A method for corrosion protection of reactive metals and reactive metals

Abstract

This application belongs to the field of corrosion protection technology, specifically relating to a method for corrosion protection of active metals and the active metal itself. The method includes: under a protective atmosphere, controlling a cemented carbide ball to slide along the surface of the active metal to be treated, performing dynamic surface extrusion treatment; the contact surface between the cemented carbide ball and the active metal undergoes plastic deformation under high strain and high strain rate, obtaining a nanocrystalline structure. This method, without introducing impurity elements, prepares a gradient nanostructure from the surface to the interior of a cerium-gallium alloy surface, utilizing small-angle grain boundaries to generate a dense oxide film, thereby achieving the purpose of improving the room-temperature oxidation resistance of the active metal for corrosion protection.

Description

Technical Field

[0001] This application belongs to the field of corrosion protection technology, specifically relating to a corrosion protection method for active metals and active metals. Background Technology

[0002] Reactive metals, such as cerium-gallium alloys, are highly susceptible to oxidation and corrosion. This is because reactive metals are extremely sensitive to atmosphere. Although they can form a certain thickness of oxide film under dry air conditions, similar to metals like titanium, aluminum, and zinc, this oxide film is insufficient to prevent the continuous diffusion of oxygen atoms, leading to ongoing oxidation. Furthermore, significant differences in density and crystal structure between the oxide and the substrate can cause the oxide film to easily break down, exposing fresh metal and accelerating oxidation.

[0003] Currently, the most common corrosion protection technology is to electroplate a pure nickel coating onto the surface of a reactive metal. This technology typically requires a coating several millimeters thick on the reactive metal surface. Its drawback is that the electroplated coating density is insufficient; without reaching a certain thickness, it is difficult to effectively inhibit room temperature oxidation corrosion. The electroplated coating, only a few millimeters thick, reduces the purity of the reactive metal, essentially introducing difficult-to-remove impurities into it. Summary of the Invention

[0004] The purpose of this application is to provide a method for preventing corrosion of reactive metals and a reactive metal, which solves the problem in the prior art where an electroplating coating several millimeters thick reduces the purity of the reactive metal, which is equivalent to introducing impurities that are difficult to remove into the reactive metal.

[0005] The technical solution to achieve the purpose of this application is as follows:

[0006] The first aspect of this application provides a method for corrosion protection of reactive metals, the method comprising:

[0007] Under a protective atmosphere, a cemented carbide ball is controlled to slide along the surface of the active metal to be treated, and a dynamic extrusion treatment is performed on the surface. The contact surface between the cemented carbide ball and the active metal undergoes plastic deformation under high strain and high strain rate to obtain a nanocrystalline structure.

[0008] Optionally, the control of the carbide ball to slide along the surface of the active metal to be treated further includes:

[0009] The active metal is forged into a round bar by rotary forging.

[0010] The round bar is horizontally loaded onto the surface dynamic extrusion device, with both ends of the round bar pressed together.

[0011] Optionally, controlling the carbide ball to slide along the surface of the active metal to be treated specifically includes:

[0012] A surface dynamic extrusion process with a rotation speed of 300 r / min, a feed rate of 0.01 mm / r, and a single pass pressing depth of 20 μm is used to control the sliding of the cemented carbide ball along the surface of the active metal.

[0013] Optionally, controlling the carbide ball to slide along the surface of the active metal to be treated specifically includes:

[0014] Lubricating oil is used for cooling during the sliding process.

[0015] Optionally, the control of the cemented carbide ball to slide along the surface of the active metal further includes:

[0016] The processed round bar was cut into 10mm×10mm×10mm samples using a wire cutting device.

[0017] Optionally, the protective atmosphere is a liquid nitrogen protective atmosphere.

[0018] Optionally, the cemented carbide ball is made of WC-Co alloy.

[0019] Optionally, the active metal is a cerium-gallium alloy.

[0020] The second aspect of this application provides a reactive metal, which is obtained using any one of the reactive metal corrosion prevention methods provided in the first aspect of this application.

[0021] The beneficial technical effects of this application are as follows:

[0022] This application provides a method for corrosion protection of active metals and the active metal itself. The aim is to improve the corrosion resistance of active metals to room temperature oxidation by preparing a gradient nanostructure from the surface to the interior of a cerium-gallium alloy surface without introducing impurity elements. This is achieved by utilizing small-angle grain boundaries to generate a dense oxide film. The introduction of small-angle grain boundaries makes the surface denser, forming a more dense oxide film compared to untreated coarse grains. This inhibits oxygen diffusion and enhances the room temperature oxidation corrosion resistance of the cerium-gallium alloy. Attached Figure Description

[0023] Figure 1 A schematic flowchart illustrating a method for corrosion protection of reactive metals provided in this application embodiment;

[0024] Figure 2 This is a schematic diagram of the coarse-grained structure of an untreated cerium-gallium alloy;

[0025] Figure 3 This is a schematic diagram of the surface dynamic extrusion treatment technology in a method for corrosion protection of reactive metals provided in this application embodiment;

[0026] Figure 4This is a schematic diagram of surface plastic deformation during the dynamic extrusion treatment process in a method for preventing corrosion of active metals provided in this application embodiment;

[0027] Figure 5 a-5c shows the cross-sectional morphology of the cerium-gallium surface layer deformation structure after surface dynamic extrusion treatment in an active metal anti-corrosion method provided in this application embodiment;

[0028] Figure 6 The oxidation kinetics curves of coarse-grained and nano-crystalline cerium-gallium alloys under room temperature oxidizing atmosphere after surface dynamic extrusion treatment are provided in an embodiment of this application for corrosion protection of active metals.

