KR20200093199A - Method for superhydrophobic surface of the outer panel or component for heat exchanger - Google Patents

Abstract

The present invention relates to a superhydrophobic method for a surface of an outer panel or a component for a heat exchanger. The method for hydrophobic-treats a surface of an outer panel or a component of an aluminum alloy for a heat exchanger of the present invention implements a shape, a diameter and a density of a blow hole of an anodized aluminum layer formed on an aluminum alloy surface through anodized voltage and time control in various shapes such as a pillar-on-pore, thereby having an economic effect in which the aluminum alloy having a controlled three-dimensional anodized thin film structure can be manufactured at a low cost within a short time. The aluminum alloy having the controlled anodized thin film structure manufactured by the method can have excellent superhydrophobic properties, corrosion resistance and heat conductivity to be used as the outer panel or the component of the heat exchanger.

Description

Method for superhydrophobic surface of the outer panel or component for heat exchanger

The present invention relates to a method for superhydrophobicizing the surface of an outer plate or component for a heat exchanger, and more particularly, to a method of treating the surface of an aluminum alloy outer plate or component for a heat exchanger with hydrophobicity.

Aluminum oxide coatings with nano-sized pores arranged in a regular hexagonal structure have been used for nanotechnology, such as carbon nanotubes, nanowires, etc., using aluminum anodic oxidation processes due to recent application expansion since they were first researched and reported in 1995. In addition, various nanotechnology researches are actively being conducted.

The pore diameter (D _P ) of the aluminum anodized film and the interpore distance (D _int ) are important elements for nanotechnology such as photovoltaic devices such as solar cells, LEDs, and metal nanowires. It has a direct impact on performance in related applications and devices.

Electrochemical anodizing processes have been used for surface treatment of metallic materials for over 70 years. The nanostructures produced through the anodization process can realize nanostructures with less budget and time compared to expensive electronic lithography or semiconductor etching processes using silicon. However, this anodized film has a two-dimensional porous arrangement that can only control the side dimensions.

In addition, in the production of a regularly arranged anodized aluminum film having adjusted the type and concentration of the acid electrolyte of an aluminum alloy, many studies and techniques have been developed, such as the hydroxyl method, the sulfuric acid method, and the phosphoric acid method, but the change in the type and concentration of the acid electrolyte The anodization process by is limited in the increase in the diameter of the pores and the gap between the pores and the pores, and this technique is also possible only in the production of a two-dimensional porous anodized film.

The pillar-on-pore (POP) structure, which is a structure in which a sharp pillar at the top of the pore is formed in a single or bundle form, has a higher contact angle than a conventional flat hexagonal porous surface ( It has a contact angle and a low contact angle hysteresis, and thus has excellent superhydrophobic properties. In addition, the pillar-on-pore structure has the characteristics of hydrodynamic drag reduction, anticorrosion, antibiofouling, and anti-icing, thus realizing the surface of smartphones, home appliances, etc. It can play a big role. However, a technique for forming such a pillar-on-pore structure on a semiconductor or a high-purity aluminum substrate has been studied, but it is very difficult to form on an alloy and has not been studied. In general, many studies have been conducted on a technique for manufacturing a structure having a porous array of three-dimensional shape from a high-purity aluminum substrate, but in the actual industry, it is used in an alloy form rather than a high-purity aluminum substrate. When the technique studied as is applied to an aluminum alloy used for actual commercialization, there is a problem that formation control is difficult to reproduce in the same way.

On the other hand, the heat exchanger is a device that exchanges heat between two fluids having different temperatures and humidity, which is made of a stacked structure of heat exchange elements, and passes two fluids with different temperatures and humidity alternately to exchange heat and exchange moisture through temperature differences. It is structured to perform latent heat exchange. At this time, the heat exchange is performed by conduction in the heat exchange element and convection between fluids adjacent to the heat exchange element, and until recently, copper heat exchangers using copper as a heat exchange element occupy most of the heat exchanger market due to excellent heat conductivity. However, due to advantages such as light weight, ease of supply and demand, and heat exchange performance corresponding to copper heat exchangers, the demand for aluminum heat exchangers is rapidly increasing based on the market of automobiles and home appliances (air-conditioners, refrigerators, outdoor units, dehumidifiers). .

When an aluminum heat exchanger is used for cooling, moisture contained in the air condenses on the surface of the heat exchanger to form small droplets, and these droplets increase the air resistance of the heat exchanger, thereby lowering the heat transfer coefficient due to convection, thereby rapidly increasing the heat exchange efficiency. Lowers. In addition, condensed water droplets over time cause corrosion of aluminum in the heat exchanger, and fine white powder such as aluminum oxide is generated on the heat exchanger surface. Accordingly, there is a need to develop a material having improved superhydrophobicity (superhydrophobicity) along with a treatment method for improving corrosion resistance.

Accordingly, the present applicant solves the above-described conventional problems, and a method of manufacturing an aluminum alloy coating for a heat exchanger plate or component having a porous arrangement of three-dimensional shape and a method of forming a pillar-on-pore structure on the alloy In order to develop, a pre-patterned aluminum alloy is subjected to the secondary and tertiary anodization processes by adjusting the anodization voltage, thereby producing a porous film having a three-dimensional shape with various structures such as pillar-on-pore. Thus, the present invention was completed.

Korean Registered Patent No. 10-0935964

An object of the present invention is to provide a method of treating the surface of an aluminum alloy outer plate or component for heat exchangers with hydrophobicity.

Another object of the present invention is to provide an aluminum alloy shell or part for a heat exchanger having a hydrophobic surface produced by the above method.

