurry preparation process by eliminating the need for complex pretreatment steps for the solid phase component.

[0033] In some other arbitrary embodiments, the solid-to-liquid ratio (g:mL) of the solid-phase component to the liquid-phase component is 10:(1~5).

[0034] In some other optional embodiments, the liquid phase component comprises, by mass percentage, 10-30% Al(H2PO4)3, 15-25% water glass, 5-10% ammonium iodide, 10-40% chromium oxide, and 15-35% magnesium oxide.

[0035] In this solution, Al(H2PO4)3 and water glass are used as binders in the liquid phase, resulting in high adhesive strength with the metal matrix and enabling the required coating thickness to be achieved in a single application. Furthermore, during the baking process of the slurry, Al(H2PO4)3 and water glass can decompose directly without generating harmful gases, thus avoiding the formation of bubbles within the coating and resulting in a dense, bubble-free coating structure. In addition, the above binder components have good high-temperature toughness and are less prone to cracking during the baking process.

[0036] Furthermore, in the liquid phase component, ammonium iodide is used as a penetration aid, forming an active transition halide gas that can accelerate the penetration rate of active chromium and nickel atoms into the matrix.

[0037] Furthermore, in the liquid phase component, magnesium oxide acts as a curing agent, effectively lowering the curing temperature of the slurry by dehydrating and polycondensing the acidic phosphoric acid in the binder. Additionally, by adding an appropriate amount of chromium oxide, the curing reaction rate between magnesium oxide and the binder is reduced, preventing problems such as cracking on the surface of the cured coating and failure to form a coating film due to excessively fast curing.

[0038] Possible forms include: Al(H2PO4)3 content is preferably 10%, 15%, 20%, 25%, or 30%; water glass content is preferably 15%, 20%, or 25%; ammonium iodide content is preferably 5%, 7%, or 10%; chromium oxide content is preferably 10%, 15%, 20%, 28%, 35%, or 40%; and magnesium oxide content is preferably 15%, 25%, 30%, or 35%.

[0039] In some other arbitrary embodiments, the solid phase component comprises, by mass percentage, 50-80% chromium powder, 1-10% nickel powder, 10-20% alumina, and 0-20% chromium oxide.

[0040] In this solid-phase configuration, alumina and chromium oxide are used as fillers, effectively preventing uneven penetration of the chromium and nickel powders, and between the chromium and nickel powders and the matrix, during the slurry preparation process. Furthermore, adding a small amount of nickel can accelerate the chromizing rate, lower the chromizing temperature, and achieve the required chromizing layer thickness while mitigating the adverse effects of heat treatment on the overall mechanical properties of the matrix.

[0041] It should be noted that in this embodiment, the chromium and nickel elements are each impregnated into the matrix metal, and the chromium and nickel that have penetrated the matrix can also form intermetallic compounds with the matrix. Compared to a single chromizing coating, the chromium-nickel co-impregnation layer has superior wear resistance and corrosion resistance.

[0042] Possible forms include a chromium powder content of preferably 50%, 60%, 70%, or 80%, a nickel powder content of preferably 1%, 5%, or 10%, an alumina content of preferably 10%, 15%, or 20%, and a chromium oxide content of preferably 1%, 5%, 12%, 15%, or 20%.

[0043] In some other arbitrary embodiments, chromium powder, nickel powder, alumina, and chromium oxide are ball-milled in a star ball milling tank to obtain solid phase components. Here, the rotational speed of the ball milling process is 350-400 rpm, and the ball milling time is 6-24 hours. Each mixed metal powder is ball-milled and then mixed with the liquid phase components, which is advantageous for uniformly mixing each component.

[0044] Furthermore, the step of baking the metal workpiece coated with chromium-nickel co-impregnation slurry to perform hardening and sintering treatments is, specifically, The metal workpiece coated with chromium-nickel co-impregnation slurry is pre-baked at a low temperature of 60-85°C for 5-30 minutes, then baked at a low temperature of 100-160°C for 30-60 minutes, and finally cured at a medium temperature of 250-300°C for 20-60 minutes. The process includes the step of sintering the baked metal workpiece at 500-650°C for 5-30 minutes.

[0045] In some arbitrary embodiments, the low-temperature pre-bake temperature is preferably 60°C, 70°C, or 80°C, and the duration is preferably 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, or 30 minutes.

