Fe-based laser cladding layer super-hydrophobic surface and construction method thereof

Abstract

The invention relates to the field of super-hydrophobic surfaces, and discloses a Fe-based laser cladding layer super-hydrophobic surface and a construction method thereof.The construction method comprises the steps that firstly, a base material with a submicron-nanocrystalline Fe-based cladding layer prepared on the surface is adopted, then the base material is subjected to high-temperature oxidation and heat preservation at the temperature of 580-620 DEG C for 50-70 minutes, and then the base material is cooled in air without chemical modification. The submicron-nanocrystalline Fe-VC cladding layer is selected, under the condition that no chemical surface modification exists, high-temperature oxidation process parameters are adjusted and controlled, the super-hydrophobic surface oxidation film layer is successfully obtained, and the maximum contact angle of the super-hydrophobic surface oxidation film layer reaches 151.2 degrees. A polarization curve fitting result shows that the corrosion current density of the super-hydrophobic film cladding layer is 0.795 [mu] A / cm < 2 > which is far lower than 4.282 [mu] A / cm < 2 > of an Fe-VC cladding layer. Therefore, compared with a cladding layer, the corrosion resistance of the super-hydrophobic film layer on the surface of the cladding layer prepared by the invention is obviously improved.

Description

Technical Field

[0001] The present invention relates to the field of superhydrophobic surfaces, and particularly to a superhydrophobic surface of an Fe-based laser cladding layer and a method for constructing the same. Background Art

[0002] As an advanced surface modification technology, laser cladding has broad application prospects. Preparing a cladding layer with low cost and excellent properties is the key to the wide application of this technology. Fe-based cladding powders have obvious price advantages, but their corrosion resistance needs to be improved. Inspired by nature, constructing a superhydrophobic film layer can greatly reduce the contact area between the corrosive medium and the material surface, effectively inhibit the infiltration, spreading, penetration and diffusion of the corrosive medium, delay the corrosion of metal materials, and show great application potential in the field of metal material corrosion and protection. At present, obtaining micro-nano structures and combining them with low surface energy material modification are the main means for constructing superhydrophobic surfaces, such as etching methods, self-assembly methods, spraying methods, chemical vapor deposition methods, electrospinning methods, etc. However, these methods all have their own limitations.

[0003] For example, Chinese Patent Publication No. CN110756414A discloses a high-performance superhydrophobic metal surface and a preparation method thereof. The preparation steps include: first, chemically etching a clean metal sample to obtain a metal surface with a micron structure, then soaking it in hot water and soaking it in a dispersion liquid of nanoparticles to graft nanoparticles, and finally soaking it in a solution of a low surface energy substance for surface modification to obtain the high-performance superhydrophobic metal surface. This technical solution obtains a superhydrophobic surface through chemical etching and chemical surface modification, and the preparation process is complex.

[0004] By virtue of the multi-scale micro-nano structure advantages of the sub-micro-nano crystalline Fe-based cladding layer, directly constructing a superhydrophobic surface in one step without chemical modification can significantly improve the corrosion resistance of the cladding layer. Therefore, it is of great significance to study the superhydrophobic surface of the Fe-based laser cladding layer and its construction method. Summary of the Invention

[0005] The technical problem to be solved by the present invention is: to provide a superhydrophobic surface of an Fe-based laser cladding layer and a method for constructing the same.

[0006] To solve the above technical problem, a method for constructing a superhydrophobic surface of an Fe-based laser cladding layer first uses a substrate with a sub-micro-nano crystalline Fe-based cladding layer on its surface, then oxidizes the substrate at a high temperature, keeps it at 580 - 620 °C for 50 - 70 minutes, and then cools it in air without chemical modification.

[0007] Preferably, the high-temperature oxidation is carried out at 600 °C for 1 hour.

[0008] Preferably, before the high-temperature oxidation, the surface of the cladding layer is polished.

