US3725217A - Plating titanium and zirconium and their alloys with nickel,chromium and other heavy metals - Google Patents

Plating titanium and zirconium and their alloys with nickel,chromium and other heavy metals Download PDF

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Publication number
US3725217A
US3725217A US00037843A US3725217DA US3725217A US 3725217 A US3725217 A US 3725217A US 00037843 A US00037843 A US 00037843A US 3725217D A US3725217D A US 3725217DA US 3725217 A US3725217 A US 3725217A
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Prior art keywords
titanium
zirconium
plating
fluoroborate
chromium
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US00037843A
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English (en)
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D Hartshorn
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MacDermid Enthone Inc
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IONITECH LABOR Inc
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Assigned to ENTHONE, INCORPORATED, WEST HAVEN, CT., A CORP. OF NEW YORK reassignment ENTHONE, INCORPORATED, WEST HAVEN, CT., A CORP. OF NEW YORK ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: IONITECH LABORATORIES, INC.
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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
    • C25D5/34—Pretreatment of metallic surfaces to be electroplated
    • C25D5/38—Pretreatment of metallic surfaces to be electroplated of refractory metals or nickel
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
    • C25D5/34—Pretreatment of metallic surfaces to be electroplated
    • C25D5/46—Pretreatment of metallic surfaces to be electroplated of actinides

