KR102179028B1 - Method for superhydrophobic surface of the outer panel or component for heat exchanger - Google Patents

Abstract

The present invention relates to a method of superhydrophobicizing the surface of an aluminum alloy shell or component for a heat exchanger, and the method of treating the surface of an aluminum alloy shell or component for a heat exchanger to be hydrophobic is formed on the surface of an aluminum alloy through anodization voltage and time control. By implementing the pore shape, diameter, and density of the anodized aluminum layer in various forms such as pillar-on-pores, it is economical to manufacture an aluminum alloy with a controlled three-dimensional anodized film structure at low cost in a short time. The aluminum alloy having a controlled anodized film structure manufactured by the above method has excellent superhydrophobicity, corrosion resistance, and thermal conductivity, and thus can be used as a heat exchanger outer plate or a component.

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 a heat exchanger shell plate or component, and more specifically, to a method of hydrophobically treating the surface of an aluminum alloy shell plate or component for a heat exchanger.

The aluminum oxide film with nano-sized pores arranged in a regular hexagonal structure was first studied and reported in 1995, and has been used in nanotechnology such as carbon nanotubes and nanowires using an aluminum anodizing process with an expanded range of applications. In addition, various nanotechnology researches are actively underway.

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

The electrochemical anodizing process has been used for surface treatment of metallic materials for over 70 years. Nanostructures fabricated through the anodization process can implement nanostructures with less budget and time than expensive electronic lithography or semiconductor etching processes using silicon. However, in the case of this anodized film, it has a two-dimensional porous arrangement that can control only the side dimensions.

In addition, in the production of regularly arranged anodized aluminum films by controlling the type and concentration of the acid electrolyte of aluminum alloy, many studies and technologies such as the aquatic acid method, the sulfuric acid method, and the phosphoric acid method have been developed, but the type and concentration of the acid electrolyte change. The anodic oxidation process is limited in the increase of the pore diameter and the gap between the pores and the pores, and this technique is also possible only to produce a two-dimensional porous anodized film.

The pillar-on-pore (POP) structure, which is a structure in which a sharp pillar on top of the pore is formed in a single or bundle shape, has a higher contact angle than the conventional planar hexagonal porous surface. contact angle) and low contact angle hysteresis, and thus has excellent superhydrophobic properties. In addition, the pillar-on-pore structure has properties such as hydrodynamic drag reduction, anticorrosion, anti-biofouling, and anti-icing, so it can realize the surface of smartphones and home appliances. It can play a big role. However, a technique for forming such a pillar-on-pore structure on a semiconductor or high-purity aluminum substrate has been studied, but it is very difficult to form it on an alloy, and has not been studied yet. In general, a lot of research has been done on the technology for manufacturing a structure having a three-dimensional porous arrangement from an aluminum substrate of high purity, but in the actual industry, it is used in an alloy form rather than a high purity aluminum substrate, and it is intended for high purity aluminum substrates. When the researched technology is applied to an aluminum alloy used for actual commercialization, there is a problem that it is difficult to reproduce the same formation control.

On the other hand, a heat exchanger is a device that exchanges heat between two fluids with different temperatures and humidity, and consists of a stacked structure of heat exchange elements and allows two fluids with different temperatures and humidity to pass alternately so as to prevent sensible heat exchange and moisture exchange due to temperature difference. It is structured to perform latent heat exchange. In this case, heat exchange is performed by conduction in the heat exchange element and convection between fluids adjacent to the heat exchange element. Until recently, copper heat exchangers using copper as heat exchange elements occupied most of the heat exchanger market due to excellent thermal 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 (household electronics: air conditioners, refrigerators, outdoor units, dehumidifiers). .

When an aluminum heat exchanger is used for cooling, moisture contained in the air is condensed on the surface of the heat exchanger to form small water droplets, and these water droplets increase the air resistance of the heat exchanger and decrease 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 surface of the heat exchanger. Accordingly, in addition to a treatment method to increase corrosion resistance, development of a material having improved superhydrophobicity (superwater repellency) is required.

Accordingly, the present applicant solved the conventional problems as described above, and a method of manufacturing an aluminum alloy film for a heat exchanger shell or parts having a three-dimensional porous arrangement, and a method of forming a pillar-on-pore structure on the alloy. For development, by controlling the anodic oxidation voltage on the pre-patterned aluminum alloy and performing the secondary and tertiary anodization processes, a three-dimensional porous film having various structures such as pillar-on-pores is produced. Thus, the present invention was completed.

