JPH0430476B2 - - Google Patents
Info
- Publication number
- JPH0430476B2 JPH0430476B2 JP61289938A JP28993886A JPH0430476B2 JP H0430476 B2 JPH0430476 B2 JP H0430476B2 JP 61289938 A JP61289938 A JP 61289938A JP 28993886 A JP28993886 A JP 28993886A JP H0430476 B2 JPH0430476 B2 JP H0430476B2
- Authority
- JP
- Japan
- Prior art keywords
- chromate
- corrosion resistance
- aqueous solution
- acidic aqueous
- steel sheet
- 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
- ZCDOYSPFYFSLEW-UHFFFAOYSA-N chromate(2-) Chemical compound [O-][Cr]([O-])(=O)=O ZCDOYSPFYFSLEW-UHFFFAOYSA-N 0.000 claims description 53
- 230000007797 corrosion Effects 0.000 claims description 30
- 238000005260 corrosion Methods 0.000 claims description 30
- 239000007864 aqueous solution Substances 0.000 claims description 23
- 229910000831 Steel Inorganic materials 0.000 claims description 19
- 230000002378 acidificating effect Effects 0.000 claims description 19
- 239000010959 steel Substances 0.000 claims description 19
- 150000001875 compounds Chemical class 0.000 claims description 17
- 238000000034 method Methods 0.000 claims description 16
- 229910052751 metal Inorganic materials 0.000 claims description 15
- 239000002184 metal Substances 0.000 claims description 15
- 238000005868 electrolysis reaction Methods 0.000 claims description 14
- 238000007747 plating Methods 0.000 claims description 14
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 10
- 150000003839 salts Chemical class 0.000 claims description 8
- 238000005406 washing Methods 0.000 claims description 8
- 239000013522 chelant Chemical class 0.000 claims description 7
- 238000004519 manufacturing process Methods 0.000 claims description 6
- 239000011701 zinc Substances 0.000 claims description 5
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 4
- KRVSOGSZCMJSLX-UHFFFAOYSA-L chromic acid Substances O[Cr](O)(=O)=O KRVSOGSZCMJSLX-UHFFFAOYSA-L 0.000 claims description 4
- 239000011737 fluorine Substances 0.000 claims description 4
- 229910052731 fluorine Inorganic materials 0.000 claims description 4
- AWJWCTOOIBYHON-UHFFFAOYSA-N furo[3,4-b]pyrazine-5,7-dione Chemical compound C1=CN=C2C(=O)OC(=O)C2=N1 AWJWCTOOIBYHON-UHFFFAOYSA-N 0.000 claims description 4
- 229920000592 inorganic polymer Chemical class 0.000 claims description 4
- 150000002500 ions Chemical class 0.000 claims description 4
- 229920000620 organic polymer Chemical class 0.000 claims description 4
- 229910052725 zinc Inorganic materials 0.000 claims description 4
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 claims description 3
- 239000010960 cold rolled steel Substances 0.000 claims description 3
- 150000001450 anions Chemical class 0.000 claims description 2
- 239000011651 chromium Substances 0.000 description 76
- 229910052804 chromium Inorganic materials 0.000 description 17
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 16
- 238000000576 coating method Methods 0.000 description 11
- 239000011248 coating agent Substances 0.000 description 10
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 6
- 150000001449 anionic compounds Chemical class 0.000 description 6
- 229910001412 inorganic anion Inorganic materials 0.000 description 6
- 238000006722 reduction reaction Methods 0.000 description 6
- 229910045601 alloy Inorganic materials 0.000 description 5
- 239000000956 alloy Substances 0.000 description 5
- 239000003973 paint Substances 0.000 description 5
- 230000009467 reduction Effects 0.000 description 5
- 239000000243 solution Substances 0.000 description 5
- 229910001297 Zn alloy Inorganic materials 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 4
