JPS6138274B2 - - Google Patents
Info
- Publication number
- JPS6138274B2 JPS6138274B2 JP57087266A JP8726682A JPS6138274B2 JP S6138274 B2 JPS6138274 B2 JP S6138274B2 JP 57087266 A JP57087266 A JP 57087266A JP 8726682 A JP8726682 A JP 8726682A JP S6138274 B2 JPS6138274 B2 JP S6138274B2
- Authority
- JP
- Japan
- Prior art keywords
- plating
- plating bath
- workability
- corrosion resistance
- current density
- 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.)
- Expired
Links
- 238000007747 plating Methods 0.000 claims description 105
- 229910000831 Steel Inorganic materials 0.000 claims description 49
- 239000010959 steel Substances 0.000 claims description 49
- 230000007797 corrosion Effects 0.000 claims description 33
- 238000005260 corrosion Methods 0.000 claims description 33
- 229910018605 Ni—Zn Inorganic materials 0.000 claims description 27
- 229910045601 alloy Inorganic materials 0.000 claims description 27
- 239000000956 alloy Substances 0.000 claims description 27
- 238000004519 manufacturing process Methods 0.000 claims description 8
- 239000011701 zinc Substances 0.000 description 47
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 46
- 239000000203 mixture Substances 0.000 description 11
- 238000000034 method Methods 0.000 description 9
- 230000007423 decrease Effects 0.000 description 7
- 238000009713 electroplating Methods 0.000 description 7
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 6
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- LGQLOGILCSXPEA-UHFFFAOYSA-L nickel sulfate Chemical compound [Ni+2].[O-]S([O-])(=O)=O LGQLOGILCSXPEA-UHFFFAOYSA-L 0.000 description 4
- 229910000363 nickel(II) sulfate Inorganic materials 0.000 description 4
- 230000002265 prevention Effects 0.000 description 4
- NWONKYPBYAMBJT-UHFFFAOYSA-L zinc sulfate Chemical compound [Zn+2].[O-]S([O-])(=O)=O NWONKYPBYAMBJT-UHFFFAOYSA-L 0.000 description 4
- 229910000368 zinc sulfate Inorganic materials 0.000 description 4
- 229960001763 zinc sulfate Drugs 0.000 description 4
- 229910001335 Galvanized steel Inorganic materials 0.000 description 3
- 229910001297 Zn alloy Inorganic materials 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000011156 evaluation Methods 0.000 description 3
- 239000008397 galvanized steel Substances 0.000 description 3
- 238000011160 research Methods 0.000 description 3
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- 230000006866 deterioration Effects 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000004070 electrodeposition Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 229910000765 intermetallic Inorganic materials 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000003973 paint Substances 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 235000002639 sodium chloride Nutrition 0.000 description 2
- 238000005728 strengthening Methods 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 229920000298 Cellophane Polymers 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- VMHLLURERBWHNL-UHFFFAOYSA-M Sodium acetate Chemical compound [Na+].CC([O-])=O VMHLLURERBWHNL-UHFFFAOYSA-M 0.000 description 1
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000005238 degreasing Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000007710 freezing Methods 0.000 description 1
- 230000008014 freezing Effects 0.000 description 1
- 238000005246 galvanizing Methods 0.000 description 1
- 239000012770 industrial material Substances 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- LNOPIUAQISRISI-UHFFFAOYSA-N n'-hydroxy-2-propan-2-ylsulfonylethanimidamide Chemical compound CC(C)S(=O)(=O)CC(N)=NO LNOPIUAQISRISI-UHFFFAOYSA-N 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 238000010422 painting Methods 0.000 description 1
- 238000010587 phase diagram Methods 0.000 description 1
- 238000005554 pickling Methods 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 235000017281 sodium acetate Nutrition 0.000 description 1
- 239000001632 sodium acetate Substances 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 150000003467 sulfuric acid derivatives Chemical class 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
