WO2002050341A2 - Process for the passivation of tinned stainless steel strip with a chrome-free passivation film - Google Patents
Process for the passivation of tinned stainless steel strip with a chrome-free passivation film Download PDFInfo
- Publication number
- WO2002050341A2 WO2002050341A2 PCT/IT2001/000643 IT0100643W WO0250341A2 WO 2002050341 A2 WO2002050341 A2 WO 2002050341A2 IT 0100643 W IT0100643 W IT 0100643W WO 0250341 A2 WO0250341 A2 WO 0250341A2
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- passivation
- chrome
- stainless steel
- tinned
- steel strip
- Prior art date
Links
- 238000002161 passivation Methods 0.000 title claims abstract description 67
- 238000000034 method Methods 0.000 title claims abstract description 42
- 229910001220 stainless steel Inorganic materials 0.000 title claims abstract description 23
- 239000010935 stainless steel Substances 0.000 title claims abstract description 23
- 238000007598 dipping method Methods 0.000 claims abstract description 4
- 239000003973 paint Substances 0.000 claims abstract description 4
- 239000010936 titanium Substances 0.000 claims abstract description 4
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims abstract description 3
- 239000010941 cobalt Substances 0.000 claims abstract description 3
- 229910017052 cobalt Inorganic materials 0.000 claims abstract description 3
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims abstract description 3
- 238000004519 manufacturing process Methods 0.000 claims abstract description 3
- 229910052750 molybdenum Inorganic materials 0.000 claims abstract description 3
- 239000011733 molybdenum Substances 0.000 claims abstract description 3
- 150000003839 salts Chemical class 0.000 claims abstract description 3
- 229910052723 transition metal Inorganic materials 0.000 claims abstract description 3
- 150000003624 transition metals Chemical class 0.000 claims abstract description 3
- VWDWKYIASSYTQR-UHFFFAOYSA-N sodium nitrate Chemical compound [Na+].[O-][N+]([O-])=O VWDWKYIASSYTQR-UHFFFAOYSA-N 0.000 claims description 19
- 239000007864 aqueous solution Substances 0.000 claims description 11
- 239000000203 mixture Substances 0.000 claims description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 10
- 229910020491 K2TiF6 Inorganic materials 0.000 claims description 7
- 239000011734 sodium Substances 0.000 claims description 5
- RXCBCUJUGULOGC-UHFFFAOYSA-H dipotassium;tetrafluorotitanium;difluoride Chemical compound [F-].[F-].[F-].[F-].[F-].[F-].[K+].[K+].[Ti+4] RXCBCUJUGULOGC-UHFFFAOYSA-H 0.000 claims description 4
- 235000010344 sodium nitrate Nutrition 0.000 claims description 4
- 239000004317 sodium nitrate Substances 0.000 claims description 4
- MEYVLGVRTYSQHI-UHFFFAOYSA-L cobalt(2+) sulfate heptahydrate Chemical compound O.O.O.O.O.O.O.[Co+2].[O-]S([O-])(=O)=O MEYVLGVRTYSQHI-UHFFFAOYSA-L 0.000 claims description 2
- BBJSDUUHGVDNKL-UHFFFAOYSA-J oxalate;titanium(4+) Chemical compound [Ti+4].[O-]C(=O)C([O-])=O.[O-]C(=O)C([O-])=O BBJSDUUHGVDNKL-UHFFFAOYSA-J 0.000 claims description 2
- 235000015393 sodium molybdate Nutrition 0.000 claims description 2
- 239000011684 sodium molybdate Substances 0.000 claims description 2
- TVXXNOYZHKPKGW-UHFFFAOYSA-N sodium molybdate (anhydrous) Chemical compound [Na+].[Na+].[O-][Mo]([O-])(=O)=O TVXXNOYZHKPKGW-UHFFFAOYSA-N 0.000 claims description 2
- ZXAUZSQITFJWPS-UHFFFAOYSA-J zirconium(4+);disulfate Chemical compound [Zr+4].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O ZXAUZSQITFJWPS-UHFFFAOYSA-J 0.000 claims description 2
- PMTRSEDNJGMXLN-UHFFFAOYSA-N titanium zirconium Chemical compound [Ti].[Zr] PMTRSEDNJGMXLN-UHFFFAOYSA-N 0.000 claims 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 abstract description 2
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 abstract description 2
- 229910052719 titanium Inorganic materials 0.000 abstract description 2
- 229910052726 zirconium Inorganic materials 0.000 abstract description 2
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 10
- 239000000243 solution Substances 0.000 description 9
- 230000010287 polarization Effects 0.000 description 8
- 238000011282 treatment Methods 0.000 description 6
- 239000003792 electrolyte Substances 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 4
- 238000005260 corrosion Methods 0.000 description 4
- 230000007797 corrosion Effects 0.000 description 4
- 238000004458 analytical method Methods 0.000 description 3
- 239000007979 citrate buffer Substances 0.000 description 3
