JP4667084B2 - Chromium ion replenishment method for trivalent chromium plating bath - Google Patents
Chromium ion replenishment method for trivalent chromium plating bath Download PDFInfo
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- JP4667084B2 JP4667084B2 JP2005069049A JP2005069049A JP4667084B2 JP 4667084 B2 JP4667084 B2 JP 4667084B2 JP 2005069049 A JP2005069049 A JP 2005069049A JP 2005069049 A JP2005069049 A JP 2005069049A JP 4667084 B2 JP4667084 B2 JP 4667084B2
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- 238000007747 plating Methods 0.000 title claims description 137
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 title claims description 82
- 239000011651 chromium Substances 0.000 title claims description 74
- 229910052804 chromium Inorganic materials 0.000 title claims description 71
- 229910001430 chromium ion Inorganic materials 0.000 title claims description 33
- 238000000034 method Methods 0.000 title claims description 17
- VQWFNAGFNGABOH-UHFFFAOYSA-K chromium(iii) hydroxide Chemical compound [OH-].[OH-].[OH-].[Cr+3] VQWFNAGFNGABOH-UHFFFAOYSA-K 0.000 claims description 61
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonia chloride Chemical compound [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 claims description 14
- DHMQDGOQFOQNFH-UHFFFAOYSA-N Glycine Chemical compound NCC(O)=O DHMQDGOQFOQNFH-UHFFFAOYSA-N 0.000 claims description 14
- 238000004090 dissolution Methods 0.000 claims description 13
- 229910021555 Chromium Chloride Inorganic materials 0.000 claims description 12
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 12
- QSWDMMVNRMROPK-UHFFFAOYSA-K chromium(3+) trichloride Chemical compound [Cl-].[Cl-].[Cl-].[Cr+3] QSWDMMVNRMROPK-UHFFFAOYSA-K 0.000 claims description 12
- 239000000499 gel Substances 0.000 claims description 11
- 238000004519 manufacturing process Methods 0.000 claims description 9
- 239000000203 mixture Substances 0.000 claims description 8
- 239000004471 Glycine Substances 0.000 claims description 7
- 235000019270 ammonium chloride Nutrition 0.000 claims description 7
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 claims description 7
- 238000004070 electrodeposition Methods 0.000 claims description 6
- 238000003860 storage Methods 0.000 claims description 6
- 239000000017 hydrogel Substances 0.000 claims description 5
- 239000002585 base Substances 0.000 claims description 4
- GRWVQDDAKZFPFI-UHFFFAOYSA-H chromium(III) sulfate Chemical compound [Cr+3].[Cr+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O GRWVQDDAKZFPFI-UHFFFAOYSA-H 0.000 claims description 4
- 229910052500 inorganic mineral Inorganic materials 0.000 claims description 4
- 239000011707 mineral Substances 0.000 claims description 4
- 150000003839 salts Chemical class 0.000 claims description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 3
- 229910052799 carbon Inorganic materials 0.000 claims description 3
- UUWCBFKLGFQDME-UHFFFAOYSA-N platinum titanium Chemical compound [Ti].[Pt] UUWCBFKLGFQDME-UHFFFAOYSA-N 0.000 claims description 3
- JGDITNMASUZKPW-UHFFFAOYSA-K aluminium trichloride hexahydrate Chemical compound O.O.O.O.O.O.Cl[Al](Cl)Cl JGDITNMASUZKPW-UHFFFAOYSA-K 0.000 claims description 2
- 229940009861 aluminum chloride hexahydrate Drugs 0.000 claims description 2
- 229940035427 chromium oxide Drugs 0.000 claims description 2
- 229910000423 chromium oxide Inorganic materials 0.000 claims description 2
- LJAOOBNHPFKCDR-UHFFFAOYSA-K chromium(3+) trichloride hexahydrate Chemical compound O.O.O.O.O.O.[Cl-].[Cl-].[Cl-].[Cr+3] LJAOOBNHPFKCDR-UHFFFAOYSA-K 0.000 claims description 2
- 238000011065 in-situ storage Methods 0.000 claims description 2
- 150000002500 ions Chemical class 0.000 claims description 2
- 239000007788 liquid Substances 0.000 claims description 2
- 125000000896 monocarboxylic acid group Chemical group 0.000 claims description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 6
- VSCWAEJMTAWNJL-UHFFFAOYSA-K aluminium trichloride Chemical compound Cl[Al](Cl)Cl VSCWAEJMTAWNJL-UHFFFAOYSA-K 0.000 description 6
- JOPOVCBBYLSVDA-UHFFFAOYSA-N chromium(6+) Chemical compound [Cr+6] JOPOVCBBYLSVDA-UHFFFAOYSA-N 0.000 description 6
