JPH0891842A - Production of basic chromium sulfate to be used for chromium system electroplating - Google Patents
Production of basic chromium sulfate to be used for chromium system electroplatingInfo
- Publication number
- JPH0891842A JPH0891842A JP22975594A JP22975594A JPH0891842A JP H0891842 A JPH0891842 A JP H0891842A JP 22975594 A JP22975594 A JP 22975594A JP 22975594 A JP22975594 A JP 22975594A JP H0891842 A JPH0891842 A JP H0891842A
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- Prior art keywords
- chromium
- reducing agent
- less
- amount
- sulfate
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Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、亜鉛−クロム系合金電
気めっき等のクロム系電気めっき製剤として使用する塩
基性硫酸クロムの製造方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing basic chromium sulfate used as a chromium-based electroplating preparation such as zinc-chromium alloy electroplating.
【０００２】[0002]
【従来の技術】近年、亜鉛−クロム系合金電気めっき等
のクロム系電気めっき鋼板は、耐蝕性が飛躍的に向上す
ることから、自動車、家電及び建材用途に使用されてき
ている。2. Description of the Related Art In recent years, chromium-based electroplated steel sheets such as zinc-chromium alloy electroplated sheets have been used for automobiles, home appliances and building materials because of their dramatically improved corrosion resistance.
【０００３】これらクロム系電気めっきは特開平１−５
５３９８号公報、特開平１−１９１７９８号公報、特開
平３−１２０５９３号公報（以上はＳＯ4 とＣｒのモル
比が１．５の硫酸クロム）、及び特開平６−１７３０９
号公報（ＳＯ4 とＣｒのモル比が１．０以上、１．５未
満の硫酸クロム）等が公知である。These chromium-based electroplatings are disclosed in JP-A-1-5.
5398, JP-A-1-191798, JP-A-3-120593 (the above is chromium sulfate having a molar ratio of SO 4 and Cr of 1.5), and JP-A-6-17309.
Japanese Laid-Open Patent Publication (chromium sulfate having a molar ratio of SO 4 to Cr of 1.0 or more and less than 1.5) is known.
【０００４】しかしながら、これらに使用されている硫
酸クロムは長期保管により、ゲル化、固化し、めっき製
造する際に連続補給ができないなど工業的に生産する場
合、安定してめっきできない欠点がある。However, the chromium sulphate used in these materials has a drawback that it cannot be stably plated in industrial production such as gelation and solidification due to long-term storage and continuous replenishment when plating is not possible.
【０００５】また、特開平６−１５８３９８号公報、特
開平６−１７３１００号公報及び特開平６−１７３０９
８号公報などには還元剤として無機系還元剤及び多価ア
ルコールを用いること及び還元後にＣｒ（VI）を残存さ
せる方法などが開示されているが、これらによって得ら
れる硫酸クロムも同様に、長期保管により、ゲル化、固
化し、めっき製造する際に連続補給ができないなどの欠
点が依然として解決されていない。Further, JP-A-6-158398, JP-A-6-173100 and JP-A-6-17309.
No. 8 and the like disclose the use of an inorganic reducing agent and a polyhydric alcohol as a reducing agent and a method of leaving Cr (VI) remaining after the reduction. The drawbacks such as gelation and solidification due to storage, and continuous replenishment during plating production have not been solved.
【０００６】また、硫酸クロムとしては、皮鞣し用に使
用されている固体の塩基性硫酸クロム（ＳＯ4 とＣｒの
モル比が０．８〜１．０）があるが、この場合、極端な
低硫酸比で還元するため、過剰の有機系還元剤が用いら
れることから、還元剤未反応物、中間分解物が多量に存
在し（皮鞣しの場合は、これらがマスキング剤として有
効に作用するため、その存在はむしろ歓迎されるもので
あった）、まためっき液中に三酸化二クロム（Ｃｒ2 Ｏ
3 ）の不溶解物を生じ、安定にめっきすることができな
いため使用されていない。As the chromium sulfate, there is solid basic chromium sulfate (molar ratio of SO 4 and Cr is 0.8 to 1.0) used for tanning, but in this case, Since it is reduced at a low sulfuric acid ratio, an excessive amount of organic reducing agent is used, so there is a large amount of unreacted reducing agent and intermediate decomposition products (in the case of skin tanning, these act effectively as masking agents. Therefore, its existence was rather welcomed), and dichromium trioxide (Cr 2 O) was added to the plating solution.
It is not used because it produces insoluble matter in 3 ) and cannot plate stably.
【０００７】[0007]
【発明が解決しようとする課題】本発明はかかる事情に
鑑みてなされたものであって、クロム系電気めっきを製
造する際に、容易にＣｒ源を補給することができ、か
つ、めっき安定性に優れたクロム系電気めっき用塩基性
硫酸クロムの製造方法を提供することを目的とする。SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is possible to easily replenish the Cr source when producing chromium-based electroplating and to stabilize the plating stability. An object of the present invention is to provide a method for producing a chromium-based basic chromium sulfate excellent in electroplating.
【０００８】[0008]
【課題を解決するための手段】本発明者らは、上記課題
を解決するために詳細に検討を行った結果、硫酸クロム
のゲル化、固化、およびめっきの安定性は、水和錯状態
の変化に起因し、ＳＯ4 とＣｒのモル比および硫酸クロ
ム製造時に生成される還元剤の未反応物、中間分解物の
残存が影響していることを見出した。そこで、この問題
を解決する手段を鋭意検討した結果、ＳＯ4 とＣｒのモ
ル比を化学量論比１．４以下にした硫酸存在下で、還元
剤の種類、添加順序、速度、熟成条件を制御し、未反応
還元剤、還元剤中間分解物の残存をなくすることによ
り、めっきの補給性、めっき安定性に優れたクロム系電
気めっき用塩基性硫酸クロムを製造することが可能であ
ることを見出した。Means for Solving the Problems As a result of detailed investigations for solving the above problems, the present inventors have found that the gelation, solidification, and stability of plating of chromium sulfate are in the hydration complex state. It was found that due to the change, the molar ratio of SO 4 and Cr and the remaining unreacted product of the reducing agent and intermediate decomposition products produced during the production of chromium sulfate had an influence. Then, as a result of earnestly studying the means for solving this problem, as a result, in the presence of sulfuric acid in which the molar ratio of SO 4 and Cr is 1.4 or less, the type of reducing agent, the order of addition, the rate, and the aging conditions are By controlling and eliminating the remaining unreacted reducing agent and intermediate decomposition products of reducing agent, it is possible to produce a basic chromium sulfate for chromium electroplating that is excellent in plating replenishment and plating stability. Found.