[0009] Preferably, the method for preparing the cladding layer is as follows: a cladding layer is prepared on a substrate by laser cladding, and the alloy powder used in laser cladding includes 58.04 wt% to 62.03 wt% spherical iron powder, 32.18 wt% to 35.56 wt% FeV50 powder, and 5.79 wt% to 6.40 wt% graphite powder.

[0010] Preferably, the particle sizes of the three powders in the alloy powder are all 100 - 200 mesh.

[0011] Preferably, the alloy powder should be mixed evenly before laser cladding.

[0012] Preferably, the substrate is made of low-carbon steel, and pulsed laser is used for cladding. The duty cycle of the pulsed laser is 95%, the laser pulse frequency is 4400 - 4500 Hz, the laser power is 800 - 1000 W, the spot diameter is 2.0 mm, the laser scanning speed is 10 - 12 mm / s, the flow rate of protective argon gas is 10 - 12 L / min, the powder feeding gas is 5.6 - 6 L / min, and the powder feeding amount is 6 - 7 g / min.

[0013] Preferably, high-temperature oxidation is carried out in a muffle furnace.

[0014] The superhydrophobic surface of the Fe-based laser cladding layer of the present invention is prepared by using any one of the foregoing methods for constructing the superhydrophobic surface of the Fe-based laser cladding layer.

[0015] The beneficial effects of the present invention are as follows: The present invention selects a submicron-nanocrystalline Fe-VC cladding layer. Under the condition of no any chemical surface modification, by adjusting the high-temperature oxidation process parameters, a superhydrophobic surface oxide film layer is successfully obtained, and its maximum contact angle reaches 151.2°. From the fitting result of the polarization curve, it can be known that the corrosion current density of the superhydrophobic film layer cladding layer is 0.795 μA / cm 2 , which is much lower than that of the Fe-VC cladding layer, 4.282 μA / cm 2 . It can be seen from this that the corrosion resistance of the superhydrophobic film layer on the surface of the cladding layer prepared by the present invention is significantly improved compared with that of the cladding layer. Description of the Drawings

[0016] Figure 1 It is the optical micrograph of the cladding layer in Example 1;

[0017] Figure 2 It is the optical micrograph of the cladding layer in Example 2;

[0018] Figure 3 It is the optical micrograph of the cladding layer in Example 3;

[0019] Figure 4 It is the optical micrograph of the cladding layer in Example 4;

[0020] Figure 5 Optical micrograph of the cladding layer in Example 5

[0021] Figure 6 Secondary electron morphology image of the cladding layer in Example 1 obtained by scanning electron microscopy;

[0022] Figure 7 Secondary electron morphology image of the superhydrophobic film layer obtained by high-temperature oxidation of the cladding layer in Example 1 obtained by scanning electron microscopy;

[0023] Figure 8 Contact angle of the superhydrophobic film layer obtained by high-temperature oxidation of the cladding layer in Example 1;

[0024] Figure 9 Potentiodynamic polarization curves measured for the cladding layer and the superhydrophobic film layer in Example 1 in 3.5 wt.% NaCl solution;

[0025] Figure 10 Contact angle of the superhydrophobic film layer obtained by high-temperature oxidation of the cladding layer in Comparative Example 1;

[0026] Figure 11 Contact angle of the superhydrophobic film layer obtained by high-temperature oxidation of the cladding layer in Comparative Example 2;

[0027] Figure 12 Contact angle of the superhydrophobic film layer obtained by high-temperature oxidation of the cladding layer in Comparative Example 3;

[0028] Figure 13 Contact angle of the superhydrophobic film layer obtained by high-temperature oxidation of the cladding layer in Comparative Example 4;

[0029] Figure 14 Contact angle of the superhydrophobic film layer obtained by high-temperature oxidation of the cladding layer in Comparative Example 5. Detailed implementation manners

[0030] For the instruments, reagents, materials, etc. involved in the following examples, unless otherwise specified, they are all conventional instruments, reagents, materials, etc. existing in the prior art and can be obtained through regular commercial channels. For the experimental methods, detection methods, etc. involved in the following examples, unless otherwise specified, they are all conventional experimental methods, detection methods, etc. existing in the prior art.