[0046] In some other optional embodiments, the low-temperature bake temperature is preferably 100°C, 120°C, 140°C, 150°C, or 160°C, and the time is preferably 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, or 60 minutes.

[0047] In some other optional embodiments, the intermediate curing temperature is preferably 250°C, 260°C, 270°C, 280°C, 290°C, or 300°C, and the curing time is preferably 20 minutes, 30 minutes, 40 minutes, 50 minutes, or 60 minutes.

[0048] In some other arbitrary embodiments, the sintering temperature is preferably 500°C, 550°C, 600°C, or 650°C, and the sintering time is preferably 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, or 30 minutes.

[0049] In this embodiment, by employing a stepwise gradient curing process, it is advantageous to ensure that the co-permeating slurry does not develop surface quality problems due to localized stress during the curing process, while also improving the adhesion of the co-permeating slurry, enhancing the coating effect, shortening the curing time, and reducing energy consumption.

[0050] The manufacturing method for the chromium-nickel co-impregnation coating of this embodiment is simple, does not require vacuum conditions, has high production efficiency, and produces minimal contamination during the production process. The chromium-nickel co-impregnation coating formed based on the above components has good bonding properties with the matrix, effectively preventing the coating from peeling off during use, thereby achieving the objective of extending the coating's lifespan. Furthermore, this chromium-nickel co-impregnation coating has a wide range of applications and high practicality, and is suitable not only for high-temperature alloys but also for other metal workpieces such as various carbon steels and austenitic steels.

[0051] Another aspect of this disclosure proposes a chromium-nickel co-penetration coating produced by the manufacturing method described above.

[0052] In this embodiment, the thickness of the chromium-nickel co-penetration coating formed on various metal workpieces is 5 to 50 μm. Coatings of this thickness exhibit good bonding strength to the surface of the metal workpiece, as well as excellent corrosion resistance and vapor oxidation resistance at high and low temperatures.

[0053] Another aspect of the present disclosure is the use of a chromium-nickel co-penetration coating, wherein the aforementioned chromium-nickel co-penetration coating is used on the surface of a metal workpiece made of carbon steel, austenitic steel, and high-temperature alloy.

[0054] The method for manufacturing chromium-nickel co-permeation coatings will be further described below with reference to several specific examples. [Examples]

[0055] In this embodiment, the metal workpiece to be processed was the piping of a large boiler made of carbon steel. The specifications of the piping were all 55 mm outer diameter, 8 mm wall thickness, and 4000 mm length. The process of applying chromium-nickel penetration treatment to the surface of the metal workpiece includes the following steps.

[0056] S1: Cleaning the surface of the pipes The surface of the piping workpiece was cleaned of oil stains and dust using alcohol / acetone, and the oxide scale on the surface was removed using a steel brush.

[0057] S2: Surface shot peening treatment The piping workpieces after cleaning were subjected to shot peening, with a shot peening particle diameter of 0.3 mm, a shot peening pressure of 0.5 MPa, and a shot peening time of 10 minutes.

[0058] S3: Application of slurry to the surface The chromium-nickel co-penetrating slurry should be applied in a single coat to a thickness of 0.5 mm using a spray coating method (a palm brush or other method may also be employed), and should not be applied in multiple layers.

[0059] The method for producing the chromium-nickel co-impregnation slurry is as follows: As a solid phase component, 70% chromium powder, 5% nickel powder, 15% alumina, and 10% chromium oxide were weighed by mass percentage and mixed. The resulting metal mixture powder was ball milled at a ball milling speed of 350 rpm for 8 hours to obtain the final solid phase component. As a liquid phase component, 25% Al(H2PO4)3, 18% water glass, 7% ammonium iodide, 15% chromium oxide, and 35% magnesium oxide were weighed by mass percentage, mixed, and stirred to obtain the liquid phase component. The solid phase component and the liquid phase component were mixed in a solid-liquid (g:ml) ratio of 10:2 to obtain the final metal powder coating raw material.

[0060] S4: Bake curing A stepwise gradient curing process is employed, in which the metal piping workpiece coated with chromium-nickel impregnating material is pre-baked at 75°C for 5 minutes, then baked at 140°C for 55 minutes, and finally cured at 250°C for 30 minutes.