- 239000003638 chemical reducing agent Substances 0.000 description 4
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 3
- 229910001335 Galvanized steel Inorganic materials 0.000 description 3
- 229910018605 Ni—Zn Inorganic materials 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000008397 galvanized steel Substances 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 3
- 229910021645 metal ion Inorganic materials 0.000 description 3
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 150000001735 carboxylic acids Chemical class 0.000 description 2
- JOPOVCBBYLSVDA-UHFFFAOYSA-N chromium(6+) Chemical compound [Cr+6] JOPOVCBBYLSVDA-UHFFFAOYSA-N 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 238000010422 painting Methods 0.000 description 2
- 150000002989 phenols Chemical class 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 230000001603 reducing effect Effects 0.000 description 2
- 239000007921 spray Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 241001163841 Albugo ipomoeae-panduratae Species 0.000 description 1
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- WQZGKKKJIJFFOK-GASJEMHNSA-N Glucose Natural products OC[C@H]1OC(O)[C@H](O)[C@@H](O)[C@@H]1O WQZGKKKJIJFFOK-GASJEMHNSA-N 0.000 description 1
- HSRJKNPTNIJEKV-UHFFFAOYSA-N Guaifenesin Chemical compound COC1=CC=CC=C1OCC(O)CO HSRJKNPTNIJEKV-UHFFFAOYSA-N 0.000 description 1
- 229920000877 Melamine resin Polymers 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 1
- WGLPBDUCMAPZCE-UHFFFAOYSA-N Trioxochromium Chemical compound O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 239000003929 acidic solution Substances 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 229920000180 alkyd Polymers 0.000 description 1
- 125000003368 amide group Chemical group 0.000 description 1
- 150000001412 amines Chemical class 0.000 description 1
- 125000003277 amino group Chemical group 0.000 description 1
- QGZKDVFQNNGYKY-UHFFFAOYSA-N ammonia Natural products N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 description 1
- 239000004327 boric acid Substances 0.000 description 1
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- -1 chromate compound Chemical class 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- SOCTUWSJJQCPFX-UHFFFAOYSA-N dichromate(2-) Chemical compound [O-][Cr](=O)(=O)O[Cr]([O-])(=O)=O SOCTUWSJJQCPFX-UHFFFAOYSA-N 0.000 description 1
- 238000010790 dilution Methods 0.000 description 1
- 239000012895 dilution Substances 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000004070 electrodeposition Methods 0.000 description 1
- 238000009713 electroplating Methods 0.000 description 1
- 238000005246 galvanizing Methods 0.000 description 1
- 239000008103 glucose Substances 0.000 description 1
- 235000011187 glycerol Nutrition 0.000 description 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 150000002484 inorganic compounds Chemical class 0.000 description 1
- 229910010272 inorganic material Inorganic materials 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- JDSHMPZPIAZGSV-UHFFFAOYSA-N melamine Chemical compound NC1=NC(N)=NC(N)=N1 JDSHMPZPIAZGSV-UHFFFAOYSA-N 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 235000021317 phosphate Nutrition 0.000 description 1
- 150000003013 phosphoric acid derivatives Chemical class 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 150000003217 pyrazoles Chemical class 0.000 description 1
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 241000894007 species Species 0.000 description 1
- 238000002798 spectrophotometry method Methods 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 235000000346 sugar Nutrition 0.000 description 1
- 150000008163 sugars Chemical class 0.000 description 1