【０００９】本発明はこれらの知見に基づいてなされた
もので、第１に、三酸化クロム水溶液を硫酸の存在下で
還元剤により還元してクロム系電気めっきに使用する塩
基性硫酸クロムを製造する方法において、含有するＳＯ
4 とＣｒのモル比を１．１以上、１．４以下とし、前記
還元剤としてアルコール類を用い、その添加量を還元後
の液中のＣｒ（VI）濃度が全Ｃｒ量の５％以下になるよ
うに、理論添加量の８０％以上、１００％以下とするこ
とを特徴とするクロム系電気めっきに使用する塩基性硫
酸クロムの製造方法を提供する。The present invention has been made on the basis of these findings. Firstly, an aqueous solution of chromium trioxide is reduced with a reducing agent in the presence of sulfuric acid to produce basic chromium sulfate for use in chromium-based electroplating. In the method of
The molar ratio of 4 and Cr is 1.1 or more and 1.4 or less, alcohols are used as the reducing agent, and the added amount of Cr (VI) concentration in the liquid after reduction is 5% or less of the total Cr amount. Therefore, a method for producing basic chromium sulfate for use in chromium-based electroplating, characterized in that the amount is 80% or more and 100% or less of the theoretical addition amount.
【００１０】第２に、三酸化クロム水溶液を硫酸の存在
下で還元剤により還元してクロム系電気めっきに使用す
る塩基性硫酸クロムを製造する方法において、含有する
ＳＯ4 とＣｒのモル比を１．１以上、１．４以下とし、
前記還元剤として過酸化水素を用い、その濃度を２〜３
５％として、その添加量を還元後の液中のＣｒ（VI）濃
度が全Ｃｒ量の５％以下になるように、理論添加量の１
００％以上、２５０％以下とすることを特徴とするクロ
ム系電気めっきに使用する塩基性硫酸クロムの製造方法
を提供する。Secondly, in a method for producing a basic chromium sulfate for use in chromium-based electroplating by reducing an aqueous solution of chromium trioxide with a reducing agent in the presence of sulfuric acid, the molar ratio of SO 4 and Cr to be contained is changed. 1.1 or more and 1.4 or less,
Hydrogen peroxide is used as the reducing agent, and its concentration is set to 2-3.
5%, and the addition amount is set to 1% of the theoretical addition amount so that the Cr (VI) concentration in the liquid after reduction is 5% or less of the total Cr amount.
There is provided a method for producing basic chromium sulfate for use in chromium-based electroplating, which is characterized in that it is set to 00% or more and 250% or less.
【００１１】第３に、三酸化クロム水溶液を硫酸の存在
下で還元剤により還元してクロム系電気めっきに使用す
る塩基性硫酸クロムを製造する方法において、含有する
ＳＯ4 とＣｒのモル比を１．１以上、１．４以下とし、
前記還元剤として糖類およびアルコール類を含む有機系
還元剤を用いて、三酸化クロムに対する理論添加量の８
０％以下の範囲で還元した後に、過酸化水素を還元後の
液中のＣｒ（VI）の濃度が全Ｃｒ量の５％以下になるよ
うな添加量で添加することを特徴とするクロム系電気め
っきに使用する塩基性硫酸クロムの製造方法を提供す
る。Thirdly, in a method for producing a basic chromium sulfate for use in chromium-based electroplating by reducing an aqueous solution of chromium trioxide with a reducing agent in the presence of sulfuric acid, the molar ratio of SO 4 and Cr contained is changed. 1.1 or more and 1.4 or less,
An organic reducing agent containing saccharides and alcohols was used as the reducing agent, and the theoretical addition amount of 8% to chromium trioxide was used.
After reduction in the range of 0% or less, hydrogen peroxide is added in an amount such that the concentration of Cr (VI) in the reduced liquid is 5% or less of the total Cr amount. Provided is a method for producing basic chromium sulfate used for electroplating.
【００１２】第４に、上記第１〜第３の方法において、
還元剤添加後の反応液を１００℃以上で１時間以上保持
することを特徴とするクロム系電気めっきに使用する塩
基性硫酸クロムの製造方法を提供する。Fourthly, in the above first to third methods,
A method for producing basic chromium sulfate for use in chromium-based electroplating, characterized in that the reaction solution after addition of the reducing agent is kept at 100 ° C or higher for 1 hour or longer.
【００１３】第５に、三酸化クロム水溶液を硫酸の存在
下で還元剤により還元してクロム系電気めっきに使用す
る塩基性硫酸クロムを製造する方法において、含有する
ＳＯ4 とＣｒのモル比を１．１以上、１．４以下とし、
前記還元剤として糖類を用い、その添加量を還元後の液
中のＣｒ（VI）の濃度が全Ｃｒ量の５％以下になるよう
に、理論添加量の８０％以上、１００％以下とし、還元
剤添加後の反応液を１００℃以上で１時間以上保持する
ことを特徴とするクロム系電気めっきに使用する塩基性
硫酸クロムの製造方法を提供する。Fifth, in the method for producing basic chromium sulfate used for chromium-based electroplating by reducing an aqueous solution of chromium trioxide with a reducing agent in the presence of sulfuric acid, the molar ratio of SO 4 and Cr contained is 1.1 or more and 1.4 or less,
Sugar is used as the reducing agent, and the addition amount thereof is 80% or more and 100% or less of the theoretical addition amount so that the concentration of Cr (VI) in the liquid after the reduction is 5% or less of the total Cr amount, A method for producing basic chromium sulfate for use in chromium-based electroplating, characterized in that the reaction solution after addition of the reducing agent is kept at 100 ° C or higher for 1 hour or longer.
【００１４】[0014]
【作用】以下、本発明について詳細に説明する。The present invention will be described in detail below.