Description
この発明は、加工性および耐食性に優れたNi
−Zn合金電気メツキ鋼板の製造方法に関するも
のである。
工業用材料の主力である鉄鋼には省資源の見地
から耐食性の向上が求められている。特に鉄鋼需
要の中で大きな比重を占める自動車工業界では、
北米や北欧に代表される降雪地帯で冬期に路面の
凍結防止用に散布される岩塩などの融雪剤による
車体腐食が大きな問題になつており、車体防錆力
の強化が必要とされている。
車体防錆強化対策として表面処理鋼板の使用が
急速に増加している。車体防錆強化上、表面処理
鋼板に要求される性能の主体は、塗装された部分
と合わせ目部分等、塗装されずに残つた部分の耐
食性および加工性である。
従来、上記表面処理鋼板としては、亜鉛メツキ
鋼板が使用されてきたが、亜鉛メツキは腐食速度
が大きいため厚メツキが必要となる。このために
スクラツプ処理上問題となる他、塗膜下での腐食
反応に起因する塗膜のふくれが生じるので、亜鉛
メツキ鋼板は、車体防錆材料として不十分であ
る。このような状況下で、Ni−Zn、Fe−Zn、Co
−Cr−Znなどの合金電気メツキ鋼板が優れた性
能を持つ材料であることが明らかにされてきた。
特に、未塗装部分で従来の亜鉛メツキ鋼板の５〜
10倍の耐食性を優し、塗装後も優れた耐食性を示
すNi−Zn合金電気メツキ鋼板が車体防錆力強化
に適した材料として注目されている。
Ni−Zn合金電気メツキ鋼板は、Ni含有率が10
％以上で再結晶構造としてγ相が形成されると、
優れた裸耐食性を示すことが知られている。従つ
て、高耐食性を目的としたNi−Zn合金電気メツ
キ鋼板は上記組成を持つように製造される。
電気メツキ鋼板の生産性からみると、高電流密
度で操業できることが望ましい。従来、Ni−Zn
合金電気メツキに使用されている電流密度は最大
30A/dm2程度であり、通常の電気亜鉛メツキの電
流密度に比べると電流密度はまだ低く生産性は十
分とは云えない。
高耐食性を保持しながら高電流密度で電気メツ
キを行なう方は、例えば、特開昭55−152194号公
報に開示されている。この方法は、メツキ浴と鋼
板との相対速度を20mpm以上に維持し、これに
よつて、メツキ皮膜組成を耐食性の優れた範囲に
保ちながら、100A/dm2程度の高電流密度で電気
メツキを行なう方法である。しかし、単に、メツ
キ浴と鋼板との相対速度を20mpm以上にするだ
けでは、メツキ皮膜組成を高耐食性の優れたもの
にすることができないことは明らかであり、メツ
キ浴の流速のみでなく、メツキ浴の組成やPHもメ
ツキ皮膜組成に影響を及ぼす。
別の方法として、日本鉄鋼協会発行の「鉄と
鋼」第67巻No.4S−333には、メツキ条件を電流
密度を10〜40A/dm2の範囲で検討し、メツキ浴組
成、メツキ浴流速を適宜選ぶことにより40A/dm2
までの電流密度範囲でγ相が得られることが記載
されている。しかし、PHの許容上限がどこかは明
示されていない他、PH許容上限とNi2+／Zi2+との
関係の有無については全く不明であり、後述する
ようにメツキ皮膜の加工性が保障されない。
メツキ皮膜の加工性を考慮した製造技術として
は、特公昭49−32172号公報にPH＝4.0〜4.5とす
ることによりメツキ皮膜の内部応力を低下させ、
これによつて延性を得る方法が記載されている
が、電流密度が4.3〜10.8A/dm2と低い。
以上のように、従来、耐食性と加工性共に考慮
しながら高電流密度でNi−Zn合金電気メツキ鋼
板を製造する技術は十分確立されていない。
本願発明者等は、上述のような観点から、メツ
キ浴のPH、メツキ浴と鋼板との相対速度、メツキ
浴組成等のメツキ条件が、Ni−Zn合金電気メツ
キ鋼板の耐食性および加工性に及ぼす影響につき
鋭意検討を重ねた。この結果、次の如き知見を得
た。
(1) メツキ浴中のNi2+／（Zn2+＋Ni2+）を0.55以
上とし、
(2) メツキ浴のPHを、メツキ浴と鋼板との相対速
度、メツキ浴組成に応じたPHの上限値以下のPH
とし、しかも、
(3) メツキ浴のZn2+濃度を20ｇ/以上とする条
件でメツキを行なえば、30A/dm2以上の高電流
密度で耐食性および加工性の優れたNi−Zn合
金電気メツキ鋼板の製造が可能となる。
この発明は、上記知見に基づきなされたもので
あつて、
Ni−Zn合金電気メツキ鋼板を製造する方法に
おいて、PHが次式で表わされるPHL以下で、
PHL＝0.85υ＋6.0（Ｚｎ２＋／Ｚｎ２＋＋Ｎｉ２＋−0.
1）
但し、
υ：メツキ浴と鋼板との相対速度（m/S）。
Zn2+が20ｇ/以上で、しかも、Ni2+／（Zn2+
＋Ni2+）が0.55から0.90の範囲内であるメツキ浴
を使用して、50A/dm2以上の高電流密度でメツキ
を行なうことに特徴を有する。
この発明を詳細に説明する。
Ni−Zn合金電気メツキ浴は、硫酸浴、塩化
浴、スルフアミン酸浴などから得ることができる
が、自溶性アノード、不溶性アノードの何れも使
用可能であり、経済性もある点で硫酸塩を主体と
したメツキ浴が実用的である。
第１表に、次に示す条件で硫酸浴から電析した
Ni−Zn合金メツキ皮膜の加工性が、電流密度に
よつてどのような影響を受けるか調べた結果を示
す。
条 件
メツキ浴組成 硫酸亜鉛：150ｇ/、
硫酸ニツケル：350ｇ/、
無水硫酸ナトリウム：60ｇ/（電導度補助
剤）、
メツキ浴のPH：2.0、
メツキ浴と鋼板との相対速度：0.7m/S、
メツキ浴の温度：50℃、
メツキ量：20ｇ/m2。
This invention utilizes Ni, which has excellent workability and corrosion resistance.
-This invention relates to a method for producing Zn alloy electroplated steel sheets. Steel, the mainstay of industrial materials, is required to have improved corrosion resistance from the perspective of resource conservation. Especially in the automobile industry, which accounts for a large proportion of steel demand,
Corrosion of car bodies caused by snow-melting agents such as rock salt, which are sprayed to prevent roads from freezing during the winter in snowy regions such as North America and Northern Europe, has become a major problem, and there is a need to strengthen car body rust prevention capabilities. The use of surface-treated steel sheets is rapidly increasing as a measure to strengthen car body rust prevention. The main performance requirements of surface-treated steel sheets for strengthening car body rust prevention are the corrosion resistance and workability of the painted parts and the parts that remain unpainted, such as seams. Conventionally, galvanized steel sheets have been used as the above-mentioned surface-treated steel sheets, but since galvanized steel sheets have a high corrosion rate, thick plating is required. This causes problems in scrapping, and also causes blistering of the paint film due to corrosion reactions under the paint film, making galvanized steel sheets insufficient as a rust-preventing material for car bodies. Under such circumstances, Ni−Zn, Fe−Zn, Co
It has been revealed that alloy electroplated steel sheets such as -Cr-Zn are materials with excellent performance.
