CN106399986A - Preparation method of super-hydrophobic aluminum surface with self-cleaning function - Google Patents

Abstract

The invention belongs to the technical field of surface treatment, and relates to a preparation method of a super-hydrophobic aluminum surface with a self-cleaning function. The preparation method comprises the following steps: (1) pretreatment: grinding, cleaning and drying an aluminum sample in sequence to obtain a clean sample; (2) chemical etching: putting the sample subjected to pretreatment into a chloridized molten iron solution for soaking at room temperature, then taking out the sample to clear away dirt on the surface, and drying the sample in air; and (3) surface modification: placing the sample subjected to chemical etching treatment into a low-surface-energy reagent for soaking at the room temperature for 1 to 2 h to form a layer of hydrophobic thin film on the surface of the sample, then taking out the sample, and placing the sample into a constant-temperature drying box for drying to obtain the super-hydrophobic surface. The preparation process is simple, and the raw materials are readily available; preparation of the super-hydrophobic aluminum surface with the self-cleaning function can be realized under an atmospheric environment; the contact angle for water is about 150 degrees; and the prepared super-hydrophobic aluminum surface with the self-cleaning function is good in self-cleaning and hydrophobization effect.

Description

A kind of preparation method of superhydrophobic aluminum surface with self-cleaning function

technical field

The invention belongs to the technical field of surface treatment, in particular to a method for preparing a superhydrophobic aluminum surface with a self-cleaning function.

Background technique

In the 1980s, botanists Barthlott and Neihuis of the University of Bonn in Germany found that there were micron-scale protrusions and waxy tissue structures on the surface of the lotus leaf through observation of the surface structure of the lotus leaf, which made the lotus leaf superhydrophobic (that is, water dripping It will automatically gather into water droplets and roll down on the leaf surface) which has attracted great attention worldwide. Research has found that superhydrophobic phenomena can be seen everywhere in nature. Rice leaves, shark skin, butterfly wings, water strider legs, and cicada wings all have superhydrophobic microstructure surfaces. These microstructured surfaces have special properties, such as self-cleaning, anti-adhesion, drag reduction, etc. If the excellent characteristics of super-hydrophobic surface are applied to engineering practice, the performance of materials can be greatly improved. For example, super-hydrophobic surface is used on high-rise building glass, which can realize the self-cleaning effect of rainwater erosion and reduce the loss of manpower and material resources.

Aluminum and its alloys are very important engineering metal materials. They are widely used in many fields due to their light weight, high specific strength, good thermal efficiency, easy processing and excellent corrosion resistance. Aluminum and aluminum alloys with superhydrophobic surfaces have excellent self-cleaning properties and corrosion resistance, and can be widely used in industrial fields such as automobiles, ships, construction, aerospace, and machinery manufacturing. At present, the preparation of superhydrophobic aluminum-based materials mainly adopts surface coating technology, which makes the hydrophobic performance not ideal and also has the problem of the bonding force between the substrate and the coating. Therefore, it is still necessary to develop a method for preparing superhydrophobic aluminum surfaces with low cost and simple preparation process.

At present, the preparation methods of metal-based superhydrophobic surfaces mainly include chemical etching, anodic oxidation, vapor deposition, and laser ablation. Chemical etching technology has attracted widespread attention because of its simple preparation process, good repeatability, low cost and wide adaptability. For example, the patent application number 201010521109.1 discloses a low-cost aluminum alloy super-hydrophobic surface treatment method, which uses hydrochloric acid aqueous solution to chemically etch the aluminum alloy surface, and then uses long-chain fatty acids to vapor-deposit and modify the surface of the sample by evaporation An aluminum alloy surface with good hydrophobicity is obtained. The patent application number 201610073380.0 discloses a preparation method of a superhydrophobic coating on the aluminum surface with a micro-nano composite structure. The method is to first immerse the aluminum sheet in an acid etching solution for etching, and then immerse it in a nanoparticle solution. Superhydrophobic aluminum surface with micro-nano composite structure after high-temperature treatment and silanization modification. The patent with application number 201210031621.7 discloses a method for preparing a biomimetic superhydrophobic surface of metal aluminum. The method is to soak the cleaned aluminum sheet in a certain concentration of hydrochloric acid or sodium hydroxide solution to remove oxidation on the surface of the material. layer, then hung in a mixed solution of cerium nitrate and hexamethyltetramine for chemical etching overnight, and modified with stearic acid to obtain a superhydrophobic surface with a contact angle of 150°-165°. The patent with the application number 201410667574.4 discloses a method for constructing a highly stable superhydrophobic aluminum surface. The method is to put the aluminum sheet into the sodium hydroxide solution for alkaline etching and then for the acid etching in the nitric acid solution, and then through the anodic oxidation method on the The aluminum oxide film is deposited on the surface of the aluminum sheet and then immersed in ammonia water to chemically corrode, and the superhydrophobic surface is modified by fluorosilane.

