CN111793815A - Method for passivating the surface of a blackplate or tinplate and electrolysis system for carrying out the method - Google Patents
Method for passivating the surface of a blackplate or tinplate and electrolysis system for carrying out the method Download PDFInfo
- Publication number
- CN111793815A CN111793815A CN202010270978.5A CN202010270978A CN111793815A CN 111793815 A CN111793815 A CN 111793815A CN 202010270978 A CN202010270978 A CN 202010270978A CN 111793815 A CN111793815 A CN 111793815A
- Authority
- CN
- China
- Prior art keywords
- chromium
- electrolytic
- passivation layer
- electrolytic solution
- oxide
- 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.)
- Pending
Links
- 238000000034 method Methods 0.000 title claims abstract description 53
- 238000005868 electrolysis reaction Methods 0.000 title claims description 39
- 239000005028 tinplate Substances 0.000 title claims description 8
- 239000008151 electrolyte solution Substances 0.000 claims abstract description 76
- 238000002161 passivation Methods 0.000 claims abstract description 72
- 229910000423 chromium oxide Inorganic materials 0.000 claims abstract description 59
- 239000011651 chromium Substances 0.000 claims abstract description 58
- WGLPBDUCMAPZCE-UHFFFAOYSA-N Trioxochromium Chemical compound O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 claims abstract description 57
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 51
- 239000010959 steel Substances 0.000 claims abstract description 51
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims abstract description 43
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 41
- 150000001845 chromium compounds Chemical class 0.000 claims abstract description 24
- 238000000151 deposition Methods 0.000 claims abstract description 20
- 239000002253 acid Substances 0.000 claims abstract description 19
- 150000003839 salts Chemical class 0.000 claims abstract description 17
- 239000008139 complexing agent Substances 0.000 claims abstract description 15
- 239000000872 buffer Substances 0.000 claims abstract description 7
- 238000000576 coating method Methods 0.000 claims description 48
- 239000011248 coating agent Substances 0.000 claims description 36
- JOPOVCBBYLSVDA-UHFFFAOYSA-N chromium(6+) Chemical compound [Cr+6] JOPOVCBBYLSVDA-UHFFFAOYSA-N 0.000 claims description 22
- VQWFNAGFNGABOH-UHFFFAOYSA-K chromium(iii) hydroxide Chemical compound [OH-].[OH-].[OH-].[Cr+3] VQWFNAGFNGABOH-UHFFFAOYSA-K 0.000 claims description 22
- 239000002585 base Substances 0.000 claims description 18
- 238000007254 oxidation reaction Methods 0.000 claims description 16
- 230000008021 deposition Effects 0.000 claims description 15
- 230000003647 oxidation Effects 0.000 claims description 15
- 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 13
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 claims description 12
- BFGKITSFLPAWGI-UHFFFAOYSA-N chromium(3+) Chemical compound [Cr+3] BFGKITSFLPAWGI-UHFFFAOYSA-N 0.000 claims description 10
- 239000000203 mixture Substances 0.000 claims description 10
- 229910000356 chromium(III) sulfate Inorganic materials 0.000 claims description 7
- 239000011696 chromium(III) sulphate Substances 0.000 claims description 7
- 235000015217 chromium(III) sulphate Nutrition 0.000 claims description 7
- 229910001220 stainless steel Inorganic materials 0.000 claims description 7
- 239000010935 stainless steel Substances 0.000 claims description 7
- 229910044991 metal oxide Inorganic materials 0.000 claims description 5
- 150000004706 metal oxides Chemical class 0.000 claims description 5
- 229910003455 mixed metal oxide Inorganic materials 0.000 claims description 5
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 claims description 4
- PHFQLYPOURZARY-UHFFFAOYSA-N chromium trinitrate Chemical compound [Cr+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O PHFQLYPOURZARY-UHFFFAOYSA-N 0.000 claims description 4
- XVHFYNOGAFYRJV-UHFFFAOYSA-L chromium(ii) oxalate Chemical compound [Cr+2].[O-]C(=O)C([O-])=O XVHFYNOGAFYRJV-UHFFFAOYSA-L 0.000 claims description 4
- HTXDPTMKBJXEOW-UHFFFAOYSA-N dioxoiridium Chemical compound O=[Ir]=O HTXDPTMKBJXEOW-UHFFFAOYSA-N 0.000 claims description 4
- 229910000457 iridium oxide Inorganic materials 0.000 claims description 4
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 4
- 229910052938 sodium sulfate Inorganic materials 0.000 claims description 4
- 235000011152 sodium sulphate Nutrition 0.000 claims description 4
- 229910052936 alkali metal sulfate Inorganic materials 0.000 claims description 3
- 239000012535 impurity Substances 0.000 claims description 3
- 239000000463 material Substances 0.000 claims description 3
- OTYBMLCTZGSZBG-UHFFFAOYSA-L potassium sulfate Chemical compound [K+].[K+].[O-]S([O-])(=O)=O OTYBMLCTZGSZBG-UHFFFAOYSA-L 0.000 claims description 3
- 229910052939 potassium sulfate Inorganic materials 0.000 claims description 3
- 235000011151 potassium sulphates Nutrition 0.000 claims description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 3
- BPNRRQFZIBQRMK-UHFFFAOYSA-N [O-2].[Ta+5].[Ir+3].[O-2].[O-2].[O-2] Chemical compound [O-2].[Ta+5].[Ir+3].[O-2].[O-2].[O-2] BPNRRQFZIBQRMK-UHFFFAOYSA-N 0.000 claims description 2
- WYYQVWLEPYFFLP-UHFFFAOYSA-K chromium(3+);triacetate Chemical compound [Cr+3].CC([O-])=O.CC([O-])=O.CC([O-])=O WYYQVWLEPYFFLP-UHFFFAOYSA-K 0.000 claims description 2
- QOWZHEWZFLTYQP-UHFFFAOYSA-K chromium(3+);triformate Chemical compound [Cr+3].[O-]C=O.[O-]C=O.[O-]C=O QOWZHEWZFLTYQP-UHFFFAOYSA-K 0.000 claims description 2
- 229910052697 platinum Inorganic materials 0.000 claims description 2
- 239000000243 solution Substances 0.000 claims description 2
- 239000006172 buffering agent Substances 0.000 claims 1
- 238000010668 complexation reaction Methods 0.000 claims 1
- 238000002360 preparation method Methods 0.000 claims 1
- 239000010410 layer Substances 0.000 description 103
- 239000004922 lacquer Substances 0.000 description 12
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 11
- 229910052760 oxygen Inorganic materials 0.000 description 11
- 239000001301 oxygen Substances 0.000 description 11
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 10
- 230000008569 process Effects 0.000 description 10
- 239000003792 electrolyte Substances 0.000 description 8
- 239000000126 substance Substances 0.000 description 8
- 238000005260 corrosion Methods 0.000 description 7
- 230000007797 corrosion Effects 0.000 description 7
- 238000009434 installation Methods 0.000 description 7
- 229920001169 thermoplastic Polymers 0.000 description 7
- QDOXWKRWXJOMAK-UHFFFAOYSA-N dichromium trioxide Chemical compound O=[Cr]O[Cr]=O QDOXWKRWXJOMAK-UHFFFAOYSA-N 0.000 description 5
- 238000004806 packaging method and process Methods 0.000 description 5
- 229920000642 polymer Polymers 0.000 description 5
- 239000004416 thermosoftening plastic Substances 0.000 description 5
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 4
- UOUJSJZBMCDAEU-UHFFFAOYSA-N chromium(3+);oxygen(2-) Chemical group [O-2].[O-2].[O-2].[Cr+3].[Cr+3] UOUJSJZBMCDAEU-UHFFFAOYSA-N 0.000 description 4
- 150000001875 compounds Chemical class 0.000 description 4
- 229920006254 polymer film Polymers 0.000 description 4
- 238000001228 spectrum Methods 0.000 description 4
- 239000005029 tin-free steel Substances 0.000 description 4
- 239000004280 Sodium formate Substances 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 3