Korean Patent Registration No. 10-0935964

It is an object of the present invention to provide a method for hydrophobically treating the surface of an aluminum alloy shell or component for a heat exchanger.

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

Another object of the present invention is to provide a method of forming an anodized film having a pillar-on-pore structure on the surface of an aluminum alloy shell 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 manufactured by the above method.

To achieve the above object,

The present invention is a pre-patterning step of first anodizing an aluminum alloy for a heat exchanger outer plate or parts at 30-50V for 5-15 hours, and then etching to remove the first anodized film. (Step 1); Secondary anodizing the aluminum alloy for which pre-patterning has been completed in step 1 (step 2); Pore widening the aluminum alloy subjected to the secondary anodization treatment in step 2 (step 3); And performing a third anodization treatment on the aluminum alloy having pore expansion completed in step 3 (step 4), wherein the second anodization of step 2 and the third anodization of step 4 are 20-50V, respectively. Mild anodizing conditions for anodizing for 10-50 minutes at And hard anodizing conditions for anodizing at 60-90V for 10-50 seconds. It provides a method of hydrophobically treating the surface of an aluminum alloy shell or component for a heat exchanger, characterized in that the anodization treatment is performed using any one of conditions.

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

Further, the present invention is pre-patterning in which an aluminum alloy for a heat exchanger shell or parts is first anodized at 30-50V for 5-15 hours, and then etched to remove the first anodized film. ) Step (step 1); Secondary anodizing the aluminum alloy for which pre-patterning has been completed in step 1 (step 2); Immersing the aluminum alloy subjected to the secondary anodization treatment in step 2 in a 0.01-10M phosphoric acid (H ₃ PO ₄ ) solution for 55-65 minutes to expand pores (step 3); And performing a third anodization treatment on the aluminum alloy having pore expansion completed in step 3 (step 4), wherein the secondary anodization of step 2 and the third anodization of step 4 are respectively 70-90V A pillar-on-pore on the surface of an aluminum alloy shell or component for a heat exchanger, characterized in that anodizing is performed using hard anodizing conditions for anodizing at 20-40 seconds. ) It provides a method of forming an anodized film of the structure.

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

The method of treating the surface of an aluminum alloy outer plate or part for a heat exchanger of the present invention with hydrophobicity is to determine the pore shape, diameter, and density of the anodized aluminum layer formed on the aluminum alloy surface by controlling the anodization voltage and time. By implementing in various forms such as pores, an aluminum alloy having a controlled anodization film structure of a three-dimensional shape can be produced in a short time at low cost, and has an economic effect, and an aluminum alloy having a controlled anodization film structure manufactured by the above method Since silver is excellent in superhydrophobicity, corrosion resistance and thermal conductivity, it can be used as a heat exchanger outer plate or part.

1 is a scanning electron microscope photographing a three-dimensional structure of an aluminum alloy anodized film formed on the prepatterned aluminum alloy surface of Examples 1 to 4 according to the present invention (top view) and cross-section ( SEM) is an image; At this time, MA was performed at 40V for 30 minutes, HA at 80V for 30 seconds, and PW at 30°C for 30 minutes, and the scale bars of the surface and cross-section were 200 nm and 1 μm, respectively.
FIG. 2 is a scanning electron microscope photographing a three-dimensional structure of an aluminum alloy anodizing film formed on the prepatterned aluminum alloy surface of Examples 5 to 8 according to the present invention (top view) and cross-section ( SEM) is an image; At this time, MA was carried out at 40V for 30 minutes, HA at 80V for 30 seconds, and PW at 30°C for 40 minutes, and the scale bars of the surface and cross section were 200 nm and 1 μm, respectively.
3 is a scanning electron microscope photographing a three-dimensional structure of an aluminum alloy anodized film formed on the prepatterned aluminum alloy surface of Examples 9 to 12 according to the present invention (top view) and cross-section ( SEM) is an image; At this time, MA was carried out at 40V for 30 minutes, HA at 80V for 30 seconds, and PW at 30°C for 50 minutes, and scale bars of the surface and cross-section were 200 nm and 1 μm, respectively.
4 is a scanning electron microscope photographing a three-dimensional structure of an aluminum alloy anodized film formed on the prepatterned aluminum alloy surface of Examples 13 to 16 according to the present invention (top view) and cross-section ( SEM) is an image; At this time, MA was performed at 40V for 30 minutes, HA at 80V for 30 seconds, and PW at 30°C for 60 minutes, and the scale bars of the surface and cross-section were 200 nm and 1 μm, respectively.
5 is an image showing a result of measuring a contact angle with respect to water droplets after FDTS coating on an aluminum alloy anodized film formed on the prepatterned aluminum alloy surface of Examples 1 to 4 according to the present invention; (a) 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).
6 is an image showing a result of measuring a contact angle with respect to water droplets after FDTS coating on the aluminum alloy anodized film formed on the prepatterned aluminum alloy surface of Examples 5 to 8 according to the present invention; (a) 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 a result of measuring a contact angle with respect to water droplets after FDTS coating on an aluminum alloy anodized film formed on the prepatterned aluminum alloy surface of Examples 9 to 12 according to the present invention; (a) 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 a result of measuring a contact angle with respect to a water droplet after FDTS coating on an aluminum alloy anodized film formed on the prepatterned aluminum alloy surface of Examples 13 to 16 according to the present invention; (a) 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.

