KR20140099690A - Magnesium anodizing method for improving corrosion resistance - Google Patents

Abstract

The present invention relates to a magnesium anodizing method comprising a pre-processing step for pre-processing a magnesium plate; a Keronite process and CNT submerging step for applying voltage of 300-700 V to Keronite electrolyte after the pre-processing step, making plasma reaction by inserting the magnesium plate into the electrolyte, forming a porous film layer having multiple pores on the surface of the magnesium plate, and permeating a hydrophilic CNT particle into the pores of the porous film layer; and a drying step for evaporating or drying moisture which remains on the surface of the magnesium plate after removing foreign substances generated in the CNT submerging step.

Description

[0001] The present invention relates to a magnesium anodizing method,

The present invention relates to a magnesium anodizing method, and more particularly, to a magnesium anodizing method which not only strengthens corrosion resistance by penetration of CNT particles into pores of a porous coating layer in a keronite process, but also realizes a dark color of dark gray color.

Pots, bowls, frying pans, cups, plates, etc., which are currently used as kitchen utensils, are manufactured in various forms using materials such as plastic, stainless steel, and aluminum alloy. In this case, kitchen appliances composed of a steel material having a large specific gravity are heavy and corrosion-resistant, and kitchen utensils made of aluminum alloy, which is resistant to corrosion and light, are widely used.

However, in the case of aluminum, when it is absorbed and accumulated in the human body, it is toxic and may have harmful effects on the human body, and development of products using new materials is urgently required.

On the other hand, magnesium is characterized by being light in weight with the lowest specific gravity among practical metals, good in elasticity, excellent in electromagnetic wave shielding property, and excellent in casting, strength, cutting workability and vibration absorbability compared with other metals.

Such magnesium is widely used in various fields such as automobile parts, portable electronic parts, mobile phones, notebook cases and the like due to its light weight and high strength properties, and there is an attempt to apply this to kitchen utensils such as frying pan and pots.

As such an attempt, a flat plate material made of a magnesium alloy is forged by a hot drawing method using a press as in Korean Patent Application No. 10-2009-0029995 (a kitchen container using a magnesium alloy plate and a manufacturing method thereof) Is described below with reference to Fig.

As shown in FIG. 1, a conventional kitchen container 100 using a magnesium plate includes a body 40 formed by forming a magnesium plate material in a container shape, a coating layer formed by coating Teflon or ceramic on the inner surface of the body, (80).

However, since magnesium itself has a very chemically reactive property, there is a disadvantage that the corrosion progresses rapidly in the air. Therefore, corrosion resistance problem is constantly emerged in a kitchen container using a conventional magnesium plate. It remains a problem.

Disclosure of the Invention The present invention has been conceived in order to solve the above-described problems, and it is an object of the present invention to provide an anodizing method capable of enhancing corrosion resistance by penetrating CNT particles into pores of a porous coating layer in a keronite process, And a method thereof.

In order to solve the above problems, the present invention provides a magnesium anodizing method comprising: a pretreatment step of pretreating a magnesium plate material; A pre-treatment step of applying a voltage of 300 to 700 V into the keronite electrolyte, placing the magnesium plate in the electrolyte to cause a plasma reaction, forming a porous coating layer on the surface of the magnesium plate to form a plurality of pores, A keronite process and a CNT immersion step in which hydrophilic CNT particles are permeated into the pores of the porous coating layer; And a drying step of removing foreign substances generated in the CNT dipping step and then evaporating or drying the moisture remaining on the surface of the magnesium plate.

It is preferable that the CNT dipping step is carried out at a temperature of room temperature of 24 to 26 DEG C and a dipping time of 15 to 30 minutes.

The pretreatment step may include: a shape processing step of processing the magnesium plate material into a shape suitable for an application product; An immersion degreasing step of retaining the surface of the magnesium plate material after the shaping step and removing organic contaminants; A chemical etching step of removing a portion of the surface of the magnesium plate having undergone the immersion degreasing step or a portion of the surface layer such as a segregation, an oxide, or a release agent existing between particles; A neutralization step of modifying an acid and a magnesium fluoride film formed on the surface of the magnesium plate after the chemical etching step is completed; And a desmutting step of removing the smut of the magnesium plate material.

Further, the method may further include a step of sealing the pores of the porous coating layer before the drying step.