Another object of the present invention is to provide a method for forming an anodized film having a pillar-on-pore structure on the surface of an aluminum alloy outer plate or component for a heat exchanger.

Another object of the present invention is to provide an aluminum alloy shell or component for a heat exchanger having a hydrophobic surface of a pillar-on-pore structure produced by the above method.

In order to achieve the above object,

The present invention is a pre-patterning step of removing the primary anodized film by etching after first anodizing an aluminum alloy for a heat exchanger plate or component at 30-50 V for 5-15 hours. (Step 1); A second anodizing treatment of the aluminum alloy pre-patterned in step 1 (step 2); Pore widening the second anodized aluminum alloy in step 2 (step 3); And a third anodization treatment of the aluminum alloy having the pore expansion completed in step 3 (step 4); the second anodization of step 2 and the third anodization of step 4 are 20-50V, respectively. Soft anodizing conditions for anodizing for 10-50 minutes at; And hard anodizing conditions for anodizing at 60-90 V for 10-50 seconds; It provides a method of treating the surface of the aluminum alloy outer plate or component for heat exchangers with a hydrophobic property, characterized in that anodizing treatment is performed using any one of the conditions.

In addition, the present invention provides an aluminum alloy outer plate or component for a heat exchanger having a hydrophobic surface produced by the above method.

Furthermore, the present invention is a pre-patterning that removes the primary anodized film by etching the primary anodization for 5-15 hours at 30-50V for an aluminum alloy for a shell or component of a heat exchanger. ) Step (step 1); A second anodizing treatment of the aluminum alloy pre-patterned in step 1 (step 2); In step 2, the second anodized aluminum alloy is immersed in a solution of 0.01-10M phosphoric acid (H ₃ PO ₄ ) for 55-65 minutes to pore widening (step 3); And a third anodization treatment of the aluminum alloy having the pore expansion completed in step 3 (step 4), wherein the second anodization in step 2 and the third anodization in step 4 are 70-90V, respectively. Anodic oxidation using hard anodizing conditions for 20-40 seconds in the anodizing process, characterized in that the aluminum alloy shell for heat exchangers or pillar-on-pore on the surface of parts ) Provides a method of forming an anodized film having a structure.

Furthermore, the present invention provides an aluminum alloy shell or component for a heat exchanger having a hydrophobic surface of a pillar-on-pore structure produced by the above method.

The method of hydrophobically treating the surface of an aluminum alloy outer plate or component for a heat exchanger of the present invention provides a pore shape, diameter, and density of an anodized aluminum layer formed on an aluminum alloy surface through anodization voltage and time control. By implementing in various forms such as pores, an aluminum alloy having a three-dimensionally shaped anodized film structure controlled aluminum alloy has an economical effect that can be produced in a short time at a low cost, and the anodized film structure controlled by the above method is controlled aluminum alloy. Since it has excellent superhydrophobicity, corrosion resistance, and thermal conductivity, it can be used for heat exchanger outer plate or component applications.

1 is a scanning electron microscope photographing a three-dimensional structure of a top view and a cross view of an aluminum alloy anodized film formed on the pre-patterned aluminum alloy surfaces of Examples 1 to 4 according to the present invention ( SEM) image; At this time, MA was performed for 30 minutes at 40 V, HA for 30 seconds at 80 V, and PW for 30 minutes at 30° C. The scale bars of the surface and the cross-section were 200 nm and 1 μm, respectively.
FIG. 2 is a scanning electron microscope photographing a three-dimensional structure of a top view and a cross view of an aluminum alloy anodized film formed on the pre-patterned aluminum alloy surface of Examples 5 to 8 according to the present invention ( SEM) image; At this time, MA was performed at 40 V for 30 minutes, HA at 80 V for 30 seconds, and PW at 30°C for 40 minutes, and the surface and cross-sectional scale bars were 200 nm and 1 μm, respectively.
3 is a scanning electron microscope photographing a three-dimensional structure of a top view and a cross view of an aluminum alloy anodized film formed on the pre-patterned aluminum alloy surfaces of Examples 9 to 12 according to the present invention ( SEM) image; At this time, MA was performed at 40 V for 30 minutes, HA at 80 V for 30 seconds, and PW at 30°C for 50 minutes, and the surface and cross-sectional scale bars were 200 nm and 1 μm, respectively.
4 is a scanning electron microscope photographing a three-dimensional structure of a top view and a cross view of an aluminum alloy anodized film formed on the pre-patterned aluminum alloy surfaces of Examples 13 to 16 according to the present invention. SEM) image; At this time, MA was performed at 40 V for 30 minutes, HA at 80 V for 30 seconds, and PW at 30° C. for 60 minutes, and the surface and cross-sectional scale bars were 200 nm and 1 μm, respectively.
5 is an image showing the results of measuring the contact angle for water droplets after FDTS coating on the aluminum alloy anodized film formed on the pre-patterned aluminum alloy surfaces of Examples 1 to 4 according to the present invention; (a) Control (control), (b) Example 1 (MA→PW→MA), (c) Example 2 (MA→PW→HA), (d) Example 3 (HA→PW→MA) and (e) Example 4 (HA→PW→HA).
Figure 6 is an image showing the results of measuring the contact angle for water droplets after FDTS coating on the aluminum alloy anodized film formed on the pre-patterned aluminum alloy surface of Examples 5 to 8 according to the present invention; (a) Control (control), (b) Example 5 (MA→PW→MA), (c) Example 6 (MA→PW→HA), (d) Example 7 (HA→PW→MA) and (e) Example 8 (HA→PW→HA).
7 is an image showing the results of measuring the contact angle for water droplets after FDTS coating on the aluminum alloy anodized film formed on the pre-patterned aluminum alloy surfaces of Examples 9 to 12 according to the present invention; (a) Control (control), (b) Example 9 (MA→PW→MA), (c) Example 10 (MA→PW→HA), (d) Example 11 (HA→PW→MA) and (e) Example 12 (HA→PW→HA).
8 is an image showing the results of measuring the contact angle for water droplets after FDTS coating on the aluminum alloy anodized film formed on the pre-patterned aluminum alloy surface of Examples 13 to 16 according to the present invention; (a) Control (control), (b) Example 13 (MA→PW→MA), (c) Example 14 (MA→PW→HA), (d) Example 15 (HA→PW→MA) and (e) Example 16 (HA→PW→HA).