- 239000004327 boric acid Substances 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- 239000000460 chlorine Substances 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 229940063656 aluminum chloride Drugs 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 229910052801 chlorine Inorganic materials 0.000 description 3
- -1 chlorine ions Chemical class 0.000 description 3
- 238000005868 electrolysis reaction Methods 0.000 description 3
- 239000002244 precipitate Substances 0.000 description 3
- 239000011780 sodium chloride Substances 0.000 description 3
- KZBUYRJDOAKODT-UHFFFAOYSA-N Chlorine Chemical compound ClCl KZBUYRJDOAKODT-UHFFFAOYSA-N 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 231100000053 low toxicity Toxicity 0.000 description 2
- 238000007639 printing Methods 0.000 description 2
- 238000005096 rolling process Methods 0.000 description 2
- 231100000419 toxicity Toxicity 0.000 description 2
- 230000001988 toxicity Effects 0.000 description 2
- LSNNMFCWUKXFEE-UHFFFAOYSA-M Bisulfite Chemical compound OS([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-M 0.000 description 1
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 1
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- 239000010405 anode material Substances 0.000 description 1
- KRVSOGSZCMJSLX-UHFFFAOYSA-L chromic acid Substances O[Cr](O)(=O)=O KRVSOGSZCMJSLX-UHFFFAOYSA-L 0.000 description 1
- 239000008139 complexing agent Substances 0.000 description 1
- 238000005034 decoration Methods 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000007667 floating Methods 0.000 description 1
- 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 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 239000002932 luster Substances 0.000 description 1
- 238000007726 management method Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 229910052938 sodium sulfate Inorganic materials 0.000 description 1
- 235000011152 sodium sulphate Nutrition 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 239000006228 supernatant Substances 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
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Description
本発明はクロムめっき技術に関するものである。 The present invention relates to chromium plating technology.
クロムめっきは装飾用および工業用として多くの産業分野で使われている。クロムめっきは大気中で腐食せず光沢を失わないために装飾用として広く使われると共に、高い硬度と低い摩擦係数を有するために耐摩耗性を要する機械部品等に広く用いられている。しかしながら、このめっきに使われるめっき液には多量の有害な６価クロムが使われるために、毒性の少ないめっき液の開発が強く望まれている。 Chrome plating is used in many industrial fields for decorative and industrial purposes. Chromium plating is widely used for decoration because it does not corrode in the atmosphere and does not lose its luster, and is also widely used for mechanical parts that require high wear resistance due to its high hardness and low coefficient of friction. However, since a large amount of harmful hexavalent chromium is used for the plating solution used in this plating, development of a plating solution with low toxicity is strongly desired.
本発明のクロムめっきは毒性の少ない３価クロムを用いるため、従来の自動車やオートバイ等の機械部品や各種金型、印刷や圧延ロール等のクロムめっきに利用が期待される。 Since the chromium plating of the present invention uses trivalent chromium with little toxicity, it is expected to be used for chromium plating of conventional machine parts such as automobiles and motorcycles, various dies, printing and rolling rolls.
これまでクロムめっきは６価クロムを含むサージェント浴と呼ばれるめっき液やフツ化物や有機スルフォン酸を含む６価クロム浴等により行われている。特公昭５７−１１３９６及び特開昭５６−１１２４９３に記載されているように、３価クロム浴による装飾クロムめっきは実用化されるようになったが、クロム酸を多量に使用する工業用クロムめっきの分野では浴寿命などに問題があり、工業用として使用できる３価クロム浴は未だに開発されていない。 Until now, chromium plating has been performed by a plating solution called a sergeant bath containing hexavalent chromium, a hexavalent chromium bath containing fluoride, or organic sulfonic acid. As described in Japanese Patent Publication No. 57-11396 and Japanese Patent Application Laid-Open No. 56-112493, decorative chrome plating using a trivalent chrome bath has come into practical use, but industrial chrome plating using a large amount of chromic acid. In this field, there is a problem in bath life and the like, and a trivalent chromium bath that can be used for industrial use has not been developed yet.