- 239000010405 anode material Substances 0.000 description 3
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 description 3
- 239000004327 boric acid Substances 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
- 238000009713 electroplating Methods 0.000 description 3
- 150000004675 formic acid derivatives Chemical class 0.000 description 3
- 239000013067 intermediate product Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- HLBBKKJFGFRGMU-UHFFFAOYSA-M sodium formate Chemical compound [Na+].[O-]C=O HLBBKKJFGFRGMU-UHFFFAOYSA-M 0.000 description 3
- 235000019254 sodium formate Nutrition 0.000 description 3
- 239000000758 substrate Substances 0.000 description 3
- BDAGIHXWWSANSR-UHFFFAOYSA-M Formate Chemical compound [O-]C=O BDAGIHXWWSANSR-UHFFFAOYSA-M 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 229910001037 White iron Inorganic materials 0.000 description 2
- GVEHJMMRQRRJPM-UHFFFAOYSA-N chromium(2+);methanidylidynechromium Chemical compound [Cr+2].[Cr]#[C-].[Cr]#[C-] GVEHJMMRQRRJPM-UHFFFAOYSA-N 0.000 description 2
- 239000011247 coating layer Substances 0.000 description 2
- MIMDHDXOBDPUQW-UHFFFAOYSA-N dioctyl decanedioate Chemical compound CCCCCCCCOC(=O)CCCCCCCCC(=O)OCCCCCCCC MIMDHDXOBDPUQW-UHFFFAOYSA-N 0.000 description 2
- 239000011368 organic material Substances 0.000 description 2
- 238000010422 painting Methods 0.000 description 2
- 239000002985 plastic film Substances 0.000 description 2
- 229920006255 plastic film Polymers 0.000 description 2
- WFIZEGIEIOHZCP-UHFFFAOYSA-M potassium formate Chemical compound [K+].[O-]C=O WFIZEGIEIOHZCP-UHFFFAOYSA-M 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 229910003470 tongbaite Inorganic materials 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- LSNNMFCWUKXFEE-UHFFFAOYSA-N Sulfurous acid Chemical compound OS(O)=O LSNNMFCWUKXFEE-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- PUFIZHPPRJVXJC-UHFFFAOYSA-N [O-2].[Ta+5].[Ir+]=O.[O-2].[O-2] Chemical compound [O-2].[Ta+5].[Ir+]=O.[O-2].[O-2] PUFIZHPPRJVXJC-UHFFFAOYSA-N 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 238000001636 atomic emission spectroscopy Methods 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 150000003841 chloride salts Chemical class 0.000 description 1
- 230000000536 complexating effect Effects 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004070 electrodeposition Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- 150000004820 halides Chemical class 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 229910052741 iridium Inorganic materials 0.000 description 1
- GKOZUEZYRPOHIO-UHFFFAOYSA-N iridium atom Chemical compound [Ir] GKOZUEZYRPOHIO-UHFFFAOYSA-N 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 238000010030 laminating Methods 0.000 description 1
- 238000003475 lamination Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 1
- 229910052753 mercury Inorganic materials 0.000 description 1
- FXNGWBDIVIGISM-UHFFFAOYSA-N methylidynechromium Chemical compound [Cr]#[C] FXNGWBDIVIGISM-UHFFFAOYSA-N 0.000 description 1
- BPUBBGLMJRNUCC-UHFFFAOYSA-N oxygen(2-);tantalum(5+) Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Ta+5].[Ta+5] BPUBBGLMJRNUCC-UHFFFAOYSA-N 0.000 description 1
- 238000010979 pH adjustment Methods 0.000 description 1
- 238000005375 photometry Methods 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 239000002861 polymer material Substances 0.000 description 1
- 238000009420 retrofitting Methods 0.000 description 1
- 238000004611 spectroscopical analysis Methods 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 238000010301 surface-oxidation reaction Methods 0.000 description 1
- 229910001936 tantalum oxide Inorganic materials 0.000 description 1
- 150000004764 thiosulfuric acid derivatives Chemical class 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 238000011282 treatment Methods 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D9/00—Electrolytic coating other than with metals
- C25D9/04—Electrolytic coating other than with metals with inorganic materials
- C25D9/08—Electrolytic coating other than with metals with inorganic materials by cathodic processes
- C25D9/10—Electrolytic coating other than with metals with inorganic materials by cathodic processes on iron or steel
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
- C25D11/38—Chromatising
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
- C25D11/005—Apparatus specially adapted for electrolytic conversion coating
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D17/00—Constructional parts, or assemblies thereof, of cells for electrolytic coating
- C25D17/10—Electrodes, e.g. composition, counter electrode
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D21/00—Processes for servicing or operating cells for electrolytic coating
- C25D21/12—Process control or regulation
-
- 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
- C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
- C25D5/08—Electroplating with moving electrolyte e.g. jet electroplating
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D7/00—Electroplating characterised by the article coated
- C25D7/06—Wires; Strips; Foils
- C25D7/0614—Strips or foils
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D7/00—Electroplating characterised by the article coated
- C25D7/06—Wires; Strips; Foils
- C25D7/0614—Strips or foils
- C25D7/0628—In vertical cells
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D7/00—Electroplating characterised by the article coated
- C25D7/06—Wires; Strips; Foils
- C25D7/0614—Strips or foils
- C25D7/0642—Anodes
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D9/00—Electrolytic coating other than with metals
- C25D9/04—Electrolytic coating other than with metals with inorganic materials
- C25D9/08—Electrolytic coating other than with metals with inorganic materials by cathodic processes
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Automation & Control Theory (AREA)
- Electroplating And Plating Baths Therefor (AREA)
- Electroplating Methods And Accessories (AREA)
- Other Surface Treatments For Metallic Materials (AREA)
Abstract
The invention relates to a method for passivating the surface of a black or tin-plated steel sheet and an electrolytic system for carrying out the method. In a method for passivating the surface of a black or tin-plated steel sheet by electrolytically depositing a passivation layer containing chromium oxide on the surface, a passivation layer containing chromium is electrolytically deposited from an electrolytic solution (E) which contains a trivalent chromium compound and at least one salt for increasing the electrical conductivity and at least one acid or base for adjusting the desired pH value, wherein the electrolytic solution (E) is free of any further components, in particular free of organic complexing agents and free of buffers, in addition to the trivalent chromium compound and the at least one salt and the at least one acid or base.
Description
Technical Field
The invention relates to a method for passivating the surface of a blackplate or tinplate by electrolytically depositing a passivation layer containing chromium oxide on the surface, and to an electrolytic system for electrolytically depositing a passivation layer containing chromium and containing chromium oxide on the surface of a blackplate or tinplate.
