JPS634916B2 - - Google Patents
Info
- Publication number
- JPS634916B2 JPS634916B2 JP59206784A JP20678484A JPS634916B2 JP S634916 B2 JPS634916 B2 JP S634916B2 JP 59206784 A JP59206784 A JP 59206784A JP 20678484 A JP20678484 A JP 20678484A JP S634916 B2 JPS634916 B2 JP S634916B2
- Authority
- JP
- Japan
- Prior art keywords
- plating
- corrosion
- film
- coating
- phase
- 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 46
- 229910000831 Steel Inorganic materials 0.000 claims description 30
- 239000010959 steel Substances 0.000 claims description 30
- 239000011248 coating agent Substances 0.000 claims description 24
- 238000000576 coating method Methods 0.000 claims description 24
- 229910045601 alloy Inorganic materials 0.000 claims description 19
- 239000000956 alloy Substances 0.000 claims description 19
- ZCDOYSPFYFSLEW-UHFFFAOYSA-N chromate(2-) Chemical compound [O-][Cr]([O-])(=O)=O ZCDOYSPFYFSLEW-UHFFFAOYSA-N 0.000 claims description 17
- 229910018605 Ni—Zn Inorganic materials 0.000 claims description 16
- 239000002131 composite material Substances 0.000 claims description 10
- 239000011651 chromium Substances 0.000 claims description 7
- 229910052759 nickel Inorganic materials 0.000 claims description 7
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 claims description 7
- 229910019142 PO4 Inorganic materials 0.000 claims description 6
- 239000010452 phosphate Substances 0.000 claims description 6
- 229910052804 chromium Inorganic materials 0.000 claims description 3
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 2
- 229920000642 polymer Polymers 0.000 claims description 2
- 230000008021 deposition Effects 0.000 claims 1
- 229920006254 polymer film Polymers 0.000 claims 1
- 238000005260 corrosion Methods 0.000 description 38
- 230000007797 corrosion Effects 0.000 description 37
- 239000010410 layer Substances 0.000 description 14
- 239000011701 zinc Substances 0.000 description 13
- 239000000463 material Substances 0.000 description 11
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 10
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 10
- 239000000126 substance Substances 0.000 description 10
- 229910052725 zinc Inorganic materials 0.000 description 10
- 239000003973 paint Substances 0.000 description 9
- 238000006243 chemical reaction Methods 0.000 description 7
- 238000007739 conversion coating Methods 0.000 description 7
- 230000006866 deterioration Effects 0.000 description 7
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 6
- 229910052742 iron Inorganic materials 0.000 description 5
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 4
- 229910052760 oxygen Inorganic materials 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- LRXTYHSAJDENHV-UHFFFAOYSA-H zinc phosphate Chemical compound [Zn+2].[Zn+2].[Zn+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O LRXTYHSAJDENHV-UHFFFAOYSA-H 0.000 description 4
- 229910000165 zinc phosphate Inorganic materials 0.000 description 4