【００１５】本発明における硫酸クロムは、Ｃｒ(III)
を主体とした、濃度１０％以上５０％以下の塩基性硫酸
クロム水溶液である。濃度が１０％未満では運搬、貯蔵
に費用がかかり、５０％超では保持時に沈殿を生じ、め
っき液への補給には、溶解に時間がかかり、一定濃度の
管理が困難となり得策ではない。Chromium sulfate in the present invention is Cr (III)
Is a basic chromium sulfate aqueous solution having a concentration of 10% or more and 50% or less. If the concentration is less than 10%, it will be expensive to transport and store, and if it exceeds 50%, precipitation will occur during holding, and it will take a long time to dissolve the plating solution, and it will be difficult to control a certain concentration, which is not a good idea.
【００１６】さらに水分を除去した固体の硫酸クロム
は、ＳＯ4 とＣｒのモル比が１．５未満では、一部三酸
化二クロム（Ｃｒ2 Ｏ3 ）となり、めっき液に溶解せ
ず、めっきに使用する硫酸クロムとしては不適である。Further, solid chromium sulfate from which water has been removed has a partial dichromium trioxide (Cr 2 O 3 ) content when the molar ratio of SO 4 and Cr is less than 1.5, and it does not dissolve in the plating solution. It is not suitable as chromium sulphate used for.
【００１７】なお、クロム系電気めっきはＣｒイオンと
してはＣｒ(III) を主体とするものであるので、Ｃｒ源
供給用製剤としてはＣｒ(III) を主体としたものでなけ
ればならない。Since chromium-based electroplating is mainly composed of Cr (III) as Cr ions, the Cr source supply preparation must be mainly composed of Cr (III).
【００１８】一般に硫酸クロムはＣｒ2 （ＳＯ4 ）3 と
いう化学式で表現される。この場合のクロムは３価のイ
オンであるが、３価のクロムは一般にヘキサコクロム
（ヘキサアクオクロム）と言われ、正八面体の中心に位
置するＣｒ原子に対し、６個の水分子を配位した形を持
った錯イオンを形成しており、これを模式的に示すと、
［Ｃｒ（Ｈ2 Ｏ）6 ］3+となる。これが硫酸根とイオン
結合したものがＣｒ2 （ＳＯ4 ）3 すなわち硫酸クロム
である。Chromium sulfate is generally represented by the chemical formula Cr 2 (SO 4 ) 3 . Chromium in this case is a trivalent ion, but the trivalent chromium is generally called hexacochrome (hexaaquochrome), and six water molecules are coordinated to the Cr atom located at the center of the octahedron. Forming complex ions with a shape, and schematically showing this,
It becomes [Cr (H 2 O) 6 ] 3+ . Cr 2 (SO 4 ) 3, that is, chromium sulfate, is ionically bonded to sulfate.
【００１９】ここで、ヘキサコクロム中の水分子は様々
な条件下でＨ2 Ｏ→Ｈ+ ＋ＯＨ- のように解離し、プロ
トン（Ｈ+ ）を放出する。この時の状態は以下に示す
（１）式で表わすことができる。Here, the water molecules in hexacochrome dissociate as H 2 O → H + + OH − under various conditions to release protons (H + ). The state at this time can be expressed by the following equation (1).
【００２０】 ［Ｃｒ（Ｈ2 Ｏ）6 ］3+ → ［Ｃｒ（Ｈ2 Ｏ）5 ・ＯＨ］2+＋Ｈ+ ……（１） （１）式に示すような錯イオンが硫酸根とイオン結合す
るとＣｒ（ＯＨ）ＳＯ4 という化学式で示される塩基性
硫酸クロムとなる。[Cr (H 2 O) 6 ] 3+ → [Cr (H 2 O) 5 OH] 2+ + H + (1) Complex ions such as those represented by the formula (1) are sulfate ions and ions. When combined, they become basic chromium sulfate represented by the chemical formula Cr (OH) SO 4 .
【００２１】この塩基性硫酸クロムの示性式は一般に、
Ｃｒ（ＯＨ）3-2X（ＳＯ4 ）X のように表される。ここ
で、ＸはＣｒに対するＳＯ4 のモル比を示し、塩基性硫
酸クロムはこのＸの値が０を超え１．５未満の範囲をと
る。ちなみにＸ＝０の場合はＣｒ（ＯＨ）3 、すなわち
水酸化クロムであり、Ｘ＝１．５の場合はＣｒ2 （ＳＯ
4 ）3 、すなわち硫酸クロムである。The general formula of this basic chromium sulfate is generally:
It is expressed as Cr (OH) 3-2X (SO 4 ) X. Here, X represents a molar ratio of SO 4 to Cr, and the basic chromium sulfate has a value of X exceeding 0 and less than 1.5. By the way, when X = 0, it means Cr (OH) 3 , that is, chromium hydroxide, and when X = 1.5, Cr 2 (SO).
4 ) 3 , ie chromium sulphate.
【００２２】まず、本発明における硫酸の三酸化クロム
に対する添加量であるが、ＳＯ4 とＣｒのモル比で表し
て１．１以上１．４以下でなければならない。好ましく
は１．１〜１．３の範囲である。ＳＯ4 とＣｒのモル比
が１．４を超えると製造後３ケ月以内でゲル化が起こ
り、補給配管を閉塞してクロム系電気めっき液への補給
が困難となり、さらにはめっき再現性がなくなる。これ
は、ゲル化した塩基性硫酸クロムではめっき液でのＣｒ
(III) の錯状態が異なるためと推定される。First, the addition amount of sulfuric acid to chromium trioxide in the present invention must be 1.1 to 1.4 in terms of the molar ratio of SO 4 and Cr. The range is preferably 1.1 to 1.3. When the molar ratio of SO 4 and Cr exceeds 1.4, gelation occurs within 3 months after production, the supply pipe is blocked and it becomes difficult to supply to the chromium-based electroplating solution, and further the plating reproducibility is lost. . This is due to the fact that in the case of gelled basic chromium sulfate, Cr in the plating solution
It is presumed that the complex state of (III) is different.
【００２３】また、ＳＯ4 とＣｒのモル比が１．１未満
でも製造後３ケ月以内でゲル化が起こり、同時にめっき
液への補給が困難となり、めっき再現性がなくなる。Further, even if the molar ratio of SO 4 to Cr is less than 1.1, gelation occurs within 3 months after production, and at the same time, replenishment to the plating solution becomes difficult and plating reproducibility is lost.