In particular, in unpainted areas, 5~
Ni-Zn alloy electroplated steel sheet, which has 10 times better corrosion resistance and exhibits excellent corrosion resistance even after painting, is attracting attention as a material suitable for strengthening car body rust prevention. Ni-Zn alloy electroplated steel sheet has a Ni content of 10
% or more, when the γ phase is formed as a recrystallized structure,
It is known to exhibit excellent bare corrosion resistance. Therefore, a Ni-Zn alloy electroplated steel sheet intended for high corrosion resistance is manufactured to have the above composition. From the viewpoint of productivity of electroplated steel sheets, it is desirable to be able to operate at high current density. Conventionally, Ni−Zn
The current density used for alloy electroplating is up to
The current density is about 30A/dm2, which is still low compared to the current density of normal electrolytic galvanizing, and the productivity cannot be said to be sufficient. A method of electroplating at high current density while maintaining high corrosion resistance is disclosed in, for example, Japanese Patent Application Laid-open No. 152194/1983. This method maintains the relative speed between the plating bath and the steel plate at 20 mpm or more, thereby maintaining the plating film composition within a range with excellent corrosion resistance while electroplating is performed at a high current density of about 100 A/dm2. This is the way to do it. However, it is clear that simply increasing the relative speed between the plating bath and the steel plate to 20 mpm or higher will not make the plating film composition excellent in high corrosion resistance. Bath composition and pH also affect the plating film composition. As another method, in ``Tetsu to Hagane'' Vol. 67 No. 4S-333 published by the Japan Iron and Steel Institute, the plating conditions are examined with the current density in the range of 10 to 40 A/dm 2 , and the plating bath composition, plating bath composition, 40A/dm 2 by selecting the flow rate appropriately
It is described that the γ phase can be obtained in a current density range up to However, it is not specified where the allowable upper limit of PH is, and it is also completely unclear whether there is a relationship between the allowable PH upper limit and Ni 2+ /Zi 2+ , and as will be explained later, the workability of the plating film is not guaranteed. Not done. As a manufacturing technology that takes into consideration the workability of the plating film, Japanese Patent Publication No. 49-32172 describes a process in which the internal stress of the plating film is reduced by setting the pH to 4.0 to 4.5.
A method of obtaining ductility by this method has been described, but the current density is as low as 4.3 to 10.8 A/dm 2 . As described above, the technology for manufacturing Ni-Zn alloy electroplated steel sheets at high current density while taking both corrosion resistance and workability into consideration has not been sufficiently established. From the above-mentioned viewpoint, the present inventors have investigated the effects of plating conditions such as the pH of the plating bath, the relative speed between the plating bath and the steel sheet, and the composition of the plating bath on the corrosion resistance and workability of Ni-Zn alloy electroplated steel sheets. We have carefully considered the impact. As a result, the following findings were obtained. (1) Ni 2+ / (Zn 2+ + Ni 2+ ) in the plating bath should be 0.55 or more, (2) The pH of the plating bath should be adjusted according to the relative speed between the plating bath and the steel plate, and the composition of the plating bath. PH below the upper limit
Moreover, (3) If plating is performed under the condition that the Zn 2+ concentration in the plating bath is 20 g/min or more, Ni-Zn alloy electroplating with excellent corrosion resistance and workability can be achieved at a high current density of 30 A/dm 2 or higher. It becomes possible to manufacture steel plates. The present invention has been made based on the above knowledge, and provides a method for manufacturing a Ni-Zn alloy electroplated steel sheet, in which PH is less than or equal to PH L expressed by the following formula, and PH L = 0.85υ + 6.0 (Zn 2+ /Zn 2+ +Ni 2+ -0.
1) However, υ is the relative speed between the plating bath and the steel plate (m/S). Zn 2+ is 20g/ or more, and Ni 2+ / (Zn 2+
It is characterized in that plating is performed at a high current density of 50 A/dm 2 or more using a plating bath in which +Ni 2+ ) is in the range of 0.55 to 0.90. This invention will be explained in detail. Ni-Zn alloy electroplating baths can be obtained from sulfuric acid baths, chloride baths, sulfamic acid baths, etc., but both self-soluble anodes and insoluble anodes can be used, and sulfate salts are mainly used due to economic efficiency. A bath with a velvety surface is practical. Table 1 shows the results of electrodeposition from a sulfuric acid bath under the conditions shown below.
The results of an investigation into how the workability of a Ni-Zn alloy plating film is affected by current density are shown. Conditions Plating bath composition Zinc sulfate: 150g/, Nickel sulfate: 350g/, Anhydrous sodium sulfate: 60g/(conductivity aid), PH of plating bath: 2.0, Relative speed between plating bath and steel plate: 0.7m/S , Temperature of plating bath: 50℃, Amount of plating: 20g/m 2 .