[0029] In the picture:

[0030] 1-Active metal; 2-Hard alloy ball; 3-Lubricating oil; 4-Active metal surface; 5-Nanocrystalline structure. Detailed Implementation

[0031] To enable those skilled in the art to better understand this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only a part of the embodiments of this application, and not all of them. Based on the embodiments described in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0032] To address the problems of existing technologies, the inventors of this application discovered that surface dynamic extrusion processing of cerium-gallium alloys does not require the introduction of impurity elements. This process transforms the surface grain boundaries into small-angle grain boundaries at the nanoscale, forming a continuous atomic arrangement. The newly formed oxide film is also nanoscale, exhibiting a higher density and less difference from the substrate compared to conventional oxide films, effectively mitigating oxide film cracking. By introducing grain boundary engineering techniques to redesign the grain boundary structure and lattice type of the special material, it can spontaneously form a new, dense oxide film, significantly reducing the oxygen diffusion rate within the oxide film and thus effectively improving the corrosion resistance of cerium-gallium alloys.

[0033] Based on the above, in order to clearly and in detail illustrate the advantages of this application, the specific embodiments of this application will be described below in conjunction with the accompanying drawings.

[0034] See Figure 1 The figure is a schematic flowchart of a method for preventing corrosion of reactive metals provided in an embodiment of this application.

[0035] This application provides a method for preventing corrosion of reactive metals, comprising:

[0036] Step S101: Under a protective atmosphere, control the cemented carbide ball to slide along the surface of the active metal to be treated to perform surface dynamic extrusion treatment.

[0037] In the embodiments of this application, the contact surface between the cemented carbide ball and the active metal undergoes plastic deformation under high strain and high strain rate to obtain a nanocrystalline structure.

[0038] It should be noted that during the surface dynamic extrusion process, because the reduction is on the submicron scale, the surface material of the active metal (such as cerium-gallium alloy) is not removed, and the size remains unchanged. Due to the plastic deformation of the contact surface between the cemented carbide ball and the active metal under high strain and high strain rate, the grains gradually refine, producing a depth-dependent microstructure, and a nanocrystalline structure can be obtained on the surface.

[0039] In practical applications, the hard alloy ball can be made of WC-Co alloy. The reactive metal can be a cerium-gallium alloy.

[0040] Taking cerium-gallium alloy as an example, after dynamic extrusion treatment of the surface of cerium-gallium alloy, the segregation of gallium at the oxide film / substrate interface can effectively inhibit the diffusion of cerium and oxygen elements; the gallium element makes the oxide film formed on the surface of cerium alloy closer to the theoretical stoichiometry, and the oxygen ion vacancy concentration is low, which inhibits the diffusion of oxygen ions in the oxide film; the unit cell volume of the oxide is closer to the unit cell volume of the cerium matrix, thereby reducing the growth stress, effectively inhibiting the formation of oxide film cracks, and greatly improving the corrosion resistance of cerium-gallium alloy.

[0041] As an example, the protective atmosphere can be a liquid nitrogen protective atmosphere.

[0042] This application embodiment uses a surface dynamic extrusion process to treat a cerium-gallium alloy, forming a gradient nanostructure dominated by small-angle grain boundaries. The introduction of small-angle grain boundaries makes the surface denser, resulting in a denser oxide film compared to the untreated coarse grains. This inhibits oxygen diffusion and improves the cerium-gallium alloy's resistance to room temperature oxidation corrosion.

[0043] In a specific example, step S101 is preceded by:

[0044] Rotary forging of reactive metals into round bars;

[0045] The round bar is horizontally loaded onto the surface dynamic extrusion device, with both ends of the bar pressed together to facilitate surface dynamic extrusion processing.

[0046] In a specific example, step S101 may include:

[0047] A surface dynamic extrusion process with a rotation speed of 300 r / min, a feed rate of 0.01 mm / r, and a single pass pressing depth of 20 μm was used to control the sliding of the cemented carbide ball along the surface of the active metal.

[0048] In another example, step S101 further includes:

[0049] Lubricating oil is used for cooling during the sliding process.

[0050] In some possible implementations of the embodiments of this application, step S101 may be followed by:

[0051] The processed round bar was cut into 10mm×10mm×10mm samples using a wire cutting device.

[0052] The following detailed explanation, using a specific example, illustrates a method for preventing corrosion of reactive metals provided in this application.

