KR20040031481A - A Post-Treatment Method of Cold Rolled Steel Sheets with Improved Corrosion Resistance - Google Patents

A Post-Treatment Method of Cold Rolled Steel Sheets with Improved Corrosion Resistance Download PDF

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KR20040031481A
KR20040031481A KR1020020060939A KR20020060939A KR20040031481A KR 20040031481 A KR20040031481 A KR 20040031481A KR 1020020060939 A KR1020020060939 A KR 1020020060939A KR 20020060939 A KR20020060939 A KR 20020060939A KR 20040031481 A KR20040031481 A KR 20040031481A
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cold rolled
rolled steel
corrosion resistance
steel sheet
film
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KR1020020060939A
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Korean (ko)
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김영근
윤정모
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주식회사 포스코
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Publication of KR20040031481A publication Critical patent/KR20040031481A/en

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    • CCHEMISTRY; METALLURGY
    • C25ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25DPROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D9/00Electrolytic coating other than with metals
    • C25D9/02Electrolytic coating other than with metals with organic materials
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08GMACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G73/00Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
    • C08G73/02Polyamines
    • C08G73/026Wholly aromatic polyamines
    • C08G73/0266Polyanilines or derivatives thereof

Abstract

PURPOSE: A cold rolled strip posttreatment method for improving corrosion resistance is provided in which a conductive polyaniline thin film is formed on cold rolled strip so that the cold rolled strip displays superior corrosion resistance and is environmentally friendly. CONSTITUTION: The cold rolled strip posttreatment method comprises the process of forming a conductive polyaniline polymer coating film on cold rolled strip by electropolymerizing a solution having a temperature of 30 to 70 deg.C in which oxalic acid and aniline are mixed in a weight ratio of 90:10 to 70:30 by electricity quantity of 0.1 to 10 coulombs, wherein thickness of the coating film is 0.05 to 0.5 mm, and wherein current density during electrolysis is 1 to 100 mA/cm¬2.

Description

내식성 향상을 위한 냉연강판의 후처리 방법{A Post-Treatment Method of Cold Rolled Steel Sheets with Improved Corrosion Resistance}A Post-Treatment Method of Cold Rolled Steel Sheets with Improved Corrosion Resistance}

본 발명은 냉연강판의 내식성을 개선하기 위해 냉연강판에 전도성 고분자 피막을 형성하는 냉연강판의 후처리 방법에 관한 것이다. 보다 상세하게 본 발명은 자동차용 및 가전용 강판 등에 사용되는 냉연강판의 내식성을 개선하기 위해 옥살산과 아닐린(aniline)의 혼합용액을 전해중합하여 냉연강판에 전도성 폴리아닐린 고분자피막을 형성하는 냉연강판의 후처리 방법에 관한 것이다.The present invention relates to a post-treatment method of a cold rolled steel sheet forming a conductive polymer film on the cold rolled steel sheet to improve the corrosion resistance of the cold rolled steel sheet. More specifically, the present invention provides a post-cold rolled steel sheet for forming a conductive polyaniline polymer film on a cold rolled steel sheet by electrolytic polymerization of a mixed solution of oxalic acid and aniline to improve the corrosion resistance of a cold rolled steel sheet used for automobile and home appliances. It is about a processing method.

냉연강판은 표면이 미려하고 가공성, 용접성 및 도장성이 우수하여 자동차용 혹은 가전용 강판으로 널리 사용되어 왔다. 그러나, 이는 산소와의 친화력이 커서 대기중의 산소나 수분등과 접촉하면 쉽게 부식되는 단점을 갖는다.Cold rolled steel sheet has a beautiful surface, excellent workability, weldability and paintability has been widely used as automotive or household steel sheet. However, this has a disadvantage in that it has a high affinity with oxygen and is easily corroded when contacted with oxygen or moisture in the atmosphere.