- 230000007613 environmental effect Effects 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 238000004611 spectroscopical analysis Methods 0.000 description 3
- 239000003440 toxic substance Substances 0.000 description 3
- JHWIEAWILPSRMU-UHFFFAOYSA-N 2-methyl-3-pyrimidin-4-ylpropanoic acid Chemical compound OC(=O)C(C)CC1=CC=NC=N1 JHWIEAWILPSRMU-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- 238000004833 X-ray photoelectron spectroscopy Methods 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 231100000614 poison Toxicity 0.000 description 2
- 238000004626 scanning electron microscopy Methods 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 229910019142 PO4 Inorganic materials 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- 238000001479 atomic absorption spectroscopy Methods 0.000 description 1
- ZCDOYSPFYFSLEW-UHFFFAOYSA-N chromate(2-) Chemical compound [O-][Cr]([O-])(=O)=O ZCDOYSPFYFSLEW-UHFFFAOYSA-N 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- ZOMNIUBKTOKEHS-UHFFFAOYSA-L dimercury dichloride Chemical class Cl[Hg][Hg]Cl ZOMNIUBKTOKEHS-UHFFFAOYSA-L 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000009993 protective function Effects 0.000 description 1
- 239000011241 protective layer Substances 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 238000009991 scouring Methods 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
- 231100000167 toxic agent Toxicity 0.000 description 1
- 239000011800 void material Substances 0.000 description 1
- 239000003643 water by type Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
- C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
- C23C22/40—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing molybdates, tungstates or vanadates
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
- C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
- C23C22/34—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
- C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
- C23C22/46—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing oxalates
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
- C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
- C23C22/48—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 not containing phosphates, hexavalent chromium compounds, fluorides or complex fluorides, molybdates, tungstates, vanadates or oxalates
- C23C22/58—Treatment of other metallic material
-
- 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
-
- 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
Definitions
- the present invention relates to the field of the treatments for the passivation of tinned stainless steel strip with a Chrome-free passivation film, in order to improve the environmental impact of the related technologies .
- coated steels prior to the end use thereof, should be passivated when employed tel quel, or be subjected to a surface treatment in order to improve the adhesion of optional coatings or some performances, like, e.g., the corrosion resistance.
- the passivation coating may be construed as a mixture of corrosion products of the metallic substrate and of various reduced species deriving from the conversion bath.
- Typical examples of passivation treatment are chromate/phosphate-based systems, accounting for a considerable share of the market of surface conversion processes and products.
- the main passivation techniques provide the mere dipping of the product to be passivated, or the applying of a cathode current, often allowing more rapid forming times, thereto.
- the tinned stainless steel strip is, e.g., conventionally passivated with Chrome salt (Sodium dichromate, Na 2 Cr 2 0 7 ) -based solutions.
- Chrome salt Sodium dichromate, Na 2 Cr 2 0 7
- Chrome-based passivation with other likewise effective passivations based on Chrome-free solutions.
- the present invention meets this demand.
- an object of the present invention is a process for the passivation of tinned stainless steel strip with a Chrome-free passivation film, characterised in that it comprises the step of dipping, optionally applying a cathode current, the tinned strip in a passivation bath comprising at least one salt of a transition metal selected from Cobalt, Titanium, Zirconium and Molybdenum.
- the passivation bath is an aqueous solution of Cobalt sulfate heptahydrate (CoS0 • 7H 2 0) , Potassium Titanium fluoride (K 2 TiF 6 ) and Sodium nitrate (NaN0 3 ) .
- the process features are as follows: passivation bath composition expressed in g/1
- the passivation bath is an aqueous solution of Potassium Titanium fluoride (K 2 TiF 6 ) and Sodium nitrate (NaN0 3 ) .