【００２４】ＳＯ4 とＣｒのモル比が１．１以上１．４
以下では、３ケ月以上ゲル化が起こらず、工業的に塩基
性硫酸クロムを補給する上での支障は無くなる。さら
に、１．１以上１．３以下では１２ケ月以上を経てもゲ
ル化は全く起こらない。Molar ratio of SO 4 and Cr is 1.1 or more 1.4
In the following, gelation does not occur for 3 months or more, and there is no obstacle to industrially supplying basic chromium sulfate. Further, if it is 1.1 or more and 1.3 or less, gelation does not occur even after 12 months or more.
【００２５】ＳＯ4 とＣｒのモル比が１．１以上１．４
以下でゲル化を生じない原因については明らかではない
が、１．４を超えるとＳＯ4 とＣｒ(III) が水溶液中で
規則正しく配位して巨大分子を形成し、１．１未満では
Ｃｒ(III) 水和錯体が連続巨大化するのに対し、１．１
以上１．４以下ではこのようなことが生じないためと推
定される。Molar ratio of SO 4 and Cr is 1.1 or more 1.4
The reason why gelation does not occur is not clear below, but when it exceeds 1.4, SO 4 and Cr (III) coordinate regularly in an aqueous solution to form a macromolecule, and when it is less than 1.1, Cr (III) is formed. III) While the hydrated complex grows continuously, 1.1
It is presumed that such a situation does not occur at 1.4 or more and 1.4 or less.
【００２６】このように、ＳＯ4 とＣｒのモル比を１．
１以上１．４以下とするには、ＳＯ4 とＣｒのモル比が
１．４以上の塩基性硫酸クロムに炭酸バリウムなど硫酸
と難溶性塩を形成するものを添加する方法もあるが、塩
基性硫酸クロム作成後に硫酸比調整工程を付加する必要
があるうえ、コスト高となる。As described above, the molar ratio of SO 4 and Cr is 1.
There is also a method for adding 1 or more and 1.4 or less to basic chromium sulfate having a molar ratio of SO 4 and Cr of 1.4 or more to barium carbonate or the like that forms a sparingly soluble salt with sulfuric acid, It is necessary to add a sulfuric acid ratio adjusting step after the formation of the acidic chromium sulfate, and the cost becomes high.
【００２７】従って、本発明では三酸化クロム還元時に
予めＳＯ4 とＣｒのモル比を１．１以上１．４以下と
し、還元剤と反応せしめて塩基性硫酸クロムを作成する
ものである。Therefore, in the present invention, the basic chromium sulfate is prepared by reducing the molar ratio of SO 4 and Cr to 1.1 or more and 1.4 or less in advance during reduction of chromium trioxide and reacting with a reducing agent.
【００２８】また、先に述べたように、クロム系電気め
っきはＣｒ(III) を主体としたものでなければならない
から、使用に供する塩基性硫酸クロム中のＣｒ(VI)の濃
度は、全Ｃｒ量の５％以下でなければならない。Ｃｒ(V
I)の濃度が５％を超えると、電気めっきの際に、Ｃｒ(V
I)の還元に電気が費やされ、めっき効率の極端な低下を
もたらす。Further, as described above, since the chromium-based electroplating must be mainly composed of Cr (III), the concentration of Cr (VI) in the basic chromium sulfate to be used should be It must be 5% or less of the amount of Cr. Cr (V
If the concentration of I) exceeds 5%, Cr (V
Electricity is consumed for the reduction of I), resulting in an extremely low plating efficiency.
【００２９】なお、塩基性硫酸クロム中のＣｒ(VI)の濃
度が０．１ｐｐｍ以上であれば、後に述べる還元剤の残
分および分解物の残存する恐れがなくなるものと考えら
れ、クロム系電気めっき密着性が一層向上する可能性が
ある。If the concentration of Cr (VI) in the basic chromium sulfate is 0.1 ppm or more, it is considered that there is no risk of the residual reducing agent and decomposed product remaining, which will be described later. The plating adhesion may be further improved.
【００３０】還元剤については、上述したＳＯ4 とＣｒ
のモル比の範囲において、以下に述べる有機系還元剤お
よび／または無機還元剤を用いることで、ゲル化せず、
補給安定性の良い塩基性硫酸クロムを確保することがで
きる。Regarding the reducing agent, SO 4 and Cr described above are used.
In the range of the molar ratio of, by using the organic reducing agent and / or inorganic reducing agent described below, without gelation,
It is possible to secure basic chromium sulfate with good replenishment stability.
【００３１】三酸化クロムの還元反応は、下式に示す如
く酸（Ｈ+ ）の消費を伴うものである。The reduction reaction of chromium trioxide involves the consumption of acid (H + ) as shown in the following formula.
【００３２】 ＣｒＯ4 2-＋８Ｈ+ ＋３ｅ- → Ｃｒ3+＋４Ｈ2 Ｏ しかしながら、上述の如くＳＯ4 とＣｒのモル比を１．
５より減じて１．１以上１．４以下とする場合、三酸化
クロムを十分還元するには、還元剤を過剰に使用しなく
てはならなくなる。CrO 4 2− + 8H + + 3e − → Cr 3+ + 4H 2 O However, as described above, the molar ratio of SO 4 and Cr is 1.
When it is reduced from 5 to 1.1 or more and 1.4 or less, it is necessary to excessively use the reducing agent in order to sufficiently reduce chromium trioxide.
【００３３】このため、従来使用されているグルコー
ス、澱粉、リグニン、廃糖蜜等の糖類系の有機還元剤で
は、その添加率を高くした場合に還元分解物がＣｒ(II
I) と強固な錯配位性のカルボン酸類を形成するか、ま
たはタール系物質なり、これらが多くなると、原因は明
らかではないが、ゲル化しやすくなる傾向を示す。ま
た、これらの還元分解物は、亜鉛−クロム合金電気めっ
きなどのめっき時には、鋼板に付着してめっき密着性を
損なう場合もある。Therefore, in the conventionally used saccharide-based organic reducing agents such as glucose, starch, lignin, and molasses, the reduction decomposition product is Cr (II) when the addition rate is increased.
It forms a strong complex-coordinating carboxylic acid with I) or becomes a tar-based substance. When the amount of these substances increases, the cause is not clear, but gelation tends to occur easily. In addition, these reduced decomposition products may adhere to the steel plate during plating such as zinc-chromium alloy electroplating and impair the plating adhesion.