発明者らはグリシンを錯化剤とし、これにホウ酸や塩化アンモニウム、塩化アルミニウムを含む３価クロム浴から厚いクロムめっきが得られることを見出した。しかし、この浴で長時間めっきを行なうとクロムイオンが析出して消耗するので、その補給に塩化クロムや硫酸クロム等を使用すると液中に塩素イオンや硫酸イオンが増大し、ついにはめっき不能となる。そこで発明者らはクロムイオンの補給に水酸化クロムを使用することを提案した［２００４年春の国際クロム会議（フランス）］。 The inventors have found that thick chromium plating can be obtained from a trivalent chromium bath containing glycine as a complexing agent and containing boric acid, ammonium chloride, and aluminum chloride. However, if plating is performed for a long time in this bath, chromium ions are deposited and consumed, so using chromium chloride, chromium sulfate, etc. for replenishment increases chlorine ions and sulfate ions in the liquid, and eventually plating is impossible. Become. The inventors therefore proposed using chromium hydroxide to supplement chromium ions [International Chromium Conference in Spring 2004 (France)].
その後の研究で水酸化クロムを直接めっき液に投入して長時間めっきすると種々の問題が生じることがわかった。すなわち、市販の水酸化クロム製品はめっき液に溶け難く、未溶解の固形水酸化クロムがめっき液中に浮遊状態で残ってしまうので、これがめっき面に付きめっき不良の原因となる。このため３価クロムめっき法は工業化が困難なままである。 Subsequent research has revealed that various problems occur when chromium hydroxide is added directly to the plating solution and plated for a long time. That is, a commercially available chromium hydroxide product is difficult to dissolve in the plating solution, and undissolved solid chromium hydroxide remains in the plating solution in a floating state, which is attached to the plating surface and causes defective plating. For this reason, the industrialization of the trivalent chromium plating method remains difficult.
本発明は従来のクロムめっきに使われている有害な６価クロムを使わないクロムめっき法に関するものである。すなわち、クロムめっき工場で働く従業員の健康を損なわないクロムめっき液を提供し、また、火災や地震、不慮の事故等によるめっき液の流失の際にも公害を引き起こす恐れがない、環境に優しい実用的な３価クロムめっき方法を提供しようとするものである。しかし、前項で述べたように、これまで３価クロムめっきに関して、実用的なめっき液は開発されていない。 The present invention relates to a chromium plating method that does not use harmful hexavalent chromium used in conventional chromium plating. In other words, it provides a chromium plating solution that does not impair the health of employees working in the chrome plating factory, and is environmentally friendly, with no risk of causing pollution in the event of a plating solution loss due to a fire, earthquake, or accident. It is intended to provide a practical trivalent chromium plating method. However, as described in the previous section, no practical plating solution has been developed for trivalent chromium plating.
本発明のクロムめっき法は毒性の少ない３価クロムを長期間にわたって使用するためのめっき液へのクロムイオンの補給法を解決するものである。従って、この方法は、現在、毒性が問題となっている６価クロムめっき浴の代替用のめっき液を提供することを可能とするので、自動車やオートバイ等の機械部品や各種金型、印刷や圧延ロール等のクロムめっきに利用が期待される。 The chromium plating method of the present invention solves the method of supplying chromium ions to a plating solution for using trivalent chromium with low toxicity for a long period of time. Therefore, this method makes it possible to provide a plating solution for replacing the hexavalent chromium plating bath whose toxicity is a problem at present, so that mechanical parts such as automobiles and motorcycles, various molds, printing, It is expected to be used for chromium plating of rolling rolls.
有害な６価クロムを使わないめっき液として３価クロム浴は長い間研究されてきたが、めっきを行いながら長期間めっき液の組成を一定に保つ事は困難であり、そのようなめっき液組成やその管理法はこれまで確立されていない。本発明ではこれらの点を解決したものである。 Trivalent chromium baths have been studied for a long time as a plating solution that does not use harmful hexavalent chromium, but it is difficult to keep the composition of the plating solution constant for a long time while performing plating. No management method has been established so far. The present invention solves these points.
