JPH0563558B2 - - Google Patents
Info
- Publication number
- JPH0563558B2 JPH0563558B2 JP23017886A JP23017886A JPH0563558B2 JP H0563558 B2 JPH0563558 B2 JP H0563558B2 JP 23017886 A JP23017886 A JP 23017886A JP 23017886 A JP23017886 A JP 23017886A JP H0563558 B2 JPH0563558 B2 JP H0563558B2
- Authority
- JP
- Japan
- Prior art keywords
- plating
- steel plate
- pickling
- film
- nickel alloy
- 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 - Lifetime
Links
- 238000007747 plating Methods 0.000 claims description 93
- 229910000831 Steel Inorganic materials 0.000 claims description 64
- 239000010959 steel Substances 0.000 claims description 64
- 238000005554 pickling Methods 0.000 claims description 34
- 229910000990 Ni alloy Inorganic materials 0.000 claims description 28
- QELJHCBNGDEXLD-UHFFFAOYSA-N nickel zinc Chemical compound [Ni].[Zn] QELJHCBNGDEXLD-UHFFFAOYSA-N 0.000 claims description 27
- 239000011248 coating agent Substances 0.000 claims description 18
- 238000000576 coating method Methods 0.000 claims description 18
- 238000000034 method Methods 0.000 claims description 14
- 238000004519 manufacturing process Methods 0.000 claims description 11
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 10
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 24
- 230000007797 corrosion Effects 0.000 description 12
- 238000005260 corrosion Methods 0.000 description 12
- 229910052759 nickel Inorganic materials 0.000 description 12
- 239000000203 mixture Substances 0.000 description 10
- 238000010422 painting Methods 0.000 description 10
- 238000005516 engineering process Methods 0.000 description 9
- 229910003460 diamond Inorganic materials 0.000 description 5
- 239000010432 diamond Substances 0.000 description 5
- 239000003973 paint Substances 0.000 description 5
- 230000006866 deterioration Effects 0.000 description 4
- 238000007654 immersion Methods 0.000 description 4
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- 239000011701 zinc Substances 0.000 description 2