- the process features are as follows: passivation bath composition expressed in g/1
- the passivation bath is an aqueous solution containing
- the passivation bath is an aqueous solution containing Titanium oxalate.
- the process features are as follows: passivation bath composition expressed in g/1
- the passivation bath is an aqueous solution containing Sodium molybdate.
- the process features are as follows: passivation bath composition expressed in g/1
- a further object of the present invention is a tinned stainless steel strip, passivated with the abovedisclosed process.
- Another further object of the present invention is a tinned stainless steel strip, passivated with the abovedisclosed process, painted with Chrome- free paints.
- Another object of the present invention is the use of the tinned stainless steel strip, passivated and painted without use of Chrome, for the production of tinned goods.
- Fig. 1 shows the potentiodynamic polarization curves in citrate buffer, at pH 6, scanning speed 0.2 mV/s, 50°C, for a tinned strip, not passivated (dotted curve), passivated with a Chrome-based solution (broken-line curve) , and passivated according to the invention (solid curve) with the following process features: passivation bath containing 15 g/1 CoS0 4 -7H 2 0, 15 g/1 K 2 TiF 6 and 5 g/1 NaN0 3 (electrolyte 1) ; bath temperature 50°C; current density applied 0.15 A/dm 2 ; and exposure time 1 s.
- Fig. 2 shows the potentiodynamic polarization curves in citrate buffer, at pH 6,0, scanning speed 0,2 mV/s, 50°C, for a tinned strip, not passivated (dotted curve) , passivated with Chrome-based solutions (broken-line curve) , passivated according to the invention (solid curve) with the following process features: passivation bath containing 15 g/1 K 2 TiF 6 and 5 g/1 NaN0 3 (electrolyte 2); bath temperature 50°C; current density applied 0.14 A/dm 2 ; exposure time 30 s.
- Fig. 3 shows an EDS (X-ray Dispersive Energy Spectrometry Measurements) spectrum of an untreated tinned strip, to be subjected to the process for the passivation according to the invention.
- Figs. 4 and 5 show the GDOES (Glow Discharge for Optical Emission Spectrochemical Analysis) profiles for samples passivated with the electrolyte 1 and with the electrolyte 2 according to the invention, respectively.
- a tinned strip to be subjected to the process for the passivation according to the invention is characterised with the EDX (X-ray Dispersive Energy Spectrometry Measurements) technique.
- the related spectrum shown in Fig. 3, reveals the presence of Tin as a massive element and of Iron.
- the Chrome content highlighted by atomic absorption spectroscopy, ranges from 0.58 to 0.67 mg/m 2 .
- This tinned strip is subjected to passivation according to the invention, in aqueous solution at 50 °C containing 15 g/1 K 2 TiF 6 and 5 g/1 NaN0 3 , with a cathode current density equal to 0.14 A/dm 2 and an exposure time of 30 s.
- the corrosion behaviour of samples of tinned strip thus passivated is studied by potentiodynamic polarization curves and exposition tests in a 30 g/1 sodium chloride solution for 24 hours at 25°C.
- the potentiodynamic polarization curves are constructed by measuring taken with a conventional glass cell at 25°C in a solution saturated with pure Nitrogen.
- the counterelectrode is a Platinum sheet and, as reference electrode, a saturated calomel electrode (SCE) is used.
- the electrolyte is a citrate buffer, at pH 6,0.
- the scanning speed is 0.2 mV/s.
- the polarization curves are plotted after the stabilization of the corrosion potential (about 90 min) . Fig.
Abstract
Process for the passivation of tinned stainless steel strip with a Chrome-free passivation film, characterised in that it comprises the step of dipping, optionally applying a cathode current, the tinned strip in a passivation bath comprising at least one salt of a transition metal selected from Cobalt, Titanium, Zirconium and Molybdenum. The present invention further relates to the passivated tinned strip thus obtainable, to the tinned strip passivated and painted with Chrome-free paint, and to the use thereof for the production of tinned goods.
Description
"PROCESS FOR THE PASSIVATION OF TINNED STAINLESS STEEL
STRIP WITH A CHROME-FREE PASSIVATION FILM"
DESCRIPTION
The present invention relates to the field of the treatments for the passivation of tinned stainless steel strip with a Chrome-free passivation film, in order to improve the environmental impact of the related technologies .
