KR19990053139A - Electrolytic chromate treatment method of galvanized steel sheet excellent in whiteness - Google Patents
Electrolytic chromate treatment method of galvanized steel sheet excellent in whiteness Download PDFInfo
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Abstract
본 발명은 아연계 도금강판 표면에 전해크로메이트 처리를 실시하는데 있어서, 크로메이트 용액중에 3∼50g/l의 전크롬(6가크롬+3가크롬), 0.1∼5g/l의 질산 및 0.05∼0.5g/l의 붕산으로 조정되고, 그 pH가 1∼5, 온도가 20∼60℃인 용액을 사용하여, 1∼40 A/dm2의 전류밀도로서 아연계 도금강판상에 전해크로메이트 처리를 실시하는 것을 특징으로 하는 백색도가 우수한 아연도금강판의 전해크로메이트 처리방법을 요지로 한다.In the electrolytic chromate treatment of the zinc plated steel sheet, the chromate solution contains 3 to 50 g / l of total chromium (hexavalent chromium +3 trivalent chromium), 0.1 to 5 g / l of nitric acid and 0.05 to 0.5 g / l boric acid, and the electrolytic chromate treatment is carried out on the zinc-plated steel sheet at a current density of 1 to 40 A / dm 2 using a solution having a pH of 1 to 5 and a temperature of 20 to 60 ° C Which is excellent in whiteness.
Description
본 발명은 아연계 도금강판의 전해크로메이트 처리방법에 관한 것으로서, 더욱 상세히는 전해크로메이트 용액중의 성분 및 함량을 조절하고 전해조건을 조절하므로서, 크롬부착효율이 우수하여 내식성이 향상되고, 용액에 침전물도 발생하지 않으므로서 백색도가 우수한 아연계 도금강판의 전해크로메이트 처리방법에 관한 것이다.More particularly, the present invention relates to a method for treating electrolytic chromate in a zinc-based plated steel sheet, and more particularly, to an electrolytic chromate treatment method for electrolytic chromate treatment, The present invention relates to a method for electrolytic chromate treatment of a zinc plated steel sheet excellent in whiteness.
일반적으로 아연도금강판은 일반 철판에 비해 우수한 내식성을 갖고 있어서 자동차 차제, 가전제품 및 건자재 등에 널리 사용되고 있으나, 최근에 자동차업계에서는 차체 경량화에 따라 강판두께가 얇아지는 추세에 있기 때문에 이에 대비하여 강판의 고 내식성이 요구되고 있으며, 가전제품 업계에서는 가전제품의 원가절감을 위하여 가전제품에 사용되는 강판을 무도장 상태로 사용하는 경우도 많아 내식성이 우수하고 표면색상이 밝은 아연계 도금강판의 개발이 요구되고 있다. 따라서 이러한 요구에 부응하기 위하여 최근에는 아연계 도금강판에 크로메이트처리를 실시하여 내식성을 향상시킨 크로메이트 처리강판이 널리 사용되고 있다.Generally, zinc-coated steel sheets have excellent corrosion resistance compared with general steel sheets, and thus they are widely used in automobile parts, home appliances, and building materials. However, in the automobile industry, since the thickness of the steel sheet is becoming thinner due to the weight reduction of the vehicle body, In the household appliance industry, in order to reduce the cost of household appliances, many steel sheets used in home appliances are used in unpainted condition, so that the development of zinc plated steel sheet having excellent corrosion resistance and bright surface color is required have. Therefore, in order to meet such a demand, a chromate-treated steel sheet having improved corrosion resistance has recently been widely used by subjecting a zinc-plated steel sheet to a chromate treatment.
아연도금강판을 크로메이트 처리하는 방법은 크게 전해형, 반응형, 및 도포형 크로메이트 처리법으로 나뉘어진다.The method of chromating the galvanized steel sheet can be roughly classified into an electrolytic type, a reactive type, and a coating type chromate treatment method.
