CN106191829A - A preparation method of micro-nano multi-scale structure on the surface of medium carbon steel - Google Patents

Abstract

The invention discloses a preparation method of a micro-nano multi-scale structure on the surface of medium carbon steel, which adopts a particle shot blasting method to construct a multi-scale structure on the surface of medium carbon steel in situ to obtain the surface of medium carbon steel with the micro-nano multi-scale structure, and then carries out chemical modification by a low surface energy reagent to ensure that the medium carbon steel has super-hydrophobic characteristics. The low surface energy reagent is fluorosilane/absolute ethyl alcohol solution or fluorosilane/normal hexane solution. The method has no special requirements on equipment, and has the characteristics of flexible and simple process, low preparation cost, in-situ construction of a multi-scale structure and reinforcement of the surface of the medium carbon steel, and particularly controllable appearance of the surface multi-scale structure.

Description

A preparation method of micro-nano multi-scale structure on the surface of medium carbon steel

technical field

The invention belongs to the field of superhydrophobic surface preparation, and more specifically relates to a method for preparing a micro-nano multi-scale structure on the surface of a metal material and its application.

Background technique

Medium carbon steel is widely used in construction, machinery, transportation and other fields because of its low price, easy material acquisition, easy processing, and good mechanical properties. In the face of so many applications, in addition to mechanical properties, medium carbon steel also needs to have some surface properties, such as self-cleaning, anti-fouling, underwater drag reduction, etc. To achieve these surface properties, it is necessary to make the medium carbon steel surface superhydrophobic. The superhydrophobicity of a solid surface is mainly related to the physical and chemical states of the surface, which refer to the rough factor and surface energy, respectively. Therefore, the following two types of methods are usually used to prepare solid superhydrophobic surfaces: one is to roughen the surface with low surface energy to make the low-energy surface rough. This method is only applicable to organic polymer solid materials with low surface energy. It can be implemented above, but it is obviously not suitable for medium carbon steel materials. The other category is for solid substances that do not have low-energy surfaces, including metals and nonmetals. Chemical modification of the rough surface to make the rough surface have low surface energy, often suitable for medium carbon steel materials. In order to make the rough surface have low surface energy, it is often suitable for medium carbon steel materials. In order to construct a rough surface on a metal substrate, the existing methods include laser etching, vapor deposition, etc., which require large-scale equipment, and also include simple and easy electrodeposition, chemical deposition, anodic oxidation, chemical etching, etc. Among them, anodic oxidation is suitable for passivated metals, also known as valve metals, such as Al, Mg, Ti, etc., but not suitable for medium carbon steel; laser etching and vapor deposition are suitable for medium carbon steel, But the cost is high; electrodeposition and chemical deposition are simple, but there is a problem of bonding between the coating and the substrate; chemical etching is simple and easy, but the controllability of the rough structure is not high. Patents CN105386032A and CN105386101A use the sandblasting method to roughen the metal surface to prepare a super-hydrophobic surface. The medium is quartz sand, steel sand, etc. The sand is in an irregular shape, and its main function is to clean the surface and roughen the substrate. The multi-scale concave-convex topography of the surface has the disadvantage of being uncontrollable.

Contents of the invention

The object of the present invention is to overcome the shortcoming of the method for preparing the superhydrophobic surface of medium carbon steel in the prior art, and provide a method for preparing micro-nano multi-scale structures on the surface of medium carbon steel. The method does not require large-scale equipment, and the process is flexible and simple. The preparation cost is low, and the multi-scale rough structure is constructed in situ with controllable morphology. At the same time, the surface of the medium carbon steel is strengthened and has a super-hydrophobic structure.

The above-mentioned purpose of the present invention is achieved through the following technical solutions:

A method for preparing a micro-nano multi-scale structure on the surface of medium carbon steel, comprising the following specific steps:

S1. First polish the surface of the medium carbon steel with 120-1000 mesh sandpaper, then polish the surface of the medium-carbon steel with a polishing agent for 5-10 minutes, and pretreat the surface of the medium-carbon steel to obtain a polished surface;

S2. Using the particle shot peening process, install the medium carbon steel treated in step S1 on the clamping table inside the shot blasting machine, set the distance between the nozzle of the spray gun and the polished surface to be shot peened at 5-15 cm, and the shot peening pressure at 0.1-0.4 MPa, turn on the power supply of the shot blasting machine, and turn on the air compressor, process the medium carbon steel with particle shot peening, build a rough surface structure in situ, and dry it with cold air after cleaning;

S3. Soak the medium-carbon steel treated in step S2 in a low surface energy reagent for chemical modification, and then wash and dry to obtain a medium-carbon steel surface with superhydrophobic properties.