Hereinafter, the present invention will be described in detail.

Method for treating the surface of aluminum alloy shell or parts for heat exchangers with hydrophobicity

The present invention is a pre-patterning step of removing the primary anodized film by etching after first anodizing an aluminum alloy for a heat exchanger plate or component at 30-50 V for 5-15 hours. (Step 1);

A second anodizing treatment of the aluminum alloy pre-patterned in step 1 (step 2);

Pore widening the second anodized aluminum alloy in step 2 (step 3); And

In the step 3, the third step of anodizing the aluminum alloy having the pore expansion completed (step 4); includes,

The secondary anodization in step 2 and the tertiary anodization in step 4 are respectively mild anodizing conditions for anodizing at 20-50V for 10-50 minutes; And hard anodizing conditions for anodizing at 60-90 V for 10-50 seconds; Characterized in that the anodizing treatment using any one of the conditions,

Provided is a method of treating the surface of an aluminum alloy outer plate or component for a heat exchanger with hydrophobicity.

In general, when a water droplet comes into contact with a solid surface, it is defined as hydrophobic when the contact angle of the water droplet falls within a range of 120 to 150°, and when the contact angle is 150° or more, super hydrophobic, 170 Above °, it is defined as ultra super hydrophobic.

In the method of hydrophobically treating the surface of an aluminum alloy outer plate or a component for a heat exchanger according to the present invention, the pore expansion in step 3 is performed by performing a second anodizing treatment in step 2 of the aluminum alloy to 0.01-10M phosphoric acid (H ₃ PO ₄ ) may be immersed in the solution for 20-70 minutes. Preferably it may be immersed in a 0.01-1.0M phosphoric acid solution for 45-65 minutes, more preferably it may be immersed in a 0.05-0.5M phosphoric acid solution for 55-65 minutes, even more preferably 0.08- It may be immersed in 0.2M phosphoric acid solution for 58-62 minutes.

In the method of hydrophobically treating the surface of an aluminum alloy outer plate or component for a heat exchanger according to the present invention, a secondary anodized aluminum layer is formed by the secondary anodization, and tertiary anodization by the tertiary anodization. An aluminum layer can be formed. At this time, the secondary anodized aluminum layer region by secondary anodization is formed on the outer side away from the aluminum alloy surface, and the tertiary anodized aluminum layer region by tertiary anodization is formed on the inner side closer to the aluminum alloy surface. It can be.

According to an embodiment of the present invention, the secondary anodization of step 2 is hard anodized for 20-40 seconds at 70-90V, and the pore expansion in step 3 is 0.01-10M phosphoric acid (H ₃ PO ₄ ). The solution is immersed in a solution for 45-65 minutes, and the tertiary anodization of step 4 may be a hard anodizing treatment at 70-90V for 20-40 seconds, preferably, the secondary anodization of step 2 is Hard anodized for 20-40 seconds at 70-90 V, and the pore expansion in step 3 was immersed in a solution of 0.01-5.0M phosphoric acid (H ₃ PO ₄ ) for 55-65 minutes, and the tertiary anode in step 4 The oxidation may be a hard anodizing treatment at 70-90V for 20-40 seconds, more preferably the secondary anodization of step 2 is hard anodizing treatment at 75-85V for 25-35 seconds, and the above step The pore expansion of 3 is immersed in a solution of 0.05-1.0M phosphoric acid (H ₃ PO ₄ ) for 55-65 minutes, and the tertiary anodization of step 4 is hard anodization at 25-35 seconds at 75-85V. More preferably, the secondary anodization of step 2 is hard anodized at 78-82V for 28-32 seconds, and the pore expansion in step 3 is 0.05-0.5M phosphoric acid (H ₃ PO ₄ ). The solution is immersed in the solution for 28-32 minutes, and the third anodization of step 4 may be a hard anodization treatment at 78-82V for 28-32 seconds.

In the method of hydrophobically treating the surface of an aluminum alloy outer plate or component for a heat exchanger according to the present invention, the pore diameter of the three-dimensional shape of the anodic aluminum oxide layer formed on the aluminum alloy surface and Hydrophobicity may be expressed by controlling any one or more of the pore and the interpore distance.

In the method of hydrophobically treating the surface of an aluminum alloy outer plate or component for a heat exchanger according to the present invention, the three-dimensional shape anodized aluminum layer formed on the surface of the aluminum alloy outer plate or component for a heat exchanger is a pillar-on-pore ( It may have a pillar-on-pore structure.

In the method of hydrophobically treating the surface of an aluminum alloy outer plate or component for a heat exchanger according to the present invention, the anodized film structure control of the aluminum alloy surface has a pore diameter of the secondary anodized aluminum layer of the tertiary anodized aluminum layer. It may be to control to be a hierarchical structure larger than the pore diameter.

