JPH062193A - Manufacture of electrogalvanized steel plate excelling in surface appearance - Google Patents
Manufacture of electrogalvanized steel plate excelling in surface appearanceInfo
- Publication number
- JPH062193A JPH062193A JP18634392A JP18634392A JPH062193A JP H062193 A JPH062193 A JP H062193A JP 18634392 A JP18634392 A JP 18634392A JP 18634392 A JP18634392 A JP 18634392A JP H062193 A JPH062193 A JP H062193A
- Authority
- JP
- Japan
- Prior art keywords
- bath
- electrogalvanizing
- plating
- steel sheet
- electrogalvanized
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Landscapes
- Electroplating And Plating Baths Therefor (AREA)
- Electroplating Methods And Accessories (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】この発明は、高電流密度によっ
て、表面色調が白い、表面外観の優れた電気亜鉛めっき
鋼板を製造するための方法に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an electrogalvanized steel sheet having a white surface tone and an excellent surface appearance due to a high current density.
【０００２】[0002]
【従来の技術】鋼板の表面上に電気亜鉛めっき層を形成
するための方法として、主として硫酸亜鉛を含有する酸
性電気亜鉛めっき浴中において、亜鉛からなる自溶性陽
極を使用して電気亜鉛めっきする方法と、前記酸性電気
亜鉛めっき浴中において、鉛系合金や酸化イリジウムか
らなる不溶性陽極を使用して電気亜鉛めっきする方法と
がある。2. Description of the Related Art As a method for forming an electrogalvanized layer on the surface of a steel sheet, electrogalvanizing is carried out using a self-fluxing anode made of zinc in an acidic electrogalvanizing bath containing mainly zinc sulfate. And a method of electrogalvanizing in the acidic electrogalvanizing bath using an insoluble anode made of a lead-based alloy or iridium oxide.
【０００３】亜鉛からなる自溶性陽極を使用して電気亜
鉛めっきする方法には、生産性の向上のため、高電流密
度で鋼板に電気めっきする場合に、消耗した自溶性陽極
の交換を頻繁に行わなければならない問題がある。そこ
で、近年は、高電流密度で鋼板に電気亜鉛めっきする場
合には、鉛系合金や酸化イリジウムからなる不溶性陽極
を使用し、電気亜鉛めっき浴中に、めっき浴の電気抵抗
を減少させるための電導度補助剤を添加し、このような
電導度補助剤が添加されためっき浴中において、鋼板を
電気亜鉛めっきすることが行われており、例えば、特開
昭61-170595 号には、電導度補助剤として硫酸ソーダが
添加された酸性亜鉛電気めっき浴中において、鋼板を電
気亜鉛めっきする方法が開示されている。In the method of electrogalvanizing using a self-fluxing anode made of zinc, in order to improve productivity, when electroplating a steel sheet at a high current density, the exhausted self-fluxing anode is frequently replaced. There is a problem that has to be done. Therefore, in recent years, when electrogalvanizing a steel sheet with a high current density, an insoluble anode made of a lead-based alloy or iridium oxide is used to reduce the electric resistance of the plating bath during the electrogalvanizing bath. An electrical conductivity auxiliary agent is added, and a steel sheet is electrogalvanized in a plating bath to which such an electrical conductivity auxiliary agent has been added. For example, JP-A-61-170595 discloses an electrical conductivity method. There is disclosed a method of electrogalvanizing a steel sheet in an acidic zinc electroplating bath to which sodium sulfate is added as a temperature auxiliary agent.
【０００４】一方、電気亜鉛めっき鋼板は、家庭電器用
鋼板として広く使用されているが、家庭電器用鋼板の場
合には、未塗装で使用されることが多いために、めっき
層の表面外観の向上が強く要望されている。そこで、め
っき層の表面外観の向上のために、めっき浴中に各種の
光沢剤を添加し、このような光沢剤が添加されためっき
浴中において、鋼板を電気亜鉛めっきする技術が開発さ
れており、例えば、特開昭63-14890号、特公昭55-41306
号等には、光沢剤として有機物が添加された電気亜鉛め
っき浴中において鋼板を電気亜鉛めっきする方法が開示
されている。On the other hand, electrogalvanized steel sheets are widely used as steel sheets for household electric appliances. However, in the case of steel sheets for household electrical appliances, since they are often used unpainted, the surface appearance of the plating layer is There is a strong demand for improvement. Therefore, in order to improve the surface appearance of the plating layer, a technique has been developed in which various brightening agents are added to the plating bath and the steel sheet is electrogalvanized in the plating bath containing such brightening agent. For example, JP-A-63-14890, JP-B-55-41306
JP-A No. 2003-242242 discloses a method of electrogalvanizing a steel sheet in an electrogalvanizing bath to which an organic substance is added as a brightening agent.
