Plasma uniform derusting system of iron-based porous metal structure

Abstract

The invention discloses a plasma uniform derusting system for an iron-based porous metal structure, which is characterized in that a metal structure to be derusted is arranged on a temperature control platform, and a discharge system performs glow discharge based on a plasma source to generate low-pressure plasma; and active particles in the low-pressure plasma enter the metal structure to be derusted, low-pressure discharge generates the active particles, and the active particles react with a rust layer and remove the rust layer. According to the scheme, active particles in the low-pressure plasma interact with the surface of the rust layer, such as physical action and chemical action, and surface layer heat energy accumulation is prevented based on surface temperature control, so that the surface layer temperature is continuously stabilized at room temperature; the temperature in the pore channels of the porous metal substrate is reduced to promote active particles in the plasma to enter gaps more easily, the active particles are promoted to react with rust layers in the pore channels, and no chemical reagents such as rust removers need to be added.

Description

Technical Field

[0001] The present invention belongs to the field of rust removal of iron-based metals, and particularly relates to a plasma uniform rust removal system for an iron-based porous metal structure. Background Art

[0002] Iron-based porous building metals are widely used in civil and military buildings. However, iron-based building metals are extremely vulnerable to the influence of complex environments such as high temperature and humid air during storage, resulting in surface rusting, which seriously affects their applications.

[0003] Although conventional chemical rust removal methods can remove the rust layer on the surface of iron-based metals, their isotropic rust removal characteristics inevitably cause corrosion inside the iron-based metals, affecting their surface smoothness and even metal specifications, and hindering their subsequent applications. For the surface of metal structural parts with complex structures, the aqueous solution used in chemical rust removal has a high surface tension, which makes it difficult for the rust remover to penetrate into the grooves and holes of the metal components, and uniform rust removal cannot be achieved. The use of strong acids will also affect the health of operators and corrode the surrounding equipment and environment.

[0004] Atmospheric pressure plasma jets can achieve uniform and harmless rust removal to a certain extent. CN107794548B and CN103484928A respectively disclose the rust removal methods of atmospheric pressure jet plasma and gas-liquid discharge plasma on the metal surface. Although the above methods have certain effects in rust removal on the material surface, they still face the problems of low efficiency and the introduction of strong acids and bases. At the same time, in the single rust removal process of jet plasma, only the material surface in millimeters can be processed, and the controllability is poor, which is extremely easy to damage the metal bracket and affect the surface smoothness. Summary of the Invention

[0005] In view of the above problems, the purpose of the present invention is to provide a plasma uniform rust removal system for an iron-based porous metal structure to achieve uniform rust removal on the surface of the iron-based porous metal structure, without introducing impurities such as rust removal liquid, capable of uniformly treating the surface rust layer, not causing damage to the surface of the iron-based metal, and particularly suitable for iron-based metals with high requirements for surface uniformity.

[0006] The specific technical solution for achieving the purpose of the present invention is as follows:

[0007] A plasma uniform rust removal system for an iron-based porous metal structure, comprising a discharge system and a temperature control platform;

[0008] The metal structure to be rust-removed is arranged on the temperature control platform, and the discharge system performs glow discharge based on a plasma source to generate low-pressure plasma;

[0009] Active particles in the low-pressure plasma enter the metal structure to be derusted. The low-pressure discharge generates active particles, which react with the rust layer and remove it.

[0010] Further, the temperature control platform determines the substrate surface temperature of the metal structure to be derusted during the derusting process through invasive and non-invasive detection methods;

[0011] The temperature control platform regulates the substrate surface temperature of the metal structure to be derusted by starting and stopping the coolant and controlling the flow rate.

[0012] Further, the temperature control platform uses infrared thermal imaging and thermocouples to determine the substrate surface temperature of the metal structure to be derusted during the derusting process;

[0013] The coolant of the temperature control platform uses any one or a mixture of water, methanol, and ethanol.