[0031] In the following examples and comparative examples, a submicron-nanocrystalline Fe-based cladding layer was prepared on a low-carbon steel substrate by means of pulsed laser cladding with synchronous powder feeding. The alloy powder used for laser cladding should be mixed evenly before use. For example, all powders were mixed for 2 hours using a powder mixer. In the present invention, the mass content of V in FeV50 powder is 48%. The contact angle in the present invention is the static contact angle between the material surface and water. In the following examples and comparative examples, grinding and polishing means: rough grinding with water sandpaper and then grinding with 2**#-800**# metallographic sandpaper.

[0032] Example 1

[0033] Composition of alloy powder: 61.54 wt% spherical iron powder, 32.36 wt% FeV50 powder, 6.10 wt% graphite powder. The particle sizes of all three powders are 100 - 200 mesh. Laser cladding process parameters: Pulse laser duty cycle is 95%, laser pulse frequency is 4500 Hz, laser power is 1000 W, spot diameter is 2.0 mm, laser scanning speed is 12 mm / s, protective argon gas flow rate is 12 L / min, powder feeding gas is 6 L / min, powder feeding rate is 7 g / min, and the clad layer a is obtained. Grind and polish the surface of the clad layer of the clad sample, then put the clad sample into a muffle furnace for high-temperature oxidation, heat it from room temperature to 600 °C with the furnace and hold for 1 hour, and then cool it in air without chemical modification.

[0034] Example 2

[0035] Composition of alloy powder: 62.03 wt% spherical iron powder, 32.18 wt% FeV50 powder, 5.79 wt% graphite powder. The particle sizes of all three powders are 100 - 200 mesh. Laser cladding process parameters: Pulse laser duty cycle is 95%, laser pulse frequency is 4500 Hz, laser power is 1000 W, spot diameter is 2.0 mm, laser scanning speed is 12 mm / s, protective argon gas flow rate is 12 L / min, powder feeding gas is 6 L / min, powder feeding rate is 7 g / min, and the clad layer b is obtained. Grind and polish the surface of the clad layer of the clad sample, then put the clad sample into a muffle furnace for high-temperature oxidation, heat it from room temperature to 600 °C with the furnace and hold for 1 hour, and then cool it in air without chemical modification.

[0036] Example 3

[0037] Composition of alloy powder: 58.04 wt% spherical iron powder, 35.56 wt% FeV50 powder, 6.40 wt% graphite powder. The particle sizes of all three powders are 100 - 200 mesh. Laser cladding process parameters: Pulse laser duty cycle is 95%, laser pulse frequency is 4500 Hz, laser power is 1000 W, spot diameter is 2.0 mm, laser scanning speed is 12 mm / s, protective argon gas flow rate is 12 L / min, powder feeding gas is 6 L / min, powder feeding rate is 7 g / min, and the clad layer c is obtained. Grind and polish the surface of the clad layer of the clad sample, then put the clad sample into a muffle furnace for high-temperature oxidation, heat it from room temperature to 600 °C with the furnace and hold for 1 hour, and then cool it in air without chemical modification.

[0038] Example 4

[0039] Composition of alloy powder: 61.54 wt% spherical iron powder, 32.36 wt% FeV50 powder, 6.10 wt% graphite powder. The particle sizes of all three powders are 100 - 200 mesh. Laser cladding process parameters: Pulse laser duty cycle is 95%, laser pulse frequency is 4500 Hz, laser power is 800 W, spot diameter is 2.0 mm, laser scanning speed is 10 mm / s, protective argon gas flow rate is 12 L / min, powder feeding gas is 6 L / min, powder feeding rate is 6 g / min, and the cladding layer d is obtained. Grind and polish the surface of the cladding layer of the cladding specimen, then put the cladding specimen into a muffle furnace for high-temperature oxidation, heat it from room temperature to 600 °C along with the furnace and hold for 1 hour, and then cool it in air without chemical modification.

