US20200040477A1 - Plating solution and method for producing plated product - Google Patents

Plating solution and method for producing plated product Download PDF

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Publication number
US20200040477A1
US20200040477A1 US15/576,892 US201715576892A US2020040477A1 US 20200040477 A1 US20200040477 A1 US 20200040477A1 US 201715576892 A US201715576892 A US 201715576892A US 2020040477 A1 US2020040477 A1 US 2020040477A1
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United States
Prior art keywords
plating
mol
concentration
plating solution
less
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Abandoned
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US15/576,892
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English (en)
Inventor
Hidemi Nawafune
Hiroshi Nishiwaki
Toshikazu Murata
Hidehiro YOSHIOKA
Yoshiyuki KAMEGAWA
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Fuso Co Ltd
Techno Roll Co Ltd
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Fuso Company Ltd
Techno Roll Co Ltd
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Assigned to TECHNO ROLL CO., LTD., FUSO COMPANY, LTD. reassignment TECHNO ROLL CO., LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: KAMEGAWA, Yoshiyuki, MURATA, TOSHIKAZU, NAWAFUNE, HIDEMI, NISHIWAKI, HIROSHI, YOSHIOKA, Hidehiro
Publication of US20200040477A1 publication Critical patent/US20200040477A1/en
Abandoned legal-status Critical Current

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    • 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
    • C25D3/04—Electroplating: Baths therefor from solutions of chromium
    • C25D3/06—Electroplating: Baths therefor from solutions of chromium from solutions of trivalent chromium
    • 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
    • C25D3/04—Electroplating: Baths therefor from solutions of chromium
    • C25D3/10—Electroplating: Baths therefor from solutions of chromium characterised by the organic bath constituents used