반응형 크로메이트 처리법의 경우 반응조내에 용액을 체우고 그 내부로 강판을 통과시키거나, 용액을 강판에 직접 분사하여 강판과 크로메이트 용액과 반응에 의해 피막이 형성되는 방법으로서, 크로메이트 피막생성은 처리하고자 하는 도금강판의 표면특성, 강판의 진행속도 등에 크게 좌우되기 때문에 백색도는 높지만 일정한 색상을 얻기가 힘들다. 도포형 크로메이트 처리법의 경우에는 롤에 크로메이트 용액을 묻혀서 강판에 전사시킨후 건조시켜 크로메이트 파막을 형성시키는 방법으로, 표면 백색도는 비교적 높고 일정하지만, 크롬피막의 부착량이 용액의 점도에 영향을 받기 때문에 다양한 크롬부착량의 강판을 생산하기 위해서는 그 때마다 크로메이트 처리용액을 바꿔야 하므로 용액관리가 번잡하다는 문제점이 있다. 또 하나의 전해형 크로메이트 처리법의 경우 강판을 음극으로 하여 크로메이트 용액이 체워진 전해조 내로 통과시키면서 통전시켜 강판에 크로메이트 피막을 형성시키는 방법으로서, 피막부착량의 조절이 통전량의 조절에 의해서 가능하므로 하나의 크로메이트 용액에서 다양한 크롬부착량의 크로메이트 강판을 제조할 수 있다.In the case of the reactive chromate treatment method, a coating is formed by reacting a steel sheet with a chromate solution by sieving a solution into a reaction vessel and passing the steel sheet through the steel sheet or spraying the solution directly onto a steel sheet, It is difficult to obtain a uniform color although the whiteness is high because it depends on the surface characteristics of the steel sheet and the progress speed of the steel sheet. In the case of the coating type chromate treatment method, the chromate film is formed by transferring a chromate solution to a roll after being transferred to a steel sheet, followed by drying to obtain a chromate film. Although the surface whiteness is relatively high and constant, the deposition amount of the chromium film is influenced by the viscosity of the solution. In order to produce a chromium-adhered steel sheet, it is necessary to change the chromate treatment solution every time, so that the solution management is troublesome. Another electrolytic type chromate treatment method is a method of forming a chromate film on a steel sheet by passing a chromate solution through an electrolytic bath in which a steel plate is used as a negative electrode and passing through the electrolytic bath to control the coating amount of the film by controlling the amount of electricity, A chromate steel sheet having various chromium adhesion amounts can be produced in a chromate solution.
종래의 전해크로메이트 처리용액중에는 크로메이트 피막형성 촉진제로서, SO4 2-나 Cl-등을 첨가하였다. 그러나 SO4 2-를 첨가한 경우에는 크로메이트 처리후에 강판표면의 백색도가 낮아 색상이 어두운 단점이 있으며, 이는 SO4 2-농도가 증가할수록 더 어두워진다. 이에 대한 원인은 크로메이트 피막중에 SO4 2-가 공석되어 색상이 어두워지는 것으로 판단되지만 아직까지 정확하게 밝혀지지 않았다. 또한 피막형성 촉진제로서 Cl-을 첨가한 경우에는 황색을 띄며, 첨가량이 증가하면 얼룩이 발생하는 문제점과 함께 크로메이트 용액을 혼탁하게 하는 단점이 있다. 따라서 종래의 방법으로 제조된 전해크로메이트 강판의 경우에는 무도장 상태로 사용하지 못하고 주로 도장용으로 사용되고 있었다.In the conventional electrolytic chromate treatment solution, SO 4 2- , Cl - or the like was added as a chromate film formation accelerator. However, when SO 4 2- is added, the whiteness of the surface of the steel sheet after the chromate treatment is low and there is a dark color defect, which becomes darker as the SO 4 2- concentration increases. The reason for this is believed to be the darkening of the chromate film due to the release of SO 4 2- , but it has not been clarified yet. In addition, when Cl - is added as a film formation accelerator, it is yellowish. When the amount of Cl - added is increased, unevenness is generated and chromate solution becomes turbid. Therefore, the electrolytic chromate steel sheet manufactured by the conventional method can not be used in a non-coated state, and is mainly used for coating.