As it is known, coated steels, prior to the end use thereof, should be passivated when employed tel quel, or be subjected to a surface treatment in order to improve the adhesion of optional coatings or some performances, like, e.g., the corrosion resistance.
In the state of the art, the most widely adopted passivation or surface conversion treatments utilize solutions containing Chrome in the form of sodium dichromate .
These treatments are aimed both to the conversion of the metallic substrate having a protective function in mildly aggressive environments, and to the preparation of the surface in order to improve the adhesion of subsequent protective layers.
The passivation coating may be construed as a mixture of corrosion products of the metallic substrate and of various reduced species deriving from the conversion bath. Typical examples of passivation treatment are chromate/phosphate-based systems, accounting for a considerable share of the market of surface conversion processes and products. The main passivation techniques provide the mere dipping of the product to be passivated, or the applying of a cathode current, often allowing more rapid forming times, thereto.
The need to improve the environmental impact and the severity of the Acts regulating the treatment of toxic substances, like, e.g., the heavy metals, and hence the need to treat the scouring waters and the exhausts, has
raised the demand of a passivation treatment of the metal surfaces which be totally void of toxic substances.
The tinned stainless steel strip is, e.g., conventionally passivated with Chrome salt (Sodium dichromate, Na2Cr207) -based solutions. As Chrome is a highly toxic substance entailing dire environmental impact problems, there ensues the problem of replacing the Chrome-based passivation with other likewise effective passivations based on Chrome-free solutions. The present invention meets this demand. In fact, an object of the present invention is a process for the passivation of tinned stainless steel strip with a Chrome-free passivation film, characterised in that it comprises the step of dipping, optionally applying a cathode current, the tinned strip in a passivation bath comprising at least one salt of a transition metal selected from Cobalt, Titanium, Zirconium and Molybdenum.
In an embodiment of the invention, the passivation bath is an aqueous solution of Cobalt sulfate heptahydrate (CoS0 • 7H20) , Potassium Titanium fluoride (K2TiF6) and Sodium nitrate (NaN03) . In a variant of this process, the process features are as follows: passivation bath composition expressed in g/1
- CoS04.7H20 10-15 - K2TiF6 10-15
- NaN03 4-8 and water q.s. to 100; bath temperature 50-65°C; cathode current density 0.10-0.15 A/dm2; and exposure time 1-5 s. In a second embodiment of the process according to the invention, the passivation bath is an aqueous solution of Potassium Titanium fluoride (K2TiF6) and Sodium nitrate (NaN03) . In a variant of this process, the process features are as follows: passivation bath composition expressed in g/1
- K2TiF6 10 - 15
- NaN03 4 - 8
and water q.s. to 100; bath temperature 50-60°C; cathode current density 0.10-0.15 A/dm2; and exposure time 10-30 sec.
In a third embodiment of the present invention, the passivation bath is an aqueous solution containing
Zirconium sulfate. In a variant of this process, the process features are as follows: passivation bath composition
- Zr(S04)2 20 g/1 - H2S04 0,5 M and water q.s. to 100; bath temperature 50-60°C; cathode current density 0.1-0.2 A/dm2 and exposure time 5-10 s.
In a fourth embodiment according to the present invention, the passivation bath is an aqueous solution containing Titanium oxalate. In a variant of this process, the process features are as follows: passivation bath composition expressed in g/1
- Ti2(C2O4)3.10 H20 15-20 - K2C204.H20 3-8 and water q.s. to 100; bath temperature 50-65°C; cathode current density 0.1-0.2 A/dm2 and exposure time 5-10 s.
In a fifth embodiment according to the present invention, the passivation bath is an aqueous solution containing Sodium molybdate. In a variant of this process, the process features are as follows: passivation bath composition expressed in g/1
- Na2Mo04 15-20 - Na2S203 2-4 and water q.s. to 100; bath temperature 40-45°C; cathode current density 0.1-0.15 A/dm2 and exposure time 5-10 s.
A further object of the present invention is a tinned stainless steel strip, passivated with the abovedisclosed process.
Another further object of the present invention is a
tinned stainless steel strip, passivated with the abovedisclosed process, painted with Chrome- free paints.
Finally, another object of the present invention is the use of the tinned stainless steel strip, passivated and painted without use of Chrome, for the production of tinned goods.
