JPH0765218B2 - Chromate treated zinc-chromium electroplated steel sheet - Google Patents
Chromate treated zinc-chromium electroplated steel sheetInfo
- Publication number
- JPH0765218B2 JPH0765218B2 JP63001187A JP118788A JPH0765218B2 JP H0765218 B2 JPH0765218 B2 JP H0765218B2 JP 63001187 A JP63001187 A JP 63001187A JP 118788 A JP118788 A JP 118788A JP H0765218 B2 JPH0765218 B2 JP H0765218B2
- Authority
- JP
- Japan
- Prior art keywords
- chromate
- steel sheet
- layer
- corrosion resistance
- chromium
- 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 - Fee Related
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D3/00—Electroplating: Baths therefor
- C25D3/02—Electroplating: Baths therefor from solutions
- C25D3/56—Electroplating: Baths therefor from solutions of alloys
- C25D3/565—Electroplating: Baths therefor from solutions of alloys containing more than 50% by weight of zinc
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D15/00—Electrolytic or electrophoretic production of coatings containing embedded materials, e.g. particles, whiskers, wires
- C25D15/02—Combined electrolytic and electrophoretic processes with charged materials
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
- C25D5/10—Electroplating with more than one layer of the same or of different metals
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
- C25D5/60—Electroplating characterised by the structure or texture of the layers
- C25D5/625—Discontinuous layers, e.g. microcracked layers
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Electroplating Methods And Accessories (AREA)
- Chemical Treatment Of Metals (AREA)
Description
【発明の詳細な説明】 ［産業上の利用分野］ 本発明は、自動車、家電、建材等に使用される耐食性に
優れた亜鉛−クロム系電気めっき鋼板、特にクロメート
処理を施してなる電気めっき鋼板に関するものである。DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a zinc-chromium electroplated steel sheet having excellent corrosion resistance, which is used for automobiles, home appliances, building materials, etc., in particular, an electroplated steel sheet which has been subjected to chromate treatment. It is about.
［従来の技術］ 亜鉛めっきまたは亜鉛系合金めっき鋼板は、その優れた
耐食性が評価され、自動車、家電製品、屋外機器、建材
等に汎用されている。しかしその耐食性も十分ではな
く、亜鉛系めっき鋼板にクロメート処理を行う防錆鋼板
を種々開発されてきた。[Prior Art] Zinc-plated or zinc-based alloy-plated steel sheets have been evaluated for their excellent corrosion resistance and are widely used in automobiles, home appliances, outdoor equipment, building materials, and the like. However, its corrosion resistance is not sufficient, and various rust-preventing steel sheets in which a zinc-based plated steel sheet is subjected to chromate treatment have been developed.
［発明が解決しようとする課題］ しかし、この従来の防錆鋼板のいずれもその耐食性は、
下地のめっき層に負うところが大きく、上層のクロメー
ト層もミクロ的に均一ではないため、その欠陥部やさら
にまた、プレス加工後のクラック部や疵部から腐食が広
がり、その耐食性は十分ではなかった。[Problems to be Solved by the Invention] However, the corrosion resistance of any of these conventional rust-preventing steel sheets is
The underlying plating layer is largely responsible, and the upper chromate layer is not microscopically uniform, so the corrosion spreads from the defective parts and also from the cracks and scratches after pressing, and its corrosion resistance was not sufficient. .
本発明は上記問題点を解決し、耐食性を飛跳的に向上さ
せた電気めっき鋼板を提供するものである。The present invention solves the above-mentioned problems and provides an electroplated steel sheet with dramatically improved corrosion resistance.
［課題を解決するための手段］ 上記目的を達成するための本発明は、クロメート処理め
っき鋼板において、下層がCr5〜40％含有する亜鉛−ク
ロム系めっき層からなり、表層がクロメート皮膜からな
ることを特徴とするクロメート処理を施した亜鉛−クロ
ム系電気めっき鋼板である。[Means for Solving the Problems] The present invention for achieving the above object is, in a chromate-treated plated steel sheet, a lower layer comprising a zinc-chromium-based plating layer containing 5 to 40% of Cr and a surface layer comprising a chromate film. Is a zinc-chromium electroplated steel sheet that has been subjected to a chromate treatment.
