Anti-corrosion coating composition for metals

Abstract

The present application relates to an anti-corrosion coating composition for metal, including a ternary or quaternary mixture, a method of preparing same, and an anti-corrosion coating for metal.

Description

[0001] ANTICORROSIVE COATING COMPOSITION FOR METALS

[0002] DESCRIPTION OF THE INVENTION

[0003] Technical Field

[0004] This application relates to an anti-corrosive coating composition for metals comprising a ternary or quaternary mixture, a method for its preparation, and an anti-corrosive coating for metals.

[0005] Description of the state of the art

[0006] Magnesium alloys are widely used in electronic devices, especially in products requiring weight reduction, such as video cameras. One of magnesium's characteristics is its high durability and light weight. However, magnesium is very susceptible to corrosion, forming a white oxide layer when exposed to air. This oxide layer can resemble unsightly mold to consumers, so various anti-corrosion treatment technologies are used to prevent this.

[0007] One of the most effective and widely used products is DOW7. However, the main drawback of DOW7 is that it uses highly toxic and dangerous hydrofluoric acid (HF), as well as dichromate, which is a carcinogen. European regulations have recently banned the use of DOW7, forcing the industry to seek new alternatives.

[0008] Currently, the only commercially available alternative is SurTec 650 chromitAL® TCP. Typically, a surface preparation product such as SurTec 138, SurTec 089, or SurTec 486 is required before application. However, HF is still used for these preparations. Furthermore, SurTec 650 chromitAL® TCP contains chromium(III), which is less harmful than dichromate, but is still not environmentally friendly.

[0009] Much research has been done in the area exploring various alternative coatings, including permanganate, phosphate, cerium, lanthanum, and vanadate, but these methods have not been implemented commercially.

[0010] Detailed description of the invention

[0011] The embodiments of this application are described in detail below with reference to the accompanying drawings so that those skilled in the art may readily implement them. However, this application can be embodied in many different forms and is not limited to the embodiments set forth herein. To clearly illustrate this application in the drawings, parts irrelevant to the description are omitted, and the same reference numbers are assigned to the same or similar parts throughout this specification.

[0012] Throughout this specification, when it is said that an element is located “on” another element, this includes not only the case where one element is in contact with another, but also the case where a third element is present between them.

[0013] Throughout this specification, when a part is said to “include” a component, this means that the part may also include other components without excluding other components, unless specifically stated otherwise. Throughout this specification, the terms “approximately,” “substantially,” and similar terms are used in a sense that includes values ​​close to or around the stated values, taking into account the tolerances inherent in the manufacturing process and the materials mentioned. These terms are employed to prevent unscrupulous infringers from unfairly exploiting disclosures expressed in exact or absolute values ​​for the purpose of facilitating understanding of the request. The term “step of…r” or “step of” used throughout this specification does not mean “step for.”

[0014] Throughout this specification, the term "combination(s) of these" included in the Markush form expression means a mixture or combination of one or more selected from the group consisting of the components described in the Markush form expression, and means that it includes one or more selected from the group consisting of the aforementioned components.

[0015] Throughout this specification, the description of "A and / or B" means "A, B, or A and B".

[0016] The purpose of this application is to provide an effective and environmentally friendly anti-corrosion coating that can replace conventional and harmful chemicals. The proposed coating offers a way to prevent corrosion of magnesium alloys without the use of conventional harmful chemicals. However, the problem addressed by this application is not limited to the issues mentioned above, and other unmentioned problems will become clear to those skilled in the art from the following description.

[0017] The embodiments and examples of this application are described in detail below with reference to the accompanying drawings. However, this application is not necessarily limited to these embodiments, examples, and drawings.

[0018] A first aspect of the present application provides an anti-corrosive coating composition for metals comprising a base component containing potassium dihydrogen phosphate (KH2PO4) and potassium permanganate (KMnO4); and an additional component comprising one or more selected from lanthanum nitrate (La(NO3)3), calcium nitrate (Ca(NO3)2), cene nitrate (Ce(NO3)3), sodium metavanadate (NaVO3) and yttrium nitrate (Y(NO3)3).