【０００５】[0005]
【発明が解決しようとする課題】しかしながら、高電流
密度で鋼板を電気亜鉛めっきするために、電気亜鉛めっ
き浴中に電導度補助剤を添加すると、めっき浴の電気抵
抗は減少する反面、めっき浴の粘度が上昇して、陰極
（カソード）の界面における拡散層が厚くなり、許容電
流密度の低下を招くおそれがある。更に、硫酸ソーダ等
の電導度補助剤は、めっき層の表面を黒っぽくし、電気
亜鉛めっき鋼板の表面外観に対して悪影響を及ぼす場合
が多い。However, if a conductivity auxiliary agent is added to the electrogalvanizing bath for electrogalvanizing a steel sheet at a high current density, the electric resistance of the electroplating bath decreases, while the electroplating bath decreases. There is a possibility that the viscosity will increase and the diffusion layer at the interface of the cathode (cathode) will become thick, resulting in a decrease in the allowable current density. Further, a conductivity auxiliary agent such as sodium sulfate darkens the surface of the plating layer and often adversely affects the surface appearance of the electrogalvanized steel sheet.
【０００６】一方、電気亜鉛めっき鋼板の表面外観を向
上させるために、めっき浴中に、光沢剤として有機物を
添加すると、不溶性陽極、特に、近年多く使用されてい
る白金族系の酸化イリジウムからなる不溶性陽極の寿命
に悪影響を及ぼすことが知られている（例えば、第12回
ソーダ工業技術討論会(1988.11.17,18) 資料「有機電解
の対極酸素発生アノードとしての酸化イリジウム系電極
の性能向上」第１頁，第18行) 。更に、有機物の添加に
よりめっき浴の粘度が上昇して、上述したように、陰極
界面における拡散層が厚くなり、許容電流密度の低下を
招く。従って、高電流密度操業において、めっき浴中に
光沢剤を添加することには問題が多い。On the other hand, in order to improve the surface appearance of the electrogalvanized steel sheet, when an organic substance is added as a brightening agent in the plating bath, an insoluble anode, particularly platinum group-based iridium oxide, which has been widely used in recent years, is formed. It is known to have an adverse effect on the life of insoluble anodes (for example, 12th Soda Industrial Technology Conference (1988.11.17,18), Material "Improving the performance of iridium oxide based electrodes as counter electrode oxygen generating anodes for organic electrolysis". "Page 1, line 18). Further, the addition of the organic substance increases the viscosity of the plating bath, and as described above, the diffusion layer at the cathode interface becomes thick, resulting in a decrease in the allowable current density. Therefore, in high current density operations, adding brighteners to the plating bath is problematic.
【０００７】従って、この発明の目的は、上述した問題
を解決し、めっき浴中に電導度補助剤を添加することな
く、めっき浴の電気抵抗を減少させ、且つ、めっき浴中
に光沢剤を添加することなく、高電流密度で電気亜鉛め
っきしても、明度が85以上の表面色調が白い、表面外観
の優れた電気亜鉛めっき鋼板を製造し得る方法を提供す
ることにある。Therefore, an object of the present invention is to solve the above-mentioned problems, to reduce the electric resistance of a plating bath and to add a brightening agent to the plating bath without adding a conductivity auxiliary agent to the plating bath. It is an object of the present invention to provide a method capable of producing an electrogalvanized steel sheet having a brightness of 85 or more and a white surface color tone and an excellent surface appearance, even if electrogalvanized at a high current density without addition.
【０００８】[0008]
【課題を解決するための手段】本発明者らは、上述した
問題を解決すべく鋭意研究を重ねた。その結果、亜鉛イ
オンを ZnSO4・7H2O換算で400 〜600 g/l 含有する、高
温且つ高流速で低pH値の電気亜鉛めっき浴中において、
不溶性陽極を使用し、鋼板を電気亜鉛めっきすれば、電
気亜鉛めっき浴中に電導度補助剤を添加しなくても、め
っき浴の電気抵抗が減少して電導度が増加し、且つ、光
沢剤を添加しなくても、高電流密度において、明度が85
以上の表面色調が白い、表面外観の優れた電気亜鉛めっ
き鋼板を製造し得ることを知見した。[Means for Solving the Problems] The present inventors have conducted extensive studies to solve the above-mentioned problems. As a result, the zinc ion to 400 to 600 g / l containing at ZnSO 4 · 7H 2 O in terms of, in electro-galvanized bath of hot and low pH values at a high flow rate,
If an insoluble anode is used and the steel sheet is electrogalvanized, the electrical resistance of the electroplating bath will decrease and the electroconductivity will increase without adding an electroconductivity auxiliary agent to the electrogalvanizing bath. Even without the addition of
It was found that the above electrogalvanized steel sheet having a white surface color tone and an excellent surface appearance can be produced.