【表】
メツキ皮膜の加工性は、メツキ皮膜が外側に出
るようにメツキ鋼板を180゜密着曲げしたのち、
セロテープによる剥離程度を目視により評価した
ものであり、評価基準は、第２表の通りである。[Table] The workability of the plating film is determined by bending the plating steel plate closely at 180° so that the plating film is exposed to the outside.
The degree of peeling by cellophane tape was visually evaluated, and the evaluation criteria are as shown in Table 2.
【表】
後述する説明において、メツキ皮膜の加工性は
何れも上記方法により試験評価したものである。
第１表から明らかなように、メツキ電流密度が
30A/dm2を越えると、メツキ皮膜の加工性が低下
することがわかる。これは次の理由によるものと
考えられる。すなわち、
(1) 一般に金属間化合物の変形能は純金属のそれ
に比べて小さく、このために加工性が悪い。
Ni−Zn合金のγ相は、状態図によれば室温で
Ni含有率が13.5〜約20％の範囲で存在し、化学
量論的金属間化合物としては、Ni含有率が17.6
％のNi5Zn21が存在することが示されている。
Ni含有率が17.6％以下ではNi5Zn21の結晶格子
中に空孔が存在するので、加工に際して金属原
子はある程度移動可能と推定される。このこと
からγ相のうちでNi含有率が低いものは相対
的に加工が容易であるが、Ni含有率の増加と
ともに加工性が低下してメツキ皮膜の剥離が起
こる。
(2) 後述するように、高電流密度を適用すると鉄
地（鋼板）とメツキ浴との界面におけるメツキ
浴のPH、即ち、界面PHは上昇する。界面PHが
5.1以上では、Zn（OH）2が生成するのでZn
（OH）2が共析する可能性がある。界面に析出し
たZn（OH）2は、鉄地とNi−Zn合金の金属結合
を遮断するので、Zn（OH）2による鉄地表面の
被覆率が高まると、鉄地とメツキ皮膜との結合
力が弱まる。加工による力が加わつたときに結
合力の弱い界面で剥離が起こる。
Ni−Zn合金電析におけるメツキ皮膜のNi含
有率は、メツキ浴のPHが上昇するに伴つて大き
くなり、Zn（OH）2の共析も促進されると考え
られるが、電極反応が実際に起るのは鋼板とメ
ツキ浴との界面であり、Ni含有率、Zn（OH）2
の共析量を決定するのは界面のPHである。界面
PHはメツキ浴の拡散層の外側からのH+の供給
と、水素ガス発生とのバランスによつて決ま
る。H+の供給は物質移動の問題であり、カソ
ード（鋼板）とメツキ浴の相対速度を高めるこ
とにより拡散層を薄くすればH+の供給は容易
になり、界面PHが下がる方向に向く。また、本
願発明者等の研究によれば、高電流密度でNi
−Zn合金メツキを行なうと、優先析出する
Zn2+のカソードへの供給が不足し、その不足分
のカソード反応が水素ガス発生反応となり、界
面PHは上昇する。
以上のことから、電流密度の増加によりメツキ
皮膜の加工性が低下する第１表の結果は、メツキ
浴のバルク側から界面へのH+とZn2+の供給不足
に起因して高まつた界面PHが、メツキ皮膜中の
Ni含有率とZn（OH）2共析量とを高めた結果によ
るものであると理解できる。この考えに基づき本
願発明者等は、界面PHの上昇を抑制することが皮
膜加工性の低下を防止する基本であると考え、メ
ツキ浴のPH、メツキ浴と鋼板との相対速度、メツ
キ浴中のZn2+／（Zn2+＋Ni2+）をコントロールす
ることにより、メツキ皮膜の加工性低下を防止
し、健全な加工性を確保する方を見出した。
第１図から第４図に、次の条件でNi−Zn合金
電気メツキを行ない、高電流密度によりメツキを
行なつた場合のメツキ皮膜の加工性に、メツキ浴
のPH、メツキ浴と鋼板との相対速度、メツキ浴中
のNi2+／（Zn2+＋Ni2+）が及ぼす影響を示す。各
図中、〇印はメツキ皮膜の剥離が全くないか、ほ
とんどないことを示し、●印はメツキ皮膜の剥離
があることを示す。
条 件
硫酸亜鉛＋硫酸ニツケル：500ｇ/、
無水硫酸ナトリウム：60ｇ/、
Ni2+／（Zn2+＋Ni2+）：0.55、0.60、0.65、0.70、
メツキ浴温度：50℃、
電流密度：50A/dm2、
メツキ量：20ｇ/m2。
第１図から第４図から明らかなように、(1) メ
ツキ浴のPHの低下、(2) メツキ浴と鋼板との相対
速度の増加、(3) Zn2+／（Zn2+＋Ni2+）＝１−
Ni2+／（Zn2+＋Ni2+）の増加がメツキ皮膜の加工
性の低下防止に寄与するように作用する他、これ
ら(1)から(3)の要因が単独ではなく相互に関連しな
がら加工性に影響を及ぼしていることがわかる。
そこで、本願発明者等は、上記(1)から(3)の要因
を関連づけ、加工性の良、不良の境界条件とな
る、次の如き実験式を得た。
PHL＝0.85υ＋6.0（Ｚｎ２＋／Ｚｎ２＋＋Ｎｉ２＋−0.