How to hydrophobically treat the surface of aluminum alloy shells or parts for heat exchangers

The present invention is a pre-patterning step of first anodizing an aluminum alloy for a heat exchanger outer plate or parts at 30-50V for 5-15 hours, and then etching to remove the first anodized film. (Step 1);

Secondary anodizing the aluminum alloy for which pre-patterning has been completed in step 1 (step 2);

Pore widening the aluminum alloy subjected to the secondary anodization treatment in step 2 (step 3); And

Including; third anodizing the aluminum alloy for which pore expansion is completed in step 3 (step 4),

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

It provides a method of hydrophobically treating the surface of an aluminum alloy shell or part for a heat exchanger.

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

In the method of hydrophobicly treating the surface of an aluminum alloy outer plate or part for a heat exchanger according to the present invention, the pore expansion of step 3 is performed by using 0.01-10M phosphoric acid (H _{3) of the} aluminum alloy subjected to the secondary anodization of step 2 PO ₄ ) It 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 immersed in a 0.05-0.5M phosphoric acid solution for 55-65 minutes, and even more preferably 0.08- It may be immersion in a 0.2M phosphoric acid solution for 58-62 minutes.

In the method of hydrophobically treating the surface of an aluminum alloy outer plate or part for a heat exchanger according to the present invention, a secondary anodized aluminum layer is formed by the secondary anodization, and the third anodization is performed by the third anodization. An aluminum layer may be formed. At this time, the area of the secondary anodized aluminum layer by secondary anodization is formed on the outside far from the surface of the aluminum alloy, and the area of the third anodized aluminum layer by the third anodization is formed on the inside close to the surface of the aluminum alloy. It can be.

According to an embodiment of the present invention, the secondary anodization of step 2 is hard anodizing at 70-90V for 20-40 seconds, and the pore expansion of step 3 is 0.01-10M phosphoric acid (H ₃ PO ₄ ) It is immersed in the solution for 45-65 minutes, and the third anodization of step 4 may be hard anodization treatment at 70-90V for 20-40 seconds, and preferably, the second anodization of step 2 is Hard anodizing treatment at 70-90V for 20-40 seconds, the pore expansion of step 3 was immersed in a 0.01-5.0M phosphoric acid (H ₃ PO ₄ ) solution for 55-65 minutes, and the third anode of step 4 Oxidation may be hard anodization treatment at 70-90V for 20-40 seconds, more preferably the secondary anodization of step 2 is hard anodization treatment at 75-85V for 25-35 seconds, and the step The pore expansion of 3 is immersed in a 0.05-1.0M phosphoric acid (H ₃ PO ₄ ) solution for 55-65 minutes, and the third anodization of step 4 is to perform hard anodization at 75-85V for 25-35 seconds. And, more preferably, the secondary anodization of step 2 is hard anodizing at 78-82V for 28-32 seconds, and the pore expansion of step 3 is 0.05-0.5M phosphoric acid (H ₃ PO ₄ ) It is immersed in the solution for 28-32 minutes, and the third anodization of step 4 may be 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 part for a heat exchanger according to the present invention, the pore diameter of a three-dimensional anodic aluminum oxide layer formed on the surface of the aluminum alloy, and Hydrophobicity may be expressed by controlling at least one of pores and interpore distances.