Preferably, the polishing agent described in step S1 is diamond suspension or diamond polishing paste.

Preferably, the particulate projectiles described in step S2 are atomized stainless steel spherical projectiles, and the average diameters of the projectiles are 50 μm and 150 μm.

Preferably, the particle shot peening process described in step S2 is divided into either A or B,

Among them, the A process adopts two shots of particle shot peening. First, the surface of the medium carbon steel is sprayed with projectiles with an average diameter of 150 μm for 1 to 4 minutes, and then the surface of the medium carbon steel is sprayed with projectiles with an average diameter of 50 μm. 1 to 7 minutes to obtain multi-scale surface structures;

Process B adopts single-pass mixed shot peening, mixes shot peening with an average diameter of 150 μm and 50 μm at a ratio of 1:1 to 2 in total mass, and sprays the surface of medium carbon steel with the mixed shot for 1 to 7 minutes. Get multi-scale surface structures.

Preferably, the low surface energy agent in step S3 is a fluorosilane/absolute ethanol solution or a fluorosilane/n-hexane solution, and the soaking time is 10-60 minutes.

Preferably, the solution used for cleaning in steps S2 and S3 is absolute ethanol.

The invention realizes the construction of multi-scale rough structure. For a single projectile, a spherical projectile with a diameter of micron scale, under the push of compressed gas, hits the surface of medium carbon steel, and the surface of medium carbon steel undergoes plastic deformation to form a dimensional A dimple below the projectile diameter. Projectiles of different sizes produce pits of different sizes. After being hit by a large number of projectiles, these pits of different sizes will superimpose and overlap, and the surface of the medium carbon steel will form a rough texture with unevenness, that is, the target rough structure. In addition, the blasting medium also plays a key role. Usually, the quartz sand or steel sand used for sandblasting is irregular in shape, large in size, brittle, and the micro-nano multi-scale morphology of the surface is uncontrollable; glass beads and ceramic beads also have particles Big fragile problem. The projectiles used in the present invention are atomized stainless steel shots, which are fine spherical particles with a certain toughness and are not brittle in comparison. The construction of multi-scale rough structures can be completed through projectile mixing or multi-pass shot peening. Moreover, through fluorosilane modification, the surface free energy of medium carbon steel is reduced, and the synergistic effect is used to realize a superhydrophobic structure on the rough surface.

The invention builds a multi-level scale rough structure in situ, avoiding the problem of binding force that exists when depositing a layer of foreign coating with a rough appearance on the metal surface when the generally adopted deposition method is used to prepare the rough structure. In addition to the adjustable shot diameter and its ratio, the process parameters involved in the shot peening process include: shot peening time, shot peening pressure, and shot peening distance (the distance between the nozzle and the polished surface to be shot). Changing the shot peening time is equivalent to changing the number of impacts, which ultimately changes the number of craters and the coverage of the craters on the surface of the medium carbon steel; the projectiles gain speed under the push of compressed air. different. Therefore, changing the peening pressure is equivalent to changing the impact force, which ultimately changes the depth of the crater; changing the peening distance is equivalent to changing the size of the radiation surface of the projectile flow, and finally changes the size of the sprayed area on the medium carbon steel surface. By adjusting the above parameters, the control of rough structure morphology can be realized.

Compared with the prior art, the present invention has the following beneficial effects:

1. The present invention adopts two optional methods of two-pass particle shot peening process and single-pass mixed shot peening process to realize the in-situ construction of multi-level scale rough structures on the surface of medium carbon steel, which solves the problem of deposition method preparation The problem of the adhesion between the coating and the substrate exists in the rough surface structure.

2. The present invention builds a rough structure on the surface of medium carbon steel by adjusting the diameter of the projectile and its ratio, and at the same time adjusts the process parameters of the shot peening process, such as shot peening time, shot peening pressure, and the distance between the nozzle and the surface of the medium carbon steel. , to realize the regulation of rough structure morphology.