【０００９】この発明は、上記知見に基づいてなされた
ものであって、亜鉛イオンを ZnSO4・7H2O換算で400 〜
600 g/l 含有する、浴温:60 〜80℃、pH値: ０〜１、流
速：２m/s 以上の電気亜鉛めっき浴中において、不溶性
陽極を使用し、200 〜300 A/dm2 の電流密度により、鋼
板を電気亜鉛めっきして、前記鋼板の少なくとも１つの
表面上に、前記鋼板の片面当たり10〜100 g/m2の量の電
気亜鉛めっき層を形成することに特徴を有するものであ
る。The present invention was made on the basis of the above findings, in which zinc ions of 400 to 400 in terms of ZnSO 4 .7H 2 O are converted.
In an electrogalvanizing bath containing 600 g / l, bath temperature: 60-80 ° C, pH value: 0-1, flow rate: 2 m / s or more, using an insoluble anode, 200-300 A / dm 2 Characterized by electrogalvanizing a steel sheet by current density to form an electrogalvanized layer on at least one surface of the steel sheet in an amount of 10 to 100 g / m 2 per one side of the steel sheet. Is.
【００１０】[0010]
【作用】電気亜鉛めっき層の表面形態は、陰極（カソー
ド）界面における亜鉛イオンの移動現象に強く影響され
る。即ち、このような亜鉛イオンの移動を促進させる条
件即ち高温且つ高流速で低pH値の電気亜鉛めっき浴中に
おいて、鋼板を電気亜鉛めっきした場合には、鋼板に平
行なフラットな面（0002) を有する結晶が強く配向し、
一方、亜鉛イオンの移動が促進されない上記と逆の条件
で鋼板を電気亜鉛めっきした場合には、鋼板に数１や数
２のピラミッド状の面を有する結晶が強く配向する。The surface morphology of the electrogalvanized layer is strongly influenced by the migration phenomenon of zinc ions at the cathode (cathode) interface. That is, in the case of electrogalvanizing a steel sheet under conditions that promote the movement of such zinc ions, that is, in an electrogalvanizing bath having a high pH at a high temperature and a high flow rate, a flat surface parallel to the steel sheet (0002) Crystals with a strong orientation,
On the other hand, when the steel sheet is electrogalvanized under the condition opposite to the above in which the movement of zinc ions is not promoted, the crystals having the pyramid-shaped faces of the formulas 1 and 2 are strongly oriented.
【００１１】[0011]
【数１】 [Equation 1]
【００１２】[0012]
【数２】 [Equation 2]
【００１３】陰極の表面においては、亜鉛結晶核の発生
とその成長とが同時に生ずる。即ち、めっき電流密度が
低い場合には、結晶核が、その発生よりも優先的に成長
する結果、亜鉛結晶が粗大化する。逆に、めっき電流密
度が高い場合には、結晶核が、その成長よりも優先的に
発生する結果、亜鉛結晶が微細化する。On the surface of the cathode, zinc crystal nuclei are generated and grown at the same time. That is, when the plating current density is low, the crystal nuclei grow preferentially over their generation, resulting in coarsening of the zinc crystals. On the contrary, when the plating current density is high, the crystal nuclei are generated preferentially over the growth thereof, so that the zinc crystal is miniaturized.
【００１４】電気亜鉛めっき層の外観は、その表面形態
に依存すると考えられるが、電気亜鉛めっき層自体には
色がないので、めっき層の表面色調即ちその白さは、め
っき層表面の明度（Ｌ値）によって評価することができ
る。そして、亜鉛めっき層の結晶形態と、その明度と
は、次のような関係にある。即ち、亜鉛結晶が微細でフ
ラットな場合には、亜鉛めっき層は、光を反射しやすい
ために、その明度が高くなり表面色調が白くなる。一
方、亜鉛めっき層の結晶がピラミッド状で粗大な場合に
は、光を吸収しやすいために、その明度が低下して表面
色調が黒っぽくなる。The appearance of the electrogalvanized layer is considered to depend on its surface morphology, but since the electrogalvanized layer itself has no color, the surface tone of the electroplated layer, that is, its whiteness, is the lightness ( It can be evaluated by L value). The crystal morphology of the galvanized layer and its brightness have the following relationship. That is, when the zinc crystal is fine and flat, the zinc plating layer easily reflects light, so that the brightness is high and the surface color tone is white. On the other hand, when the crystals of the galvanized layer are pyramid-shaped and coarse, light absorption is likely to occur, resulting in a decrease in brightness and a dark surface color tone.