이와 같은 철의 부식성을 지연시키기 위하여 철강사에서는 표면에 방청유를 도포하여 수요가에게 공급하고 수요가는 알칼리 탈지라는 과정을 거쳐 방청유를 제거한 다음 원하는 형태로 가공한 후 용도에 맞게 페인트 칠을 하여 사용한다.In order to delay the corrosiveness of iron, steel companies apply rust-preventive oil to the surface and supply it to demand, and remove the rust-preventive oil through a process called alkali degreasing, process it into a desired form, and paint it according to its purpose.

자동차용 강판의 경우는 내식성을 향상시키기 위하여 철강사에서 주로 아연 및 아연합금을 도금하여 공급하지만 도금강판은 가공성, 용접성, 도장성 등이 일반 냉연강판에 비하여 열세이기 때문에 내식성을 크게 요구하지 않는 환경에서는 아연등이 도금되지 않은 냉연강판이 자동차용 강판등으로 사용한다.In the case of automotive steel plates, zinc and zinc alloys are mainly supplied by steel companies to improve their corrosion resistance. However, in the environment where galvanized steel sheets are inferior to general cold rolled steel sheets, workability, weldability, and paintability are inferior to general cold rolled steel sheets. Cold rolled steel without zinc plating is used as steel sheet for automobiles.

그러나, 방청유가 도포된 냉연강판이라도 장기간 방치하거나 운송할 경우 또는 대기중에 장기간 노출되면 방청유가 증발하거나 흘러내려 방청유의 방청성이 떨어지면서, 강판이 공기중의 수분이나 산소와 접촉하게 되고 이로 인하여 강판표면에 산화물이 주성분인 녹이나 얼룩이 형성된다. 이 산화물은 FeO, Fe2O3, Fe3O4등으로 구성되어 있으며 사용분위기나 시기에 따라 산화물의 종류, 두께, 색상 및 소지와의 접착력 등이 달라진다. 이와 같은 산화물이 형성되면 강판 본래의 특성이 변화되어 외관이 불량해지는 것은 물론 심할 경우에는 강판에 구멍이 생겨 결국은 사용할 수 없는 지경에 이르게 된다. 자동차용 강판의 경우 녹을 제거할 수 있는 설비가 없기 때문에 도장 후 얼룩이나 도막박리 등 심각한 문제를 야기함으로 사용할 수 없게 되고, 가전용 강판의 경우 또한 도막 부풀음이나 도막이 박리되는 등의 문제가 유발된다.However, even when cold-rolled steel sheet coated with rust preventive oil is exposed to long-term exposure or long-term exposure to the atmosphere, the rust preventive oil evaporates or flows down and the rust preventive property of the rust preventive oil is degraded. Rust or spots are formed mainly by oxides. The oxide is composed of FeO, Fe 2 O 3 , Fe 3 O 4 and the like, depending on the atmosphere and time of use, the type, thickness, color, and adhesion of the oxide to the base varies. When such an oxide is formed, the original properties of the steel sheet are changed, thereby deteriorating the appearance, and in severe cases, holes are formed in the steel sheet, which eventually leads to an unusable diameter. In the case of automotive steel sheet, since there is no facility for removing rust, it cannot be used because it causes serious problems such as staining or peeling of the coating film after coating, and in the case of home appliance steel sheets, problems such as swelling of the coating film and peeling of the coating film are also caused.

또한, 방청유를 도포하면 수요가들은 탈지시 폐수처리를 위한 환경적인 부하가 초래되고 이에 따른 경제적 부담 및 작업성 열화가 초래된다.In addition, the application of rust preventive oils leads to environmental burdens for wastewater treatment when degreasing, resulting in economic burden and deterioration of workability.

본 발명은 상기와 같은 문제를 해결하기 위하여 제안된 것으로서, 우수한 내식성을 나타내며 또한, 환경 친화적인 냉연강판의 후처리 방법을 제공하는 것이다.The present invention has been proposed to solve the above problems, and to provide a post-treatment method of cold rolled steel sheet which exhibits excellent corrosion resistance and is environmentally friendly.