Hereto, the present invention has merely been outlined. Hereinafter, with the aid of the following Figs, and of the example, a more detailed description of specific embodiments thereof will be given, aimed at making apparent the purposes, the features, the advantages and the operation modes thereof.
Fig. 1 shows the potentiodynamic polarization curves in citrate buffer, at pH 6, scanning speed 0.2 mV/s, 50°C, for a tinned strip, not passivated (dotted curve), passivated with a Chrome-based solution (broken-line curve) , and passivated according to the invention (solid curve) with the following process features: passivation bath containing 15 g/1 CoS04-7H20, 15 g/1 K2TiF6 and 5 g/1 NaN03 (electrolyte 1) ; bath temperature 50°C; current density applied 0.15 A/dm2; and exposure time 1 s.
Fig. 2 shows the potentiodynamic polarization curves in citrate buffer, at pH 6,0, scanning speed 0,2 mV/s, 50°C, for a tinned strip, not passivated (dotted curve) , passivated with Chrome-based solutions (broken-line curve) , passivated according to the invention (solid curve) with the following process features: passivation bath containing 15 g/1 K2TiF6 and 5 g/1 NaN03 (electrolyte 2); bath temperature 50°C; current density applied 0.14 A/dm2; exposure time 30 s.
Fig. 3 shows an EDS (X-ray Dispersive Energy Spectrometry Measurements) spectrum of an untreated tinned strip, to be subjected to the process for the passivation according to the invention. Figs. 4 and 5 show the GDOES (Glow Discharge for Optical Emission Spectrochemical Analysis) profiles for samples passivated with the electrolyte 1 and with the
electrolyte 2 according to the invention, respectively. EXAMPLE
A tinned strip to be subjected to the process for the passivation according to the invention is characterised with the EDX (X-ray Dispersive Energy Spectrometry Measurements) technique. The related spectrum, shown in Fig. 3, reveals the presence of Tin as a massive element and of Iron. The Chrome content, highlighted by atomic absorption spectroscopy, ranges from 0.58 to 0.67 mg/m2.
This tinned strip is subjected to passivation according to the invention, in aqueous solution at 50 °C containing 15 g/1 K2TiF6 and 5 g/1 NaN03, with a cathode current density equal to 0.14 A/dm2 and an exposure time of 30 s.
The corrosion behaviour of samples of tinned strip thus passivated is studied by potentiodynamic polarization curves and exposition tests in a 30 g/1 sodium chloride solution for 24 hours at 25°C. The potentiodynamic polarization curves are constructed by measuring taken with a conventional glass cell at 25°C in a solution saturated with pure Nitrogen. The counterelectrode is a Platinum sheet and, as reference electrode, a saturated calomel electrode (SCE) is used. The electrolyte is a citrate buffer, at pH 6,0. The scanning speed is 0.2 mV/s. The polarization curves are plotted after the stabilization of the corrosion potential (about 90 min) . Fig. 2 shows the potentiodynamic polarization curve of the tinned strip passivated as abovedisclosed (solid curve) , in comparison to the potentiodynamic polarization curves of tinned strip not passivated (dotted curve) and of tinned strip passivated with a Chrome-based solution (broken-line curve) . The result of the exposure tests confirms the results yielded by the polarization curves. The samples passivated according to the abovedescribed embodiment of
the invention exhibit optimum behaviour.
The surface of samples of tinned strip passivated as aboveindicated was analysed by SEM (Scanning Electron Microscopy) , EDS (X-ray Dispersive Energy Spectrometry Measurements) , GDOS (Glow Discharge for Optical Emission Spectrochemical Analysis) (profile shown in Fig. 4), and XPS (X-ray Photoelectron Spectroscopy) techniques. The results of these surface analyses highlight features comparable to those of the surfaces of tinned strip passivated with Chrome-based solutions.
Claims
1. A process for the passivation of tinned stainless steel strip with a Chrome-free passivation film, characterised in that it comprises the step of dipping, optionally applying a cathode current, the tinned strip in a passivation bath comprising at least one salt of a transition metal selected from Cobalt, Titanium Zirconium and Molybdenum.
2. The process for the passivation of tinned stainless steel strip with a Chrome-free passivation film according to claim 1, wherein the passivation bath is an aqueous solution of Cobalt sulfate heptahydrate (CoS04 -7H20) , Potassium Titanium fluoride (K2TiF6) and Sodium nitrate (NaN03) .
