US3557000A - Alkali etchant composition for aluminum having extended bath life - Google Patents

Alkali etchant composition for aluminum having extended bath life Download PDF

Info

Publication number
US3557000A
US3557000A US769755A US3557000DA US3557000A US 3557000 A US3557000 A US 3557000A US 769755 A US769755 A US 769755A US 3557000D A US3557000D A US 3557000DA US 3557000 A US3557000 A US 3557000A
Authority
US
United States
Prior art keywords
aluminum
alkali
bath
etching
alkali metal
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
US769755A
Other languages
English (en)
Inventor
Harold Vernon Smith
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.)
Pennwalt Corp
Original Assignee
Pennwalt Corp
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 Pennwalt Corp filed Critical Pennwalt Corp
Application granted granted Critical
Publication of US3557000A publication Critical patent/US3557000A/en
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
    • 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
    • C23F1/32—Alkaline compositions
    • C23F1/36—Alkaline compositions for etching aluminium or alloys thereof

Definitions

  • An alkali etching composition for aluminum is comprised of an aqueous solution of alkali metal hydroxide, hexavalent chorium ion, chelating agent, and a minor pro portion of fluoroalkyl surfactant. The composition provides more eflicient alkali consumption and a longer bath life.
  • This invention pertains to compositions for the etching of aluminum and aluminum alloys. More particularly, this invention concerns an alkali composition which, as an aqueous alkali etching solution for aluminum, provides more efiicient alkali consumption and longer bath life due to the incorporation therein of a specifically defined minor proportion of fluoroalkyl surfactant.
  • Industrial aluminum finishers usually process their product in an aqueous alkaline etching bath to remove surface imperfections and generally to enhance the appearance of the aluminum or aluminum alloy product. In such operations it is desirable for obvious economic reasons to produce good finishes with the smallest possible consumption of etching chamicals while endeavoring to employ the etchant baths over an extended period of time without the need for frequent costly dumping and recharging.
  • the conventional, previously used, alkaline etching compositions suffer from deficiencies in these areas in the following respects.
  • Conventional alkaline etchant systems such as that disclosed in my US. Pat. 3,314,890, generally involve the removal of a relatively large amount of metal from the surface of the treated aluminum object to produce an acceptable finish.
  • the novel aqueous etching solution of this invention produces a desired architectural finish on aluminum and aluminum alloys that may be described as an etched finish, gray white to white in color, having a non-metallic appearance, having a low or matte reflectance, having a uniform fine grained appearance independent of any underlying aluminum grain boundaries and having what is known in the trade as an excellent hide, that is, all extrusion, die marks and scratches are completely hidden.
  • the etchant consumption is significantly reduced to the extent that there is about 10% to 25% less consumption of the etchant chemicals than that incurred using the conventional etching compositions to accomplish an equivalent amount of surface finishing.
  • the bath life is appreciably extended because the solution can be used without causing product surface defects until the specific gravity of the bath is increased by dissolved aluminum to a value of from about 1.35 to 1.50, compared to a specific gravity of 1.20 for the previously known baths at which point dumping would be required to avoid defective etching.
  • This invention provides an alkali etching composition for aluminum and aluminum alloys comprised of an aqueous solution containing (A) from 3.75 to 209 grams per liter of alkali metal hydroxide, (B) water-soluble hexavalent chromium ion ranging in amount of at least 0.035% by weight of the alkali metal hydroxide content and no greater than 11 grams per liter, (C) chelating agent ranging in amount of at least 3% by weight of the alkali metal hydroxide content and no greater than 44 grams per liter and (D) fluoroalkyl surface active agent ranging in amount of at least 0.0002% by wegiht of the alkali metal hydroxide content and up to 0.44 gram per liter.
  • A from 3.75 to 209 grams per liter of alkali metal hydroxide
  • B water-soluble hexavalent chromium ion ranging in amount of at least 0.035% by weight of the alkali metal hydroxide content and no greater than 11 grams
  • an embodiment of the invention comprises the solid granular compositions which are capable of forming the foregoing aqueous solutions by mixing in water.
  • the components are present in the following ranges in percents by weight: (A) from 80% to 95% of alkali metal hydroxide, (B) from 0.035% to 5% of water-soluble hexavalent chromium, (C) from 3% to 20% of chelating agent, and (D) from 0.0002% to 0.2% of fluoroalkyl surfactant, said percentages of (B), (C) and (D) based on the weight of the alkali metal hydroxide (A).