- 229910001297 Zn alloy Inorganic materials 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000000049 pigment Substances 0.000 description 3
- 229920005989 resin Polymers 0.000 description 3
- 239000011347 resin Substances 0.000 description 3
- 150000003839 salts Chemical class 0.000 description 3
- 239000007921 spray Substances 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 229910001335 Galvanized steel Inorganic materials 0.000 description 2
- 229920000877 Melamine resin Polymers 0.000 description 2
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 description 2
- 229920000180 alkyd Polymers 0.000 description 2
- 239000010953 base metal Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- KRVSOGSZCMJSLX-UHFFFAOYSA-L chromic acid Substances O[Cr](O)(=O)=O KRVSOGSZCMJSLX-UHFFFAOYSA-L 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 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 description 2
- 239000008397 galvanized steel Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- XNGIFLGASWRNHJ-UHFFFAOYSA-N phthalic acid Chemical compound OC(=O)C1=CC=CC=C1C(O)=O XNGIFLGASWRNHJ-UHFFFAOYSA-N 0.000 description 2
- 238000006722 reduction reaction Methods 0.000 description 2
- 229910052718 tin Inorganic materials 0.000 description 2
- 239000004925 Acrylic resin Substances 0.000 description 1
- 229920000178 Acrylic resin Polymers 0.000 description 1
- 229910000967 As alloy Inorganic materials 0.000 description 1
- 239000004606 Fillers/Extenders Substances 0.000 description 1
- 239000004640 Melamine resin Substances 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 150000001450 anions Chemical class 0.000 description 1
- 230000002528 anti-freeze Effects 0.000 description 1
- LFYJSSARVMHQJB-QIXNEVBVSA-N bakuchiol Chemical compound CC(C)=CCC[C@@](C)(C=C)\C=C\C1=CC=C(O)C=C1 LFYJSSARVMHQJB-QIXNEVBVSA-N 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 239000004566 building material Substances 0.000 description 1
- 150000003841 chloride salts Chemical class 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 230000001419 dependent effect Effects 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
- 238000005516 engineering process Methods 0.000 description 1
- 229920006334 epoxy coating Polymers 0.000 description 1
- 239000003822 epoxy resin Substances 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- -1 fluoride ions Chemical class 0.000 description 1
- 238000005246 galvanizing Methods 0.000 description 1
- 239000004816 latex Substances 0.000 description 1
- 229920000126 latex Polymers 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000013011 mating Effects 0.000 description 1
- JDSHMPZPIAZGSV-UHFFFAOYSA-N melamine Chemical compound NC1=NC(N)=NC(N)=N1 JDSHMPZPIAZGSV-UHFFFAOYSA-N 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 229920000620 organic polymer Polymers 0.000 description 1