1）
但し、
PHL：メツキ浴PHの上限値、
υ：メツキ浴と鋼板との相対速度（m/S）、
Zn2+：Zn2+濃度（ｇ/）、
Ni2+：Ni2+濃度（ｇ/）。
すなわち、上式を満足するPHのメツキ浴でメツ
キを行なえば、加工性の良好なメツキ皮膜が得ら
れる。
界面PHに及ぼすZn2+の影響を更に詳しく調べる
ために、Ni2+／（Zn2+＋Ni2+）＝0.65一定とし、
Zn2+濃度を変えてメツキ皮膜の加工性について調
べた。この結果を第３表に示す。[Table] In the following explanation, the workability of the plating film was tested and evaluated using the above method. As is clear from Table 1, the plating current density is
It can be seen that when it exceeds 30 A/dm 2 , the workability of the plating film decreases. This is considered to be due to the following reasons. That is, (1) Generally, the deformability of intermetallic compounds is smaller than that of pure metals, and therefore their workability is poor.
According to the phase diagram, the γ phase of Ni-Zn alloy is
The Ni content ranges from 13.5% to about 20%, and as a stoichiometric intermetallic compound, the Ni content is 17.6%.
% Ni 5 Zn 21 is shown to be present.
Since vacancies exist in the crystal lattice of Ni 5 Zn 21 when the Ni content is 17.6% or less, it is assumed that metal atoms can move to some extent during processing. From this, among the γ phases, those with a low Ni content are relatively easy to process, but as the Ni content increases, the processability decreases and peeling of the plating film occurs. (2) As will be described later, when a high current density is applied, the PH of the plating bath at the interface between the iron base (steel plate) and the plating bath, that is, the interface PH increases. The interface PH is
5.1 or higher, Zn(OH) 2 is generated, so Zn
(OH) 2 may eutectoid. Zn(OH) 2 precipitated at the interface blocks the metallic bond between the steel base and the Ni-Zn alloy, so when the coverage rate of the steel base surface with Zn(OH) 2 increases, the bond between the steel base and the plating film increases. Power weakens. Peeling occurs at interfaces with weak bonding strength when processing forces are applied. The Ni content of the plating film in Ni-Zn alloy electrodeposition increases as the pH of the plating bath increases, and it is thought that the eutectoid of Zn(OH) 2 is also promoted. This occurs at the interface between the steel plate and the plating bath, where the Ni content and Zn(OH) 2
It is the pH of the interface that determines the amount of eutectoid. interface
The pH is determined by the balance between the supply of H + from outside the diffusion layer of the plating bath and the generation of hydrogen gas. The supply of H + is a matter of mass transfer, and if the diffusion layer is made thinner by increasing the relative velocity between the cathode (steel plate) and the plating bath, the supply of H + becomes easier and the interface PH tends to decrease. Furthermore, according to the research of the present inventors, Ni
- When Zn alloy plating is performed, preferential precipitation occurs.
The supply of Zn 2+ to the cathode is insufficient, and the cathode reaction corresponding to the shortage becomes a hydrogen gas generating reaction, and the interfacial PH increases. From the above, the result in Table 1 that the workability of the plating film decreases with an increase in current density is due to the insufficient supply of H + and Zn 2+ from the bulk side of the plating bath to the interface. The interface PH in the plating film
This can be understood to be the result of increasing the Ni content and the amount of Zn(OH) 2 eutectoid. Based on this idea, the inventors of the present application believe that suppressing the increase in the interface PH is the basis for preventing a decrease in film workability, and the PH of the plating bath, the relative speed between the plating bath and the steel plate, By controlling Zn 2+ /(Zn 2+ + Ni 2+ ), we have found a way to prevent the deterioration of workability of the plating film and ensure healthy workability. Figures 1 to 4 show the workability of the plating film when electroplating Ni-Zn alloy under the following conditions and plating with high current density, the pH of the plating bath, and the relationship between the plating bath and the steel plate. The influence of Ni 2+ /(Zn 2+ + Ni 2+ ) in the plating bath is shown. In each figure, the ○ mark indicates that there is no or almost no peeling of the plating film, and the ● mark indicates that there is peeling of the plating film. Conditions Zinc sulfate + nickel sulfate: 500g/, anhydrous sodium sulfate: 60g/, Ni 2+ / (Zn 2+ + Ni 2+ ): 0.55, 0.60, 0.65, 0.70, plating bath temperature: 50℃, current density: 50A /dm 2 , plating amount: 20g/m 2 . As is clear from Figures 1 to 4, (1) a decrease in the pH of the plating bath, (2) an increase in the relative speed between the plating bath and the steel plate, and (3) Zn 2+ / (Zn 2+ + Ni 2 + )=1−
In addition to the increase in Ni 2+ /(Zn 2+ + Ni 2+ ) contributing to preventing the deterioration of workability of the plating film, these factors (1) to (3) are not independent but are interrelated. However, it can be seen that the processability is affected. Therefore, the inventors of the present application related the factors (1) to (3) above and obtained the following experimental formula, which serves as a boundary condition between good and poor workability. PH L =0.85υ+6.0 (Zn 2+ /Zn 2+ +Ni 2+ -0.
1) However, PH L : Upper limit value of plating bath PH, υ: Relative speed between plating bath and steel plate (m/S), Zn 2+ : Zn 2+ concentration (g/), Ni 2+ : Ni 2+ Concentration (g/). That is, if plating is performed in a plating bath with a pH that satisfies the above formula, a plating film with good workability can be obtained. In order to investigate the influence of Zn 2+ on the interface PH in more detail, Ni 2+ / (Zn 2+ + Ni 2+ ) = 0.65 constant,
The workability of the plating film was investigated by changing the Zn 2+ concentration. The results are shown in Table 3.