- 125000000542 sulfonic acid group Chemical group 0.000 description 1
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 1
- 150000003852 triazoles Chemical class 0.000 description 1
- 229920003169 water-soluble polymer Polymers 0.000 description 1
Landscapes
- Chemical Treatment Of Metals (AREA)
- Electroplating Methods And Accessories (AREA)
Description
（産業上の利用分野）
本発明は各種亜鉛系メツキ鋼板の耐食性、塗装
性等の表面特性を向上させる目的で行われる電解
クロメート処理亜鉛系メツキ鋼板の製造方法に関
するものである。
（従来の技術）
一般にクロメートは亜鉛、アルミニウムおよび
これらの金属を主成分とする合金メツキ鋼板に広
く利用されている。クロメート処理はクロメート
処理液を金属メツキ表面に塗布したのち乾燥又は
焼付ける塗布クロメート方法、金属メツキをクロ
メート処理液に浸漬又はスプレー処理したのち水
洗し乾燥する反応クロメート方法、およびクロメ
ート処理液中にメツキ鋼板を浸漬し電解する電解
クロメート方法に大別できる。それぞれの方法は
一長一短があり、目的とする品質、処理設備およ
びメツキ金属によつて選択して使用されている。
本発明は陰極で処理する電解クロメート処理に
関するものであり、以下、本発明に関連する公知
技術について述べる。
従来の陰極電解クロメートは基本的に金属表面
技術便覧347〜359に述べられているように有名な
サージエント浴（CrO3／H2SO4＝250／2.5ｇ／
）から出発している。実用されているものとし
て、サージエント浴を稀釈したもの、フツ素イオ
ン浴、ケイフツ素イオン浴、SRHS浴等クロムメ
ツキをメツキのクロメートに応用したものが殆ん
どである。いずれも陰極面での六価クロム（以下
Cr6+）の還元によつて金属クロムおよび三価クロ
ム（以下Cr3+）主体の不溶性のクロメート化合物
を形成させる方法である。クロムの還元反応は陰
極表面に形成する硫酸等の触媒層を通して進むと
説明されている。
（発明が解決しようとする問題点）
従来の方法は形成されるクロメート被膜が金属
クロム（以下Cr0）および三価クロム（Cr3+）を
主体としているためCr6+に依存する耐食性が不充
分である。Cr6+主体の電解クロメートは殆んど見
当らず、ましてCr3+／Cr6+を制御した電解クロメ
ートは公知技術にはない。又、クロメート処理液
中に硫酸イオン、を含んだPHが２以下の強酸性液
であるためメツキ金属との化学反応が電解反応と
同時あるいはその前後に生ずるため外観を均一に
仕上げることが難しい。更にメツキ金属の表面状
態、合金成分等によつて著しく影響を受け、メツ
キ金属に合せたいくつもの処理浴、処理条件を設
けなければならない。
本発明は従来の電解クロメート被膜がCr0，
Cr3+主体のクロメート被膜であるために生ずる耐
食性不良を解決したCr6+，Cr3+から構成される耐
食性、密着性に優れた電解クロメートを効率よく
得る方法を提供するものである。
（問題点を解決するための手段）
本発明は、冷延鋼板に亜鉛系メツキを行つた
後、Cr3+／（Cr3+＋Cr6+）の比が0.1〜0.7未満の
全Crの濃度５−100ｇ／の還元クロム酸、
SO4 2-を全Cr1に対して0.01〜0.1含有する酸性水
溶液中で陰極電解した後水洗することを特徴とす
る耐食性に優れた電解クロメート処理亜鉛系メツ
キ鋼板の製造方法である。その場合、C1-，
NO3 -フツ素錯イオンから選択したアニオンと
SO4 2-の総和が全Cr1に対して0.01〜0.1含有する
酸性水溶液中で電解した後水洗することができ、
又、２価以上の金属塩、無機高分子化合物、有機
高分子化合物、キレート化合物の１種以上を含む
酸性水溶液中で陰極電解した後水洗することもで
きる。
（作用）
以下本発明の製造方法について述べる。
本発明に使用する酸性水溶液はCr3+，Cr6+と無
機アニオン（〔Am-〕と表示）で構成される。
Cr3+およびCr6+はクロム還元比（Cr3+／（Cr3+
＋Cr6+として計算される）が0.1〜0.7未満であ
る。全クロム（Cr3+＋Cr6+）の濃度は５〜100
ｇ／であり、10〜30ｇ／が好ましい。クロム
還元比は本発明で最も重要な要素である。0.1未
満では以下述べる如く効率良くクロメート被膜を
析出できず、品質的にも耐食性が得られない。又
0.7以上では耐食性が悪いクロメート被膜しか得
られない。クロム還元比は0.2〜0.4が最も効率よ
く品質に優れたクロメート被膜を得ることが出来
る。クロム還元比は無水クロム酸水溶液に、還元
剤を加えて調合する。還元剤としては有機還元剤
が適用できるが、望しくは残査物の残らない糖
類、アルコール類、フエノール類、オキシカルボ
ン酸、カルボン酸等の有機還元剤が望ましい。
又、無機アニオン／全クロム比の許容内でCr3+の
無機化合物を加えても良い。
無機アニオンはSO4 2-，Cl-，NO3 -，F-、フツ
素錯イオンである。無機アニオンの量は無機アニ
オン／全クロム比が0.01〜0.1に規定するのが好
ましい。これらの無機アニオンは、酸性水溶液の
電気伝導度の向上、メツキ金属の界面における還
元作用によりクロメート被膜の密着性を向上させ
るために加える。その効果は0.01以上が望ましく
0.1超では電解以外の化学反応により品質不良が
生じやすい。
本発明で使用する酸性水溶液中には品質向上の
ために更に副成分を加える場合がある。副成分と
しては２価以上の金属塩、無機高分子化合
物、有機高分子化合物、キレート化合物であ
る。これらの化合物はクロメート被膜と共に析出
し、被膜の耐食性、塗料密着性、塗装後の耐食性
を向上させる。
以下各化合物について述べる。
２価以上の金属塩とはMg2-，Ca2+，Zn2+，
Al3+，Fe2+，Co2+，Ni2+，Sn2+の塩および
MoO4 2-，WO4 2-，MnO4 2-を言う。これらの金
属イオンはクロメートの電析時にクロム酸塩、重
クロム酸塩もしくは酸化物として析出し、六価ク
ロムを固定化し、耐食性を向上させる。添加量は
Men+〔Cr2O7〕2-（-n2）＋Men+・〔Am-〕（ｎ／ｍ）
で表されるMen+を上限値として加える。
無機高分子化合物は粒径が100mμ以下のゾル、
例えばシリカゾル、ジルコニヤゾル、酸化チタン
ゾル、アルミナゾルで一部分カチオン化したゾル
も含まれる。これらのゾルはクロムメート皮膜に
共析又は表面濃化し、耐食性、塗料密着性を向上
させる。添加量は全クロムに対して0.1〜1.0が望
ましい。
有機高分子化合物は、水溶性、水分散性の高分
子化合物で、親水基としてカルボキシル基、ヒド
ロキシル基、アミド基、アミン基、スルホン酸基
を含む化合物である。これらの高分子はCr3+とキ
レート結合して皮膜自身の耐食性、密着加工性を
付与する他、Cr6+を固定する作用がある。添加量
は全クロムに対し0.1〜1.0が望ましい。
キレート化合物はアミン類、ピラゾール類、フ
エノール類、縮合リン酸塩、トリアゾール、カル
ボン酸類である。これらのキレート化合物は被膜
中のCr3+とキレート結合し被膜の品質を改良する
とともに水溶液中のCr6+の安定化に有益である。
酸性水溶液のPHは１〜５の範囲が好ましい。PH
１未満はメツキの溶解に基づく化学反応が生じ良
質のクロメートが得られない。又、PH５超ではク
ロメートの析出効率が著るしく劣化する。酸性水
溶液温は20〜60℃の通常の電解処理が行われる温
度で処理が可能である。
電解方式としてはメツキ鋼板を陰極として通電
する方法を採用する。
本発明は酸性水溶液中で電解したあと水洗し、
乾燥する方法である。
第１図はクロム還元比が0.2の無水クロム酸
（全クロム濃度15ｇ／）と硫酸1.2ｇ／（無機
アニオン／全クロム比が0.08）の酸性水溶液（PH
＝２）中で電気亜鉛メツキ鋼板（EG）、12％Ni
−Zn合金メツキ鋼（EA）を陰極として電流密度
3A／ｄm2で電解した時の通電量（クーロン／ｄ
m2）とクロメート被膜量（全クロム付着量：T.