- UOURRHZRLGCVDA-UHFFFAOYSA-D pentazinc;dicarbonate;hexahydroxide Chemical compound [OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[Zn+2].[Zn+2].[Zn+2].[Zn+2].[Zn+2].[O-]C([O-])=O.[O-]C([O-])=O UOURRHZRLGCVDA-UHFFFAOYSA-D 0.000 description 1
- 229920000647 polyepoxide Polymers 0.000 description 1
- 229920000728 polyester Polymers 0.000 description 1
- 229920001225 polyester resin Polymers 0.000 description 1
- 239000004645 polyester resin Substances 0.000 description 1
- 229920005749 polyurethane resin Polymers 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 230000003449 preventive effect Effects 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 230000003746 surface roughness Effects 0.000 description 1
- 229920003002 synthetic resin Polymers 0.000 description 1
- 239000000057 synthetic resin Substances 0.000 description 1
- 125000000391 vinyl group Chemical group [H]C([*])=C([H])[H] 0.000 description 1
- 229920002554 vinyl polymer Polymers 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
- C25D11/38—Chromatising
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C22/78—Pretreatment of the material to be coated
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Mechanical Engineering (AREA)
- Electrochemistry (AREA)
- Chemical Treatment Of Metals (AREA)
- Other Surface Treatments For Metallic Materials (AREA)
- Laminated Bodies (AREA)
Description
（産業上の利用分野）
本発明は自動車々体、家電製品等の用途に使用
する表面処理鋼板に関するものである。
（従来の技術）
自動車々体材料の防錆対策および家電製品への
材料はここ数年間めざましい発展をとげ、多くの
表面処理鋼板が誕生した。これらの鋼板の一分野
としてNi−Zn合金めつき鋼板がある。従来のNi
−Zn合金めつき鋼はNiを９〜20％含む裸使用、
電着塗装主体の複合鋼板であつた。しかしながら
最上層に比較的厚膜の有機被覆膜を施して使用す
る場合の最適な表面処理鋼板についてはいまだ未
確立である。
本発明に関連する最近の公知技術としては、特
開昭58−210192号公報記載の９〜20％Ni−Zn（γ
相）合金めつき上にクロメート処理を施し、さら
に導電性塗料を有する鋼板、特開昭58−210190号
公報記載のγ相Ni−Zn合金めつき上に10〜40％
のFe−Zn合金めつきをし、その上にクロメート
さらに導電性塗料を有する表面処理鋼板がある。
いずれも最下層のNi含有率は９％以上のγ相め
つきである。
自動車等に用いられるNi−Zn合金めつき鋼板
は、北米、カナダ等の凍結防止剤散布を伴う自動
車々体の腐食にポイントをおいた材料設計がなさ
れてきた。これらの材料に要求される品質は高濃
度の塩化物が存在する腐食の激しい環境に対する
耐食性である。この様な環境下では、亜鉛めつき
の場合、亜鉛の溶食速度が速すぎるので、めつき
の電位を鉄に近づけためつきが必要である。しか
しながら、温暖な通常の環境下では亜鉛自身の腐
食は塩基性炭酸亜鉛の緻密な腐食生成物で覆れ、
腐食速度は緩かである。
このようにめつきの品質設計は実用的な環境下
で決定されるべきである。特に有機被覆された鋼
板の腐蝕は塗膜の傷部からの腐食にポイントを置
くべきであり、塗膜、めつき地鉄からなるセルの
電気化学的見地を入れた表面処理鋼板が必要であ
る。
（発明が解決しようとする問題点）
最上層に有機高分子被膜を有するめつき鋼板の
塗膜下腐食は、Ni含有率および化成処理被膜の
依存度が大きい。
化成処理被膜はNi含有率に関連があり、高Ni
含有率の合金めつきは表面が不働態化し易く、ク
ロメート被膜やリン酸塩被膜が形成し難く、不均
一な被膜が形成し易い。又、Ni含有率に比例し
てめつき皮膜が硬く、加工および腐食によりめつ
き層にクラツクが生成し、比較的マイルドな環境
下では腐食が孔食的に進行し易い原因となる。
本発明の目的は、一般的な環境下で使用される
自動車材料、比較的マイルドな環境下で使用され
る家電材料あるいは建材々料に対して最適な複合
めつき鋼板を提供しようとするものである。
（問題点を解決するための手段、作用）
本発明に係るめつき鋼板は、地鉄上に限定され
た組成の単相のNi−Zn合金めつきを有し、その
上に化成皮膜さらに有機被膜を有する３層構造か
ら成つている。すなわち、本発明の要旨は、Ni
を重量で１％以上から３％未満まで含む単相の
Ni−Zn合金めつき上に化成処理皮膜を有し、更
にその上に高分子被膜を有することを特徴とする
耐久性の優れた複合めつき鋼板である。
第１層のNi−Zn合金めつきはNiを１％以上３
％未満を含む単相の合金めつきである。本発明の
合金めつきはＸ線回析でγ相に相当するピークは
なく、η相である。Ni1％未満では亜鉛と同様に
過防食であり、塗膜が剥離し易い。Ni3％以上の
場合は儀牲防食能が弱く、孔食が発生し、更に酸
素濃淡電池の作用で傷部近傍で塗膜下腐食が生じ
易い。
めつき層中のNiを１〜３％未満に制御するこ
とにより、めつき層は純亜鉛の如き優れた加工性
を有し、クラツク等のメツキ欠陥が生じない。
又、クロメート処理に対してはNi含有率１〜３