［作用］ 先ず、Zn−Crめっき層の特徴について述べる。Crは、Zn
と共析することによって不働態化せず、活性状態を維持
しつつ、Znとともに鋼素地に対する犠牲防食作用に加担
する。更にCrの腐食生成物が難溶性であり、腐食が進行
している局部に保持皮膜を沈積するので耐食性が極めて
高くなる。[Operation] First, the features of the Zn-Cr plated layer will be described. Cr is Zn
By co-depositing with, it does not passivate and maintains an active state, and also takes part in sacrificial anticorrosion action on the steel base together with Zn. Further, the corrosion product of Cr is hardly soluble, and since the holding film is deposited on the part where the corrosion is progressing, the corrosion resistance becomes extremely high.
ゆえに、Zn−Crめっき層の上層にあらかじめ保護皮膜と
なるクロメート層を形成させることによって、その耐食
性は相乗作用により極めて高いものとなる。Therefore, by forming a chromate layer to be a protective film in advance on the Zn-Cr plated layer, its corrosion resistance becomes extremely high due to a synergistic effect.
即ち、腐食環境に曝されると、クロメート層の欠陥を通
じて下地のめっき層が先ず腐食を受ける。従来のめっき
では、めっき層の腐食物が保護膜とならないで、この欠
陥部を機転に腐食が拡大され、最終的には鋼素地が腐食
を受け赤錆が発錆する。That is, when exposed to a corrosive environment, the underlying plating layer is first corroded through defects in the chromate layer. In conventional plating, corrosive substances in the plating layer do not serve as a protective film, and this defective portion is used as a mechanism to expand corrosion, and eventually the steel substrate is corroded and red rust occurs.
Crの腐食生成物は、沈積してバリアーとなり、いわゆる
錆詰り作用によって、水、酸素、塩素イオン等の腐食因
子の侵入を防止するので腐食の進行を妨げるのである。Corrosion products of Cr are deposited as a barrier and prevent the penetration of corrosion factors such as water, oxygen, and chlorine ions by the so-called rust clogging action, thus hindering the progress of corrosion.
プレス等によって加工を施した成形品では、鋼素地まで
貫通した亀裂が既に入っており、従来のクロメート処理
めっき鋼板では、クロメート層のバリアー効果が減殺さ
れることが致命的欠陥であった。Zn−Crめっき層は、こ
のような亀裂内部にも保護皮膜を沈積して腐食を停止さ
せる作用を有するのである。この作用は従来からクロメ
ート処理めっき鋼板の下地めっき層として使用されてい
たZn、Zn−Ni、Zn−Feめっき層では期待できないもので
ある。The molded product processed by pressing or the like already has cracks penetrating to the steel substrate, and in the conventional chromate-treated plated steel sheet, it was a fatal defect that the barrier effect of the chromate layer was diminished. The Zn-Cr plating layer has a function of depositing a protective film inside such cracks and stopping corrosion. This effect cannot be expected in the Zn, Zn-Ni, and Zn-Fe plating layers that have been conventionally used as the undercoating layer of chromate-treated plated steel sheets.
Zn−Crめっき層のCr含有量は、５〜40％が好ましい。５
％未満ではCrによる耐食性向上効果は若干認められるも
のの、十分ではない。40％を越えると、Crの耐食性向上
効果はあるが、加工時にめっき層が剥離し易くなる傾向
が現われ、実用上は不適である。The content of Cr in the Zn-Cr plated layer is preferably 5 to 40%. 5
If it is less than%, the effect of improving the corrosion resistance by Cr is slightly recognized, but it is not sufficient. If it exceeds 40%, the corrosion resistance of Cr is improved, but the plating layer tends to peel off during processing, which is not suitable for practical use.
なおZn、Cr以外に、Fe、Ni、Co、Mn、Sn、Sb、Al、Mo、
Ｗ、Ti、Si、Cu、Na、Mg、Ｐ、Ｏ、Ｃ、等が少量含有さ
れていても、本質的に本発明の効果は変らないものであ
る。めっき付着量としては、５〜50g/m2が適当である。In addition to Zn and Cr, Fe, Ni, Co, Mn, Sn, Sb, Al, Mo,
Even if a small amount of W, Ti, Si, Cu, Na, Mg, P, O, C, etc. is contained, the effect of the present invention is essentially unchanged. An appropriate coating amount is 5 to 50 g / m 2 .