In the method of treating the surface of an aluminum alloy outer plate or component for a heat exchanger according to the present invention with hydrophobicity, the electrolyte solution comprising primary anodization in step 1, secondary anodization in step 2 and tertiary anodization in step 3 is Sulfuric acid (H ₂ SO ₄ ), phosphoric acid (H ₃ PO ₄ ), oxalic acid (C ₂ H2O ₄ ), chromic acid, hydrofluoric acid, and potassium hydrogen phosphate, respectively. dipotassium phosphate, K ₂ HPO ₄ ), or any one of these mixtures can be used, and an anode is hung using a material in which the metal to be anodized is formed as an operating electrode in an oxidation treatment tank containing the electrolyte. Next, a platinum (Pt) or carbon (carbon) electrode as a counter (counter) electrode may be formed by oxidizing the cathode. Preferably, the electrolytic solution may be formed at a temperature of -5 to 10°C using 0.1-0.5M oxalic acid as an electrolytic solution, more preferably 0.2-0.4M oxalic acid electrolytic solution and at a temperature of -2 to 2°C. have.

In the method for treating the surface of an aluminum alloy outer plate or component for a heat exchanger according to the present invention with hydrophobicity, the aluminum alloy for the outer plate or component of the heat exchanger in step 1 may be a 5000 series aluminum alloy such as Al-Mg system, and 5000 series aluminum alloys are Al 5005, Al 5023, Al 5042, Al 5052, Al 5054, Al 5056, Al 5082, Al 5083, Al 5084, Al 5086, Al 5154, Al 5182, Al 5252, Al 5352, Al 5383, It may be one or more selected from the group consisting of Al 5454, Al 5456, Al 5457, Al 5657 and Al 5754.

In the method of hydrophobically treating the surface of an aluminum alloy outer plate or component for a heat exchanger according to the present invention, the heat exchanger is a group consisting of an evaporator, a condenser, a radiator, an oil cooler, a fuel cell, a heater core, a waste heat recovery device, piping, and a condenser It may be one or more selected from, but is not limited thereto.

Aluminum alloy shell or parts for heat exchangers with hydrophobic surfaces

In addition, the present invention provides an aluminum alloy outer plate or component for a heat exchanger having a hydrophobic surface produced by a method of treating the surface of the aluminum alloy outer plate or component for heat exchange with hydrophobicity.

The aluminum alloy according to the present invention may be a three-dimensional shape of anodized aluminum oxide (anodic aluminum oxide) layer is formed on the surface.

The heat exchanger may be one or more selected from the group consisting of an evaporator, a condenser, a radiator, an oil cooler, a fuel cell, a heater core, a waste heat recovery device, piping, and a condenser, but is not limited thereto.

A method of forming an anodized film having a pillar-on-pore structure on the surface of an aluminum alloy outer plate or component for a heat exchanger

In addition, the present invention is pre-patterning to remove the primary anodized film by etching after first anodizing an aluminum alloy for a heat exchanger outer plate or component at 30-50 V for 5-15 hours. ) Step (step 1);

A second anodizing treatment of the aluminum alloy pre-patterned in step 1 (step 2);

In step 2, the second anodized aluminum alloy is immersed in a solution of 0.01-10M phosphoric acid (H ₃ PO ₄ ) for 45-65 minutes to pore widening (step 3); And

In the step 3, the third step of anodizing the aluminum alloy having the pore expansion completed (step 4); includes,

The second anodization of step 2 and the third anodization of step 4 are characterized by anodizing using hard anodizing conditions that anodize at 70-90V for 20-40 seconds, respectively. ,

Provided is a method of forming an anodized film having a pillar-on-pore structure on the surface of an aluminum alloy outer plate or component for a heat exchanger.

In the method of forming an anodized film having a pillar-on-pore structure on the surface of an aluminum alloy outer plate or component for a heat exchanger according to the present invention, the secondary anodization of step 2 and the step 4 The third anodization of the anodized using hard anodizing conditions for anodizing at 75-85V for 25-35 seconds, respectively, and the pore expansion in step 3 is the secondary anodization in step 2 The treated aluminum alloy may be immersed in a 0.05-1.0M phosphoric acid (H ₃ PO ₄ ) solution for 55-65 minutes, preferably, secondary anodization in step 2 and tertiary anode in step 4 The oxidation is anodized using hard anodizing conditions, which anodize at 78-82V for 28-32 seconds, respectively, and the pore expansion in step 3 is aluminum subjected to the secondary anodization in step 2 The alloy may be immersed in a 0.05-0.5M phosphoric acid (H ₃ PO ₄ ) solution for 58-62 minutes.

In the method of forming an anodized film having a pillar-on-pore structure on the surface of an aluminum alloy outer plate or component for a heat exchanger according to the present invention, the secondary anodized aluminum by the secondary anodization A layer is formed, and a tertiary anodized aluminum layer may be formed by the tertiary anodization. At this time, the secondary anodized aluminum layer region by secondary anodization is formed on the outer side away from the aluminum alloy surface, and the tertiary anodized aluminum layer region by tertiary anodization is formed on the inner side closer to the aluminum alloy surface. It can be.

In the method for forming an anodized film having a pillar-on-pore structure on the surface of an aluminum alloy outer plate or component for a heat exchanger according to the present invention, the pillar-on-pore (pillar) on the aluminum alloy surface An anodized aluminum oxide layer having a -on-pore structure may be formed, thereby exhibiting excellent hydrophobicity.