Background
For the production of packaging, Steel sheets are known from the prior art which are electrolytically coated with a passivation layer consisting of chromium and chromium oxide/hydroxide, are referred to as Tin-Free Steel sheets ("Tin Free Steel", TFS) or as "electrolytically chromium plated Steel (ECCS)" and are alternatives to Tin-plated Steel sheets. Such tin-free steel sheets are distinguished in particular by good adhesion to lacquers or organic coatings (e.g. polymer coatings made of PP or PET). Despite the small thickness of the passivation layer consisting of chromium and chromium oxide/hydroxide (typically less than 20nm), such chromium-plated steel sheets have good corrosion resistance and good processability in the retrofitting methods for producing packaging, for example in deep-drawing and stretch-drawing processes.
Tin-plated steel sheets (tinplate) are usually provided with a passivation layer after electrolytic tin plating to inhibit oxidation of the tin surface with atmospheric oxygen. As a suitable passivation layer, a chromium-containing layer has proven to be advantageous, which can be electrolytically deposited on the tin surface of the tin-plated steel sheet from a chromium (VI) -containing electrolyte. The chromium-containing passivation layer is composed of metallic chromium and chromium oxide. Herein, "chromium oxide" is understood to mean all compounds of chromium and oxygen, including chromium hydroxides.
For the production of chromium-plated steel sheets (ECCS) and for passivating the surface of tin-plated steel sheets, electrolytic coating methods are known from the prior art, with which a passivation layer comprising metallic chromium and chromium oxide/chromium hydroxide can be applied to a strip-shaped substrate (uncoated steel sheet or tin-plated steel sheet) in a strip coating installation by using a chromium (VI) -containing electrolyte. However, due to the health and environmental hazard characteristics of chromium (VI) containing electrolytes used in electrolytic processes, this coating method has significant disadvantages and must be replaced by alternative coating methods in the foreseeable future, since the use of chromium (VI) containing materials is prohibited in the future.
For this reason, electrolytic coating methods have been developed in the prior art which can dispense with chromium (VI) -containing electrolytes. Thus, for example, WO2015/177314a1 and WO2015/177315a1 disclose a method for electrolytically passivating strip steel, in particular black or tin-plated steel, with a chromium metal-chromium oxide (Cr-CrOx) layer, in which method the steel plates are connected as cathodes in a strip coating installation and are guided through a single electrolytic solution at a high strip speed of more than 100m/min, which electrolytic solution contains a trivalent chromium compound (Cr (iii)) and complexing agents and conductivity-increasing salts and is free of chlorides and buffers, such as boric acid.
Here, organic substances, in particular formates, preferably sodium formate or potassium formate, are used as complexing agents. To adjust to a preferred pH value in the range of 2.5 to 3.5, the electrolytic solution can contain sulfuric acid. The deposition of the passivation layer consisting of chromium metal and chromium oxide can take place layer by layer in successive electrolytic cells or in successive coating installations, wherein the electrolytic cells are each filled with the same electrolytic solution.
It is observed here that the electrolytically deposited passivation layer can contain chromium sulfate and chromium carbide in addition to the metallic chromium and chromium oxide/hydroxide components, and the fraction of these components in the total coating weight of the passivation layer depends to a large extent on the current density set in the electrolytic cell. It has been found that three regions (region I, region II and region III) are formed as a function of the current density, wherein in a first region (region I) having a low current density below up to a first current density threshold no chromium-containing deposit is present on the steel substrate, in a second region (region II) having a medium current density the current density has a linear relationship with the coating weight of the deposited passivation layer, whereas in the case of a current density above a second current density threshold (region III) the applied passivation layer is partially decomposed such that the chromium coating weight of the passivation layer in this region first decreases with increasing current density and then reaches a constant value in the case of a higher current density. In this case, in the region with the medium current density (region II), predominantly up to 80% by weight (relative to the total weight of the passivation layer) of metallic chromium is deposited on the steel substrate, whereas above the second current density threshold value (region III), the passivation layer contains a higher chromium oxide fraction, which in the region of the higher current density amounts to between 1/4 and 1/3 of the total coating weight of the passivation layer. Here, the current density threshold value that defines the zones (zone I to zone III) with respect to each other is related to the belt speed at which the steel sheet moves through the electrolytic solution.
It has proven advantageous to include as high a proportion of chromium oxide as possible in the chromium-containing passivation layer in order to passivate the surface of the black or tin-plated steel sheet well against oxidation in oxygen-containing environments and to form a good adhesion base layer for organic coatings, such as lacquers or thermoplastics, in particular for the lamination of plastic films composed of PET, PP, PE or mixtures thereof.
Disclosure of Invention
It is therefore an object of the present invention to provide an electrolytic process which is as efficient as possible, cost-effective and environmentally and healthy, and which passivates the surface of black or tin-plated steel sheets with a passivation layer comprising chromium oxide/hydroxide based on an electrolytic solution with a trivalent chromium compound. In any case, the use of chromium (VI) -containing substances and also the use of chromium (VI) -containing substances as intermediate products in the electrolysis process should be avoided in order to be able to comply completely with the legal regulations for the prohibition of chromium (VI) -containing substances. Furthermore, the black or tin-plated steel sheets coated according to the method should have as high a resistance as possible to oxidation in oxygen-containing environments, in particular in atmospheric oxygen, and form a good adhesion base layer for organic coatings, for example for organic lacquers and polymer layers, in particular for polymer films, for example consisting of PET, PE or PP.
This object is achieved by an electrolysis method having the features of the first aspect of the invention and by an electrolysis system having the features of the second aspect of the invention and by a black or tin-plated steel sheet according to the third aspect of the invention. Preferred embodiments of the method and electrolysis system result from preferred embodiments of the invention.
In the method according to the invention, a passivation layer containing chromium oxide is electrolytically applied to an uncoated steel strip or a tin-plated steel strip (black iron belt) or tin-plated steel strip (white iron belt)) from an electrolytic solution, wherein the electrolytic solution contains a trivalent chromium compound and at least one salt for increasing the electrical conductivity and at least one acid or base for adjusting the desired pH value, wherein the electrolytic solution is free of any further components, in particular free of organic complexing agents and free of buffers, in addition to the trivalent chromium compound and the at least one salt and the at least one acid or base. Here, chromium (VI) -containing substances are not used, nor are chromium (VI) -containing substances used as intermediate products, so that the method is completely free of chromium (VI) -containing substances, and thus is environmentally friendly and health-friendly in performing the method.
It has been demonstrated in a surprising manner that even without the use of organic complexing agents (for example formates) as a constituent of the electrolytic solution, it is possible to electrolytically deposit a layer containing chromium oxide on the surface of a black or tin-plated steel sheet, wherein the layer deposited in the case of the use of an electrolytic solution without organic complexing agents consists at least substantially exclusively of chromium oxide.
Furthermore, it has been found that a layer of pure chromium oxide/chromium hydroxide, which forms the surface of the passivation layer, is advantageous with regard to oxidation resistance and the adhesion effect of organic coatings, such as lacquer or polymer layers. In the method according to the invention, it is therefore proposed to dispense with (organic) complexing agents, in particular formates, such as sodium formate or potassium formate, in the electrolytic solution. The passivation layer electrolytically deposited on the surface of the black or tin-plated steel sheet with this electrolyte consists at least substantially of pure chromium oxide and/or chromium hydroxide.