Crmg／m2）で示した例である。比較としてEAに
ついて公知のサージエント浴の５倍稀釈液中で電
解した結果をＰで示した。本発明の処理方法で処
理したEA，EGは殆んど同一の挙動を示し、公知
のＰに比し、少い通電量で高付着量が得られる。
被膜は非常に均一で密着性、耐食性に優れてい
る。特に密着性はＴ折曲げで全く剥離しなかつ
た。これは従来のクロメートから得られる被膜と
比較すると飛躍的に向上している。
（実施例）
以下、本発明の実施例を示す。
実施例中の記号、評価法について次に示す。
全クロム付着量は５％HClで溶解し、厚子吸光
光度法で分析し、mg／m2で表示した。
無塗装の耐食性は塩水噴霧試験で行い、評価と
して白錆発生までの時間で示した。
塗装板の密着性はＴ折曲げテーピングで示し、
良好のもの「◎」、剥離「×」で示した。
塗装後の２次密着性は、塗装板に人工傷を入
れ、塩水噴霧試験168時間後、テーピングによつ
て人工傷からの剥離巾（mm）で示した。
塗料は市販のメラミンアルキツド樹脂塗料25μ
目標で塗装し評価した。
実施例 １
冷延鋼板を公知の方法で脱脂、酸洗し、12％の
Niを含むNi−Zn合金メツキを両面に20ｇ／m2メ
ツキしたのち、第１表に示す酸性水溶液中で電流
密度1.5A／ｄm2で通電量20クーロン／ｄm2の陰
極電解処理を行ない、ただちに水洗して電解クロ
メート処理メツキ鋼板を作成した。
(Field of Industrial Application) The present invention relates to a method for producing electrolytically chromate-treated zinc-plated steel sheets, which is carried out for the purpose of improving the surface properties such as corrosion resistance and paintability of various zinc-plated steel sheets. (Prior Art) Generally, chromate is widely used in zinc, aluminum, and alloy plated steel sheets containing these metals as main components. Chromate treatment includes the coating chromate method, in which a chromate treatment solution is applied to the surface of the metal plating and then dried or baked, the reactive chromate method, in which the metal plating is immersed or sprayed in the chromate treatment solution, then washed with water and dried, and the method in which the metal plating is coated in the chromate treatment solution. It can be broadly divided into electrolytic chromate methods, in which the steel plate is immersed and electrolyzed. Each method has its advantages and disadvantages, and is selected and used depending on the desired quality, processing equipment, and plating metal. The present invention relates to electrolytic chromate treatment using a cathode, and the known techniques related to the present invention will be described below. Conventional cathodic electrolytic chromate is basically produced using the famous sergeant bath (CrO 3 /H 2 SO 4 = 250/2.5g/
). Most of the ones in practical use are diluted sergeant baths, fluorine ion baths, fluorine ion baths, SRHS baths, etc., which are applied to chromate plating. In both cases, hexavalent chromium (hereinafter referred to as
In this method, an insoluble chromate compound mainly consisting of metallic chromium and trivalent chromium (hereinafter referred to as Cr 3+ ) is formed by reduction of Cr 6+ ). It is explained that the reduction reaction of chromium proceeds through a catalyst layer of sulfuric acid or the like formed on the surface of the cathode. (Problems to be solved by the invention) In the conventional method, the formed chromate film mainly consists of metallic chromium (hereinafter referred to as Cr 0 ) and trivalent chromium (Cr 3+ ), so the corrosion resistance dependent on Cr 6+ is insufficient. That's enough. Almost no electrolytic chromate based on Cr 6+ has been found, and even less an electrolytic chromate in which Cr 3+ /Cr 6+ is controlled is not known in the art. Furthermore, since the chromate treatment solution is a strongly acidic solution containing sulfate ions with a pH of 2 or less, a chemical reaction with the plating metal occurs at the same time as or before or after the electrolytic reaction, making it difficult to achieve a uniform appearance. Furthermore, it is significantly affected by the surface condition of the plating metal, alloy components, etc., and a number of treatment baths and treatment conditions must be provided to match the plating metal. The present invention shows that the conventional electrolytic chromate coating has Cr 0 ,
The present invention provides a method for efficiently obtaining electrolytic chromate, which is composed of Cr 6+ and Cr 3+ and has excellent corrosion resistance and adhesion, which solves the problem of poor corrosion resistance caused by the chromate coating mainly consisting of Cr 3+ . (Means for Solving the Problems) The present invention provides a method for reducing the total Cr concentration such that the ratio of Cr 3+ /(Cr 3+ +Cr 6+ ) is 0.1 to less than 0.7 after performing zinc plating on a cold rolled steel sheet. 5-100g/reduced chromic acid,
This is a method for producing an electrolytic chromate-treated zinc-plated steel sheet with excellent corrosion resistance, which is characterized by carrying out cathodic electrolysis in an acidic aqueous solution containing 0.01 to 0.1 of SO 4 2- based on the total Cr1, followed by washing with water. In that case, C1 - ,
Anion selected from NO 3 -fluorine complex ion and
It can be washed with water after electrolysis in an acidic aqueous solution containing 0.01 to 0.1 of SO 4 2- to total Cr1,
It is also possible to carry out cathodic electrolysis in an acidic aqueous solution containing one or more of divalent or higher valent metal salts, inorganic polymer compounds, organic polymer compounds, and chelate compounds, followed by washing with water. (Function) The manufacturing method of the present invention will be described below. The acidic aqueous solution used in the present invention is composed of Cr 3+ , Cr 6+ and an inorganic anion (expressed as [A m- ]). Cr 3+ and Cr 6+ are determined by the chromium reduction ratio (Cr 3+ / (Cr 3+
+Cr 6+ ) is between 0.1 and less than 0.7. The concentration of total chromium (Cr 3+ + Cr 6+ ) is 5 to 100
g/, preferably 10 to 30 g/. The chromium reduction ratio is the most important factor in the present invention. If it is less than 0.1, a chromate film cannot be deposited efficiently as described below, and corrosion resistance cannot be obtained in terms of quality. or
If it is 0.7 or more, only a chromate film with poor corrosion resistance can be obtained. A chromium reduction ratio of 0.2 to 0.4 is most efficient and allows a chromate film of excellent quality to be obtained. The chromium reduction ratio is prepared by adding a reducing agent to an aqueous chromic acid anhydride solution. As the reducing agent, organic reducing agents can be used, but organic reducing agents such as sugars, alcohols, phenols, oxycarboxylic acids, and carboxylic acids that do not leave any residue are preferable.