【００３４】本発明は、低硫酸比（ＳＯ4 とＣｒのモル
比）の難還元性状態で、めっきに障害とならぬよう還元
剤残分および還元剤分解物の低減を図ったものである。The present invention is intended to reduce the reducing agent residue and the reducing agent decomposed products so as not to hinder plating in a difficult reducing state with a low sulfuric acid ratio (molar ratio of SO 4 and Cr). .
【００３５】以上の観点から、めっき密着性の一層の向
上を図るにあたって、還元剤として有機還元剤を用いる
場合には、還元後の中間生成物を残存させないようにす
るため、分解しやすいアルコール類を用いることが好ま
しい。ここでいうアルコール類とは一価、二価、三価ア
ルコール及びその他の多価アルコールを含むものであ
り、例えばメタノール、ポリエチレングリコール、グリ
セリン等を挙げることができる。また、有機系還元剤の
添加量は、還元反応後に中間生成物を残存させないよう
にする観点から、理論量の８０〜１００％とすることが
好ましい。従来用いられていた澱粉やグルコースは分解
しにくく、還元反応後に中間生成物を残存させない観点
からは、上記範囲内で添加率を低めに設定する必要があ
るが、上記アルコール類は分解しやすいため、その添加
率を高くすることが可能である。From the above viewpoints, when an organic reducing agent is used as the reducing agent in order to further improve the plating adhesion, alcohols that are easily decomposed are used so as not to leave the intermediate product after the reduction. Is preferably used. The alcohols referred to here include monohydric, dihydric, trihydric alcohols and other polyhydric alcohols, and examples thereof include methanol, polyethylene glycol and glycerin. Further, the addition amount of the organic reducing agent is preferably 80 to 100% of the theoretical amount from the viewpoint of preventing the intermediate product from remaining after the reduction reaction. Conventionally used starch and glucose are difficult to decompose, and from the viewpoint of not leaving an intermediate product after the reduction reaction, it is necessary to set a low addition rate within the above range, but the above alcohols are easily decomposed. It is possible to increase the addition rate.
【００３６】還元反応後の液中のＣｒ(VI)を、前述した
範囲の含有量で残存させることで、液中の還元剤はほぼ
完全に分解され、中間生成物（還元剤分解物）の残量を
極微量に抑制することが可能となる。つまり、還元反応
後の液中のＣｒ(VI)の濃度が全Ｃｒ量の５％以下になる
ように有機系還元剤の添加量を８０％以上１００％以下
にすることにより、還元反応後の中間生成物の残存量を
極めて少なくすることができる。By allowing Cr (VI) in the liquid after the reduction reaction to remain in a content within the above-mentioned range, the reducing agent in the liquid is almost completely decomposed, and an intermediate product (reducing agent decomposition product) is obtained. It is possible to suppress the remaining amount to an extremely small amount. In other words, by adjusting the addition amount of the organic reducing agent to 80% or more and 100% or less so that the concentration of Cr (VI) in the liquid after the reduction reaction is 5% or less of the total Cr amount, The residual amount of the intermediate product can be extremely reduced.
【００３７】さらに、澱粉、蔗糖、グルコース等の糖類
またはアルコール類の有機系還元剤を用いて三酸化クロ
ムの理論還元量の８０％以下の範囲で還元し、しかる後
に、過酸化水素のような無機系還元剤を還元後の液中の
Ｃｒ（VI）の濃度が全Ｃｒ量の５％以下になるように添
加してもよい。Further, an organic reducing agent of saccharides such as starch, sucrose, glucose or the like or alcohols is used to reduce the amount of chromium trioxide in the range of 80% or less of the theoretical reduction amount. The inorganic reducing agent may be added so that the concentration of Cr (VI) in the liquid after the reduction is 5% or less of the total Cr amount.
【００３８】無機還元剤としては過酸化水素が好まし
い。これを用いる場合には、反応後の生成物は塩基性硫
酸クロムの他は、水と酸素のみであり、全て系外へ逃散
するため中間生成物は残らない。しかし、有機系還元剤
に比べその反応は激しく、自己分解反応を伴うため、そ
の添加率は原液を用いた場合、理論量の２５０〜５００
％にも達する。このような自己分解反応を抑制するため
には還元剤を希釈することが好ましく、その添加率を理
論量の１５０〜２５０％の適当な値にするためには、そ
の濃度を５〜３５％にすることが好ましい。さらに好ま
しくは５〜１５％である。無機還元剤を用いた場合にも
液中のＣｒ(VI)濃度が全Ｃｒの５％以下になるように、
その添加率を理論量の１５０〜２５０％の適宜の値に設
定すればよい。Hydrogen peroxide is preferred as the inorganic reducing agent. When this is used, the products after the reaction are only water and oxygen in addition to the basic chromium sulfate and all escape to the outside of the system, so that no intermediate product remains. However, the reaction is more vigorous than the organic reducing agent and is accompanied by an autolysis reaction, so that the addition rate is 250 to 500 which is the theoretical amount when the stock solution is used.
Reaches as high as%. In order to suppress such self-decomposition reaction, it is preferable to dilute the reducing agent, and in order to make its addition rate an appropriate value of 150 to 250% of the theoretical amount, its concentration should be 5 to 35%. Preferably. More preferably, it is 5 to 15%. Even if an inorganic reducing agent is used, the Cr (VI) concentration in the liquid should be 5% or less of the total Cr,
The addition rate may be set to an appropriate value of 150 to 250% of the theoretical amount.
【００３９】以上のようにして条件を適切に調整して還
元液を製造した場合には、その中に余分な中間生成物や
ガス体等がほとんど存在しないようにすることは可能で
あるが、これらを確実に除去するためには熟成処理を行
うことが好ましい。従来の塩基性硫酸クロムを製造する
場合にも熟成処理を行っていたが、その目的は生成する
中間生成物の量比の一定化にあったため、その条件は４
０〜６０℃で１日〜１週間程度保持という緩やかなもの
であった。これに対して、本発明ではその目的は還元液
中から各種中間体やガス体を完全に除去するところにあ
るため、その条件は従来の条件に比較して過酷なものと
なる。特に、中間生成物が多量に残存しやすい有機物系
の澱粉、蔗糖、グルコース等の糖類を還元剤に用いた場
合には、その還元剤添加量を上述したアルコール類と同
様８０％以上１００％以下としたうえで、さらに１００
℃以上沸騰温度以下で１時間以上、特に好ましくは４８
時間以上保持して中間生成物を極力分解することが、ゲ
ル化安定性さらにはめっき密着性を確保するうえで必要
である。When the reducing solution is produced by appropriately adjusting the conditions as described above, it is possible to make almost no extra intermediate products, gas bodies and the like therein. In order to surely remove these, it is preferable to perform an aging treatment. Aging treatment was also performed in the conventional production of basic chromium sulfate, but the purpose was to keep the ratio of the amount of intermediate products formed constant.