【表】
前述したように、界面PHに及ぼすZn2+の影響
は、カソード界面へのZn2+の供給不足によつつて
起こるのであるから、PHLにはZn2+濃度も関係す
ると考えられるが、第３表に見られるようにZn2+
濃度が低いときにPHがPHLより小さいとメツキ皮
膜の加工性が確保されない。従つて、前述したPH
Lを示す式はZn2+濃度が一定濃度以上で成立する
ことが明らかであり、実験によりZn2+が20ｇ/
以上でPHLの式が成立することが判明した。
以上の説明から明らかなように、加工性に優れ
たNi−Zn合金電気メツキ皮膜は、メツキ浴のPH
がPHL以下であり、かつZn2+が20ｇ/以上のメツ
キ浴から得られることがわかるが、加工性に加え
て優れた耐食性が得られてはじめて、Ni−Zn合
金電気メツキの優れた特性が保証される。
Ni−Zn合金電気メツキ鋼板の耐食性は、メツ
キ皮膜中のNi含有量によつて決定されることは
周知であるが、本願発明者等の研究によれば、30
A/dm2以上の電流密度でメツキしたNi−Zn合金電
気メツキ鋼板も、Ni含有率が６〜16％の範囲で
良好な耐食性を示し、特に、10〜14％の範囲では
きわめて優れた耐食性を示すことが明らかとなつ
た。Ni含有率が10〜14％のNi−Zn合金電気メツ
キ皮膜は、本願発明者等の研究によれば、Ni2+／
（Zn2+＋Ni2+）が0.55以上、0.90以下のZn2+、Ni2+
を含むメツキ浴から得られることがわかつた。
第４表に、耐食性と加工性を同時に評価した結
果を示す。耐食性は未塗装のNi−Zn合金電気メ
ツキ鋼板を、JIS Ｚ 2371に規定されている塩水
噴霧試験でテストし、赤錆発生時間で評価した。
評価基準を第５表に示す。[Table] As mentioned above, the influence of Zn 2+ on the interfacial PH is caused by the insufficient supply of Zn 2+ to the cathode interface, so it is thought that the Zn 2+ concentration is also related to the PH L. However, as seen in Table 3, Zn 2+
If the PH is lower than PH L when the concentration is low, the workability of the plating film cannot be ensured. Therefore, the aforementioned PH
It is clear that the formula for L holds true when the Zn 2+ concentration is above a certain level, and experiments show that Zn 2+ is 20g/
From the above, it was found that the formula for PH L holds true. As is clear from the above explanation, the Ni-Zn alloy electroplated film, which has excellent workability, has a PH of the plating bath.
is less than PH L and Zn 2+ is more than 20 g/L, but the excellent properties of Ni-Zn alloy electroplating cannot be achieved until excellent corrosion resistance is obtained in addition to workability. is guaranteed. It is well known that the corrosion resistance of Ni-Zn alloy electroplated steel sheets is determined by the Ni content in the plating film, but according to research by the present inventors, 30%
Ni-Zn alloy electroplated steel sheets plated at a current density of A/dm 2 or more also show good corrosion resistance in the Ni content range of 6 to 16%, and especially excellent corrosion resistance in the range of 10 to 14%. It has become clear that this shows that According to research by the present inventors, a Ni-Zn alloy electroplated film with a Ni content of 10 to 14% has a Ni 2+ /
(Zn 2+ + Ni 2+ ) is 0.55 or more and 0.90 or less Zn 2+ , Ni 2+
It was found that it can be obtained from a metsuki bath containing . Table 4 shows the results of simultaneous evaluation of corrosion resistance and workability. Corrosion resistance was evaluated by testing unpainted Ni-Zn alloy electroplated steel sheets using a salt spray test specified in JIS Z 2371, and determining the time it took for red rust to develop.
The evaluation criteria are shown in Table 5.