When referring to "chromium oxide" herein, all chromium oxide forms (CrOx) are meant, including chromium hydroxides, especially chromium (III) hydroxides and hydrated chromium (III) oxides and mixtures thereof. Preference is given here to the following compounds of chromium and oxygen, in which compounds chromium is present in trivalent form, in particular as chromium sesquioxide (Cr)2O3). Thus, the coating (in addition to the metallic chromium) preferably comprises only trivalent chromium compounds, in particular only trivalent chromium oxides and/or chromium hydroxides.
In this case, the proportion by weight of the chromium oxide (including the chromium hydroxide) of the electrolytically deposited passivation layer is preferably as high as possible. Preferably, the proportion by weight of chromium oxide and/or chromium hydroxide is greater than 90%, particularly preferably greater than 95%. This ensures, on the one hand, good passivation against surface oxidation of the black or tin-plated steel plate and, on the other hand, provides a good adhesion base layer with good adhesion to organic coatings, such as lacquers or polymer layers composed of thermoplastics, such as PET or PP.
For the electrolytic deposition of the passivation layer, the black or tin-plated steel strip connected as a cathode in the at least one electrolytic cell is brought into contact with the electrolytic solution during a predetermined electrolysis time. The electrolysis duration is preferably in the range from 0.3 to 5.0 seconds, particularly preferably between 0.6 and 1.5 seconds. For this purpose, the strip of black or tin-plated steel is guided through at least one electrolytic cell or through a plurality of electrolytic cells arranged one behind the other in the direction of belt travel at a predetermined belt speed, wherein the belt speed is preferably at least 100m/min, particularly preferably between 200m/min and 750 m/min. High efficiency of the method can be ensured by high belt speeds.
By means of the electrolysis duration and thus the belt speed, the thickness or coating weight of the passivation layer consisting of chromium oxide can be controlled. Preferably, the electrolysis duration is selected such that the deposited chromium oxide has at least 3mg/m2Preferably has a coating weight of 7mg/m2To 10mg/m2Coating weight of (c). In order to achieve sufficient oxidation and corrosion resistance for packaging applications, the chromium oxide coating weight in the passivation layer is preferably at least 5mg/m2More preferably greater than 7mg/m2. This coating weight of chromium oxide ensures sufficient resistance against oxidation and corrosion of the surface of the black or tin-plated steel sheet and also provides a good adhesion base for organic coatings such as lacquers or thermoplastic films.
Thus, in order to improve the corrosion resistance and to form a barrier for sulfur-containing materials, in particular for packaging fillers containing sulfate or sulfite, a coating layer, which consists of an organic material, in particular a lacquer or thermoplastic, in particular a polymer film consisting of PET, PE, PP or mixtures thereof, can be easily applied to the chromium oxide layer of the passivation layer, after the electrolytic application of the passivation layer, by painting the surface of the passivation layer with an organic lacquer or providing the plastic layer consisting of a thermoplastic, such as PET, PP and/or PE.
In order to ensure a method which is completely free of chromium (VI) species, a suitable anode is advantageously selected at the time of the electrolytic deposition of the passivation layer and arranged in the electrolytic cell, which anode inhibits the oxidation of chromium (III) in the trivalent chromium compound of the electrolytic solution to chromium (VI). For this purpose, anodes have proven suitable, in particular, with an outer surface or a passivation layer consisting of a metal oxide, in particular iridium oxide, or of a mixed metal oxide, in particular iridium-tantalum oxide. Preferably, the anode comprises neither stainless steel nor platinum. By using such an anode, it is possible to incorporate only trivalent chromium oxide and/or chromium hydroxide (especially Cr)2O3And/or Cr (OH)3) The coating of (2) is deposited on a black or tin-plated steel plate.
In electroplating chromium from a chromium (III) electrolyte, as in any electroplating process, there is at least one anodic oxidation present simultaneously in addition to the cathodic reduction. In the electroplating of chromium from a chromium (III) electrolyte, the anodic oxidation comprises, on the one hand, the oxidation of chromium (III) to chromium (VI) and, on the other hand, the oxidation of water to oxygen. These two potentials are close together in a standard electrode potential table:
(1) chromium (Cr)
(2) Oxygen (O)
The measurements in the associated denier Element (Daniell-Element) are used as the basis for the potential. The potential of the redox equation here depends on the anode material used. Thus, the choice of anode material definitively determines whether reaction (1) is inhibited and only reaction (2) occurs. In order to prevent the formation of Cr in the method according to the invention6+For suppressing the reaction (1), it is possible to use, for example, anodes based on metal oxides (in particular iridium oxide) or mixed metal oxides, for example mixed oxides consisting essentially of a multilayer formed from tantalum oxide and iridium oxideA metal oxide. Here, the anode can have an outer surface or an outer passivation layer composed of mixed metal oxides. In particular, anodes with a core made of titanium and an outer passivation layer made of tantalum oxide-iridium oxide have proved to be suitable. When using such an anode, the absence of chromium (VI) can be demonstrated by polarographic measurements (mercury drop electrodes).
When an anode made of stainless steel is used, oxidation of chromium (III) to chromium (VI) is not (sufficiently) suppressed (reaction 1). The reference measurement with the stainless steel anode already shows a clearly detectable chromium (VI) concentration after electrolysis durations of a few seconds. Therefore, the stainless steel as the anode material does not completely inhibit at least the oxidation of chromium (III) to chromium (VI). This leads to an enrichment of chromium (VI) in the chromium (III) electrolyte and thus to a different deposition mechanism. Therefore, anodes that do not contain stainless steel are preferably used in the process according to the invention. Thereby, it can be ensured that chromium (VI) is not produced as an intermediate product during electrolysis and that the deposited passivation layer contains only chromium (III) compounds or metallic chromium. Furthermore, post-treatments, for example with thiosulfates, which would otherwise be necessary when using stainless steel anodes, can thus be omitted in order to reduce the deposited chromium (VI) to chromium (III).
Preferably, the temperature of the electrolytic solution is in the range of 20 ℃ to 65 ℃, particularly preferably in the range of 30 ℃ to 55 ℃, in particular between 35 ℃ and 45 ℃. At these temperatures, the electrolytic deposition of the passivation layer containing chromium oxide is very efficient. When referring to the temperature of the electrolytic solution or the temperature in the electrolytic cell, respectively, reference is made to the average temperature, which is averaged over the total volume of the electrolytic cell. Typically, there is a temperature gradient in the cell with a temperature rise from top to bottom.
In addition to the trivalent chromium compound, the electrolytic solution comprises at least one salt that increases the conductivity and at least one acid or base for adjusting a suitable pH value, and is preferably free of chloride ions and free of buffers, in particular free of boric acid buffers.
Preferably, the trivalent chromium compound of the electrolytic solution is selected from the group consisting of: basic sulfuric acidChromium (III) (Cr)2(SO4)3) Chromium (III) nitrate (Cr (NO)3)3) Chromium (III) oxalate (CrC)2O4) Chromium (III) acetate (C)12H36ClCr3O22) Chromium (III) formate (Cr (OOCH)3) Or mixtures thereof. The concentration of the trivalent chromium compound in the electrolytic solution is preferably at least 10g/l, particularly preferably greater than 15g/l, in particular 20g/l or more.
In order to increase the conductivity, the electrolytic solution contains at least one salt, preferably an alkali metal sulfate, in particular potassium sulfate or sodium sulfate.