In the method of forming an anodized film having a pillar-on-pore structure on the surface of an aluminum alloy outer plate or a component for a heat exchanger according to the present invention, the primary anodization in step 1, the second step The electrolytes that undergo secondary anodization and tertiary anodization in step 3 are sulfuric acid (H ₂ SO ₄ ), phosphoric acid (H ₃ PO ₄ ), and oxalic acid (C ₂ H2O ₄ ), respectively. Any one of chromic acid, hydrofluoric acid, and dipotassium phosphate (K ₂ HPO ₄ ) may be used, or any one of these mixtures may be used, and the anode may be used in the oxidation treatment tank containing the electrolyte solution It may be made by oxidizing the anode by using a material on which a metal to be oxidized is formed as a working electrode, and then a cathode by using a platinum (Pt) or carbon electrode as a counter electrode. Preferably, the electrolytic solution may be formed at a temperature of -5 to 10°C using 0.1-0.5M oxalic acid as an electrolytic solution, more preferably 0.2-0.4M oxalic acid electrolytic solution and at a temperature of -2 to 2°C. have.

In the method of forming an anodized film having a pillar-on-pore structure on the surface of an aluminum alloy outer plate or component for a heat exchanger according to the present invention, the aluminum alloy for the outer plate or component of the heat exchanger in step 1 It may be a 5000 series aluminum alloy, such as silver Al-Mg system, the 5000 series aluminum alloy is Al 5005, Al 5023, Al 5042, Al 5052, Al 5054, Al 5056, Al 5082, Al 5083, Al 5084, Al 5086 , Al 5154, Al 5182, Al 5252, Al 5352, Al 5383, Al 5454, Al 5456, Al 5457, Al 5657 and Al 5754.

In the method of forming an anodized film having a pillar-on-pore structure on the surface of an aluminum alloy outer plate or component for a heat exchanger according to the present invention, the heat exchanger is an evaporator, a condenser, a radiator, an oil cooler, It may be one or more selected from the group consisting of a fuel cell, a heater core, a waste heat recovery device, piping, and a condenser, but is not limited thereto.

A method of forming an anodized film having a pillar-on-pore structure on the surface of an aluminum alloy outer plate or component for a heat exchanger of the present invention is a low cost of an anodized film in the POP form on the surface of an aluminum alloy housing. It has the economic effect of being able to manufacture in a short time.

Aluminum alloy shell or component for heat exchangers with a hydrophobic surface with a pillar-on-pore structure

In addition, the present invention is a pillar-on-pore prepared by a method of forming an anodized film having a pillar-on-pore structure on the surface of the aluminum alloy shell or component for the heat exchanger. Provided is an aluminum alloy outer plate or component for a heat exchanger having a hydrophobic surface having a pore structure.

The heat exchanger may be one or more selected from the group consisting of an evaporator, a condenser, a radiator, an oil cooler, a fuel cell, a heater core, a waste heat recovery device, piping, and a condenser, but is not limited thereto.

In the present invention, the wettability to water of the aluminum alloy on which the anodized film having the super-hydrophobic surface of the pillar-on-pore structure according to the present invention is formed is very low, and superhydrophobicity (super-hydrophobicity) is excellent. It was confirmed (see Experimental Example 2).

Hereinafter, the present invention will be described in more detail by the following examples. However, the following examples are merely illustrative of the present invention, and the contents of the present invention are not limited by the following examples.

< Example > Aluminum alloy anodized film production

To prepare an aluminum alloy anodized film, pre-patterning, pore widening (PW), and voltage modulation were performed using an aluminum 5052 alloy. The component information of the aluminum 5052 alloy (Al 5052, size 20×30 mm) is as follows; Mg 2.2~2.8%, Si 0.25%, Fe 0.40%, Cu 0.10%, Mn 0.10%, Zn 1.0%, Cr 0.15~0.35% and Al Balance.

Step 1: Pre-patterning process through primary anodization and chemical etching

As a 5000 series aluminum (Al) alloy plate for the production of anodized film, an aluminum 5052 alloy (Alcoa INC, USA) was used for ultrasonic treatment in acetone and ethanol for 10 minutes to remove impurities on the surface of the aluminum 5052 alloy. Was washed. In order to obtain the surface roughness, the ultrasonically cleaned aluminum 5052 alloy was added to a mixed solution of ethanol and perchloric acid (Junsei, C ₂ H ₅ OH:HClO ₄ = 4:1 (v/v)), and a voltage of 20 V at room temperature (20° C.) And electrolytic polishing for 1 minute. It was confirmed that the surface of the aluminum alloy on which the electropolishing was completed was highly reflective and the surface was flat.

The electro-polished aluminum 5052 alloy (thickness 1 mm, size 20×30 mm) was used as a working electrode, and a platinum (Pt) electrode was used as the cathode, and the two electrodes were kept at a distance between poles at a interval of 5 cm to 1 Primary anodization was performed. The primary anodization was carried out while 0.3M oxalic acid was used as the electrolyte, and the temperature of the electrolyte was kept constant at 0°C using a double beaker. The alumina layer was grown by performing a primary anodization process for 6 hours by applying a voltage of 40V using a constant voltage method to stir at a constant rate to suppress the disturbance of stable oxide growth due to local temperature rise.

The alumina layer grown through the primary anodization treatment is immersed for 10 hours in a solution of chromic acid (1.8 wt%) and phosphoric acid (6 wt%) at 65° C. for 10 hours to remove the grown alumina layer. The pre-patterning process was performed.

Step 2-4: Second and third anodization and pore expansion processes

Specifically, in order to obtain a desired coating structure on the surface of the aluminum 5052 alloy, after the pre-pattering was completed, secondary anodization, pore expansion, and tertiary anodization were performed.

