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
  • 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
  • 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

Definitions

• ABSTRACT Primary Examiner-Charles E. Van Horn Assistant Examiner-Jerome W. Massie Attorney, Agent, or Firm--We'nderoth, Lind & Ponack [5 7] ABSTRACT
• the present invention relates to solutions used for chemical dissolution treatment such as, pickling, etching, chemical polishing, etc., of metallic materials.
• chemical dissolution treatment such as, pickling, etching, chemical polishing, etc.
• a considerable excess of the agent is required due to low efiiciency.
• chloride ions are contained in the solution, the dissolution rate of metallic materials is remarkably decreased.
• the present invention has overcome the above difficulties by using a solution for chemical dissolution treatment of metallic materials containing hydrogen peroxide, an acid and at least one of an alcohol polyoxyethylene ether, an alkylsulfonic acid, an alkyl hydrogen phosphate, an alkyl hydrogen phosphite, an alkyl hydrogen sulfate and their salts.
• the present invention relates to solutions used for dissolution treatment of metallic materials, more par ticularly, to solutions which comprise acid solutions containing hydrogen peroxide and a small amount of such organic compounds that no only inhibit decomposition of hydrogen peroxide but also exhibit useful fiinctions profitable to the chemical treatment.
• chemical dissolution treatment used herein refers to the treatments in general for chemically dissolving metals or metallic compounds such as oxide scale adhering to the surface of the metals, including from the technical standpoint, pickling, etching, chemical milling and chemical polishing.
• Pickling is a process in which oxide scales produced in high temperature processing of metallic materials or during their storage are removed.
• Etching and chemical milling are processes to give a desired shape to a metallic material by dissolving unnecessary parts of the mate rial.
• Chemical polishing is a treatment to produce a smooth and bright surface on metallic materials by dissolving the surface layer under a specified condition.
• Hydrogen peroxide is decomposed catalytically by the action of metallic ions dissolved in the solution. This means not only economical loss but also difficulty of stable treatment in uniformly dissolving metallic materials in the technical scale. Hydrogen peroxide is known to be unstable in itself and to be acceleratingly decomposed by the catalytic action of heavy or noble Table: 1
• Sodium stannate may often become colloidal and sticks to and stains materials under treatment. Pyrophosphoric acid is apt to be [hydrolyzed in an acid solution. Chelating agents have to be used in a large excess over the amount of metal ions dissolved, and only poor effect could be expected.
• the object of the present invention is to provide solutions for chemical dissolution treatment of metallic materials which can be applied to metallic materials constantly and uniformly for a sufiiciently long period, suppressing wasteful decomposition of hydrogen peroxide, by adding a small amount of stabilizing agent.
• Further object of this invention is to provide solutions forchemical dissolution treatment of metallic materials with which, even when the treatment solutions are contaminated by chloride ions, lustrous finished surfaces of metallic materials could be produced without decreasing the rate of dissolution of metals.
• Still further object of this invention is to provide solu tions for dissolution treatment of metallic materials which do not produce mist of acid on dissolving metallic materials.
• Another object of this invention is to provide solutions for chemical dissolution treatment of metallic materials with which red strains, that are otherwise likely to form on brass materials, could be prevented from forming.
• a solution for the chemical dissolution treatment of metallic materials comprising a mixed aqueous solution of 0.1 to 10 g/l in hydrogen-ion concentration of an acid, 0.1 to 300 g/l of hydrogen peroxide, and 0.001 to 20 g/l of at least one compound to prevent the decomposition of the hydrogen peroxide selected from the group consisting of;
• an alcohol polyoxyethylene ether represented the formula b. an alkylsulfonic acid represented by the formula XR SO H or its salts,
• the concentration of the first component, hydrogen peroxide is 0.1 to 300 g/l, preferably 1 to 200 g/l.
• the second component includes sulfuric, sulfamic, phosphoric, hydrochloric, acetic, hydrofluric, hydroborofluoric, and hexafluorohydrosilicic acids.
• sulfuric acid is generally used because it is cheap.
• Acetic acid is suitable for the dissolution treatment of lead metal and alloys thereof.
• hydrofluoric acid should be used either alone or in the form of a mixture with another acid.
• acids to be used should be chosen depending on the metals to be treated.
• the acid concentration in the solutions for chemical treatment of this invention is 0.1 to 10 g/] in terms of hydrogen-ion concentration. If the concentration is below 0.1 g/l, the solution is practically too weak to dissolve metals. On the other hand, however, a solution having an excessive acid concentration, that is over 10 g/l for example, does not exhibit sufficient dissolution power. Solutions having excessively high or low acid concentration should be excluded.