[0061] S5: High-speed sintering A metal pipe workpiece was rapidly sintered using a high-speed heating method to diffuse and penetrate chromium, and then air-cooled to room temperature. Here, the heating rate was 1000°C / min, the holding temperature was 500°C, and the holding time was 30 minutes. A chromium-nickel co-penetration coating was obtained on the metal pipe workpiece.

[0062] In Example 1, the obtained chromium-nickel co-permeation coating was subjected to an oxidation test. Specifically, after repeated oxidation at 500°C for 100 hours, the weight increase due to oxidation of the manufactured chromium-nickel co-permeation coating sample was 0.15 mg / mm³. 2 The weight increase due to oxidation of the carbon steel matrix was 1.47 mg / mm³. 2 As a result, the oxidation rate decreased by 89.8%.

[0063] In this Example 1, the obtained chromium-nickel co-impregnation coating was subjected to a wear resistance test. Specifically, under test conditions of a load of 10g and a load holding time of 10 seconds, the microhardness of the manufactured chromium-nickel co-impregnation coating was approximately 412HV, while the microhardness of the carbon steel matrix was approximately 320HV, indicating an improvement of about 1.3 times in hardness. Furthermore, in this Example 1, the wear resistance of the carbon steel and the coating was tested according to the international GB / T 12444-2006 "Methods for testing wear of metallic materials." Under the same test conditions, the frictional wear amount of the coating sample decreased by approximately 21.7%, and the coefficient of friction decreased by approximately 6.8%. [Examples]

[0064] In this embodiment, the metal workpiece to be treated was the piping of a large boiler made of austenitic steel. The specifications of the piping were all 55 mm outer diameter, 8 mm wall thickness, and 4000 mm length. The process of applying chromium-nickel penetration treatment to the surface of the metal piping workpiece includes the following steps.

[0065] S1: Cleaning the surface of the pipes The surface of the piping workpiece was cleaned of oil stains and dust using alcohol / acetone, and the oxide scale on the surface was removed using a steel brush.

[0066] S2: Surface shot peening treatment The piping workpieces after cleaning were subjected to shot peening, with a shot peening particle diameter of 0.5 mm, a shot peening pressure of 1.0 MPa, and a shot peening time of 10 minutes.

[0067] S3: Application of slurry to the surface The chromium-nickel co-penetrating slurry should be applied in a single coat to a thickness of 0.5 mm using a spray coating method (a palm brush or other method may also be employed), and should not be applied in multiple layers.

[0068] The method for producing the chromium-nickel co-impregnation slurry is as follows: As the solid phase component, 75% chromium powder, 3% nickel powder, 10% alumina, and 12% chromium oxide were weighed and mixed. The resulting metal powder mixture was ball milled at a ball milling speed of 350 rpm for 10 hours to obtain the final solid phase component. As the liquid phase component, 30% Al(H2PO4)3, 25% water glass, 10% ammonium iodide, 20% chromium oxide, and 15% magnesium oxide were weighed by mass percentage, mixed, and stirred to obtain the liquid phase component. The solid phase component and the liquid phase component were mixed in a solid-liquid (g:ml) ratio of 10:3 to obtain the final metal powder coating raw material.

[0069] S4: Bake curing A stepwise gradient curing process is employed, in which the metal piping workpiece coated with chromium-nickel impregnating material is pre-baked at 85°C for 5 minutes, then baked at 160°C for 55 minutes, and finally cured at 300°C for 30 minutes.

[0070] S5: High-speed sintering A metal pipe workpiece was rapidly sintered using a high-speed heating method to diffuse and penetrate chromium, and then air-cooled to room temperature. Here, the heating rate was 1000°C / min, the holding temperature was 550°C, and the holding time was 30 minutes. A chromium-nickel co-penetration coating was obtained on the metal pipe workpiece.

[0071] In Example 2, the obtained chromium-nickel co-permeation coating was subjected to an oxidation test. Specifically, after repeated oxidation at 650°C for 100 hours, the weight increase due to oxidation of the manufactured chromium-nickel co-permeation coating sample was 0.000078 mg / mm³. 2 The weight increase due to oxidation of the stainless steel matrix is ​​0.0047 mg / mm³. 2 As a result, the oxidation rate decreased by 98.3%.