The above-mentioned preparation methods of super-hydrophobic surfaces can all obtain better super-hydrophobic effects, but there are also some problems. For example, hydrochloric acid is a dangerous chemical product. Contact with its vapor or smoke can cause acute poisoning, epistaxis, gum bleeding, etc. Ingestion can cause digestive tract burns, gastric perforation, etc. Be careful when using it. The preparation of superhydrophobic surface by coating method needs to consider the bonding force between the substrate material and the coating, and the coating is prone to peeling off when it acts on external forces. The patented processes with application numbers 201210031621.7 and 201410667574.4 are complex and costly to process, which is not conducive to mass production. Therefore, how to prepare a stable superhydrophobic self-cleaning surface by a simple and feasible method is particularly important to meet its industrial application.

Contents of the invention

In order to solve the defect of complex preparation process of superhydrophobic aluminum surface existing in the prior art, the present invention provides a method for preparing superhydrophobic aluminum surface with self-cleaning function.

In order to solve the above technical problems, the technical solution adopted in the present invention is: a method for preparing a superhydrophobic aluminum surface with self-cleaning function, the steps are as follows:

(1) Pretreatment: the aluminum sample is polished, cleaned and dried in sequence to obtain a clean sample;

(2) Chemical etching: put the pretreated sample into an aqueous solution of ferric chloride, soak it at room temperature, then take it out to remove surface dirt, and air-dry it;

(3) Surface modification: soak the chemically etched sample in a low surface energy reagent for 1 to 2 hours at room temperature to form a hydrophobic film on the surface of the sample, then take it out and dry it in a constant temperature oven to obtain Superhydrophobic aluminum surface.

Specifically, the pretreatment step described in step (1) is to grind the aluminum sample successively with 400 ^# , 1000 ^# , and 3000 ^# sandpaper, and then perform ultrasonic cleaning on the polished sample with absolute ethanol and distilled water, and ultrasonic The temperature is 40-60°C, the time is 15-30min, and then dried in a constant temperature oven at 50-80°C for 20-30min to obtain a clean sample.

Preferably, the concentration of the ferric chloride aqueous solution described in step (2) is 1.4-1.5 mol/L, and the sample is soaked in the ferric chloride aqueous solution for 30-60 min.

Further, the specific step of removing surface dirt in step (2) is to take out the sample soaked in the ferric chloride aqueous solution and put it into an ultrasonic cleaning agent, and then use absolute ethanol and distilled water to ultrasonically clean it at a constant temperature of 40-60°C 5-10min.

Preferably, the low surface energy agent described in step (3) is an ethanol solution of 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane, an ethanol solution of stearic acid, hexadecyltrimethyl One of an ethanol solution of silane, an ethanol solution of heptadecafluorodecyltrimethoxysilane, an ethanol solution of lauric acid, and an ethanol solution of palmitic acid.

Preferably, the mass percentage of the low surface energy substance in the low surface energy reagent is 1%-2%.

Preferably, the drying described in step (3) is adjusted to be dried in a constant temperature oven at 130° C. for 20-30 minutes.

Specifically, the room temperature described in step (2) and step (3) is that the air humidity is 60%-80%, and the ambient temperature is 20-26°C.

Beneficial effects: the preparation process is simple and the raw materials are easy to obtain. Using the combination of chemical etching technology and surface modification, the preparation of superhydrophobic aluminum surface with self-cleaning function can be realized in the atmospheric environment; the prepared superhydrophobic aluminum surface with self-cleaning function has a rough microstructure , the contact angle to water is about 150°; the prepared superhydrophobic aluminum surface with self-cleaning function has excellent self-cleaning and hydrophobic effects, water droplets falling on the surface of the sample will not stagnate, but will roll off quickly and Take away the dust and dirt on the surface, and at the same time reduce the contact time between the aluminum alloy substrate and water droplets, reduce corrosion and increase its performance.