すなわち本発明は、
３価クロムめっき浴に、電析により消耗したクロムイオンを補給するにあたり、
（１）水酸化クロムを使ってクロムイオンを補給すること、
（２）水酸化クロムとして、含水ゲルの形状のものを使うこと、そして
（３）めっき液の一部分を取出し、これに水酸化クロム含水ゲルを混合し、溶解させそしてろ過することにより製造したクロムイオン補給液を、めっき液に戻すこと、
を特徴とする、３価クロムめっき浴に、電析により消耗したクロムイオンを補給する、クロムイオン補給方法
を提供するものである。
That is, the present invention
In replenishing chromium ions consumed by electrodeposition to a trivalent chromium plating bath,
(1) Supply chromium ions using chromium hydroxide,
(2) Use chromium hydroxide in the form of a hydrous gel, and (3) remove a part of the plating solution, mix the chromium hydrous gel with this, dissolve and filter the chromium. Returning the ion replenisher to the plating solution,
A chromium ion replenishing method is provided that replenishes chromium ions consumed by electrodeposition in a trivalent chromium plating bath.
水酸化クロム含水ゲルとして、その場で、３価クロムの鉱酸塩と塩基との反応により製造したものを使うことが、好ましい。３価クロムの鉱酸塩として塩化クロム又は硫酸クロムを使い、塩基として水酸化ナトリウムを使うことができる。 As the chromium hydroxide hydrous gel, it is preferable to use a gel prepared by a reaction of a trivalent chromium mineral salt with a base in situ. Chromium chloride or chromium sulfate can be used as a mineral salt of trivalent chromium, and sodium hydroxide can be used as a base.
また本発明は、３価クロムめっき浴と、めっき液の一部分に水酸化クロム含水ゲルを混合し、溶解させそしてろ過するクロムイオン補給液製造装置と、３価クロムめっき浴とクロムイオン補給液製造装置との間を結ぶめっき液循環管路とを含んで成る、３価クロムめっき装置を提供する。 The present invention also provides a trivalent chromium plating bath, a chromium ion replenisher manufacturing apparatus that mixes, dissolves and filters a chromium hydroxide-containing gel in a part of the plating solution, a trivalent chromium plating bath, and a chromium ion replenisher. There is provided a trivalent chromium plating apparatus including a plating solution circulation line connecting between the apparatuses.
クロムイオン補給液製造装置として、水酸化クロム含水ゲルを製造する水酸化クロム生成槽と、製造した水酸化クロム含水ゲルを貯蔵する水酸化クロム貯蔵槽と、めっき液の一部分に貯蔵した水酸化クロム含水ゲルを混合し、溶解させそしてろ過する水酸化クロム溶解槽とを含み、めっき液循環管路として、３価クロムめっき浴と水酸化クロム溶解槽との間を結ぶめっき液循環管路とを含んで成る、３価クロムめっき装置が好ましい。 As a chromium ion replenisher solution production apparatus, a chromium hydroxide production tank for producing a chromium hydroxide hydrogel, a chromium hydroxide storage tank for storing the produced chromium hydroxide hydrogel, and a chromium hydroxide stored in a part of the plating solution A plating solution circulation line connecting the trivalent chromium plating bath and the chromium hydroxide dissolution tank as a plating solution circulation line. The trivalent chromium plating apparatus comprising is preferable.
本発明の好ましい実施態様には、塩化クロム、グリシン、ホウ酸及び塩化アンモニウムを含んで成るめっき液を用いて３価クロムめっきするにあたり、めっき液の一部を水酸化クロムの溶解槽に導き、この溶解槽において水酸化クロムをめっき液に溶解させることにより、電析で消耗するめっき液中のクロムイオン濃度を制御しながらめっきする、３価クロムめっき方法が含まれる。 In a preferred embodiment of the present invention, when trivalent chromium plating is performed using a plating solution containing chromium chloride, glycine, boric acid and ammonium chloride, a part of the plating solution is led to a chromium hydroxide dissolution tank, A trivalent chromium plating method of plating while controlling the chromium ion concentration in the plating solution consumed by electrodeposition by dissolving chromium hydroxide in the plating solution in this dissolution tank is included.