[0019] In an embodiment of the present application, the anti-corrosion coating composition for metals can form a coating on the metal as a single layer or multiple layers. The anti-corrosion coating composition for metals is a mixture, so that the anti-corrosion efficacy and reproducibility as a coating can be improved compared to when each component is used separately, and the coating layer can be formed as a single layer or multiple layers. Specifically, potassium dihydrogen phosphate (KH₂PO₄) is a phosphate-based compound used to form a phosphate conversion coating on the metal surface. This process forms an insoluble phosphate metal on the magnesium surface, which can prevent corrosion.Potassium permanganate (KMnO4) is a strong oxidizing agent and can form a manganese-based conversion coating on the metal surface, so treatment with potassium permanganate can inhibit corrosion by forming manganese oxide on the metal surface.

[0020] Furthermore, lanthanum nitrate (La(NO3)3) can provide lanthanum ions to form a lanthanum-based conversion coating on the metal surface, thus providing high corrosion resistance and excellent electrochemical stability. Calcium nitrate (Ca(NO3)2) can provide calcium ions to form a calcium-based conversion coating on the metal surface, thus improving corrosion resistance. Ce(NO3) nitrate (Ce(NO3)) can form a cenooxide film on the metal surface through an oxidation reaction of cenooxide ions. This dense and stable oxide film inhibits corrosion by protecting the metal from the external environment.Sodium metavanadate (NaVO3) is a vanadium-based compound that can inhibit corrosion by forming vanadium oxide on the magnesium surface. This vanadium oxide then acts as a protective layer, forming an anti-corrosive coating. Yttrium nitrate (Y(NO3)3) provides yttrium ions to form a yttrium-based conversion coating on the magnesium surface. This yttrium compound offers strong corrosion resistance and excellent anti-corrosive performance.

[0021] In an embodiment of the present application, the basic component may be formed as one layer, and the additional component may be formed as another layer.

[0022] In an embodiment of the present application, one or more selected from lanthanum nitrate (La(NO3)3), calcium nitrate (Ca(NO3)2), cerium nitrate (Ce(NO3)3), sodium metavanadate (NaVO3) and yttrium nitrate (Y(NO3)3), together with the basic component, may be formed as a layer, and the additional component may be formed as another layer.

[0023] In an embodiment of the present application, the basic component can be formed as a layer, and a mixture of lanthanum nitrate (La(NO3)3) and calcium nitrate (Ca(NO3)2) can be formed as another layer.

[0024] In an embodiment of this application, the metal may include, but is not limited to, one or more of magnesium, aluminum, iron, zinc, copper, and their alloys. Specifically, the metal may be magnesium.

[0025] In an embodiment of this application, the content ratio of the basic component to the additional component may be 2:1 to 1:1. The content ratio may be measured on a g / L basis, and more specifically, the content ratio of the basic component to the additional component may be 2:1 or 1:1.

[0026] In one embodiment of the present application, the content of potassium dihydrogen phosphate (KH2PO4), potassium permanganate (KMnO4), lanthanum nitrate (La(NO3)3), calcium nitrate (Ca(NO3)2), cerium nitrate (Ce(NO3)3), sodium metavanadate (NaVO3), and yttrium nitrate (Y(NO3)3) may be from 2 g / L to 5 g / L. The content of the basic component or the additional component may be from 2 g / L to 5 g / L, and the desired efficacy may be achieved even at 2 g / L. Similar efficacy may be achieved by increasing the concentration to 5 g / L, as in the examples below.

[0027] In one embodiment of the present application, the content ratio of potassium dihydrogen phosphate (KH2PO4) to potassium permanganate (KMnO4) may be from 6:4 to 4:6. The content ratio may be measured on a g / L basis, and more specifically, the content ratio of potassium dihydrogen phosphate (KH2PO4) to potassium permanganate (KMnO4) may be 5:5.

[0028] A second aspect of this application provides a method for producing the anti-corrosive coating for metals, which includes performing one or more selected processes of cleaning, polishing, and etching the metal; and coating the metal with the anti-corrosive coating composition for metals according to the first aspect.