【００１５】上述した観点から、亜鉛イオンを ZnSO4・
7H2O換算で400 〜600 g/l 含有する電気亜鉛めっき浴中
において、不溶性陽極を使用し、鋼板を電気亜鉛めっき
した場合に、結晶が、その成長よりも優先的に発生し
て、結晶が微細化するめっき電流密度の下限を調べたと
ころ、200 A/dm2 であることがわかった。即ち、めっき
電流密度が200 A/dm2 未満では、結晶核が、その発生よ
りも優先的に成長して、結晶が粗大化し、めっき層の明
度が低下して表面色調が黒っぽくなる。一方、めっき電
流密度が300 A/dm2 を超えて大きくなると、陰極界面に
おける亜鉛イオンの濃度が０になる結果、めっき層の表
面にめっき焼けが生じやすくなる。従って、この発明に
おいて、めっき電流密度は、200 〜300 A/dm2 の範囲内
に限定すべきである。From the above-mentioned viewpoint, zinc ions are replaced by ZnSO 4 .multidot.
In electro-galvanized bath to 7H 2 O converted at containing 400 to 600 g / l, using an insoluble anode, when electric galvanized steel sheets, crystal, preferentially occur than its growth, crystal When the lower limit of the plating current density at which the grain size was reduced was investigated, it was found to be 200 A / dm 2 . That is, when the plating current density is less than 200 A / dm 2 , the crystal nuclei grow preferentially over the generation thereof, the crystals become coarse, the brightness of the plating layer decreases, and the surface tone becomes dark. On the other hand, when the plating current density exceeds 300 A / dm 2 and becomes large, the concentration of zinc ions at the cathode interface becomes 0, and as a result, plating burn is likely to occur on the surface of the plating layer. Therefore, in the present invention, the plating current density should be limited to the range of 200 to 300 A / dm 2 .
【００１６】この発明においては、電気亜鉛めっき浴中
に光沢剤のような添加剤が添加されていないので、電気
亜鉛めっき浴の粘度は低下する。従って、このような電
気亜鉛めっき浴を使用し、鋼板を電気亜鉛めっきする
と、陰極界面における亜鉛イオンの移動が促進される結
果、亜鉛結晶が微細化且つ平滑化し、亜鉛めっき層の表
面の明度が向上する。In the present invention, since no additive such as a brightening agent is added to the electrogalvanizing bath, the viscosity of the electrogalvanizing bath is lowered. Therefore, when using such an electrogalvanizing bath to electrogalvanize a steel sheet, the migration of zinc ions at the cathode interface is promoted, resulting in finer and smoother zinc crystals, and the brightness of the surface of the galvanized layer. improves.
【００１７】電導度補助剤は、電気泳動に関与して、限
界電流密度に影響を及ぼす。即ち、高電流密度におけ
る、陰極界面の亜鉛イオンの移動には、拡散による移動
に加えて、電気泳動による移動が大きく寄与する。電気
泳動によって移動する亜鉛イオンは、陰極界面の拡散層
内に生ずる電界の強さに比例する。従って、強い電界が
形成されるめっき浴即ち電導度補助剤が添加されていな
い電気亜鉛めっき浴を使用し、鋼板を電気亜鉛めっきす
ると、電気泳動の効果が大きくなり、陰極界面における
亜鉛イオンの移動が促進される結果、亜鉛結晶が微細化
且つ平滑化し、亜鉛めっき層の表面の明度が向上する。The conductivity auxiliary agent participates in electrophoresis and affects the limiting current density. In other words, migration of zinc ions at the cathode interface at high current density is greatly affected by migration as well as migration by diffusion. Zinc ions that move by electrophoresis are proportional to the strength of the electric field generated in the diffusion layer at the cathode interface. Therefore, when a galvanizing bath is used in which a strong electric field is formed, that is, an electrogalvanizing bath to which a conductivity auxiliary agent is not added, and electrogalvanizing a steel sheet, the electrophoretic effect is increased, and the migration of zinc ions at the cathode interface As a result, the zinc crystals become finer and smoother, and the brightness of the surface of the zinc plating layer is improved.