In the method of hydrophobically treating the surface of an aluminum alloy shell or component for a heat exchanger according to the present invention, the three-dimensional anodized aluminum layer formed on the surface of the aluminum alloy shell or component for a heat exchanger is pillar-on-pores ( pillar-on-pore) structure.

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

In the method of hydrophobically treating the surface of an aluminum alloy shell or component for a heat exchanger according to the present invention, the electrolyte in which the first anodization in step 1, the secondary anodization in step 2, and the third anodization in step 3 is performed is Sulfuric acid (H ₂ SO ₄ ), phosphoric acid (H ₃ PO ₄ ), oxalic acid (C ₂ H2O ₄ ), chromic acid, hydrofluoric acid, potassium hydrogen phosphate ( Any one of dipotassium phosphate, K ₂ HPO ₄ ) or a mixture thereof can be used, and a material on which the metal to be anodized is formed in the oxidation treatment tank containing the electrolyte is used as a working electrode to attach an anode. Next, a platinum (Pt) or carbon (carbon) electrode may be used as a counter electrode, and a cathode may be hung and oxidized. Preferably, the electrolyte solution may be made at a temperature of -5 to 10°C using 0.1-0.5M oxalic acid as an electrolyte solution, more preferably 0.2-0.4M oxalic acid electrolyte and at a temperature of -2 to 2°C. have.

In the method for treating the surface of an aluminum alloy shell or component for a heat exchanger according to the present invention with hydrophobicity, the heat exchanger shell or component aluminum alloy of step 1 may be a 5000 series aluminum alloy such as Al-Mg, and the like, 5000 series aluminum alloys include 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 hydrophobic treatment of the surface of an aluminum alloy shell 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, a pipe and a condenser. It may be one or more selected from, but is not limited thereto.

Aluminum alloy shells or parts for heat exchangers with hydrophobic surfaces

In addition, the present invention provides an aluminum alloy shell or component for a heat exchanger having a hydrophobic surface manufactured by hydrophobically treating the surface of the aluminum alloy shell or component for the heat exchanger.

The aluminum alloy according to the present invention may have a three-dimensional anodic aluminum oxide layer formed on its 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, a pipe, and a condenser, but is not limited thereto.

Method of forming an anodized film of pillar-on-pore structure on the surface of aluminum alloy outer plate or parts for heat exchanger

In addition, the present invention is pre-patterning in which an aluminum alloy for a heat exchanger shell or parts is first anodized at 30-50V for 5-15 hours, and then etched to remove the first anodized film. ) Step (step 1);

Secondary anodizing the aluminum alloy for which pre-patterning has been completed in step 1 (step 2);

Immersing the aluminum alloy subjected to the secondary anodization treatment in step 2 in a 0.01-10M phosphoric acid (H ₃ PO ₄ ) solution for 45-65 minutes to expand pores (step 3); And

Including; third anodizing the aluminum alloy for which pore expansion is completed in step 3 (step 4),

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

It provides a method of forming an anodized film having a pillar-on-pore structure on the surface of an aluminum alloy shell 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 shell or part for a heat exchanger according to the present invention, the secondary anodization of the step 2 and the step 4 The third anodization of is anodized using a hard anodizing condition of anodizing at 75-85V for 25-35 seconds, respectively, and the pore expansion of step 3 is the secondary anodization of 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, the secondary anodization of step 2 and the tertiary anode of step 4 Oxidation is anodized using hard anodizing conditions of anodizing at 78-82V for 28-32 seconds, respectively, and the pore expansion in step 3 is aluminum that has undergone the secondary anodization treatment 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 shell or part for a heat exchanger according to the present invention, the secondary anodized aluminum by the secondary anodization A layer is formed, and a third anodized aluminum layer may be formed by the third anodization. At this time, the area of the secondary anodized aluminum layer by secondary anodization is formed on the outside far from the surface of the aluminum alloy, and the area of the third anodized aluminum layer by the third anodization is formed on the inside close to the surface of the aluminum alloy. It can be.