Further, an inorganic compound of Cr 3+ may be added within the allowable range of the inorganic anion/total chromium ratio. Inorganic anions are SO 4 2- , Cl - , NO 3 - , F - and fluorine complex ions. The amount of inorganic anions is preferably defined so that the inorganic anion/total chromium ratio is 0.01 to 0.1. These inorganic anions are added to improve the electrical conductivity of the acidic aqueous solution and to improve the adhesion of the chromate film through a reducing action at the interface of the plating metal. The effect is preferably 0.01 or more.
If it exceeds 0.1, quality defects are likely to occur due to chemical reactions other than electrolysis. Additional subcomponents may be added to the acidic aqueous solution used in the present invention to improve quality. Sub-components include metal salts with a valence of two or more, inorganic polymer compounds, organic polymer compounds, and chelate compounds. These compounds precipitate together with the chromate film and improve the corrosion resistance of the film, paint adhesion, and corrosion resistance after painting. Each compound will be described below. Metal salts with a valence of 2 or more are Mg 2- , Ca 2+ , Zn 2+ ,
Salts of Al 3+ , Fe 2+ , Co 2+ , Ni 2+ , Sn 2+ and
MoO 4 2- , WO 4 2- , MnO 4 2- . These metal ions are deposited as chromate, dichromate, or oxide during chromate electrodeposition, fix hexavalent chromium, and improve corrosion resistance. The amount added is
Me n+ [Cr 2 O 7 ] 2- ( - n2) + Me n+・[A m- ] (n/m)
Add Men n+ expressed as the upper limit. Inorganic polymer compounds are sol with a particle size of 100 mμ or less,
For example, silica sol, zirconia sol, titanium oxide sol, and alumina sol that are partially cationized are also included. These sols eutectoid or surface concentrate on the chromate film, improving corrosion resistance and paint adhesion. The amount added is preferably 0.1 to 1.0 based on the total chromium. The organic polymer compound is a water-soluble or water-dispersible polymer compound containing a carboxyl group, a hydroxyl group, an amide group, an amine group, or a sulfonic acid group as a hydrophilic group. These polymers form a chelate bond with Cr 3+ to give the film its own corrosion resistance and adhesion processability, and also have the effect of fixing Cr 6+ . The amount added is preferably 0.1 to 1.0 relative to the total chromium. Chelate compounds are amines, pyrazoles, phenols, condensed phosphates, triazoles, and carboxylic acids. These chelate compounds chelate with Cr 3+ in the coating to improve the quality of the coating and are useful for stabilizing Cr 6+ in the aqueous solution. The pH of the acidic aqueous solution is preferably in the range of 1 to 5. PH
If it is less than 1, a chemical reaction based on the dissolution of the plating will occur and good quality chromate will not be obtained. Moreover, at pH exceeding 5, the chromate precipitation efficiency deteriorates significantly. The acidic aqueous solution temperature can be 20 to 60°C, which is the temperature at which normal electrolytic treatment is performed. The electrolytic method uses a galvanized steel plate as a cathode to conduct electricity. The present invention involves electrolyzing in an acidic aqueous solution and then washing with water.
This is a drying method. Figure 1 shows an acidic aqueous solution (PH
=2) Electrogalvanized steel sheet (EG), 12% Ni
−Current density using Zn alloy plated steel (EA) as cathode
Amount of current (coulombs/d) when electrolyzed at 3A/ dm2
m 2 ) and chromate coating amount (total chromium coating amount: T.
Crmg/m 2 ). For comparison, the results of electrolysis of EA in a 5-fold dilution of a known sergeant bath are shown as P. EA and EG treated by the treatment method of the present invention show almost the same behavior, and compared to known P, a high adhesion amount can be obtained with a small amount of current applied.
