CN106048665A - Method for preparing metal-base super-oleophobic composite casting layer by using hot compression deformation process - Google Patents

Abstract

The invention discloses a method for preparing a metal-based super-oleophobic composite casting layer by using a hot pressing deformation method. It is easier to obtain a dense and smooth composite casting layer by using a composite electroforming process under appropriate pulse electric parameters; different polymers can be selected. Particle size, controlling the temperature of the hot plate and the size of the pressure to obtain a structure with different concave curvatures, thereby obtaining a workpiece surface with controllable oleophobicity; the technology and equipment used in this invention are simple and low-cost, and are suitable for large-area metal surfaces. Oil modified.

Description

A method for preparing metal-based super-oleophobic composite casting layer by hot pressing deformation method

technical field

The invention relates to a method for preparing a metal-based super-oleophobic composite casting layer by a hot-pressing deformation method, which is used for changing the wettability of the metal surface to make it have super-oleophobic properties. The method is suitable for the preparation of large-area super-oleophobic surfaces, has low preparation cost and is easy to realize, and belongs to the field of electrochemical deposition.

Background technique

Wetting is a phenomenon in which a solid interface changes from a solid-gas interface to a solid-liquid interface. Wettability refers to the ability or propensity of a liquid to spread on a solid surface. Wettability is a common phenomenon in nature. For example, the phenomenon that rainwater falls on the surface of lotus leaves to form spherical droplets and rolls down, and the self-cleaning effect of lotus leaves "out of silt without staining", which is the phenomenon of superhydrophobicity. In addition, many animals and plants, such as the feet of water striders, the wings of butterflies, and rice leaves, also have superhydrophobic properties. Studies have shown that the superhydrophobic properties of all these surfaces are due to the combined action of micro-nano rough structures and low surface energy substances.

Wettability is also an important aspect in the fields of material science and surface engineering, and has many important applications in daily life, industrial production, and agricultural production. The so-called superhydrophobic means that the static contact angle of water droplets on the solid surface exceeds 150°. Similarly, superoleophobic means that the static contact angle of oil droplets on the solid surface exceeds 150°. However, the surface tension of oil droplets is much smaller than that of water droplets. Therefore, it is more difficult to prepare a solid surface with superoleophobic properties than a superhydrophobic surface. Relevant studies have shown that in addition to the modification of low surface energy molecules to prepare super-oleophobic surfaces in air, it is necessary to introduce concave surface curvature on the surface with micro-nano rough structure, so that the micro-nano rough structure is concave or cantilevered. This poses greater challenges to the manufacturing process.

At present, a large number of literatures have reported artificial bionic superhydrophobic surfaces. These materials have a wide range of applications in surface self-cleaning, anti-icing, anti-fog, anti-pollution, anti-corrosion, and fluid drag reduction. There are relatively few reports on oleophobic surfaces, but super-oleophobic surfaces have huge application space in industrial and agricultural production, such as oil-repellent coatings, seawater antifouling treatment, oil pipeline anti-oil crawling, and oil-water separation. Metal materials are widely used in engineering, and they are widely used. However, the anti-pollution and anti-corrosion properties of metals are poor, so it is of great significance to prepare surfaces with super-oleophobic properties on metals.

The so-called surface texture refers to an array of patterns such as pits, dents or convex hulls of a certain size and arrangement on the surface of an object. Surfaces with micro- and nano-scale micro-textures have completely different characteristics from smooth surfaces in terms of surface energy, optical properties, bionic properties, mechanical properties, hydrodynamic properties, and friction and wear properties. dynamism and show great application potential in many engineering fields.

Fabrication methods of oleophobic surfaces usually follow bottom-up or top-down approaches. The existing methods for preparing super-oleophobic surfaces are generally as follows: (1) Template-free wet etching (2) Femtosecond laser etching (3) Electrospinning (4) Electrodeposition (5) Sol-gel method, etc.

The prior art mainly has the following disadvantages: (1) template-free wet etching can etch the surface of silicon and polymers, which has high efficiency and low cost, but the controllability of the etched surface morphology is poor. This method is easy to obtain a super-hydrophobic surface, but It is not easy to obtain a superoleophobic surface. The oleophobic surface can be obtained by Bosch etching method, but the process is complicated and the cost is high; (2) femtosecond laser etching method can prepare micro-nano nested structure surface with high precision and regular shape, but the process efficiency is low and it is not It is suitable for large-scale manufacturing, and the equipment is extremely expensive; (3) The electrospinning method can prepare superhydrophobic materials in a large area by using micro/nano filaments to construct rough structures on the surface, but the surface microstructure of the prepared superhydrophobic materials can be limited. Poor controllability and uniformity, poor wear resistance, and short service life; (4) Ordinary electrodeposition methods can deposit metals or polymers, which can efficiently and conveniently prepare surfaces with micro-nano rough structures, but the morphology is highly random , it is not easy to control, and it is not easy to produce a concave or cantilever secondary groove structure.