도 1은 본 발명의 실시예에 의한 전기량 변화에 따른 부식전위 변화를 나타내는 그래프이며,1 is a graph showing a change in corrosion potential according to a change in electric quantity according to an embodiment of the present invention.

도 2a는 전도성 폴리아닐린 고분자 피막처리되지 않은 냉연강판의 염수분무 시험된 표면상태의 광학현미경 관찰결과를 나타내는 사진이며,Figure 2a is a photograph showing the results of optical microscopy observation of the surface state of the salt spray test of the conductive polyaniline polymer untreated cold rolled steel sheet,

도 2b는 발명예 1의 전도성 폴리아닐린 고분자 피막처리된 냉연강판의 염수분무 시험된 표면상태의 광학현미경 관찰결과를 나타내는 사진이다.Figure 2b is a photograph showing the optical microscope observation results of the salt spray test surface state of the conductive polyaniline polymer film-treated cold rolled steel sheet of Inventive Example 1.

본 발명에 의하면,According to the invention,

옥산살과 아닐린이 90:10~70:30 중량비로 혼합된 30~70oC의 용액을 0.1~10쿠울롱(Coulomb)의 전기량으로 전해중합하여 냉연강판에 전도성 폴리아닐린 고분자 피막을 형성하는 냉연강판의 후처리 방법이 제공된다.A cold rolled steel sheet that forms a conductive polyaniline polymer film on a cold rolled steel sheet by electrolytically polymerizing a solution of 30 to 70 o C mixed with oxalate and aniline in a weight ratio of 90:10 to 70:30 at an electric quantity of 0.1 to 10 coulombs. A post-treatment method of is provided.

이하, 본 발명에 대하여 상세히 설명한다.EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

본 발명은 옥살산과 아닐린의 혼합용액을 전기분해하여 냉연강판상에 전도성 폴리아닐린 고분자 피막을 형성함으로써 냉연강판에 우수한 내식성이 부여된다. 또한, 본 발명의 방법은 이에 사용되는 물질이 유해하지 않은 것으로 친환경적이다.In the present invention, excellent corrosion resistance is imparted to the cold rolled steel sheet by forming a conductive polyaniline polymer film on the cold rolled steel sheet by electrolyzing a mixed solution of oxalic acid and aniline. In addition, the method of the present invention is environmentally friendly that the material used therein is not harmful.

본 발명에 의한 형성된 전도성 폴리아닐린 고분자 피막을 갖는 냉연강판은 자동차용 및 가전용 강판으로 사용될 수 있다.Cold rolled steel sheet having a conductive polyaniline polymer film formed according to the present invention can be used as a steel sheet for automotive and home appliances.

철강에 대한 표면처리 방법으로는 크게 (1) 사용환경과의 상호작용을 방지하기 위한 장벽(barrier) 코팅, (2) 소지금속을 희생방식 형태로 보호하는 음극방식 코팅, 그리고, (3) 크로메이트 처리와 같은 중금속 산화물의 형성 등 부동태화에 의한 화학처리등이 있다. 장벽코팅 방법은 철강보다 전기화학적으로 귀(noble)한 금속을 두껍게 코팅하거나 유기수지와 같은 절연물질을 코팅하는 방법으로서 극히 일부의 목적으로만 사용이 가능하다. 음극방식 코팅은 강판에 아연과 같은 전기화학적으로 철 보다 비(base)한 금속을 적게는 20g/m2에서 많게는 500g/m2까지 도금하여 부식환경에 강판이 노출되었을 때 아연이 철 보다 먼저 부식되어 철강소지를 보호하는 것으로, 그 용도가 다양할 뿐만 아니라 일반적으로 사용되고 있다. 그러나 이 방법 또한, 작업이 번거롭고 가격이 고가이며 일반 냉연강판에 비하여 용접성, 가공성, 도장성이 떨어지는 단점이 있다. 마지막으로 부동태화를 통한 화학처리 방법은 크로메이트 처리와 같이 중금속 산화물 피막을 형성시키는 방법으로 내식성은 뛰어나나 환경에 매우 유해하므로 현재는 그 사용이 규제되고 있다.Surface treatment methods for steel include (1) barrier coatings to prevent interaction with the environment, (2) sacrificial coatings to protect base metals, and (3) chromate. And chemical treatment by passivation, such as formation of heavy metal oxides such as treatment. The barrier coating method is a method of thickly coating an electrochemically noble metal than steel or an insulating material such as an organic resin and can be used for only a few purposes. Cathodic coatings plate electrolytically base metals, such as zinc, from as little as 20 g / m 2 to as much as 500 g / m 2 . It is used to protect steel materials, and its use is not only diverse but also commonly used. However, this method also has disadvantages in that the work is cumbersome, expensive, and inferior in weldability, processability, and paintability compared to general cold rolled steel sheets. Finally, the chemical treatment method through passivation is a method of forming a heavy metal oxide film, such as chromate treatment, excellent corrosion resistance but very harmful to the environment, the use is currently regulated.