【００１８】電気亜鉛めっき浴中の亜鉛イオンの含有量
は、 ZnSO4・7H2O換算で400 〜600g/l の範囲内に限定
すべきである。亜鉛イオンの含有量が、 ZnSO4・7H2O換
算で400 g/l 未満では、めっき浴中の亜鉛イオンの濃度
が減少して、許容電流密度が低下する結果、200 A/dm2
以上の高電流密度では、安定した電気亜鉛めっきを行う
ことができなくなる。亜鉛イオンの含有量を、 ZnSO4・
7H2O換算で400 g/l 以上にすれば、200 A/dm2 以上の高
電流密度で、安定した電気亜鉛めっきを行うことが可能
になる。しかしながら、亜鉛イオンの含有量が、 ZnSO4
・7H2O換算で600 g/l を超えると、硫酸亜鉛がめっき浴
中に十分に溶解せず、めっき浴の粘度が上昇する結果、
陰極界面における亜鉛イオンの拡散層が厚くなって、許
容電流密度が低下する。なお、めっき浴中の亜鉛は、 Z
nSO4・7H2Oに限られるものではなく、他の物質に含有さ
れた状態であってもよい。The content of zinc ions in the electrogalvanizing bath should be limited to the range of 400 to 600 g / l in terms of ZnSO 4 .7H 2 O. The content of zinc ions, the ZnSO 4 · 7H 2 O in terms of less than 400 g / l, and the concentration of zinc ions in the plating bath is reduced, the allowable current results density decreases, 200 A / dm 2
With the above high current density, stable electrogalvanizing cannot be performed. The content of zinc ion is ZnSO 4
If it is 400 g / l or more in terms of 7H 2 O, stable electrogalvanizing can be performed at a high current density of 200 A / dm 2 or more. However, if the zinc ion content is ZnSO 4
・ When it exceeds 600 g / l in terms of 7H 2 O, zinc sulfate is not sufficiently dissolved in the plating bath, resulting in an increase in the viscosity of the plating bath.
The zinc ion diffusion layer at the cathode interface becomes thick, and the allowable current density decreases. Zinc in the plating bath is Z
NSO 4 · 7H not limited to 2 O, it may be in the state of being contained in other substances.
【００１９】電気亜鉛めっき浴の温度は、60〜80℃の範
囲内に限定すべきである。電気亜鉛めっき浴の温度が60
℃未満では、めっき浴の粘度が上昇する結果、陰極界面
における拡散層が厚くなり、許容電流密度の低下を招
く。めっき浴の温度を60℃以上にすれば、めっき浴の粘
度が低下して、陰極界面における拡散層が薄くなり、許
容電流密度が高くなる。更に、亜鉛イオンの移動が促進
されて、めっき層の表面が微細化且つ平滑化し、めっき
層の明度が向上して、表面外観が向上する。一方、めっ
き浴の温度が80℃を超えて高くなると、付帯設備の防熱
のために設備費用が嵩む問題が生ずる。The temperature of the electrogalvanizing bath should be limited to the range of 60-80 ° C. The temperature of the electrogalvanizing bath is 60
If the temperature is lower than 0 ° C, the viscosity of the plating bath increases, and as a result, the diffusion layer at the cathode interface becomes thicker and the allowable current density decreases. When the temperature of the plating bath is set to 60 ° C. or higher, the viscosity of the plating bath decreases, the diffusion layer at the cathode interface becomes thin, and the allowable current density increases. Furthermore, the movement of zinc ions is promoted, the surface of the plating layer is made finer and smoother, the brightness of the plating layer is improved, and the surface appearance is improved. On the other hand, if the temperature of the plating bath rises above 80 ° C., there is a problem that the cost of the equipment increases due to the heat insulation of the auxiliary equipment.
【００２０】電気亜鉛めっき浴のpH値は、０〜１の範囲
内に限定すべきである。電気亜鉛めっき浴のpH値が低い
ほど、水素イオンの発生が増加する結果、電導度が向上
し、電力コストが小になる。また、陰極界面において水
素が発生し、発生した水素の気泡によって陰極界面にお
ける拡散層が攪拌される結果、拡散層の厚さが小さくな
り、許容電流密度が高くなる。更に、上述した攪拌作用
によって、拡散層における亜鉛イオンの移動が促進され
る結果、めっき層の表面が微細化且つ平滑化し、亜鉛め
っき層の明度が向上して、表面色調が白くなる。めっき
浴のpH値が１超では、上述した作用に所望の効果が得ら
れない。一方、めっき浴のpH値が０未満では、陰極界面
における水素の発生が過剰になる結果、電解効率が減少
する問題が生ずる。The pH value of the electrogalvanizing bath should be limited to the range of 0 to 1. The lower the pH value of the electrogalvanizing bath, the more hydrogen ions are generated, resulting in improved conductivity and lower power costs. In addition, hydrogen is generated at the cathode interface, and as a result of the generated hydrogen bubbles stirring the diffusion layer at the cathode interface, the thickness of the diffusion layer is reduced and the allowable current density is increased. Further, as a result of promoting the movement of zinc ions in the diffusion layer by the above-mentioned stirring action, the surface of the plating layer becomes finer and smoother, the brightness of the zinc plating layer is improved, and the surface color tone becomes white. If the pH value of the plating bath exceeds 1, the desired effect cannot be obtained in the above-mentioned action. On the other hand, when the pH value of the plating bath is less than 0, hydrogen is excessively generated at the cathode interface, resulting in a problem that electrolysis efficiency is reduced.
