CN112144059A - Corrosion-resistant layer for galvanic corrosion protection of steel and aluminum alloy and preparation method thereof - Google Patents

Abstract

The invention discloses an anti-corrosion layer for galvanic corrosion protection of steel and aluminum alloy and a preparation method thereof, belonging to the technical field of surface engineering and corrosion protection. The corrosion-resistant layer comprises a composite corrosion-resistant layer cladded on the surface of an aluminum alloy substrate; the composite corrosion-resistant layer consists of a transition layer and a surface corrosion-resistant layer which are sequentially coated on the surface of the aluminum alloy substrate in a melting way; the transition layer comprises Ni: 10-25 wt.%; si: 1-2 wt.%; sn: 1-2 wt.%; cu: the balance; the surface corrosion resistant layer comprises Ni: 35-50 wt.%; cr: 5-10 wt.%; mo: 3-5 wt.%; w: 4-8 wt.%; si: 0.5-1 wt.%; cu: and (4) the balance. The transition layer and the surface corrosion-resistant layer are prepared on the surface of the aluminum alloy, and the surface corrosion-resistant layer is prepared on the surface of the steel, so that the potential difference of the contact surface of the aluminum alloy and the steel is reduced, and the galvanic corrosion problem caused by the coupling of the aluminum alloy and the steel in the marine environment is effectively solved.

Description

Corrosion-resistant layer for galvanic corrosion protection of steel and aluminum alloy and preparation method thereof

technical field

The invention belongs to the technical fields of surface engineering technology and corrosion protection, and in particular relates to a corrosion-resistant layer for galvanic corrosion protection of steel and aluminum alloy and a preparation method thereof.

Background technique

Because aluminum alloy has the characteristics of high specific strength, good seawater corrosion resistance, weldability, easy processing and forming, no low temperature brittleness, and no magnetism, it can effectively reduce the quality of ships, improve stability, and increase speed. Therefore, the current aluminum alloy has been widely used in ship components. Such as ship side, hull panel, porthole, handle and other parts. The chemical properties of aluminum are very active, and its equilibrium electrode potential (SCE) is -1.67V. The corrosion potential (SCE) of aluminum and its alloys in seawater is very negative, about -1250 to -850mV. In practical applications, aluminum alloy parts are inevitably coupled with steel equipment with higher potential. For example, the corrosion potential of marine steel is ≤-300mV. When aluminum alloys are coupled with steel, severe galvanic corrosion will occur.

5083 aluminum alloy with high corrosion resistance, excellent mechanical properties and weldability is widely used in ship hull structure, but the ship hull structure needs to be connected with various materials and equipment, so aluminum alloy ship plate is often in contact with steel. Due to the manufacturing process and working environment factors, the steel flange installed at the outlet of the exhaust pipe on the side is in contact with the aluminum alloy plate. Because the two metals are half immersed in water, and the temperature of the exhaust pipe is very high, this place Aluminum alloy plates are seriously corroded, and the edges of the openings often crack or perforate due to corrosion. In order to prevent the occurrence of galvanic corrosion, the protection treatment of galvanic corrosion shall be carried out when the steel flange is connected with the aluminum alloy plate. At the same time, due to the light weight, low density and high specific strength of aluminum alloy materials, it is often used as a maintenance port baffle. However, the potential difference between the aluminum plate and the steel body is more than 600mV. Therefore, an insulating transition layer is generally used when the aluminum plate and the steel body are coupled at the maintenance port to avoid direct contact between the aluminum alloy and the steel.

Galvanic corrosion protection on ships is mainly electrical insulation treatment, that is, through physical measures, electrical insulation and isolation of dissimilar metal coupling parts. For example, when the aluminum alloy material is connected with the steel flange, the insulating gasket shall be used to isolate the contact surface of the flange. However, due to assembly and other problems, problems such as failure of insulating devices and flange blocking devices often occur; at the same time, improper maintenance of aluminum alloy components often leads to failure of electrical insulation protection and leads to galvanic corrosion, which significantly reduces the service life of the equipment.

In view of the above problems, there is an urgent need to provide a corrosion-resistant layer and a preparation method for galvanic corrosion protection of steel and aluminum alloys.