A very efficient deposition of the passivation layer comprising chromium oxide is achieved when the pH of the electrolytic solution (measured at a temperature of 20 ℃) is in the range of 2.3 to 5.0, preferably between 2.5 and 2.9. By adding an acid or a base to the electrolytic solution, a desired pH value can be adjusted. In the case of basic chromium (III) sulfate as trivalent chromium compound, sulfuric acid or a sulfuric acid-containing acid mixture is particularly suitable for adjusting the desired pH value.
A particularly advantageous composition of the electrolytic solution accordingly comprises basic chromium (III) sulfate (Cr) as trivalent chromium compound2(SO4)3) And sodium sulfate as conductivity-increasing salt, and sulfuric acid for adjusting the pH preferably in the range of 2.3 to 5.0.
Here, the electrolytic solution contains no other components except the trivalent chromium-containing substances, at least one salt for improving conductivity, and at least one acid or alkali for adjusting pH. This ensures a simple and low-cost production of the electrolytic solution.
To prepare the electrolytic solution, the trivalent chromium compound, from which organic residues are removed as far as possible, is first dissolved in water together with at least one salt and at least one acid or base for adjusting the desired pH value. Since the electrolytic solution does not contain a complexing agent, the solution thus obtained should be suitably left to stand (in atmospheric oxygen) for at least 5 days, preferably 7 days, for complexing. The desired pH can then be fine-adjusted by addition of an acid or base.
Can be produced with the method according to the inventionBlack or tin-plated steel sheet comprising a passivation layer of chromium oxide, wherein the passivation layer consists at least substantially exclusively of chromium oxide and/or chromium hydroxide, preferably exclusively of trivalent chromium oxide and/or chromium hydroxide, and preferably has a weight proportion of chromium oxide and/or chromium hydroxide of more than 90%, particularly preferably more than 95%. Such black or tin-plated steel sheets according to the invention are characterized by high corrosion resistance and good adhesion to organic coatings, such as lacquer or polymer layers. Preferably, the passivation layer comprises at least substantially only compounds of chromium and oxygen, chromium being present in trivalent form, in particular as Cr2O3And/or Cr (OH)3Are present.
In addition to chromium oxide and/or chromium hydroxide, a residual component of chromium sulfate (as an initial chromium compound of the electrodeposition process) can be contained in the passivation layer in addition to unavoidable impurities.
Preferably, the passivation layer consists of at least a first layer facing the surface of the blackened or tinplated steel sheet and a second layer forming the surface of the passivated blackened or tinplated steel sheet, wherein the first layer contains metallic chromium and the second layer consists of pure chromium oxide and/or chromium hydroxide, apart from the proposed chromium sulfate residual components and unavoidable impurities.
When the passivation layer has at least 3mg/m2Preferably 5mg/m2To 15mg/m2The total coating weight of chromium oxide and/or chromium hydroxide according to the invention enables particularly good corrosion resistance of the black or tin-plated steel sheet according to the invention to be achieved.
Drawings
The invention is explained in detail below with reference to embodiments according to which the invention is explained by way of example only and without limiting the scope of protection defined by the claims. The figures show:
FIG. 1 shows a schematic view of a strip coating installation for carrying out the method according to the invention;
fig. 2 shows a schematic cross-sectional view of a black or tin-coated steel strip which is coated in a method according to the invention using the strip coating installation of fig. 1;
figure 3 shows the GDOES spectrum of a layer deposited electrolytically on a steel strip by using an electrolytic solution, wherein the layer contains chromium metal, chromium oxide and chromium carbide, the electrolytic solution being composed of a trivalent chromium species (basic chromium (III) sulfate) and an organic complexing agent (sodium formate);
figure 4 shows the GDOES spectrum of a layer deposited electrolytically on a steel strip by using an electrolytic solution consisting essentially of pure chromium oxide, the electrolytic solution consisting of a trivalent chromium species (basic chromium (III) sulfate) without an organic complexing agent.
Detailed Description
Fig. 1 schematically shows a strip coating installation for carrying out the method according to the invention. The strip coating installation comprises three electrolysis cells 1a, 1b, 1c arranged next to one another or one after the other, which are each filled with an electrolytic solution E. An initially uncoated black steel strip or tin-plated steel strip (white iron belt) (hereinafter referred to as strip B) is guided successively through the electrolytic cells 1a to 1 c. In this connection, the belt B is pulled through the electrolytic cells 1a to 1c in the direction of belt travel v at a predetermined belt speed by means of a transport device, not shown here. Above the electrolytic cells 1a-1c are arranged current rollers S, by means of which the strip B is connected as cathode. Furthermore, a guide roller U is arranged in each electrolytic cell, around which the strip B is guided and is thereby diverted into or out of the respective electrolytic cell.
In each electrolytic cell 1a-1c, at least one anode pair AP is arranged, respectively, below the level of the electrolytic solution E. In the example shown, two anode pairs AP are provided in each cell 1a-1c, arranged one after the other in the direction of belt travel. In this case, the guide strip B passes between the opposing anodes of one anode pair AP. Thus, in the embodiment of fig. 1, two anode pairs AP are arranged in each electrolytic cell 1a, 1B, 1c such that the strip B is guided successively past these anode pairs AP. Here, the last anode pair APc in the downstream direction of the last electrolytic cell 1c viewed in the belt traveling direction v has a shortened length compared to the remaining anode pairs AP. This enables a higher current density to be generated with the last anode pair APc when the same high current is applied.
In order to prepare the electrolytic process, the strip B is first degreased, rinsed, pickled and rinsed again, and the strip B is guided in this pretreated form successively through the electrolytic cells 1a to 1c, wherein the strip B is connected as a cathode by feeding an electric current via current rollers S. The belt B is guided through the electrolytic cells 1a-1c at a belt speed of at least 100m/min and can be up to 900 m/min.
The electrolytic cells 1a to 1c arranged successively in the belt traveling direction are filled with the same electrolytic solution E, respectively. The electrolytic solution E contains a trivalent chromium compound, preferably basic chromium (III) sulfate, Cr2(SO4)3. To increase the conductivity, the electrolytic solution E also contains a salt, in particular an alkali metal sulfate, for example potassium sulfate or sodium sulfate, and an acid or a base for adjusting the appropriate pH value. The pH of the first electrolytic solution E is adjusted to a preferred value between 2.0 and 5.0 by adding an acid or a base. In the case of using basic chromium (III) sulfate as trivalent chromium compound, sulfuric acid, for example, has proven to be a suitable acid for pH adjustment. The concentration of the trivalent chromium compound in the electrolytic solution E is preferably at least 10g/l, particularly preferably 20g/l or more.
Suitably, in the electrolytic cells 1a, 1b, 1c, the temperature of the electrolytic solution E is as high, and preferably between 25 ℃ and 70 ℃. However, different temperatures of the electrolytic solution may be set in the electrolytic cells 1a, 1b, and 1 c. Therefore, for example, the electrolytic solution temperature in the intermediate electrolytic tank 1b can be lower than the electrolytic solution temperature in the front electrolytic tank 1a disposed upstream. The temperature of the electrolytic solution in the intermediate cell 1b is here, for example, between 25 ℃ and 37 ℃, in particular 35 ℃, while the temperature of the electrolytic solution E in the preceding cell 1a is between 40 ℃ and 75 ℃, in particular 55 ℃.
The electrolytic solution E contains no organic components, in particular no complexing agents. The electrolytic solution E is free of halides and buffers such as boric acid.