[0053] This application provides a method for corrosion protection of active metals, taking cerium-gallium alloy with surface dynamic extrusion treatment technology as an example.

[0054] Step 1: The cerium-gallium alloy selected for the test material has a gallium content of 10.8 wt% and the remainder is cerium; Figure 2 An example is shown of the coarse-grained microstructure of an untreated cerium-gallium alloy. This cerium-gallium alloy consists of two phases: a shallow-contrast cerium-rich phase and a deep-contrast gallium-rich phase.

[0055] Step 2: After casting the cerium-gallium alloy using specialized equipment, it is then rotary forged under a protective atmosphere into a round bar with a diameter of φ22mm and a length of 150mm.

[0056] Step 3: Horizontally load the cerium-gallium alloy round bar onto the surface dynamic extrusion device, with both ends of the round bar pressed tightly together;

[0057] Step 4: A surface dynamic extrusion process with a rotation speed of 300 r / min, a feed rate of 0.01 mm / r, and a single pass of 20 μm is used to press a nanostructure onto the surface of the cerium gallium rod in one pass.

[0058] Figure 3 and Figure 4 The diagrams illustrate a surface dynamic extrusion treatment technology and the surface plastic deformation during the treatment process. Figure 5An example is shown illustrating the cross-sectional morphology of the cerium-gallium surface deformed microstructure after dynamic extrusion treatment. The area indicated by the white dashed line represents the plastic deformation layer, with an average thickness of approximately 35 μm. A gradient distribution of the cross-sectional microstructure can be observed, with the grain size gradually increasing continuously from the surface inwards, without obvious interfaces. The outermost layer exhibits uniform contrast, without obvious lamellar or mosaic distribution characteristics, indicating that plastic deformation leads to the dissolution of the two phases. The grains in this layer are equiaxed, with an average grain size of approximately 120 nm. As the depth of the deformed layer increases, the grains gradually become elongated. At a depth of 35 μm, the microstructure is comparable to that of the undeformed microstructure.

[0059] Step 5: Use a wire cutting device to cut the sample into 10mm×10mm×10mm pieces.

[0060] Oxidation was performed in a dry air atmosphere for 2000 hours, and the change in sample weight over time was analyzed to form an oxidation kinetic curve of time-weight gain, such as... Figure 6 As shown in the figure, by comparing the oxidation kinetic curves of the samples before and after treatment under the same conditions, it can be seen that the oxidation weight gain of the sample treated with surface rolling dynamic extrusion in a dry air atmosphere at room temperature is lower than that of the coarse-grained sample. This indicates that surface dynamic extrusion treatment can improve the oxidation resistance of cerium-gallium alloys.

[0061] Based on the active metal corrosion prevention method provided in the above embodiments, this application embodiment also provides an active metal, which is obtained by any one of the active metal corrosion prevention methods provided in the above embodiments.

[0062] The present application has been described in detail above with reference to the accompanying drawings and embodiments. However, the present application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present application. All content not described in detail in this application can be derived from existing technology.

Claims

1. A method for corrosion protection of reactive metals, characterized in that, The method includes: Under a protective atmosphere, the cemented carbide ball is controlled to slide along the surface of the active metal to be treated, and the surface dynamic extrusion treatment is carried out to form a gradient nanostructure dominated by small-angle grain boundaries. The contact surface between the cemented carbide ball and the active metal undergoes plastic deformation under high strain and high strain rate to obtain a nanocrystalline structure. The active metal is a cerium-gallium alloy.

2. The method for corrosion protection of reactive metals according to claim 1, characterized in that, The control of the cemented carbide ball sliding along the surface of the active metal to be treated further includes: The active metal is forged into a round bar by rotary forging. The round bar is horizontally loaded onto the surface dynamic extrusion device, with both ends of the round bar pressed together.

3. The method for corrosion protection of reactive metals according to claim 2, characterized in that, The control of the cemented carbide ball to slide along the surface of the active metal to be treated specifically includes: A surface dynamic extrusion process with a rotation speed of 300 r / min, a feed rate of 0.01 mm / r, and a single pass pressing depth of 20 μm is used to control the sliding of the cemented carbide ball along the surface of the active metal.

4. The method for corrosion protection of reactive metals according to claim 3, characterized in that, The control of the cemented carbide ball to slide along the surface of the active metal to be treated specifically includes: Lubricating oil is used for cooling during the sliding process.

5. The method for corrosion protection of reactive metals according to claim 3, characterized in that, The control of the cemented carbide ball to slide along the surface of the active metal further includes: The processed round bar was cut into 10mm×10mm×10mm samples using a wire cutting device.

6. The method for corrosion protection of reactive metals according to claim 1, characterized in that, The protective atmosphere is a liquid nitrogen protective atmosphere.

7. The method for corrosion protection of reactive metals according to any one of claims 1-6, characterized in that, The cemented carbide ball is made of WC-Co alloy.

8. A reactive metal, characterized in that, Obtained by using the method described in any one of claims 1-7.

Images