【００２１】電気めっき槽内における電気亜鉛めっき浴
の流速は、２m/s 以上とすべきである。めっき浴の流速
が２m/s 未満では、陰極界面における拡散層が厚くなっ
て、許容電流密度が低下する結果、200 〜300 A/dm2 の
電流密度により、鋼板を電気めっきした場合に、めっき
層にめっき焼けが生じやすくなり、めっき層の表面外観
が劣化する。The flow rate of the electrogalvanizing bath in the electroplating bath should be at least 2 m / s. If the flow velocity of the plating bath is less than 2 m / s, the diffusion layer at the cathode interface becomes thicker and the allowable current density decreases, resulting in a current density of 200 to 300 A / dm 2 when the steel sheet is electroplated. Plating burn is likely to occur in the layer, and the surface appearance of the plated layer deteriorates.
【００２２】この発明の方法によって、鋼板の少なくと
も１つの表面上に形成される電気亜鉛めっき層のめっき
量は、鋼板の片面当たり10〜100 g/m2の範囲内に限定す
べきである。めっき量が、鋼板の片面当たり10g/m2未満
では、電気亜鉛めっき鋼板の耐食性が劣化する。一方、
めっき量が、鋼板の片面当たり100 g/m2を超えると、電
気亜鉛めっき鋼板の加工性が劣化する。The amount of electrogalvanized layer formed on at least one surface of the steel sheet by the method of the present invention should be limited to the range of 10 to 100 g / m 2 per side of the steel sheet. If the amount of plating is less than 10 g / m 2 on one side of the steel sheet, the corrosion resistance of the electrogalvanized steel sheet deteriorates. on the other hand,
If the amount of plating exceeds 100 g / m 2 on one side of the steel sheet, the workability of the electrogalvanized steel sheet deteriorates.
【００２３】[0023]
【実施例】次に、この発明を、実施例により、比較例と
対比しながら更に詳述する。下記に示す、本発明の範囲
内の条件で、板厚0.6 mmの冷延鋼板に対し電気亜鉛めっ
きを施して、鋼板の表面上に、40g/m2の量の電気亜鉛め
っき層を形成し、表１に示した本発明の方法による電気
亜鉛めっき鋼板の供試体（以下、本発明供試体という）
No. １〜12を調製した。EXAMPLES Next, the present invention will be described in more detail by way of examples and in comparison with comparative examples. Under the conditions shown below, within the scope of the present invention, electrogalvanizing a cold-rolled steel sheet having a plate thickness of 0.6 mm to form an electrogalvanized layer in an amount of 40 g / m 2 on the surface of the steel sheet. , Samples of electrogalvanized steel sheet according to the method of the present invention shown in Table 1 (hereinafter referred to as samples of the present invention)
Nos. 1 to 12 were prepared.
【００２４】めっき浴の組成： 硫酸亜鉛 (ZnSO4・7H2O) ：400 〜600 g/l 、 めっき浴のpH値： ０〜１、 めっき浴の温度： 60〜80℃、 めっき浴の流速： ２〜６m/s 、 めっき電流密度：200 〜300 A/dm2 、 陽極 ：酸化イリジウムからなる不溶性陽極。Composition of plating bath: Zinc sulfate (ZnSO 4 .7H 2 O): 400-600 g / l, pH value of plating bath: 0-1, Temperature of plating bath: 60-80 ° C., Flow velocity of plating bath : 2 to 6 m / s, Plating current density: 200 to 300 A / dm 2 , Anode: Insoluble anode made of iridium oxide.
【００２５】[0025]
【表１】 [Table 1]
【００２６】比較のために、下記に示す、その少なくと
も１つが本発明の範囲外の条件で、板厚0.6 mmの冷延鋼
板に対し電気亜鉛めっきを施して、鋼板の表面上に、40
g/m2の量の電気亜鉛めっき層を形成し、表２に示した本
発明の範囲外の方法による電気亜鉛めっき鋼板の供試体
（以下、比較用供試体という）No. １〜12を調製した。For comparison, at least one of the following is subjected to electrogalvanization on a cold-rolled steel sheet having a thickness of 0.6 mm under the condition that at least one of them is outside the scope of the present invention, and 40
An electrogalvanized layer having an amount of g / m 2 was formed, and electrogalvanized steel sheet specimens (hereinafter referred to as comparative specimens) Nos. 1 to 12 produced by a method outside the scope of the present invention shown in Table 2 were prepared. Prepared.