Specifically, the secondary and tertiary anodization processes of the Examples were performed under the same acid electrolyte conditions as the primary anodization process of step 1 above, and soft anodization (MA) or 80V using a relatively low voltage of 40V. Using two techniques of hard anodization (HA) using a high voltage of, anodization was performed by selectively adjusting the magnitude and order of the voltage applied during the second and third anodization. At this time, the soft anodization was performed at 40V for 30 minutes, and the hard anodization was performed at 80V for 30 seconds. On the other hand, the secondary and tertiary anodization processes of the comparative example were anodized using super hard anodization (SA) conditions of voltage and time as shown in Table 1 below.

In addition, the alumina layer grown through the secondary anodization is subjected to a pore widening (PW) process that is immersed in a 0.1 M phosphoric acid solution at 30° C. for 30 to 60 minutes before performing the tertiary anodization, The third anodization was performed to grow an aluminum anodized film.

Second anodization (step 2), pore expansion (step 3) and tertiary anodization (step 4) processes were carried out under the conditions shown in Table 1, and the structure shapes of aluminum 5052 alloy surfaces were controlled in Examples 1 to An aluminum alloy anodized film of 4 was obtained.

Pre-patterning
(Step 1) Process mode
(Step 2-4) Second anodization
(Step 2) Pore Expansion (Phase 3) Tertiary anodization
(Step 4) Voltage (V) Time(min) Time(min) Voltage (V) Time(min) Example 1 Perform MA→PW→MA 40 30 30 40 30 Example 2 Perform MA→PW→HA 40 30 30 80 0.5 Example 3 Perform HA→PW→MA 80 0.5 30 40 30 Example 4 Perform HA→PW→HA 80 0.5 30 80 0.5 Example 5 Perform MA→PW→MA 40 30 40 40 30 Example 6 Perform MA→PW→HA 40 30 40 80 0.5 Example 7 Perform HA→PW→MA 80 0.5 40 40 30 Example 8 Perform HA→PW→HA 80 0.5 40 80 0.5 Example 9 Perform MA→PW→MA 40 30 50 40 30 Example 10 Perform MA→PW→HA 40 30 50 80 0.5 Example 11 Perform HA→PW→MA 80 0.5 50 40 30 Example 12 Perform HA→PW→HA 80 0.5 50 80 0.5 Example 13 Perform MA→PW→MA 40 30 60 40 30 Example 14 Perform MA→PW→HA 40 30 60 80 0.5 Example 15 Perform HA→PW→MA 80 0.5 60 40 30 Example 16 Perform HA→PW→HA 80 0.5 60 80 0.5 Comparative Example 1 Perform SA→PW→SA 100 0.5 30 100 0.5 Comparative Example 2 Perform SA→PW→SA 100 5 sec 30 100 5 sec Comparative Example 3 Perform SA→PW→SA 120 0.5 30 120 0.5 Comparative Example 4 Perform SA→PW→SA 120 4 sec 30 120 4 sec

< Experimental Example 1> Structural properties analysis of aluminum alloy anodized film according to secondary and tertiary anodization conditions (voltage and time) and pore expansion time

As shown in Table 1, Examples 1 to 16 prepared by performing various modes and performing different pore expansion times of MA→PW→MA, MA→PW→HA, HA→PW→HA and HA→PW→MA The surface and cross-sectional shape of the porous aluminum alloy anodized film was observed using a field emission scanning electron microscope (FE-SEM) system (AURIGA® small dual-bean FIB-SEM, Zeiss).

Each aluminum alloy anodized film specimen was cut into small pieces, fixed on a stage with carbon tape, coated with gold (Au) for 15 seconds by sputtering, and then imaged with a scanning electron microscope (SEM). At this time, the film specimen was bent at 90° to generate parallel cracks, and the surface and cross-sectional structures of the aluminum alloy anodized film were observed and are shown in FIGS. 1 to 4.

1 to 4 are top views and cross sections of an aluminum alloy anodized film formed on the pre-patterned aluminum alloy surfaces of Examples 1 to 4, 5 to 8, 9 to 12, and 13 to 16, respectively, according to the present invention. This is a scanning electron microscope (SEM) image of a three-dimensional structure of (cross view); At this time, MA was performed for 30 minutes at 40V, HA for 30 seconds at 80V, and PW for 30-60 minutes at 30°C, and the scale bars of the surface and cross-sections were 200 nm and 1 μm, respectively.

As shown in Figures 1 to 4, in most cases, the results of the pore diameter increase in the secondary anodization region of the aluminum alloy anodized film by the PW process, but the structure of the tertiary anodization region It did not affect. Therefore, in Examples 1 to 16, since the pore sizes of the secondary anodization region and the tertiary anodization region are different, the criteria for the secondary and tertiary anodization regions can be divided into pore size transitions.

In addition, it was found that the anodized film containing HA of the type of voltage had a larger pore diameter and the gap between the pore and the space than the anodized film containing MA of the voltage. From these results, it was confirmed that the magnitude of the anodization voltage can affect the size of the pores.

On the other hand, as shown in Figures 3 and 4, in the case of Examples 12 and 16 manufactured by performing PW 50 or 60 minutes in HA→PW→HA mode, the lower part in the cross-view image In the tertiary anodization region of, it was confirmed that aligned pores of the linear structure were formed, and in the secondary anodization region on the linear pores, a tip-like structure was formed. On the top view image, it was shown that a white (light gray) anode oxide was formed next to the pores shown in black, and the corresponding portion was a tip-like structure portion formed in the secondary anodization region. Confirmed.

Therefore, in Examples 12 and 16, unlike the other examples, an anodized film having a pillar-on-pore shape with a bundle-shaped pillar formed on the pore structure was prepared. In particular, it was confirmed that it exhibits a much clearer pillar-on-pore form when prepared under the conditions of Example 16.