Definitions

  • This invention relates to the plating of titanium and zirconium and their alloys with other metals, with heavy metals, especially chromium and nickel.
  • These metals are most difiicult to apply successfully to titanium and zirconium and may be regarded as a preferred species, to the plating of which upon titanium and zirconium the specification will be largely addressed. Titanium will be used as the exemplar in the description. Nonetheless the same process has had success in the application of gold, silver, iron, and copper plate to titanium and zirconium so that its use may be regarded as not limited to the more difficult metals; these metals may be applied by this method as a base for other plate.
  • Titanium alloys because of their excellent strengthweight ratio, superior corrosion resistance and ease of fabrication are finding increased application in the aircraft and aerospace industries. However, these applications are limited to uses which do not involve moving components such as bearing surfaces, sliding members and piston assemblies because of the inherent tendency of titanium and its alloys to seize or gall. Titanium metals are the most difficult of all metals to lubricate because of the nature of the adsorbed gas film on the metals surface. Another disadvantage is the tendency to adsorb nitrogen, oxygen and hydrogen at elevated temperatures, this adversely effecting their physical properties.
  • a primary object of the invention is to plate titanium or zirconium with chromium or nickel so that the plate will not peel, will have low friction, be dense and nonporous, resistant to high temperatures, be strongly adherent, and which will by standard test (Timken, so called) in the preferred mode be classified as of infinite life. Secondary objects of the inventions are to plate with less difficult metals to achieve superior adhesion.
  • cleaners are standard in heavy duty cleaning of metals, e.g., aqueous solutions of caustic soda plus sodium ortho or meta silicate, or plus sodium phosphate, or plus sodium carbonate, as a buffer. Ordinary cleaning takes 30 seconds to 15 minutes, the end point being freedom from oil, grease, and soil.
  • a typical pickle is 50% HNO 25% H 25% H O plus 1 lb./gal. of Actane (Actane 70 a fluoride type pickle additive).
  • Actane 70 a fluoride type pickle additive.
  • Some HP is formed by hydrolysis and bites into the titanium. This removes oxide, and some of the titanium if the treatment is prolonged. Assuming no scale, a dip of 1 minute or less is adequate. It takes longer if some scale exists. If the piece is badly scaled a sandblast should be used before the cleaning or before the pickle.
  • the pH of the sodium fluoroborate mixture is usually around 2. Agitation can be used.
  • the fluoroborate film is impervious and prevents reoxidation.
  • the fluoroborate coat is now to be attacked with a weak acid and the attack may proceed until the fluoroborate is invisible at magnification of 250x. Sometimes the electron microscope shows no film.
  • any aqueous acid solution can be used, examples of which are NaHSO citric acid; muriatic acid; and H 80 A concentration of 5% of mineral acid is adequate. 1 oz./ gal. of powdered acid or acid salts is often adequate. Any pH below 5 is usually adequate.
  • the process produces what is believed to be the first objects of titanium or zirconium, plated with nickel or chromium, in which firm adhesive is characteristic and reproducible, withstanding all tests including infinite life, the strength of the bond being such that when pieces are brazed or welded together, plate to plate, the pieces failed under tension before the plate.
  • the product is characterized by titanium or zirconium bodies electroplated with chromium or nickel in which a visible or invisible barrier of borofiuoride or silicofluoride (also called fluoroborates or fluorosilicates as salts derived from fiuoroboric or fluorosilicic acid) is interposed between body and plate.
  • a visible or invisible barrier of borofiuoride or silicofluoride also called fluoroborates or fluorosilicates as salts derived from fiuoroboric or fluorosilicic acid
  • the impervious barrier is applied as a conversion coating and the plate is applied electrolytically.
  • the use of silver fluoroborate has been proposed in the past but the manner of application was not the same and the results were not equivalent.
  • the invention forms an adherent titanium or zirconium conversion film on the metal by displacing the oxide layer on the surface and replacing it with a fluoroborate film which is largely or wholly removed by acid.
  • the fluoroborate film is made extremely thin, by a dip in acid, in some cases being invisible even under the electron microscope, while in other cases it constitutes a layer of visible thickness suggesting an intermediate coat between the plate and the titanium object. Chromium, nickel and other heavy metals, are then readily deposited by catalytic reduction, or by electroplating, on the titanium or zirconium from any of their conventional electroplating solutions.
  • a preferred fluoroborate solution consists of 4 to 6 oz./gal. of sodium fluoroborate in water containing 25% methyl carbitol.
  • the temperature of application of the fluoroborate should be between about 150 F. and about 200 F. in the preferred mode. Outside this range efiiciency is lowered and imperfections such as smut, use of excessive time, and areas of poor adhesion appear. Lower temperatures require longer time. Temperatures from F. to 210 F. have been used but the preferred range is recommended. Optimum temperature and time for the application of sodium fluoroborate solution to titanium articles is about 175 F. for about 4 to 6 minutes.
  • the optimum temperature is 140 F., the time required being about the same. Varying the time or temperature changes the thickness of the film of fluoroborate on the object. Thin films have advantages over thick films.
  • the fluoroborate solution is applied by immersion of the whole workpiece, but it can be applied to local areas when total coverage is not essential. Areas in which plating is not to be built up can be masked in accordance with hard chrome plating technique. Its application should be preceded by cleaning and pickling.
  • any standard metal cleaner can be used to prepare the metal for pickling but it is preferred to clean cathodically in an alkaline cleaner such as Enbond (Enthone), which may be used, as an illustration, at 8 to 12 oz./gal. at 180 F. for 2 minutes at 4 to 12 volts D.C. This treatment is followed by rinsing, and the cleaned object, after rinsing, should be immersed at once in the pickling bath. When such electrolytic cleaning is used the over-all process requires two electrolytic baths.
  • Enbond Enthone
  • the preferred pickling used in this invention is an acid treatment to remove oxide and scale. Sand or vapor blasting can be used to assist in this process in difiicult cases to loosen the oxide and scale.
  • a superior pickling bath is 25% H 80 50% HNO 25% H O (by volume) with one pound per gallon of Actane 70 (Enthone), which is a water soluble pickling additive.
  • the pickling bath should be uncontaminated by metals, such as Fe and Cu, which will deposit on the titanium or zirconium body.
  • a oneminute pickle at room temperature is adequate to eliminate surface etching unless scale or oxide is present, in which case a longer pickling is indicated.