따라서 본 발명자는 상술한 문제점을 해결하기 위하여, 아연계 크로메이트 강판을 전해처리에 의해서 제조하는데 있어서, 강판의 백색도가 낮은 문제점을 해결하기 위한 연구와 실험을 행한 결과, 크로메이트 용액중에 피막촉진제의 종류와 함량을 조정하면서 상기의 문제점의 해결이 가능하다는데 착안하여 본 발명을 제안하게 되었다. 즉, 본 발명은 크로메이트 용액중에 소량의 붕산과 질산을 첨가하여 백색도가 높으면서 내식성이 우수한 전해크로메이트 처리 강판을 안정적으로 제조할 수 있는 방법을 제공하는 데 그 목적이 있다.Therefore, the inventors of the present invention have conducted studies and experiments to solve the problem of low whiteness of the steel sheet in manufacturing zinc-based chromate steel sheets by electrolytic treatment in order to solve the above-mentioned problems. As a result, It is possible to solve the above-mentioned problems while adjusting the content. That is, an object of the present invention is to provide a method for stably producing an electrolytically chromate-treated steel sheet having high whiteness and excellent corrosion resistance by adding a small amount of boric acid and nitric acid to a chromate solution.
상술한 목적을 달성하기 위한 본 발명은 아연계 도금강판 표면에 전해크로메이트 처리를 실시하는데 있어서, 크로메이트 용액중에 3∼50g/l의 전크롬(6가크롬+3가크롬), 0.1∼5g/l의 질산 및 0.05∼0.5g/l의 붕산으로 조정되고, 그 pH가 0.5∼5, 온도가 20∼60℃인 용액을 사용하여, 1∼40 A/dm2의 전류밀도로서 아연계 도금강판상에 전해크로메이트 처리를 실시하는 것을 특징으로 하는 백색도가 우수한 아연도금강판의 전해크로메이트 처리방법을 제공하는 것을 특징으로 한다.In order to accomplish the above object, the present invention provides a method for producing a zinc-based plated steel sheet, which comprises applying an electrolytic chromate treatment to the surface of a zinc-based plated steel sheet in an amount of 3 to 50 g / l of total chromium (hexavalent chromium +3 trivalent chromium) Nitric acid and 0.05 to 0.5 g / l of boric acid at a current density of 1 to 40 A / dm < 2 > using a solution having a pH of 0.5 to 5 and a temperature of 20 to 60 DEG C, Which is characterized by providing an electrolytic chromate treatment on the zinc-plated steel sheet having excellent whiteness.
이하 본 발명에 대하여 상세히 설명하면 다음과 같다.Hereinafter, the present invention will be described in detail.
본 발명은 아연계 도금강판 표면에 크로메이트 처리를 실시하는데 있어서, 크로메이트 용액중에 3∼50g/l의 전크롬(6가크롬+3가크롬), 0.1∼5g/l의 질산 및 0.05∼0.5g/l의 붕산으로 조정되고, 그 pH가 0.5∼5, 온도가 20∼60℃인 용액을 사용하여, 1∼40A/dm2의 전류밀도로서 아연계 도금강판상에 전해크로메이트 처리를 실시하므로서 백색도가 높고, 내식성이 우수한 전해크로메이트처리 강판을 안정적으로 제조할 수 있는 백색도가 높은 아연 도금강판의 전해크로메이트 처리방법에 관한 것이다.In the chromate treatment of the zinc plated steel sheet, the chromate solution contains 3 to 50 g / l of total chromium (hexavalent chrome +3 plus chromium), 0.1 to 5 g / l of nitric acid, and 0.05 to 0.5 g / and the electrolytic chromate treatment is carried out on the zinc-plated steel sheet at a current density of 1 to 40 A / dm 2 using a solution having a pH of 0.5 to 5 and a temperature of 20 to 60 ° C, The present invention relates to a method for electrolytic chromate treatment of a galvanized steel sheet having a high degree of whiteness and capable of stably producing an electrolytically-chromate-treated steel sheet having high corrosion resistance.