In addition, the product using the magnesium plate includes a body molded into a shape suitable for the product, and a second coating layer for preventing the first coating layer and the nonstick after the body is surface-treated by the keronite process and the CNT immersion process .

The magnesium anodizing method according to the present invention not only strengthens the corrosion resistance and heat radiation property by penetrating the CNT particles into the pores of the porous coating layer in the keronite process, but also can realize an advanced color of dark gray color, thereby improving the beauty sensation.

1 is a view showing a kitchen container 100 using a conventional magnesium plate,
2 is a view showing a kitchen container 200 using a magnesium plate of the present invention,
FIG. 3 is a flowchart illustrating a manufacturing process of a product using a magnesium plate according to a preferred embodiment of the present invention.

Hereinafter, a method of manufacturing a product using a magnesium plate according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 2, the body 140 of the cooking container 200 such as a pot, a frying pan, or the like is made of a magnesium plate, and the magnesium plate is formed of a body molded by press molding or other methods 140 are subjected to a surface treatment by a keronite process and a CNT immersion process, followed by a two-step coating of a first ceramic coating layer 160 and a second ceramic non-stick coating layer (not shown). Here, the first ceramic coating layer functions to mitigate corrosion by preventing food from penetrating into the coating, and the second ceramic nonstick coating layer has a strong bonding force between the coating and the kitchen container, Strengthen the stick to keep it pressed and not stick.

Hereinafter, the keronite process and the CNT immersion process of the product using the magnesium plate according to the present invention will be described in detail, and the water washing process that can be performed after each process is omitted, and the pre-treatment process, the keronite process, and the CNT immersion process And a drying process.

The pretreatment process can be divided into a shape processing step (S100), an immersion degreasing step (S110), a chemical etching step (S120), a neutralization step (S130), and a desmutting step (S140).

First, a shape processing step (S100) of processing a magnesium plate material having a predetermined thickness into a predetermined shape is performed. At this time, the shape processing step (S100) is processed into a shape suitable for a product to be applied, for example, a frying pan, a pot, or the like.

Thereafter, an immersion degreasing step (S110) for maintaining the surface of the magnesium plate completed in the shaping step (S100) and removing the organic contaminants is implemented. At this time, the dipping and degreasing step (S110) is a step of removing the oil and organic contaminants which are generated in the shaping step (S100) or on the surface of the magnesium plate by using a degreasing liquid. The degreasing solution which can be used in the immersion degreasing step is capable of removing organic contaminants, and the composition is not particularly limited, but an alkaline aqueous solution containing a surfactant is preferably used. As the alkaline salt of the degreasing solution, a hydroxide, a phosphate, a silicate, a carbonate or the like can be applied. As the surfactant, any of a nonionic surfactant, a cationic surfactant, and an anionic surfactant may be used. Further, a chelate may be added to improve the degreasing effect. The temperature and time for applying the degreasing liquid to the magnesium plate are not particularly limited. However, it is preferable to approach the degreasing liquid within the range of 60 to 80 ° C for 5 to 15 minutes depending on the degree of contamination on the surface of the magnesium plate. The concentration of the degreasing liquid is appropriately set according to the degree of contamination on the surface of the magnesium plate, the degreasing liquid component, and the like. If the surface of the magnesium plate to be treated is excessively contaminated by the release agent or the oxide layer is grown to an extremely thick thickness, shot blasting may be performed on the surface of the magnesium plate prior to degreasing.

Table 1 below summarizes the immersion degreasing process.

Concentration of degreasing agent (ND-7) 200-300 ml / l Degreasing temperature 60 ~ 80 ℃ Degreasing time 5 to 15 minutes Liquid stirring method Air agitation ultrasonic wave 26kHz (sweep method)

When the dipping and degreasing process (S110) is completed, the washing process is repeated several times. This washing process is a process of washing organic solvents and impurities cleaned on the surface while passing through the immersion degreasing process (S110), which is a process of treating at ordinary temperature using general flowing water, Will be omitted in the following.

After the immersion degreasing process (S110) and washing process are completed, the surface of the magnesium plate is subjected to a chemical etching process (S120) and a neutralization process (S130).