【表】【table】
【表】
第４表から次のことがわかる。すなわち、
(1) メツキ皮膜中のNi含有率が10％未満では、
加工性は良好であるが耐食性が低下する。
(2) メツキ皮膜中のNi含有率が14％以上になる
と、加工性、耐食性ともに低下する傾向を示
す。
(3) メツキ皮膜中のNi含有率が10％以上で、加
工性に優れたメツキ皮膜の得られる条件でメツ
キを行なうことにより、耐食性と加工性に優れ
たNi−Zn合金電気メツキ皮膜が得られる。
(4) メツキ浴のPHがPHL以下であれば、加工性は
良好である。
以上(1)から(4)の事項を整理すると、耐食性、加
工性ともに優れたNi−Zn合金電気メツキ鋼板
は、以下の条件(イ)から(ハ)で高電流密度を適用しな
がら製造可能である。
(イ) メツキ浴のPHが次式で示されるPHLより低い
こと。
PHL＝0.85υ＋6.0（Ｚｎ２＋／Ｚｎ２＋＋Ｎｉ２＋−
0.1）
(ロ) メツキ浴中のZn2+濃度が20ｇ/以上である
こと。
(ハ) Ni2+／（Zn2+＋Ni2+）が0.55〜0.90の範囲にあ
ること。
次に、この発明の実施例について説明する。
実施例 １
電解脱脂と酸洗の前処理を行なつた後、次のメ
ツキ条件で鋼板にNi−Zn合金電気メツキを行な
い、その後、メツキ鋼板の耐食性と加工性につい
て調べた。メツキに際して鋼板とメツキ浴との相
対速度は、メツキ浴を流動させることによつて調
整した。
(1) メツキ浴の組成
Ni2+／（Zn2+＋Ni2+）：0.65
硫酸亜鉛：175ｇ/、
硫酸ニツケル：325ｇ/、
無水硫酸ナトリウム：60ｇ/、
(2) メツキ浴のPH：2.0、
(3) 相対速度：０〜1.5m/S、
(4) メツキ浴の温度：50℃、
(5) 電流密度：50A/dm2。
この結果を第６表に示す。
第６表から明らかなように、メツキ浴のPHがPH
L以下のNo.4〜６では、メツキ量が20ｇ/m2、30
ｇ/m2の何れの場合においても優れた耐食性と加
工性を具備した、Ni−Zn合金電気メツキ皮膜を
有する鋼板を製造することができることがわか
る。[Table] The following can be seen from Table 4. That is, (1) If the Ni content in the plating film is less than 10%,
Workability is good, but corrosion resistance is reduced. (2) When the Ni content in the plating film exceeds 14%, both workability and corrosion resistance tend to decrease. (3) By performing plating under conditions where the Ni content in the plating film is 10% or more and a plating film with excellent workability can be obtained, a Ni-Zn alloy electroplated film with excellent corrosion resistance and workability can be obtained. It will be done. (4) If the PH of the plating bath is below PH L , the workability is good. Summarizing matters (1) to (4) above, Ni-Zn alloy electroplated steel sheets with excellent corrosion resistance and workability can be manufactured under the following conditions (a) to (c) while applying high current density. It is. (a) The PH of the plating bath is lower than the PH L shown by the following formula. PH L =0.85υ+6.0(Zn 2+ /Zn 2+ +Ni 2+ −
0.1) (b) The Zn 2+ concentration in the plating bath shall be 20g/or more. (c) Ni 2+ /(Zn 2+ + Ni 2+ ) is in the range of 0.55 to 0.90. Next, embodiments of the invention will be described. Example 1 After pretreatment of electrolytic degreasing and pickling, a steel plate was electroplated with a Ni-Zn alloy under the following plating conditions, and then the corrosion resistance and workability of the plated steel plate were investigated. During plating, the relative speed between the steel plate and the plating bath was adjusted by making the plating bath flow. (1) Composition of plating bath Ni 2+ / (Zn 2+ + Ni 2+ ): 0.65 Zinc sulfate: 175 g/, Nickel sulfate: 325 g/, Anhydrous sodium sulfate: 60 g/, (2) PH of plating bath: 2.0, (3) Relative speed: 0 to 1.5 m/S, (4) Temperature of plating bath: 50°C, (5) Current density: 50 A/dm 2 . The results are shown in Table 6. As is clear from Table 6, the PH of the plating bath is PH
For No. 4 to 6 below L , the plating amount is 20g/m 2 , 30
It can be seen that a steel plate having a Ni--Zn alloy electroplated film having excellent corrosion resistance and workability can be produced in any case of g/m 2 .
【表】
実施例 ２
硫酸亜鉛150ｇ/、硫酸ニツケル350ｇ/、無
水硫酸ナトリウム60ｇ/、酢酸ナトリウム27ｇ/
（PH緩衝剤）から成るメツキ浴を硫酸にてPH＝
1.8と2.4にそれぞれ調整後、次の条件にて電気メ
ツキした鋼板の耐食性と加工性を調べた。
(1) メツキ電流密度：10〜70A/dm2、
相対速度：1.0m/S、
メツキ浴温度：50℃。
この結果を第７表に示す。[Table] Example 2 Zinc sulfate 150g/, nickel sulfate 350g/, anhydrous sodium sulfate 60g/, sodium acetate 27g/
(PH buffer) with sulfuric acid
After adjusting to 1.8 and 2.4, respectively, the corrosion resistance and workability of the electroplated steel sheets were investigated under the following conditions. (1) Plating current density: 10-70A/dm 2 , relative speed: 1.0m/S, plating bath temperature: 50℃. The results are shown in Table 7.
【表】【table】
【表】
第７表から明らかなように、PHLより高い値の
PH＝2.4のメツキ浴を用いると、電流密度が10A/
ｄm2のような低い電流密度では耐食性、加工性共
に良好なメツキ皮膜を有する鋼板が得られるが、
この性能は電流密度が30A/dm2以上となると失わ
れる。特に、50A/dm2以上の高電流密度で加工性
が著しく低下する。一方PHLより低い値のPH＝1.8
のメツキ浴では70A/dm2の高電流密度まで耐食
性、加工性共に良好なメツキ皮膜を有する鋼板を
製造することができることがわかる。また、PHが
1.8のメツキ浴と2.4のメツキ浴との場合を比較す
ると、50A/dm2以上の電流密度で両条件下で製造
したメツキ材の性能の差が顕著に現われている。
以上説明したように、この発明によれば、耐食
性、加工性共に優れたNi−Zn合金電気メツキ鋼
板を高電流密度を適用して能率良く製造すること
ができるといつたきわめて有用な効果がもたらさ
れる。[Table] As is clear from Table 7, the value higher than PH L
When using a plating bath with pH=2.4, the current density is 10A/
At a low current density such as dm 2 , a steel plate with a plating film with good corrosion resistance and workability can be obtained, but
This performance is lost when the current density exceeds 30 A/dm 2 . In particular, workability is significantly reduced at high current densities of 50 A/dm 2 or higher. On the other hand, PH lower than PH L = 1.8
It can be seen that the plating bath can produce a steel plate with a plating film with good corrosion resistance and workability up to a high current density of 70 A/dm 2 . Also, the PH
Comparing the case of plating bath of 1.8 and plating bath of 2.4, the difference in performance of the plating materials produced under both conditions at a current density of 50 A/dm 2 or higher is noticeable. As explained above, the present invention brings about extremely useful effects such as being able to efficiently manufacture Ni-Zn alloy electroplated steel sheets with excellent corrosion resistance and workability by applying high current density. It can be done.