• the third component the compounds which serve to suppress the decomposition of hydrogen peroxide, are (a) alcohol polyoxyethylene ether, (b) alkylsulfonic acid, (c) alkyl hydrogen phosphate, (cl) alkyl hydrogen phosphite, (e) alkyl hydrogen sulfate and their salts, and they are represented by the formulae as follows.
• R is an aliphatic hydrocarbon residue having 4 to 20 carbon atoms and n is an integer of 2 to 20;
• R is an alkyl group having 2 to 18 carbon atoms
• X is hydrogen or an alkyl group having 1 to 18 carbon atoms.
• R and R are the same as R and R respec tively in the above alkyl hydrogen phosphate
• R OSO I-l wherein R is the same as R in the above alkyl hydrogen phosphate.
• the concentration of above alcohol polyoxyethylene ether to be added is preferably 0.01 to 20 g/l, and if the concentration is within this range, the following effects that have been already mentioned could be achieved; (1) stabilization of hydrogen peroxide, (2) prevention of mist of the acid from spraying, (3) accelerated rate of dissolution of metals and producing luster on the finished surface.
• the most preferred concentration is 0.1 to g/l.
• Ethers (a) are featured by their high surface activity. Since they are nonionic, they form a stable and dense layer of foam on the surface of solutions for dissolution treatment even in the presence of acids and metal salts, serving to prevent mist of acid from spraying.
• the concentration of alkylsulfonic acid (b) to be added is preferably 0.01 to 20 g/l, more preferably 0.1 to 15 g/l.
• the concentrations of alkyl hydrogen phosphate (c), alkyl hydrogen phosphite (d) and alkyl hydrogen sulfate (e) to be added are preferably 0.001 to 20'g/l, more preferably 0.01 to 5 g/l.
• the alkyl hydrogen'phosphate (c), alkyl hydrogen phosphite (d) and alkyl hydrogen sulfate (e) are chemically more stable when alkyl groups are composed of more carbon atoms. But these compounds having too many carbon atoms show less solubility. For this reason the number of carbon atoms is restricted to l to 12.
• Alcohol polyoxyethylene ethers in (a) appear in Nos. 2 through 15 in Table 2. These ethers are not single pure compounds, but the degree of polymerization n of each ether is distributed to some extent; therefore molecular formulae of the major components are shown in the table. Examination of the influence of molecular weight proves that the magnitude of molecular weight exhibits some difference in the effect of stabilization (NOS. 2 to 7). The ethers slhow remarkable effect on stabilization when added in a concentration exceeding 0.01 g/l (Nos. 8 to 14). Addition of the ether in a concentration of over 20 g/l is too expensive and wasteful. In No.
• R is oleyl group, which is an unsaturated aliphatic hydrocarbon residue
• a better effect on stabilization can be seen in comparison with that when lower alkyl alcohol, carboxylic acids, glycerine, sodium pyrophosphate and 8-oxyquinoline, which have been previously used, are added in the same concentration.
• Nos. 16 through 29 show results when alkyl sulfonic acids (b) are used. In these cases, the effect on stabilization depends on the molecular structure of the compounds and the concentration of the compounds, the situation being just the same as in the case of alcohol polyoxyethylene ether (a). The best result was observed with ethan sulfonic acid.
• Alkyl sulfonic acids (b) generally exhibit better effect on stabilization than alcohol polyoxyethylene ethers (a) above.
• the results obtained from the use of alkyl hydrogen phosphate (c) and alkyl hydrogen phosphite (d) are shown in NOS. 30 through 43.
• the stabilizing effect depends on the concentration of compounds added, number of carbon atoms in the respective alkyl groups and the molecular structure, but the number of alkyl groups has almost nothing to do with such effect.
• the best stabilizing effect was observed with dibutyl hydrogen phosphate (No. 38) and butyl dihydrogen phosphite (No. 42). In respect to the effect of the concentration of diethyl hydrogen phosphate on the stabilization (Nos.
• Nos. 44 through 54 are examples where alkyl hydrogen sulfates (e) are used.
• the compounds of this category have somewhat less stabilizing effect than phosphate (c) and phosphite (d), but larger effect than ethers (a) and sulfonic acids (b) when used in lower concentrations.
• a compound having a straight chain exhibits better effect than a compound having a branched chain (Nos. 49 and 51 Needless to say, even the latter compound having a branched chain is much more useful than conventional stabilizing agents.