[0072] In this second example, the obtained chromium-nickel co-impregnation coating was subjected to abrasion resistance testing. Specifically, under test conditions of a load of 10g and a load holding time of 10s, the microhardness of the manufactured chromium-nickel co-impregnation coating was approximately 400HV, while the microhardness of the austenitic steel matrix was approximately 190HV, indicating an improvement of about 2.1 times in hardness. Furthermore, in this second example, the abrasion resistance of the austenitic steel and the coating was tested according to the international GB / T 12444-2006 "Test Methods for Abrasion of Metallic Materials." Under the same test conditions, the frictional wear amount of the coating sample decreased by approximately 39%, and the coefficient of friction decreased by approximately 13%. [Examples]

[0073] In this embodiment, the metal workpiece to be processed was piping from a large boiler made of a high-temperature alloy material. The specifications of the piping were all 55 mm outer diameter, 8 mm wall thickness, and 4000 mm length. The process of applying chromium-nickel penetration treatment to the surface of the metal piping workpiece includes the following steps.

[0074] S1: Cleaning the surface of the pipes The surface of the piping workpiece was cleaned of oil stains and dust using alcohol / acetone, and the oxide scale on the surface was removed using a steel brush.

[0075] S2: Surface shot peening treatment The piping workpieces after cleaning were subjected to shot peening, with a shot peening particle diameter of 0.5 mm, a shot peening pressure of 1.5 MPa, and a shot peening time of 15 minutes.

[0076] S3: Application of slurry to the surface The chromium-nickel co-penetrating slurry should be applied in a single coat to a thickness of 1.0 mm using a spray coating method (a palm brush or other method may also be employed), and should not be applied in multiple layers.

[0077] The method for producing the chromium-nickel co-impregnation slurry is as follows: As solid-phase components, 60% chromium powder, 5% nickel powder, 20% alumina, and 15% chromium oxide were weighed by mass percentage and mixed. The resulting metal powder mixture was ball-milled at a ball milling speed of 350 rpm for 12 hours to obtain the final solid-phase components. As liquid-phase components, 25% Al(H2PO4)3, 20% water glass, 5% ammonium iodide, 35% chromium oxide, and 15% magnesium oxide were weighed by mass percentage, mixed, and stirred to obtain the liquid-phase components. The solid-phase components and liquid-phase components were mixed in a solid-liquid (g:ml) ratio of 10:5 to obtain the final metal powder coating raw material.

[0078] S4: Bake curing A stepwise gradient curing process is employed, in which the metal piping workpiece coated with chromium-nickel impregnating material is pre-baked at 80°C for 10 minutes, then baked at 150°C for 30 minutes, and finally cured at 300°C for 20 minutes.

[0079] S5: High-speed sintering A metal pipe workpiece was rapidly sintered using a high-speed heating method to diffuse and penetrate chromium, and then air-cooled to room temperature. Here, the heating rate was 1000°C / min, the holding temperature was 650°C, and the holding time was 20 minutes. A chromium-nickel co-penetration coating was obtained on the metal pipe workpiece.

[0080] In Example 3, the obtained chromium-nickel co-permeation coating was subjected to an oxidation test. Specifically, after repeated oxidation at 1000°C for 100 hours, the weight increase due to oxidation of the manufactured chromium-nickel co-permeation coating sample was 0.012 mg / mm³. 2 The weight increase due to oxidation of the high-temperature alloy matrix is ​​0.108 mg / mm³. 2 As a result, the oxidation rate decreased by 88.9%.

[0081] In this third example, the obtained chromium-nickel co-impregnation coating was subjected to abrasion resistance testing. Specifically, the microhardness of the manufactured chromium-nickel co-impregnation coating was approximately 437 HV, while the microhardness of the high-temperature alloy matrix was approximately 300 HV, indicating an improvement of about 1.5 times in hardness. Furthermore, in this third example, the abrasion resistance of the high-temperature alloy and coating was tested according to the international GB / T 12444-2006 "Test Methods for Abrasion of Metallic Materials." Under the same test conditions, the frictional wear of the coating sample decreased by approximately 20.3%, and the coefficient of friction decreased by approximately 6.8%.