In the method for forming an anodized film having a pillar-on-pore structure on the surface of an aluminum alloy shell or component for a heat exchanger according to the present invention, a pillar-on-pore (pillar) on the surface of the aluminum alloy Excellent hydrophobicity may be expressed by forming an anodic aluminum oxide layer having a -on-pore) structure.

In the method for forming an anodized film having a pillar-on-pore structure on the surface of an aluminum alloy shell or part for a heat exchanger according to the present invention, the first anodization of step 1, the step 2 The electrolytes in which the secondary anodic oxidation and the third anodic oxidation of step 3 are performed are sulfuric acid (H ₂ SO ₄ ), phosphoric acid (H ₃ PO ₄ ), oxalic acid (C ₂ H2O ₄ ), Any one of chromic acid, hydrofluoric acid, and potassium hydrogen phosphate (K ₂ HPO ₄ ) may be used, or any one of a mixture thereof may be used, and the anode in the oxidation treatment reactor containing the electrolyte solution It may be oxidized by attaching an anode using a material on which the metal to be oxidized is formed as a working electrode, and then attaching a cathode using a platinum (Pt) or carbon electrode as a counter electrode. Preferably, the electrolyte solution may be made at a temperature of -5 to 10°C using 0.1-0.5M oxalic acid as an electrolyte solution, more preferably 0.2-0.4M oxalic acid electrolyte 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 part for a heat exchanger according to the present invention, the heat exchanger outer plate or aluminum alloy for a part of step 1 Silver may be a 5000 series aluminum alloy such as Al-Mg, and 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 may be one or more selected from the group consisting of.

In the method of forming an anodized film having a pillar-on-pore structure on the surface of an aluminum alloy shell or component for a heat exchanger according to the present invention, the heat exchanger comprises 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, a pipe, and a condenser, but is not limited thereto.

The method of forming an anodized film of a pillar-on-pore structure on the surface of an aluminum alloy outer plate or part for a heat exchanger of the present invention is a method of forming a POP-type anodized film on the surface of an aluminum alloy housing at low cost. It has an economic effect that can be manufactured in a short time.

Aluminum alloy shells or parts for heat exchangers with a pillar-on-pore hydrophobic surface

In addition, the present invention is a pillar-on-pore (pillar-on-pore) manufactured by a method of forming an anodized film having a pillar-on-pore structure on the surface of the aluminum alloy outer plate or component for the heat exchanger. Provides aluminum alloy shells or parts for heat exchangers having a hydrophobic surface of 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, a pipe, and a condenser, but is not limited thereto.

In the present invention, the aluminum alloy with an anodized film having a superhydrophobic surface of the pillar-on-pore structure according to the present invention has very low wettability to water and excellent superhydrophobicity (superhydrophobicity) 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 anodization film manufacturing

To prepare an aluminum alloy anodized film, pre-patterning, pore widening (PW) and voltage modulation were performed using an aluminum 5052 alloy. Component information of the aluminum 5052 alloy (Al 5052, size 20×30mm) 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 producing an anodized film, an aluminum 5052 alloy (Alcoa INC, USA) was used, and sonicated in acetone and ethanol for 10 minutes to remove impurities on the surface of the aluminum 5052 alloy. And washed. To obtain the surface roughness, the ultrasonically cleaned aluminum 5052 alloy was put in 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.) Was applied to electrolytic polishing for 1 minute. It was confirmed that the surface of the aluminum alloy on which electrolytic polishing was completed was well reflected and the surface was flat.

The electrolytically polished aluminum 5052 alloy (thickness 1mm, size 20×30mm) was used as a working electrode, and a platinum (Pt) electrode was used as a cathode, and the two electrodes maintained a constant distance between poles at 5cm intervals. Secondary anodization was performed. The primary anodic oxidation was performed using 0.3M oxalic acid as an electrolyte, and a double beaker was used to maintain the electrolyte temperature constant at 0°C. In order to suppress the disturbance of stable oxide growth due to local temperature increase, the mixture was stirred at a constant speed, and the alumina layer was grown by performing the first anodization process for 6 hours by applying a voltage of 40V using a constant voltage method.

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

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

Specifically, in order to obtain a desired film 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 second and third anodization processes of the embodiment were performed under the same acid electrolyte conditions as the first anodization process of step 1, 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 controlling the magnitude and sequence of voltages applied during the secondary and tertiary 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. Meanwhile, in the second and third anodization processes of the comparative example, anodization was performed 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 in which the alumina layer is immersed in a 0.1M phosphoric acid solution at 30° C. for 30 to 60 minutes before performing the third anodization, Third anodization was performed to grow an aluminum anodized film.