[0014] Further, the types of metal structures to be derusted include iron, steel bars, 304 stainless steel, 316 stainless steel, carbon steel, and silicon steel.

[0015] Further, the discharge methods of the discharge system include: AC discharge, RF discharge, microwave discharge, and helicon wave discharge;

[0016] The plasma source includes one or a combination of hydrogen, helium, argon, and water vapor.

[0017] Further, during the derusting process of the metal structure to be derusted, the gas flow rate of the plasma source is 10 - 300 sccm.

[0018] Further, before derusting, the metal structure to be derusted needs to maintain an ambient pressure of 0.1 - 0.01 Pa;

[0019] During the derusting process, the metal structure to be derusted needs to maintain an ambient pressure of 10 - 100 Pa.

[0020] Further, during the derusting process, the metal structure to be derusted needs to maintain a capacitive discharge electrode spacing of 10 - 80 cm.

[0021] Further, during the derusting process, the metal structure to be derusted needs to maintain a discharge power of 50 - 1000 W.

[0022] Further, the ambient temperature for the formation of the rust layer on the metal structure to be derusted is 25 - 500 °C, the ambient humidity is > 30%, and the formation duration is > 100 h.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] (1) The solution of the present invention is based on surface temperature control to prevent the accumulation of thermal energy on the surface, promote the entry of active particles into the interior of the porous structure. At the same time, the mutual physical and chemical interactions between the active particles in the plasma and the rust layer on the surface of the stent prevent the accumulation of thermal energy, and the surface temperature rises rapidly, resulting in a phase change of the rust layer, forming a denser rust layer on the substrate surface, making it difficult to fall off. The above process does not require the addition of any chemical reagents such as rust removers;

[0025] (2) The solution of the present invention controls the temperature of the metal surface to be derusted, keeps the surface temperature stable at room temperature continuously, and reducing the temperature inside the pores of the porous metal substrate will promote the easier entry of active particles in the plasma into the voids, and promote the reaction between the active particles and the rust layer in the pores;

[0026] (3) The solution of the present invention is based on the interaction between the active particles in the low-pressure plasma and the surface of the rust layer, including physical and chemical interactions. The physical interaction is that the active particles bombard the rust layer to separate the rust layer from the metal surface. The chemical interaction is that the hydrogen-containing active particles react with the oxide rust layer on the metal surface to convert the rust layer into soluble salts, and under the high-speed purging of the plasma flow, it is separated from the surface of the stent to achieve the purpose of rust removal.

[0027] The following further describes the present invention in conjunction with the accompanying drawings and specific embodiments. Description of the Drawings

[0028] Figure 1 It is a schematic diagram of the plasma uniform rust removal system architecture of the iron-based porous metal structure of the present invention.

[0029] Figure 2 It is a macroscopic photograph of the surface of 304 stainless steel in the embodiment of the present invention.

[0030] Figure 3 It is a macroscopic photograph of the rust layer on the surface of 304 stainless steel in the embodiment of the present invention.

[0031] Figure 4 It is a macroscopic photograph of the surface of 304 stainless steel after rust removal in the embodiment of the present invention.

[0032] Figure 5 It is a SEM schematic diagram of the surface of 304 stainless steel in the embodiment of the present invention.

[0033] Figure 6 It is a SEM schematic diagram of the rust layer on the surface of the iron-based porous metal structure in the embodiment of the present invention.

[0034] Figure 7 It is a SEM schematic diagram of the surface of the iron-based porous metal structure after rust removal in the embodiment of the present invention.

[0035] Figure 8XRD comparison diagrams before and after rust removal on the surface of the iron-based porous metal structure in the embodiments of the present invention. Detailed implementation manners

[0036] Combined with Figure 1 , a plasma uniform rust removal system for an iron-based porous metal structure, comprising a discharge system and a temperature control platform;

[0037] Place the metal structure to be rust-removed on the temperature control platform, and the discharge system performs glow discharge based on a plasma source to generate low-pressure plasma;

[0038] The active particles in the low-pressure plasma enter the metal structure to be rust-removed, and the low-pressure discharge generates active particles, which react with the rust layer and remove it.