Definitions

  • the present invention relates to a plating solution and a method for producing a plated product, more specifically, to a plating solution used for trivalent chromium plating and a method for producing a plated product by applying trivalent chromium plating.
  • Patent Literature 1 JP 2000-249340 A
  • trivalent chromium plating is rarely employed in the cases of producing plated products having complex shapes such as dies and thick plated products, though there are some cases of employing trivalent chromium plating in decorative plating or the like where the plating thickness is several ⁇ m. It is therefore an object of the present invention to provide a plating solution for trivalent chromium plating with which plated products equivalent to those produced by hexavalent chromium plating can be produced, so as to enlarge the application range of environmentally friendly plated products.
  • a plating solution containing chromium sulfate in which the concentration of Cr 3+ ions is adjusted to a specific range exhibits a covering power equivalent to that of a plating solution containing hexavalent chromium, so as to accomplish the present invention.
  • the present invention provides a plating solution used for trivalent chromium plating, the plating solution containing chromium sulfate and formic acid at a concentration of Cr 3+ ions of 0.1 mol/L or more and 1 mol/L or less and a concentration of the formic acid of 0.05 mol/L or more and 0.2 mol/L or less.
  • the present invention provides a method for producing a plated product, the method including a plating step of performing electric plating in a plating bath that contains a plating solution containing chromium sulfate, so as to produce the plated product to which trivalent chromium plating is applied by the plating step, wherein the plating solution used in the plating step has a concentration of Cr 3+ ions of 0.1 mol/L or more and 1 mol/L or less, the plating bath has a temperature of 20° C. or more and less than 40° C., and the electric plating is performed at a current density of 2 A/dm 2 or more and 20 A/dm 2 or less.
  • FIG. 1 is a relationship graph between current density and plating thickness in hexavalent chromium plating and trivalent chromium plating disclosed in general literatures or the like.
  • FIG. 2 is a graph showing the relationship between current density and plating thickness in trivalent chromium plating using the plating solution of the present invention.
  • FIG. 3 is a graph showing the results of a Hull cell test using a plating solution of an embodiment.
  • FIG. 4 is a graph showing the measurement results of plating thickness using a fluorescent x-ray film thickness meter.
  • FIG. 5 is a graph showing the results of a Hull cell test using a plating solution of another embodiment.
  • FIG. 6 is a graph showing the measurement results of plating thickness using a fluorescent x-ray film thickness meter.
  • FIG. 7 is a graph showing the results of a Hull cell test using a plating solution of another embodiment.
  • FIG. 8 is a graph showing the results of a Hull cell test using a plating solution of another embodiment.
  • FIG. 9 is a graph showing the results of a Hull cell test using a plating solution of another embodiment.
  • FIG. 10 is a graph showing the results of a Hull cell test using a plating solution of another embodiment.
  • FIG. 11 is a graph showing the results of a Hull cell test using a plating solution of another embodiment.
  • a method for producing a plated product will be described.
  • a pretreatment step of adjusting the surface properties of a product that serves as an object to be plated (which will be hereinafter referred to also as “original product”) and a plating step of applying trivalent chromium plating to the pre-treated original product (which will be hereinafter referred to also as “pre-treated product”) are performed.
  • a base plating step of applying base plating to the pre-treated product or an intermediate plating step of further applying intermediate plating to the pre-treated product to which base plating has been applied may be performed between the pretreatment step and the plating step, as needed.
  • base plated product trivalent chromium plating is performed as finish plating to the product to which the intermediate plating has been applied (which will be hereinafter referred to also as “intermediate plated product”).
  • chemical surface treatment, heat treatment, or the like may be further applied to the product to which trivalent chromium plating has been applied in the plating step. Further, coating such as clear coating may be applied to the plated product, as needed.
  • Examples of the original product to which the pretreatment step is applied include resin products, ceramic products, metal products, composite products combining resin parts and metal parts, and composite products obtained by coating metal parts with ceramics.
  • Examples of the resins forming the original product include common thermoplastic resins and common thermosetting resins.
  • the resins may be fiber reinforced plastic (FRP).
  • Examples of the ceramics forming the original product include common ceramics mainly containing silicon oxide, aluminum oxide, or the like. Examples of the ceramics also include glassy materials such as enamels.
  • Examples of the metals forming the original product include common metals such as iron and copper.
  • the metals may be alloys.
  • Examples of the pretreatment applied to the original product include polishing such as mechanical polishing, honing, and blasting, and degreasing such as alkali degreasing.
  • polishing such as mechanical polishing, honing, and blasting
  • degreasing such as alkali degreasing.
  • various types of plating such as nickel plating, copper plating, and iron plating with a thickness of several ⁇ m can be applied to the pre-treated product or the base plated product for purposes such as improving the aesthetic appearance and the corrosion resistance of the finish plated product.
  • the plating step of applying trivalent chromium plating electric plating is performed using the pre-treated product, the base plated product, the intermediate plated product, or the like as a workpiece.
  • trivalent chromium plating is applied to the workpiece using a plating bath that contains a plating solution containing chromium sulfate.
  • the plating solution used in the plating step will be described in detail.
  • the plating solution can contain a complexing agent, a pH buffer, a conductive agent, a surfactant, or the like, in addition to chromium sulfate as the main component.
  • water that serves as the solvent of the plating solution include industrial water, tap water, deionized water, distilled water, and pure water.
  • the chromium sulfate is contained in the plating solution so that the concentration of Cr 3+ ions in the plating bath is 0.1 mol/L or more and 1 mol/L or less.
  • the chromium sulfate is preferably contained in the plating solution so that the concentration of Cr 3+ ions in the plating bath is 0.1 mol/L or more and 0.3 mol/L or less. Use of such a preferable plating solution can give better covering power in trivalent chromium plating on the workpiece in the plating step.
  • the chromium sulfate contained in the plating solution of this embodiment as a supply source of the Cr 3+ ions with one or more selected from the group consisting of chromium chloride, basic chromium sulfate, chrome alum, and chromium nitrate
  • the ratio of chromium sulfate in the supply source of the Cr 3+ ions in the plating solution is preferably 90 mol % or more.
  • the ratio of chromium sulfate is more preferably 95 mol % or more, further preferably 99 mol % or more. It is particularly preferable that the supply source of the Cr 3+ ions in the plating solution be substantially only chromium sulfate.
  • organic acids and salts thereof can be used as the complexing agent contained in the plating solution of this embodiment.
  • organic acids include oxalic acid, citric acid, formic acid, maleic acid, malonic acid, tartaric acid, malic acid, acetic acid, phthalic acid, propionic acid, and ethylenediamine tetraacetic acid.
  • salts thereof include alkali metal salts such as lithium salts, potassium salts, and sodium salts, and alkaline earth metal salts such as magnesium salts and calcium salts.
  • the formic acid is a particularly effective component as the complexing agent, and it is important that the formic acid be contained in the plating solution at a concentration of 0.05 mol/L or more and 0.2 mol/L or less.
  • the concentration of the formic acid in the plating solution is more preferably 0.08 mol/L or more and 0.12 mol/L or less.
