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EP0795627B1 - Agent décapant pour acier inoxydable - Google Patents

Agent décapant pour acier inoxydable Download PDF

Info

Publication number
EP0795627B1
EP0795627B1 EP97102946A EP97102946A EP0795627B1 EP 0795627 B1 EP0795627 B1 EP 0795627B1 EP 97102946 A EP97102946 A EP 97102946A EP 97102946 A EP97102946 A EP 97102946A EP 0795627 B1 EP0795627 B1 EP 0795627B1
Authority
EP
European Patent Office
Prior art keywords
pickling
agent according
pickling agent
weight
calculated
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.)
Expired - Lifetime
Application number
EP97102946A
Other languages
German (de)
English (en)
Other versions
EP0795627A1 (fr
Inventor
Harald Werner
Bernd Schaarschuh
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Chemetall GmbH
Original Assignee
Chemetall GmbH
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Chemetall GmbH filed Critical Chemetall GmbH
Publication of EP0795627A1 publication Critical patent/EP0795627A1/fr
Application granted granted Critical
Publication of EP0795627B1 publication Critical patent/EP0795627B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

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
    • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
    • C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
    • C23G1/02—Cleaning or pickling metallic material with solutions or molten salts with acid solutions
    • C23G1/08—Iron or steel
    • C23G1/086—Iron or steel solutions containing HF

Definitions

  • the invention relates to a pickling agent for stainless steel with a Hydrogen fluoride content.
  • the most important acids for pickling stainless steels or Acid mixtures are hydrofluoric acid, hydrofluoric acid / nitric acid, Hydrofluoric acid / sulfuric acid with some considerable additives EisenIII compounds already in the starting phase of the pickling agent.
  • Some of the mordants contain hydrogen peroxide, with which Help the iron II ions dissolving as a result of the pickling attack are oxidized to iron III ions.
  • Examples of such Pickling agents are described in WO 87/01739, DE-A-3825857, DE-A-4417284 and EP-A-505606.
  • the known pickling agents stick various disadvantages. A disadvantage is often that low pickling speed.
  • the object of the invention is to provide a pickling agent represent the known, especially the aforementioned disadvantages does not have, economical and easy to use is as well as metallic bright, pure stainless steel surfaces leaves.
  • cerium and / or cobalt compounds for a considerable improvement in the pickling effect of the pickling agent are responsible. This can be in the case of the cer CeIII and CerIV compounds, in the case of cobalt around CoII and Trade CoIII compounds.
  • the compounds can be soluble or to be insoluble.
  • Particularly suitable compounds are, for example, cerium dioxide, CerIV sulfate, basic CerIV nitrate (Ce (OH) (NO 3 ) 3 • 3H 2 O), CeIII nitrate (Ce (NO 3 ) 3 • 6H 2 O), ammonium cerium IV nitrate ((NH 2 ) 2 [Ce (NO 3 ) 6 ]), decamine- ⁇ -peroxodicobalt III nitrate ([(NH 3 ) 5 -Co-OO-Co (NH 3 ) 5 ] (NO 3 ) 4 • 2H 2 O).
  • cobalt II nitrate and sodium hexanitrocobaltate Na 3 [Co (NO 2 ) 6 ] are particularly outstanding.
  • the pickling agent should be practically free of chelating agents and organic acids. It is also advantageous that Pickling agents according to the invention are also practically free of sulfite, Keep chloride and bromide ions. These measures have an effect especially on the treatment or disposal of rinsing water and processed pickling agent.
  • the mordant according to the invention is as immersion stain, as Spray stain and can be used as pickling paste.
  • polysaccharides Magnesium compounds and / or barium sulfate are preferred.
  • the amounts required for polysaccharides are about 0.3 to 3 % By weight, for magnesium compounds about 1 to 8% by weight (as Magnesium calculated) and for barium sulfate about 10 to 60 wt .-%, each related to the finished mordant.
  • the Quantities apply to the lower ranges for spray stain upper areas for the pickling paste. (Thixotropy effect)
  • the mordant according to the invention additionally contains nitric acid.
  • the nitric acid content should be 0.5 to 4% by weight (calculated as HNO 3 ), in its application as spray stain or pickling paste it should be 0.5 to 6% by weight (calculated as HNO 3 ).
  • the bath temperature should not be below 5 ° C.
  • the temperature should not exceed 35 ° C be otherwise strong steam development can occur.
  • the pickling time is usually 20 to 120 minutes.
  • the exposure time should be at least 30 minutes.
  • the required pickling time depends on the temperature dependent.
  • the spray stain is usually applied by a Low pressure spray system at a pressure of 3.5 to 6 bar the pickling paste by brush application.
  • the workpieces are in the Usually with cold water under high pressure of about 120 to 180 bar hosed.
  • the mordant according to the invention is particularly suitable for Pickling of austenitic, martensitic and ferritic Steels and for special steels with titanium, vanadium, Molybdenum, niobium, tantalum and the like
  • the advantages of the pickling agent according to the invention are that bright, pure stainless steel surfaces can be achieved with a high pickling rate, although it contains no or only small amounts of nitric acid. As a result, there are no or only extremely small amounts of nitrogen oxides (NO x ) which meet the requirements with regard to the MAK value and TA-Luft, so that the otherwise expensive gas scrubbers can be dispensed with. Due to the low total acid concentration, the effort of the pickling plants for floor and wall coating is considerably reduced. The low total acid concentration also has an advantageous effect on the treatment and disposal of waste water and processed pickling agents. In particular, the salt load in the wastewater, which comes from the nitrate, is considerably reduced.
  • the service life of the pickling agent according to the invention in its Use as a dip stain is significantly longer than with conventional mordants, which also with a view Processing and disposal is important.
  • the pickling bath temperature was 22 ° C, the pickling time 45 minutes. in the Following the pickling process, the workpieces were made with cold water sprayed at a pressure of 160 bar.
  • the workpieces obtained had a bright metallic, pure Surface on.
  • the area of the welds was free of Tarnish colors and sticky welding scale.
  • a cold welded seam was used rolled stainless steel of quality 1.4301.
  • the spray stain had a temperature of 20 ° C and was with Using a diaphragm pump under a pressure of 4 bar on the Workpiece surface sprayed on. It became an even one thick order of 0.5 mm received.
  • the workpieces obtained after the pickling process showed one matt, lightened, metallic pure surface. Also in this Trap areas were free of tarnish and adhering sweat scale.
  • pickling paste was applied through the weld seams even brush application applied.
  • the thickness of the order was 1 mm, the temperature of the pickling paste was 18 ° C.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)