이에 따라, 본 발명에서는 냉연강판에 내식성을 부여하는 새로운 방법으로써, 냉연강판에 옥살산과 아닐린의 혼합용액을 전해중합하여 냉연강판에 전도성 고분자 물질인 폴리아닐린 박막을 형성한다.Accordingly, in the present invention, as a new method of imparting corrosion resistance to the cold rolled steel sheet, electrolytic polymerization of a mixed solution of oxalic acid and aniline on the cold rolled steel sheet forms a polyaniline thin film, which is a conductive polymer material, on the cold rolled steel sheet.

전도성 고분자 물질인 폴리아닐린은 매우 작은 입자로 비전도도는 5S/m이며 박막은 투명한 녹색을 띠는 레독스 활성금속(redox-active metal)으로서 환원조건하에서는 노랑색으로, 산화조건에서는 청색을 띄게 된다.Polyaniline, a conductive polymer material, is a very small particle, has a non-conductivity of 5 S / m, and the thin film is a reddish-active metal having a transparent green color, yellow under reducing conditions, and blue under oxidizing conditions.

폴리아닐린은 아닐린의 산화 중합에 의해 합성되는데 일반적으로 화학적인 중합(chemical polymerization)이 이용될 수 있으나, 화학적 산화 중합은 대량 생산이 가능하지만 중합 반응을 제어하기 용이하지 않음으로 전도도 등에서 불리한 면이 있다.Although polyaniline is synthesized by oxidative polymerization of aniline, chemical polymerization may be generally used, but chemical oxidative polymerization may be mass-produced, but it may be disadvantageous in conductivity because it is not easy to control the polymerization reaction.

폴리아닐린 피막의 부식방지 기구로는 i) 고분자 피막에 의한 산소, 수분 등의 침투 방지 효과, ⅱ) 하부 금속과의 계면에 금속 산화 피막 형성, 및 ⅲ) 금속 표면에 부착되어 높은 산화 전위를 형성하여 금속에서 산화제로의 전자 이동을 억제하는 등의 세가지 이론이 제시되고 있으며, 이러한 효과는 동시에 발생되는 것으로 이해된다.Corrosion prevention mechanisms for polyaniline coatings include: i) the prevention of penetration of oxygen, moisture, etc. by the polymer coating; ii) the formation of metal oxide films at the interface with the underlying metal; Three theories have been proposed, including the suppression of electron transfer from metal to oxidant, and it is understood that these effects occur simultaneously.

본 발명에 의한 냉연강판상에 전도성 고분자 물질인 폴리아닐린 피막의 형성은 옥살산과 아닐린 혼합용액(이하, 단지 "혼합용액"이라 한다.)의 전해중합으로 형성된다.The formation of the polyaniline film, which is a conductive polymer material, on the cold rolled steel sheet according to the present invention is formed by electrolytic polymerization of an oxalic acid and aniline mixed solution (hereinafter only referred to as "mixed solution").