  • the aforementioned organic acids and the salts thereof exert at least a certain effect also as the pH buffer.
  • amino carbonyl compounds such as urea and carbamic acid also may be employed.
  • urea functions not only as the pH buffer but also as a supply source of nitrogen to the plating film, which is effective in hardening the film.
  • urea can be expected to have an effect of suppressing generation of a precipitate such as chromium hydroxide in the plating solution.
  • the urea is preferably contained in the plating solution at a concentration of 0.1 mol/L or more and 1 mol/L or less.
  • the concentration of the urea in the plating solution is more preferably 0.2 mol/L or more and 0.8 mol/L or less, particularly preferably 0.4 mol/L or more and 0.6 mol/L or less.
  • examples that are usable as the pH buffer include boric acid and borate.
  • the boric acid is contained in the plating solution
  • the boric acid is generally contained in the plating solution at a concentration of 0.5 mol/L or more and 1 mol/L or less, though it also depends on the amount of the organic acids or the urea contained as the pH buffer.
  • the pH of the plating solution is preferably adjusted to 1 or more and 2 or less, more preferably 1.3 or more and 1.7 or less, using the pH buffer or the like.
  • Examples of the conductive agent include ammonium chloride, sodium chloride, potassium chloride, ammonium sulfate, sodium sulfate, potassium sulfate, ammonium nitrate, sodium nitrate, and potassium nitrate.
  • examples of the surfactant include sodium lauryl sulfate, sodium dodecyl sulfate, polyethylene glycol, diisohexyl sulfosuccinate, 2-ethylhexyl sulfate, diisobutyl sulfosuccinate, diisoamyl sulfosuccinate, and isodecyl sulfosuccinate.
  • various additives including a film forming agent such as polyethylene glycol, polyvinyl alcohol, and gelatin, and a defoamer can be contained as additional additives.
  • a film forming agent such as polyethylene glycol, polyvinyl alcohol, and gelatin
  • a defoamer can be contained as additional additives.
  • the temperature of the plating bath in the plating step is more preferably 23° C. or more and 29° C. or less, particularly preferably 24° C. or more and 28° C. or less.
  • a plating film with uniform thickness and excellent surface brightness can be provided on the finish plated product by performing the plating step under such preferable temperature conditions.
  • the current density is 2 A/dm 2 or more and 20 A/dm 2 or less.
  • the current density is more preferably 2 A/dm 2 or more and 15 A/dm 2 or less, particularly preferably 2 A/dm 2 or more and 13 A/dm 2 or less.
  • the covering power in trivalent chromium plating can be further enhanced by plating the workpiece at such a preferable current density.
  • the workpiece In the plating step, air bubbles are generated in the plating solution due to the hydrogen gas. Therefore, in order to prevent adhesion of the air bubbles to the workpiece, the workpiece may be vibrated during the plating or may be subjected to bubbling to generate air bubbles by an inert gas or the like from below the workpiece.
  • the aforementioned various conditions in the plating step such as the concentration of the components of the plating solution, the bath temperature of the plating solution, and the current density applied to the workpiece are not always necessarily maintained within the aforementioned ranges during the period from the very start of the plating step to the completion of the plating step in order to exert the effects thereof, it is preferable that almost the same conditions as those at the start of the plating be maintained over the entire period.
  • chromium plating with the same thickness as in flat portions is applied also to portions that conventionally tend to have different plating thickness from the flat portions, such as corner portions and fine uneven portions of the workpiece, and the same covering power and throwing power as in hexavalent chromium plating are exerted even in trivalent chromium plating.
  • the plating thickness of the plated product produced in this embodiment can be appropriately set corresponding to the application or the like of the plated product, but portions with trivalent chromium plating alone, excluding base plating, preferably have a plating thickness of 5 ⁇ m or more and 600 ⁇ m or less, in order to exert the effects of the present invention more significantly.
  • the plating thickness is more preferably 50 ⁇ m or more, particularly preferably 100 ⁇ m or more.
  • the plating thickness may be measured, for example, using a fluorescent x-ray film thickness meter or the like, as needed.
  • the measurement using the fluorescent x-ray film thickness meter is difficult when the plating thickness is 50 ⁇ m or more, and therefore the cross sections of the plated product may be observed using a scanning electron microscope (SEM) in such a case.
  • SEM scanning electron microscope
  • the plating thickness can be determined by measuring the plating thickness of the plated product at several sites selected at random and arithmetically averaging the measurement results excluding abnormal values.
  • FIG. 1 shows the relationship between current density and plating thickness in hexavalent chromium plating and trivalent chromium plating disclosed in general literatures or the like. It is understood from this graph that it is difficult to exert throwing power in conventional trivalent chromium plating since the slope of the straight line that shows the relationship between current density and plating thickness rapidly increases at a current density of about 5 A/dm 2 . Further, it is understood from this graph that it is difficult to perform plating at a current density of 5 A/dm 2 or less and to perform plating with excellent covering power in conventional trivalent chromium plating.
  • the relationship between current density and plating thickness is as shown in FIG. 2 , where trivalent chromium plating at a low current density of 5 A/dm 2 or less is made possible as in hexavalent chromium plating.
  • the relationship between current density and plating thickness is made linear from the region at a low current density of 5 A/dm 2 or less to the region at a high current density of about 30 A/dm 2 , and thus plating can be performed with excellent throwing power. Accordingly, it can be seen also from this graph that the present invention provides a plating solution for trivalent chromium plating that is excellent in covering power and throwing power. The results of the study on this point will be described in detail below.
  • a plating solution was prepared so as to contain the ingredients shown in Table 1. That is, a plating solution containing chromium sulfate and having a concentration of Cr 3 ions of 1 mol/L was prepared. Formic acid and urea were added to the plating solution so that each has a concentration of 0.5 mol/L. Further, the plating solution was adjusted to have a pH of 1.5.
  • a Hull cell test was conducted with a current value of 5 A. The test was performed on three patterns at a bath temperature of 30° C., 35° C., and 40° C., and the test was conducted for 10 minutes. The results are shown in FIG. 3 and Table 1 together.
  • the plating thickness of the sample after the test was measured using a fluorescent x-ray film thickness meter.
  • the results are shown in FIG. 4 . It was seen from the results shown in Table 1 and FIG. 4 that at least a certain plating thickness could be ensured when the current density was low due to the concentration of Cr 3+ ions being 1 mol/L or less. Further, it was proved from the results shown in Table 1 and FIG. 4 that the bath temperature of less than 40° C. was advantageous in order to perform trivalent chromium plating with excellent covering power.
  • a Hull cell test was conducted with a reduced concentration of the bath composition itself, in order to improve the covering power by suppressing decrease in the bath viscosity and crystallization of the bath liquid. Specifically, the Hull cell test was conducted at a bath temperature of 25° C.
  • the present invention can provide a plating solution for trivalent chromium plating with excellent covering power so as to enlarge the application range of environmentally friendly plated products.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electroplating And Plating Baths Therefor (AREA)
  • Electroplating Methods And Accessories (AREA)
US15/576,892 2017-02-08 2017-08-25 Plating solution and method for producing plated product Abandoned US20200040477A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP2017-021006 2017-02-08
JP2017021006A JP6547232B2 (ja) 2017-02-08 2017-02-08 めっき液ならびにめっき製品の製造方法
PCT/JP2017/030445 WO2018146841A1 (ja) 2017-02-08 2017-08-25 めっき液、及び、めっき製品の製造方法