The anode pairs AP arranged in the electrolysis cells 1a to 1c are subjected to a direct current, so that a sufficiently high current density is present in each of the electrolysis cells 1a, 1b, 1c in order to produce the electrolytic deposition of a chromium-containing, in particular Cr (III) -containing, layer. The minimum current density required for this depends on the belt speed and is, for example, approximately 15 to 20A/dm in the case of a (minimum) belt speed of 100m/min2. As the belt speed increases, the minimum current density required for the electrolytic deposition of chromium-containing layers also increases.
Depending on the belt speed, the belt B, which is connected as a cathode and is guided through the electrolysis cells 1a to 1c, is brought into electrolytic contact with the electrolytic solution E in the electrolysis cells 1a, 1B, 1c, respectively, during the electrolysis duration t1, t2 or t 3. The duration of electrolysis t1, t2, t3 in each electrolytic cell 1a, 1b, 1c is between 0.5 and 2.0 seconds at a belt speed between 100 and 700 m/min. Preferably, the belt speed is adjusted in such a way that the electrolysis duration in each electrolytic cell 1a, 1b, 1c is less than 2 seconds, in particular between 0.6 and 1.8 seconds. The total electrolysis duration tG ═ t1+ t2+ t3 for the strip B to come into electrolytic contact with the electrolytic solution E through all the cells 1a to 1c is between 1.8 and 5.4 seconds, respectively. Here, the duration of electrolysis in the respective electrolysis cells 1a, 1b, 1c can be adjusted by the belt speed on the one hand, and by the size specification of the electrolysis cells 1a to 1c on the other hand.
When the current density in the respective cell 1a-1c is adjusted to be greater than the minimum current density, a layer is deposited in each cell 1a, 1B, 1c on at least one side of the strip B, which layer consists at least substantially of chromium oxide and/or chromium hydroxide and may contain chromium sulfate when using a sulfate-containing electrolytic solution E. In each case one layer B1, B2, B3 is produced in each electrolytic cell 1a, 1B, 1c, wherein the composition of the layers B1, B2, B3 is at least substantially identical when the same electrolytic solution E is contained in the electrolytic cells 1a to 1c and the same electrolysis parameters, in particular the same current density and temperature, are used.
The proportion by weight of chromium oxide/chromium hydroxide in the coating weight of the layers B1, B2 and B3 and, correspondingly, in the total coating weight of the coating composed of these layers B1, B2 and B3 is expediently at least 90%, preferably greater than 95%.
In fig. 2 a cross-sectional view of a strip B electrolytically coated by means of the method according to the invention is schematically shown. Here, a passivation layer P is applied on one side of the strip B, which passivation layer consists of the individual layers B1, B2, B3. Here, each individual layer B1, B2, B3 is applied to the surface in one of the electrolysis cells 1a, 1B, 1 c.
The layer structure of the layers B1, B2, B3 deposited on the tape can be verified by GDOES Spectroscopy (glowscharge Optical Emission Spectroscopy).
It can be shown by reference tests that, when using electrolytic solutions not according to the invention, known from the prior art, with organic complexing agents, such as formate, a metallic chromium layer with a thickness of 10 to 15nm is deposited on the strip B in the electrolytic cells 1a, 1B, 1c depending on the duration of electrolysis. The surfaces of these layers are oxidized after deposition and are predominantly Cr2O3Chromium oxide in the form of Cr2O2(OH)2The mixed oxide-hydroxide in the form of a salt is present. These oxide layers are several nanometers thick. In addition, by building up the entire layer uniformly, chromium-carbon and chromium sulfate compounds are formed, which are formed by reduction of an organic complexing agent or sulfate of an electrolytic solution. Typical GDOES spectra of the layers B1, B2, B3 deposited in the respective cells show a significant increase in the oxygen signal in the first nanometer of the layer, from which it can be concluded that the oxide layer is concentrated at the surface of the respective layer (fig. 3).
In fig. 4, the GDOES spectrum of band B is shown, band B being passivated with the method according to the invention by using an electrolytic solution E, wherein electrolytic solution E does not contain an organic complexing agent, such as formate. It is shown here that a layer (passivation layer) is deposited on the strip B, which layer consists at least substantially only of chromium oxide/hydroxide and may also contain a small proportion of chromium sulfate.
The composition of the passivation layer can be reacted at 90 ℃ for 10 minutes with 10ml 6% H according to European Standard DIN EN 10202 (chromia photometry: (European Standard) step 1: 40ml NaOH (330g/L)2O2Oxidation, photometry @370 nm).
After the electrolytic deposition of the passivation layer, the strip B provided with the passivation layer is rinsed, dried and oiled, for example with DOS (dioctyl sebacate). Then, electrolyzing the belt B coated with the passivation layer can additionally provide an organic coating layer. In this case, an organic coating is applied in a known manner, for example by painting or laminating a plastic film, to the surface of the passivation layer, i.e. to the upper layer B3 made of chromium oxide. The chromium oxide surface of layer B3 provides a good adhesion base for the organic material of the coating. The organic coating can be, for example, an organic lacquer or a polymer film composed of a thermoplastic polymer (for example PET, PE, PP or mixtures thereof). The organic Coating can be applied, for example, in a "Coil-Coating" process or in a flat-plate process, in which the coated strip is first divided into plates, which are subsequently lacquered with an organic lacquer or coated with a polymer film.
In order to achieve sufficient oxidation and corrosion resistance for packaging applications, the passivation layer applied with the method according to the invention preferably has at least 3mg/m2Preferably at least 5mg/m2Of chromium oxide/chromium hydroxide. Up to about 15mg/m in the coating weight of chromium oxide/chromium hydroxide2In this case, good adhesion of the organic lacquer or the thermoplastic polymer material on the surface of the passivation layer B can be achieved. Therefore, the preferred range of the coating weight of chromium oxide/chromium hydroxide in the passivation layer is 3mg/m2And 15mg/m2In between, particularly preferably 5mg/m2And 15mg/m2In the meantime.
In the illustrated embodiment of the method according to the invention, the thickness or coating weight of the individual layers B1, B2, B3 can be adjusted by means of the electrolysis times t1, t2, t3 and the current density in the electrolysis cell. As long as a sufficiently high current density is selected in the electrolytic cell, the thickness or coating weight of the deposited layers B1, B2, B3 is linearly dependent on the current density and (with constant temperature of the electrolytic solution) on the electrolysis times t1, t2, t3 in the electrolytic cell, during which time strip B is brought into electrolytic contact with electrolytic solution E.
The coating weight of the passivation layer can thus be adjusted by the duration of the electrolysis and/or the current density of the electrolytic contact of the strip B with the electrolytic solution E. The electrolysis duration t depends in turn on the size specification of the electrolysis cell and the belt speed.
Claims (20)
1. Method for passivating the surface of a black or tin-plated steel sheet by electrolytically depositing a passivation layer containing chromium oxide on the surface, wherein the passivation layer containing chromium is electrolytically deposited from an electrolytic solution (E) which comprises a trivalent chromium compound and at least one salt for increasing the electrical conductivity and at least one acid or base for adjusting the desired pH value, characterized in that the electrolytic solution (E) is free of any further components apart from the trivalent chromium compound and the at least one salt and the at least one acid or base and is free of organic complexing agents and free of buffering agents.
2. The method of claim 1, wherein the passivation layer consists at least substantially of chromium oxide and/or chromium hydroxide.