- 241000080590 Niso Species 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 239000002390 adhesive tape Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 125000002091 cationic group Chemical group 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000013065 commercial product Substances 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 239000003599 detergent Substances 0.000 description 1
- 238000004070 electrodeposition Methods 0.000 description 1
- 238000005868 electrolysis reaction Methods 0.000 description 1
- 238000009713 electroplating Methods 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000010297 mechanical methods and process Methods 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- 235000021110 pickles Nutrition 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 239000004575 stone Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000003746 surface roughness Effects 0.000 description 1
- 230000004580 weight loss Effects 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
- 239000011787 zinc oxide Substances 0.000 description 1
Landscapes
- Electroplating And Plating Baths Therefor (AREA)
- Electroplating Methods And Accessories (AREA)
Description
〔発明の技術分野〕
この発明は、めつき皮膜が塗装後の低温におけ
る衝撃に対して塗膜と共に剥離することのない、
塗装後の低温衝撃密着性に優れためつき皮膜を有
する電気亜鉛−ニツケル合金めつき鋼板の製造方
法に関するものである。
〔従来技術とその問題点〕
苛酷な腐食環境下で使用される自動車用の耐食
材料として、各種の亜鉛系合金めつき鋼板が検討
され、開発されている。これらの中で、亜鉛−ニ
ツケル系合金めつき鋼板は、めつき皮膜が優れた
耐食性を示すため注目されている。しかし、亜鉛
−ニツケル系合金めつき皮膜は、硬くてもろいこ
と、および、内部応力が大であること等により、
実用に際してはいくつかの問題があつた。
例えば、軽度の加工でめつき皮膜に微細なクラ
ツクが無数に発生し、鋼素地からの赤錆がクラツ
ク部より短時間で発生する。このため、亜鉛−ニ
ツケル系合金めつき鋼板は、無加工の平板では優
れた耐食性を発輝するものの、加工を旋すと、加
工部の耐食性が著しく劣化し、平板の耐食性の半
分以下の耐食性になつてしまう。
そこで、例えば特開昭56−35790号、特開昭59
−200789号および特公昭61−439号等では、加工
による耐食性の劣化を改善する提案を行なつてい
る。これらの従来技術によれば加工による耐食性
の劣化を改善でき、亜鉛−ニツケル合金めつき鋼
板を無塗装で使用する場合には、それなりに有益
な技術であると考えられる。しかし、塗装して使
用する場合には、新な問題を生じることがわかつ
た。
すなわち、亜鉛−ニツケル合金めつき鋼板を塗
装して衝撃を与えると、塗膜がめつき皮膜と共に
剥離し、鋼素地が露出する。この問題は特に低温
で顕著であり、低温では、鋼素地の明らかな変形
を伴わないでも衝撃だけで、塗膜がめつき皮膜と
共に剥離する。例えば北米などの寒冷地で冬期に
自動車が走行したときに、撥ねて飛んで来た小石
によつて車体外板の塗膜がめつき皮膜と共に剥離
し、耐食性や外観を損うことを考えれば、この問
題の重要性が理解できる。
この問題を改善する技術としては、例えば特開
昭59−107095号が知られている。上記公報記載の
技術は、プレスなどの加工や塗装後の石はね等に
よつて衝撃を受けた際に、めつき皮膜に大きいク
ラツクが生じたり、めつき皮膜が剥離することの
ない、加工性、耐衝撃性に優れた亜鉛−ニツケル
合金めつき鋼板を目的としたものである。その特
徴は、鋼板の少なくとも片面に５ｇ／m2以上の亜
鉛−ニツケル合金めつき皮膜を有し、且つ、その
めつき皮膜のニツケル含有率は鋼板界面では7wt
％以下、皮膜表面では10〜16wt％で、鋼板界面
から皮膜表面に向かつて連続的に増加させたこと
にある。
しかし、上記公報記載の技術には、次のような