[0039] The temperature control platform determines the substrate surface temperature of the metal structure to be rust-removed during the rust removal process through intervention and non-intervention detection methods;

[0040] The temperature control platform regulates the substrate surface temperature of the metal structure to be rust-removed by starting and stopping the coolant and controlling the flow rate.

[0041] The temperature control platform uses infrared thermal imaging and thermocouples to determine the substrate surface temperature of the metal structure to be rust-removed during the rust removal process;

[0042] The coolant of the temperature control platform uses any one or a mixture of water, methanol, and ethanol.

[0043] The types of metal structures to be rust-removed include iron, steel bars, 304 stainless steel, 316 stainless steel, carbon steel, and silicon steel.

[0044] The discharge methods of the discharge system include: alternating current discharge, radio frequency discharge, microwave discharge, and helicon wave discharge;

[0045] The plasma source includes a combination of one or more of hydrogen, helium, argon, and water vapor.

[0046] During the rust removal process of the metal structure to be rust-removed, the gas flow rate of the plasma source is 10 - 300 sccm, preferably 20 - 100 sccm.

[0047] Before rust removal, the metal structure to be rust-removed needs to maintain an ambient air pressure of 0.1 - 0.01 Pa, preferably 0.02 - 0.05 Pa;

[0048] During the rust removal process, the metal structure to be rust-removed needs to maintain an ambient air pressure of 10 - 100 Pa, preferably 30 - 60 Pa.

[0049] During the rust removal process, the metal structure to be rust-removed needs to maintain a capacitive discharge electrode spacing of 10 - 80 cm.

[0050] During the rust removal process, the metal structure to be rust-removed needs to maintain a discharge power of 50 - 1000 W, preferably 150 - 300 W.

[0051] The duration of the plasma uniform rust removal process is 1 - 100 s; preferably 5 - 30 s.

[0052] The environmental temperature for the formation of the rust layer on the metal structure to be rust-removed is 25 - 500 °C, the environmental humidity is > 30%, and the formation duration is > 100 h. Preferably, the temperature is 500 °C, the environmental humidity is 50%, and the rust formation duration is 20 h.

[0053] The area of the iron-based building metal in the plasma uniform rust removal process is 10 - 1000 cm2, and the thickness is 0.1 - 3 mm; preferably, the area is 10 - 400 cm2 and the thickness is 0.1 - 2 mm.

[0054] The number of pores in the porous structure during the plasma uniform rust removal process is 1 - 1000, the pore depth is 0.1 - 3 mm, and the pore depth-to-width ratio is 0.1 - 30. Preferably, the number of pores is 10 - 500, the pore depth is 0.1 - 3 mm, and the pore depth-to-width ratio is 0.1 - 30.

[0055] The surface temperature control system during the plasma uniform rust removal process can control the temperature of the surface at 20 - 500 °C to 20 °C with a deviation of < 1 °C.

[0056] The following further elaborates the present invention in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims of the patent application.

[0057] Example 1

[0058] In this embodiment, a radio frequency discharge system is used as the rust removal equipment, and 304 stainless steel is selected as the research object. First, a rust layer is formed on the surface of 304 stainless steel, and the rust formation environment parameters are: temperature 500 °C, humidity 50%, and rust formation duration 5 h.

[0059] The 304 stainless steel with a rust layer on its surface is used as the rust removal object. The dimensional characteristics of the 304 stainless steel are: area 150 cm2, thickness 2 mm, number of holes 20, and hole diameter 0.5 mm. The structural member is placed in the chamber to start the plasma uniform rust removal.