％未満が最も活性な状態にあり、極めて短時間に
均一なクロメート処理やリン酸塩処理被膜を形成
させることが出来る。
Ni以外の合金成分は、亜鉛より貴な金属は0.5
％以下に抑える。0.5％超ではNiの高含有率成分
と同様な劣化を示すためである。Ni以外の合金
成分としては、Fe、Co、Cr、Sn、Mnが性能向
上に効果がある。
めつき量は10〜50ｇ／m2である。10ｇ／m2未満
ではピンホール等のめつき欠陥が発生する確率が
高く、厚めつきによつて解決できる。50ｇ／m2超
ではめつき表面粗度および密着性、特に経済的な
理由から好ましくない。
第１図に実施例１に基づく本発明に関する複合
めつき鋼板の国内屋外暴露試験における腐食およ
び劣化とめつき層中のNi含有率の関係を示した。
図から明らかな如く、実際の屋外暴露では高Ni
含有率は必ずしも耐食性が向上せず、むしろ低
Ni含有率の亜鉛めつき材が良い。このメカニズ
ムについては酸素濃淡電池の形成によるものと考
えられる。又、１％未満のNi含有率は塗膜の剥
離が大きい。
断面部からの観察では、第２図に示すような腐
食形態である。第２図Ａは複合めつき鋼板の断面
構成と腐蝕反応を示したものである。アノード反
応はＡで示されるZn→Zn2+＋2e、Ni→Ni2+＋2e
およびFe→Fe2+＋2e、カソード反応はＣで示さ
れる酸素の還元反応１／２O2＋H2O＋2e→2OH-で
ある。
第２図Ｂ〜Ｄは屋外暴露３年後の断面図で、め
つき層がＢは純亜鉛めつき、Ｃは12％Ni−Zn合
金めつき、Ｄは本発明（Ni2％の例）である。Ｂ
は亜鉛と塗膜の界面で水平方向に腐食が進み、塗
膜が浮いている。Ｃは地鉄の孔食および内部の塗
膜下でめつきが腐食し、塗膜がふくれている。Ｃ
は傷部のめつき塗膜界面で一部めつきが腐食して
いるのみである。
第２層の化成皮膜は、電解還元して析出させた
電解クロメートおよびリン酸塩被膜である。電解
クロメートは無水クロム酸とアニオン、例えば硫
酸イオン、リン酸イオン、フツ素イオンを主成分
とするクロメート液中で、該めつき鋼板を陰極と
して電解処理したのちただちに水洗し、乾燥して
３価クロムを主成分とするクロメート被膜を形成
させる。
クロメート被膜の付着量は、Crとして10〜150
mg／m2である。10mg／m2未満では耐食性が不充分
であり、塗膜とめつき界面の腐食が不充分とな
る。又150mg／m2では、クロメート被膜自身が加
工により破壊し易く、密着性が不充分である。
電解クロメートの好ましい範囲は、Crとして
20〜70mg／m2が望しい。リン酸塩皮膜の構成はリ
ン酸亜鉛（ホーパイト）あるいはリン酸亜鉛、鉄
（ホスフオフイライト）いずれでも良い。付着量
は１〜２ｇ／m2である。必要によりリン酸塩皮膜
上にＴ、Cr10mg／m2以下のクロム酸処理を施す
場合も本発明に含まれる。
第３層は有機被膜である。この層はプライマ
ー、仕上げ塗装の単独又は複層から構成されてい
る。塗膜の構成はビヒクルがエポキシ樹脂、フタ
ル酸樹脂、ビニル樹脂、メラミン樹脂、ポリエス
テル樹脂、スチレン樹脂、アクリル樹脂、アルキ
ツド樹脂、ポリウレタン樹脂、合成樹脂ラテツク
スの単独又は変性した樹脂を用いる。塗膜には防
錆顔料、着色剤、体質顔料からなる顔料および必
要により金属粉末も含まれる。塗膜厚みは１〜
20μである。望ましくは５〜10μの厚みが加工性
耐食性、生産性でバランスのとれた膜厚である。
実施例 １
硫酸浴（Zn2+40ｇ／、（NH4）2SO4100ｇ／
、Ni2+0、１、２、３、５、７、10、20、30
ｇ／）で浴温60℃、流速1.5ｍ／sec、電流密度
100A／ｄm2にて電気めつきを行つた。つづいて、
CrO3／H2SO4＝40／10ｇ／浴中で陰極電解に
よりクロメート被膜をT.Cr量として30mg／m2付
着させ、その後メラミンアルキツド樹脂（白）塗
料を20μ塗装し、130℃、５分間焼付け硬化して
本発明および比較鋼板を作成した。本発明のめつ
きはＸ線曲折で全てη相の単相であつた。これら
の材料を千葉県地区に屋外暴露し、３年経過後複
合鋼板の腐食を観察評価した。結果を第１表およ
び第１図に示す。
第１表Ａ、Ｂは１％未満のNi−Zn合金めつき
組成のもので、屋外暴露では塗膜剥離、塩水噴霧
では腐食による剥離、が生じている。Ｃ〜Ｆは本
発明材料で、塩水噴霧では劣化幅が激しいが、屋
外暴露では１mm以下である。Ｇ〜ｉはNiを３％
以上含む比較材で、塩水噴霧では非常に優れた防
食能を示している。しかし、屋外暴露では傷付部
からふくれが生じており、ふくれの下には腐蝕生
成物が形成している。
(Industrial Application Field) The present invention relates to a surface-treated steel sheet used for automobile bodies, home appliances, and the like. (Prior Art) Rust prevention measures for automobile body materials and materials for home appliances have made remarkable progress in recent years, and many surface-treated steel sheets have been created. One category of these steel sheets is Ni-Zn alloy plated steel sheets. Conventional Ni
-Zn alloy plated steel is used bare steel containing 9 to 20% Ni,
It was a composite steel plate mainly coated with electrodeposition. However, the optimum surface-treated steel sheet for use with a relatively thick organic coating on the top layer has not yet been established. As a recent known technology related to the present invention, 9 to 20% Ni-Zn (γ
Phase) Steel plate with chromate treatment on alloy plating and conductive paint, 10 to 40% on γ phase Ni-Zn alloy plating described in JP-A-58-210190.