It was a gentle one that it was kept at 0 to 60 ° C. for about 1 day to 1 week. On the other hand, in the present invention, the purpose is to completely remove various intermediates and gaseous bodies from the reducing liquid, so that the conditions are more severe than the conventional conditions. In particular, when an organic-based starch, sucrose, glucose, or other saccharide, in which a large amount of an intermediate product is likely to remain, is used as a reducing agent, the reducing agent addition amount is 80% or more and 100% or less as in the case of the alcohols described above. And then 100 more
℃ or more and boiling temperature or less for 1 hour or more, particularly preferably 48
It is necessary to maintain the time or longer to decompose the intermediate product as much as possible in order to secure gelling stability and plating adhesion.
【００４０】なお、この１００℃以上の沸騰温度以下で
１時間以上の熟成処理は、還元剤としてアルコール類、
過酸化水素を用いる場合、および有機系還元剤を用い最
終的に過酸化水素を用いる場合にも、電気めっきのめっ
き密着性を一層向上させるので好ましい。The aging treatment for 1 hour or more at a boiling temperature of 100 ° C. or higher is performed by using alcohols as a reducing agent,
It is preferable to use hydrogen peroxide and also to finally use hydrogen peroxide with an organic reducing agent, because the plating adhesion of electroplating is further improved.
【００４１】[0041]
【実施例】次に、本発明の実施例を比較例とともに挙げ
る。EXAMPLES Next, examples of the present invention will be given together with comparative examples.
【００４２】Ｃｒ(VI)として１８０ｇ／ｌになるように
三酸化クロムを脱イオン水に溶解し、それに対しＳＯ4
／Ｃｒモル比が表１に示す値になるように硫酸を添加し
た。この混合溶液に対し、表１に示すような還元剤を所
定量添加し、残存するＣｒ(VI)濃度が全Ｃｒ量の５％以
下になるように還元および熟成を行った。得られた塩基
性硫酸クロムを用い、ゲル化状態を調査するとともに、
めっき液を建浴し、電気めっき鋼板を製造した。Chromium trioxide was dissolved in deionized water so that Cr (VI) was 180 g / l, and SO 4 was added thereto.
Sulfuric acid was added so that the / Cr molar ratio became the value shown in Table 1. A predetermined amount of a reducing agent as shown in Table 1 was added to this mixed solution, and reduction and aging were performed so that the remaining Cr (VI) concentration was 5% or less of the total Cr amount. Using the obtained basic chromium sulfate, while investigating the gelation state,
An electroplated steel sheet was manufactured by bathing the plating solution.
【００４３】また、比較例として、無機系還元剤を用い
てＳＯ4 ／Ｃｒモル比が１．０および１．５になるよう
に調整したもの、ならびに有機系還元剤を用いて緩やか
な熟成条件で調整した塩基性硫酸クロム、さらには残留
Ｃｒ(VI)濃度が全Ｃｒ量の５％を超えるものをそれぞれ
作成した。As comparative examples, inorganic reducing agents were used to adjust the SO 4 / Cr molar ratios to 1.0 and 1.5, and organic reducing agents were used for mild aging conditions. Basic sulphate prepared in (4) and further having a residual Cr (VI) concentration of more than 5% of the total Cr content were prepared.
【００４４】なお、めっき条件はめっき浴中のＣｒ3+：
５５ｇ／ｌ、Ｚｎ2+：６５ｇ／ｌ、Ｎａ：１２ｇ／ｌ、
ポリエチレングリコール１５００：１．５ｇ／ｌでｐＨ
１．５、浴温度５０℃のめっき浴を用いて、板厚が０．
８ｍｍの鋼板を電流密度１６０Ａ／ｄｍ2 、流速６０ｍ
／ｍｉｎ、めっき量２０ｇ／ｍ2 とした。The plating conditions are Cr 3+ in the plating bath:
55 g / l, Zn 2+ : 65 g / l, Na: 12 g / l,
Polyethylene glycol 1500: pH at 1.5 g / l
Using a plating bath having a bath temperature of 50 ° C. and a plate thickness of 0.1.
8mm steel plate with current density 160A / dm 2 , flow velocity 60m
/ Min, and the plating amount was 20 g / m 2 .
【００４５】表１に、このように作成した塩基性硫酸ク
ロムの製造条件、ならびに作成した塩基性硫酸クロムの
品質およびめっき鋼板の品質を示す。Table 1 shows the production conditions of the basic chromium sulfate thus prepared, and the quality of the basic chromium sulfate thus prepared and the quality of the plated steel sheet.
【００４６】表１から明らかなように、本発明の実施例
は全て３カ月以上ゲル化することなく、かつ、めっき液
に補給を行っても安定しためっき組成が得られた。さら
に、ＳＯ4 ／Ｃｒモル比が１．１〜１．３でかつ還元剤
にアルコール類、過酸化水素を用いたものは１年以上ゲ
ル化せずに安定していた。As is clear from Table 1, in all the examples of the present invention, a stable plating composition was obtained without gelation for 3 months or more, and even when the plating solution was replenished. Further, those having an SO 4 / Cr molar ratio of 1.1 to 1.3 and using alcohols or hydrogen peroxide as a reducing agent were stable without gelation for one year or longer.
【００４７】さらに、還元剤にアルコール類、過酸化水
素を用い、熟成処理を１００℃以上で１時間以上行った
ものは、めっき鋼板のめっき密着性が一層優れたものに
なった。Further, when alcohols and hydrogen peroxide were used as the reducing agents and the aging treatment was carried out at 100 ° C. or higher for 1 hour or longer, the plating adhesion of the plated steel sheet was further improved.