As a result, the parameters of the secondary and tertiary anodizing voltage magnitudes directly affect the pore size, controlling not only the pore diameter and the gap between the pores and the pore space, but also the growth of a three-dimensional aluminum anodized film. It was confirmed that it can be controlled, in particular, HA (80V, 30sec)→PW(60min)→HA(80V, 30sec) of Example 16 is a condition that can produce an anodized film having the clearest POP structure. Confirmed.

< Experimental Example 2> Analysis of water repellent properties of anodized aluminum alloy films according to secondary and tertiary anodization conditions (voltage and time) and pore expansion time

In order to confirm the effect of the structure shape of the aluminum alloy anodized film on the water repellent properties, each of the porous aluminum alloy anodized films of Examples 1 to 16 was 1H, 1H, 2H, a coating material having a low surface energy for 24 hours in a vacuum chamber. , Self-Assembled Monolayer (SAM) coating with 2Hperfluorodecyltrichlorosilane (FDTS) to implement a hydrophobic surface, and then wettability to water was evaluated.

In order to evaluate the wettability of the surface of the porous aluminum alloy anodized film structures of Examples 1 to 4 coated with FDTS, a contact angle measurement method was used to analyze the contact angle of 3 μl of deionized water droplets at room temperature. In addition, the FDTS coated on the surface of the aluminum alloy without anodization was used as a control to measure the contact angle in the same manner. For each specimen, the average value was calculated by measuring the contact angle at different locations at least 5 times, and the results are shown in Table 2 and FIGS. 5 to 8 below.

5 to 8 are contact angles for water droplets after FDTS coating on aluminum alloy anodized films formed on the pre-patterned aluminum alloy surfaces of Examples 1 to 4, 5 to 8, 9 to 12, and 13 to 16, respectively, according to the present invention. It is an image showing the results of measuring; (a) Control (control), (b) MA→PW→MA, (c) MA→PW→HA, (d) HA→PW→MA and (e) HA→PW→HA.

Process mode
(Step 2-4) Contact angle(°) Control - 114.8±0.31 Example 1 MA→PW(30min)→MA 136.6±0.58 Example 2 MA→PW(30min)→HA 139.8±0.24 Example 3 HA→PW(30min)→MA 149.2±1.35 Example 4 HA→PW(30min)→HA 150.7±0.58 Example 5 MA→PW(40min)→MA 162.8±1.45 Example 6 MA→PW(40min)→HA 162.0±2.04 Example 7 HA→PW(40min)→MA 149.2±0.78 Example 8 HA→PW(40min)→HA 148.5±0.79 Example 9 MA→PW(50min)→MA 140.7±0.57 Example 10 MA→PW(50min)→HA 142.1±0.55 Example 11 HA→PW(50min)→MA 161.7±0.56 Example 12 HA→PW(50min)→HA 164.4±1.45 Example 13 MA→PW(60min)→MA 122.7±0.88 Example 14 MA→PW(60min)→HA 126.1±0.27 Example 15 HA→PW(60min)→MA 152.0±4.20 Example 16 HA→PW(60min)→HA 170.4±0.05 Comparative Example 1 SA→PW(30min)→SA
(SA: 80V, 30sec) 139.9±0.31 Comparative Example 2 SA→PW(30min)→SA
(SA: 100V, 5sec) 135.2±0.35 Comparative Example 3 SA→PW(30min)→SA
(SA: 120V, 30sec) 132.6±1.35 Comparative Example 4 SA→PW(30min)→SA
(SA: 120V, 4sec) 130.4±0.24

As shown in Table 2 and FIGS. 5 to 8, the porous aluminum alloy anodized films of Examples 1 to 16 prepared through MA and HA mode control and pore expansion process in the secondary and tertiary anodization processes were low. When FDTS, a material having surface energy, was coated, it was confirmed that the wettability with respect to water was lower than when FDTS was coated on an aluminum alloy base material without anodization.

On the other hand, in the case of the porous aluminum alloy anodized films of Comparative Examples 1 to 4 prepared by performing secondary and tertiary anodization at a higher voltage, the wettability was lower than that without anodization, but the present invention Except for some of the examples, it was found that the porous aluminum alloys of Examples 1 to 16 according to the present invention were generally higher than the anodized films.

In addition, the surfaces coated with FTDS on the porous aluminum alloy anodized films of Examples 4, 11, 12, 13, 15, and 16 were found to have a contact angle of 150° or higher, indicating that the wettability to water was low compared to other Comparative Examples and Examples. It was confirmed that it shows excellent superhydrophobicity (superhydrophobicity) in Examples 12 and 16. Particularly, the surface coated with FTDS on the porous aluminum alloy anodized film of Example 16 prepared in the order of HA→PW(60min)→HA exhibited the best superhydrophobicity, and showed a contact angle of 170° or more, resulting in ultra superhydrophobicity (ultra super hydrophobic).

These results indicate that control of pore diameter and pore-space spacing through control of HA (80V) mode and MA (40V) mode in the secondary and tertiary anodization processes affects the wettability of water. And the secondary and tertiary anodizing conditions (HA) used to prepare the porous aluminum alloy anodized film of Example 16 having the pillar-on-pore structure of the present invention are the optimal conditions for realizing superhydrophobicity. Did.

So far, the present invention has been focused on the preferred embodiments. Those skilled in the art to which the present invention pertains will understand that the present invention can be implemented in a modified form without departing from the essential characteristics of the present invention. Therefore, the disclosed embodiments should be considered in terms of explanation, not limitation. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the equivalent range should be construed as being included in the present invention.