ここで、クロムイオンの供給源である水酸化クロムは予め水酸化クロム生成槽で作成する。この槽には塩化クロムや硫酸クロムの溶液を導入し、これに水酸化クロムを生成させるに十分な水酸化ナトリウム溶液を注入し、水酸化クロムを沈殿させる。この沈殿を良く水洗し反応で生成した溶液中の塩化ナトリウムや硫酸ナトリウムを除去し、含水率の高いゲル状の水酸化クロムを準備する。 Here, chromium hydroxide as a supply source of chromium ions is prepared in advance in a chromium hydroxide generation tank. Into this tank, a solution of chromium chloride or chromium sulfate is introduced, and a sodium hydroxide solution sufficient to produce chromium hydroxide is injected into the tank to precipitate chromium hydroxide. This precipitate is washed well with water to remove sodium chloride and sodium sulfate in the solution produced by the reaction, and gel-like chromium hydroxide having a high water content is prepared.
次いで、陰極におけるクロムの析出に伴うめっき液中のクロムイオンの消耗に応じて、めっき液に水酸化クロムの溶解槽からクロムイオンを補給しながらめっきすることにより、長時間連続運転が可能となる。 Next, depending on the consumption of chromium ions in the plating solution accompanying the deposition of chromium at the cathode, plating can be performed while supplying chromium ions from the chromium hydroxide dissolution tank to the plating solution, thereby enabling continuous operation for a long time. .
水酸化クロムを溶解槽でめっき液に溶解する際に、一部は溶解せずに長い時間めっき液中に浮遊するものがあるので、フィルターを通してろ過してから、めっき液に戻す。 When chromium hydroxide is dissolved in the plating solution in the dissolution tank, there is a part that does not dissolve but floats in the plating solution for a long time, so it is filtered through a filter and then returned to the plating solution.
ここで、３価クロムめっき浴として、次の組成
塩化クロム６水和物［ＣｒＣｌ３・６Ｈ２Ｏ］ １００〜３００ｇ／Ｌ
ホウ酸［Ｈ３ＢＯ３］ ２０〜３０ｇ／Ｌ
グリシン［ＮＨ２ＣＨ２ＣＯＯＨ］ ３０〜５０ｇ／Ｌ
塩化アンモニウム［ＮＨ４Ｃｌ］ ７０〜１５０ｇ／Ｌ
塩化アルミニウム６水和物［ＡｌＣｌ３・６Ｈ２Ｏ］ ２０ｇ／Ｌ
の浴を使うことが好ましい。
Here, as a trivalent chromium plating bath, the following composition
Chromium chloride hexahydrate [CrCl 3 · 6H 2 O] 100~300g / L
Boric acid [H 3 BO 3 ] 20-30 g / L
Glycine [NH 2 CH 2 COOH] 30-50 g / L
Ammonium chloride [NH 4 Cl] 70-150 g / L
Aluminum chloride hexahydrate [AlCl 3 · 6H 2 O] 20g / L
It is preferable to use a bath of
また、めっきは次の条件
電流密度 ２０〜８０Ａ／ｄｍ２
浴温 ３５〜６５℃
陽極 炭素板又はチタン−白金板
の下で行うことが好ましい。
In addition, plating is as follows
Current density 20-80 A / dm 2
Bath temperature 35-65 ° C
Anode Carbon plate or Titanium-platinum plate
Is preferably carried out under
また、本発明の好ましい実施態様には、めっき槽と、フィルターを備えた水酸化クロム溶解槽とを結ぶめっき液循環管路とを含んで成る、３価クロムめっき装置が含まれる。 Further, a preferred embodiment of the present invention includes a trivalent chromium plating apparatus including a plating tank and a plating solution circulation pipe connecting a chromium hydroxide dissolution tank provided with a filter.
ここで、めっき液は溶解槽中のフィルターの手前に供給し、フィルターを通過した補給液をめっき液に戻すように管路を形成する。 Here, the plating solution is supplied to the front of the filter in the dissolution tank, and a conduit is formed so that the replenishing solution that has passed through the filter is returned to the plating solution.
陽極材料として炭素（カーボン）を使うことが好ましいが、チタン‐白金板を使うことも可能である。 It is preferable to use carbon as the anode material, but it is also possible to use a titanium-platinum plate.