The coating is extremely uniform and has excellent adhesion and corrosion resistance. In particular, the adhesion was such that no peeling occurred during T-bending. This is a dramatic improvement compared to films obtained from conventional chromates. (Example) Examples of the present invention will be shown below. Symbols and evaluation methods in Examples are shown below. The total amount of chromium deposited was dissolved in 5% HCl, analyzed by Atsuko spectrophotometry, and expressed in mg/m 2 . Corrosion resistance of unpainted products was measured by a salt spray test, and the evaluation was expressed as the time until white rust appeared. The adhesion of the painted board is indicated by T-fold taping.
Good results were indicated by "◎" and peeling was indicated by "x". The secondary adhesion after painting was determined by making an artificial scratch on the coated plate and measuring the peeling width (mm) from the artificial scratch by taping after 168 hours of a salt spray test. The paint is commercially available melamine alkyd resin paint 25μ.
The target was painted and evaluated. Example 1 A cold-rolled steel plate was degreased and pickled using a known method, and a 12%
After plating Ni-Zn alloy containing Ni at 20 g/m 2 on both sides, cathodic electrolysis treatment was performed at a current density of 1.5 A/dm 2 and a current flow rate of 20 coulombs/dm 2 in an acidic aqueous solution shown in Table 1. It was immediately washed with water to create an electrolytically chromate-treated plated steel plate.
【表】【table】
【表】
No.１〜４は、Cr3+／（Cr3+＋Cr6+）が0.1〜
0.70未満の本発明方法によつて製造した例であ
る。Cr3+／（Cr3+＋Cr6+）が0.30まではCr付着量
がCr3+量に比例して増大し、耐食性が良好であ
る。Cr3+／（Cr3+＋Cr6+）が0.70では耐食性が低
下する。No.６，７は、Cr3+／（Cr3+＋Cr6+）が一
定で、〔Am-〕／全Crを0.016および0.08の酸性水
溶液から得たものである。又、No.８はNo.２の酸性
水溶液のPHをアンモニア水で高めた例である。No.
９はCr3+／（Cr3+＋Cr6+）が本発明の要件とする
範囲よりも小さい酸性水溶液を用いた比較例であ
り、Cr付着量が少く耐食性も良くない。
実施例 ２
冷延鋼板を公知の方法で脱脂、酸洗後電気亜鉛
メツキを3μ行つた電気亜鉛メツキ鋼板（記号
EG）、3μの12％Ni−Zn合金メツキ鋼板（EA）お
よび10μの溶融亜鉛メツキを行つた溶融亜鉛メツ
キ鋼板（GI）に第２表に示したグリセリンで還
元した酸性水溶液で陰極電解処理を行つた。水洗
後、乾燥してクロメート処理メツキ鋼板を作成し
た。[Table] For No. 1 to 4, Cr 3+ / (Cr 3+ + Cr 6+ ) is 0.1 to
This is an example produced by the method of the present invention with a value of less than 0.70. When Cr 3+ /(Cr 3+ +Cr 6+ ) is up to 0.30, the amount of Cr deposited increases in proportion to the amount of Cr 3+ and the corrosion resistance is good. When Cr 3+ /(Cr 3+ +Cr 6+ ) is 0.70, corrosion resistance decreases. Nos. 6 and 7 had a constant Cr 3+ /(Cr 3+ +Cr 6+ ) and were obtained from acidic aqueous solutions with [A m- ]/total Cr of 0.016 and 0.08. Moreover, No. 8 is an example in which the pH of the acidic aqueous solution of No. 2 was increased with aqueous ammonia. No.
Sample No. 9 is a comparative example using an acidic aqueous solution in which Cr 3+ /(Cr 3+ +Cr 6+ ) is smaller than the range required by the present invention, and the amount of Cr deposited is small and the corrosion resistance is not good. Example 2 An electrogalvanized steel sheet (symbol:
EG), 3μ 12% Ni-Zn alloy plated steel sheet (EA) and 10μ hot dip galvanized steel sheet (GI) were subjected to cathodic electrolysis treatment with an acidic aqueous solution reduced with glycerin shown in Table 2. I went. After washing with water, it was dried to produce a chromate-treated plated steel plate.
【表】
実施例10〜13はNu−Zn合金メツキ鋼板に電流
密度を一定にして通電量を変えて実施した結界で
ある。仕上りの外観が均一で通電量に比例して
Cr付着量が増加し、耐食性、密着性が良好であ
つた。実施例14〜17は電気亜鉛メツキ鋼板に処理
した例であり、電解クロメートとしては良好な耐
食性を得た。実施例18〜20はNi−Zn合金メツキ
鋼板に電流密度を変えて電解した例である。いず
れも均一なクロメート外観を示し、耐食性、塗料
密着性が良好であつた。No.21は溶融亜鉛メツキに
処理した例である。No.22〜27は比較例で、〔Am
−〕／全Cr比が0.02と0.08の例を示した。Cr付着
量が少く、不均一である。品質的には、塗装性
（密着性、耐食性）が良好だが無塗装板の耐食性
が劣る。
実施例 ３
12％Niを含むNu−Zn合金メツキを電気メツキ
した後、ブドウ糖で部分還元したクロム酸水溶液
に硫酸および添加イオンを加えた第３表に示す水
溶液で、陰極電解クロメート処理を行い試験し
た。[Table] In Examples 10 to 13, barriers were created by changing the amount of current applied to Nu-Zn alloy plated steel plates while keeping the current density constant. The finished appearance is uniform and proportional to the amount of current applied.