SUMMARY OF THE INVENTION

In order to solve the above problems, the present invention proposes a corrosion-resistant layer for galvanic corrosion protection of steel and aluminum alloy, the corrosion-resistant layer includes a composite corrosion-resistant layer clad on the surface of the aluminum alloy substrate coupled with the steel substrate The composite corrosion-resistant layer is composed of a transition layer and a surface corrosion-resistant layer sequentially clad on the surface of the aluminum alloy substrate;

The transition layer includes the following components by weight: Ni: 10-25wt.%; Si: 1-2wt.%; Sn: 1-2wt.%; Cu: balance;

The surface corrosion-resistant layer includes the following components by weight: Ni: 35-50wt.%; Cr: 5-10wt.%; Mo: 3-5wt.%; W: 4-8wt.%; Si: 0.5-1wt. %; Cu: remainder.

The corrosion-resistant layer for galvanic corrosion protection of steel and aluminum alloy also includes a surface corrosion-resistant layer clad on the surface of the steel substrate.

The thickness of the transition layer is 150-300 μm, and the thickness of the surface corrosion-resistant layer is 400-800 μm.

Application of corrosion-resistant layers for galvanic corrosion protection of steel and aluminum alloys in marine environments to prevent galvanic corrosion of steel and aluminum alloys.

The method for preparing a corrosion-resistant layer for galvanic corrosion protection of steel and aluminum alloys comprises the following steps:

1) Melting of alloys

According to the composition ratio described in claim 1, the raw materials of the transition layer and the surface corrosion-resistant layer are respectively weighed, melted and processed in a smelting furnace, and heat-retained to obtain an alloy solution;

2) Atomization pulverizing

The alloy solution obtained in the above step 1) is placed in a crucible, respectively, and atomized and powdered to obtain alloy powder respectively;

3) Sieve to get finished powder

The alloy powder obtained in step 2) is respectively sieved to obtain a powder alloy material with a particle size of 140-400 meshes;

4) Surface treatment of the cladding substrate;

5) Put the powder alloy material obtained in step 3) into the powder storage container respectively, and fix the processed substrate obtained in step 4) on the cladding workbench, and sequentially laser clad the transition layer and the surface on the surface of the aluminum alloy substrate. Corrosion-resistant layer material; laser cladding surface corrosion-resistant layer material on the surface of the steel substrate;

6) Repeat step 5) to prepare a corrosion-resistant layer.

The holding temperature of the transition layer raw material in the melting furnace is 1300-1400 °C, and the holding time is 40-50 minutes; the holding temperature of the surface corrosion-resistant layer raw material in the melting furnace is 1400-1600 °C, and the holding time is 40-50 minute.

The required atomizing medium in step 2) is nitrogen, and the flow rate of the alloy solution is 0.4-1 kg/min.

In step 5), the cladding surface is the coupling surface between the aluminum alloy substrate and the steel substrate.

The method of laser cladding in step 5) is as follows: select a fiber laser with a power of 2-6kW as the heat source for cladding, the focal spot of the laser beam is 1-2mm, and a pneumatic synchronous powder feeder is used for powder feeding, and the powder feeding amount is 1-2 mm. 5kg/h, the powder feeder uses nitrogen to feed powder, and the gas supply is 10-20L/min. During the cladding process, Ar gas is used to protect the molten pool, and the gas supply is 10-20L/min; the relative relationship between the laser beam and the substrate The speed is 8-25cm/s; the cladding layer is prepared by the method of lap cladding. During single cladding, the lap rate of two adjacent cladding layers is 40-60%. The coating thickness is 150-800 μm.

During laser cladding, the cladding surface is kept horizontal, and the method is carried out by rotating the substrate and stepping the laser head along the radial direction.

Beneficial effects of the present invention:

1. The present invention utilizes high-speed laser cladding technology to effectively solve the problem by preparing a transition layer and a surface corrosion-resistant layer on the surface of the aluminum alloy, and preparing a surface corrosion-resistant layer on the steel surface to reduce the potential difference between the aluminum alloy and the steel interface. Galvanic corrosion caused by the coupling of aluminum alloy and steel in marine environment.

2. Using the surface corrosion-resistant layer material and the preparation method of the cladding layer of the present invention, the problems of peeling off, cracks and pores of the cladding layer on the surface of the aluminum alloy can be effectively solved.

Description of drawings

Figure 1 is a schematic cross-sectional view of the laser cladding layer on the surface of the aluminum alloy substrate.

Figure 2 is a schematic cross-sectional view of the laser cladding layer on the surface of the steel substrate.