[0040] Example 5

[0041] Composition of alloy powder: 61.54 wt% spherical iron powder, 32.36 wt% FeV50 powder, 6.10 wt% graphite powder. The particle sizes of all three powders are 100 - 200 mesh. Laser cladding process parameters: Pulse laser duty cycle is 95%, laser pulse frequency is 4500 Hz, laser power is 900 W, spot diameter is 2.0 mm, laser scanning speed is 11 mm / s, protective argon gas flow rate is 12 L / min, powder feeding gas is 6 L / min, powder feeding rate is 6 g / min, and the cladding layer e is obtained. Grind and polish the surface of the cladding layer of the cladding specimen, then put the cladding specimen into a muffle furnace for high-temperature oxidation, heat it from room temperature to 600 °C along with the furnace and hold for 1 hour, and then cool it in air without chemical modification.

[0042] Control Example 1

[0043] Composition of alloy powder: 61.54 wt% spherical iron powder, 32.36 wt% FeV50 powder, 6.10 wt% graphite powder. The particle sizes of all three powders are 100 - 200 mesh. Laser cladding process parameters: Pulse laser duty cycle is 95%, laser pulse frequency is 4500 Hz, laser power is 1000 W, spot diameter is 2.0 mm, laser scanning speed is 12 mm / s, protective argon gas flow rate is 12 L / min, powder feeding gas is 6 L / min, powder feeding rate is 7 g / min. Grind and polish the surface of the cladding layer of the cladding specimen, no longer conduct high-temperature oxidation, and no chemical modification is required.

[0044] Control Example 2

[0045] Composition of alloy powder: 61.54 wt% spherical iron powder, 32.36 wt% FeV50 powder, 6.10 wt% graphite powder. The particle sizes of all three powders are 100 - 200 mesh. Laser cladding process parameters: Pulse laser duty cycle is 95%, laser pulse frequency is 4500 Hz, laser power is 1000 W, spot diameter is 2.0 mm, laser scanning speed is 12 mm / s, protective argon gas flow rate is 12 L / min, powder feeding gas is 6 L / min, and powder feeding rate is 7 g / min. Grind and polish the surface of the cladding layer of the cladding specimen, then put the cladding specimen into a muffle furnace for high-temperature oxidation. Heat it from room temperature to 600 °C along with the furnace and hold for 0.5 hour, and then cool it in air without chemical modification.

[0046] Control Example 3

[0047] Composition of alloy powder: 61.54 wt% spherical iron powder, 32.36 wt% FeV50 powder, 6.10 wt% graphite powder. The particle sizes of all three powders are 100 - 200 mesh. Laser cladding process parameters: Pulse laser duty cycle is 95%, laser pulse frequency is 4500 Hz, laser power is 1000 W, spot diameter is 2.0 mm, laser scanning speed is 12 mm / s, protective argon gas flow rate is 12 L / min, powder feeding gas is 6 L / min, and powder feeding rate is 7 g / min. Grind and polish the surface of the cladding layer of the cladding specimen, then put the cladding specimen into a muffle furnace for high-temperature oxidation. Heat it from room temperature to 600 °C along with the furnace and hold for 1.5 hours, and then cool it in air without chemical modification.