There is a surface-treated steel sheet that is coated with Fe-Zn alloy and coated with chromate and conductive paint.
In both cases, the Ni content in the bottom layer is 9% or more and has a γ phase. Ni-Zn alloy plated steel sheets used in automobiles and the like have been designed with a focus on corrosion of automobile bodies that are exposed to antifreeze spraying in North America, Canada, and other countries. The quality required of these materials is corrosion resistance in highly corrosive environments where high concentrations of chlorides are present. Under such an environment, in the case of galvanizing, the corrosion rate of zinc is too fast, so it is necessary to apply a plating potential close to that of iron. However, under normal warm environments, the corrosion of zinc itself is covered with a dense corrosion product of basic zinc carbonate.
Corrosion rate is slow. In this way, plating quality design should be determined under practical circumstances. In particular, when it comes to corrosion of organically coated steel sheets, emphasis should be placed on corrosion from scratches in the paint film, and surface-treated steel sheets that take into account the electrochemical aspects of the cells consisting of the paint film and the plated base metal are required. . (Problems to be Solved by the Invention) Corrosion under the coating of a plated steel sheet having an organic polymer coating on the top layer is highly dependent on the Ni content and the chemical conversion coating. Chemical conversion coatings are related to Ni content, and high Ni
In the case of alloy plating with a high content, the surface tends to become passivated, making it difficult to form a chromate film or a phosphate film, and easily forming a non-uniform film. In addition, the plating film is hard in proportion to the Ni content, and cracks are generated in the plating layer due to processing and corrosion, which causes corrosion to easily progress in the form of pitting corrosion in a relatively mild environment. The purpose of the present invention is to provide a composite galvanized steel sheet that is optimal for automobile materials used in general environments, home appliance materials, and building materials used in relatively mild environments. be. (Means and effects for solving the problem) The plated steel sheet according to the present invention has a single-phase Ni-Zn alloy plating with a limited composition on the base steel, and further has a chemical conversion coating and an organic It consists of a three-layer structure with a coating. That is, the gist of the present invention is that Ni
A single phase containing from 1% to less than 3% by weight of
This is a composite plated steel sheet with excellent durability, characterized by having a chemical conversion coating on the Ni-Zn alloy plating, and further having a polymer coating on top of that. The first layer Ni-Zn alloy plating contains 1% or more Ni3
It is a single-phase alloy plating containing less than %. The alloy plating of the present invention has no peak corresponding to the γ phase in X-ray diffraction, but is an η phase. If Ni is less than 1%, it will not provide excessive corrosion protection like zinc, and the coating film will easily peel off. When the Ni content is 3% or more, the sacrificial corrosion protection ability is weak, pitting corrosion occurs, and furthermore, under-film corrosion tends to occur near the scratched area due to the action of the oxygen concentration battery. By controlling the Ni content in the plating layer to less than 1 to 3%, the plating layer has excellent workability similar to that of pure zinc, and plating defects such as cracks do not occur.
In addition, for chromate treatment, Ni content is 1 to 3.
% is in the most active state and can form a uniform chromate treatment or phosphate treatment film in an extremely short time. Alloy components other than Ni are 0.5 for metals nobler than zinc.
% or less. This is because if it exceeds 0.5%, it shows the same deterioration as a high Ni content component. As alloy components other than Ni, Fe, Co, Cr, Sn, and Mn are effective in improving performance. The amount of plating is 10 to 50 g/m 2 . If it is less than 10 g/m 2 , there is a high probability that plating defects such as pinholes will occur, which can be solved by thicker plating. If it exceeds 50 g/m 2 , it is unfavorable from the viewpoint of plating surface roughness and adhesion, especially for economical reasons. FIG. 1 shows the relationship between corrosion and deterioration in a domestic outdoor exposure test of a composite plated steel sheet according to the present invention based on Example 1, and the Ni content in the plated layer.
As is clear from the figure, in actual outdoor exposure, high Ni
The content does not necessarily improve corrosion resistance, but rather lowers it.