이하, 본 발명에 있어서 전해크로메이트 용액조성 및 전해조건을 상기와 같이 제한한 이유에 대하여 상세히 설명한다.Hereinafter, the reason why electrolytic chromate solution composition and electrolysis conditions are limited as described above will be described in detail in the present invention.
아연계 도금강판 표면에 크로메이트 처리를 실시하는데 있어서, 크로메이트 용액중 6가 크롬은 무수크롬산, 중크롬산염, 크롬산등을 1종 혹은 2종 이상을 혼합하여 첨가되며, 3가 크롬은 전해작업시 음극에서 6가 크롬이 환원되어 3가크롬으로 존재한다. 크로메이트 용액중 6가 크롬과 3가 크롬의 합계치인 전 크롬농도가 3g/l 이하가 되면 음극에서 수소발생반응이 극심하여 크로메이트 피막색상이 검게되고 또한 크로메이트 피막 전착효율이 낮기 때문에 생산성이 떨어지며, 또한 전크롬 농도가 50g/l를 초과하더라도 피막전착효율은 거의 일정하기 때문에 경제적이지 못하므로 크로메이트 용액중 전 크롬농도는 3∼50g/l로 한정하는 것이 바람직하다.In carrying out the chromate treatment on the surface of the zinc plated steel sheet, the hexavalent chromium in the chromate solution is added in an admixture of one or more kinds of chromic acid anhydride, dichromate, and chromic acid, and the trivalent chromium Hexavalent chromium is reduced to exist as trivalent chromium. When the total chromium concentration, which is the sum of the hexavalent chromium and the trivalent chromium in the chromate solution, is 3 g / l or less, the hydrogen generation reaction becomes extremely severe in the cathode, resulting in a black chromate film color and low productivity of the chromate film electrodeposition. Even if the total chromium concentration exceeds 50 g / l, the coating electrodeposition efficiency is almost constant and is not economical, so that the total chromium concentration in the chromate solution is preferably limited to 3 to 50 g / l.
크로메이트 용액중 붕산은 크로메이트 피막형성반응을 촉진시켜주는 역할을 주로 하고 질산은 표면색상을 밝게 하는 것으로서, 용액중에 붕산이 0.05g/l 이하가 되면 크로메이트 피막형성효율이 감소하기 때문에 전력비가 증가하여 경제적이지 못하여 0.5g/l을 초과하면 적출된 크로메이트 피막을 재 용해시키기 때문에 크로메이트 피막부착성이 떨어지는 문제점이 있으므로 붕산의 농도는 0.05∼0.5g/l로 제한함이 바람직하다.Boric acid in the chromate solution mainly serves to accelerate the formation of the chromate film and brightens the surface color of silver nitrate. When the boric acid is less than 0.05 g / l in the solution, the chromate film formation efficiency decreases, And if it exceeds 0.5 g / l, there is a problem that the separated chromate film is re-dissolve and the adhesion of the chromate film is deteriorated. Therefore, the concentration of boric acid is preferably limited to 0.05 to 0.5 g / l.
