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
• • 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
  • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
  • C23F1/00—Etching metallic material by chemical means
  • C23F1/10—Etching compositions
  • C23F1/14—Aqueous compositions
  • C23F1/16—Acidic compositions
• • 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
  • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
  • C23F3/00—Brightening metals by chemical means
  • C23F3/04—Heavy metals
  • C23F3/06—Heavy metals with acidic solutions

Definitions

• the present invention relates to a composition having high stabilizing properties, more particularly in the case of inorganic peroxides used in the context of industrial applications.
• It relates more particularly to a stabilizing composition of inorganic peroxides used in the pickling baths of metal surfaces.
• Strippers of the type mentioned generally contain nitric-hydrofluoric mixtures or mixtures of sulfuric-nitric and hydrofluoric acids, to which process correctors which may be surfactants have been added, in order to improve their wetting characteristics or inhibitors for standardize the chemical action.
• pickling baths have recently been proposed. which provide an alternative solution to traditional processes.
• the auxiliary mechanical action normally provides for the creation of turbulence in the pickling solution, either by stirring the liquid or by blowing air into the baths so as to promote the detachment of the oxides from the metal surfaces.
• the absence of nitric acid in these baths is compensated for by the presence of inorganic peroxides such as hydrogen peroxide.
• inorganic peroxides not only replaces the oxidizing action of nitric acid, but it also promotes pickling and passivation of the metal surface.
• control of the peroxides present in the baths should normally be carried out using redox measuring instruments which, as is known, are not only very expensive to purchase, but also have a limited longevity when they are used for this specific purpose.
• the baths containing peroxides also offer limited stability, due to the presence of metals which catalyze the decomposition of the peroxides.
• nitric acid-free baths allow for the moment to considerably reduce the degree of pollution, on the other hand, it is necessary either to operate at temperatures generally higher than the temperatures usual, either to carry out costly modifications of the equipment, the latter having to be equipped with means for heating and agitating the baths or means for blowing air into these same baths, and therefore providing for automatic control and permanent peroxide contained in the pickling mixture.
• peroxidized chemical attack compositions of effective metals must contain a certain amount of 3-amino-1,2,4-triazole, a constituent which acts both as an accelerator of chemical attack and as stabilizer (page 2, lines 20 to 26).
• an important objective of the present invention is to produce a composition having high stabilizing properties, and this, more particularly with regard to the inorganic peroxides used in the context of industrial applications, this composition having to be able to stabilize peroxides while avoiding undesirable decompositions of these same peroxides in the presence of metals, even in high concentrations, and more specifically in the context of acid pickling processes replacing nitric mixtures.
• Another important objective of the present invention is to provide a composition offering high stabilizing properties and capable of increasing the oxidation action of peroxides, more particularly hydrogen peroxide in contact with surfaces metallic, and this by means of an oxidation-dissolution action of oxides which is extremely rapid, even at room temperature.
• Another important objective of the present invention consists in producing a composition offering high stabilizing properties and which is capable of providing a pickling system which would replace the nitric acid baths currently used, without however the need to modify the equipment used and without reducing the treatment time at the same temperature.
• Another objective - and not least - of the present invention is to provide a composition with high stabilizing properties which makes it possible to eliminate the heating of the solutions and to eliminate their agitation as well as the permanent control of the level of peroxides contained in the baths. .
• the invention relates to a stabilizing composition for inorganic peroxides intended for baths for the surface treatment of metal parts, according to which it comprises at least one activating agent selected from benzotriazoles, imidazole and carboxyimidazoles or their derivatives.
• composition with high stabilizing properties in particular for the inorganic peroxides used in the context of 'applications industrial.
• inorganic peroxides is intended to denote hydrogen peroxide, inorganic peracids and their salts, more particularly perboric, perphosphoric and persulfuric acids and their alkali or alkaline earth metal salts, as well as peroxides of alkali and alkaline earth metals such as sodium, calcium and magnesium peroxides.
• hydrogen peroxide or inorganic peracids are used. Very good results have been obtained with hydrogen peroxide.
• surface treatment of metal parts is intended to denote the treatment of metal parts using a bath comprising one or more acidic compounds and one or more oxidizing compounds, in particular with a view to stripping them by removing the oxides covering their surface, or passivate them or improve the surface finish, more particularly to polish them and / or perform a polishing treatment.
• the composition is intended to be incorporated into the surface treatment baths of metal parts. It generally does not itself contain peroxide, which is added to the treatment bath independently.
• the stabilizing action of peroxides and their capacity to accelerate deoxidation depend on the composition of the baths in which the traditional standard nitric-hydrofluoric mixture is replaced, as regards the nitric part, by oxygenated water in the H2O2-HNO3 molar proportion of 1/2 to 2/1 but preferably 1/1, while the acid part of the nitric acid is replaced by sulfuric acid in the HNO3-H2SO4 molar proportion of 1 / 2 to 2.5 / 1, but preferably 1 / 1.3.
• the acid part with regard to sulfuric acid may be replaced, in whole or in part, by inorganic acids of phosphoric, sulfamic or other type, insofar as they do not cause a negative interaction with the stabilizer of the hydrogen peroxide or peroxide.
• the hydrofluoric part can for its part comprise at least one compound chosen from fluorinated acids or fluorinated salts and the percentage is maintained within the usual standard values that are known.
• the bath thus obtained requires the presence of a peroxide stabilizing agent in the proportion of 1/100 to 1/1, but preferably from 1/30 to 1/2, depending on the peroxide used.
• the stabilizing agent used for the baths of these compositions and which constitutes the object of the present invention can comprise, in addition to the activating agent at least, another compound chosen from stabilizing agents, the solvent compounds of the stabilizing agent, oxidation catalysts, wetting agents capable of resisting in an oxidizing acid environment, optionally phosphates or phosphonates as co-adjuvants for precipitation and deactivation of dissolved metals, and finally, inorganic and / or organic acids as product standardizers.
• the composition also comprises at least one stabilizing agent.
• the stabilizing agent in particular, it may comprise one or more aromatic or cyclic rings or one or more aliphatic chains. It can also contain at least one group chosen from hydroxyl, carboxylic, sulfonate and phosphate groups.
• the term “sulfonate and phosphate groups” is intended to denote here both the sulfonic and phosphoric groups and their salts. It can also contain at least one group chosen from esters, ethers, dienes, azoles, mercapto-azoles or combinations thereof.
• the stabilizing agent may comprise at least one compound selected from mono or polycyclic aromatic or alicyclic compounds and aliphatic compounds substituted by at least one group chosen from the groups hydroxyls, carboxyls, sulfonates, phosphates, esters, ethers, dienes, azoles and mercapto-azoles. Good results have been obtained with compounds substituted by sulfonate (or sulfonic) groups and phosphates (or phosphoric) groups or mixtures thereof. P-Toluene sulfonic acid is well suited.