Examples 1 to 1 in which the secondary anodization (step 2), pore expansion (step 3), and the third anodization (step 4) processes were performed under the conditions shown in Table 1 below, and the structural shape of the surface of the aluminum 5052 alloy was controlled. An aluminum alloy anodized film of 4 was obtained.

Pre-patterning or not
(Step 1) Process mode
(Step 2-4) Secondary anodization
(Step 2) Pore Expansion (Step 3) 3rd 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 characteristics analysis of aluminum alloy anodizing film according to 2nd and 3rd anodization conditions (voltage and time) and pore expansion time

As shown in Table 1, Examples 1 to 16 prepared by performing various modes of MA→PW→MA, MA→PW→HA, HA→PW→HA and HA→PW→MA and varying the pore expansion time. 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 to observe the surface and cross-sectional structures of the aluminum alloy anodized film, as shown in FIGS. 1 to 4.

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

As shown in Figs. 1 to 4, in most cases, the result of increasing the diameter of the pores in the secondary anodization region of the aluminum alloy anodization film by the PW process was found, but the structure of the third anodization region Did not affect. Accordingly, since the sizes of pores in the secondary anodization region and the tertiary anodization region are different in all of Examples 1 to 16, the criteria for the secondary and tertiary anodization regions can be classified by the size transition of the pores.

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

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

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

As a result, the magnitude of the secondary and tertiary anodization voltage, which is a parameter, directly affects the size of the pores, controlling the pore diameter and the gap between pores and pores, as well as the growth of a three-dimensional aluminum anodized film. In particular, it was confirmed that the condition of HA (80V, 30sec) → PW (60min) → HA (80V, 30sec) of Example 16 was a condition for producing the most clear anodized layer of POP structure. Confirmed.

< Experimental example 2> Analysis of water repellency characteristics of aluminum alloy anodized film according to 2nd and 3rd anodic oxidation conditions (voltage and time) and pore expansion time

In order to confirm the influence of the structural 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 coated with 1H, 1H, 2H coating materials with low surface energy in a vacuum chamber for 24 hours , 2Hperfluorodecyltrichlorosilane (FDTS) was coated with a SAM (Self-Assembled Monolayer) to implement a hydrophobic surface, and then the wettability to water was evaluated.

To evaluate the wettability of the surface of the porous aluminum alloy anodized film structures of Examples 1 to 4 coated with FDTS, the contact angle measurement method was used to measure and analyze the contact angle of 3 µl of deionized water droplets at room temperature. In addition, the contact angle was measured by the same method using the FDTS coated on the surface of the aluminum alloy not subjected to anodization treatment as a control. The average value was calculated by measuring the contact angles at different places for each specimen at least five times, and the results are shown in Table 2 below and FIGS. 5 to 8.

5 to 8 show contact angles for water droplets after FDTS coating on the aluminum alloy anodized film formed on the prepatterned aluminum alloy surfaces of Examples 1 to 4, 5 to 8, 9 to 12 and 13 to 16 according to the present invention, respectively. It is an image showing the result of measurement; (a) 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 anodizing film of Examples 1 to 16 prepared through the MA and HA mode control and pore expansion process in the secondary and tertiary anodization process In the case of coating FDTS, which is a material having surface energy, it was confirmed that the wettability to water was lower than that of coating FDTS on an aluminum alloy base material (control) not subjected to anodization.

On the other hand, in the case of the porous aluminum alloy anodized film of Comparative Examples 1 to 4 prepared by performing the secondary and tertiary anodization at a higher voltage, the wettability was lower than that of not performing the anodization, but the present invention Except for some examples of, it was generally found to be higher than the porous aluminum alloy anodized film of Examples 1 to 16 according to the present invention.

In addition, the surface coated with FTDS on the porous aluminum alloy anodized film of Examples 4, 11, 12, 13, 15 and 16 was found to have a contact angle of 150° or more, indicating that the wettability to water was lower than that of other Comparative Examples and Examples. It was found, and among them, it was confirmed that it exhibits excellent superhydrophobicity (superhydrophobicity) in Examples 12 and 16. In particular, 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, and thus ultra-superhydrophobic (ultra). super hydrophobic) was implemented.