3. The method according to claim 1, characterized in that the passivation layer has a weight fraction of chromium oxide and/or chromium hydroxide of more than 90%.
4. Method according to claim 1, characterized in that for the electrolytic deposition of the passivation layer, the black or tin-plated steel plate is connected as a cathode and is in contact with the electrolytic solution (E) during an electrolysis duration, wherein the electrolysis duration is in the range of 0.1 to 2.0 seconds, and preferably between 1.0 and 1.5 seconds.
5. Method according to any of the preceding claims, characterized in that for the electrolytic deposition of the passivation layer the black or tin-plated steel sheet is guided past at least one electrolytic cell (1) or a plurality of electrolytic cells (1a, 1b, 1c) arranged one after the other in the direction of belt travel at a preset belt speed (v), wherein the belt speed (v) is at least 100 m/min.
6. The method according to claim 5, characterized in that the temperature of the electrolytic solution (E) has an average temperature in relation to the volume of the respective electrolytic cell (1; 1a, 1b, 1c) which is in the range of 20 ℃ to 65 ℃, preferably in the range of 30 ℃ to 55 ℃, particularly preferably between 35 ℃ and 45 ℃.
7. The method according to claim 5 or 6, characterized in that in each of the electrolytic cells (1, 1a-1c) the electrolysis duration (t) of the black or tin-plated steel sheet in electrolytic contact with the electrolytic solution (E) is less than 1.0 second, wherein the total electrolysis duration (t) of the black or tin-plated steel sheet in electrolytic contact with the electrolytic solution (E) in all of the electrolytic cells (1, 1a-1c) isG) Between 0.5 and 2.0 seconds, in particular between 1.0 and 1.8 seconds.
8. The method according to any of the preceding claims, wherein the trivalent chromium compound is selected from the group consisting of: basic chromium (III) sulfate (Cr)2(SO4)3) Chromium (III) nitrate (Cr (NO)3)3) Chromium (III) oxalate (CrC)2O4) Chromium (III) acetate (C)12H36ClCr3O22) Chromium (III) formate (Cr (OOCH)3) Or a mixture thereof, and the salt of the electrolytic solution (E) comprises at least one alkali metal sulfate, in particular potassium sulfate or sodium sulfate.
9. The method according to any of the preceding claims, characterized in that the electrolytic solution has a pH value (measured at a temperature of 20 ℃) in the range of 2.3 to 5.0, preferably between 2.5 and 2.9, wherein the pH value is adjusted by adding at least one acid to the electrolytic solution.
10. A method according to any of the preceding claims, characterized in that the concentration of the trivalent chromium compound in the electrolytic solution is at least 10 g/l.
11. Method according to any of the preceding claims, characterized in that the total coating weight of the chromium oxide and/or chromium hydroxide of the passivation layer applied from the electrolytic solution is at least 3mg/m2。
12. The method according to any of the preceding claims, characterized in that the oxidation of chromium (III) in the trivalent chromium compound of the electrolytic solution (E) to chromium (VI) is inhibited by using a suitable anode in the electrolytic deposition of the passivation layer.
13. The method of claim 12, wherein the anode is free of stainless steel and platinum.
14. The method according to claim 12, characterized in that the anode comprises an outer surface or coating consisting of a metal oxide, in particular iridium oxide, or of a mixed metal oxide, or of one of said materials.
15. The method according to any one of the preceding claims, wherein, for the preparation of the electrolytic solution, the trivalent chromium compound, the at least one salt and the at least one acid or base for adjusting the desired pH value, which are free of organic residues except unavoidable impurities, are dissolved in water, the solution thus obtained is left for complexation for at least 5 days, preferably 7 days, and the fine adjustment of the pH value is subsequently achieved by adding acid or base.
16. An electrolytic system for electrolytically passivating a surface of a black or tin-plated steel sheet by depositing a passivation layer containing chromium oxide on the surface, wherein the electrolytic system comprises:
at least one electrolytic cell (1) filled with an electrolytic solution (E), or a plurality of electrolytic cells (1a, 1b, 1c) arranged one after the other, each filled with the same electrolytic solution (E), wherein the electrolytic solution (E) has no further components, in particular no organic components and no buffers, apart from the trivalent chromium compound and at least one salt for increasing the electrical conductivity and at least one acid or base for adjusting the desired pH value,
for the electrolytic deposition of the passivation layer, the black or tin-plated steel sheet is guided in the direction of belt travel at a predetermined belt speed (v) through the at least one electrolytic cell (1) or through the plurality of electrolytic cells (1a, 1b, 1c) one after the other, whereby the surface is brought into electrolytic contact with the electrolytic solution (E) and the passivation layer, which consists at least substantially only of chromium oxide and/or chromium hydroxide, is deposited on the surface.
17. The electrolysis system according to claim 15, wherein in the or each electrolysis cell (1; 1a, 1b, 1c) an anode (2) is arranged having an outer surface or coating consisting of a metal oxide, in particular iridium oxide, or of a mixed metal oxide, in particular iridium-tantalum oxide.
18. A black or tin-plated steel sheet having a surface which has been passivated by electrolytic deposition of a passivation layer containing chromium oxide, characterized in that the passivation layer consists at least substantially exclusively of chromium oxide and/or chromium hydroxide and has a proportion by weight of chromium oxide and/or chromium hydroxide of more than 90%.
19. A blackplate or tinplate according to claim 17, wherein the passivation layer consists of at least a first layer facing the surface of the blackplate or tinplate and a second layer forming the passivated surface of the blackplate or tinplate, wherein the first layer comprises metallic chromium and the second layer consists of pure chromium oxide and/or chromium hydroxide.