めっき層の上に施されるクロメート層は、Zn−Crめっき
層が、Cr+6および／またはCr+3からなる酸性処理液との
反応性は比較的高いので、従来から公知の塗布型クロメ
ート処理、反応型クロメート処理および電解型クロメー
ト処理等はいずれも適用できる。The chromate layer applied on top of the plating layer has a relatively high reactivity with the acidic treatment liquid consisting of Cr +6 and / or Cr +3. Any of treatment, reactive chromate treatment, electrolytic chromate treatment and the like can be applied.
塗布型、反応型クロメート処理としてはCr+6、Cr+3の他
に無機コロイド類を添加するもの、りん酸等の酸類、ふ
っ化物類を添加するもの、あるいは水溶性ないしエマル
ジョン型の有機樹脂を添加するものが適用できる。For coating type and reactive type chromate treatment, addition of inorganic colloids in addition to Cr +6 and Cr +3 , addition of acids such as phosphoric acid, fluorides, or water-soluble or emulsion type organic resin Can be applied.
例えば、りん酸、ふっ化物を含む処理液としては、クロ
ム酸30g/、りん酸10g/、ふっ化チタンカリ4g/、
ふっ化ナトリウム0.5g/、シリカを含む処理液として
は、クロム酸50g/、うち３価のクロム40％、SiO2 100
g/がある。無機コロイド類としては、例えばSiO2、Al
2O3、TiO2、ZrO等のコロイド類、またはモリブデン酸、
タングステン酸、バナジン酸等の酸素酸およびその塩
類、またはめっきのZnと反応して難溶性塩をつくるりん
酸、ポリりん酸などのりん酸類、または加水分解などの
反応により難溶性塩をつくるケイふっ化物、チタンふっ
化物、りん酸塩などを１種類以上含むのものである。こ
れらコロイド類は、クロメート皮膜中に少量の６価のク
ロムを固定するうえで有効である。これら無機コロイド
類の添加量は添加物の種類によってことなるが、例えば
りん酸塩では１−200g/,SiO2では１−800g/であ
る。For example, as a treatment liquid containing phosphoric acid and fluoride, chromic acid 30 g /, phosphoric acid 10 g /, titanium fluoride fluoride 4 g /,
Treatment solution containing sodium fluoride 0.5g /, silica, chromic acid 50g /, trivalent chromium 40%, SiO 2 100
There is g /. Examples of the inorganic colloids include SiO 2 and Al
2 O 3 , TiO 2 , ZrO and other colloids, or molybdic acid,
Oxygen acids such as tungstic acid and vanadic acid and their salts, or phosphoric acid that reacts with Zn in plating to form sparingly soluble salts, phosphoric acid such as polyphosphoric acid, or silicic acid that forms sparingly soluble salts through reactions such as hydrolysis. It contains one or more kinds of fluoride, titanium fluoride, phosphate and the like. These colloids are effective in fixing a small amount of hexavalent chromium in the chromate film. The amount of these inorganic colloids added varies depending on the type of the additive, but is, for example, 1-200 g / for phosphate and 1-800 g / for SiO 2 .
なお場合によっては、アクリル樹脂等のクロメートに安
定に混合可能な有機樹脂を添加してもよい。In some cases, an organic resin that can be stably mixed with a chromate such as an acrylic resin may be added.
電解クロメート処理としては、クロム酸に加えて硫酸、
りん酸、ハロゲンイオン等を添加するもの、あるいは／
およびSiO2、Al2O3等の無機コロイド類を添加するも
の、Zn、Co、Mg等のカチオンを添加するものも適用でき
る。通常陰極電解を施すが、陽極電解、交番電解を付加
することもできる。For electrolytic chromate treatment, in addition to chromic acid, sulfuric acid,
Addition of phosphoric acid, halogen ions, or
Also applicable are those to which inorganic colloids such as SiO 2 and Al 2 O 3 are added, and those to which cations such as Zn, Co and Mg are added. Usually, cathodic electrolysis is performed, but anodic electrolysis and alternating electrolysis can be added.