[0082] As shown in Figure 2, the chromium-nickel co-penetration coating obtained in this Example 3 had a thickness of approximately 31 μm, with average chromium and nickel content of 35 wt.% and 6 wt.%, respectively. The co-penetration coating had a uniform and dense structure, no obvious internal defects, and good metallurgical bonding with the matrix. [Examples]

[0083] In this example, the metal workpiece to be processed was the piping of a large boiler made of high-temperature alloy material. The specifications of this piping were all 55 mm outer diameter, 8 mm wall thickness, and 4000 mm length. The process of applying chromium-nickel penetration treatment to the surface of this metal workpiece includes the following steps.

[0084] S1: Cleaning the surface of the pipes The surface of the piping workpiece was cleaned of oil stains and dust using alcohol / acetone, and the oxide scale on the surface was removed using a steel brush.

[0085] S2: Surface shot peening treatment The piping workpieces after cleaning were subjected to shot peening, with a shot peening particle diameter of 0.1 mm, a shot peening pressure of 1.0 MPa, and a shot peening time of 20 minutes.

[0086] S3: Application of slurry to the surface The chromium-nickel co-penetrating slurry should be applied in a single coat to a thickness of 0.8 mm using a spray coating method (a palm brush or other method may also be employed), and should not be applied in multiple layers.

[0087] The method for producing the chromium-nickel co-impregnation slurry is as follows: As a solid phase component, 70% chromium powder, 5% nickel powder, 10% alumina, and 15% chromium oxide were weighed by mass percentage and mixed. The resulting metal powder mixture was ball milled at a ball milling speed of 400 rpm for 24 hours to obtain the final solid phase component. As a liquid phase component, 20% Al(H2PO4)3, 15% water glass, 7% ammonium iodide, 28% chromium oxide, and 30% magnesium oxide were weighed by mass percentage, mixed, and stirred to obtain the liquid phase component. The solid phase component and the liquid phase component were mixed in a solid-liquid (g:ml) ratio of 10:5 to obtain the final metal powder coating raw material.

[0088] S4: Bake curing A stepwise gradient curing process is employed, in which the metal piping workpiece coated with chromium-nickel impregnating material is pre-baked at 60°C for 5 minutes, then baked at 100°C for 55 minutes, and finally cured at 250°C for 30 minutes.

[0089] S5: High-speed sintering A metal pipe workpiece was rapidly sintered using a high-speed heating method to diffuse and penetrate chromium, and then air-cooled to room temperature. Here, the heating rate was 1000°C / min, the holding temperature was 500°C, and the holding time was 30 minutes. A chromium-nickel co-penetration coating was obtained on the metal pipe workpiece.

[0090] In Example 4, the obtained chromium-nickel co-permeation coating was subjected to an oxidation test. Specifically, after repeated oxidation at 1000°C for 100 hours, the weight increase due to oxidation of the manufactured chromium-nickel co-permeation coating sample was 0.033 mg / mm³. 2 The weight increase due to oxidation of the high-temperature alloy matrix is ​​0.108 mg / mm³. 2 As a result, the oxidation rate decreased by 69.4%.

[0091] In this Example 4, the obtained chromium-nickel co-impregnation coating was subjected to abrasion resistance testing. Specifically, the microhardness of the manufactured chromium-nickel co-impregnation coating was approximately 419.6 HV, while the microhardness of the high-temperature alloy matrix was approximately 300 HV, indicating an improvement of about 1.4 times in hardness. Furthermore, in this Example 4, the abrasion resistance of the high-temperature alloy and coating was tested according to the international GB / T 12444-2006 "Test Methods for Abrasion of Metallic Materials." Under the same test conditions, the frictional wear of the coating sample decreased by approximately 18.3%, and the coefficient of friction decreased by approximately 6.2%.

[0092] This disclosure proposes a chromium-nickel co-permeation coating, its manufacturing method, and its use, which has the following beneficial effects compared to the prior art.

[0093] Firstly, the chromium-nickel high-temperature corrosion-resistant coating and its manufacturing method according to this disclosure do not require vacuum conditions and have a simple manufacturing process. Furthermore, the chromium-nickel co-penetration coating has high manufacturing efficiency, low contamination, adjustable thickness, good wear resistance, and particularly excellent corrosion resistance and vapor oxidation resistance at high and low temperatures.