[0029] The production method for the anti-corrosive coating for metals can be carried out using a conventional coating formation method, and more specifically, through a chemical conversion coating procedure.

[0030] In an embodiment of the present application, the coating may be made in such a way as to form a single or multiple layer.

[0031] In an embodiment of the present application, the coating may be carried out by a selected method of chemical conversion coating, including immersion, spraying and sol-gel coating, and physical coating, including painting, electroplating and physical vapor deposition.

[0032] A third aspect of the present application provides an anti-corrosive coating for metals, wherein the anti-corrosive composition for metals according to the first aspect forms a coating layer.

[0033] In an embodiment of this application, the coating layer thickness may be from 10 µm to 20 µm. Specifically, the coating layer thickness may be from 10 µm to 20 µm, 10 µm to 18 µm, 10 µm to 16 µm, 10 µm to 14 µm, 10 µm to 12 µm, 12 µm to 20 µm, 12 µm to 18 µm, 12 µm to 16 µm, 12 µm to 14 µm, 14 µm to 20 µm, 14 µm to 18 µm, 14 µm to 16 µm, or 14 µm to 16 µm, but is not limited to these measurements. In an embodiment of this application, the coating layer may be a single or multiple layer.

[0034] In an embodiment of the present application, the basic component can be formed as one layer and the additional component can be formed as another layer.

[0035] In an embodiment of the present application, one selected from lanthanum nitrate (La(NO3)3), calcium nitrate (Ca(NO3)2), cerium nitrate (Ce(NO3)3), sodium metavanadate (NaVO3) and yttrium nitrate (Y(NO3)3), and the basic component can be formed as one layer, and the additional component can be formed as another layer.

[0036] In an embodiment of the present application, the basic component can be formed as a layer, and a mixture of lanthanum nitrate (La(NO3)3) and calcium nitrate (Ca(NO3)2) can be formed as another layer.

[0037] Through this, the following effects can be achieved:

[0038] First, this application provides an environmentally friendly anti-corrosion coating for metals. Conventional anti-corrosion treatments primarily use toxic chemicals, resulting in serious risks to the environment and human health. However, this application uses non-toxic materials such as permanganate, phosphate, calcium, cerium, vanadium, yttrium, and lanthanum to minimize environmental pollution. This can be of great help in protecting the environment from harmful chemicals, ensuring worker safety, and complying with stringent environmental regulations in regions such as Europe.

[0039] Second, this application provides excellent anti-corrosion performance. In particular, this application demonstrates a better corrosion inhibition effect than conventional commercial anti-corrosion treatments (D0W7 and SurTec 650 chromitAL® TCP). Furthermore, the combination of the base components KH2PO4 and KMnO4 can significantly reduce the corrosion current density, effectively preventing corrosion of magnesium alloys. This contributes to extending the service life of magnesium alloys and improving product durability.

[0040] Third, this application can increase the reproducibility of the coating treatment. Not only is the anti-corrosion performance important, but also the reproducibility of the coating treatment, and the combination of the base components KH₂PO₄ and KMnO₄ in this application plays a significant role in increasing reproducibility. This ensures consistent coating quality and can maintain stable performance even during mass production.

[0041] Fourth, this application can maximize the efficiency of the anti-corrosion treatment. In particular, this application exhibits a high anti-corrosion effect even at low concentrations, thereby reducing the amount of chemicals used. This not only reduces costs but also decreases chemical consumption, thus minimizing the environmental impact.

[0042] Fifth, the coating described in this application exhibits stable performance even under diverse environmental conditions. Salt spray tests and long-term environmental corrosion tests have demonstrated that the coating described in this application exhibits excellent durability even under extreme conditions. This suggests its potential application in magnesium alloy products used in various industrial fields, such as automobiles, aircraft, and electronic devices.

[0043] However, it is evident that the effects implemented by this application are not limited to the contents described above and include effects that can be foreseen by those experts in the field.

[0044] Brief description of the figures.