本発明者は、塩化クロムを多量に含む３価クロム浴でめっきを行うと金属クロムイオン濃度が減少するので、これを補給するために塩化クロムを添加すると塩素イオンが浴中に増加し、陽極から有害な塩素ガスが発生することを実験的に見出した。本発明はこれをきっかけとして成された。まず、電解中に陰極で電析消耗する金属クロムイオンの量を、含水ゲルの形状の水酸化クロムの添加により補充する。そして次に、溶解しきれない水酸化クロムがめっき液中に入りめっき面に付着して不めっき部を生じること（めっき不良）を防ぐために、フィルターを通してめっき液に戻す。こうして、めっきの質の確保とめっき液の組成を一定に保つことが出来るのではないかと考え、これを実験により確認した。 When the present inventors perform plating in a trivalent chromium bath containing a large amount of chromium chloride, the metal chromium ion concentration decreases. Therefore, when chromium chloride is added to replenish this, chlorine ions increase in the bath, and the anode We have experimentally found that harmful chlorine gas is generated. This invention was made using this as a trigger. First, the amount of metallic chromium ions that are electrodeposited and consumed at the cathode during electrolysis is supplemented by the addition of chromium hydroxide in the form of a hydrous gel. Then, in order to prevent chromium hydroxide, which cannot be completely dissolved, from entering the plating solution and adhering to the plating surface to form an unplated part (plating failure), the solution is returned to the plating solution through a filter. Thus, it was thought that the quality of plating and the composition of the plating solution could be kept constant, and this was confirmed by experiments.
この結果、めっき液の組成を長期間にわたり一定に保つことが可能になり、硬質クロムのような厚付け用のクロムめっきを可能とする３価クロムめっき方法の開発に成功したのである。 As a result, the composition of the plating solution can be kept constant over a long period of time, and the development of a trivalent chromium plating method that enables thick chromium plating such as hard chromium has been successfully developed.
なお、３価クロム浴中の金属クロムイオンを補給しないでめっきを続けると、めっき液中に塩素イオンが過剰となり、陽極で有害な塩素ガスが発生するのでクロムイオン濃度を一定に保つことは環境面からも重要である。 If plating is continued without supplying metallic chromium ions in the trivalent chromium bath, chlorine ions will become excessive in the plating solution, and harmful chlorine gas will be generated at the anode. It is also important from the aspect.
以下に本発明の実施例を示し更に詳細に説明する。
図１は、本発明による３価クロムめっき浴への金属クロムイオン供給システムの一例を示したものである。本発明では電析した金属クロム分の補給に水酸化クロムを用いるが、市販されているような含水率の低い水酸化クロムを直接めっき浴に添加すると溶解に時間がかかるので含水率の高いゲル状の水酸化クロムを用意する。先ず、水酸化クロム生成槽１に塩化クロム溶液を入れ、これに含まれる全てのクロムイオンを水酸化クロムにするに要する水酸化ナトリウム溶液（式（１）参照）を添加し沈殿させる。この反応の終点は液のｐＨの変化により知ることができる。次いで沈殿の上澄み液を廃棄してから、これに水を加え沈殿した水酸化クロムを洗浄し、溶存する塩化ナトリウム分を除去する。この操作を繰り返して塩化ナトリウム分を除去したゲル状の水酸化クロムを水酸化クロム貯蔵槽２に入れ保存する。めっき作業によりクロムめっき槽４から析出したクロム分に相当する量の水酸化クロムを水酸化クロム貯蔵槽２から取り出し、水酸化クロム溶解槽３に入れる。この水酸化クロム溶解槽３にはクロムめっき槽４からめっき液が導入され、攪拌しながら水酸化クロムを溶解させる。水酸化クロムを溶解しためっき液はフィルター５を通過してクロムめっき槽４に戻される。ここでフィルター５を通過させるのは未溶解の水酸化クロムが残ったままめっき槽に入ると、これがめっき面に付着しめっき不良の原因となるからである。
ＣｒＣｌ３＋３ＮａＯＨ → Ｃｒ（ＯＨ）３＋３ＮａＣｌ （１）
Hereinafter, examples of the present invention will be shown and described in more detail.