혼합용액은 옥살산과 아닐린을 90:10~70:30중량비로 혼합한 것을 사용하며, 또한, 혼합용액의 온도는 30~70oC 이어야 하며, 상기 혼합용액의 전해중합시 적용되는 전기량은 0.1~10 쿠울롱으로 하여야 본 발명에서 요구하는 피막을 얻을 수 있다.The mixed solution is a mixture of oxalic acid and aniline in a 90:10 to 70:30 weight ratio, and the temperature of the mixed solution should be 30 ~ 70 o C, the amount of electricity applied during the electrolytic polymerization of the mixed solution is 0.1 ~ Only 10 coulombs can be used to obtain the coating required by the present invention.

옥살산과 아닐린의 혼합시 옥살산의 중량비가 전체를 100으로 보았을 때 70이하이면 폴리아닐린의 피막이 너무 두껍게 입혀져 피막에 균열이 형성되어 내식성이 떨어지고, 반대로 옥살산의 중량비가 90 이상이면 옥살산염 피막이 형성되거나 폴리아닐린 피막이 너무 적게 부착되어 역시 내식성이 떨어진다. 따라서, 옥살산과 아닐린을 90:10~70:30중량비로 혼합하여 사용한다.If the weight ratio of oxalic acid is less than 70 when the oxalic acid and aniline are mixed at 100 or less, the film of polyaniline is so thickly coated that cracks are formed on the film, resulting in inferior corrosion resistance. Too little adherence and also poor corrosion resistance. Therefore, oxalic acid and aniline are used in a mixture of 90:10 to 70:30 weight ratio.

혼합용액의 온도가 30oC이하면 반응속도가 너무 느려 피막의 균일성을 기대하기 어렵고, 70oC 이상이면 용액 증발속도가 너무 커서 관리에 어려움이 있으며 또한 비경제적이다.If the temperature of the mixed solution is 30 o C or less, the reaction rate is too slow to expect the uniformity of the film, and if the temperature is above 70 o C, the solution evaporation rate is too large, making it difficult to manage and uneconomical.

본 발명에서 상기 혼합용액은 냉연강판에 전해중합법으로 적용된다. 전해중합법으로 적용함으로써 화학적인 산화중합에 비하여 표면의 고르기와 전압을 제어하기 용이하며, 중합과 동시에 치밀한 박막을 얻을 수 있다.In the present invention, the mixed solution is applied to the cold rolled steel sheet by an electrolytic polymerization method. By applying the electrolytic polymerization method, it is easier to control the leveling and voltage of the surface than the chemical oxidation polymerization, and the dense thin film can be obtained simultaneously with the polymerization.

전기량은 전류(ampere)와 시간(sec)을 곱한 것으로 C(coulomb) = A(ampere) X T(time, sec)과 같이 나타낸다. 따라서, 1쿠울롱이란 1암페어의 전류를 1초 동안 흘려 보내준 것을 의미하는 것으로 전류가 일정하면 시간이 변화하고 시간이 일정하면 전류량이 변화하여 전기량을 원하는 값으로 유지할 수 있다.The amount of electricity is multiplied by ampere and time (sec) and is expressed as C (coulomb) = A (ampere) X T (time, sec). Therefore, 1 coulon means that a current of 1 amp is sent for 1 second. If the current is constant, the time changes, and if the time is constant, the amount of current changes to maintain the amount of electricity at a desired value.