The chemical etching step (S120) is a step of removing a portion mixed with a surface layer such as a segregation, an intermetallic compound, or the like present on the surface or particles of the magnesium plate. In addition, the natural oxide film and the corrosion product on the surface are removed. This chemical etching step (S120) simultaneously has the polishing action of the magnesium plate. If the ability of the etching agent is lowered, the segregation and corrosion products are not removed, and particularly the corrosion part is blackened. In such a state, the anodic oxidation coating process is not normally performed, and the adhesion of the coating film is poor. Further, if the surface of the magnesium plate after the etching treatment is roughened (overetching), the adhesion of the coating is deteriorated.

Table 2 summarizes the chemical etching process.

The concentration of the etchant (EMS) 300 to 350 g / l Solution temperature 60 to 70 ° C Liquid stirring method Air agitation Processing time 5 to 10 minutes

 When the chemical etching step (S120) is completed, the neutralization step (S130) is performed. The neutralization process (S130) is a process for improving the surface of the acid and magnesium fluoride film formed on the surface of the plate in the etching process and smoothing the desmut process. It is also necessary for the acid in the etching step not to be mixed into the desmut process solution. Table 3 summarizes the neutralization process.

Concentration of neutralizing agent (citric acid)  20 to 50 g / l Solution temperature  70 ~ 80 ℃ Processing time  10 to 25 minutes

When the neutralization step (S130) is completed, a desmutting step (S140) for removing the smut generated in the etching step is performed. At this time, the desmutting step (S140) is intended to remove the residues such as the smut remaining on the surface by the chemical etching process, that is, the corrosion product generated by etching or the alloy component remaining unetched. As the dismant liquid, an acidic or alkaline aqueous solution or the like can be used as long as it can remove the smut remaining on the surface of the magnesium plate material. The conditions such as the concentration, temperature and time of the dismant solution are appropriately adjusted according to the adhesion strength of the surface of the magnesium plate and the dismant liquid used. Table 4 summarizes the dismutting process in this way.

The concentration of disodium (NaOH) 100 to 150 g / l Solution temperature 60 to 70 ° C Liquid stirring method Air stirring method Processing time 10 to 13 minutes

After the pretreatment of the immersion degreasing step (S110), the chemical etching step (S120), the neutralization step (S130) and the desmutting step (S140) is completed, a porous coating layer is formed on the surface of the magnesium plate, A keronite process and a CNT immersion process (S150) are performed.

The keronite process (or coating) is a plasma electrolytic oxidation (CVD) coating method, in which a limited plasma discharge is induced on the surface of a magnesium substrate immersed in an electrolytic solution, The surface of the plate material is changed into a ceramic layer to obtain a ceramic thin film excellent in extreme compactness and adhesion. At this time, in the keronite process, a voltage of 300 to 700 V is applied to a keronite electrolyte, and the magnesium plate is put in to cause a plasma reaction, and an oxide film layer is modified on the surface of the magnesium plate.

A CNT dipping step (S150) is performed in which the hydrophilic carbon nanotube (CNT) powder is added during the keronite process. In the CNT dipping step (S150), a voltage of 300 to 700 V is applied to the keronite electrolyte, the temperature of the electrolyte is about 25 ° C (for example, 24 to 26 ° C) at room temperature, 30 minutes PEO (Plasma Electrolytic Oxidation) treatment. At this time, after the porous film is formed, a hydrophilic CNT dispersion is immersed in an electrolytic bath to form CNT particles into the innumerable pores of the porous film layer. Specifically, when a magnesium plate is immersed in a dispersion in which CNT powder and water are dispersed by stirring at a constant ratio, CNT particles can be penetrated into the pores of the porous coating. The CNT is a material having a good electrical conductivity and a graphite surface in the form of a barrel-shaped dried body. The CNT has a small particle size and a specific surface area relative to a specific substance. The CNT has excellent conductivity, physical strength and thermal conductivity. Since the size is a nano-sized particle, it can be easily penetrated into the pores and is advantageous for realizing corrosion resistance and heat dissipation. The CNT immersion process (S150) is summarized in Table 5, which is compared with the conventional anodizing process of Table 6 as follows.

Voltage (V) Temperature (℃) Immersion time (min) 300 5 15 minutes 400 10 15 minutes 500 15 15 minutes 600 20 15 minutes 700 25 15 minutes

Voltage (V) Temperature (℃) Immersion time (min) 80 5 3 minutes 90 10 3 minutes 100 15 3 minutes 110 20 3 minutes 120 25 3 minutes

In the CNT immersion step, it is preferable that the electrolytic solution is adjusted up to about 25 캜 of normal temperature at about 15 캜, which is the temperature of the conventional magnesium anodizing, to form an oxide film layer at a higher temperature. This can realize the effect of enlarging the pore size at a high temperature, and thus the CNT particles can be more easily penetrated into the pores of the expanded porous film through the keronite process at room temperature.