3 is a schematic diagram of the connection between the aluminum alloy plate and the steel flange after laser cladding in Example 1.

Figure 4 is a schematic top view of the flange after laser cladding.

Fig. 5 is the actual picture of the laser cladding aluminum alloy flange in Example 2.

Fig. 6 is the actual picture of the aluminum alloy flange with laser cladding layer in Example 2

Fig. 7 is the actual picture of the aluminum alloy flange and the steel flange after laser cladding in Example 2.

8 is a galvanic current diagram of the aluminum alloy flange-steel flange coupling before and after laser cladding in Example 2.

Among them: 1 is the surface corrosion-resistant layer, 2 is the transition layer, 3 is the aluminum alloy substrate, 4 is the steel substrate, 5 is the aluminum alloy plate, 6 is the steel flange, 7 is the flange cladding area, and 8 is the laser head. 9 is an aluminum alloy flange.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments:

Since the aluminum alloy is easily oxidized in the air, an oxide film is formed on the surface. The oxide film has a high melting point and a large specific gravity. During the laser cladding process, it is easy to sink in the molten pool, resulting in inclusions or pores on the interface. Therefore, it is easy to cause low bonding strength between the cladding corrosion-resistant layer and the aluminum substrate interface and many interface defects. Aluminum alloys have strong negative electricity, and can combine with many elements in powder materials to form relatively brittle intermetallic compounds, which are prone to cracks. Aluminum alloy has high laser reflectivity and low solid solubility of Al, Cr, and Ni. If laser cladding is used to directly clad Ni-Cr-Mo corrosion-resistant alloy material on the surface of aluminum alloy, there will be a cladding corrosion-resistant layer and corrosion resistance. The problems of low bonding strength at the interface of the aluminum alloy matrix and the spalling failure of the cladding layer under the action of thermal stress.

The surface corrosion-resistant layer is made of Cu-Ni-Cr-Mo-W-Si alloy material. The Ni content in the alloy material is significantly higher than that in the alloy material used in the transition layer, which is beneficial to improve the corrosion resistance of the corrosion-resistant layer. ; The role of Cr, Mo, and W is to form a Cu-Ni-Cr-Mo-W solid solution, which has excellent corrosion resistance, not only in oxidizing media, but also in reducing media. ability.

The alloy powder composition of the transition layer contains four elements: Cu, Ni, Si, and Sn. During the laser cladding process, the transition layer and the matrix are mutually dissolved and diffused to form a metallurgical bond at the interface. Cu and Ni can dissolve infinitely, and Cu and Al can dissolve each other limitedly (the solid solubility of aluminum in copper is about 15.8%); within a wide range of Ni content, Ni and Al can form intermetallic compounds. Therefore, it is necessary to control the Ni content in the transition layer material composition within a certain range to achieve the purpose of reducing the generation of brittle phases (such as NiAl intermetallic compounds) and reducing cracks in the transition layer; Si element has a deoxidizing effect, and the cladding process It can inhibit the generation of oxide film and reduce the melting point of the aluminum alloy matrix; Sn element has the effect of solid solution strengthening and lowering the melting point, which is conducive to the formation of a good metallurgical bond between the transition layer and the aluminum alloy matrix and avoids the peeling of the cladding layer.

As shown in Fig. 1 and Fig. 2, in the scheme of preparing a corrosion-resistant layer on the coupling surface of steel and aluminum alloy according to the present invention: first, a transition layer 2 and a surface corrosion-resistant layer are sequentially prepared on the coupling surface of the aluminum alloy substrate 3 with the steel. 1; Among them, the transition layer 2 can connect the surface corrosion-resistant layer 1 and the aluminum alloy substrate 3 material, so that the physical and mechanical properties of the cladding layer can basically achieve gradient changes; then the surface corrosion-resistant layer is prepared on the steel substrate 4 and the aluminum coupling surface 1. Reduce the internal stress of the interface between the base material and the cladding layer, and prevent the cladding layer from cracking due to excessive thermal stress.

Example 1

Preparation of anti-corrosion layer on the coupling surface of aluminum plate and steel flange at the outlet of the exhaust pipe at the ship's side

1. Preparation method of alloy powder

1. Preparation of alloy powder for transition layer (referred to as powder A)

1) Melting of alloys

The raw materials are respectively weighed according to the following proportions, which include the following components by weight: Ni: 20wt.%; Si: 1wt.%; Sn: 1wt.%; Cu: balance.