Claims (14)

Pre-patterning step of removing the primary anodized film by etching after first anodizing an aluminum alloy for a heat exchanger plate or component at 30-50 V for 5-15 hours (step 1) );
A second anodizing treatment of the aluminum alloy pre-patterned in step 1 (step 2);
Pore widening the second anodized aluminum alloy in step 2 (step 3); And
In the step 3, the third step of anodizing the aluminum alloy having the pore expansion completed (step 4); includes,
The secondary anodization in step 2 and the tertiary anodization in step 4 are respectively mild anodizing conditions for anodizing at 20-50V for 10-50 minutes; And hard anodizing conditions for anodizing at 60-90 V for 10-50 seconds; Characterized in that the anodizing treatment using any one of the conditions,
A method of treating the surface of an aluminum alloy shell or component for heat exchangers with hydrophobicity.
According to claim 1,
The pore expansion of step 3 is characterized in that the aluminum alloy which has undergone the secondary anodizing treatment of step 2 is immersed in a solution of 0.01-10M phosphoric acid (H ₃ PO ₄ ) for 20-70 minutes, and the aluminum alloy shell for heat exchanger Or a method of treating the surface of a part with hydrophobicity.
According to claim 1,
The secondary anodization in step 2 is hard anodized at 70-90V for 20-40 seconds, and the pore expansion in step 3 is immersed in a solution of 0.01-10M phosphoric acid (H ₃ PO ₄ ) for 45-65 minutes. , The third anodization of step 4 is characterized in that the hard anodization treatment for 20-40 seconds at 70-90V, the method of hydrophobically treating the surface of the aluminum alloy shell or part for the heat exchanger.
According to claim 1,
The second anodization of step 2 is hard anodized at 70-90V for 20-40 seconds, and the pore expansion of step 3 is immersed in a solution of 0.01-5.0M phosphoric acid (H ₃ PO ₄ ) for 55-65 minutes. And, the tertiary anodization of step 4 is characterized in that the hard anodization for 20-40 seconds at 70-90V, the method of hydrophobically treating the surface of the aluminum alloy shell or part for the heat exchanger.
According to claim 1,
Control any one or more of a pore diameter and an interpore distance between pores and pore spaces of a three-dimensional shape anodized aluminum oxide layer formed on the surface of the aluminum alloy outer plate or component for the heat exchanger. A method of treating a surface of an aluminum alloy outer plate for heat exchanger or a component with hydrophobicity, characterized in that hydrophobicity is expressed thereby.
The method of claim 5,
The three-dimensionally shaped anodized aluminum layer formed on the surface of the aluminum alloy outer plate or component for the heat exchanger has a pillar-on-pore structure, How to make the surface hydrophobic.
According to claim 1,
A method of treating the surface of an aluminum alloy outer plate or component for a heat exchanger with hydrophobicity, wherein the aluminum alloy for the outer plate or component of the heat exchanger in step 1 is a 5000 series aluminum alloy.
The method of claim 7,
The 5000 series aluminum alloy is Al 5005, Al 5023, Al 5042, Al 5052, Al 5054, Al 5056, Al 5082, Al 5083, Al 5084, Al 5086, Al 5154, Al 5182, Al 5252, Al 5352, Al 5383 , Al 5454, Al 5456, Al 5457, Al 5657 and Al 5754, characterized in that at least one member selected from the group consisting of, the method of treating the surface of the aluminum alloy shell or parts for heat exchangers with hydrophobicity.
According to claim 1,
The heat exchanger is an aluminum alloy shell for a heat exchanger, characterized in that it is a heat exchanger used in at least one device selected from the group consisting of an evaporator, a condenser, a radiator, an oil cooler, a fuel cell, a heater core, a waste heat recovery device, piping, and a condenser. Or a method of treating the surface of a part with hydrophobicity.
An aluminum alloy shell or component for a heat exchanger having a hydrophobic surface produced by the method of claim 1.
The method of claim 10,
The aluminum alloy outer plate or component for the heat exchanger is characterized in that a three-dimensional shape anodized aluminum oxide layer is formed on the surface, an aluminum alloy outer plate or component for a heat exchanger having a hydrophobic surface.
Pre-patterning step of removing the primary anodized film by etching after first anodizing an aluminum alloy for a heat exchanger plate or component at 30-50 V for 5-15 hours (step 1) );
A second anodizing treatment of the aluminum alloy pre-patterned in step 1 (step 2);
In step 2, the second anodized aluminum alloy is immersed in a solution of 0.01-10M phosphoric acid (H ₃ PO ₄ ) for 45-65 minutes to pore widening (step 3); And
In the step 3, the third step of anodizing the aluminum alloy having the pore expansion completed (step 4); includes,
The second anodization of step 2 and the third anodization of step 4 are characterized by anodizing using hard anodizing conditions that anodize at 70-90V for 20-40 seconds, respectively. ,
A method of forming an anodized film having a pillar-on-pore structure on the surface of an aluminum alloy outer plate or component for a heat exchanger.
The method of claim 12,
The secondary anodization in step 2 and the tertiary anodization in step 4 are anodized using hard anodizing conditions that anodize at 75-85V for 25-35 seconds, respectively.
The pore expansion of step 3 is characterized in that the aluminum alloy that has undergone the secondary anodizing treatment of step 2 is immersed in a solution of 0.05-1.0M phosphoric acid (H ₃ PO ₄ ) for 55-65 minutes, aluminum alloy for heat exchanger A method of forming an anodized film having a pillar-on-pore structure on the surface of an outer plate or a component.
An aluminum alloy shell or component for a heat exchanger having a hydrophobic surface of a pillar-on-pore structure produced by the method of claim 12.

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