Claims (8)

  1. Agent décapant: pour acier inoxydable contenant de l'acide fluorhydrique, caractérisé par le fait qu'il contient de 1 à 12 % en poids d'acide fluorhydrique (HF) et en outre de 0,02 à 2 % en poids d'un composé de cérium et/ou de cobalt (cation).
  2. Agent décapant selon la revendication 1, caractérisé par le fait que le composé de cobalt est présent sous forme de nitrate de cobalt et/ou d'hexanitrocobaltate de sodium.
  3. Agent décapant selon une des revendications 1 ou 2, caractérisé par le fait qu'il est pratiquement exempt d'agents chélatants et d'acide organiques.
  4. Agent décapant selon les revendications 1, 2 ou 3, caractérisé par le fait qu'il est pratiquement exempt d'ions sulfite, chlorure et bromure.
  5. Agent décapant selon une ou plusieurs des revendications 1 à 4, caractérisé par le fait qu'il contient en outre, lorsqu'on l'utilise sous, forme de solution à pulvériser ou sous forme de pâte, des agents épaississants.
  6. Agent décapant selon la revendication 5, caractérisé par le fait qu'il contient, en tant qu'agent épaississant, des polysaccharides, des composés de magnésium et/ou du sulfate de baryum.
  7. Agent décapant selon une ou plusieurs des revendications 1 à 4, caractérisé par le fait qu'il contient, lorsqu'il est utilisé sous forme de solution pour immersion, en outre de 0,5 à 4 % en poids d'acide nitrique (HNO3).
  8. Agent décapant selon une ou plusieurs des revendications 5 ou 6, caractérisé par le fait qu'il contient, lorsqu'il est utilisé sous forme de solution à pulvériser ou sous forme de pâte, en outre de 0,5 à 6 % en poids d'acide nitrique (HNO3).
EP97102946A 1996-03-13 1997-02-22 Agent décapant pour acier inoxydable Expired - Lifetime EP0795627B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19609671A DE19609671A1 (de) 1996-03-13 1996-03-13 Beizmittel für Edelstahl
DE19609671 1996-03-13

Publications (2)

Publication Number Publication Date
EP0795627A1 EP0795627A1 (fr) 1997-09-17
EP0795627B1 true EP0795627B1 (fr) 2001-05-02

Family

ID=7788040

Family Applications (1)

Application Number Title Priority Date Filing Date
EP97102946A Expired - Lifetime EP0795627B1 (fr) 1996-03-13 1997-02-22 Agent décapant pour acier inoxydable

Country Status (3)

Country Link
EP (1) EP0795627B1 (fr)
AT (1) ATE200917T1 (fr)
DE (2) DE19609671A1 (fr)

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3280038A (en) * 1964-03-20 1966-10-18 Dow Chemical Co Method for cleaning stainless steel
JPS56130475A (en) * 1980-03-13 1981-10-13 Sumitomo Metal Ind Ltd Manufacture of hot rolled steel plate with superior chemical treatability
ES2171170T3 (es) * 1993-09-13 2002-09-01 Commw Scient Ind Res Org Tratamiento de metales por medio de una solucion de limpieza que contiene iones acidos de tierras raras.

Also Published As

Publication number Publication date
DE59703459D1 (de) 2001-06-07
EP0795627A1 (fr) 1997-09-17
ATE200917T1 (de) 2001-05-15
DE19609671A1 (de) 1997-09-18

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