또한 질산은 크로메이트 강판의 피막을 밝게 해주는 역할을 하는 첨가제로서, 그 자체만으로서는 피막형성을 촉진시켜주는 역할을 하지 못하기 때문에 반드시 붕산이 함께 첨가되어야만 한다. 붕산과 함께 첨가될때에도 질산의 첨가량이 0.1g/l 이하가 되면 백색도 향상효과가 거의 미약하고, 5g/l을 초과하면 용액에 침전물을 발생시키기 때문에 질산의 첨가량은 0.1∼5g/l로 제한하는 것이 바람직하다.In addition, nitric acid is an additive which brightens the coating of the chromate-coated steel sheet, and since it does not play a role of promoting the film formation by itself, boric acid must be added together. Even when added together with boric acid, the whiteness improvement effect is insignificant when the added amount of nitric acid is less than 0.1 g / l, and when the added amount exceeds 5 g / l, the precipitate is generated in the solution, so the added amount of nitric acid is limited to 0.1 to 5 g / .
전해크로메이트 용액의 pH가 0.5이하가 되면 전해처리시 도금강판 표면에 생성된 크로메이트 피막이 재 용해되어 피막 부착효율이 떨어지기 때문에 비경제적이며, pH가 5를 초과하면 3가 크롬이 용액중에서 수산화크롬으로 침전하기 때문에 작업성이 떨어지므로 용액의 pH는 0.5∼5로 제한함이 바람직하다.When the pH of the electrolytic chromate solution is less than 0.5, the chromate film formed on the surface of the coated steel sheet is re-dissolved during the electrolytic treatment and the coating adhesion efficiency is lowered. Thus, when the pH exceeds 5, trivalent chromium It is preferable to limit the pH of the solution to 0.5 to 5 since the workability is deteriorated due to sedimentation.
전해크로메이트 온도가 20℃ 이하가 되면 크로메이트 피막석출 효율이 떨어지고 60℃를 초과하면 용액의 증발량이 많아져 농도가 변하므로 전해온도는 20∼60℃가 적당하다.When the electrolytic chromate temperature is lower than 20 ° C, the chromate film deposition efficiency is lowered. When the electrolytic chromate temperature is higher than 60 ° C, the evaporation amount of the solution is increased and the concentration is changed. Therefore, the electrolytic temperature is preferably 20 to 60 ° C.
상술한 전해액을 사용하여 전해처리를 실시할 때 전류밀도 1A/dm2이하에서는 크로메이트 피막부착속도가 느리기 때문에 필요한 크롬부착량을 확보하는데 시간이 많이 걸려 경제적이지 못하며, 전류밀도가 40 A/dm2을 초과하면 크롬수산화물이 주성분인 크로메이트 피막을 형성하지 않고 금속크롬으로 전착되는 비율이 증가하기 때문에 크롬전착효율이 감소하므로 전해크로메이트 처리시 전류밀도는 1∼40A/dm2으로 제한함이 바람직하다.When electrolytic treatment using the above-mentioned electrolytic solution is performed, when the current density is less than 1 A / dm 2 , the rate of deposition of the chromate film is slow. Therefore, it takes a long time to secure the required amount of chromium and the current density is not less than 40 A / dm 2 It is preferable that the current density is limited to 1 to 40 A / dm 2 when the electrolytic chromate treatment is performed, because the chromium electrodeposition efficiency is reduced because the rate of electrodeposition with metal chromium increases without forming a chromate film which is the main component of chromium hydroxide.
이하 실시예를 통하여 본 발명을 상세히 설명한다.Hereinafter, the present invention will be described in detail with reference to examples.
하기의 표 1과 같은 조성를 갖도록 크로메이트 용액을 제조하여, 20 g/m2의 아연도금강판을 사용하여 하기의 표 1의 전해조건으로 전해크로메이트를 실시하여 그 결과를 표 2에 나타내었다. 전해처리시간은 전기량 20 C/dm2이 되도록 각 전류밀도별로 다르게 조정하였다.A chromate solution was prepared so as to have the composition shown in the following Table 1, and electrolytic chromate was performed under the electrolytic condition of the following Table 1 using a zinc plated steel sheet of 20 g / m 2 , and the results are shown in Table 2. The electrolytic treatment time was adjusted differently for each current density so that the electricity quantity was 20 C / dm 2 .