3. The process for the passivation of tinned stainless steel strip with a Chrome-free passivation film according to claim 2 , wherein the process features are as follows: passivation bath composition expressed in g/1
- CoS04 - 7H20 10 - 15 - K2TiF6 10 - 15
- NaN03 4 - 8 and water q.s. to 100; bath temperature 50-65°C; cathode current density 0.10-0.15 A/dm2; and exposure time 1-5 s.
4. The process for the passivation of tinned stainless steel strip with a Chrome-free passivation film according to claim 1, wherein the passivation bath is an aqueous solution of Potassium Titanium fluoride (K2TiF6) and Sodium nitrate (NaN03) .
5. The process for the passivation of tinned stainless steel strip with a Chrome-free passivation film according to claim 4, wherein the process features are as follows: passivation bath composition expressed in g/1
- K2TiF6 10-15 - NaN03 4-8, and water q.s. to 100; bath temperature 50-60°C; cathode current density 0.10-0.15 A/dm2; and exposure time 10-30 s.
6. The process for the passivation of tinned stainless steel strip with a Chrome-free passivation film according to claim 1, wherein the passivation bath is an aqueous solution containing Zirconium sulfate.
7. The process for the passivation of tinned stainless steel strip with a Chrome-free passivation film according to claim 6, wherein the process features are as follows: passivation bath composition - Zr(S04)2 15-20 g/1
- H2S04 0,5 M and water q.s. to 100; bath temperature 50-60°C; cathode current density 0.1-0.2 A/dm2 and exposure time 5-10 sec.
8. The process for the passivation of tinned stainless steel strip with a Chrome-free passivation film according to claim 1, wherein the passivation bath is an aqueous solution containing Titanium oxalate.
9. The process for the passivation of tinned stainless steel strip with a Chrome-free passivation film according to claim 8, wherein the process features are as follows: passivation bath composition expressed in g/1
- Ti2 ( C2O4 ) 3 . 10 H20 15 - 20
- K2C204 . H20 3 - 8 and water q.s. to 100; bath temperature 50-65°C; cathode current density about 0.10-0.20 A/dm2 and exposure time 5-10 s.
10. The process for the passivation of tinned stainless steel strip with a Chrome-free passivation film according to claim 1, wherein the passivation bath is an aqueous solution containing Sodium molybdate .
11. The process for the passivation of tinned stainless steel strip with a Chrome-free passivation film according to claim 10, wherein the process features are as follows: passivation bath composition expressed in g/1
- Na2Mo04 15 - 20
- Na2S203 2 - 4 and water q.s. to 100; bath temperature 40-45°C; cathode current density 0.1-0.15 A/dm2 and exposure time 5-10 s.
12. A tinned stainless steel strip, characterised in that it is obtainable with the process recited in claims 1 to 11.
13. The tinned stainless steel strip, passivable according to claim 12, characterised in that it is painted with Chrome-free paints.
14. A use of the tinned stainless steel strip, passivated and painted with Chrome- free paints according to claim 13, for the production of tinned goods.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AU2002225326A AU2002225326A1 (en) | 2000-12-19 | 2001-12-19 | Process for the passivation of tinned stainless steel strip with a chrome-free passivation film |
| EP01994948A EP1368515A2 (en) | 2000-12-19 | 2001-12-19 | Process for the passivation of tinned stainless steel strip with a chrome-free passivation film |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| IT2000RM000679A IT1316032B1 (en) | 2000-12-19 | 2000-12-19 | PROCEDURE FOR THE PASSIVATION OF STAINLESS STEEL BAND WITH CHROMIUM-FREE PASSIVATION FILM. |
| ITRM2000A000679 | 2000-12-19 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| WO2002050341A2 true WO2002050341A2 (en) | 2002-06-27 |
| WO2002050341A3 WO2002050341A3 (en) | 2003-09-25 |
Family
ID=11455067
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/IT2001/000643 WO2002050341A2 (en) | 2000-12-19 | 2001-12-19 | Process for the passivation of tinned stainless steel strip with a chrome-free passivation film |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP1368515A2 (en) |