[0048] Control Example 4

[0049] Composition of alloy powder: 61.54 wt% spherical iron powder, 32.36 wt% FeV50 powder, 6.10 wt% graphite powder. The particle sizes of all three powders are 100 - 200 mesh. Laser cladding process parameters: Pulse laser duty cycle is 95%, laser pulse frequency is 4500 Hz, laser power is 1000 W, spot diameter is 2.0 mm, laser scanning speed is 12 mm / s, protective argon gas flow rate is 12 L / min, powder feeding gas is 6 L / min, and powder feeding rate is 6 g / min. Grind and polish the surface of the cladding layer of the cladding specimen, then put the cladding specimen into a muffle furnace for high-temperature oxidation. Heat it from room temperature to 600 °C along with the furnace and hold for 2 hours, and then cool it in air without chemical modification.

[0050] Control Example 5

[0051] Composition of alloy powder: 61.54 wt% spherical iron powder, 32.36 wt% FeV50 powder, 6.10 wt% graphite powder. The particle sizes of all three powders are 100 - 200 mesh. Laser cladding process parameters: Pulse laser duty cycle is 95%, laser pulse frequency is 4500 Hz, laser power is 1000 W, spot diameter is 2.0 mm, laser scanning speed is 12 mm / s, protective argon gas flow rate is 12 L / min, powder feeding gas is 6 L / min, and powder feeding amount is 6 g / min. Grind and polish the surface of the cladding layer of the cladding sample, then put the cladding sample into a muffle furnace for high-temperature oxidation. Heat it from room temperature to 600 °C with the furnace and hold for 2.5 hours, and then cool it in the air without chemical modification.

[0052] See Figure 1 , the optical micrograph of the cladding layer obtained in Example 1. It can be seen that the cladding layer is almost entirely composed of equiaxed grains, and the average grain size of the cladding layer is 0.87 μm.

[0053] See Figure 2 , the optical micrograph of the cladding layer obtained in Example 2. It can be seen that the grains of the cladding layer are fine, and the average grain size of the cladding layer is 0.95 μm.

[0054] See Figure 3 , the optical micrograph of the cladding layer obtained in Example 3. It can be seen that the grains of the cladding layer are fine, and the average grain size of the cladding layer is 0.96 μm.

[0055] See Figure 4 , the optical micrograph of the cladding layer obtained in Example 4. It can be seen that the grains of the cladding layer are fine, and the average grain size of the cladding layer is 0.94 μm.

[0056] See Figure 5 , the optical micrograph of the cladding layer obtained in Example 5. It can be seen that the grains of the cladding layer are fine, and the average grain size of the cladding layer is 0.89 μm.

[0057] From the above data, it can be seen that sub-micro-nano crystalline Fe-based cladding layers are obtained in Examples 1 - 5 after laser cladding.

[0058] See Figure 6 , the secondary electron micrograph of the cladding layer obtained in Example 1. Carbides are distributed at the grain boundaries, and the average particle size of the carbides is 75 nm.

[0059] See Figure 7, The secondary electron morphology image of the scanning electron microscope of the superhydrophobic film layer obtained by high-temperature oxidation of the cladding layer in Example 1 shows that the film layer is composed of micro-nano structures. Nano-sized blocks and linear objects are distributed on the micron-sized protruding cell bodies. Ultrafine-grained materials have smaller grain sizes and higher grain boundary densities, which makes the oxidation reaction more likely to occur at grain boundaries during high-temperature oxidation. A suitable holding time can make the formed oxide film more uniform and dense. The uniform and dense oxide film can effectively prevent the spalling and cracking of oxides, thus ensuring the stability of the micro-nano rough structure and facilitating the formation of superhydrophobic properties. The average grain size of the Fe-based cladding layer before high-temperature oxidation in Examples 1 to 5 is less than 1 μm, all reaching the ultrafine grain level. Therefore, a superhydrophobic film layer will also be formed after high-temperature oxidation.

[0060] See Figure 8 , The contact angle of the superhydrophobic film layer obtained by high-temperature oxidation of the cladding layer in Example 1 is 151.2°.