Contents of the invention

In view of the shortcomings of the above-mentioned prior art, the purpose of the present invention is to propose a process for preparing metal-based super-oleophobic composite casting layer by hot pressing deformation method, which is an improvement of ordinary electrodeposition method, and can produce concave shape with controllable shape Or the secondary groove structure of the cantilever.

According to one aspect of the present invention, propose a kind of method that utilizes hot-press deformation method to prepare metal-based super-oleophobic composite cast layer, comprise the following steps: (1) use the metal substrate through degreasing and decontamination as electroforming cathode, nickel plate As the anode is connected to the power supply, the electroforming system is constituted by a nickel-based electroforming solution dispersed with microparticle balls of polymer materials between the anode and the cathode, and the electroforming system is energized so that the polymer microparticle balls and nickel ions in the electroforming solution are deposited on the metal Co-deposit on the surface of the substrate to form a nickel-based dispersed composite electroforming layer with a thickness of about 50-80um; (2) After the electrodeposition is completed, the metal substrate deposited with the electroforming layer is used as an anode for electrolysis to remove the extremely thin electroforming layer on the surface. One layer of nickel metal, so that the dispersed polymer microparticle spheres that are exposed are used as the asperity structure; (3) the height of the asperities on the surface of the workpiece is ground to substantially the same by a precision grinder through the electrolytically processed workpiece; ( 4) Heat a smooth and flat platen to the vicinity of the melting point of the selected polymer material, maintain the temperature and place it on the asperities on the surface of the prepared workpiece, and make the asperities abnormal by applying a certain pressure. Evenly deformed, after deformation, the part close to the surface of the high-temperature press plate becomes wider, while other parts only change slightly, and a super-oleophobic concave structure on the surface with an opening smaller than the inner cavity is obtained; (5) Finally, the workpiece and the surface dripped with fluorosilane The carrier sheets are placed together in a closed container for baking, so that fluorosilane forms a nano-thin layer of low surface energy substances on the surface of the workpiece through adsorption, and finally makes the metal surface achieve super oleophobic performance.

According to one aspect of the present invention, the material of the microparticle ball is a thermoplastic polymer (such as low-density polyethylene, PMMA, etc.), which is deformed by heat and pressure, and then cooled and shaped.

According to one aspect of the present invention, the material selection and particle size (20-30um) of the micro-particles must be consistent, and its volume fraction in the electroforming layer is controlled within the range of 40-60%. If the volume fraction is too small, the micro-spheres will be distributed poorly If the spacing is too large, the volume fraction will affect the formation of the casting layer. Match the appropriate particle size and volume fraction to facilitate the formation of a surface super-oleophobic concave structure with an opening smaller than the inner cavity in the subsequent process.

According to one aspect of the present invention, non-uniform thermal deformation occurs on the asperity surface, and when the common asperity surface of the thermoplastic material is in contact with a high-temperature smooth and flat surface, the thermoplastic material near the high-temperature surface is in a state of higher temperature, Its fluidity and deformability are good, while the temperature of the thermoplastic polymer away from the high-temperature surface is low, and its fluidity and deformability are poor. Therefore, it can be pressurized to form a surface super-oleophobic concave structure with an opening smaller than the inner cavity.

According to one aspect of the present invention, in step (2), an appropriate amount of surfactant is added to the electroforming solution, and they can be adsorbed in large quantities on the surface of micro-nano particle spheres to form a firm adsorption film.

According to one aspect of the present invention, the asperities in step (5) are press-molded into a surface superoleophobic concave structure with an opening smaller than the inner cavity.

Description of drawings

Fig. 1 is a process flow diagram of the present invention;

Fig. 2 is a superoleophobic concave structure diagram of the present invention.

detailed description

Embodiments of the present invention are described in detail below, examples of which are illustrated in the drawings, wherein like or similar reference numerals designate like or similar functional elements throughout. The embodiments described below by referring to the figures are exemplary only for explaining the present invention and should not be construed as limiting the present invention. On the contrary, the embodiments of the present invention include all changes, modifications and equivalents coming within the spirit and scope of the appended claims.