Description of drawings

Fig. 1 is the microstructure figure of the superhydrophobic aluminum surface of example 1 gained;

Fig. 2 is the contact angle schematic diagram of the superhydrophobic aluminum surface of example 1 gained;

Fig. 3 is the comparative figure of ferric chloride etching sample, cupric chloride etching sample and unetched sample;

Fig. 4 is a comparison chart of the self-cleaning properties of ferric chloride etched samples, cupric chloride etched samples and unetched samples.

detailed description

In order to better understand the present invention, the technical solutions of the present invention will be further described in detail below in conjunction with examples. The experimental methods described in the following examples are conventional methods unless otherwise specified, and the reagents and materials are available from commercial sources unless otherwise specified.

Example 1

A kind of preparation method of the superhydrophobic aluminum surface with self-cleaning function of the present embodiment, comprises the steps:

(1) Pretreatment: Grind the 6061 aluminum alloy sheet with 400 ^# , 1000 ^# , and 3000 ^# sandpaper in sequence, and then ultrasonically clean the polished samples with anhydrous ethanol and distilled water at a temperature of 50°C for 20 minutes , and then dried in a constant temperature oven at 80°C for 10 minutes to obtain a clean sample;

(2) Chemical etching: put the clean sample into 1.4 mol/L ferric chloride aqueous solution, and soak for 60 min at room temperature. Take it out and put it into an ultrasonic cleaning machine, then use absolute ethanol and distilled water to ultrasonically clean at a constant temperature of 60°C for 5 minutes to remove surface dirt, and air dry;

(3) Surface modification: soak the chemically treated sample in 2% ethanol solution of 1H,1H,2H,2H-perfluorodecyltriethoxysilane for 1 hour at room temperature to form a hydrophobic layer on the surface of the sample. film, and then take it out and put it in a constant temperature oven at about 130°C to dry for 30 minutes, that is, the superhydrophobic aluminum surface with self-cleaning function is obtained.

The microstructure diagram of the superhydrophobic aluminum surface with self-cleaning function prepared in this example is shown in Figure 1, and the surface is a micron-scale rough structure.

The contact angle of the superhydrophobic aluminum surface with self-cleaning function that this example makes is as shown in Figure 2, and the contact angle with water is 149 °.

Comparative example 1

In order to form a contrast with Example 1, the ferric chloride aqueous solution of the chemical etching solution 1.4mol/L in Example 1 is replaced by the cupric chloride aqueous solution of 1.4mol/L, and the etching reaction time is replaced by 30s (via The test finds that the best reaction time for copper chloride aqueous solution to etch the aluminum alloy sample is 30s, the reaction is insufficient below 30s, and the reaction is excessive above 30s, which affects its contact angle value), and other conditions are the same as in Example 1.

By comparison it was found that:

1. When copper chloride is used as the etching solution for the reaction, the reaction is violent and the reaction rate is difficult to control; while the reaction of ferric chloride is relatively mild and the reaction rate is easy to control.

2. The contact angle of the sample etched by copper chloride is 146°, while the contact angle of the sample etched by ferric chloride is 149°, so the hydrophobicity of the sample etched by ferric chloride is better than that of copper chloride.

3. From left to right in Figure 3 are the aluminum alloy samples etched by ferric chloride, the aluminum alloy samples etched by copper chloride, and the unetched aluminum alloy samples. In order to compare the self-cleaning performance of the two methods, at room temperature, spread a layer of sand on the surface of the three samples, then drop about 10 μl of pure water, and tilt the samples at a certain angle to observe their self-cleaning conditions. Fig. 4 is a comparison chart of the self-cleaning properties of ferric chloride etched samples, cupric chloride etched samples and unetched samples. After comparison, it is found that on the surface of the sample etched by ferric chloride, the sand and soil along the road will be taken away when the water droplets roll down, and the self-cleaning property is the best. On the surface of the sample etched by copper chloride, water droplets can take away most of the dust when it rolls down, and a small part of dust remains on the surface of the sample. The self-cleaning performance of the unmodified sample surface is poor, and the dust and water are mixed together and remain on the sample surface.

4. The commercial price of copper chloride is about 4 times that of ferric chloride, and ferric chloride is more cost-effective in comparison.