FIG. 1 shows an example of a metal chromium ion supply system to a trivalent chromium plating bath according to the present invention. In the present invention, chromium hydroxide is used for replenishing the deposited metal chromium. However, it takes a long time to dissolve the chromium hydroxide with a low water content, such as a commercially available gel, so that the gel has a high water content. A chrome hydroxide is prepared. First, a chromium chloride solution is placed in the chromium
CrCl 3 + 3NaOH → Cr (OH) 3 + 3NaCl (1)
実施例１
図１の装置を用いて、次のめっき浴、すなわち、塩化クロム３００ｇ／１、塩化アンモニウム１３０ｇ／１、グリシン５０ｇ／１、ホウ酸３０ｇ／１、塩化アルミニウム５０ｇ／１を含む３価クロムめっき浴により５０℃、４０Ａ／ｄｍ２の条件で長時間電解を行い、１０万クーロン／Ｌ 通電するたびに水酸化クロムを電析した金属クロムに相当する分だけ溶解槽で溶解させてめっき液に添加してクロムめっきを絶続したところ１００万クーロンの通電でも良好なクロムめっきが得られた。この時のクロムめっきの電流効率は約２０％とほぼ一定値を示した。
Example 1
Using the apparatus shown in FIG. 1, the following plating bath, that is, a trivalent chromium plating bath containing chromium chloride 300 g / 1, ammonium chloride 130 g / 1, glycine 50 g / 1, boric acid 30 g / 1, and aluminum chloride 50 g / 1. Electrolysis is performed for a long time under the conditions of 50 ° C. and 40 A / dm 2 , and every time when 100,000 coulombs / L is applied, chromium hydroxide is dissolved in the dissolution tank by an amount corresponding to the deposited metal chromium and added to the plating solution. When chrome plating was continued, good chrome plating was obtained even with a current of 1 million coulombs. At this time, the current efficiency of the chromium plating was approximately 20%, which was a substantially constant value.
この時のクロム電析の電流効率（２０％）から計算するとクロムめっきの析出量は１０万クーロン／Ｌ当り約３．５グラムであった。そこで水酸化クロム貯蔵槽２からこれに相当する水酸化クロムを取り出して水酸化クロム溶解槽３に入れ、めっき液からポンプＰで送入されたクロムめっき液に溶解しフィルターを通してクロムめっき槽４に戻したところ、めっき液中の塩化クロム濃度はめっき前の３００ｇ／Ｌに回復した。このような作業を繰り返し、１００万クーロン／Ｌの長時間めっきに成功した。
When calculated from the current efficiency (20%) of chromium electrodeposition at this time, the amount of chromium plating deposited was about 3.5 grams per 100,000 coulomb / L. Therefore, the corresponding chromium hydroxide is taken out from the chromium
なお、この浴でクロム分を添加せずにめっきを続けると約２０万クーロンでめっきが付かなくなった。 If plating was continued without adding chromium in this bath, plating could not be applied at about 200,000 coulombs.
実施例２
図１の装置と次のような３価クロムめっき液、すなわち、塩化クロム２００ｇ／Ｌ、塩化アンモニウム１１０ｇ／Ｌ、グリシン５０ｇ／Ｌ、ホウ酸３０ｇ／Ｌを含む３価クロムめっき浴を用いて、電流密度４０Ａ／ｄｍ２、めっき液の温度５０℃とし、実施例１と同じ方法でめっき電流の通電量１０万クーロン毎に電析したクロム金属相当分の水酸化クロムをめっき液に溶解させて添加しながら連続してクロムめっきを行なったところ２００万クーロン/Lを過ぎてもめっきが可能であった。
Example 2
1 and the following trivalent chromium plating solution, that is, a trivalent chromium plating bath containing 200 g / L of chromium chloride, 110 g / L of ammonium chloride, 50 g / L of glycine, and 30 g / L of boric acid, Chromium hydroxide equivalent to chromium metal electrodeposited every 100,000 coulombs of plating current by the same method as in Example 1 with a current density of 40 A / dm 2 and a plating solution temperature of 50 ° C. was dissolved in the plating solution. When chromium plating was performed continuously while adding, plating was possible even after passing over 2 million coulomb / L.