The amount of Cr deposited increased, and corrosion resistance and adhesion were good. Examples 14 to 17 are examples in which electrolytic galvanized steel sheets were treated, and good corrosion resistance was obtained as an electrolytic chromate. Examples 18 to 20 are examples in which Ni--Zn alloy plated steel sheets were electrolyzed at different current densities. All exhibited uniform chromate appearance and had good corrosion resistance and paint adhesion. No. 21 is an example of hot-dip galvanizing. Nos. 22 to 27 are comparative examples, [A m
− ]/total Cr ratios of 0.02 and 0.08 are shown. The amount of Cr deposited is small and uneven. In terms of quality, the paintability (adhesion, corrosion resistance) is good, but the corrosion resistance of uncoated boards is poor. Example 3 After electroplating Nu-Zn alloy plating containing 12% Ni, it was subjected to cathodic electrolytic chromate treatment using an aqueous solution shown in Table 3 in which sulfuric acid and additional ions were added to a chromic acid aqueous solution partially reduced with glucose. did.
【表】
No.29はホウ酸を加えた例、No.30は水溶性の高分
子化合物を加えた例で、いずれも耐食性が向上す
る。No.31〜35はシリカ、アルミナのゾル、金属イ
オンの添加例で耐食性が向上する。金属イオン添
加した33および35はやや密着性が低下した。No.38
はフツ素錯塩としてケイフツ素イオンを含む例
で、外観が均一で耐食の良好なクロメート皮膜付
合金メツキ鋼板が得られた。
（発明の効果）
本発明は高性能のクロメート特に耐食性に優れ
た被膜を亜鉛メツキ、亜鉛合金メツキ鋼板に形成
できる事は前述した通りである。クロメート被膜
はCr6+による耐食性付与とCr3+による難溶性化の
バランスのとれた被膜を定量的に均一に形成する
技術が望れていた。現在迄塗布クロメート、電解
クロメート、反応クロメートが数多く開発されて
来たが、いずれも一長一短があり、完全なもの、
今後開発する必要がある。本発明は公知クロメー
トに比し、格段に向上したバランスのとれたクロ
メート被膜を簡単に現行プロセスで製造すること
が出来、完全なクロメートに一歩近づいた技術で
ある。
更に、本発明はクロメート析出に対して金属表
面種の依存度が低く他の金属アルミニウム、鉄、
銅、等への適用も充分に効果を発揮する可能型の
クロメート処理方法である。
更に本発明は直流電解、交流電解による処理が
可能であり交流電解の場合、高価な整流機を必要
としない効果がある。[Table] No. 29 is an example in which boric acid was added, and No. 30 is an example in which a water-soluble polymer compound was added, both of which improve corrosion resistance. Nos. 31 to 35 are examples of adding silica, alumina sol, and metal ions to improve corrosion resistance. The adhesion of 33 and 35 to which metal ions were added was slightly lower. No.38
This is an example containing fluorine ion as a fluorine complex salt, and an alloy-plated steel sheet with a chromate film having a uniform appearance and good corrosion resistance was obtained. (Effects of the Invention) As described above, the present invention can form a high-performance chromate film, especially a coating with excellent corrosion resistance, on galvanized or zinc alloy-plated steel sheets. For chromate coatings, there has been a desire for a technology to quantitatively and uniformly form a coating with a good balance between corrosion resistance imparted by Cr 6+ and insolubility imparted by Cr 3+ . To date, many coated chromates, electrolytic chromates, and reactive chromates have been developed, but each has advantages and disadvantages.
This needs to be developed in the future. The present invention is a technology that can easily produce a well-balanced chromate film that is significantly improved compared to known chromates using current processes, and is one step closer to perfect chromate. Furthermore, the present invention has a low dependence on the metal surface species for chromate precipitation, and is compatible with other metals such as aluminum, iron,
This is a possible chromate treatment method that can be applied to copper, etc., and is fully effective. Furthermore, the present invention allows processing by direct current electrolysis or alternating current electrolysis, and in the case of alternating current electrolysis, an expensive rectifier is not required.
第１図はCr3+／（Cr3+＋Cr6+）＝0.2のクロム酸
と硫酸／全Cr＝0.08の水溶液で電気亜鉛メツキ
（EG）、12％Ni−Zn合金メツキ（EA）鋼板を陰
極電解した際の通電量とT.Crで表したクロメー
ト付着量の関係および比較例として公知のCrO3
−H2SO4浴(P)について示す図、第２図は本発明
の要件を満たす酸性水溶液を用いて処理した際の
電流密度とクロメート付着量の関係を示す図であ
る。
Figure 1 shows electrogalvanized (EG) and 12% Ni-Zn alloy plated (EA) steel sheets using an aqueous solution of chromic acid and sulfuric acid with Cr 3+ / (Cr 3+ + Cr 6+ ) = 0.2 and total Cr = 0.08. The relationship between the amount of current applied during cathodic electrolysis and the amount of chromate deposited in T.Cr, and the well-known CrO 3 as a comparative example
-H 2 SO 4 bath (P), Figure 2 is a diagram showing the relationship between current density and chromate deposition amount when treated using an acidic aqueous solution that satisfies the requirements of the present invention.