[0060] The formation process of the low-pressure plasma is as follows: The air pressure in the reaction chamber is reduced to 0.05 Pa through a molecular pump vacuum system; hydrogen is introduced through a gas pipeline on the chamber wall, and the gas flow rate is adjusted to maintain the chamber air pressure at 50 Pa; the discharge power and discharge distance are adjusted, and glow discharge is initiated. Secondly, during the discharge process, active particles continuously bombard the material surface, causing the surface temperature to continuously rise. Through the surface temperature control system, the surface reaction temperature is controlled at room temperature. At the same time, active hydrogen-containing particles undergo physical and chemical interactions with the rust layer on the surface of the iron-based porous metal. Since the surface temperature is at normal temperature and there is no heat energy accumulation in the pores, the active hydrogen-containing particles can smoothly enter the interior of the pores and undergo physical and chemical processes with the rust layer in the pores. After 20 s of treatment duration, the rust layer on the surface of the 304 stainless steel is completely removed, and the surface of the 304 stainless steel presents its original luster, and the surface is uniform and flat.

[0061] A macro camera is used to observe the color difference on the surface of the 304 stainless steel before and after treatment, including the surface color before oxidation (such as Figure 2 ), the surface color after oxidation (such as Figure 3 ), and the surface color after rust removal (such as Figure 4 ). As Figure 2 shows, the surface of the 304 stainless steel presents an obvious metallic color and is smooth. After the rust layer is generated, the metallic color on the surface disappears and a blue rust layer appears. After plasma rust removal, the surface restores the metallic color and is as smooth as before. A scanning electron microscope is used to detect whether the surface of the treated 304 stainless steel is smooth and whether there is a rust layer. If the concave-convex structure on the surface of the 304 stainless steel does not significantly decrease, it is regarded as unqualified. Figure 5 is the surface of the 304 stainless steel that is smooth. After rust is generated on the surface, a large amount of rust layer appears, and the rust layer presents an uneven morphology, as Figure 6 shows. After plasma treatment, the surface of the 304 stainless steel returns to the state before use, and the surface flatness is improved (such as Figure 7 ). It can be proved by X-ray diffraction (such as Figure 8 ) that the main component of the rust layer on the surface of the 304 stainless steel is iron-based oxide. After being treated by this method, the surface of the 304 stainless steel returns to the level before use.

[0062] Example 2

[0063] In this example, a microwave discharge system is used as the rust removal equipment, and carbon steel is selected as the research object. First, a rust layer is generated on the surface of the carbon steel, and the rust generation environment parameters are: temperature 25 °C, humidity 95%, and rust generation duration 48 h.

[0064] Carbon steel with a rust layer on its surface is used as the object for rust removal. The dimensional characteristics of the carbon steel are as follows: an area of 100 cm², a thickness of 0.5 mm, 40 surface pores, and a pore diameter of 2 mm. The structural component is placed in the chamber to start uniform plasma rust removal.

[0065] The formation process of the low-pressure plasma is as follows: Through the molecular pump vacuum system, the air pressure in the reaction chamber is reduced to 0.1 Pa; a hydrogen-argon mixed atmosphere is introduced simultaneously through multiple gas pipelines on the chamber wall, and the gas flow rate is adjusted to maintain the chamber air pressure at 40 Pa; the discharge power and discharge distance are adjusted, and glow discharge is initiated. Secondly, during the discharge process, active particles continuously bombard the material surface, causing the surface temperature to continuously rise. Through the surface temperature control system, the surface reaction temperature is controlled at room temperature. At the same time, the active hydrogen-containing particles undergo physical and chemical interactions with the rust layer on the surface of the carbon steel. After a treatment duration of 60 s, the rust layer on the surface of the carbon steel is completely removed, and the surface of the carbon steel presents its original luster and is uniform and flat.

[0066] Example 3

[0067] In this example, an alternating current discharge system is used as the rust removal equipment, and silicon steel is selected as the research object. First, a rust layer is generated on the surface of the silicon steel, and the rust generation environmental parameters are as follows: a temperature of 300 °C, a humidity of 50%, and a rust generation duration of 24 h.