Galvanized material with Ni content is good. This mechanism is thought to be due to the formation of an oxygen concentration cell. Further, if the Ni content is less than 1%, the coating film will peel off significantly. When observed from a cross section, the corrosion pattern is as shown in FIG. FIG. 2A shows the cross-sectional structure and corrosion reaction of a composite plated steel plate. The anodic reaction is shown by A: Zn→Zn 2+ +2e, Ni→Ni 2+ +2e
and Fe→Fe 2+ +2e, and the cathode reaction is a reduction reaction of oxygen represented by C, 1/2O 2 +H 2 O+2e→2OH - . Figure 2 B to D are cross-sectional views after 3 years of outdoor exposure, and the plating layer B is pure zinc plating, C is 12% Ni-Zn alloy plating, and D is the present invention (example of 2% Ni). be. B
Corrosion progresses horizontally at the interface between the zinc and the paint film, causing the paint film to float. In C, there is pitting corrosion on the base metal and corrosion of the plating under the internal paint film, causing the paint film to swell. C
The plating is only partially corroded at the interface of the plating film in the scratched area. The second layer of chemical conversion coating is an electrolytic chromate and phosphate coating deposited by electrolytic reduction. Electrolytic chromate is electrolytically treated in a chromate solution containing anhydrous chromic acid and anions such as sulfate ions, phosphate ions, and fluoride ions, using the plated steel plate as a cathode, immediately washed with water, and dried to form trivalent chromates. A chromate film containing chromium as the main component is formed. The amount of chromate film deposited is 10 to 150 as Cr.
mg/ m2 . If it is less than 10 mg/m 2 , the corrosion resistance will be insufficient, and the corrosion of the coating film and the mating interface will be insufficient. Moreover, at 150 mg/m 2 , the chromate film itself is easily destroyed by processing, resulting in insufficient adhesion. The preferred range of electrolytic chromate is as Cr
20-70mg/ m2 is desirable. The structure of the phosphate film may be either zinc phosphate (hopite) or zinc phosphate and iron (phosphophylrite). The amount of adhesion is 1 to 2 g/m 2 . The present invention also includes the case where the phosphate film is treated with chromic acid at a concentration of T and Cr of 10 mg/m 2 or less, if necessary. The third layer is an organic coating. This layer consists of a single layer or a combination of a primer and a finishing coat. The coating film is constructed by using an epoxy resin, a phthalic acid resin, a vinyl resin, a melamine resin, a polyester resin, a styrene resin, an acrylic resin, an alkyd resin, a polyurethane resin, or a synthetic resin latex as the vehicle, either alone or in a modified form. The coating film also contains a pigment consisting of a rust preventive pigment, a coloring agent, an extender pigment, and metal powder if necessary. The coating thickness is 1~
It is 20μ. A thickness of 5 to 10 μm is preferably a film thickness that is well-balanced in terms of workability, corrosion resistance, and productivity. Example 1 Sulfuric acid bath (Zn 2+ 40g/, (NH 4 ) 2 SO 4 100g/
, Ni 2+ 0 , 1, 2, 3, 5, 7, 10, 20, 30
g/), bath temperature 60℃, flow rate 1.5m/sec, current density
Electroplating was carried out at 100A/ dm2 . Continuing,
CrO 3 /H 2 SO 4 = 40/10 g/A chromate film was deposited at 30 mg/m 2 of T.Cr by cathodic electrolysis in a bath, and then 20μ of melamine alkyd resin (white) paint was applied, and the temperature was 130°C. The steel plates of the present invention and comparative steel plates were prepared by baking and hardening for 5 minutes. The plating of the present invention was found to be entirely in a single η phase by X-ray bending. These materials were exposed outdoors in Chiba Prefecture, and after three years, the corrosion of the composite steel plates was observed and evaluated. The results are shown in Table 1 and Figure 1. Table 1 A and B have Ni-Zn alloy plating compositions of less than 1%, and the coating peeled off when exposed outdoors and peeled off due to corrosion when exposed to salt water spray. C to F are materials of the present invention, and the extent of deterioration is severe when exposed to salt water spray, but the extent of deterioration is less than 1 mm when exposed outdoors. G~i contains 3% Ni
The comparative materials listed above show very good anti-corrosion performance when exposed to salt spray. However, when exposed outdoors, blisters appear from the damaged areas, and corrosion products form beneath the blisters.