[0045] FIG. 1 is a graph showing the polarization curve (Tafel) for coatings of KH2PO4, KMnO4 and KH2PO4+ KMnO4 (all material concentrations are 2 g / L, deposition times and temperatures are indicated on the label).

[0046] FIG. 2 is a graph showing the polarization curve (Tafel) for coatings of KMnO4+ La(NO3)3 and KH2PO4+ KMnO4 / La(NO3)3 (all concentrations of materials are 2 g / L, deposition times and temperatures are indicated on the label).

[0047] FIG. 3 is a graph showing the polarization curve (Tafel) for coatings of KMnO4+ La(NO3)3, KMnO4+ Ce(NO3)3 and KMnO4+ La(NO3)3+ Ce(NO3)3 (all concentrations of materials are 2 g / L, deposition times and temperatures are indicated on the label).

[0048] FIG. 4 is a graph showing the polarization curve (Tafel) for coatings of La(NO3)3, Ce(NO3)3 and La(NO3)3+ Ce(NO3)3 (all material concentrations are 2 g / L, deposition times and temperatures are indicated on the label).

[0049] FIG. 5 is a graph showing the polarization curve for magnesium treated with an anti-corrosive composition (all material concentrations are 2 g / L, each deposition time is 5 minutes and the temperature is 65 °C).

[0050] FIG. 6 is a box plot of the corrosion current density of magnesium treated with an anti-corrosive composition (all material concentrations are 2 g / L, each deposition time is 5 minutes and the temperature is 65 °C).

[0051] FIG. 7 is a graph showing the shift in the cathodic or anodic direction of the corrosion potential of magnesium treated with various anti-corrosive compositions (the vertical line marks the boundary of the zone at ±85 mV).

[0052] FIG. 8 is a graph showing the polarization curve for magnesium treated with anti-corrosive compositions in different orders (this means treatment in different baths for 5 minutes. Understand 7' independent baths).

[0053] FIG. 9 is a scatter plot of the electrochemical properties of anticorrosive compositions treated in different orders. The intersection of the axes corresponds to the average electrochemical properties for the commercial treatment SurTec 650 chromitAL® TCP.

[0054] FIG. 10 is a graph showing the polarization curve for magnesium treated with an anti-corrosive composition at low concentration (2 g / L) and high concentration (5 g / L).

[0055] Figure 11 is a scatter plot of the electrochemical properties of an anticorrosive composition applied at two different concentrations. The intersection of the axes corresponds to the average electrochemical properties for the commercial treatment SurTec 650 chromitAL® TCP. The intersection of the red lines corresponds to the average electrochemical properties of the previous treatment called D0W7. Figure 12 is a photograph showing the results of a corrosion test in a salt spray environment after 7 days on a magnesium sample with a smooth surface treated with an anticorrosive composition.

[0056] FIG. 13 is a photograph showing the results of a corrosion test in a salt spray environment after 84 days on a magnesium sample with a smooth surface coated with paint treated with an anti-corrosive composition.

[0057] FIG. 14 is a scanning electron micrograph of a magnesium sample with a smooth surface treated with an anti-corrosive composition.

[0058] FIG. 15 is a graph showing the energy dispersive X-ray analysis of a magnesium sample treated with KH2PO4+ KMnO4 / La(NO3)3+ Ca(NO3)2.

[0059] FIG. 16 is a scanning electron micrograph taken to determine the coating thickness on a magnesium sample with an initially smooth surface treated with an anti-corrosive composition.

[0060] Examples of implementation

[0061] Example. Production and confirmation of the effectiveness of the anti-corrosion coating for metals

[0062] 1. Production of the anti-corrosive coating for metals First, magnesium was prepared as a sample, and the front side was sanded using 600 grit sandpaper and then sanded with 2000 grit sandpaper. Then, the surface was washed with acetone and water.

[0063] As a subsequent alkaline washing step, the sample was immersed in 75 mL of a mixed solution of 50 g / L NaOH and 10 g / L Na3PO4·12H2O. After holding it at 60 °C ± 5 °C for 10 min, the sample was transferred to a beaker containing a pickling solution.