[0094] Secondly, this disclosure provides a chromium-nickel co-impregnation slurry formed by mixing a solid-phase component with a liquid-phase component, which readily coats the surface of a metal workpiece and has a strong bonding force with the workpiece surface.

[0095] Thirdly, the metal powder raw materials described herein are suitable for a wide range of metal workpieces that require surface strengthening, such as carbon steel, austenitic stainless steel, and high-temperature alloy workpieces, and are highly practical and widely applicable.

[0096] Fourthly, the present disclosure applies a shot peening treatment prior to co-penetration coating to increase the specific surface area of ​​the metal workpiece, improve the penetration of metal elements and the adhesion of the coating, thereby further improving the strength and corrosion resistance of the surface coating.

[0097] The embodiments described above are merely illustrative examples for illustrating the principles of the Disclosure, but the Disclosure is not limited thereto. Those skilled in the art can make various modifications and improvements without departing from the spirit and essence of the Disclosure, and such modifications and improvements will also be considered within the scope of the Disclosure.

Claims

1. A method for manufacturing a chromium-nickel co-permeation coating, A step of performing surface pretreatment on a metal workpiece, The steps include: performing shot peening on a metal workpiece after pretreatment, The process includes the steps of applying a chromium-nickel co-penetration slurry to the surface of a metal workpiece after shot peening, baking it to perform hardening and sintering treatments, and obtaining a chromium-nickel co-penetration coating on the surface of the metal workpiece. The chromium-nickel co-permeation slurry comprises a solid phase component and a liquid phase component, the solid phase component comprising chromium powder, nickel powder, alumina, and chromium oxide, and the liquid phase component comprising Al(H) ２ PO ４ ) ３ A method for producing a chromium-nickel co-permeation coating, characterized by comprising water glass, ammonium iodide, chromium oxide, and magnesium oxide.

2. The manufacturing method according to claim 1, characterized in that the solid-liquid ratio of the solid-phase component to the liquid-phase component is 10:(1 to 5).

3. The solid phase component is, by mass percentage, 50-80% chromium powder, Nickel powder 1-10% and Alumina 10-20%, It contains 0-20% chromium oxide, The manufacturing method according to claim 1, characterized in that the sum of the mass percentages of each of the above solid phase components is 100%.

4. The manufacturing method according to claim 3, characterized in that the chromium powder, nickel powder, alumina, and chromium oxide are ball-milled for 6 to 24 hours at a rotational speed of 350 to 400 rpm to obtain a solid phase component.

5. The aforementioned liquid phase component is, by mass percentage, 2(2) ２ PO ４ ) ) ３ 100%と、 Water glass 15-25%, Ammonium iodide 5-10%, Chromium oxide 10-40%, It contains 15-35% magnesium oxide, The manufacturing method according to claim 1, characterized in that the sum of the mass percentages of each of the above liquid phase components is 100%.

6. The manufacturing method according to any one of claims 1 to 5, characterized in that the coating thickness of the chromium-nickel co-penetrating slurry applied to the surface of the metal workpiece is 0.1 to 1.0 mm.

7. A manufacturing method according to any one of claims 1 to 5, characterized in that, in the shot peening process, the diameter of the shot peening particles is 0.1 to 1.0 mm, the shot peening pressure is 0.5 to 2.0 MPa, and the shot peening time is 10 to 30 minutes.

8. The step of baking a metal workpiece coated with a chromium-nickel co-impregnation slurry to perform hardening and sintering treatments is: The metal workpiece coated with chromium-nickel co-penetration slurry is pre-baked at 60-85°C for 5-30 minutes, then baked at 100-160°C for 30-60 minutes, and finally cured at 250-300°C for 20-60 minutes. A manufacturing method according to any one of claims 1 to 5, characterized by comprising sintering the bake-hardened metal workpiece at 500 to 650°C for 5 to 30 minutes.

9. Chromium-nickel co-penetration coating, A chromium-nickel co-penetrating coating characterized by being manufactured by the manufacturing method described in any one of claims 1 to 8.

10. The use of chromium-nickel co-penetration coating, The chromium-nickel co-penetration coating according to claim 9 is characterized by being used on the surface of a metal workpiece made of carbon steel, austenitic steel, or a high-temperature alloy.

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