【表】
実施例 ２
硫酸浴よりNi2％を含む単相のNi−Zn合金め
つきを15ｇ／m2メツキし、リン酸亜鉛皮膜1.5
ｇ／m2した後ポリエステル（白）塗膜を15μ行つ
た。人工傷を入れた後、東京地区の屋外に暴露５
年後の評価は劣化幅１mm以下で良好であつた。
実施例 ３
硫酸浴からNi1.5％、Fe0.3％含む単相のNi−
Zn合金めつきを25ｇ／m2めつきし、リン酸亜鉛
の鉄皮膜を1.5ｇ／m2形成させたのち、エポキシ
塗膜を5μ塗装した。その後プレス10mm高さの深
絞り加工後、浴室内にて暴露３年後、錆は認めら
れなかつた。
実施例 ４
実施３のFe0.3％の代りにCo0.1％、Cr0.02％、
Sn0.1％を含む３種類の単相めつき上に同様の処
理をして複合めつき鋼板を作成し、浴室内の暴露
を３年行つた結果、錆は認められなかつた。
（発明の効果）
本発明は普通の実際の腐食環境下において耐久
性のある複合めつき鋼板を提供するものである
が、その他以下の如き効果がある。
めつきの管理が容易で作業性が良く、歩留り
が高い。γ相のめつきは浴の管理、電解条件等
製造面での制御に多大の設備と労力を必要とす
る。本発明は、低Ni含有率のため極めて容易
である。
クロメートの汎用性がある。従来のγ相中心
のNi−Zn合金めつきは、化成性の点で制限が
あつた。低Ni−Zn合金めつきは殆んど亜鉛と
同様の化成性を有する。
めつき皮膜が単相でしかもγ相を含まないた
め、加工による劣化が少く、広い用途が期待出
来る。[Table] Example 2 Single-phase Ni-Zn alloy plating containing 2% Ni was plated at 15 g/ m2 from a sulfuric acid bath, and a zinc phosphate film of 1.5
g/m 2 and then a 15 μm polyester (white) coating was applied. Exposure to the outdoors in the Tokyo area after making an artificial wound 5
The evaluation after a year was good, with the width of deterioration being less than 1 mm. Example 3 Single-phase Ni− containing 1.5% Ni and 0.3% Fe from a sulfuric acid bath
Zn alloy plating was applied at 25 g/m 2 , and an iron film of zinc phosphate was formed at 1.5 g/m 2 , and then a 5μ epoxy coating was applied. Thereafter, after deep drawing to a height of 10 mm using a press, no rust was observed after 3 years of exposure in the bathroom. Example 4 Instead of Fe0.3% in Example 3, Co0.1%, Cr0.02%,
Composite plated steel sheets were created by applying the same treatment to three types of single-phase plating containing 0.1% Sn, and after being exposed in a bathroom for three years, no rust was observed. (Effects of the Invention) The present invention provides a composite galvanized steel sheet that is durable under normal actual corrosive environments, and also has the following effects. Easy to control plating, good workability, and high yield. γ-phase plating requires a large amount of equipment and labor to control manufacturing aspects such as bath management and electrolytic conditions. The present invention is extremely easy due to the low Ni content. Chromate has versatility. Conventional Ni-Zn alloy plating centered on the γ phase has been limited in terms of chemical formability. Low Ni-Zn alloy plating has almost the same formability as zinc. Since the plating film is single-phase and does not contain a γ phase, it is less susceptible to deterioration during processing and can be expected to have a wide range of uses.
第１図は、実施例１に基づく屋外暴露後の傷付
け部からの劣化幅とめつき層中のNi（％）の関係
を本発明材、比較材について示したものである。
第２図は屋外暴露後の断面図である。亜鉛の場合
は有機被膜とめつきの界面で剥離が生じている。
高Niめつきの場合は地鉄の孔食および酸素濃淡
電池形成によるめつきの腐食によりふくれが生じ
ている。Ａは腐食の生ずる場所と腐食反応（Ａは
アノード反応、Ｃはカソード反応）を示す。Ｂは
純亜鉛の上に化成皮膜と有機皮膜の腐蝕状態、Ｃ
はγ相の12％Ni−Zn合金めつき被膜上に化成皮
膜と有機被膜を有する鋼板の腐蝕状態、Ｄは本発
明による２％Ni−Zn合金単相よりなるめつき上
に化成皮膜と有機皮膜を有する鋼板の腐蝕を示し
たものである。Ｂ，Ｃ，Ｄともめつき上の化成皮
膜の種類および有機被膜の種類は同一である。
FIG. 1 shows the relationship between the width of deterioration from the scratched part after outdoor exposure and Ni (%) in the plating layer for the inventive material and the comparative material based on Example 1.