상기 표 2의 백색도는 색차계를 사용하여 측정하였으며, 내식성 평가는 JIS-Z-2371에 규정된 염수분무시험을 실시하여 강판표면에 발생한 백청면적을 측정하여 나타내었다.The whiteness shown in Table 2 was measured using a colorimeter. The corrosion resistance was evaluated by measuring the area of the white rust on the surface of the steel sheet subjected to the salt spray test prescribed in JIS-Z-2371.
점전물발생정도는 크로메이트용액을 제조하여 3.6 × 105C/dm2의 전기량을 통전시킨후 용액중에 존재하는 침전물 발생정도를 육안관찰하였다.The chromate solution was prepared and the electric charge of 3.6 × 10 5 C / dm 2 was energized and the degree of occurrence of precipitates present in the solution was visually observed.
상기 표 1에 나타낸 바와 같이 본 발명에 부합되는 발명에(1∼7)에서와 같이 전 크롬농도를 3∼50g/l, 0.1∼5g/l의 질산 및 0.05∼0.5g/l의 붕산으로 조정되고, 그 pH가 0.5∼5, 온도가 20∼60℃인 용액을 사용하여, 1∼40 A/dm2의 전류밀도로서 아연계 도금강판상에 전해크로메이트를 실시한 경우 상기 표 2의 발명예(1-7)에 나타난 바와 같이 크롬부착효율이 13% 이상이고 백청발생면적이 10%이하로 내식성이 우수하였으며, 3.6×105C/dm2의 전기량을 통전시킨후 용액중에 침전물이 발생하지 않았으며, 강판의 백색도가 80이상으로 우수하였다. 그러나 비교예(1) 및 (2)에서와 같이 전크롬농도, pH, 온도 및 전류밀도는 본 발명에 부합되지만, 첨가제로서 황산을 첨가한 경우에는 크롬부착효율은 14.7% 이상으로 우수하고 백청발생도 10%이하 이지만 강판의 백색도가 73.5 로 낮아서 색상이 어두워졌다.As shown in the above Table 1, the total chromium concentration is adjusted to 3 to 50 g / l, 0.1 to 5 g / l of nitric acid and 0.05 to 0.5 g / l of boric acid as in the inventions (1 to 7) And electrolytic chromate was applied on the zinc plated steel sheet at a current density of 1 to 40 A / dm 2 using a solution having a pH of 0.5 to 5 and a temperature of 20 to 60 ° C. 1-7), the chromium deposition efficiency was 13% or more and the area of occurrence of white rust was 10% or less, which was excellent in corrosion resistance. No electric charge of 3.6 × 10 5 C / dm 2 was applied and no precipitate was formed in the solution And the whiteness of the steel sheet was 80 or more. However, as in Comparative Examples (1) and (2), the chromium concentration, pH, temperature, and current density were in accordance with the present invention, but when sulfuric acid was added as an additive, the chromium deposition efficiency was excellent at 14.7% But the whiteness of the steel sheet was as low as 73.5, and the color became dark.
비교예(3,4)의 경우는 첨가체로서 염산을 0.1g/l 첨가한 경우로서 크롬부착효율이 15.6%로 높고 백청발생면적이 5%로서 내식성도 우수하고 용액에 침전물도 발생하지 않지만 강판의 백색도가 75.4로 낮다.In the case of Comparative Example (3, 4), 0.1 g / l of hydrochloric acid was added as an additive, and the chromium deposition efficiency was as high as 15.6% and the area of the white rust was 5%, which was excellent in corrosion resistance, Whiteness is as low as 75.4.