問題がある。
すなわち、めつき皮膜のニツケル含有率を連続
的に変えるには、(1)めつき浴中のニツケル濃度を
変えるめつき浴組成の変更、又は、(2)めつき電流
密度、撹拌条件等のめつき条件の変更が必要であ
る。鋼板の電気めつき設備は通常複数個のめつき
セルを有しており、めつきセルごとにめつき浴組
成、めつき条件を変更することは可能である。し
かし、めつきセルごとにめつき浴組成を変更する
ことは、めつきセルごとに循環系が必要であり、
循環系ごとにめつき浴組成を管理しなければなら
ない。このことは、同一めつき浴組成であれば循
環系は少なくとも１つでよく、従つてめつき浴組
成の管理は少なくとも１回で済むことを考えれ
ば、めつき浴組成の管理が非常に繁雑になること
が容易に判る。１方、めつきセルごとにめつき条
件を変更することは、めつき条件の管理の上で上
記と同様な問題を生じると共に、次のような生産
効率の低下の問題がある。
上記公報記載の第２図によれば、亜鉛−ニツケ
ル合金めつき皮膜のニツケル含有率が12〜14wt
％であれば100A／ｄm2のめつき電流密度で、そ
してニツケル含有率が7wt％であれば25A／ｄm2
のめつき電流密度でめつき可能であることが示さ
れている。上述したように、上記公報記載の技術
では、めつき皮膜のニツケル含有率は鋼板界面で
7wt％以下、皮膜表面で10〜16wt％であり、その
間で連続的に増加しているので、平均で約60A／
ｄm2のめつき電流密度でめつきすることになる。
通常の亜鉛−ニツケル合金めつきのニツケル含有
率は12〜14wt％であることを考えれば、通常の
亜鉛−ニツケル合金めつきでは、100A／ｄm2の
めつき電流密度でめつきできるはずであり、これ
と比較すると、上記公報記載の技術は生産効率が
著しく低い。
上記公報記載の技術には、以上の操業上の問題
に加えて、品質上の問題もいくつかある。
一般に、亜鉛−ニツケル合金めつきにおいて
は、めつき皮膜の耐食性が最も良好なのは、ニツ
ケル含有率が9wt％以上のγ単相からめつき皮膜
がなる場合である。上記公報記載の技術では、ニ
ツケル含有率は鋼板界面で7wt％以下であるか
ら、めつき皮膜中にニツケル含有率が9wt％以下
のめつき皮膜層が存在することになる。このよう
な低ニツケル含有率のめつき皮膜層では、γ相と
共に純Znのη相が析出して、耐食性を著しく低
下することが良く知られている。従つて、耐食性
の劣化という品質上の問題を生じる。また、めつ
き皮膜中のニツケル含有率が鋼板界面で少なく、
皮膜表面で多いことから、皮膜表面に比べて鋼板
界面が電位的に卑になる。このときも良く知られ
ているように、例えば塗装板で塗膜上からめつき
皮膜に傷が生じると、めつき皮膜は鋼板界面の卑
の部分から優先的に溶出するために、ブリスター
が生じ易くなり、結果的に耐食性を著しく損う。
以上の従来技術は、亜鉛−ニツケル合金めつき
鋼板製造の主たる技術のめつき技術の改善であ
り、めつき技術の変更は操業上および設備上重大
な影響を及ぼす。例えば、先に掲げた特公昭61−
439号のようにプレめつきを行なう技術では、プ
レめつき用の新なめつき浴組成やめつき条件の管
理が一層厳しく要求され、必要に応じてプレめつ
き用のめつきセルの新設等が必要になる。また、
上述したように、特開昭59−107095号の技術で
は、めつきセルごとにめつき条件の管理が必要で
あり、そのためにめつきセルごとにめつき電流を
連続的に増加するよう配分する設備等が必要にな
る。
〔発明の目的〕
この発明は、上述の現状に鑑み、めつき皮膜が
塗装後の低温における衝撃に対して塗膜と共に剥
離することのない、塗装後の低温衝撃密着性に優
れためつき皮膜を有する電気亜鉛−ニツケル合金
めつき鋼板を、めつき鋼板製造の主たる技術のめ
つき技術を変更することなく、容易に製造するこ
とができる方法を提供することを目的とするもの
である。
〔発明の概要〕
この発明は、鋼板を電気亜鉛−ニツケル合金め
つき処理するにあたり、前記めつきの処理前に、
前記鋼板の酸洗減量が400mg／m2以上となるよう
に、150〜300ｇ／の濃度の硫酸酸洗浴中に前記
鋼板を浸漬することにより前記鋼板を酸洗して、
前記鋼板表面の酸化物皮膜を除去すると共に、前
記鋼板の表面に微細な凹凸を形成して前記表面を
括性化させ、次いで、前記鋼板に対し、電気亜鉛
−ニツケル合金めつき処理を旋すことに特徴を有
するものである。
〔発明の構成〕
以下、この発明の、塗装後の低温衝撃密着性に
優れためつき皮膜を有する電気亜鉛−ニツケル合
金めつき鋼板の製造方法について詳述する。
本発明者等は、亜鉛−ニツケル合金めつき鋼板
におけるめつき皮膜の、塗装後の低温衝撃密着性
について検討を重ねた結果、亜鉛−ニツケル合金
めつき鋼板のめつき条件と共に、めつきの前処理
として行なう酸洗の条件も、塗装後の低温衝撃密
着性に重大な影響を与えていることを見い出し
た。
めつき鋼板の製造では、めつきの処理前に、前
処理として酸洗が行なわれている。この酸洗は、
従来は、鋼板表面の酸化物皮膜を除去を目的とし