FIG. 2 is a cross-sectional view after outdoor exposure. In the case of zinc, peeling occurs at the interface between the organic film and the plating.
In the case of high Ni plating, blistering occurs due to pitting corrosion of the base steel and corrosion of the plating due to the formation of oxygen concentration cells. A indicates the location where corrosion occurs and the corrosion reaction (A is an anode reaction, C is a cathode reaction). B is the corrosion state of the chemical coating and organic coating on pure zinc, C
is the corrosion state of a steel plate having a chemical conversion coating and an organic coating on a γ-phase 12% Ni-Zn alloy plating coating, and D is the corrosion state of a steel plate having a chemical conversion coating and an organic coating on a plating consisting of a single-phase 2% Ni-Zn alloy according to the present invention. This figure shows the corrosion of a steel plate with a coating. The type of chemical conversion film and the type of organic film on the plating are the same for B, C, and D.
Claims (1)
めつき量10〜50ｇ／m2の単相のNi−Zn合金めつ
き被膜上にクロム付着量10〜130mg／m2の電解ク
ロメート処理被膜を有し、更にその上に高分子被
膜を有することを特徴とする耐久性の優れた複合
めつき鋼板。 ２ Niを重量で１％以上から３％未満まで含む
めつき量10〜50ｇ／m2の単相のNi−Zn合金めつ
き被膜上に１〜２ｇ／m2のリン酸塩被膜を有し、
更にその上に高分子被膜を有することを特徴とす
る耐久性の優れた複合めつき鋼板。[Claims] 1. Chromium deposition amount 10-130 mg/ m2 on a single-phase Ni-Zn alloy plating film containing 1% or more to less than 3% Ni by weight, plating amount 10-50 g/m2 2. A composite plated steel sheet with excellent durability, characterized by having an electrolytic chromate treatment film as described above, and further having a polymer film on top of the electrolytic chromate treatment film. 2 Having a phosphate coating of 1 to 2 g/m 2 on a single-phase Ni-Zn alloy plating coating with a plating amount of 10 to 50 g/m 2 containing Ni from 1% to less than 3% by weight. ,
A composite plated steel sheet with excellent durability characterized by having a polymer coating thereon.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP20678484A JPS6184381A (en) | 1984-10-02 | 1984-10-02 | Composite plated steel sheet having superior durability |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP20678484A JPS6184381A (en) | 1984-10-02 | 1984-10-02 | Composite plated steel sheet having superior durability |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6184381A JPS6184381A (en) | 1986-04-28 |
| JPS634916B2 true JPS634916B2 (en) | 1988-02-01 |
Family
ID=16529034
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP20678484A Granted JPS6184381A (en) | 1984-10-02 | 1984-10-02 | Composite plated steel sheet having superior durability |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6184381A (en) |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS55110792A (en) * | 1979-02-15 | 1980-08-26 | Sumitomo Metal Ind Ltd | Surface treated steel plate |
| JPS55110781A (en) * | 1979-02-15 | 1980-08-26 | Sumitomo Metal Ind Ltd | Surface treated steel plate with good spot weldability |
| JPS56130477A (en) * | 1980-03-13 | 1981-10-13 | Sumitomo Metal Ind Ltd | Surface treated steel plate |
| JPS58210192A (en) * | 1982-05-29 | 1983-12-07 | Sumitomo Metal Ind Ltd | Weldable coated steel plate |
-
1984
- 1984-10-02 JP JP20678484A patent/JPS6184381A/en active Granted
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS55110792A (en) * | 1979-02-15 | 1980-08-26 | Sumitomo Metal Ind Ltd | Surface treated steel plate |
| JPS55110781A (en) * | 1979-02-15 | 1980-08-26 | Sumitomo Metal Ind Ltd | Surface treated steel plate with good spot weldability |
| JPS56130477A (en) * | 1980-03-13 | 1981-10-13 | Sumitomo Metal Ind Ltd | Surface treated steel plate |
| JPS58210192A (en) * | 1982-05-29 | 1983-12-07 | Sumitomo Metal Ind Ltd | Weldable coated steel plate |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6184381A (en) | 1986-04-28 |
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