クロメート層の皮膜層は、クロムとして５〜500mg/m2が
適当である。5mg/m2未満では耐食性改善効果が不十分で
あり、500mg/m2を越えると溶接性が悪化し、実用上好ま
しくない。The chromate layer is preferably 5 to 500 mg / m 2 as chromium. If it is less than 5 mg / m 2 , the effect of improving the corrosion resistance is insufficient, and if it exceeds 500 mg / m 2 , the weldability deteriorates, which is not preferable in practice.
［実施例］ 本発明の実施例を比較例ととも表１に挙げる。[Examples] Examples of the present invention are shown in Table 1 together with comparative examples.
注１） めっき条件 Zn2+イオン56g/、Cr3+イオン44g/、Na+イオン15g/
を硫酸塩として建浴、ポリエチレングリコール（分子
量1500）を1g/添加したpH＝2.0、50℃のめっき浴を用
いて、冷延鋼板にめっき液流速60m/分、電流密度100A/d
m2で表１に示す実施例１のめっき鋼板を製造した。他の
実施例はそれぞれ条件を変えてCr含有量を変化させた。Note 1) Plating conditions Zn 2+ ion 56g /, Cr 3+ ion 44g /, Na + ion 15g /
Is used as a sulfate, a plating bath containing 1 g / polyethylene glycol (molecular weight 1500) at pH = 2.0 and 50 ° C is used, the flow rate of the plating solution is 60 m / min, and the current density is 100 A / d.
The plated steel sheet of Example 1 shown in Table 1 was produced in m 2 . In other examples, the Cr content was changed by changing the conditions.
なお、比較例のZn−Ni、Zn−Feめっきは周知の条件でめ
っきを施した。The Zn-Ni and Zn-Fe platings of Comparative Example were plated under known conditions.
注２） クロメート処理条件 （ａ）塗布型クロメート クロム酸50g/うちCr3+40％、SiO2コロイド100g/か
らなる処理液にめっき板を浸漬、エアーワイプ法で塗布
し、100℃、１分で乾燥した。クロメートの付着量は処
理液の希釈率とエアーワイプにより調節した。Note 2) Chromate treatment conditions (a) Coating-type chromate Chromic acid 50 g / Cr 3+ 40%, SiO 2 colloid 100 g / A plating plate is dipped in a treatment liquid and applied by the air wipe method at 100 ° C for 1 minute. Dried in. The amount of chromate adhered was adjusted by the dilution ratio of the treatment liquid and the air wipe.
（ｂ）反応型クロメート クロム酸50g/、りん酸10g/、NaF0.5g/、K2TiF64g
/からなる処理液をめっき板にロールコーターで塗布
し、60℃で乾燥した。クロメートの付着量は処理液の希
釈率とロールコーターで調節した。(B) Reactive chromate Chromic acid 50 g /, phosphoric acid 10 g /, NaF 0.5 g /, K 2 TiF 6 4 g
The treatment liquid consisting of / was applied to the plated plate with a roll coater and dried at 60 ° C. The amount of chromate adhered was adjusted by the dilution ratio of the treatment liquid and a roll coater.
（ｃ）電解型クロメート ケロム酸50g/、硫酸0.4g/、りん酸20g/、炭酸亜
鉛11g/からなる処理液中3A/dm2でめっき板に陰極電解
し、水洗、乾燥した。クロメートの付着量はクーロン量
で調節した。(C) Electrolytic Chromate A plated plate was subjected to cathodic electrolysis at 3 A / dm 2 in a treatment liquid consisting of 50 g / of cheromic acid, 0.4 g / of sulfuric acid, 20 g / of phosphoric acid, and 11 g / of zinc carbonate, washed with water and dried. The amount of chromate attached was adjusted by the amount of Coulomb.
注３） 耐食性 JIS Z 2371に準拠した塩水噴霧試験で赤錆２％発生する
までの時間。Note 3) Corrosion resistance Time until 2% of red rust occurs in a salt spray test according to JIS Z 2371.