First, add Cu into the vacuum intermediate frequency induction melting furnace for heating. After the Cu is completely melted, add the raw materials of other elements. When all the raw materials of the elements are completely melted, the molten alloy is kept at a temperature of 1350 ° C for 40 minutes.

2) Atomization pulverizing

The alloy solution obtained in the above step 1) is poured into a crucible of an atomization rapid condensation device, and the device is used for atomization and powder production to obtain Cu-Ni-Sn-Si alloy powder.

In the preparation method of the above alloy powder, the required atomization medium is nitrogen, and the flow rate of the alloy solution is 0.5kg/min.

3) Sieve to get finished powder

The alloy powder prepared in step 2) is sieved to obtain the powder material of the transition layer and the anti-corrosion layer for laser cladding, the particle size of which is in the range of 400-140 mesh.

2. Preparation of alloy powder for surface corrosion-resistant layer (referred to as powder B)

1) Melting of alloys

The raw materials are respectively weighed according to the following proportions, which include the following components by weight: the alloy powder material used in the surface corrosion-resistant layer, which includes the following components by weight: Ni: 40wt.%; Cr: 5wt.%; Mo: 3 wt.%; W: 5 wt.%; Si: 0.5 wt.%; Cu: balance.

First, add Ni and Cu into the vacuum intermediate frequency induction furnace for heating. After the Ni and Cu are completely melted, add the raw materials of other elements. When all the raw materials of the elements are completely melted, the molten alloy is kept at 1450°C for 40 minutes.

2) Atomization pulverizing

The alloy solution after the above step 1) is poured into a crucible of an atomization rapid condensation device, and the device is used to atomize powder to obtain Cu-Ni-Cr-Mo-W-Si alloy powder.

For the preparation methods of the above two alloy powders, the required atomization medium is nitrogen, and the flow rate of the alloy solution is 0.6 kg/min.

3) Sieve to get finished powder

The alloy powder prepared in step 2) is sieved to obtain the powder material of the transition layer and the anti-corrosion layer for laser cladding, the particle size of which is in the range of 400-140 mesh.

Second, the preparation method of the cladding layer

As shown in Figure 3, the workpiece to be clad is a marine 5083 aluminum alloy, the size is 150×150×10mm, the thickness is 10mm, the outer diameter of the steel flange is 190mm, the nominal diameter is 100mm, and the wall thickness is 12mm. Using high-speed laser cladding technology, a transition layer and a surface corrosion-resistant layer are prepared on the surface of the 5083 aluminum alloy plate 5, and a surface corrosion-resistant layer is prepared on the surface of the steel flange 6. The flange cladding area 7 is shown in Figure 4. The specific steps are as follows :

1. Preparation process of composite corrosion-resistant layer of aluminum alloy substrate

1) After derusting and degreasing the surface of the aluminum alloy plate, fix it on the cladding workbench.

2) Preparation of transition layer. The prepared transition layer alloy powder (powder A) was put into the powder storage container of the pneumatic powder feeder, and the transition layer was prepared by the method of static laser head, relative movement of aluminum alloy plate, and multi-pass lap joint. Argon gas was used as protective gas, and the gas supply volume was 15L/min, and nitrogen gas was used as powder supply gas, and the gas supply volume was 10L/min. The main parameters of cladding are: select a fiber laser with a power of 3kW for cladding, the diameter of the laser beam focus spot is 1.2mm, the output power of the fiber laser during cladding is 3kW, and the relative movement speed of the laser beam and the workpiece is 20cm/s; The overlap ratio of the cladding layer is 50%, and the average thickness of the formed transition layer is 160 μm.

3) Preparation of surface corrosion-resistant layer. After the transition layer cladding is completed, the prepared corrosion-resistant alloy powder (powder B) is put into the powder storage container of the pneumatic powder feeder, and is prepared by the method of static laser head, relative movement of aluminum alloy plate, and multiple lap joints. In the transition layer, argon is used as protective gas during the cladding process, and the gas supply is 15L/min, and nitrogen is used as powder gas, and the gas supply is 10L/min. The main parameters of cladding are: select a fiber laser with a power of 3kW for cladding, the diameter of the laser beam focus spot is 1.2mm, the output power of the fiber laser during cladding is 3kW, and the relative movement speed of the laser beam and the workpiece is 15cm/s; The overlap ratio of the cladding layer was 50%, and a surface corrosion-resistant layer with an average thickness of about 500 μm was prepared.