  • Some contaminated baths can be made safe by adding chelate such as EDTA.
  • the titanous or zirconous object is transferred promptly to the fiuoroboron bath and rests there with or without agitation from about 4 to 6 minutes at about F., assuming about 4 oz./ gal. of sodium fluoroborate in water containing 25% methyl carbitol. It is withdrawn, rinsed in 8 02/ gal. NaHSO at room temperature for 5 minutes, rinsed in water, immersed in acid, and immersed in clean electrolyte of the metal being plated for 5 minutes at plating temperature. In plating with hard chromium the plating current need not be turned on until the workpiece is at bath temperature.
  • Any standard plating bath for the electrolytic deposition of chromium, nickel or the other heavy metals can be used. Their number is great and their compositions are described in the electroplating literature.
  • the object, with its conversion film of fluoroborate, is transferred quickly to the plating bath, and connected as cathode; it can be connected with the current on at plating density, or it can be connected before the current is turned on.
  • Plating continues until the desired thickness of plate has been deposited, whereupon the plated object is removed, cold rinsed, hot rinsed and dried.
  • the fluoroborate film is incredibly homogeneous. It is apparently a conversion coating. Its constitution is unknown but may correspond to a reaction between water, the fluoroborate ion, and titanium to produce a film of titanous salt. Difliculties of analysis and metallographic techniques have prevented verification of this theory, but electronmicrographs demonstrate an intimate bond.
  • Sodium fluoroborate is a preferred mode because of cost, availability, solubility, and consistent performance.
  • the barrier film should be formed at elevated temperature to secure maximum adherence and density. At the highest temperatures a dark smut may appear.
  • the smut may be prevented by reducing the ionization of the fluoroborate solution with inert additives. It was found that potassium or sodium nitrate, in concentrations of 1 to 16 oz./gal. for sodium nitrate, effectively slow down the reaction to form a more adherent conversion film with a minimum of smut. An excellent solution contained 6 oz./gal. NaNO and 6 oz./gal.
  • the preliminary method used for testing the adhesion of the electroplate was to process 1 x 4" x .040" strips and if the deposit was acceptable to the eye the strip was tightened in a vise and bent or broken with a hammer. This method is rapid and effective in obtaining comparative visual indications of adhesion. If a strip failed around the edges, or if peeling was observed around the bend and on the sides, the test was deemed a failure. When no peeling was observed in the area of the bend or break, the plating was considered so perfected as to require a more sophisticated method of testing; one widely used in the United States for evaluating solid film lubricants. It measures and records coefiicient of friction, speed, load in pounds per square inch and the time until failure.
  • EXAMPLE 1 The titanium rings were cleaned cathodically from 1 to minutes in Enbond cleaner 160 (Enthone) in an 8-12 oz./gal. aqueous solution at 180 F., cold rinsed in water, pickled for 2 minutes at room temperature in an aqueous solution containing 25% H 80 25% water, and 75% HNO and cold rinsed.
  • the rings were immersed for 4 minutes at 175 F. in an aqueous conditioning solution containing 6 oz./gal. of sodium nitrate and 6 oz./gal. of sodium fluoroborate. They were then rinsed in cold water and immediately immersed for 5 minutes in a 5% solution of HCl at 80 F. They were then cold rinsed and put into a standard nickel sulfamate plating bath as the cathode.
  • the current was turned on at a density of 72 amps/ft.
  • the fluoroborate film is apparently removed except for a very thin adherent coating and the adhesion of the plate is much improved. This can follow the sodium fiuoroborate treatment immediately or after the cold rinse. Electronmicrographs prove that this operation improves the adhesion materially and the tests indicate an improvement in adhesion as much as fourfold.
  • Copper and iron if present unavoidably, can often be deactivated in the baths by including a chelate such as EDTA.
  • the anodes in the plating bath can be inert such as carbon and platinum.
  • the deoxidizing solution used prior to plating may contain alkali metal or ammonium fluorosilicate, e.g. Na SiF in total or partial replacement of the fluoroborate.
  • concentration range of the fluorosilicate is from A to 5 oz./gal.
  • the current density employed will be different for different metals. For example, gold can be plated on titanium or zirconium by this process at current densities as low as 1 amp/ft. and chromium can be plated on titanium or zirconium at current densities as high as 500 amps/ftl
  • Other alkali metal nitrates are useful in place of sodium nitrate but have the disadvantages of higher costs and lesser solubility.
  • a method of plating upon a workpiece of titanium, zirconium, or their alloys with heavy metals which comprises cleaning and pickling the area of the workpiece to be plated, coating said area with a conversion coating by immersion in a solution of one of the group of compounds consisting of the alkali metal, ammonium, .alkaline earth, aluminum and magnesium flnoroborates and fiuorosilicates, and plating the coated area electrolytically as the cathode in a heavy metal electrolytic plating solution.
  • the fluoro solution contains a water soluble organic solvent of the class consisting of the alkyl carbitols, the Cellosolves, the alcohols.
  • a method of plating a workpiece of titanium, zirconium, or their alloys with other metals which comprises cleaning and pickling the area to be plated, displacing the oxide layer on the metal and forming a metal fluoroborate or fluorosilicate conversion film in its place, thinning the fiuoro film in an acid bath, and plating the workpiece from a heavy metal plating bath.
  • the method of preparing a titanium or zirconium object for plating with heavy metals which comprises cleaning and pickling the object, reacting the surface thereof with an aqueous alkali metal, or ammonium, fluoroborate solution, and thinning the fluoro film deposit in an acid bath.
  • a method of plating titanium, zirconium, and their alloys which comprises cleaning, pickling, forming an alkali metal or ammonium fluoroborate or fluorosilicate conversion coating, immersing the coated metal in acid, and plating electrolytically in a heavy metal plating bath.
  • Chromium plated titanium or zirconium metal having a thin conversion bonding layer of fluoroborate or fiuorosilicate between and attached to the titanium or zirconium metal and the chromium plate.
  • Nickel plated titanium or zirconium metal having References Cited UNITED STATES PATENTS 3,540,943 11/1970 Grogan 148--6.14R 3,472,742 10/1969 Webb 2O438 B 3,065,154 11/1962 Wiesner 204-51 JOHN H. MACK, Primary Examiner R. L. ANDREWS, Assistant Examiner US. Cl. X.R.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electroplating Methods And Accessories (AREA)
  • Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
  • Chemical Treatment Of Metals (AREA)
US00037843A 1969-07-18 1970-05-15 Plating titanium and zirconium and their alloys with nickel,chromium and other heavy metals Expired - Lifetime US3725217A (en)