ており、鋼板表面とめつき皮膜との間に酸化物皮
膜が介在することによるめつき皮膜の密着性の劣
化を防止するために行なわれるものである。
この発明では、酸洗を単に酸化物皮膜の除去に
留めず、酸洗剤の濃度、酸洗浴の温度等の酸洗の
条件を強化することによつて、鋼板表面の粗さを
大とすると共に鋼板表面を括性化するという新た
な意義を酸洗に持たせ、これによつて、亜鉛−ニ
ツケル合金めつき鋼板の塗装後の低温衝撃密着性
を改善するものである。すなわち、この発明で
は、亜鉛−ニツケル合金めつき鋼板製造における
前処理である酸洗の条件を強化して、酸洗減量を
多くした酸洗を行ない、これによつて鋼板表面の
粗さを大にしたのちに、所定の電気亜鉛−ニツケ
ル合金めつきを行なうものである。
酸洗減量は、鋼板表面の酸化物皮膜の除去を目
的とした従来では、通常、多くても200mg／m2程
度であるが、この発明では、これを400mg／m2以
上とする。酸洗減量の増加によりめつき皮膜の塗
装後の低温衝撃密着性が向上する理由は詳しくは
不明であるが、機械的に表面粗さを大にする方法
では効果がないことから考えて、酸洗減量を増加
した酸洗によれば、鋼板表面に非常に微細な凹凸
が形成されて、鋼板単位面積当りの表面積が増加
するために、鋼板単位面積当りのめつき皮膜の密
着力を増加させられることが一因になつているこ
とによるものと思われる。酸洗減量が400mg／m2
未満では、鋼板単位面積当りの表面積の増加が少
なく、めつき皮膜の塗装後の低温衝撃密着性が充
分に得られない。
酸洗減量が400mg／m2以上になるように鋼板を
酸洗するためには、150〜300ｇ／（8.15〜16.3
容量％）の濃度の硫酸酸洗浴中に、所定時間鋼板
を浸漬することが必要である。
酸洗浴中の硫酸濃度が150ｇ／未満では、酸
洗減量が400mg／m2以上になるように鋼板を酸洗
することができない。一方、酸洗浴中の硫酸濃度
が300ｇ／を超えると、酸洗浴中へのFeの溶解
量が増大する結果、酸洗浴が劣化してその更新頻
度が増大し、不経済になる。
〔実施例〕
この発明を実施例により更に詳述する。
めつきの前処理として、この発明の範囲内の酸
洗減量で酸洗を鋼板に行ない、次いで、鋼板に所
定の電気亜鉛−ニツケル合金めつきを行なつて、
本発明めつき鋼板No.１〜６を製造した。そして、
本発明めつき鋼板No.１〜６に３コート塗装を行な
つたのち、低温におけるダイヤモンドシヨツト試
験を行ない、めつき皮膜の塗装後の低温衝撃密着
性を調べた。比較のために、この発明の範囲外の
酸洗減量で酸洗を鋼板に行ない、次いで、鋼板に
所定の電気亜鉛−ニツケル合金めつきを行なつ
て、比較めつき鋼板No.１〜２を製造し、同様に、
３コート塗装を行ない、低温におけるダイヤモン
ドシヨツト試験を行なつた。
酸洗の条件は次の墜りである。
本発明No.１〜6.
浸漬酸洗浴：H2SO4150〜300ｇ／、
浴温 ：35〜60℃、
浸漬時間 ：６〜30秒．
比較No.1.
浸漬酸洗浴：H2SO4 80ｇ／、
浴温 ：25℃、
浸漬時間 ：６秒．
比較No.2.
電解酸洗浴：HCl10ｇ／、
浴温 ：20℃、
電解時間 ：1.2秒、
電流密度 ：10A／ｄm2．
めつき浴組成およびめつき条件は次の通りであ
る。
めつき浴組成．
ZnSO4・7H2O：150ｇ／、
NiSO4・7H2O：350ｇ／、
Na2SO4 ：55ｇ／．
めつき条件．
めつき浴PH：1.3、
めつき浴温：50℃、
電流密度 ：50A／ｄm2、
めつき量 ：20ｇ／m2．
３コート塗装の前処理の化成処理は、通常自動
車メーカーで使用されているデイツプタイプのリ
ン酸塩処理液（日本パーカーライジング社製の市
販品）により標準条件で行なつた。
３コート塗装は、次の通り行なつた。
下塗り．
カチオンタイプのED塗装（電着塗装）で、日
本ペイント社製の市販ED塗料を用いて、20μmの
標準塗装および焼付を行なつた。
中塗り．
関西ペイント社製の市販中塗り塗料を用いて、
35μmの標準中塗り塗装および焼付を行なつた。
上塗り．
関西ペイント社製の市販中塗り塗料を用いて、
35μmの標準上塗り塗装および焼付を行なつた。
低温におけるダイヤモンドシヨツト試験は、次
の通り行なつた。３コート塗装した試料をマイナ
ス20℃に冷却して、工業用ダイヤモンドを170
Km／hrの速度でサンプルの10ケ所にシヨツトし、
シヨツトした箇所に対して粘着テープによるテー
ピングを行なつて、塗膜およびめつき皮膜の剥離
の有無を調べた。
ダイヤモンドシヨツト試験結果を、酸洗減量等
と共に、第１表に示す。
[Technical Field of the Invention] The present invention provides a method that prevents the plating film from peeling off together with the coating film due to impact at low temperatures after painting.