3. In addition to realizing the construction of the rough structure on the surface of the medium carbon steel, the present invention also strengthens the surface of the medium carbon steel. Moreover, no large-scale equipment is required, and all operations can be realized by a small pneumatic shot blasting machine, so the preparation cost is low.

Description of drawings

Figure 1 is a schematic diagram of the process of constructing a rough structure on the surface of medium carbon steel by the two-pass method. a is a schematic diagram of a single projectile impacting the surface of medium carbon steel; b is a schematic diagram of the rough structure constructed on the surface of medium carbon steel. Among them: 1 is a single projectile, 2 is the surface of medium carbon steel, 3 is a single crater, 4 is the rough surface structure caused by the impact of multiple projectiles in the first shot during two shots, 5 is the multi-shot surface caused by two shots Scale coarse structure.

Fig. 2 is a 3D image of the atomic force microscope of the surface morphology of medium carbon steel after particle shot peening in Example 1.

FIG. 3 is an image of water droplets on the surface of medium carbon steel with micro-nano multi-scale structure prepared in Example 1. FIG.

detailed description

The content of the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but it should not be construed as a limitation of the present invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the technical field.

Example 1 Preparation of multi-scale structures on the surface of medium carbon steel by two-pass shot peening

1. Pretreatment: first use 120 mesh, 280 mesh, 320 mesh, 400 mesh, 600 mesh, 800 mesh, 1000 mesh sandpaper to polish 45# medium carbon steel (where C is 0.42~0.50%, Si: 0.17~0.37% , Mn: 0.50～0.80%, P: ≤0.035%, S: ≤0.035%, Cr: ≤0.25%) surface, and then use 1μm diamond suspension on the polishing machine to polish the grinding surface to obtain a polished surface, which is a rough surface Prepare for the construction of the structure.

2. Construction of multi-scale rough structure: Install the polished 45# medium carbon steel on the clamping table inside the shot blasting machine, connect the power supply of the shot blasting machine, and connect the air compressor to perform particle shot peening. The parameters of the first shot peening process are: the average diameter of the shot is 150 μm, the distance between the nozzle and the steel surface is 10 cm, the shot peening pressure is 0.3 MPa, and the shot peening time is 1 min. The parameters of the second shot peening process are: the average diameter of the shot is 50 μm, the distance between the nozzle and the steel surface is 10 cm, the shot peening pressure is 0.1 MPa, and the shot peening time is 2 minutes. After the two shot peening processes are completed, clean the shot peening surface with absolute ethanol and dry it for later use.

3. Chemical modification: Soak the 45# medium carbon steel after shot peening in the n-hexane solution of perfluorododecyltrichlorosilane with a concentration of 0.2% (volume percentage) for 30 minutes, clean it with absolute ethanol and blow it. Dry.

Figure 1 is a schematic diagram of the process of constructing a rough structure on the surface of medium carbon steel by the two-pass method. a is a schematic diagram of a single projectile impacting the surface of medium carbon steel; b is a schematic diagram of the rough structure constructed on the surface of medium carbon steel. Among them: 1 is a single projectile, 2 is the surface of medium carbon steel, 3 is a single crater, 4 is the rough surface structure caused by the impact of multiple projectiles in the first shot during two shots, 5 is the multi-shot surface caused by two shots Scale coarse structure. A single spherical projectile with a micron-scale diameter hits the surface of the medium carbon steel under the push of compressed gas, and the surface of the medium carbon steel undergoes plastic deformation to form a pit whose size is smaller than the diameter of the projectile, as shown in Figure 1a. When a large number of projectiles are ejected, the projectile flow formed hits the surface of the medium carbon steel, forming continuous pits. The projectiles sprayed by the first pass of shot peening have a larger diameter, forming larger-scale pits, and the projectiles sprayed by the second pass of shot peening have smaller diameters, forming smaller-scale pits. The small-scale pits are superimposed on the large-scale pits to form a multi-scale rough structure, as shown in Figure 1b. However, in the process of constructing a rough structure on the surface of medium carbon steel by the single-pass method, due to the mixture of projectiles of different sizes, the structure shown in 5 in Figure 1 can be directly formed at one time, without the need to first create a layer of large unevenness, and then create a layer Small bumps. Fig. 2 is a 3D image of the atomic force microscope of the surface morphology of medium carbon steel after particle shot peening. It can be seen from the figure that the surface of medium carbon steel has formed a multi-scale rough structure. Figure 3 is an image of water droplets on the surface of medium carbon steel with micro-nano multi-scale structure. After testing, the water contact angle of the surface of the medium carbon steel is 155°, which is greater than 150°, indicating that the surface has a superhydrophobic structure.