These results imply that the control of pore diameter and pore-to-pore spacing through HA (80V) mode and MA (40V) mode control in the 2nd and 3rd anodic oxidation process affects the wettability to water. And, it was confirmed that the secondary and tertiary anodization conditions (HA) used to prepare the porous aluminum alloy anodization film of Example 16 having a pillar-on-pore structure of the present invention are the optimal conditions for realizing superhydrophobicity. I did.

So far, the present invention has been looked at around its preferred embodiments. Those of ordinary skill in the art to which the present invention pertains will be able to 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 from an illustrative point of view rather than a limiting point of view. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the scope equivalent thereto should be construed as being included in the present invention.

Claims (14)

A pre-patterning step of removing the first anodized film by etching after first anodizing the 5000 series aluminum alloy for heat exchanger shells or parts at 30-50V for 5-15 hours ( Step 1);
Secondary anodizing the heat exchanger shell plate or the 5000 series aluminum alloy for parts, which has been pre-patterned in step 1, at 75-85V for 25-35 seconds (step 2);
The step of immersing 5000 series aluminum alloy for heat exchanger outer plate or parts subjected to secondary anodization in step 2 in a 0.05-1.0M phosphoric acid (H ₃ PO ₄ ) solution for 55-65 minutes to expand pores ( Step 3);
3rd anodizing the heat exchanger shell plate or the 5000 series aluminum alloy for parts for which pore expansion is completed in step 3 at 75-85V for 25-35 seconds (step 4); And
Including; coating the 5000 series aluminum alloy for a heat exchanger outer plate or component subjected to the third anodization in step 4 with a hydrophobic coating capable of coating a self-assembled monolayer (SAM) (step 5); including,
A method of manufacturing a superhydrophobic anodized film having a pillar-on-pore structure on the surface of a 5000 series aluminum alloy for a heat exchanger shell or parts.
The method of claim 1,
The hydrophobic coating agent capable of coating a self-assembled monolayer (SAM) in step 5 is 1H, 1H, 2H, 2H-perfluorodecyltrichlorosilane (FDTS), characterized in that, pillar-on- A method for producing a superhydrophobic anodized film having a pillar-on-pore structure.
delete delete delete delete delete The method of claim 1,
The 5000 series aluminum alloys include 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 selected from the group consisting of, a pillar-on-pore (pillar-on) on the surface of a 5000 series aluminum alloy for a heat exchanger shell plate or part -pore) structure of a superhydrophobic anodized film.
The method of claim 1,
The heat exchanger is a heat exchanger used for 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, a pipe, and a condenser. A method of manufacturing a superhydrophobic anodized film having a pillar-on-pore structure on the surface of a 5000 series aluminum alloy.
A 5000 series aluminum alloy shell plate for a heat exchanger with a superhydrophobic anodized film having a pillar-on-pore structure manufactured by the manufacturing method of claim 1.
A 5000 series aluminum alloy component for a heat exchanger having a superhydrophobic anodized film of a pillar-on-pore structure manufactured by the manufacturing method of claim 1.
A pre-patterning step of removing the first anodized film by etching after first anodizing the 5000 series aluminum alloy for heat exchanger shells or parts at 30-50V for 5-15 hours ( Step 1);
Secondary anodizing the heat exchanger shell plate or the 5000 series aluminum alloy for parts, which has been pre-patterned in step 1, at 75-85V for 25-35 seconds (step 2);
The step of immersing 5000 series aluminum alloy for heat exchanger outer plate or parts subjected to secondary anodization in step 2 in a 0.05-1.0M phosphoric acid (H ₃ PO ₄ ) solution for 55-65 minutes to expand pores ( Step 3); And
Including; the step of performing a third anodization treatment for 25-35 seconds at 75-85V for 25-35 seconds on the outer plate of the heat exchanger or the component 5000 series aluminum alloy for which pore expansion is completed in step 3 (step 4);
A method of forming an anodized film having a pillar-on-pore structure on the surface of a 5000 series aluminum alloy for a heat exchanger shell or parts.
A 5000 series aluminum alloy shell plate for a heat exchanger having an anodized film having a pillar-on-pore structure manufactured by the method of claim 12.
A 5000 series aluminum alloy component for a heat exchanger having an anodized film of a pillar-on-pore structure manufactured by the method of claim 12.

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