Claims (1)
（Cr3+＋Cr6+）の比が0.1〜0.7未満の全Crの濃度
５−100ｇ／の還元クロム酸、SO4 2-を全Cr1に
対して0.01−0.1含有する酸性水溶液中で陰極電
解した後水洗することを特徴とする耐食性に優れ
た電解クロメート処理亜鉛系メツキ鋼板の製造方
法。 ２ Cl-，NO3 -、フツ素錯イオンから選択した
アニオンとSO4 2-の総和が全Cr1に対して0.01〜
0.1含有する酸性水溶液中で陰極電解した後水洗
することを特徴とする特許請求の範囲第１項記載
の耐食性に優れた電解クロメート処理亜鉛系メツ
キ鋼板の製造方法。 ３ ２価以上の金属塩、無機高分子化合物、有機
高分子化合物、キレート化合物の１種以上を含む
酸性水溶液中で陰極電解した後水洗することを特
徴とする特許請求の範囲第１項、又は第２項記載
の耐食性に優れた電解クロメート処理亜鉛系メツ
キ鋼板の製造方法。[Claims] 1. After performing zinc plating on a cold rolled steel sheet, Cr 3+ /
Cathodic electrolysis in an acidic aqueous solution containing reduced chromic acid with a total Cr concentration of 5-100 g/SO 4 2- with a ratio of (Cr 3+ + Cr 6+ ) of 0.1 to less than 0.7 and 0.01-0.1 of SO 4 2- to total Cr1. A method for manufacturing an electrolytically chromate-treated zinc-plated steel sheet with excellent corrosion resistance, which comprises washing with water after washing. 2 The sum of anions selected from Cl - , NO 3 - and fluorine complex ions and SO 4 2- is 0.01 to 0.01 to total Cr1.
2. A method for producing an electrolytically chromate-treated zinc-plated steel sheet having excellent corrosion resistance, as set forth in claim 1, which comprises performing cathodic electrolysis in an acidic aqueous solution containing 0.1% and then washing with water. 3. Claim 1, characterized in that cathodic electrolysis is performed in an acidic aqueous solution containing one or more of divalent or higher metal salts, inorganic polymer compounds, organic polymer compounds, and chelate compounds, followed by washing with water, or 2. A method for producing an electrolytically chromate-treated zinc-plated steel sheet with excellent corrosion resistance, as described in item 2.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP28993886A JPS63143292A (en) | 1986-12-05 | 1986-12-05 | Production of electrolytically chromated steel sheet having excellent corrosion resistance |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP28993886A JPS63143292A (en) | 1986-12-05 | 1986-12-05 | Production of electrolytically chromated steel sheet having excellent corrosion resistance |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP20351691A Division JPH0696794B2 (en) | 1991-07-19 | 1991-07-19 | AC electrolytic chromate treatment plated steel sheet manufacturing method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS63143292A JPS63143292A (en) | 1988-06-15 |
| JPH0430476B2 true JPH0430476B2 (en) | 1992-05-21 |
Family
ID=17749685
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP28993886A Granted JPS63143292A (en) | 1986-12-05 | 1986-12-05 | Production of electrolytically chromated steel sheet having excellent corrosion resistance |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS63143292A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100349443B1 (en) * | 1998-09-17 | 2002-12-13 | 주식회사 포스코 | Manufacturing method of one-component tin-free steel with excellent secondary adhesion strength of coating film |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5332350A (en) * | 1976-09-06 | 1978-03-27 | Sutaa Denki Seizou Kk | Charging device with battery temperature detector |
| JPS5698496A (en) * | 1980-01-10 | 1981-08-07 | Nippon Kokan Kk <Nkk> | Chromate treating method of zinc alloy-electroplated steel plate |
| JPS5729597A (en) * | 1980-07-28 | 1982-02-17 | Teksid Spa | Long life thin plate for automobile body and method |
| JPS62107096A (en) * | 1985-11-01 | 1987-05-18 | Nippon Parkerizing Co Ltd | Surface treatment of galvanized steel sheet |
| JPS62278298A (en) * | 1985-08-28 | 1987-12-03 | Kawasaki Steel Corp | Chromated zn or zn alloy plated steel sheet and its production |
-
1986
- 1986-12-05 JP JP28993886A patent/JPS63143292A/en active Granted
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5332350A (en) * | 1976-09-06 | 1978-03-27 | Sutaa Denki Seizou Kk | Charging device with battery temperature detector |
| JPS5698496A (en) * | 1980-01-10 | 1981-08-07 | Nippon Kokan Kk <Nkk> | Chromate treating method of zinc alloy-electroplated steel plate |
| JPS5729597A (en) * | 1980-07-28 | 1982-02-17 | Teksid Spa | Long life thin plate for automobile body and method |
| JPS62278298A (en) * | 1985-08-28 | 1987-12-03 | Kawasaki Steel Corp | Chromated zn or zn alloy plated steel sheet and its production |
| JPS62107096A (en) * | 1985-11-01 | 1987-05-18 | Nippon Parkerizing Co Ltd | Surface treatment of galvanized steel sheet |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS63143292A (en) | 1988-06-15 |
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