【００２７】めっき浴の組成： 硫酸亜鉛 (ZnSO4・7H2O) ：400 〜600 g/l 、 硫酸ソーダ(Na2SO4) ： 0 〜 70 g/l 、 めっき浴のpH値： ０〜2.5 めっき浴の温度： 40〜80℃、 めっき浴の流速： １〜３m/s 、 めっき電流密度： 40 〜300 A/dm2 、 陽極 ：酸化イリジウムからなる不溶性陽極。Composition of plating bath: Zinc sulfate (ZnSO 4 .7H 2 O): 400 to 600 g / l, sodium sulfate (Na 2 SO 4 ): 0 to 70 g / l, pH value of plating bath: 0 to 0 2.5 Plating bath temperature: 40 to 80 ° C., Plating bath flow rate: 1 to 3 m / s, Plating current density: 40 to 300 A / dm 2 , Anode: Insoluble anode made of iridium oxide.
【００２８】[0028]
【表２】 [Table 2]
【００２９】このようにして調製した本発明供試体およ
び比較用供試体の各々について、スガ試験機（株）製の
多光源分光測色計 MSC-1S-2Bを使用し、Lab 表色系の明
度指数Ｌ値を測定し、その測定結果を、表１および表２
に併せて示した。なお、表１および表２中におけるＬ値
欄の「ムラ」は、めっき層の表面に縞模様が現れ、めっ
き層の表面形状が不均一になったことを示し、そして、
Ｌ値欄の「ヤケ」は、めっき層にめっき焼けが発生した
ことを示す。For each of the sample of the present invention and the sample for comparison thus prepared, a multi-source spectrophotometer MSC-1S-2B manufactured by Suga Test Instruments Co., Ltd. The lightness index L value was measured, and the measurement results are shown in Table 1 and Table 2.
Are also shown. In addition, "unevenness" in the L value column in Table 1 and Table 2 indicates that a striped pattern appeared on the surface of the plating layer and the surface shape of the plating layer became non-uniform, and
“Discoloration” in the L value column indicates that plating burn occurred in the plating layer.
【００３０】表２から明らかなように、硫酸亜鉛(ZnSO4
・7H2O) の含有量が本発明の範囲を外れて少ないめっき
浴を使用して電気亜鉛めっきした比較用供試体No. １〜
３の場合は、めっき層の表面にムラが発生した。電導度
補助剤として硫酸ソーダが添加されためっき浴を使用し
て電気亜鉛めっきした比較用供試体No. ４および５の場
合は、Ｌ値が低く表面色調が黒っぽかった。As is clear from Table 2, zinc sulfate (ZnSO 4
・ Comparison specimen No. 1 for electrogalvanizing using a plating bath containing less 7H 2 O) than the range of the present invention
In the case of 3, unevenness occurred on the surface of the plating layer. In Comparative Samples Nos. 4 and 5 which were electrogalvanized using a plating bath to which sodium sulfate was added as a conductivity auxiliary agent, the L value was low and the surface color tone was dark.
【００３１】pH値が本発明の範囲を外れて高いめっき浴
を使用して電気亜鉛めっきした比較用供試体No. ６およ
び７の場合は、めっき層の表面にムラが発生した。めっ
き浴の温度が本発明の範囲を外れて低いめっき浴を使用
して電気亜鉛めっきした比較用供試体No. ８および９の
場合は、めっき層の表面にムラが発生した。In the case of Comparative Specimen Nos. 6 and 7 which were electrogalvanized using a high plating bath having a pH value outside the range of the present invention, unevenness occurred on the surface of the plating layer. In the case of Comparative Specimen Nos. 8 and 9 in which the temperature of the plating bath was outside the range of the present invention and the plating bath was low and electrogalvanized, unevenness occurred on the surface of the plating layer.
【００３２】めっき浴の流速が本発明の範囲を外れて低
いめっき浴を使用して電気亜鉛めっきした比較用供試体
No. 10の場合は、めっき層の表面にヤケが発生し、めっ
き浴の流速が本発明の範囲を外れて低いめっき浴を使用
して電気亜鉛めっきした比較用供試体No. 11の場合は、
めっき層の表面にムラが発生した。そして、めっき電流
密度が本発明の範囲を外れて低い条件で電気亜鉛めっき
した比較用供試体No.12の場合は、Ｌ値が低く表面色調
が黒っぽかった。A comparative test piece electrogalvanized using a plating bath having a low plating bath flow rate outside the range of the present invention.