[0064] As a pickling step, the sample was immersed in 60 mL of a mixed solution of 195 mL / L of CH3COOH and 40 g / L of NaNO3 for 10 seconds at room temperature. Subsequently, the sample was transferred to a beaker containing a coating solution of each composition. As a coating step, the sample was immersed in the solution at 65 °C for 5 min to ensure that the entire surface was coated. When the coating required two different treatments, each treatment was carried out for 5 min, for a total of 10 min (here, the pH of the coating solution was checked to be 4 and adjusted using phosphoric acid or potassium hydroxide when necessary).

[0065] 2. Experimental conditions to confirm the coating's effectiveness. Data collection was performed using Gamry Instruments Framework software version 7.8.2, and the open-circuit voltage of each sample was measured for 30 min to determine the reference voltage range. Additionally, to generate a polarization curve, a scan rate of 1 mV / s and a sodium chloride solution with a concentration of 0.1 mol / L were used. A platinum mesh was used as the counter electrode, and a silver / silver chloride (Ag / AgCl / KCl) electrode containing potassium chloride (KCl) at a concentration of 3 mol / L was used as the reference electrode.

[0066] Furthermore, the samples were characterized by determining their morphology and performing elemental analysis of the surface. Morphology was evaluated using scanning electron microscopy (SEM), which allows for detailed visualization and description of the sample's surface structure. Elemental analysis of the surface was performed using energy-dispersive X-ray spectroscopy (EDX), which enables the identification of the elements present in the sample. This elemental analysis provides detailed information on the chemical composition of the sample's surface, revealing its characteristics and important data for understanding its properties. An integrated X-ray scattering analysis system equipped with a Hitachi S-300 scanning electron microscope and an INCA x-scope (Oxford Instruments) was used for the analysis. An accelerating voltage of 15.0 kV was applied to the electron beam during the analysis.A takeoff angle of 35° was set to optimize the characteristic X-rays emitted from the sample, and an elapsed time of 100 seconds was set for the collection of X-ray spectrum data.

[0067] The anti-corrosion effectiveness was determined based on evaluation results showing a significant reduction in the corrosion rate, and this test was performed according to ASTM B117. Each sample with an anti-corrosion coating was exposed for 168 h at a temperature of 35 °C in an atmosphere composed of 95% deionized water and 5% NaCl. Initially, magnesium samples with both smooth and rough surfaces were used. Each sample was photographed daily to assess the presence of surface pitting, as specified in the standard. Magnesium parts coated with the commercial anti-corrosion treatments SurTec 650 chromitAL® TCP and D0W7 were used as controls.

[0068] In addition, for environmental corrosion testing of the coated magnesium samples, each sample was exposed to a sprayed saltwater mist for 2,000 h. The evaluation of the samples included observing the presence of pitting and blistering corrosion on the surface, which was documented with photographic evidence. Magnesium parts coated with the commercially available painted anti-corrosion treatments SurTec 650 chromitAL® TCP and D0W7 were used as controls.

[0069] Experimental Example 1. Importance of using a mixture of potassium dihydrogen phosphate (KH2PO4) and potassium permanganate (KMnO4)

[0070] A multifactorial analysis was performed on coatings containing the components shown in Table 1 below (FIG. 1).

[0071] [Table 1]

[0072] Figure 1 confirms that measurement reproducibility was achieved using only KH₂PO₄, whereas this was not the case with KMnO₄. However, the addition of KMnO₄ is important because it provides a crucial chemical element (manganese) to the coating. Therefore, using KH₂PO₄ + KMnO₄ resulted in good anti-corrosion activity and improved reproducibility. Furthermore, a deposition time of 5 minutes and a deposition temperature of 65 °C were confirmed to be appropriate.

[0073] In general, the reproducibility of Tafel's measurements was reduced when KH2PO4 was not used. In FIG. 2, very low reproducibility was observed in the samples when only KMnO4 and La(NO3)3 were used. On the other hand, greater reproducibility was achieved in the experiment when KH2PO4 was added to the solution.