• alkyl hydrogen sulfates of the present invention having the same alkyl group are much better with respect to stabilizing effect. This is apparent from comparisons of No. 44 with No. 55, No. 45 with No. 62, No. 49 with No. 58, and No. 51 with No. 59;
• the stabilizing agents to be used in the present invention exhibit better effect of stabilizing hydrogen peroxide when added in a lower concentration than conventional stabilizing agents.
• the effect of the stabilizing agents to be used in the present invention was investigated on accelerating the rate of dissolution of metals and reducing the interference of chloride ions with the dissolution.
• the stabilizing agents referred to above, the third component to be used in this invention, together with chloride ions were each added separately to an aqueous solution containing 100 g/l of sulfuric acid and 45 g/l of hydrogen peroxide, and the rate of dissolution of yellow brass plates (Cu Zn 65 35 by weight percent) was measured at a bath temperature of 20C.
• the rate of dissolution is shown in Table 4 in relative values against the basic figure of 100 for the rate obtained when neither stabilizing agent nor chloride ion was added.
• Alcohol polyoxyethyleneether (a) accelerates the dissolution more than twice as much as when no additives are used, as seen in No. 4 and No.
• alcohol polyoxyethylene ethers (a), alkyl sulfonic acids (b), alkyl hydrogen phosphates (c), alkyl hydrogen phosphites (d) and alkyl hydrogen sulfates (e).
• alcohol polyoxyethylene ethers (a) are used in combination with acompound selected from the four groups of compounds (b), (c), (d) and (e)
• three major drawbacks inherent in conventional solutions for chemical dissolution treatment of metals could be readily avoided; that is (l) decomposition of hydrogen peroxide, (2) spraying of mist of acid and (3) decrease in dissolution rate of metals.
• alkyl sulfonic acids (b) and alkyl hydrogen phosphates (c) show little accelerating action toward dissolution of metals, but exhibit considerably large effect in reducing the interference of chloride ions with dissolution rate.
• the third component of this invention not only accelerates dissolution of metals, but also eliminates the interference of chloride ions, present in city water and other water, with dissolution of metals, which has been the fatal drawback of solutions for chemical dissolution which has been the.
• the third component to be used in the present invention may be at least one compound se* lected from the five groups of compounds mentioned
• red stain may often be generated at the contact area of the materials. Red stain is a result of dezincfication peculiar to yellow brass materials by which the surface partly assumes copper color. This phenomenon may very often happen when the materials are kept immersed for a long time in an unstirred bath which is lacking in hydrogen peroxide. This is the fourth drawback occurring in conventional solutions for chemical dissolution treatment.
• the fourth drawback of conventional solutions could be eliminated, according to the investigation of this invention, by adding 0.1 to 5,000 ppm, preferably 1 to 500 ppm, of glue or gelatine as the fourth component. Since glue and gelatine are subject to hydrolysis to some extent while in use, it may be possible to use partly hydrolyzed glue or gelatine (hydrolyzates). The theory of the function of these added matters is not evident. But, if the red stain is generated following the dissolution-deposition theory. it is considered that they function to suppress the deposition reaction of copper.
• the solutions for chemical treatment of metallic materials can be utilized for treatments of various metallic materials: pickling, etching, chemical milling and chemical polishing.
• metals include copper, silver, nickel, iron, zinc, aluminum, titanium and the alloys thereof, such as brass, nickelsilver, cupronickel and copper-titanium alloys.
• the present invention exhibits the best results.
• pickling is suited to a relatively low concentration (0.1 to 100 g/l) of hydrogen peroxide, while etching and chemical milling are suited to a relatively high concentration to 200 g/l) of hydrogen peroxide.
• Chemical polishing is performed by immersing materials to be treated in a specially concentrated solution to 300 g/l) for a short time, where the following procedure is particularly desired for copper and copper alloys: in a solution of this invention in which the concentration of hydrogen peroxide exceeds 5 g/l and the ratio .by weight of hydrogen peroxide to hydrogen ion concentration, H O /[H is over 30, copper or a copper alloy is immersed to form a colored coating film of oxide, and then immersed in a solution which dissolves the copper oxide such as solutions of dilute acids, ammonia, aminocarboxylic acid and sodium cyanide, to dissolve the colored coating film of oxide.
• Comparison 2 tained in the solution.
• the oxide scale remained in 5 min., but disappeared in 10 min. Although deposition of tiny powder of copper was not observed, the surface was not lustrous.