【００４８】以上の実施例により、本発明の優れた効果
を実証することができた。The excellent effects of the present invention can be demonstrated by the above examples.
【００４９】[0049]
【表１】 注１） ゲル化時間は、冷蔵庫（０〜５℃）で保管し、
３カ月経過前にゲル化したものを×（実用不可）、３カ
月以上１年未満のものを○（実用上問題なし）、１年以
上のものを◎（全く問題なし）とした。[Table 1] Note 1) Gelation time is stored in a refrigerator (0-5 ° C),
Those gelled before 3 months were rated x (not practical), those 3 months or more but less than 1 year were rated ◯ (no practical problems), and those 1 year or more were rated ◎ (no problems at all).
【００５０】注２） めっき密着性は、Ｃｒ組成が５％
以上のものについて、白色ビニールテープを貼り付け、
テープ部を内側中心にして、該めっき鋼板を密着折り曲
げした後、開いてテープを剥し、テープ裏面への剥離め
っき層の有無で評価した。全く剥離痕跡のないものを
◎、薄くスジのつくもの（実用上問題なし）を○、めっ
き剥離のあるもの（実用不可）を×とした。Note 2) The plating adhesion is such that the Cr composition is 5%.
About the above, attach white vinyl tape,
The coated steel sheet was bent in close contact with the tape portion as the inner center, then opened and the tape was peeled off, and the presence or absence of a peeling plating layer on the back surface of the tape was evaluated. Those with no trace of peeling were marked with ⊚, those with thin streaks (no problems in practice) were marked with ◯, and those with peeling of plating (not practical) were marked with x.
【００５１】注３） 補給後のめっき安定性は、上記め
っき浴を１０％水で希釈した後に、３カ月経過した塩基
性硫酸クロムおよび硫酸、炭酸亜鉛、硫酸ナトリウム、
ポリエチレングリコールを添加して初期めっき浴濃度に
戻し、同一条件でめっきを行い、めっきクロム組成の変
化を化学分析で評価した。Ｃｒ組成の差が初期に比較し
て５％以下のものを○（良好）、５％以上のものを×
（実用不可）とした。Note 3) The stability of plating after replenishment is as follows: basic chromium sulfate and sulfuric acid, zinc carbonate, sodium sulfate, 3 months after the plating bath was diluted with 10% water.
Polyethylene glycol was added to restore the initial plating bath concentration, plating was performed under the same conditions, and changes in the plated chromium composition were evaluated by chemical analysis. If the difference in Cr composition is 5% or less compared to the initial stage, it is ○ (good), and if it is 5% or more, it is ×.
(Not practical)
【００５２】[0052]
【発明の効果】以上説明したように、本発明によって製
造された塩基性硫酸クロムは液状で極めて安定してお
り、クロム系電気めっきを行なう際に、クロム錯塩の組
成が安定しているので従来の硫酸クロムに比べめっき液
の変化が少なく、安定した状態でめっき作業を行なうこ
とができる。また、硫酸クロムに比べ組成中の酸根量が
少ないので、めっき液中に蓄積する酸根量が少なく抑え
られ、さらに酸根の除去に際しても沈殿を生成するため
の薬剤量及び沈殿の発生量を従来よりも抑制することが
可能となる。しかも、長期保存下でゲル化を起こさない
ため、取扱いが容易である。さらに、めっき密着性の一
層の向上も可能とする。以上のように、本発明は工業上
大なる有益性をもたらすものである。As described above, the basic chromium sulfate produced according to the present invention is liquid and extremely stable, and the composition of the chromium complex salt is stable when performing chromium-based electroplating. Compared with the chromium sulphate, the plating solution does not change much and the plating operation can be performed in a stable state. In addition, since the amount of acid radicals in the composition is smaller than that of chromium sulfate, the amount of acid radicals that accumulate in the plating solution can be suppressed to a smaller amount, and the amount of chemicals and the amount of precipitates that generate precipitates when removing acid radicals can be reduced compared to conventional methods. Can also be suppressed. Moreover, it does not cause gelation under long-term storage, and is easy to handle. Further, it is possible to further improve the plating adhesion. As described above, the present invention brings great industrial advantages.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 鈴木 眞一 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 金丸 辰也 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 Shinichi Suzuki 5-3 Tokai-cho, Tokai-shi, Aichi Pref.Nippon Steel Corporation (72) Inventor Tatsuya Kanemaru 5-3 Tokai-cho, Tokai-shi, Aichi Nippon Steel Co., Ltd. Nagoya Steel Works
Claims (5)
元剤により還元してクロム系電気めっきに使用する塩基
性硫酸クロムを製造する方法において、含有するＳＯ4
とＣｒのモル比を１．１以上、１．４以下とし、前記還
元剤としてアルコール類を用い、その添加量を還元後の
液中のＣｒ（VI）濃度が全Ｃｒ量の５％以下になるよう
に、理論添加量の８０％以上、１００％以下とすること
を特徴とするクロム系電気めっきに使用する塩基性硫酸
クロムの製造方法。1. A method for producing a basic chromium sulfate used for chromium-based electroplating by reducing an aqueous solution of chromium trioxide with a reducing agent in the presence of sulfuric acid, containing SO 4
The molar ratio of Cr to Cr is 1.1 or more and 1.4 or less, alcohols are used as the reducing agent, and the addition amount of Cr (VI) concentration in the liquid after reduction is 5% or less of the total Cr amount. As described above, the method for producing basic chromium sulfate used in chromium-based electroplating, characterized in that the amount is 80% or more and 100% or less of the theoretical addition amount.
元剤により還元してクロム系電気めっきに使用する塩基
性硫酸クロムを製造する方法において、含有するＳＯ4
とＣｒのモル比を１．１以上、１．４以下とし、前記還
元剤として過酸化水素を用い、その濃度を２〜３５％と
して、その添加量を還元後の液中のＣｒ（VI）濃度が全
Ｃｒ量の５％以下になるように、理論添加量の１００％
以上、２５０％以下とすることを特徴とするクロム系電
気めっきに使用する塩基性硫酸クロムの製造方法。2. A method for producing basic chromium sulfate used for chromium-based electroplating by reducing an aqueous solution of chromium trioxide with a reducing agent in the presence of sulfuric acid, containing SO 4
The molar ratio of Cr and Cr is 1.1 or more and 1.4 or less, hydrogen peroxide is used as the reducing agent, the concentration is 2 to 35%, and the addition amount is Cr (VI) in the liquid after reduction. 100% of the theoretical addition amount so that the concentration is 5% or less of the total Cr amount.