[0074] Instability and a lack of reproducibility were also observed in the measurements when KH₂PO₄ was not used in combinations with other materials, times, and temperatures. In Figure 3, the experiment that omitted KH₂PO₄ showed lower reproducibility. Furthermore, Figure 4 confirms that reproducibility is poor even when only rare-earth materials are used.

[0075] Therefore, based on all these measurements, it was confirmed that KH2PO4 and KMnO4 consistently achieve excellent anti-corrosive effects and coating reproducibility when used in combination.

[0076] Experimental Example 2. Effects of ternary and quaternary mixtures

[0077] Tafel measurements were used to determine the effects of ternary and quaternary mixtures, and the measurements for each sample were repeated three times according to Table 2 below (the + sign indicates the presence of a material and the - sign indicates the absence of a material. All compounds were applied at a concentration of 2 g / L, at a deposition temperature of 65 °C and 5 minutes for each immersion step).

[0078] [Table 2]

[0079] Figure 5 shows the measurement results, from which the corrosion potential and corrosion current were determined. Figure 6 shows the observed corrosion current for various treatments. This current was derived from statistical analysis using Tafel analysis performed on three measurements of each sample. All treatments showed anti-corrosive effects, with samples H and I exhibiting the most effective performance. Samples J through M showed similar levels of effect. Importantly, all evaluated treatments showed better anti-corrosive effects than the untreated metal samples and the commercial treatments D0W7 and SurTec 650 chromitAL® TCP. Among the ternary mixtures, sample E showed anti-corrosive efficacy similar to that of the quaternary mixture. It is also important to note that very low concentrations of chemicals were used in all samples.

[0080] When comparing the changes in corrosion potential for the metal samples, it was observed that most of the coatings exhibited a mixed or anodic inhibition mechanism (FIG. 7).

[0081] Experimental Example 3. Effect of the order of application of the coating composition

[0082] It was investigated whether varying the order of application of the components in the coating composition would affect the anticorrosive capacity. Figure 8 shows the resulting polarization curve. The dispersion of the corrosion potential and corrosion current density is shown in Figure 9. Some measurements showed greater dispersion depending on the order of application.

[0083] The order of application was significant for two treatments, but not significant for the other two treatments. In particular, in the case of KH2PO4+ KMnO4 / La(NO3)3+ Ca(NO3)2 among the samples, the order of application was not significant (Table 3).

[0084] [Table 3]

[0085] Experimental Example 4. Effect of concentration

[0086] The effect of concentration was confirmed after increasing the concentration of the chemicals in the sample from 2 g / L to 5 g / L in the deposition mixture. The measurement values ​​obtained are shown in FIG. 10.

[0087] Figure 11 shows the data dispersion for corrosion current density and corrosion potential. For the KH₂PO₄ + KMnO₄ / La(NO₃)₃ + Ca(NO₃)₂ sample, the data dispersion was low. Furthermore, this treatment has the most negative corrosion current density values, indicating that it provides the best protection against corrosion among the treatments analyzed.

[0088] The inhibition rate was obtained from previous corrosion measurements, and it was observed that the anti-corrosive effect was similar even when the concentration was increased. Therefore, it was sufficiently effective even at a low concentration, and it was confirmed to be environmentally friendly because it consumes fewer chemicals. Specifically, for the KH₂PO₄ + KMnO₄ / La(NO₃)₃ + Ca(NO₃)₂ sample, increasing the concentration did not have a significant effect on the inhibition rate (Table 4).

[0089] [Table 4]

[0090] Experimental Example 5. Salt Spray Analysis

[0091] Figure 12 shows the coating performance in the salt spray analysis. After 7 days of analysis, the best performing sample was the KH2PO4+ KMnO4 / La(NO3)3+ Ca(NO3)2 coating.

[0092] In addition, black paint was applied over the coating and a salt spray analysis was performed for 84 days (FIG. 13). The best performance was shown in the KH2PO4+ KMnO4 / La(NO3)3+ Ca(NO3)2 sample.