4) The aluminum alloy plate with the cladding layer is punched, and the hole diameter is d=14 mm.

1. Preparation process of surface corrosion-resistant layer of steel flange base

1) After derusting and degreasing the surface of the steel flange, fix it on the cladding workbench.

2) Put the prepared corrosion-resistant alloy powder (powder B) into the powder storage container of the pneumatic powder feeder, prepare the transition layer by using the method of static laser head, relative motion of steel flange, and multi-pass lap joint, and cladding In the process, argon gas was used as protective gas, and the gas supply volume was 15L/min, and nitrogen gas was used as powder supply gas, and the gas supply volume was 10L/min. The main parameters of cladding are: select a fiber laser with a power of 3kW for cladding, the diameter of the laser beam focus spot is 1.2mm, the output power of the fiber laser during cladding is 3kW, and the relative movement speed of the laser beam and the workpiece is 15cm/s; The overlap ratio of the cladding layer is 50%, and the thickness of the formed surface corrosion-resistant layer is about 500 μm.

The aluminum alloy plate with the composite corrosion-resistant layer is machined, and the thickness of the surface corrosion-resistant layer of the aluminum alloy substrate after processing is 450 μm, and the thickness of the surface corrosion-resistant layer of the steel flange is 400 μm.

Use M14 bolts to connect the aluminum alloy plate to the steel flange, as shown in Figure 3.

Example 2

As shown in Figure 7, the preparation of the corrosion-resistant layer of the aluminum alloy flange 9 and the steel flange 6

1. Preparation of alloy powder

1. Preparation of alloy powder for transition layer (referred to as powder C)

1) Melting of alloys

The raw materials are respectively weighed according to the following proportions, which include the following components by weight: Ni: 23wt.%; Si: 1.5wt.%; Sn: 1.5wt.%; Cu: balance.

First, add Cu into the vacuum intermediate frequency induction melting furnace for heating. After the Cu is completely melted, add the raw materials of other elements. When all the raw materials of the elements are completely melted, the molten alloy is kept at a temperature of 1400 ℃ for 40 minutes.

2) Atomization pulverizing

The two alloy solutions after the above step 1) are respectively poured into a crucible of an atomization rapid condensation device, and the device is used to atomize powder to obtain Cu-Ni-Sn-Si alloy powder.

In the preparation method of the above alloy powder, the required atomization medium is nitrogen, and the flow rate of the alloy solution is 0.6 kg/min.

3) Sieve to get finished powder

The alloy powder prepared in step 2) is sieved to obtain the powder material of the transition layer and the anti-corrosion layer for laser cladding, the particle size of which is in the range of 400-140 mesh.

2. Preparation of alloy powder for surface corrosion-resistant layer (referred to as powder D)

1) Melting of alloys

Weigh the raw materials respectively according to the following proportions, which include the following components by weight: the alloy powder material used in the surface corrosion-resistant layer, which includes the following components by weight: Ni: 45wt.%; Cr: 8wt.%; Mo: 5 wt.%; W: 7 wt.%; Si: 0.5 wt.%; Cu: balance.

First, add Ni and Cu into the vacuum intermediate frequency induction furnace for heating. After the Ni and Cu are completely melted, add the raw materials of other elements. When all the raw materials of the elements are completely melted, the molten alloy is kept at 1500 ℃ for 50 minutes.

2) Atomization pulverizing

The two alloy solutions after the above step (1) are respectively poured into a crucible of an atomization rapid condensation device, and the device is used for atomization and powder production to obtain Cu-Ni-Cr-Mo-W-Si alloy powder.

For the preparation methods of the above two alloy powders, the required atomization medium is nitrogen, and the flow rate of the alloy solution is 0.7kg/min.

3) Sieve to get finished powder

The alloy powder prepared in step 2) is sieved to obtain the powder material of the transition layer and the anti-corrosion layer for laser cladding, the particle size of which is in the range of 400-140 mesh.