  • the total of the four components will, of course, be 100%.
  • the composition of this invention can also be conveniently handled as a liquid concentrate comprised of from 15 to 60 weight percent of the aforesaid granular composition and from 40 to weight percent water.
  • Sodium hydroxide is the principal source of the alkali metal hydroxide because it is inexpensive as compared to potassium or lithium hydroxide. However, potassium hydroxide or other alkali metal hydroxides are equally efficient in these compositions.
  • the source materials for the hexavalent chromium ion are one or more of the wellknown water-soluble ionizable chromium containing compounds. They may beselected from the group which includes sodium dichromate, potassium dichromate, ammonium dichromate, sodium chromate, potassium chromate, chromic anhydride, sodium chrom glucosate and potassium chrom glucosate.
  • the above sources of hexavalent chromium ion are all normally solid materials and of course are useful in preparing the solid granular concentrates which are used in making the etching solutions.
  • the third component of the formulation which acts as a surface modifier with respect to the action of the alkali metal hydroxide etchant on aluminum and aluminum al-v loys is a special group of Wellknown surface modifyingg agents of the chelating type which combine with the hexavalent chromium to modify the attack of the caustic soda and to prevent precipitation of aluminum salts from solution.
  • Suitable chelating agents include sorbital, mannitol, ascorbic acid, sorbose, tannic acid, ethylene diaminetetraacetic acid, diglycolic acid, picolinic acid, aspartic acid, dithiooxamide, l-rhamnose, b-fructose, glycerol, maleic acid, mannose, succinic acid, sucrose, tartaric acid and the like.
  • R is an alkylene group and R is hydrogen or alkyl; the acids and salts of U.S. 2,951,051, i.e.,
  • the aluminum or aluminum alloy is first cleaned with a conventional aluminum cleaner which may be of the alkaline or acid type to remove oxides and soil which might obstruct the etching action.
  • a conventional aluminum cleaner which may be of the alkaline or acid type to remove oxides and soil which might obstruct the etching action.
  • the aluminum is rinsed with water, preferably warm, and is then immersed in or sprayed with the etching solution held at a temperature within the range of 150 to 200 F. However, at temperatures less than 150 F. the solutions are effective in preventing the unwanted effect known in the industry as galvanizing.
  • the preferred temperature range for securing the preferred architectural finish is within the range of 160 to 180 F.
  • the metal workpiece is allowed to remain in contact with the etchant solution until the desired etch is obtained. Generally this will vary from one to minutes depending on the concentration of the ingredients in the bath and the temperatures used. Suitable etching is often obtained in about 3 to 7 minutes.
  • the work piece is then rinsed at least once with water, preferably warm, and then the work piece is desmutted to remove the metal particles which are insoluble in the etching solution. Since the present etching solutions have a considerable concentration of chromium contained therein it is unnecessary to use a chromated desmutter, and in fact, a nonchromated desmutter is preferred.
  • tEtchant baths were prepared having the following compositions wherein the proportions are expressed in grams of ingredient per liter of aqueous solution and in weight percent based on a dry composition basis.
  • a Bath B type composition was used for two weeks with appropriate replenishment before an unacceptable increase in viscosity and lack of etching efficiency required its disposal.
  • a Bath C composition was used for some nine weeks with appropriate replenishment before disposal became necessary.
  • a composition for the etching of aluminum and aluminum alloys comprised of an aqueous solution of (A) from 3.75 to 209 grams per liter of alkali metal hydroxide, (B) water-soluble hexavalent chromium ion ranging in amount of at least 0.035% by weight of the alkali metal hydroxide and up to 11 grams per liter, (C) chelating agent ranging in amount of at least 3% by weight of the alkali metal hydroxide and up to 44 grams per liter and (D) fluoroalkyl surfactant ranging in amount of at least 0.0002% by weight of the alkali metal hydroxide and up to 0.44 gramper liter.
  • the solid granular composition capable of forming References Cited the aqueous etching solution of claim 1 comprised of (A) UNITED STATES PATENTS from 80% to 95% of alkali metal hydroxide, (B) from 0.002% to 0.2% of fluoroalkyl surfactant, hte precent- 3314890 4/1967 Smlth (C) from 3% to 20% Of chelating agent and (D) from 5 JACOB H STEINBERG i E i 0.0002% to 002% of fluoroalkyl surfactant, the percentages of (B), (C) and (D) being based on the Weight of US. Cl. XJR.