As shown in Figure 1, a method for preparing a metal-based super-oleophobic composite cast layer by hot pressing deformation method is as follows:

S1. Pretreatment of metal substrate 1: After soaking metal substrate 1 in hot alkali solution to remove oil, rinse it with acetone and deionized water, and dehydrate it in a vacuum drying oven at 120°C for 15 minutes to remove impurities and make the texture and metal Base 1 is firmly connected.

S2. Surface dispersion composite electroforming of the metal substrate 1: use the nickel plate 2 as the anode, and the metal substrate 1 as the cathode, both of which are respectively connected to the positive and negative electrodes of the power supply 5, and a polymer material is dispersedly distributed between the anode and the cathode The nickel-based electroforming solution 4 of the microparticle ball 3 constitutes an electroforming system. After electrification, a reduction reaction occurs at the cathode, so that the polymer microparticles 3 and nickel ions in the electroforming solution 4 are co-deposited on the surface of the metal substrate 1 to form a nickel-based dispersed composite electroforming layer 6 with a thickness of about 50-80um;

In this step, electrical parameters: square wave pulse with current density of ^0.5-5A /dm2, frequency of 0.5-3KHz, duty cycle of 20-80%, processing time (depending on the thickness of the cast layer), etc.; electroforming solution formula : Ni(CH ₂ SO ₃ ) ₂ 4H ₂ O—200~500g/L, NiCl ₂ 6H ₂ O—15~30g/L, H ₃ BO ₃ —30~45g/L, pH value about 4, temperature About 50°C and so on.

S3. Electrolysis of the nickel-based dispersed composite electroforming layer: After the electroforming is completed, the cathode and anode of the electroforming system are reversed, and the metal substrate 1 deposited with the electroforming layer 6 is used as the anode for electrolysis. After energization, an oxidation reaction occurs at the anode, and an extremely thin layer of nickel metal on the surface of the electroformed layer 6 is removed, so that the dispersedly distributed polymer microparticle balls 3 themselves appear as asperities 7 .

In this step, the removal thickness of the nickel metal layer (about the size of the particle ball radius) is controlled by controlling the electrical parameters: direct current with a current density of 10-15A/dm ² , and processing time (depending on the removal thickness). If the removal thickness is too large, the particle balls will easily fall off from the casting layer, and if the removal thickness is too small, it will be difficult to form the asperities 7 required in the subsequent process.

S4. Grinding the asperities: take out the electrolytically processed workpiece and clean it with deionized water, use a precision grinder to grind the asperities 7 on the surface of the workpiece to the same height, then clean them with deionized water and dry them with nitrogen .

S5. Hot pressing deformation: heat up a smooth and straight pressing plate 8 to near the melting point of the selected polymer material, keep the temperature and place it on the asperity 7 on the surface of the prepared workpiece, pass through the asperity 7 The method of applying pressure (10Pa<P<5000Pa) between the surface and the surface of the high-temperature press plate 8 causes the asperity 7 to deform non-uniformly. After deformation, the part close to the surface of the high-temperature press plate 8 becomes wider, while other parts only change slightly. Keep the pressure and temperature for a certain period of time (5-10s after pressurization), then separate the high-temperature press plate 8, and cool it to room temperature at a cooling rate of 2-5°C/min. The surface of the cavity has a super-oleophobic concave structure 9 .

S6. Low surface energy modification: put the electrolytically processed workpiece and the carrier sheet dripped with fluorosilane 10 together in a closed container, then bake in an oven at 65°C for 1 hour, take it out and put it at room temperature to complete the preparation of the workpiece . During the baking process, fluorosilane 10 will form a nano-thin layer of low surface energy substances on the surface of the workpiece through adsorption, so that the metal surface can achieve super oleophobic properties.

The finished workpiece is shown in Figure 2.

More preferably, in step S1, the metal substrate 1 with a flat and smooth surface can be cleaned with an ultrasonic cleaner filled with ethanol solution, and then use a surfactant to remove the oxide layer on the metal surface, and finally clean it with deionized water and place it in an oven Dry on medium to remove surface moisture. The surface of the metal base 1 is clean and free from impurities and no oxide layer, so that the metal layer deposited on the surface has a strong bonding force with the metal base.