Example 2

(1) Pretreatment: Grind the 6061 aluminum alloy sheet with 400 ^# , 1000 ^# , and 3000 ^# sandpaper in sequence, and then ultrasonically clean the polished samples with anhydrous ethanol and distilled water at a temperature of 40°C for 30 minutes , and then dried in a constant temperature oven at 50°C for 20 minutes to obtain a clean sample;

(2) Chemical etching: put the clean sample into a 1.5 mol/L ferric chloride aqueous solution, and soak for 30 minutes at room temperature. Take it out and put it into an ultrasonic cleaning machine, then use absolute ethanol and distilled water to ultrasonically clean at a constant temperature of 40°C for 10 minutes to remove surface dirt, and air dry;

(3) Surface modification: soak the chemically treated sample in 1% ethanol solution of heptadecafluorodecyltrimethoxysilane for 2 hours at room temperature to form a hydrophobic film on the surface of the sample, then take it out and put it in 130 ℃ in a constant temperature oven for 20 minutes to obtain the superhydrophobic aluminum surface with self-cleaning function. The contact angle of the finally prepared sample with water was 148° after testing.

Claims (8)

1. a kind of preparation method on the Super-hydrophobic aluminium surface with self-cleaning function it is characterised in that：Step is as follows：

(1) pretreatment：Aluminum sample is obtained successively after polishing, clean, being dried the sample of cleaning；

(2) chemical etching：Sample after pretreatment is put in ferric chloride in aqueous solution, soaks at room temperature, further take out removing Surface contaminants, and air-dry；

(3) surface modification：Sample after chemical etching is processed is placed in low-surface-energy reagent and soaks 1～2h at room temperature, makes Sample surfaces form one layer of hydrophobic film, then take out and put into dry in constant temperature oven, i.e. prepared Super-hydrophobic aluminium surface.

2. the Super-hydrophobic aluminium surface with self-cleaning function according to claim 1 preparation method it is characterised in that：Step Suddenly the pre-treatment step described in (1) is specially aluminum sample successively through 400^#、1000^#、3000^#Sand papering, after grinding process Sample carry out ultrasound wave with dehydrated alcohol and distilled water successively again and clean, ultrasonic temperature is 40～60 DEG C, the time is 15～ 30min, then 20～30min is dried in 50～80 DEG C of constant temperature ovens, obtain the sample of cleaning.

3. the Super-hydrophobic aluminium surface with self-cleaning function according to claim 1 preparation method it is characterised in that：Step Suddenly the concentration of the ferric chloride in aqueous solution described in (2) is 1.4～1.5mol/L, and sample soaks 30- in ferric chloride in aqueous solution 60min.

4. the preparation method on the Super-hydrophobic aluminium surface with self-cleaning function according to claim 1 or 3, its feature exists In：Removing surface contaminants described in step (2) concretely comprise the following steps, and the sample taking-up after immersion ferric chloride in aqueous solution are put into ultrasonic It is cleaned by ultrasonic 5-10min with dehydrated alcohol, distilled water under 40-60 DEG C of constant temperature successively in ripple abluent.

5. the Super-hydrophobic aluminium surface with self-cleaning function according to claim 1 preparation method it is characterised in that：Step Suddenly the low-surface-energy reagent described in (3) is 1H, the ethanol solution of 1H, 2H, 2H- perfluoro decyl triethoxysilane, stearic Ethanol solution, the ethanol solution of cetyl trimethyl silane, the ethanol solution of 17 fluorine decyl trimethoxy silanes, lauric acid Ethanol solution and Palmic acid one of ethanol solution.

6. there is the preparation method on the Super-hydrophobic aluminium surface of self-cleaning function according to claim 1 or 5, its feature exists In：The mass percent of the low-surface energy substance in described low-surface-energy reagent is 1%-2%.

7. the Super-hydrophobic aluminium surface with self-cleaning function according to claim 1 preparation method it is characterised in that：Step Suddenly the drying described in (3) is adjusted to 20-30min be dried in 130 DEG C of constant temperature oven.

8. the Super-hydrophobic aluminium surface with self-cleaning function according to claim 1 preparation method it is characterised in that：Step Suddenly (2) and the room temperature described in step (3) are 60%-80% for air humidity, and ambient temperature is 20-26 DEG C.