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)
  • ing And Chemical Polishing (AREA)
  • Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
US769755A 1968-10-22 1968-10-22 Alkali etchant composition for aluminum having extended bath life Expired - Lifetime US3557000A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US76975568A 1968-10-22 1968-10-22

Publications (1)

Publication Number Publication Date
US3557000A true US3557000A (en) 1971-01-19

Family

ID=25086410

Family Applications (1)

Application Number Title Priority Date Filing Date
US769755A Expired - Lifetime US3557000A (en) 1968-10-22 1968-10-22 Alkali etchant composition for aluminum having extended bath life

Country Status (8)

Country Link
US (1) US3557000A (enrdf_load_stackoverflow)
JP (1) JPS4843020B1 (enrdf_load_stackoverflow)
BE (1) BE740553A (enrdf_load_stackoverflow)
CH (1) CH508739A (enrdf_load_stackoverflow)
DE (1) DE1952425C3 (enrdf_load_stackoverflow)
FR (1) FR2021214A1 (enrdf_load_stackoverflow)
GB (1) GB1227070A (enrdf_load_stackoverflow)
NL (1) NL6915915A (enrdf_load_stackoverflow)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4028205A (en) * 1975-09-29 1977-06-07 Kaiser Aluminum & Chemical Corporation Surface treatment of aluminum
US4477290A (en) * 1983-01-10 1984-10-16 Pennwalt Corporation Cleaning and etching process for aluminum containers
US4588474A (en) * 1981-02-03 1986-05-13 Chem-Tronics, Incorporated Chemical milling processes and etchants therefor
US4915782A (en) * 1988-12-21 1990-04-10 Mcdonnell Douglas Corporation Aluminum lithium etchant
US5186790A (en) * 1990-11-13 1993-02-16 Aluminum Company Of America Chemical milling of aluminum-lithium alloys
US5700383A (en) * 1995-12-21 1997-12-23 Intel Corporation Slurries and methods for chemical mechanical polish of aluminum and titanium aluminide

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111593349B (zh) * 2020-06-03 2022-03-04 江苏富乐华半导体科技股份有限公司 一种用于制备超薄钛箔的化学铣切液及铣切方法

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4028205A (en) * 1975-09-29 1977-06-07 Kaiser Aluminum & Chemical Corporation Surface treatment of aluminum
US4588474A (en) * 1981-02-03 1986-05-13 Chem-Tronics, Incorporated Chemical milling processes and etchants therefor
US4477290A (en) * 1983-01-10 1984-10-16 Pennwalt Corporation Cleaning and etching process for aluminum containers
US4915782A (en) * 1988-12-21 1990-04-10 Mcdonnell Douglas Corporation Aluminum lithium etchant
US5186790A (en) * 1990-11-13 1993-02-16 Aluminum Company Of America Chemical milling of aluminum-lithium alloys
US5700383A (en) * 1995-12-21 1997-12-23 Intel Corporation Slurries and methods for chemical mechanical polish of aluminum and titanium aluminide

Also Published As

Publication number Publication date
FR2021214A1 (enrdf_load_stackoverflow) 1970-07-17
NL6915915A (enrdf_load_stackoverflow) 1970-04-24
JPS4843020B1 (enrdf_load_stackoverflow) 1973-12-15
BE740553A (enrdf_load_stackoverflow) 1970-04-21
DE1952425A1 (de) 1970-04-30
GB1227070A (enrdf_load_stackoverflow) 1971-03-31
CH508739A (fr) 1971-06-15
DE1952425B2 (de) 1978-10-19
DE1952425C3 (de) 1979-06-21

Similar Documents

Publication Publication Date Title
US4886616A (en) Aluminum surface cleaning agent
US3864139A (en) Pretreatment compositions and use thereof in treating metal surfaces
US4370177A (en) Coating solution for metal surfaces
US4578122A (en) Non-peroxide trivalent chromium passivate composition and process
US3409522A (en) Electrochemical machining of titanium and alloys thereof
KR860003853A (ko) 알카리성 세정방법
US3557000A (en) Alkali etchant composition for aluminum having extended bath life
US2494910A (en) Method of and composition for coating aluminum
US5362317A (en) Sealant compositions and process for sealing aluminum oxide films
US5269957A (en) Rust removing agent for stainless steel surface
US2702768A (en) Ferrous surface coating process using alkali metal phosphates and hydroxylamines
US3113051A (en) Process and composition for producing aluminum surface conversion coatings
US2846343A (en) Product and method for effecting a cold chemical oxidation of aluminum and its alloys
US2750337A (en) Electroplating of chromium
DE2328763C2 (de) Wässriges alkalisches borathaltiges Reinigungsmittel und Verfahren zu seiner Herstellung
US2939772A (en) Process for etching aluminum and aluminum alloy surfaces
US3447972A (en) Process and compositions for producing aluminum surface conversion coatings
US2887418A (en) Composition for and method of chrome pickling of magnesium shapes
US2581490A (en) Electrolytic process of stripping metallic coatings from a ferrous metal base
US3887405A (en) Method and composition for cleaning copper surfaces
US2975039A (en) Chemical composition and process for aluminum etching
US3018211A (en) Composition and process for brightening aluminum and its alloys
US3362911A (en) Chromic acid-sulfuric acid solutions containing chloride catalyst for dissolving metals
US2724668A (en) Combination cleaning and coating solution for metallic surfaces and method of forming coatings therewith
US2796372A (en) Corrosion protecting metal finishing composition