[0061] See Figure 9 , The potentiodynamic polarization curves of the cladding layer in Example 1 and the superhydrophobic film layer obtained by its high-temperature oxidation measured in a 3.5 wt.% NaCl solution. See Table 1 for the fitting results of the polarization curves measured for the cladding layer and the superhydrophobic film layer obtained by its high-temperature oxidation. It can be seen that the corrosion current density of the superhydrophobic film layer cladding layer is 0.79 μA / cm 2 , far lower than 4.28 μA / cm of the cladding layer 2 , indicating that the superhydrophobic film layer obtained by high-temperature oxidation effectively blocks the contact between the surface of the cladding layer and the corrosive medium.

[0062] Table 1 Fitting results of the polarization curves measured for the cladding layer and the superhydrophobic film layer obtained by its high-temperature oxidation

[0063]

[0064] Figure 10 The contact angle of the superhydrophobic film layer prepared in Comparative Example 1 is 87.7°.

[0065] Figure 11 The contact angle of the superhydrophobic film layer prepared in Comparative Example 2 is 138.7°.

[0066] Figure 12 The contact angle of the superhydrophobic film layer prepared in Comparative Example 3 is 134.1°.

[0067] Figure 13 The contact angle of the superhydrophobic film layer prepared in Comparative Example 4 is 86.6°.

[0068] Figure 14 The contact angle of the superhydrophobic film layer prepared in Comparative Example 5 is 74.5°.

[0069] Although embodiments of the present invention have been shown and described, those of ordinary skill in the art will appreciate that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for constructing a superhydrophobic surface on an Fe-based laser cladding layer, characterized in that: First, use a substrate with a sub-micro / nano-crystalline Fe-based cladding layer on its surface. Then, subject the substrate to high-temperature oxidation at 580 - 620 °C for 50 - 70 minutes, and then cool it in air without chemical modification.

2. The method for constructing a superhydrophobic surface of an Fe-based laser cladding layer according to claim 1, wherein: The high-temperature oxidation is carried out at 600 °C for 1 hour.

3. The method for constructing a superhydrophobic surface of an Fe-based laser cladding layer according to claim 1, characterized in that: Before high-temperature oxidation, first polish the surface of the cladding layer.

4. The method for constructing a superhydrophobic surface of an Fe-based laser cladding layer according to claim 1, characterized in that: The preparation method of the cladding layer is as follows: Use the laser cladding method to prepare the cladding layer on the substrate. The alloy powder used for laser cladding includes 58.04wt% - 62.03wt% spherical iron powder, 32.18wt% - 35.56wt% FeV50 powder, and 5.79wt% - 6.40wt% graphite powder.

5. The method for constructing a superhydrophobic surface of an Fe-based laser cladding layer according to claim 4, characterized in that: The particle sizes of the three powders in the alloy powder are all 100 - 200 mesh.

6. The method for constructing a superhydrophobic surface of an Fe-based laser cladding layer according to claim 4, characterized in that: The alloy powder should be mixed evenly before laser cladding.

7. The method for constructing a superhydrophobic surface of an Fe-based laser cladding layer according to claim 4, wherein: The substrate uses low-carbon steel, and pulsed laser is used for cladding. The duty cycle of the pulsed laser is 95%, the laser pulse frequency is 4400 - 4500 Hz, the laser power is 800 - 1000 W, the spot diameter is 2.0 mm, the laser scanning speed is 10 - 12 mm / s, the flow rate of protective argon gas is 10 - 12 L / min, the powder feeding gas is 5.6 - 6 L / min, and the powder feeding amount is 6 - 7 g / min.

8. The method for constructing a superhydrophobic surface of an Fe-based laser cladding layer according to claim 4, characterized in that: Carry out high-temperature oxidation in a muffle furnace.

9. A superhydrophobic surface of an Fe-based laser cladding layer, characterized in that: It is prepared by using the method for constructing a superhydrophobic surface of an Fe-based laser cladding layer according to any one of claims 1 - 8.

Images