2. Preparation process of surface corrosion-resistant layer

The workpiece to be clad is aluminum alloy flange and steel flange. Using high-speed laser cladding technology, a transition layer and a surface corrosion-resistant layer are prepared on the surface of the aluminum alloy flange base, and a surface corrosion-resistant layer is prepared on the surface of the steel flange base. The specific steps are as follows:

1. Preparation process of composite corrosion-resistant layer of aluminum alloy substrate

1) After derusting and degreasing the surface of the aluminum alloy flange, fix it on the cladding workbench.

2) Preparation of transition layer. The prepared transition layer alloy powder (powder C) is put into the powder storage container of the pneumatic powder feeder, as shown in Figure 5, and the laser head 8 is static, the aluminum alloy plate is in relative motion, and the method is prepared by multiple lap joints. In the transition layer, argon is used as protective gas during the cladding process, and the gas supply is 15L/min, and nitrogen is used as powder gas, and the gas supply is 10L/min. The main parameters of cladding are: select a fiber laser with a power of 3kW for cladding, the diameter of the laser beam focus spot is 1.2mm, the output power of the fiber laser during cladding is 3kW, and the relative movement speed of the laser beam and the workpiece is 18cm/s; The overlap ratio of the cladding layer is 50%, and the average thickness of the formed transition layer is 200 μm.

3) Preparation of surface corrosion-resistant layer. After the transition layer cladding is completed, the prepared corrosion-resistant alloy powder (powder D) is put into the powder storage container of the pneumatic powder feeder, and is prepared by the method of static laser head, relative movement of aluminum alloy plate, and multiple lap joints. In the transition layer, argon is used as protective gas during the cladding process, and the gas supply is 15L/min, and nitrogen is used as powder gas, and the gas supply is 10L/min. The main parameters of cladding are: select a fiber laser with a power of 3kW for cladding, the diameter of the laser beam focus spot is 1.2mm, the output power of the fiber laser during cladding is 3kW, and the relative movement speed of the laser beam and the workpiece is 12cm/s; The overlap ratio of the cladding layer is 50%, and a surface corrosion-resistant layer with an average thickness of about 650 μm is prepared. After the cladding of the aluminum alloy flange is completed, it is shown in Figure 6.

2. Preparation process of surface corrosion-resistant layer of steel flange base

1) After derusting and degreasing the surface of the steel flange, fix it on the cladding workbench.

2) Put the prepared corrosion-resistant alloy powder (powder D) into the powder storage container of the pneumatic powder feeder, prepare the transition layer by using the method of static laser head, relative movement of steel flange, and multi-pass lap joint, and cladding In the process, argon gas was used as protective gas, and the gas supply volume was 15L/min, and nitrogen gas was used as powder supply gas, and the gas supply volume was 10L/min. The main parameters of cladding are: select a fiber laser with a power of 3kW for cladding, the diameter of the laser beam focus spot is 1.2mm, the output power of the fiber laser during cladding is 3kW, and the relative movement speed of the laser beam and the workpiece is 13cm/s; The overlap ratio of the cladding layer is 50%, and the thickness of the formed surface corrosion-resistant layer is about 600 μm.

The aluminum alloy flange with surface corrosion-resistant layer is machined. After processing, the remaining thickness of the corrosion-resistant layer on the surface of the aluminum alloy flange is 450 μm, and the thickness of the corrosion-resistant layer on the surface of the steel flange is 400 μm.

Use M16 bolts to connect the aluminum alloy flange to the steel flange.

As shown in Figure 8, the galvanic corrosion susceptibility test was carried out on the steel substrate and aluminum alloy substrate before and after laser cladding the corrosion-resistant layer. After continuous testing for 10 h, the average galvanic current density of the steel-aluminum galvanic pair was 1.5×10 ^{− 5} A·cm ⁻² , the galvanic corrosion sensitivity is E grade (E grade: 10.0 μA/cm ² ≤ig). The average galvanic current density of the galvanic couple of the steel substrate and the aluminum alloy substrate after laser cladding the surface corrosion-resistant layer and the composite corrosion-resistant layer respectively is 7.8×10 ^-8 A·cm ^-2 , and the galvanic corrosion sensitivity reaches A level (ig≤0.3μA/cm ² ). Through the implementation of the present invention, the galvanic corrosion sensitivity of the steel-aluminum alloy coupling part and the entire steel-aluminum alloy coupling structure is significantly reduced, and the galvanic corrosion protection of the steel and the aluminum alloy is realized.