• compositions according to the invention can comprise at least one solvent compound for the stabilizing agent.
• the solvent compound also called dissolving part of the stabilizing agent described above can include alcohols, glycols, polyethers, dimethylformamide, N-methylpyrrolidone, ketones, polyglycols, esters, low-weight condensates molecular or organic groups characterized by a reasonable solubility in water, resistant in an acidic environment and having a good dissolving power of the organic components used as stabilizing agents and having zero or low solubility in water or in inorganic acids at use concentrations.
• the solvent compound of the stabilizing agent preferably comprises at least one compound selected from alcohols, glycols and polyglycols.
• the solvent compound can also contain, in admixture with said alcohols, glycols and / or polyglycols at least one adjuvant chosen from dimethylformamide and N-methylpyrrolidone.
• the solvent compound can include polyesters, ketones, esters, low molecular weight condensates or organic groups with good water solubility and resistance in an acidic medium.
• the activating agent which can also also be used independently of the stabilizing agents or solvent compounds mentioned above, comprises cyclic, aromatic amine components, derivatives of imidazoles and / or carboxy-imidazoles, and / or aliphatic amines.
• compositions according to the invention can also contain at minus one compound chosen from oxidation catalysts made up of metals and wetting agents resistant in an oxidizing acid medium.
• the oxidation catalysts can comprise at least one metal belonging to the first, second, third or fourth group. These are present in a percentage varying from 2 to 20,000 ppm and preferably from 10 to 3,000 ppm.
• group is meant a group which corresponds to a family represented in the same column of the periodic table of the elements.
• the metals of group 3 have proved to be interesting and good results have been obtained with aluminum.
• the composition may also comprise at least one wetting agent stable in oxidizing acid medium, that is to say an agent capable of modifying the surface tension at the solid / liquid interface in order to improve the wetting of metal parts by the treatment bath.
• This wetting agent should be selected from those which are chemically inert in the presence of an acidic and oxidizing aqueous solution and, in particular, acidic aqueous solutions of peroxides.
• wetting agents capable of resisting in an oxidizing acid environment consist of nonionic, anionic, amphoteric or cationic condensates or fluorinated derivatives, or a mixture of these. Good results have been obtained with fluorinated anionic surfactants and ethylene glycol condensates with alkylphenols and their mixtures.
• the pickling bath constituted in this way and having the stabilizing agent described above can operate from a pH equal to 2.5 and up to a pH of 0.0, but usually it operates at a pH below 1.3.
• the pickling bath can operate at pH values equal to or less than 0.3.
• the stabilizing composition reduces the oxidation potential of the iron / nickel / chromium sub-oxides and catalyze their oxidation, thereby promoting the transformation into soluble oxides.
• the presence in a pickling bath of the stabilizing composition which is the subject of the present invention makes it possible to carry out pickling in a time and at extremely competitive temperatures compared to the baths currently used.
• composition according to the invention it is also possible to incorporate precipitation additives and, consequently, deactivation of the dissolved metals originating from the dissolution of the oxides or from the surface part of the metal part under the action of the treatment bath.
• adjuvants can be soluble inorganic or organic salts whose anion combines with the cation of the metal or metals dissolved in the bath to form a salt whose solubility product is very low under the conditions prevailing in the bath, for example less than 10 ⁇ 5 gram ion.
• the composition can also comprise at least one compound chosen from phosphates and phosphonates as co-adjuvants for precipitation and deactivation of dissolved metals and inorganic and organic acids as treatment-leveling agents. These are used to standardize the product.
• the precipitation co-adjuvants can be chosen from phosphates and phosphonates of all types. Pyrophosphates are well suited.
• the stripping action obtained through the use of the composition having high stabilizing properties and which is the subject of the present invention normally does not require any agitation of the baths or of the elements which are immersed therein.
• the invention therefore therefore also relates to methods for treating metallic surfaces, more particularly stainless steel surfaces in the presence of the stabilizing compositions described above using at least one inorganic peroxide at acid pH. This treatment is then followed by at least one rinsing. During at least one of the treatment or rinsing phases, agitation of the bath can be obtained using ultrasound.
• variable doses of the various active compounds and in particular of acid, of inorganic peroxides and of stabilizing composition according to the invention can be used. It is thus possible to use 0.1 to 5 moles and preferably 0.5 to 3 moles of peroxidized compound per liter of solution.
• the amount of acid is added to maintain the pH at the desired values.
• the acids which can be used for this purpose mention may be made of sulfuric acid which is particularly suitable. It can be used in combination with fluorides and for example with hydrofluoric acid in variable ratios. In this case, the sulfuric acid / hydrofluoric acid weight ratios generally do not exceed 500 and, more often than not, 100. Likewise these ratios are generally not less than 0.1 and, most often, not less than 1.
• the invention also relates to the use of the composition described above for the preparation of a pickling, passivating, polishing and / or polishing bath for metals.
• a typical composition includes: 98% sulfuric acid from 4 to 300 g / l 100% hydrogen peroxide from 0.2 to 100 g / l hydrofluoric acid from 0.5 to 10 g / l stabilizing composition from 0.2 to 30 g / l where the standard stabilizing composition consists of: p-toluene sulfonic acid 10 N-methylpyrrolidone 22 ethylene glycol 5 benzotriazole + imidazole (about 50% - 50%) 3 aluminum +++ 3 fluorinated anionic surfactant 0.5 (FC R 95: registered trademark of 3M company) ethylene oxide and octylphenol condensate 5 pyrophosphate ion 4 sulfuric acid 10 citric acid 2 water complement to 100
• Stability tests were then carried out by incorporating into the mixture, consisting of 180 g / l of sulfuric acid, 40 g / l of H2O2 and 30 g / l of hydrofluoric acid, an amount of 8 g / l of AISI 304 steel and then relating the H2O2 content to the initial values.
• composition of the invention having high stabilizing properties and more particularly in the case of inorganic peroxides used in the context of industrial applications, offers many advantages of all kinds.
• the temperatures of use of pickling baths appear to be equal to or really lower than the temperatures which are those of baths based on nitric and hydrofluoric acid and therefore, highly polluting.
• composition having important stabilizing properties, object of the present invention By using in a bath the composition having important stabilizing properties, object of the present invention, there is no emission of nitrous vapors, and the emission of acids, for example fluorides, is itself extremely reduced.
• Intergranular corrosion is also eliminated, among other things, and the process can be adapted to different types of stainless steels such as, for example, steels from the AISI 400 series (pickling is generally difficult with traditional systems). or still, the steels of the AISI 300 series. It is understood that the compositions according to the invention are also well suited for the treatment of other types of stainless steels.
• the use of the stabilizing composition described above makes it possible in particular to considerably reduce the consumption of inorganic peroxide, more particularly hydrogen peroxide, while allowing equal or really lower pickling times. , even up to 50%, compared to the stripping times required in the case of traditional baths.