注４） 加工後耐食性 試験片を10％引張り加工した後、JIS Z 2371に準拠した
塩水噴霧試験をし、赤錆２％発生するまでの時間。Note 4) The time until 2% of red rust is generated after 10% tensile processing of the post-processing corrosion resistance test piece and a salt spray test according to JIS Z 2371.
［発明の効果］ 以上説明したごとく本発明は、従来のクロメート処理鋼
板の問題点であった耐食性を飛躍的に向上させることが
でき、高い耐食性を必要とする自動車、家電製品をはじ
め屋内外機器や建材などに広く利用することができる。 [Advantages of the Invention] As described above, the present invention can dramatically improve the corrosion resistance, which has been a problem of the conventional chromate-treated steel sheet, and has high corrosion resistance in automobiles, home appliances, and other indoor and outdoor equipment. It can be widely used as a building material.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 中山 元宏 愛知県東海市東海町５―３ 新日本製鐵株 式会社名古屋製鐵所内 (72)発明者 新井 勝利 愛知県東海市東海町５―３ 新日本製鐵株 式会社名古屋製鐵所内 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Motohiro Nakayama 5-3 Tokai-cho, Tokai-shi, Aichi Prefecture Nippon Steel Co., Ltd. Nagoya Steel Works (72) Inventor Satoru Arai 5 Tokai-cho, Tokai-shi, Aichi- 3 Inside Nippon Steel Works, Nippon Steel Co., Ltd.
Claims (1)
がCr5〜40％含有する亜鉛−クロム系めっき層からな
り、表層がクロメート皮膜からなることを特徴とするク
ロメート処理を施した亜鉛−クロム系電気めっき鋼板。1. A chromate-treated galvanized steel sheet, wherein the lower layer is a zinc-chromium-based plating layer containing 5 to 40% of Cr, and the surface layer is a chromate film. steel sheet.
Priority Applications (11)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63001187A JPH0765218B2 (en) | 1988-01-08 | 1988-01-08 | Chromate treated zinc-chromium electroplated steel sheet |
| DE88104874T DE3882769T2 (en) | 1987-03-31 | 1988-03-25 | Corrosion-resistant plated steel strip and process for its manufacture. |
| EP88104874A EP0285931B1 (en) | 1987-03-31 | 1988-03-25 | Corrosion resistant plated steel strip and method for producing same |
| US07/174,830 US4897317A (en) | 1987-03-31 | 1988-03-29 | Corrosion resistant Zn-Cr plated steel strip |
| AU13897/88A AU597163B2 (en) | 1987-03-31 | 1988-03-30 | Corrosion resistant plated steel strip and method for producing same |
| CA000562971A CA1336698C (en) | 1987-03-31 | 1988-03-30 | Corrosion resistant plated steel strip and method for producing same |
| KR1019880003622A KR910002186B1 (en) | 1987-03-31 | 1988-03-31 | Corrosion resistant zn-cr plated steel strip |
| US07/320,071 US4877494A (en) | 1987-03-31 | 1989-03-07 | Corrosion resistant plated steel strip and method for producing same |
| CA000616732A CA1336700C (en) | 1987-03-31 | 1993-09-21 | Corrosion resistant plated steel strip and method for producing same |
| CA000616731A CA1336699C (en) | 1987-03-31 | 1993-09-21 | Corrosion resistant plated steel strip and method for producing same |
| CA000616830A CA1337054C (en) | 1987-03-31 | 1994-03-07 | Corrosion resistant plated steel strip and method for producing same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63001187A JPH0765218B2 (en) | 1988-01-08 | 1988-01-08 | Chromate treated zinc-chromium electroplated steel sheet |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH01177386A JPH01177386A (en) | 1989-07-13 |
| JPH0765218B2 true JPH0765218B2 (en) | 1995-07-12 |
Family
ID=11494449
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63001187A Expired - Fee Related JPH0765218B2 (en) | 1987-03-31 | 1988-01-08 | Chromate treated zinc-chromium electroplated steel sheet |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0765218B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH042796A (en) * | 1990-04-19 | 1992-01-07 | Nippon Steel Corp | Hot dip galvanized steel sheet having zn-cr surface layer |
-
1988
- 1988-01-08 JP JP63001187A patent/JPH0765218B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH01177386A (en) | 1989-07-13 |
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