Example 2 Preparation of multi-scale structures on the surface of medium carbon steel by single-pass shot peening

1. Pretreatment: This step is the same as in Example 1 to obtain a polished surface and prepare for the construction of a rough surface structure.

2. Construction of multi-scale rough structure: Install the polished 45# medium carbon steel on the clamping table inside the shot blasting machine, and mix the projectiles with an average diameter of 150 μm and an average diameter of 50 μm at a total mass ratio of 1:1. Adjust the distance between the nozzle and the polished surface to be shot-peened to 10cm, set the shot-peening pressure to 0.3MPa, and carry out shot-peening treatment for 3 minutes. After the shot peening process is completed, the steel surface is cleaned with absolute ethanol and then dried for use.

3. Chemical modification: Soak the 45# medium carbon steel after shot peening in the n-hexane solution of perfluorododecyltrichlorosilane with a concentration of 0.2% (volume percentage) for 30 minutes, clean it with absolute ethanol and blow it. Dry. After testing, the water contact angle of the medium carbon steel surface is 151°, indicating that the surface has a superhydrophobic structure.

The above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, rather than limiting the implementation of the present invention. For those of ordinary skill in the art, other changes in various forms can be made on the basis of the above description. It is not necessary and impossible to exhaustively list all the implementation manners here. All modifications, equivalent replacements and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the claims of the present invention.

Claims (6)

1. A method for preparing a micro-nano multiscale structure on the surface of medium carbon steel, characterized in that it comprises the following specific steps: S1. First polish the surface of the medium carbon steel with 120-1000 mesh sandpaper, then polish the surface of the medium-carbon steel with a polishing agent for 5-10 minutes, and pretreat the surface of the medium-carbon steel to obtain a polished surface; S2. Using the particle shot peening process, install the medium carbon steel treated in step S1 on the clamping table inside the shot blasting machine, set the distance between the nozzle of the spray gun and the polished surface to be shot peened at 5-15 cm, and the shot peening pressure at 0.1-0.4 MPa, turn on the power supply of the shot blasting machine, and turn on the air compressor, process the medium carbon steel with particle shot peening, build a rough surface structure in situ, and dry it with cold air after cleaning; S3. Soak the medium-carbon steel treated in step S2 in a low surface energy reagent for chemical modification, wash and dry to obtain a medium-carbon steel surface with superhydrophobic properties. 2. The method for preparing the micro-nano multiscale structure on the surface of medium-carbon steel according to claim 1, wherein the polishing agent described in step S1 is a diamond suspension or a diamond polishing paste. 3. The method for preparing the micro-nano multi-scale structure on the surface of medium-carbon steel according to claim 1, characterized in that the particle projectiles described in step S2 are atomized stainless steel spherical projectiles, and the average diameter of the projectiles is 50 μm and 150 μm. 4. the preparation method of micro-nano multi-scale structure on the surface of medium carbon steel according to claim 1, characterized in that, the particle shot peening process described in step S2 is divided into any one of A or B, Among them, the A process adopts two shots of particle shot peening. First, the surface of the medium carbon steel is sprayed with projectiles with an average diameter of 150 μm for 1 to 4 minutes, and then the surface of the medium carbon steel is sprayed with projectiles with an average diameter of 50 μm. 1 to 7 minutes to obtain multi-scale surface structures; Process B adopts single-pass mixed shot peening, mixes shot peening with an average diameter of 150 μm and 50 μm at a ratio of 1:1 to 2 in total mass, and sprays the surface of medium carbon steel with the mixed shot for 1 to 7 minutes. Get multi-scale surface structures. 5. The method for preparing the micro-nano multiscale structure on the surface of medium-carbon steel according to claim 1, wherein the low surface energy reagent described in step S3 is a fluorosilane/dehydrated ethanol solution or a fluorosilane/n-hexane solution , soaking time is 10 ~ 60min. 6. The method for preparing the micro-nano multi-scale structure on the surface of medium-carbon steel according to claim 1, characterized in that the solution used for cleaning in steps S2 and S3 is absolute ethanol.