본 발명에서 전해중합시 전기량을 0.1~10 쿠울롱으로 한정한 이유는 폴리아닐린의 피막두께를 0.05~0.5mm으로 일정하게 유지하기 위해서이다. 따라서, 전기량이 0.1 쿠울롱 이하면 폴리아닐린 피막의 두께가 0.05 mm 이하로 매우 얇아 내식성이 떨어지기 때문이고, 반면 전기량이 10 쿠울롱 이상이면 폴리아닐린의 피막 두께가 0.5 mm 이상으로 두껍게 형성되고 이렇게 되면 피막에 미세한 균열이 다량 발생되어 내식성이 급격하게 떨어지기 때문이다.The reason why the amount of electricity during electrolytic polymerization is limited to 0.1 to 10 coulombs is to maintain the film thickness of polyaniline at 0.05 to 0.5 mm. Therefore, if the amount of electricity is less than 0.1 coulombic polyaniline film is very thin because the corrosion resistance is less than 0.05 mm, whereas if the amount of electricity is more than 10 coulon, the film thickness of the polyaniline is formed thicker than 0.5 mm, and then the film This is because a large amount of fine cracks are generated in the corrosion resistance, which leads to a sharp drop in corrosion resistance.

상기 전기량과 관련하여 전류밀도는 1~100mA/cm2으로 유지하는 것이 바람직하다. 짧은 시간내에 피막을 형성하기 위하여 전류밀도를 너무 올리면 피막이 조악하게 형성될 수 있고 반면 전류밀도가 너무 낮으면 시간이 오래 걸려 경제적이지 못하기 때문이다.In relation to the amount of electricity, the current density is preferably maintained at 1 to 100 mA / cm 2 . If the current density is too high to form a film in a short time, the film may be coarse. On the other hand, if the current density is too low, it takes a long time and is not economical.

상기 각 범위를 나타내는 수치는 포함되는 것이다.Numerical values representing the above ranges are included.

이하, 본 발명을 실시예를 통하여 보다 상세하게 설명한다.Hereinafter, the present invention will be described in more detail with reference to Examples.

실시예Example

냉연강판을 10mmX20mm로 절단한 후 비코팅면은 절연물질로 피복하였다. 한편, 옥살산과 아닐린을 중량비 80:20으로 혼합하고 가열장치를 이용하여 온도를 50oC로 유지하면서 아래와 같은 조건으로 냉연강판에 정전위 전해중합하여 냉연간판에 전도성 폴리아닐린 피막을 형성하였다.After the cold rolled steel sheet was cut to 10 mm × 20 mm, the uncoated surface was coated with an insulating material. Meanwhile, oxalic acid and aniline were mixed in a weight ratio of 80:20, and a conductive polyaniline film was formed on the cold rolled sheet by electrostatic potential electropolymerization on the cold rolled sheet under the following conditions while maintaining the temperature at 50 ° C. using a heating apparatus.

정전위 전해 조건Electrostatic potential electrolytic conditions

(1) 음극 : 0.7mm두께의 냉연강판 (10mm x 20mm)(1) Cathode: 0.7mm thick cold rolled steel sheet (10mm x 20mm)

(2) 양극 : 백금판 (10mm x 20mm)(2) Anode: Platinum Plate (10mm x 20mm)

(3) 전류밀도 : 10mA/cm2 (3) Current Density: 10mA / cm 2

(4) 전기량 : 0.06 ~ 12 쿠울롱(4) Electricity: 0.06 ~ 12 Coulomb

(5) 전해조 : 음극실과 양극실이 유리필터로 분리된 500ml용량의 유리 전해조(5) Electrolyzer: 500ml glass electrolytic cell with cathode and anode chamber separated by glass filter

내식성은 Potentio/Galvanostat 273A와 은-염화은(Ag/AgCl) 참조전극을 사용하여 염화나트륨 3% 용액에서 동전위 모드로 부식전위를 측정하였다. 전기량 변화에 따른 부식전위를 하기 표 1 및 도 1에 나타내었다.Corrosion resistance was measured by the Potentio / Galvanostat 273A and the silver-silver chloride (Ag / AgCl) reference electrode in the anticorrosive mode in the sodium chloride 3% solution. Corrosion potential according to the change in electric charge is shown in Table 1 and FIG.