As described above, the method for producing basic chromium sulfate used in chromium-based electroplating is characterized by being 250% or less.
元剤により還元してクロム系電気めっきに使用する塩基
性硫酸クロムを製造する方法において、含有するＳＯ4
とＣｒのモル比を１．１以上、１．４以下とし、前記還
元剤として糖類またはアルコール類の有機系還元剤を用
いて、三酸化クロムの理論添加量に対する８０％以下の
範囲で還元した後に、過酸化水素を還元後の液中のＣｒ
（VI）の濃度が全Ｃｒ量の５％以下になるような添加量
で添加することを特徴とするクロム系電気めっきに使用
する塩基性硫酸クロムの製造方法。3. A method for producing a basic chromium sulfate for use in chromium-based electroplating by reducing an aqueous solution of chromium trioxide with a reducing agent in the presence of sulfuric acid, containing SO 4
The molar ratio of Cr to Cr is 1.1 or more and 1.4 or less, and an organic reducing agent such as saccharide or alcohol is used as the reducing agent, and reduction is performed within a range of 80% or less with respect to the theoretical addition amount of chromium trioxide. Later, Cr in the liquid after reducing hydrogen peroxide
A method for producing basic chromium sulfate for use in chromium-based electroplating, characterized in that the addition amount of (VI) is 5% or less of the total Cr amount.
１時間以上保持することを特徴とする請求項１〜請求項
３のいずれか１項に記載のクロム系電気めっきに使用す
る塩基性硫酸クロムの製造方法。4. The base used for chromium-based electroplating according to claim 1, wherein the reaction liquid after addition of the reducing agent is kept at 100 ° C. or higher for 1 hour or longer. Of producing soluble chromium sulfate.
元剤により還元してクロム系電気めっきに使用する塩基
性硫酸クロムを製造する方法において、含有するＳＯ4
とＣｒのモル比を１．１以上、１．４以下とし、前記還
元剤として糖類を用い、その添加量を還元後の液中のＣ
ｒ（VI）の濃度が全Ｃｒ量の５％以下になるように、理
論添加量の８０％以上、１００％以下とし、還元剤添加
後の反応液を１００℃以上で１時間以上保持することを
特徴とするクロム系電気めっきに使用する塩基性硫酸ク
ロムの製造方法。5. A method for producing basic chromium sulfate for use in chromium-based electroplating by reducing an aqueous solution of chromium trioxide with a reducing agent in the presence of sulfuric acid, containing SO 4
The molar ratio of Cr to Cr is 1.1 or more and 1.4 or less, saccharide is used as the reducing agent, and the addition amount is C in the liquid after reduction.
80% or more and 100% or less of the theoretical addition amount so that the concentration of r (VI) is 5% or less of the total Cr amount, and the reaction liquid after addition of the reducing agent is kept at 100 ° C. or more for 1 hour or more. And a method for producing basic chromium sulfate used in chromium-based electroplating.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP22975594A JPH0891842A (en) | 1994-09-26 | 1994-09-26 | Production of basic chromium sulfate to be used for chromium system electroplating |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP22975594A JPH0891842A (en) | 1994-09-26 | 1994-09-26 | Production of basic chromium sulfate to be used for chromium system electroplating |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0891842A true JPH0891842A (en) | 1996-04-09 |
Family
ID=16897179
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP22975594A Withdrawn JPH0891842A (en) | 1994-09-26 | 1994-09-26 | Production of basic chromium sulfate to be used for chromium system electroplating |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0891842A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2010026916A1 (en) * | 2008-09-05 | 2010-03-11 | 日本化学工業株式会社 | Chromium(iii)-containing aqueous solution and process for production of same |
| WO2010037532A1 (en) | 2008-10-01 | 2010-04-08 | Voestalpine Stahl Gmbh | Method for the electrolytic deposition of chromium and chromium alloys |
| JP5529024B2 (en) * | 2008-09-05 | 2014-06-25 | 日本化学工業株式会社 | Chromium (III) carbonate and method for producing the same |
| CN105734631A (en) * | 2014-12-10 | 2016-07-06 | 上海宝钢工业技术服务有限公司 | Electroplating solution and electroplating method for roughening treatment of cold-rolled roller |
| CN109399714A (en) * | 2018-12-29 | 2019-03-01 | 长沙兴嘉生物工程股份有限公司 | A method of chromium sulfate basic is prepared with chromate waste water |
-
1994
- 1994-09-26 JP JP22975594A patent/JPH0891842A/en not_active Withdrawn
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2010026916A1 (en) * | 2008-09-05 | 2010-03-11 | 日本化学工業株式会社 | Chromium(iii)-containing aqueous solution and process for production of same |
| JP5518718B2 (en) * | 2008-09-05 | 2014-06-11 | 日本化学工業株式会社 | Method for producing aqueous solution containing chromium (III) |
| JP5529024B2 (en) * | 2008-09-05 | 2014-06-25 | 日本化学工業株式会社 | Chromium (III) carbonate and method for producing the same |
| WO2010037532A1 (en) | 2008-10-01 | 2010-04-08 | Voestalpine Stahl Gmbh | Method for the electrolytic deposition of chromium and chromium alloys |
| DE102008050034A1 (en) | 2008-10-01 | 2010-04-15 | Voestalpine Stahl Gmbh | Process for the electrolytic deposition of chromium and chromium alloys |
| DE102008050034B4 (en) * | 2008-10-01 | 2013-02-21 | Voestalpine Stahl Gmbh | Process for the electrolytic deposition of chromium and chromium alloys |
| CN105734631A (en) * | 2014-12-10 | 2016-07-06 | 上海宝钢工业技术服务有限公司 | Electroplating solution and electroplating method for roughening treatment of cold-rolled roller |
| CN105734631B (en) * | 2014-12-10 | 2019-03-19 | 上海宝钢工业技术服务有限公司 | The electro-plating method of roll for cold rolling frosting treatment |
| CN109399714A (en) * | 2018-12-29 | 2019-03-01 | 长沙兴嘉生物工程股份有限公司 | A method of chromium sulfate basic is prepared with chromate waste water |
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