More preferably, in step S2, an appropriate amount of surfactant is added to the electroforming solution, and they can be adsorbed in large quantities on the surface of the micro-nano particle spheres to form a firm adsorption film, which can effectively prevent the agglomeration of the micro-nano particles and The casting system is supplemented by ultrasonic or electromagnetic vibration stirring, which can improve the particle suspension effect more than pure mechanical stirring.

Compared with the prior art, the present invention has the following advantages: 1) it is easier to obtain a compact and smooth composite casting layer by using the composite electroforming process under suitable pulse electric parameters; The temperature of the hot plate and the size of the pressure can obtain a structure with different concave curvatures, thereby obtaining a workpiece surface with controllable oleophobicity; 3) The technology and equipment used in this invention are simple and low in cost, and are suitable for superoleophobic modification of large-area metal surfaces .

The present invention may be embodied in other specific forms without departing from the spirit or essential characteristics of the inventions. The aspects of the specific embodiments should be considered as illustrative only and not restrictive. Accordingly, the scope of the invention is indicated by the appended claims rather than by the foregoing description. All changes that fall within the equivalent meaning and scope of the scope of the patent application shall be deemed to fall within the scope of the patent application.

Claims (7)

1. the method utilizing hot compression deformation method to prepare the superoleophobic compound cast layer of Metal Substrate, comprises the steps: that (1) will be passed through The metallic substrates of deoiling connects power supply as electroforming negative electrode, nickel plate as anode, passes to disperse between the anode and cathode The Ni-based electroforming solution of the microparticle ball that polymeric material is distributed constitutes electroforming system, and energising makes polymer micropellet in electroforming solution Ball and nickel ion form, at metal substrate surface codeposition, the Ni-based disperse composite electroforming deposit that thickness is about 50～80um；(2) electricity The metallic substrates that deposition has after having deposited electroformed layer is electrolysed as anode, removes very thin on electroformed layer surface one layer Nickel metal so that the polymer micropellet ball of the Dispersed precipitate revealed self is as micro-bulge structure；(3) will be through electrolysis The height of surface of the work micro-bulge is milled to basically identical by the workpiece precision grinder of processing；(4) by a smooth straight pressing plate It is warming up near the fusing point of selected polymeric material, keeps this temperature and be placed on the surface of the work micro-bulge prepared On, by the way of applying certain pressure, make micro-bulge generation heterogeneous deformation, near the position of high temperature clamp surface after deformation Broaden, and other positions only occur the least change, obtain the opening superoleophobic concave inward structure in surface less than inner chamber；(5) last By workpiece with drip and have the carrying tablet of silicon fluoride to be collectively disposed in hermetic container to carry out baking and make silicon fluoride pass through adsorption in work Part surface forms the low-surface energy substance of one layer of nano thin-layer, finally makes metal surface reach superoleophobic performance.

Utilizing the method that hot compression deformation method prepares the superoleophobic compound cast layer of Metal Substrate the most as claimed in claim 1, its feature exists In, the material of described polymer micropellet ball is thermoplastic polymer.

Utilizing the method that hot compression deformation method prepares the superoleophobic compound cast layer of Metal Substrate the most as claimed in claim 1, its feature exists In, the material of described polymer micropellet ball is Low Density Polyethylene or PMMA.

Utilizing the method that hot compression deformation method prepares the superoleophobic compound cast layer of Metal Substrate the most as claimed in claim 1, its feature exists In, the selection of described polymer micropellet ball must be consistent with particle diameter, and its size is 20～30um, and it is volume in electroformed layer Fractional domination is in the range of 40～60%.

Utilizing the method that hot compression deformation method prepares the superoleophobic compound cast layer of Metal Substrate the most as claimed in claim 1, its feature exists In, in step (1), the metallic substrates smooth to surfacing can be carried out clearly with the ultrasonic washing unit filling ethanol solution Wash, recycle removal of surfactant oxidation on metal surface layer, finally clean with deionized water to be placed in baking oven drying and remove Surface moisture.

Utilizing the method that hot compression deformation method prepares the superoleophobic compound cast layer of Metal Substrate the most as claimed in claim 1, its feature exists In, in step (2), electroforming solution adding appropriate surfactant, they can adsorb in large quantities at micro-nano particle ball Surface forms one layer of firm adsorbed film.

Utilizing the method that hot compression deformation method prepares the superoleophobic compound cast layer of Metal Substrate the most as claimed in claim 1, its feature exists In, the micro-bulge extrusion forming opening of step (5) is less than the superoleophobic concave inward structure in surface of inner chamber.