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• 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)
• Detergent Compositions (AREA)
• Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)
• ing And Chemical Polishing (AREA)
• Heterocyclic Carbon Compounds Containing A Hetero Ring Having Oxygen Or Sulfur (AREA)

Applications Claiming Priority (3)

Publications (2)

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• 1991
  • 1991-10-25 IT ITMI912845A patent/IT1251431B/it active IP Right Grant
• 1992
  • 1992-10-23 CA CA002121691A patent/CA2121691A1/fr not_active Abandoned
  • 1992-10-23 BR BR9206668A patent/BR9206668A/pt not_active Application Discontinuation
  • 1992-10-23 DE DE69210622T patent/DE69210622T2/de not_active Expired - Fee Related
  • 1992-10-23 WO PCT/EP1992/002442 patent/WO1993008317A1/fr active IP Right Grant
  • 1992-10-23 ES ES92922319T patent/ES2089573T3/es not_active Expired - Lifetime
  • 1992-10-23 JP JP5507462A patent/JPH07500378A/ja active Pending
  • 1992-10-23 US US08/211,964 patent/US5538152A/en not_active Expired - Fee Related
  • 1992-10-23 KR KR1019940701353A patent/KR100249061B1/ko not_active IP Right Cessation
  • 1992-10-23 EP EP92922319A patent/EP0609342B1/fr not_active Expired - Lifetime
• 1994
  • 1994-04-22 FI FI941893A patent/FI100727B/fi active

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