The present invention relates to a method for manufacturing an electrolytic zinc-nickel alloy plated steel sheet having a tacky coating with excellent low-temperature impact adhesion after coating. [Prior art and its problems] Various zinc-based alloy coated steel sheets have been studied and developed as corrosion-resistant materials for automobiles used in severe corrosive environments. Among these, zinc-nickel alloy plated steel sheets are attracting attention because the plating film exhibits excellent corrosion resistance. However, the zinc-nickel alloy plating film is hard and brittle, and has large internal stress, so
There were some problems in practical use. For example, light machining can cause numerous fine cracks to occur in the plating film, and red rust from the steel base will occur in a shorter time than the cracks. For this reason, zinc-nickel alloy coated steel sheets exhibit excellent corrosion resistance when used as unprocessed flat plates, but when turned, the corrosion resistance of the processed areas deteriorates significantly, resulting in corrosion resistance that is less than half of that of flat plates. I'm getting used to it. Therefore, for example, JP-A-56-35790, JP-A-59
-200789 and Japanese Patent Publication No. 61-439, etc., propose ways to improve the deterioration of corrosion resistance due to processing. These conventional techniques can improve the deterioration of corrosion resistance due to processing, and are considered to be useful techniques in their own way when zinc-nickel alloy plated steel sheets are used without coating. However, it was found that when used after painting, a new problem arises. That is, when a zinc-nickel alloy plated steel sheet is coated and subjected to impact, the coating peels off together with the plating film, exposing the steel base. This problem is particularly noticeable at low temperatures; at low temperatures, the coating film will peel off along with the plating film due to impact alone, even without obvious deformation of the steel base. For example, when a car is driven in the winter in a cold region such as North America, the coating on the outer panel of the car body is peeled off along with the plating film caused by flying pebbles, which impairs corrosion resistance and appearance. I can understand the importance of this issue. As a technique for improving this problem, for example, Japanese Patent Laid-Open No. 107095/1984 is known. The technology described in the above publication is a processing method that does not cause large cracks in the plating film or peeling of the plating film when subjected to processing such as pressing or impact from stone splashes after painting. The objective is to produce a zinc-nickel alloy plated steel sheet with excellent strength and impact resistance. Its characteristics are that it has a zinc-nickel alloy plating film of 5 g/m 2 or more on at least one side of the steel plate, and the nickel content of the plating film is 7wt at the steel plate interface.
% or less, on the film surface it was 10 to 16 wt%, and it increased continuously from the steel plate interface to the film surface. However, the technique described in the above publication has the following problems. In other words, in order to continuously change the nickel content of the plating film, (1) changing the plating bath composition to change the nickel concentration in the plating bath, or (2) changing the plating current density, stirring conditions, etc. It is necessary to change the plating conditions. The electroplating equipment for steel sheets usually has a plurality of plating cells, and it is possible to change the plating bath composition and plating conditions for each plating cell. However, changing the plating bath composition for each plating cell requires a circulation system for each plating cell.
The plating bath composition must be controlled for each circulation system. This means that if the plating bath composition is the same, at least one circulation system is required, and therefore the plating bath composition only needs to be managed at least once, making the management of the plating bath composition extremely complicated. It is easy to see that. On the other hand, changing the plating conditions for each plating cell causes problems similar to those described above in terms of managing the plating conditions, as well as the following problem of reduced production efficiency. According to Figure 2 described in the above publication, the nickel content of the zinc-nickel alloy plating film is 12 to 14 wt.
%, the plating current density is 100A/ dm2 , and if the nickel content is 7wt%, it is 25A/ dm2.
It has been shown that plating is possible at the plating current density. As mentioned above, in the technology described in the above publication, the nickel content of the plating film is low at the steel plate interface.
7wt% or less, 10 to 16wt% on the film surface, and increases continuously between them, so the average current is about 60A/
Plating is carried out at a plating current density of dm 2 .