In addition, since the thickness of the porous coating layer becomes thicker as the electrolysis time becomes longer and the current density becomes higher, the porous coating layer induces a plasma discharge of 300 to 700 V so as to be proportional to the amount of current to be supplied. ~ Time of up to 30 minutes to allow formation of a rigid porous coating layer. At this time, the process conditions of Table 5 and Table 6 were measured at a temperature range of 5 to 25 ° C in the range of 5 ° C, and the voltage at the time of existing anodizing was measured within a range of 70 to 130 V, The voltage of the process was measured within the range of 300 ~ 700V and each 100V range.

In this way, the surface of the magnesium plate having the oxide coating layer formed as the CNT particles penetrate into the pores of the porous coating layer can realize the effect of enhancing the porous heat radiation effect and the corrosion resistance, and also the magnesium plate has the predetermined color (dark gray color) The coloring effect can be realized. The heat radiation effect test according to the CNT immersion process is as follows according to the CNT immersion process conditions of Table 5 and the existing anodizing process conditions of Table 6 as follows.

Exam conditions
Mg anodizing CNT treatment after keronite process Actual temperature (℃) Contact test temperature (℃) Actual temperature (℃) Contact test temperature (℃) Measuring temperature 50 49 50 44 Temperature change -1 ℃ -6 ° C

That is, according to the heat dissipating effect test according to the present invention, the heat sink effect is improved by 5 占 폚 or more than the existing magnesium anodizing process according to the CNT immersion process according to the conditions of Table 7 in the heat sink. can confirm.

After completion of the CNT immersion process (S150), the CNT immersion process (S150) is followed by a washing process. Subsequently, a drying process (S160) for evaporating or drying the moisture remaining on the anodizing surface, . At this time, the drying is naturally dried at room temperature, but it is preferable to oven-dry by hot air heater or infrared ray drying. Further, a sealing step may be further added to cover the pores of the porous coating layer before the drying step (S160). In the case of the CNT particles, the dispersibility is good and the penetration power is excellent, but the above-mentioned sealing step is a process of filling the remaining uninfected portion, and thus the corrosion resistance of the porous coating layer can be further strengthened.

100, 200: Kitchen container using magnesium plate
40, 140: Body
80, 160: Coating layer

Claims (5)

In the magnesium anodizing method,
A pretreatment step of pretreating the magnesium plate material;
A pre-treatment step of applying a voltage of 300 to 700 V into the keronite electrolyte, placing the magnesium plate in the electrolyte to cause a plasma reaction, forming a porous coating layer on the surface of the magnesium plate to form a plurality of pores, A keronite process and a CNT immersion step in which hydrophilic CNT particles are permeated into the pores of the porous coating layer;
And removing the foreign substances generated in the step of immersing the CNTs and then evaporating or drying the moisture remaining on the surface of the magnesium plate. The method according to claim 1,
Wherein the CNT dipping step is performed under conditions of a normal temperature of 24 to 26 DEG C and an immersion time of 15 to 30 minutes. The method according to claim 1,
The pre-
A shape processing step of processing the magnesium plate material into a shape suitable for an application product;
An immersion degreasing step of retaining the surface of the magnesium plate material after the shaping step and removing organic contaminants;
A chemical etching step of removing a portion of the surface of the magnesium plate having undergone the immersion degreasing step or a portion of the surface layer such as a segregation, an oxide, or a release agent existing between particles;
A neutralization step of modifying an acid and a magnesium fluoride film formed on the surface of the magnesium plate after the chemical etching step is completed;
And a desmutting step of removing the smut of the magnesium plate material. The method according to claim 1,
Further comprising the step of sealing the pores of the porous coating layer prior to the drying step. The method according to claim 1,
The product using the magnesium plate includes a body molded into a shape suitable for the product, and a second coating layer for surface treatment of the body by the keronite process and the CNT immersion step, followed by a first coating layer and a second coating layer for nonstick prevention Wherein the magnesium anodizing method is characterized by:

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