In the case of No. 10, in the case of Comparative Specimen No. 11 for electrogalvanizing using a plating bath in which a burn was generated on the surface of the plating layer and the flow velocity of the plating bath was outside the range of the present invention ,
There was unevenness on the surface of the plating layer. Then, in the case of comparative sample No. 12 which was electrogalvanized under conditions where the plating current density was outside the range of the present invention and was low, the L value was low and the surface color tone was dark.
【００３３】これに対し、本発明の範囲内の条件で電気
亜鉛めっきした本発明供試体No. １から12の場合は、何
れも、Ｌ値即ち明度指数が85以上で高く、表面色調が白
く、表面外観が優れていた。On the other hand, in the case of the test pieces Nos. 1 to 12 of the present invention which were electrogalvanized under the conditions within the scope of the present invention, in all cases, the L value, that is, the lightness index was higher than 85 and the surface color tone was white , The surface appearance was excellent.
【００３４】[0034]
【発明の効果】以上述べたように、この発明の方法によ
り、電気亜鉛めっき浴中に、電導度補助剤および光沢剤
等を添加せず、 ZnSO4・7H2O換算で400 〜600 g/l の範
囲内の量の亜鉛イオンを含有する、高温且つ高流速で低
pH値の電気亜鉛めっき浴中において、不溶性陽極を使用
し、200 〜300 A/dm2 の高電流密度で、鋼板を電気亜鉛
めっきすれば、電気亜鉛めっき浴の電導度が増加し、省
電力化が図られ、めっき浴の粘度の上昇や、陰極界面に
おける拡散層の厚さの増加等の生ずることがなく、そし
て、不溶性陽極の寿命に悪影響が生ぜず、明度が85以上
の表面色調が白い、表面外観の優れた電気亜鉛めっき鋼
板を製造することができる、工業上有用な効果がもたら
される。As described above, according to the method of the present invention, 400 to 600 g / ZnSO 4 .7H 2 O conversion is performed without adding a conductivity auxiliary agent and a brightening agent in the electrogalvanizing bath. containing zinc ion in the range of l
In an electrogalvanizing bath with a pH value, if an insoluble anode is used and the steel sheet is electrogalvanized at a high current density of 200 to 300 A / dm 2 , the electric conductivity of the electrogalvanizing bath is increased, resulting in power saving. The increase in the viscosity of the plating bath and the increase in the thickness of the diffusion layer at the cathode interface do not occur, and the life of the insoluble anode is not adversely affected, and the surface color tone with a brightness of 85 or more is obtained. An industrially useful effect that can produce a white electrogalvanized steel sheet having an excellent surface appearance is provided.
Claims (1)
600 g/l 含有する、浴温:60 〜80℃、pH値：０〜１、流
速：２m/s 以上の電気亜鉛めっき浴中において、不溶性
陽極を使用し、200 〜300 A/dm2 の電流密度により、鋼
板を電気亜鉛めっきして、前記鋼板の少なくとも１つの
表面上に、前記鋼板の片面当たり10〜100 g/m2の量の電
気亜鉛めっき層を形成することを特徴とする、表面外観
の優れた電気亜鉛めっき鋼板の製造方法。1. Zinc ion is 400 to 100 in terms of ZnSO 4 .7H 2 O.
In an electrogalvanizing bath containing 600 g / l, bath temperature: 60-80 ° C, pH value: 0-1, flow rate: 2 m / s or more, using an insoluble anode, 200-300 A / dm 2 Electrogalvanizing the steel sheet with a current density to form an electrogalvanized layer on at least one surface of the steel sheet in an amount of 10 to 100 g / m 2 per side of the steel sheet, A method for producing an electrogalvanized steel sheet having an excellent surface appearance.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18634392A JPH062193A (en) | 1992-06-19 | 1992-06-19 | Manufacture of electrogalvanized steel plate excelling in surface appearance |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18634392A JPH062193A (en) | 1992-06-19 | 1992-06-19 | Manufacture of electrogalvanized steel plate excelling in surface appearance |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH062193A true JPH062193A (en) | 1994-01-11 |
Family
ID=16186700
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP18634392A Pending JPH062193A (en) | 1992-06-19 | 1992-06-19 | Manufacture of electrogalvanized steel plate excelling in surface appearance |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH062193A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH07278880A (en) * | 1994-04-15 | 1995-10-24 | Nippon Steel Corp | Production of electrogalvanized steel sheet excellent surface appearance |
-
1992
- 1992-06-19 JP JP18634392A patent/JPH062193A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH07278880A (en) * | 1994-04-15 | 1995-10-24 | Nippon Steel Corp | Production of electrogalvanized steel sheet excellent surface appearance |
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