Considering that the nickel content of normal zinc-nickel alloy plating is 12 to 14 wt%, it should be possible to plate with a plating current density of 100 A/dm 2 in normal zinc-nickel alloy plating. Compared to this, the technology described in the above publication has significantly lower production efficiency. In addition to the operational problems mentioned above, the technology described in the above publication also has some quality problems. Generally, in zinc-nickel alloy plating, the best corrosion resistance of the plating film is when the plating film is made of a single γ phase with a nickel content of 9 wt % or more. In the technique described in the above publication, the nickel content is 7 wt% or less at the steel plate interface, so a plating film layer with a nickel content of 9 wt% or less is present in the plating film. It is well known that in such a plating film layer with a low nickel content, the η phase of pure Zn precipitates together with the γ phase, resulting in a significant decrease in corrosion resistance. Therefore, a quality problem arises in that corrosion resistance deteriorates. In addition, the nickel content in the plating film is low at the steel plate interface,
Since it is abundant on the film surface, the potential of the steel plate interface is less noble than that of the film surface. As is well known in this case, for example, when a scratch occurs on the plating film on a painted plate, blisters are likely to occur because the plating film is preferentially eluted from the base part of the steel plate interface. As a result, corrosion resistance is significantly impaired. The above-mentioned conventional technology is an improvement of the plating technology, which is the main technology for manufacturing zinc-nickel alloy plated steel sheets, and changes in the plating technology have a significant impact on operations and equipment. For example, the above-mentioned special public service in Showa 61-
In the technology of pre-plating as in No. 439, new plating bath composition for pre-plating and control of plating conditions are more strictly required, and if necessary, new plating cells for pre-plating may be installed. It becomes necessary. Also,
As mentioned above, in the technique of JP-A-59-107095, it is necessary to manage the plating conditions for each plating cell, and for this purpose, the plating current is distributed to each plating cell so that it increases continuously. Equipment etc. will be required. [Objective of the Invention] In view of the above-mentioned current situation, the present invention provides a plating film that has excellent low-temperature impact adhesion after painting and which does not peel off together with the coating film due to impact at low temperatures after painting. It is an object of the present invention to provide a method for easily manufacturing an electrolytic zinc-nickel alloy plated steel sheet without changing the plating technique, which is the main technique for manufacturing the plated steel sheet. [Summary of the Invention] The present invention provides a method for electrolytic zinc-nickel alloy plating of a steel plate, prior to the plating process.
Pickling the steel plate by immersing it in a sulfuric acid pickling bath with a concentration of 150 to 300 g/m2 so that the pickling loss of the steel plate is 400 mg/m2 or more ,
At the same time as removing the oxide film on the surface of the steel sheet, forming fine irregularities on the surface of the steel sheet to make the surface rough, and then subjecting the steel sheet to electrolytic zinc-nickel alloy plating treatment. It has particular characteristics. [Structure of the Invention] Hereinafter, the method of manufacturing an electrolytic zinc-nickel alloy plated steel sheet having a taming film with excellent low-temperature impact adhesion after coating according to the present invention will be described in detail. As a result of repeated studies on the low-temperature impact adhesion of the plating film on zinc-nickel alloy coated steel sheets, the present inventors have determined the plating conditions for zinc-nickel alloy coated steel sheets as well as the plating pretreatment. It has been found that the conditions of pickling performed as follows also have a significant effect on the low-temperature impact adhesion after painting. In the production of plated steel sheets, pickling is performed as a pretreatment before plating. This pickling is