[0068] Silicon steel with a rust layer on its surface is used as the object for rust removal. The dimensional characteristics of the silicon steel are as follows: an area of 300 cm², a thickness of 1 mm, 80 pore channels, and a pore diameter of 1 mm. The structural component is placed in the chamber to start uniform plasma rust removal. The formation process of the low-pressure plasma is as follows: Through the molecular pump vacuum system, the air pressure in the reaction chamber is reduced to 0.1 Pa; water vapor is introduced through a gas pipeline on the chamber wall, and the vapor flow rate is adjusted to maintain the chamber air pressure at 20 Pa; the discharge power and discharge distance are adjusted, and glow discharge is initiated. Secondly, during the discharge process, active particles continuously bombard the material surface, causing the surface temperature to continuously rise. Through the surface temperature control system, the surface reaction temperature is controlled at room temperature. At the same time, the active hydrogen-containing particles undergo physical and chemical interactions with the rust layer on the surface of the silicon steel. After a treatment duration of 120 s, the rust layer on the surface of the silicon steel is completely removed, and the surface of the silicon steel presents its original luster and is uniform and flat.

[0069] The above examples illustrate and describe the basic principles and main features of the present invention. Those skilled in the art of this industry should understand that the present invention is not limited by the above examples. What is described in the above examples and the specification only illustrates the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed.

Claims

1. A plasma uniform rust removal system for an iron-based porous metal structure, characterized in that: Including discharge system and temperature control platform; The metal structure to be derusted is placed on the temperature control platform, and the discharge system performs glow discharge based on a plasma source to generate low-pressure plasma; The active particles in the low-pressure plasma enter the metal structure to be derusted, and the low-pressure discharge generates active particles that react with the rust layer and remove it.

2. The plasma uniform rust removal system for iron-based porous metal structure according to claim 1, characterized in that: The temperature control platform determines the substrate surface temperature of the metal structure to be derusted during the derusting process by means of intervention and non-intrusive detection respectively; The temperature control platform regulates the substrate surface temperature of the metal structure to be derusted by starting and stopping the coolant and controlling the flow rate.

3. The plasma uniform rust removal system for iron-based porous metal structure according to claim 2, characterized in that: The temperature control platform uses infrared thermal imaging and thermocouples to determine the surface temperature of the substrate of the metal structure to be derusted during the derusting process; The cooling liquid of the temperature control platform is any one of water, methanol and ethanol or a mixture thereof.

4. The plasma uniform rust removal system for iron-based porous metal structure according to claim 1, characterized in that: The types of metal structures to be derusted include iron, steel bars, 304 stainless steel, 316 stainless steel, carbon steel, and silicon steel.

5. The plasma uniform rust removal system for iron-based porous metal structure according to claim 1, characterized in that: The discharge modes of the discharge system include: AC discharge, radio frequency discharge, microwave discharge, and spiral wave discharge; The plasma source includes one or a combination of hydrogen, helium, argon, and water vapor.

6. The plasma uniform rust removal system for iron-based porous metal structure according to claim 1, characterized in that: During the rust removal process of the metal structure to be rusted, the gas flow rate of the plasma source is 10-300 sccm.

7. The plasma uniform rust removal system for iron-based porous metal structure according to claim 1, characterized in that: The metal structure to be derusted must maintain an ambient pressure of 0.1-0.01 Pa before derusting; The metal structure to be derusted must maintain an ambient air pressure of 10-100Pa during the derusting process.

8. The plasma uniform rust removal system for iron-based porous metal structure according to claim 1, characterized in that: The metal structure to be derusted needs to maintain a capacitive discharge electrode spacing of 10-80 cm during the derusting process.

9. The plasma uniform rust removal system for iron-based porous metal structure according to claim 1, characterized in that: The metal structure to be derusted needs to maintain a discharge power of 50-1000W during the derusting process.

10. The plasma uniform rust removal system for iron-based porous metal structure according to claim 1, characterized in that: The rust layer of the metal structure to be derusted is generated in an environment with a temperature of 25-500° C., an environment with a humidity of >30%, and a generation time of >100 hours.

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