[0093] Experimental Example 6. Surface characterization analysis, energy-dispersive X-ray analysis, and surface thickness measurement

[0094] According to the SEM images in FIG. 14, most of the samples showed good surface coating. In particular, the KH2PO4+ KMnO4 / La(NO3)3+ Ca(NO3)2 sample showed a uniform coating on the magnesium surface. Furthermore, the presence of the coating composition species on the surface of the metallic sample was confirmed by energy-dispersive X-ray spectroscopy analysis, as shown in FIG. 15 and Table 5. [Table 5]

[0095] Finally, the thickness of the deposited coating layer was measured. For the sample KH2PO4+ KMnO4 / La(NO3)3+ Ca(NO3)2, a thickness of approximately 14 pm was observed.

[0096] The foregoing description of the present application is for illustrative purposes only, and it shall be understood by those skilled in the art that the forms may be readily modified to other specific forms without changing the spirit and essential characteristics of the invention. Therefore, it should be understood that the forms described above are illustrative in all respects and not restrictive. For example, each component described as a unique type may be implemented in a distributed form, and likewise, the components described as distributed may be implemented in a combined form.

[0097] The scope of this application is indicated by the following claims instead of the preceding description, and all changes or modifications arising from the meaning and scope of the claims and their equivalents shall be construed as being included within the scope of this application.

[0098] Industrial Application

[0099] The present invention can be applied to various industrial fields in which metal is used.

Claims

CLAIMS 1. An anti-corrosion coating composition for metal comprising: - a basic component that includes potassium dihydrogen phosphate (KH2PO4) and potassium permanganate (KMnO4); and - an additional component that includes one or more selected from lanthanum nitrate (La(NO3)3), calcium nitrate (Ca(NO3)2), cerium nitrate (Ce(NO3)3), sodium metavanadate (NaVO3) and yttrium nitrate (Y(NO3)3).

2. The coating composition of claim 1, wherein the coating is formed on the metal as a single layer or multiple layers.

3. The coating composition of claim 2, wherein the basic component is formed as one layer, and the additional component is formed as another layer.

4. The coating composition of claim 2, wherein one selected from lanthanum nitrate (La(NO3)3), calcium nitrate (Ca(NO3)2), cerium nitrate (Ce(NO3)3), sodium metavanadate (NaVO3), and yttrium nitrate (Y(NO3)3) and the basic component are formed as one layer, and the additional component is formed as another layer.

5. The coating composition of claim 2, wherein the basic component is formed as a layer, and a mixture of lanthanum nitrate (La(NO3)3) and calcium nitrate (Ca(NO3)2) is formed as another layer.

6. The coating composition of claim 1, wherein the metal includes one or more selected from magnesium, aluminum, iron, zinc, copper and alloys thereof.

7. The coating composition of claim 1, wherein the ratio of potassium dihydrogen phosphate (KH2PO4) to potassium permanganate (KMnO4) is 6:4 to 4:

6.

8. The coating composition of claim 1, wherein the ratio in content of the basic component and the additional component is 2:1 to 1:

1.

9. The coating composition of claim 1, wherein the content of potassium dihydrogen phosphate (KH2PO4), potassium permanganate (KMnO4), lanthanum nitrate (La(NO3)3), calcium nitrate (Ca(NO3)2), cerium nitrate (Ce(NO3)3), sodium metavanadate (NaVO3), and yttrium nitrate (Y(NO3)3) is from 2 g / L to 5 g / L.

10. A method for producing an anti-corrosive coating for metal, comprising: performing one or more selected processes of cleaning, polishing, and etching the metal; and coating the metal with the anti-corrosive coating composition of claim 1.

11. The method of claim 10, wherein the coating is carried out in such a way that the coating is formed as a single layer or multiple layers.

12. The method of claim 10, wherein the coating is carried out by a selected chemical conversion coating method including immersion, spraying and sol-gel coating, and physical coating, including painting, electrodeposition and physical vapor deposition.

13. An anti-corrosive coating for metal wherein the anti-corrosive coating composition of claim 1 forms a coating layer.

14. The coating of claim 13, wherein the coating layer has a thickness of 10 pm to 20 pm.

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