第１図から第４図は、メツキ浴と鋼板との相対
速度とメツキ浴のPHとの関係を示す図である。
FIGS. 1 to 4 are diagrams showing the relationship between the relative speed between the plating bath and the steel plate and the pH of the plating bath.
Claims (1)
において、PHが次式で表わされるPHL以下で、 PHL＝0.85v＋6.0（Ｚｎ２＋／Ｚｎ２＋＋Ｎｉ２＋−0.1
） 但し、 ｖ：メツキ浴と鋼板との相対速度（m/S）。 Zn2+が20ｇ/以上で、しかも、Ni2+／（Zn2+
＋Ni2+）が0.55から0.90の範囲内であるメツキ浴
を使用して50A/dm2以上の高電流密度でメツキを
行なうことを特徴とする、加工性および耐食性に
優れたNi−Zn合金電気メツキ鋼板の製造方法。[Claims] 1. In the method of manufacturing a Ni-Zn alloy electroplated steel sheet, PH is less than or equal to PH L expressed by the following formula, PH L = 0.85v + 6.0 (Zn 2+ /Zn 2+ + Ni 2+ -0.1
) However, v: relative speed between the plating bath and the steel plate (m/S). Zn 2+ is 20g/ or more, and Ni 2+ / (Zn 2+
Ni-Zn alloy electric with excellent workability and corrosion resistance, characterized by plating at a high current density of 50 A/dm 2 or more using a plating bath with +Ni 2+ ) in the range of 0.55 to 0.90. Method for producing plated steel sheets.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8726682A JPS58204195A (en) | 1982-05-25 | 1982-05-25 | Manufacture of steel plate electroplated with ni-zn alloy and provided with superior workability and corrosion resistance |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8726682A JPS58204195A (en) | 1982-05-25 | 1982-05-25 | Manufacture of steel plate electroplated with ni-zn alloy and provided with superior workability and corrosion resistance |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS58204195A JPS58204195A (en) | 1983-11-28 |
| JPS6138274B2 true JPS6138274B2 (en) | 1986-08-28 |
Family
ID=13909959
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP8726682A Granted JPS58204195A (en) | 1982-05-25 | 1982-05-25 | Manufacture of steel plate electroplated with ni-zn alloy and provided with superior workability and corrosion resistance |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS58204195A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH01204865A (en) * | 1987-12-28 | 1989-08-17 | Ford Motor Co | Device for automobile dynamically determining road-surface friction |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS616290A (en) * | 1984-06-21 | 1986-01-11 | Kawasaki Steel Corp | Surface-treated steel sheet having high corrosion resistance and its production |
| JPS61133394A (en) * | 1984-12-01 | 1986-06-20 | Nisshin Steel Co Ltd | Method for plating zn-ni alloy with high electric current |
| JPH0814038B2 (en) * | 1988-07-20 | 1996-02-14 | 川崎製鉄株式会社 | Method for producing Zn-Ni alloy plated steel sheet |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS55110791A (en) * | 1979-02-15 | 1980-08-26 | Sumitomo Metal Ind Ltd | Preparation of plated steel plate with high corrosion resistance |
| JPS55152194A (en) * | 1979-05-12 | 1980-11-27 | Nippon Steel Corp | Production of steel strip plated by zinc-nickel alloy |
| US4249999A (en) * | 1979-03-30 | 1981-02-10 | Sumitomo Metal Industries, Ltd. | Electrolytic zinc-nickel alloy plating |
| JPS5839236A (en) * | 1981-08-31 | 1983-03-07 | Toshiba Corp | Winding of rotary electric machine |
| JPS58197292A (en) * | 1982-05-14 | 1983-11-16 | Nippon Steel Corp | Production of steel plate plated with gamma zinc-nickel alloy in high efficiency |
-
1982
- 1982-05-25 JP JP8726682A patent/JPS58204195A/en active Granted
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS55110791A (en) * | 1979-02-15 | 1980-08-26 | Sumitomo Metal Ind Ltd | Preparation of plated steel plate with high corrosion resistance |
| US4249999A (en) * | 1979-03-30 | 1981-02-10 | Sumitomo Metal Industries, Ltd. | Electrolytic zinc-nickel alloy plating |
| JPS55152194A (en) * | 1979-05-12 | 1980-11-27 | Nippon Steel Corp | Production of steel strip plated by zinc-nickel alloy |
| JPS5839236A (en) * | 1981-08-31 | 1983-03-07 | Toshiba Corp | Winding of rotary electric machine |
| JPS58197292A (en) * | 1982-05-14 | 1983-11-16 | Nippon Steel Corp | Production of steel plate plated with gamma zinc-nickel alloy in high efficiency |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH01204865A (en) * | 1987-12-28 | 1989-08-17 | Ford Motor Co | Device for automobile dynamically determining road-surface friction |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS58204195A (en) | 1983-11-28 |
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