Conventionally, the purpose was to remove the oxide film on the surface of the steel sheet, and it was carried out to prevent the deterioration of the adhesion of the plating film due to the presence of an oxide film between the steel sheet surface and the plating film. be. In this invention, pickling is not limited to simply removing the oxide film, but by increasing the pickling conditions such as the concentration of the pickling detergent and the temperature of the pickling bath, the roughness of the steel sheet surface is increased. Pickling has a new meaning of curing the surface of a steel sheet, thereby improving the low-temperature impact adhesion of zinc-nickel alloy plated steel sheets after coating. That is, in this invention, the conditions of pickling, which is a pretreatment in the production of zinc-nickel alloy coated steel sheets, are strengthened to perform pickling with a large pickling weight, thereby greatly increasing the roughness of the steel sheet surface. After that, a predetermined electrolytic zinc-nickel alloy plating is performed. In the conventional method for removing an oxide film on the surface of a steel sheet, the loss in pickling is usually about 200 mg/m 2 at most, but in the present invention, this is set to 400 mg/m 2 or more. The reason why the low-temperature impact adhesion after coating of the plating film improves due to the increase in the amount of acid washing is unknown, but considering that mechanical methods of increasing surface roughness are ineffective, When pickling increases the amount of washing, very fine irregularities are formed on the surface of the steel sheet, increasing the surface area per unit area of the steel sheet, thereby increasing the adhesion of the plating film per unit area of the steel sheet. This is thought to be due to the fact that the Pickling weight loss is 400mg/ m2
If it is less than that, the increase in surface area per unit area of the steel plate will be small, and sufficient low-temperature impact adhesion after coating of the plating film will not be obtained. In order to pickle a steel plate so that the pickling loss is 400 mg/ m2 or more, 150 to 300 g/(8.15 to 16.3
It is necessary to immerse the steel plate for a predetermined time in a sulfuric acid pickling bath with a concentration of % by volume). If the sulfuric acid concentration in the pickling bath is less than 150 g/m 2 , the steel plate cannot be pickled so that the pickling loss is 400 mg/m 2 or more. On the other hand, if the sulfuric acid concentration in the pickling bath exceeds 300g/, the amount of Fe dissolved in the pickling bath increases, resulting in deterioration of the pickling bath and an increase in the frequency of renewal, which becomes uneconomical. [Example] The present invention will be explained in more detail with reference to Examples. As a pretreatment for plating, the steel plate is pickled with a pickling amount within the range of the present invention, and then the steel plate is subjected to a specified electrolytic zinc-nickel alloy plating,
Plated steel plates Nos. 1 to 6 of the present invention were manufactured. and,
After three coats were applied to plated steel plates No. 1 to 6 of the present invention, a diamond shot test was conducted at low temperature to examine the low-temperature impact adhesion of the plated film after coating. For comparison, a steel plate was pickled with a pickling weight outside the range of this invention, and then the steel plate was electrolytically plated with a zinc-nickel alloy to obtain comparative plated steel plates Nos. 1 and 2. manufacture, as well as
Three coats were applied and a diamond shot test was conducted at low temperature. The conditions for pickling are as follows. Present invention Nos. 1 to 6. Immersion pickling bath: H 2 SO 4 150 to 300 g/, bath temperature: 35 to 60°C, immersion time: 6 to 30 seconds. Comparison No. 1. Immersion pickling bath: H 2 SO 4 80g/, Bath temperature: 25℃, Immersion time: 6 seconds. Comparison No. 2. Electrolytic pickling bath: HCl 10g/, Bath temperature: 20℃, Electrolysis time: 1.2 seconds, Current density: 10A/ dm2 . The plating bath composition and plating conditions are as follows. Plating bath composition. ZnSO 4 7H 2 O: 150g/, NiSO 4 7H 2 O: 350g/, Na 2 SO 4 : 55g/. Plating conditions. Plating bath PH: 1.3, plating bath temperature: 50℃, current density: 50A/ dm2 , plating amount: 20g/ m2 . The pretreatment chemical conversion treatment for the 3-coat painting was carried out under standard conditions using a dip type phosphate treatment solution (commercial product manufactured by Nihon Parkerizing Co., Ltd.) commonly used by automobile manufacturers. The 3-coat painting was performed as follows. undercoat. Using cationic type ED coating (electrodeposition coating), a standard coating of 20 μm and baking was performed using commercially available ED paint manufactured by Nippon Paint Co., Ltd. Intermediate coating. Using commercially available intermediate paint manufactured by Kansai Paint Co., Ltd.,
A standard intermediate coat of 35 μm was applied and baked. Top coat. Using commercially available intermediate paint manufactured by Kansai Paint Co., Ltd.,
A standard topcoat of 35μm and baking was applied. The diamond shot test at low temperature was conducted as follows. The sample coated with 3 coats was cooled to -20°C, and industrial diamond was heated to 170°C.
Shot at 10 locations on the sample at a speed of Km/hr.
The shot areas were taped with adhesive tape, and the presence or absence of peeling of the paint film and plating film was examined. The results of the diamond shot test are shown in Table 1, along with the loss of pickling.