Industrial Applicability

The process and the alloy material of the present invention reduce the potential difference of the contact surface between the aluminum alloy and the steel by preparing the transition layer and the surface anti-corrosion layer on the surface of the aluminum alloy and the surface anti-corrosion layer on the surface of the steel, and effectively solve the problem of the difference between the contact surface of the aluminum alloy and the steel in the marine environment. The galvanic corrosion problem caused by the coupling of aluminum alloys prolongs the service life of the two and steel-aluminum alloy couplings, and has good industrial practicability.

Claims (10)

1. a corrosion-resistant layer for galvanic corrosion protection of steel and aluminum alloy, characterized in that the corrosion-resistant layer comprises a composite corrosion-resistant layer cladding on the surface of an aluminum alloy substrate; the composite corrosion-resistant layer is sequentially The transition layer and the surface corrosion-resistant layer clad on the surface of the aluminum alloy substrate are composed; The transition layer includes the following components by weight: Ni: 10-25wt.%; Si: 1-2wt.%; Sn: 1-2wt.%; Cu: balance; The surface corrosion-resistant layer includes the following components by weight: Ni: 35-50wt.%; Cr: 5-10wt.%; Mo: 3-5wt.%; W: 4-8wt.%; Si: 0.5-1wt. %; Cu: remainder. 2 . The corrosion-resistant layer according to claim 1 , further comprising a surface corrosion-resistant layer cladding on the surface of the steel substrate. 3 . 3 . The corrosion-resistant layer according to claim 1 , wherein the thickness of the transition layer is 150-300 μm, and the thickness of the surface corrosion-resistant layer is 400-800 μm. 4 . 4. Application of the corrosion-resistant layer for galvanic corrosion protection of steel and aluminum alloy according to any one of claims 1-3 in marine environment to prevent galvanic corrosion of steel and aluminum alloy. 5. the preparation method of the corrosion-resistant layer for steel and aluminum alloy galvanic corrosion protection described in any one of claim 1-3, is characterized in that, comprises the following steps: 1) Melting of alloys According to the composition ratio described in claim 1, the raw materials of the transition layer and the surface corrosion-resistant layer are respectively weighed, melted and processed in a smelting furnace, and heat-retained to obtain an alloy solution; 2) Atomization pulverizing The alloy solution obtained in the above step 1) is placed in a crucible, respectively, and atomized and powdered to obtain alloy powder respectively; 3) Sieve to get finished powder The alloy powder obtained in step 2) is respectively sieved to obtain a powder alloy material with a particle size of 140-400 meshes; 4) Surface treatment of the cladding substrate; 5) Put the powder alloy material obtained in step 3) into the powder storage container respectively, and fix the processed substrate obtained in step 4) on the cladding workbench, and sequentially laser clad the transition layer and the surface on the surface of the aluminum alloy substrate. Corrosion-resistant layer material; laser cladding surface corrosion-resistant layer material on the surface of the steel substrate; 6) Repeat step 5) to prepare a corrosion-resistant layer. 6. The preparation method according to claim 5, wherein the holding temperature of the transition layer raw material in the smelting furnace is 1300°C-1400°C, and the holding time is 40 minutes-50 minutes; The holding temperature is 1400-1600 ℃, and the holding time is 40-50 minutes. 7. The preparation method according to claim 5, wherein the required atomization medium in step 2) is nitrogen, and the alloy solution flow rate is 0.4-1kg/min. 8 . The preparation method according to claim 5 , wherein the cladding surface in step 5) is the coupling surface between the aluminum alloy base and the steel base. 9 . 9. preparation method according to claim 5, is characterized in that, the method for laser cladding in step 5) is: select the fiber laser of power 2-6kW as the heat source for cladding, the laser beam focus spot is 1-2mm, Pneumatic synchronous powder feeder is used for powder feeding, and the powder feeding rate is 1-5kg/h. The powder feeder uses nitrogen gas for powder feeding, and the gas feeding rate is 10-20L/min. During the cladding process, Ar gas is used to protect the molten pool. , the air supply is 10-20L/min; the relative speed of the laser beam and the substrate is 8-25cm/s; the cladding layer is prepared by the method of lap cladding. The overlap ratio is 40-60%, and the thickness of the cladding layer formed by single-layer cladding is 150-800 μm. 10 . The preparation method according to claim 9 , characterized in that, during laser cladding, the cladding surface is kept horizontal, and the method is performed by rotating the substrate and stepping the laser head along the radial direction. 11 .

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