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EP (1) EP3388558A1 (enrdf_load_stackoverflow)
JP (1) JP6547232B2 (enrdf_load_stackoverflow)
KR (1) KR20190115481A (enrdf_load_stackoverflow)
TW (1) TW201835387A (enrdf_load_stackoverflow)
WO (1) WO2018146841A1 (enrdf_load_stackoverflow)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117488300A (zh) * 2024-01-02 2024-02-02 仪征亚新科双环活塞环有限公司 一种具有硬质镀层的活塞环及其制备方法

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11542620B2 (en) * 2018-02-09 2023-01-03 Nippon Steel Corporation Steel sheet for containers and method for producing steel sheet for containers
JP6624400B1 (ja) * 2018-07-04 2019-12-25 株式会社大都技研 遊技台

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JP2000249340A (ja) 1999-02-25 2000-09-12 Ngk Spark Plug Co Ltd グロープラグ及びその製造方法
JP2011099126A (ja) * 2008-01-24 2011-05-19 Okuno Chemical Industries Co Ltd ３価クロムめっき浴
JP6373185B2 (ja) * 2014-12-15 2018-08-15 株式会社Ｊｃｕ ３価クロムめっき液および３価クロムめっき方法

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117488300A (zh) * 2024-01-02 2024-02-02 仪征亚新科双环活塞环有限公司 一种具有硬质镀层的活塞环及其制备方法
US12345336B1 (en) 2024-01-02 2025-07-01 Asimco Shuanghuan Piston Ring (Yizheng) Co., Ltd. Piston ring with hard plating, and preparation method therefor

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WO2018146841A1 (ja) 2018-08-16
KR20190115481A (ko) 2019-10-14
JP2018127667A (ja) 2018-08-16
JP6547232B2 (ja) 2019-07-24
TW201835387A (zh) 2018-10-01
EP3388558A1 (en) 2018-10-17

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