| AU (1) | AU2002225326A1 (en) |
| IT (1) | IT1316032B1 (en) |
| WO (1) | WO2002050341A2 (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7713013B2 (en) | 2004-10-08 | 2010-05-11 | Innozinc, Inc. | Supporting device |
| WO2011036260A3 (en) * | 2009-09-24 | 2011-06-16 | Stefan Dameron | Method for galvanizing and passivation |
| CN104562029A (en) * | 2014-12-26 | 2015-04-29 | 江苏新华明机械制造实业有限公司 | Surface treatment process for framework stamping part of high-frequency tuner |
| CN109975340A (en) * | 2017-12-26 | 2019-07-05 | 上海梅山钢铁股份有限公司 | The Microstructural Analysis of aluminium plating zinc plate chromium-free deactivation film thickness |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102268664B (en) * | 2011-07-28 | 2013-04-17 | 顺德职业技术学院 | Chromium-free passivating solution used for black passivation treatment of zinc plating and preparation method thereof |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4298404A (en) * | 1979-09-06 | 1981-11-03 | Richardson Chemical Company | Chromium-free or low-chromium metal surface passivation |
| US4385940A (en) * | 1980-01-11 | 1983-05-31 | Kobe Steel, Limited | Method for anticorrosive treatment of galvanized steel |
| US4444601A (en) * | 1979-09-06 | 1984-04-24 | Richardson Chemical Company | Metal article passivated by a bath having an organic activator and a film-forming element |
| EP0732425A1 (en) * | 1995-03-13 | 1996-09-18 | British Steel plc | Passivation treatment of tinplate |
| US5607521A (en) * | 1991-11-15 | 1997-03-04 | Ipu Instituttet For Produktudvikling | Method for post-treatment of an article with a metallic surface as well as a treatment solution to be used in the method |
| DE19745801A1 (en) * | 1997-10-16 | 1999-04-22 | Henkel Kgaa | Method for coating metals with organic film-former solutions or dispersions containing corrosion inhibitor pigment precursors |
-
2000
- 2000-12-19 IT IT2000RM000679A patent/IT1316032B1/en active
-
2001
- 2001-12-19 WO PCT/IT2001/000643 patent/WO2002050341A2/en not_active Application Discontinuation
- 2001-12-19 AU AU2002225326A patent/AU2002225326A1/en not_active Abandoned
- 2001-12-19 EP EP01994948A patent/EP1368515A2/en not_active Withdrawn
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4298404A (en) * | 1979-09-06 | 1981-11-03 | Richardson Chemical Company | Chromium-free or low-chromium metal surface passivation |
| US4444601A (en) * | 1979-09-06 | 1984-04-24 | Richardson Chemical Company | Metal article passivated by a bath having an organic activator and a film-forming element |
| US4385940A (en) * | 1980-01-11 | 1983-05-31 | Kobe Steel, Limited | Method for anticorrosive treatment of galvanized steel |
| US5607521A (en) * | 1991-11-15 | 1997-03-04 | Ipu Instituttet For Produktudvikling | Method for post-treatment of an article with a metallic surface as well as a treatment solution to be used in the method |
| EP0732425A1 (en) * | 1995-03-13 | 1996-09-18 | British Steel plc | Passivation treatment of tinplate |
| DE19745801A1 (en) * | 1997-10-16 | 1999-04-22 | Henkel Kgaa | Method for coating metals with organic film-former solutions or dispersions containing corrosion inhibitor pigment precursors |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7713013B2 (en) | 2004-10-08 | 2010-05-11 | Innozinc, Inc. | Supporting device |
| WO2011036260A3 (en) * | 2009-09-24 | 2011-06-16 | Stefan Dameron | Method for galvanizing and passivation |
| CN104562029A (en) * | 2014-12-26 | 2015-04-29 | 江苏新华明机械制造实业有限公司 | Surface treatment process for framework stamping part of high-frequency tuner |
| CN109975340A (en) * | 2017-12-26 | 2019-07-05 | 上海梅山钢铁股份有限公司 | The Microstructural Analysis of aluminium plating zinc plate chromium-free deactivation film thickness |
Also Published As
| Publication number | Publication date |
|---|---|
| EP1368515A2 (en) | 2003-12-10 |
| IT1316032B1 (en) | 2003-03-26 |
| WO2002050341A3 (en) | 2003-09-25 |
| ITRM20000679A1 (en) | 2002-06-19 |
| ITRM20000679A0 (en) | 2000-12-19 |
| AU2002225326A1 (en) | 2002-07-01 |
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