• EXAMPLE 2 The same wire rod as in Example 1 was immersed in a solution prepared with city water and having the following composition:
• EXAMPLE 3 The same wire rod was immersed in the same solu tion as in Example 2 except that 0.5 cc/l of ethyl hydrogen sulfate was further contained in the solution. The black scale disappeared in 5 min. and the surface obtained was semi-lustrous without deposition of tiny powder of copper.
• EXAMPLE 4 A copper-titanium alloy strip containing 4 percent by weight of titanium was heated for 7 min. in the air at 850C and quickly cooled to make it soft, when a primary scale of black copper oxide as major constituent and an approximately 4p. thick light brown sub-scale which resulted from internal oxidation of titanium were formed. The former scale was removed when cooled quickly.
• the copper strip having the sub-scale was immersed for 2 min. in the solution having the following composition:
• the metal was conventionally treated using a mixed aqueous solution containing sulfuric acid and sodium dichromate, where treatments of the waste solution containing harmful hexavalent chromium ions caused a serious problem with respect to pollution. Further the dissolved copper could not be recovered because a large amount of chromium coexisted in the solution.
• the waste solution was easily cleaned by neutralization with alkali, and then copper in the solution could be recovered by means of electrolysis from the waste solution.
• EXAMPLE 5 A yellow brass strip (Zn 35 wt. percent) was heat treated at 550C in an atmosphere of Kerosene decomposition gas for 1 hour and yellow brown oxide scale was formed. Almost all of the scale consisted of zinc oxide and there existed a thin layer caused by dezincfication 1 p.) on the surface of alloy in contact with the scale.
• the strip was immersed for 15 sec. in the solution of the following composition and a bright surface of yellow brass was obtained.
• EXAMPLE 6 Twenty cartridge brass tubes (Zn 30 percent) of 1 inch in outer diameter, that had been treated in the same atmosphere as in Example 5, were made into a bundle and hung with a copper wire in the solution having the following composition for min,:
• EXAMPLE 8 The same sheet as in Example 7 was immersed for 30 sec. in a solution of the following composition:
• EXAMPLE 9 A yellow brass sheet (Zn 35 wt. percent) was immersed for 3 min. in an aqueous solution at room temperature (20C) containing 5 g/l of alcohol polyoxyethylene ether, where C H O(C H O) H was the main constituent, and hydrogen peroxide and sulfuric acid were adjusted as shown in Table 5 (first stage of operation). The sheet was then immersed for 5 sec. in a dilute solution of sulfuric acid (3 percent) (second stage of operation), and dried after being washed with water.
• a pure copper sheet was immersed for l min. in a solution of the following composition:
• EXAMPLE 1 1 To etch a pure nickel sheet, the sheet was kept immersed in a solution of the following composition under stirring and the rate of dissolution was measured.
• EXAMPLE 12 A low-carbon steel sheet produced a bright surface when it was immersed for 30 sec. in a solution of the following composition:
• EXAMPLE 1 3 In preparing a titanium wire to be used as electrode for electrolysis, a'titanium wire carrying oxide scale was drawn to 2.0 mm diameter, then immersed for 30 min. in a molten caustic soda bath at 420C, and finally cooled quickly in water to remove the thick scale. The wire with a thin oxide film on the surface was immersed for 30 sec, in a solution of the following composition:
• Bath temperature about 20C The product had a coarse surface, which was desirable for use as electrode material.
• EXAMPLE 14 thick scale. Subsequently, the wire was immersed for 3 min. in a solution having the following composition. The surface of the wire became smooth and lustrous.
• a solution for the chemical dissolution treatment of metal materials comprising water, 0.1 to 10 g/l in bydrogen-ion concentration of an acid, 0.1 300 g/l of hydrogen peroxide and 0.001 20 g/l of at least one compound selected from the group consisting of a. an alcohol polyoxyethylene ether represented by the formula 0. an alkyl hydrogen phosphite represented by the formula and salts thereof,
• R is an aliphatic hydrocarbon residue having 4 to 20 carbon atoms
• n is an integer of 2 to 20
• R is an alkyl or hydroxyalkyl group, each having 1 to 12 carbon atoms
• R is hydrogen, or an alkyl or hydroxyalkyl group, each having 1 to 12. carbon atoms.
• R of the alcohol polyoxyethylene ether is an aliphatic hydrocarbon residue having 8 to 18 carbon atoms.
• R of the alcohol polyoxyethylene ether is an aliphatic hydrocar bon residue having 12 to 16 carbon atoms, and n is 6 to 12.
• R and R are normal chain alkyl groups, each having 2 to 8 carbon atoms.

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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)
• ing And Chemical Polishing (AREA)
• Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)

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• 1972
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