폴리아닐린 피막의 두께는 시편을 구리분말을 이용하여 몰딩하고 단면을 주사전자현미경으로 관찰하여 측정하였다. 각 피막의 두께를 하기 표 1에 나타내었다.The thickness of the polyaniline film was measured by molding the specimen using copper powder and observing the cross section by scanning electron microscope. The thickness of each film is shown in Table 1 below.

또한, 냉연강판에 약간의 흠집을 내고 24시간 동안 염수분무 테스트를 실시한 후의 표면상태의 광학현미경(배율 50) 사진을 도 2a 및 2b에 나타내었다. 도 2a는 종래예 1의 강판에 대한 그리고 도 2b는 발명예 1의 전도성 폴리아닐린 피막층이 형성된 냉연강판의 표면사진이다.In addition, photographs of the optical microscope (magnification 50) of the surface state after making a small scratch on the cold rolled steel sheet and performing a salt spray test for 24 hours are shown in FIGS. 2A and 2B. FIG. 2A is a surface photograph of a cold rolled steel sheet having a conductive polyaniline coating layer of Inventive Example 1, and FIG. 2B.

[표 1]TABLE 1

구분division 전기량(쿠울롱)Electricity (Kulon) 폴리아닐린 피막 두께(마이크론)Polyaniline Film Thickness (microns) 부식전위(mV)Corrosion potential (mV) 종래예 1Conventional Example 1 -- 00 -1000-1000 비교예 1Comparative Example 1 0.060.06 0.020.02 -810-810 비교예 2Comparative Example 2 1212 0.580.58 -700-700 발명예 1Inventive Example 1 0.10.1 0.050.05 -600-600 발명예 2Inventive Example 2 0.50.5 0.110.11 -500-500 발명예 3Inventive Example 3 1One 0.20.2 -400-400 발명예 4Inventive Example 4 22 0.250.25 -320-320 발명예 5Inventive Example 5 55 0.360.36 -250-250 발명예 6Inventive Example 6 88 0.450.45 -180-180 발명예 7Inventive Example 7 1010 0.50.5 -150-150

전도성 폴리아닐린 고분자 피막이 없는 종래예 1의 경우는 부식전위가 -1000mV로 상당히 큰 값을 나타냄으로 도 2a에서와 같이 염수분무 24시간 후에 현저하게 부식되었다.In the case of the prior art example 1 without the conductive polyaniline polymer film, the corrosion potential was considerably large as -1000 mV, which was significantly corroded after 24 hours of salt spray as in FIG. 2A.

비교예 1 및 2의 경우는 전기량이 본 발명에서 제시한 0.1 쿠울롱 이하이거나 10 쿠울롱 이상인 경우로 0.06 쿠울롱이면 폴리아닐린 피막이 너무 얇기 때문에 부식전위가 -810mV를 나타내고, 반대로 전기량이 12 쿠울롱인 경우는 피막 두께는 0.58 ㎛으로 상당히 두꺼우나 피막의 표면에 미세한 균열이 다량 존재하여 부식전위가 -700mV를 나타냈는데 이는 오히려 피막이 0.05 ㎛으로 아주 얇은 경우 보다 100mV 낮은 값을 나타내기 때문에 부식이 더 잘 일어날 수 있는 상태이다.In the case of Comparative Examples 1 and 2, when the amount of electricity is less than 0.1 coulombic or 10 coulon presented in the present invention, and 0.06 coulombic, the polyaniline film is too thin, and the corrosion potential is -810 mV. In this case, the film thickness is quite thick, 0.58 μm, but the corrosion potential is -700mV due to the presence of a large number of fine cracks on the surface of the film. This can happen.