実施例３
図１の装置で次のような組成、すなわち、塩化クロム２５０ｇ／１、塩化アンモニウム１３０ｇ／Ｌ、グリシン５０ｇ／Ｌ、ホウ酸３０ｇ／Ｌ、塩化アルミニウム３０ｇ／Ｌを含む３価クロムめっき浴により４０℃、３５Ａ／ｄｍ２の条件でめっきを行い、予め求めた電流効率から予測されるクロムイオンの減少分に相当する量の水酸化クロムを溶解させながら長時間電解を行い、良好なめっきが得られた。
Example 3
In the apparatus of FIG. 1, the following composition is obtained: 40 by a trivalent chromium plating bath containing 250 g / 1 of chromium chloride, 130 g / L of ammonium chloride, 50 g / L of glycine, 30 g / L of boric acid, and 30 g / L of aluminum chloride. Plating is performed under the conditions of 35 ° C. and 35 A / dm 2 , and electrolysis is performed for a long time while dissolving an amount of chromium hydroxide corresponding to the decrease in chromium ions predicted from the current efficiency obtained in advance, thereby obtaining good plating. It was.
１ 水酸化クロム生成槽
２ 水酸化クロム貯蔵槽
３ 水酸化クロム溶解槽
４ クロムめっき槽
５ フィルター
Ｐ ポンプ
→ めっき液及び水酸化クロムの流れ方向
1 Chromium
Claims (7)
（１）水酸化クロムを使ってクロムイオンを補給すること、
（２）水酸化クロムとして、含水ゲルの形状のものを使うこと、そして
（３）めっき液の一部分を取出し、これに水酸化クロム含水ゲルを混合し、溶解させそしてろ過することにより製造したクロムイオン補給液を、めっき液に戻すこと、
を特徴とする、３価クロムめっき浴に、電析により消耗したクロムイオンを補給する、クロムイオン補給方法。 In replenishing chromium ions consumed by electrodeposition to a trivalent chromium plating bath,
(1) Supply chromium ions using chromium hydroxide,
(2) Use chromium hydroxide in the form of a hydrous gel, and (3) remove a part of the plating solution, mix the chromium hydrous gel with this, dissolve and filter the chromium. Returning the ion replenisher to the plating solution,
A chromium ion replenishment method comprising replenishing chromium ions consumed by electrodeposition to a trivalent chromium plating bath.
塩化クロム６水和物［ＣｒＣｌ３・６Ｈ２Ｏ］ １００〜３００ｇ／Ｌ
ホウ酸［Ｈ３ＢＯ３］ ２０〜３０ｇ／Ｌ
グリシン［ＮＨ２ＣＨ２ＣＯＯＨ］ ３０〜５０ｇ／Ｌ
塩化アンモニウム［ＮＨ４Ｃｌ］ ７０〜１５０ｇ／Ｌ
塩化アルミニウム６水和物［ＡｌＣｌ３・６Ｈ２Ｏ］ ２０〜５０ｇ／Ｌ
の浴を使う、請求項１〜３のいずれかに記載のクロムイオン補給方法。 The following composition as a trivalent chromium plating bath
Chromium chloride hexahydrate [CrCl 3 · 6H 2 O] 100~300g / L
Boric acid [H 3 BO 3 ] 20-30 g / L
Glycine [NH 2 CH 2 COOH] 30-50 g / L
Ammonium chloride [NH 4 Cl] 70-150 g / L
Aluminum chloride hexahydrate [AlCl 3 · 6H 2 O] 20~50g / L
The chromium ion replenishment method according to any one of claims 1 to 3, wherein the bath is used.
電流密度 ２０〜８０Ａ／ｄｍ２
浴温 ３５〜６５℃
陽極 炭素板又はチタン−白金板
の下で行う、請求項１〜４のいずれかに記載のクロムイオン補給方法。 Plating is performed under the following conditions: Current density: 20 to 80 A / dm 2
Bath temperature 35-65 ° C
The chromium ion replenishment method according to any one of claims 1 to 4, which is performed under an anode carbon plate or titanium-platinum plate.
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| JP5207454B2 (en) * | 2008-04-09 | 2013-06-12 | 重夫 星野 | Trivalent chromium plating solution management device |
| 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 |
| JPWO2010026886A1 (en) * | 2008-09-05 | 2012-02-02 | 日本化学工業株式会社 | Method for producing chromium hydroxide |
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| WO2020189802A1 (en) * | 2019-03-15 | 2020-09-24 | 유한회사 한국신기술 | Antioxidant, comprising cyano-carboxy group composite free from sulfur (s) component, for preventing oxidation of trivalent chromium ions to divalent chromium ions, and trivalent chromium electroplating solution comprising same |
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