以上説明したように、この発明によれば、めつ
き皮膜が塗装後の低温における衝撃に対して塗膜
と共に剥離することのない、塗装後の低温衝撃密
着性に優れためつき皮膜を有する電気亜鉛−ニツ
ケル合金めつき鋼板を製造することができる。ま
た、そのために、めつきの前処理の酸洗の条件を
強化するだけで済み、めつき技術を変更すること
を要しないので、容易である。
As explained above, according to the present invention, the electrolytic zinc oxide film has a plating film with excellent low-temperature impact adhesion after painting, and the plating film does not peel off together with the paint film due to impact at low temperatures after painting. - Nickel alloy plated steel sheets can be produced. Moreover, for this purpose, it is only necessary to strengthen the pickling conditions in the pretreatment for plating, and there is no need to change the plating technique, so it is easy.
Claims (1)
るにあたり、前記めつきの処理前に、前記鋼板の
酸洗減量が400mg／m2以上となるように、150〜
300ｇ／の濃度の硫酸酸洗浴中に前記鋼板を浸
漬することにより前記鋼板を酸洗して、前記鋼板
表面の酸化物皮膜を除去すると共に、前記鋼板の
表面に微細な凹凸を形成して前記表面を括性化さ
せ、次いで、前記鋼板に対し、電気亜鉛−ニツケ
ル合金めつき処理を旋すことを特徴とする、塗装
後の低温衝撃密着性に優れためつき皮膜を有する
電気亜鉛−ニツケル合金めつき鋼板の製造方法。1. When subjecting a steel plate to electrolytic zinc-nickel alloy plating, before the plating process, the steel plate must be heated with 150 to 150 mg/m2 so that the pickling loss of the steel plate is 400 mg/m2 or more .
The steel plate is pickled by immersing it in a sulfuric acid pickling bath with a concentration of 300 g/ml to remove the oxide film on the surface of the steel plate and form fine irregularities on the surface of the steel plate. An electrolytic zinc-nickel alloy having a tanning film with excellent low-temperature impact adhesion after coating, characterized by subjecting the steel plate to a galvanized surface and then subjecting the steel plate to an electrolytic zinc-nickel alloy plating treatment. Method for producing plated steel sheets.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23017886A JPS6386888A (en) | 1986-09-30 | 1986-09-30 | Production of zinc-nickel alloy electroplated steel sheet with plated film having superior adhesion under shock at low temperature after painting |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23017886A JPS6386888A (en) | 1986-09-30 | 1986-09-30 | Production of zinc-nickel alloy electroplated steel sheet with plated film having superior adhesion under shock at low temperature after painting |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6386888A JPS6386888A (en) | 1988-04-18 |
| JPH0563558B2 true JPH0563558B2 (en) | 1993-09-10 |
Family
ID=16903826
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP23017886A Granted JPS6386888A (en) | 1986-09-30 | 1986-09-30 | Production of zinc-nickel alloy electroplated steel sheet with plated film having superior adhesion under shock at low temperature after painting |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6386888A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103898575A (en) * | 2013-06-04 | 2014-07-02 | 无锡市锡山区鹅湖镇荡口青荡金属制品厂 | Pre-electrogalvanizing nickel alloy process for chemical plating of nickel on surface of magnesium alloy |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6393888A (en) * | 1986-10-06 | 1988-04-25 | Kobe Steel Ltd | Zinc alloy electroplated steel sheet having superior resistance to exfoliation by shock after coating |
| JP5817770B2 (en) * | 2013-03-26 | 2015-11-18 | Ｊｆｅスチール株式会社 | Method for producing high-strength cold-rolled steel sheet with excellent chemical conversion properties and corrosion resistance after coating, and good sliding properties |
| KR102218449B1 (en) | 2018-12-19 | 2021-02-19 | 주식회사 포스코 | Electroplated steel sheet having excellent surface appearance and method of manufacturing the same |
-
1986
- 1986-09-30 JP JP23017886A patent/JPS6386888A/en active Granted
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103898575A (en) * | 2013-06-04 | 2014-07-02 | 无锡市锡山区鹅湖镇荡口青荡金属制品厂 | Pre-electrogalvanizing nickel alloy process for chemical plating of nickel on surface of magnesium alloy |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6386888A (en) | 1988-04-18 |
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