발명예 1~7의 경우 가장 적은 0.1 쿠울롱의 전기량으로 전해하였을 경우의 부식전위는 종래예 1에 비하여 약 400mV 증대하였고, 전기량 10 쿠울롱으로 전해한 경우에는 종래예 1에 비하여 부식전위가 약 850mV 증대하여 내식성이 크게 향상되었다. 또한, 본 발명의 전도성 폴리아닐린 피막을 갖는 냉연강판(발명예 1)은 도 2b에서와 같이 금속표면이 부식되지 않는 양호한 상태를 유지하였다.In the case of Inventive Examples 1-7, the corrosion potential when electrolyzed with the least amount of electric power of coulombs was increased by about 400 mV compared with the prior art example 1, and when the electrolysis was carried out with the electric quantity of 10 coulombs, the corrosion potential was lower than that of the prior art example 1. 850mV increase, the corrosion resistance is greatly improved. In addition, the cold rolled steel sheet (Invention Example 1) having the conductive polyaniline coating of the present invention maintained a good state in which the metal surface was not corroded as in FIG. 2B.

본 발명에 의한 방법으로 냉연강판에 전도성 폴리아닐린 박막을 형성함으로써 우수한 내식성을 나타낸다. 본 발명의 방법은 또한 친환경적인 것이다.By forming the conductive polyaniline thin film on the cold rolled steel sheet by the method according to the present invention exhibits excellent corrosion resistance. The method of the invention is also environmentally friendly.

Claims (3)

옥산살과 아닐린이 90:10~70:30 중량비로 혼합된 30~70oC의 용액을 0.1~10 쿠울롱의 전기량으로 전해중합하여 냉연강판상에 전도성 폴리아닐린 고분자피막을 형성하는 냉연강판의 후처리 방법.After the cold rolled steel sheet electrolytically polymerized a solution of 30-70 o C mixed with oxalate and aniline in a weight ratio of 90:10 to 70:30 at an electric quantity of 0.1 to 10 coulombs to form a conductive polyaniline polymer film on the cold rolled steel sheet. Treatment method. 제 1항에 있어서, 상기 피막은 두께가 0.05~0.5mm임을 특징으로 하는 방법.The method of claim 1, wherein the coating has a thickness of 0.05 ~ 0.5mm. 제 1항에 있어서, 상기 전기분해시 전류밀도는 1~100mA/cm2임을 특징으로 하는 방법.The method of claim 1, wherein the current density during electrolysis is 1 to 100mA / cm 2 .
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100609630B1 (en) * 2004-05-17 2006-08-08 윤정모 The method of rustless surface treatment from the by-product of molybdate content conduction a macromolecule
KR100877921B1 (en) * 2007-05-30 2009-01-12 현대하이스코 주식회사 Manufacturing process of galvalume surface treated steel sheet using electrochemical polymerization of conducting polymer

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6296525A (en) * 1985-10-23 1987-05-06 Fujikura Ltd Preparation of thin-film polyaniline
JPH0372097A (en) * 1989-08-11 1991-03-27 Omron Corp Polyaniline film or its derivative film, production thereof and electrochemical device using the same
KR20010036917A (en) * 1999-10-12 2001-05-07 이구택 Surface treatment steel sheets for automobile outer panels and method for coating polymer compound thereon
KR20020047583A (en) * 2000-12-13 2002-06-22 이구택 method of manufacturing Zn electordeposited steel sheet with good corrosion resistance and surface roughness

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6296525A (en) * 1985-10-23 1987-05-06 Fujikura Ltd Preparation of thin-film polyaniline
JPH0372097A (en) * 1989-08-11 1991-03-27 Omron Corp Polyaniline film or its derivative film, production thereof and electrochemical device using the same
KR20010036917A (en) * 1999-10-12 2001-05-07 이구택 Surface treatment steel sheets for automobile outer panels and method for coating polymer compound thereon
KR20020047583A (en) * 2000-12-13 2002-06-22 이구택 method of manufacturing Zn electordeposited steel sheet with good corrosion resistance and surface roughness

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100609630B1 (en) * 2004-05-17 2006-08-08 윤정모 The method of rustless surface treatment from the by-product of molybdate content conduction a macromolecule
KR100877921B1 (en) * 2007-05-30 2009-01-12 현대하이스코 주식회사 Manufacturing process of galvalume surface treated steel sheet using electrochemical polymerization of conducting polymer

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