비교예(4)의 경우에는 염산을 1g/l 첨가한 경우로서, 크롭부착효율이 높고 내식성이 우수하고 용액에 침전물을 발생시키지 않지만 강판의 백색도가 73.4로 비교적 낮다.In the case of Comparative Example (4), when 1 g / l of hydrochloric acid was added, the crop adhesion efficiency was high and the corrosion resistance was excellent and the precipitate was not generated in the solution, but the whiteness of the steel sheet was relatively low as 73.4.
비교예 (6)의 경우에는 질산의 첨가량이 본 발명에서 한정한 범위보다 많게 첨가된 경우로서 크롬부착효율 및 내식성이 우수하고 백색도도 84.3으로 높지만, 용액에 침전물을 형성하였다.In the case of the comparative example (6), in the case where the added amount of nitric acid was more than the range defined in the present invention, the chromium adhesion efficiency and corrosion resistance were excellent and the whiteness degree was as high as 84.3, but a precipitate was formed in the solution.
비교예(7)의 경우에는 질산만을 1.2g/l첨가한 경우로서, 백색도가 84.7로 높고 침전물발생이 없으나 크롬부착효율이 4.3% 로 낮기 때문에 강판의 백청발생면적이 90%로 높았다.In the case of Comparative Example (7), only 1.2 g / l of nitric acid was added. The whiteness of the steel sheet was as high as 90% because the whiteness was as high as 84.7 and no precipitate was formed but the chromium deposition efficiency was as low as 4.3%.
비교예(8)의 경우에는 붕산첨가량이 본 발명에서 제한한 범위를 벋어난 경우로서, 백색도가 84.7로 높고 침전물 발생이 없으나 크롬부착효율이 7.3%로 낮기 때문에 강판의 백청발생면적이 60%로 높았다.In the case of the comparative example (8), when the amount of boric acid added is less than the range limited by the present invention, whiteness is as high as 84.7 and no precipitate is generated, but the chromium deposition efficiency is as low as 7.3% Respectively.
비교예(9),(10)은 전류밀도와 온도가 본발명에서 제한한 범위를 벗어난 경우로서 크롬부착효율이 7.5%이하이고 이로 인해 백청발생면적이 60%이상 되었다.In Comparative Examples (9) and (10), when the current density and temperature were out of the range defined in the present invention, the chromium deposition efficiency was 7.5% or less, which resulted in the occurrence area of the white rust being 60% or more.
상술한 바와 같이 본 발명은 전해크로메이트 용액중의 성분 및 함량을 조절하고 전해조건을 조절하므로서, 크롬부착효율이 우수하여 내식성이 향상되고, 용액에 침전물도 발생하지 않으면서, 강판표면의 백색도가 높은 전해크로메이트강판을 제조할수 있는 우수한 효과가 있다.As described above, according to the present invention, the chromium-attaching efficiency is improved and the corrosion resistance is improved by controlling the components and the content in the electrolytic chromate solution and by adjusting the electrolysis conditions, and the whiteness An electrolytic chromate steel sheet can be produced.
Claims (1)
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| KR1019970072730A KR100321618B1 (en) | 1997-12-23 | 1997-12-23 | Electrolytic chromate treatment of galvanized steel sheet with high whiteness degree and excellent corrosion resistance |
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| KR100858711B1 (en) * | 2007-03-30 | 2008-09-17 | 한국기계연구원 | Trivalent chromium galvanizing solution |
| US11019548B2 (en) | 2017-11-24 | 2021-05-25 | Samsung Electronics Co., Ltd. | Electronic device and communication method thereof |
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| KR100858711B1 (en) * | 2007-03-30 | 2008-09-17 | 한국기계연구원 | Trivalent chromium galvanizing solution |
| US11019548B2 (en) | 2017-11-24 | 2021-05-25 | Samsung Electronics Co., Ltd. | Electronic device and communication method thereof |
| US11218938B2 (en) | 2017-11-24 | 2022-01-04 | Samsung Electronics Co., Ltd. | Electronic device and communication method thereof |
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