20. A black or tin-plated steel sheet according to claim 17 or 18, wherein the passivation layer has a total coating weight of chromium oxide and/or hydroxide of at least 3mg/m2。
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE102019109354.6A DE102019109354A1 (en) | 2019-04-09 | 2019-04-09 | Process for passivating the surface of a black plate or a tin plate and an electrolysis system for carrying out the process |
| DE102019109354.6 | 2019-04-09 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN111793815A true CN111793815A (en) | 2020-10-20 |
Family
ID=69571915
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010270978.5A Pending CN111793815A (en) | 2019-04-09 | 2020-04-08 | Method for passivating the surface of a blackplate or tinplate and electrolysis system for carrying out the method |
Country Status (8)
| Country | Link |
|---|---|
| US (1) | US20200325591A1 (en) |
| EP (1) | EP3722464A1 (en) |
| JP (1) | JP6989646B2 (en) |
| KR (1) | KR20200119194A (en) |
| CN (1) | CN111793815A (en) |
| BR (1) | BR102020004546A2 (en) |
| CA (1) | CA3075010C (en) |
| DE (1) | DE102019109354A1 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20210129127A (en) * | 2019-02-25 | 2021-10-27 | 타타 스틸 이즈무이덴 베.뷔. | How to make chromium oxide coated tinplate |
| DE102021125696A1 (en) | 2021-10-04 | 2023-04-06 | Thyssenkrupp Rasselstein Gmbh | Process for passivating the surface of a tinplate and an electrolysis system for carrying out the process |
Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1318311A (en) * | 1969-07-09 | 1973-05-31 | Uss Eng & Consult | Can stock with differential protective coatings |
| US4414078A (en) * | 1979-08-09 | 1983-11-08 | Toyo Kohan Company, Limited | Method for pretreatment in the production of tin-free steel |
| US4421828A (en) * | 1979-09-06 | 1983-12-20 | Carnaud S.A. | Steel sheet carrying a protective layer and process for producing such a sheet |
| US6004448A (en) * | 1995-06-06 | 1999-12-21 | Atotech Usa, Inc. | Deposition of chromium oxides from a trivalent chromium solution containing a complexing agent for a buffer |
| US6099714A (en) * | 1996-08-30 | 2000-08-08 | Sanchem, Inc. | Passification of tin surfaces |
| CN104919091A (en) * | 2012-11-21 | 2015-09-16 | 塔塔钢铁艾默伊登有限责任公司 | Chromium-chromium oxide coatings applied to steel substrates for packaging applications and a method for producing said coatings |
| WO2015177315A1 (en) * | 2014-05-21 | 2015-11-26 | Tata Steel Ijmuiden B.V. | Method for manufacturing chromium-chromium oxide coated substrates and coated substrates produced thereby |
| CN105473767A (en) * | 2013-06-20 | 2016-04-06 | 塔塔钢铁艾默伊登有限责任公司 | Method for manufacturing chromium-chromium oxide coated substrates |
| CN106414806A (en) * | 2014-05-21 | 2017-02-15 | 塔塔钢铁艾默伊登有限责任公司 | Method for plating a moving metal strip and coated metal strip produced thereby |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2693444A (en) * | 1951-02-12 | 1954-11-02 | Battelle Development Corp | Electrodeposition of chromium and alloys thereof |
| JP2005060756A (en) * | 2003-08-08 | 2005-03-10 | Hitachi Cable Ltd | Rolled copper foil for fpc and method for treating copper foil |
| US7052592B2 (en) * | 2004-06-24 | 2006-05-30 | Gueguine Yedigarian | Chromium plating method |
| JP5299887B2 (en) * | 2008-03-26 | 2013-09-25 | 奥野製薬工業株式会社 | Electrolytic solution for trivalent chromium plating film |
| US8512541B2 (en) * | 2010-11-16 | 2013-08-20 | Trevor Pearson | Electrolytic dissolution of chromium from chromium electrodes |
| JPWO2015037391A1 (en) * | 2013-09-12 | 2017-03-02 | 奥野製薬工業株式会社 | Trivalent chromium plating bath |
| BR112019009702B1 (en) * | 2016-11-14 | 2023-03-28 | Tata Steel Ijmuiden B.V. | METHOD FOR ELECTROGALVANIZING A STEEL STRIP NOT COATED WITH A COATING LAYER |
| KR20210129127A (en) * | 2019-02-25 | 2021-10-27 | 타타 스틸 이즈무이덴 베.뷔. | How to make chromium oxide coated tinplate |
-
2019
- 2019-04-09 DE DE102019109354.6A patent/DE102019109354A1/en active Pending
-
2020
- 2020-02-12 EP EP20156810.2A patent/EP3722464A1/en active Pending
- 2020-03-06 BR BR102020004546-6A patent/BR102020004546A2/en not_active IP Right Cessation
- 2020-03-10 CA CA3075010A patent/CA3075010C/en active Active
- 2020-03-26 JP JP2020055306A patent/JP6989646B2/en active Active
- 2020-03-27 KR KR1020200037378A patent/KR20200119194A/en not_active Application Discontinuation
- 2020-04-06 US US16/840,858 patent/US20200325591A1/en not_active Abandoned
- 2020-04-08 CN CN202010270978.5A patent/CN111793815A/en active Pending
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1318311A (en) * | 1969-07-09 | 1973-05-31 | Uss Eng & Consult | Can stock with differential protective coatings |
| US4414078A (en) * | 1979-08-09 | 1983-11-08 | Toyo Kohan Company, Limited | Method for pretreatment in the production of tin-free steel |
| US4421828A (en) * | 1979-09-06 | 1983-12-20 | Carnaud S.A. | Steel sheet carrying a protective layer and process for producing such a sheet |
| US6004448A (en) * | 1995-06-06 | 1999-12-21 | Atotech Usa, Inc. | Deposition of chromium oxides from a trivalent chromium solution containing a complexing agent for a buffer |
| US6099714A (en) * | 1996-08-30 | 2000-08-08 | Sanchem, Inc. | Passification of tin surfaces |
| CN104919091A (en) * | 2012-11-21 | 2015-09-16 | 塔塔钢铁艾默伊登有限责任公司 | Chromium-chromium oxide coatings applied to steel substrates for packaging applications and a method for producing said coatings |
| CN105473767A (en) * | 2013-06-20 | 2016-04-06 | 塔塔钢铁艾默伊登有限责任公司 | Method for manufacturing chromium-chromium oxide coated substrates |
| WO2015177315A1 (en) * | 2014-05-21 | 2015-11-26 | Tata Steel Ijmuiden B.V. | Method for manufacturing chromium-chromium oxide coated substrates and coated substrates produced thereby |
| CN106414806A (en) * | 2014-05-21 | 2017-02-15 | 塔塔钢铁艾默伊登有限责任公司 | Method for plating a moving metal strip and coated metal strip produced thereby |
Also Published As
| Publication number | Publication date |
|---|---|
| CA3075010C (en) | 2022-05-17 |
| EP3722464A1 (en) | 2020-10-14 |
| CA3075010A1 (en) | 2020-10-09 |
| BR102020004546A2 (en) | 2020-10-20 |
| US20200325591A1 (en) | 2020-10-15 |
| JP6989646B2 (en) | 2022-01-05 |
| JP2020172701A (en) | 2020-10-22 |
| KR20200119194A (en) | 2020-10-19 |
| DE102019109354A1 (en) | 2020-10-15 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN111321431B (en) | Method for producing a coated metal strip | |
| CN111793815A (en) | Method for passivating the surface of a blackplate or tinplate and electrolysis system for carrying out the method | |
| JPH0430475B2 (en) | ||
| MX2010011889A (en) | Process for production of tin-plated steel sheets, tin-plated steel sheets and chemical conversion treatment fluid. | |
| CN111321432B (en) | Method for producing coated metal strip | |
| WO2012035763A1 (en) | Apparatus for continuous electrolytic treatment of steel sheet and method of producing surface-treated steal sheet using same | |
| CN111793809B (en) | Method for producing coated metal strips and electrolysis system for carrying out the method | |
| Yao et al. | Environmentally friendly chromium electrodeposition: effect of pre-electrolysis on a Cr (III) bath in an anion-exchange membrane reactor | |
| CN115279950A (en) | Method for passivating tin-plated steel strip and installation for producing said passivated tin-plated steel strip | |
| JP7554805B2 (en) | Method for passivating the surface of tinplate and electrolytic system for carrying out the method - Patents.com | |
| WO2016111349A1 (en) | Steel sheet for container and method for producing steel sheet for container | |
| JPH05222572A (en) | Electrogalvanized steel sheet having two plated layer and excellent in blackening resistance | |
| EP2309029A1 (en) | Process for producing tin-plated steel plate, and tin-plated steel plate | |
| JP5928991B2 (en) | Method for producing electrogalvanized steel sheet | |
| WO2016111350A1 (en) | Steel sheet for container and method for producing steel sheet for container |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| WD01 | Invention patent application deemed withdrawn after publication |
Application publication date: 20201020 |
|
| WD01 | Invention patent application deemed withdrawn after publication |