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US84318569A 1969-07-18 1969-07-18
US3784370A 1970-05-15 1970-05-15

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US (1) US3725217A (enrdf_load_stackoverflow)
JP (1) JPS4913138B1 (enrdf_load_stackoverflow)
CA (1) CA943097A (enrdf_load_stackoverflow)
DE (1) DE2035659A1 (enrdf_load_stackoverflow)
FR (1) FR2051864B1 (enrdf_load_stackoverflow)
GB (1) GB1304905A (enrdf_load_stackoverflow)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4017368A (en) * 1974-11-11 1977-04-12 General Electric Company Process for electroplating zirconium alloys
US4093756A (en) * 1976-10-04 1978-06-06 General Electric Company Process for electroless deposition of metals on zirconium materials
US4902388A (en) * 1989-07-03 1990-02-20 United Technologies Corporation Method for electroplating nickel onto titanium alloys
US4938850A (en) * 1988-09-26 1990-07-03 Hughes Aircraft Company Method for plating on titanium
USRE33800E (en) * 1989-07-03 1992-01-21 United Technologies Corporation Method for electroplating nickel onto titanium alloys
US20090218232A1 (en) * 2005-11-21 2009-09-03 Mtu Aero Engines Gmbh Method for the Pre-Treatment of Titanium Components for the Subsequent Coating Thereof
US20130058791A1 (en) * 2011-09-02 2013-03-07 General Electric Company Protective coating for titanium last stage buckets

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3025845U (ja) * 1995-07-11 1996-06-25 富士男 河合 肩帯が伸縮物と面ファスナーで成るブラジャー

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2711364A (en) * 1953-12-31 1955-06-21 John G Beach Polishing metals and composition therefor

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4017368A (en) * 1974-11-11 1977-04-12 General Electric Company Process for electroplating zirconium alloys
US4093756A (en) * 1976-10-04 1978-06-06 General Electric Company Process for electroless deposition of metals on zirconium materials
US4938850A (en) * 1988-09-26 1990-07-03 Hughes Aircraft Company Method for plating on titanium
US4902388A (en) * 1989-07-03 1990-02-20 United Technologies Corporation Method for electroplating nickel onto titanium alloys
USRE33800E (en) * 1989-07-03 1992-01-21 United Technologies Corporation Method for electroplating nickel onto titanium alloys
US20090218232A1 (en) * 2005-11-21 2009-09-03 Mtu Aero Engines Gmbh Method for the Pre-Treatment of Titanium Components for the Subsequent Coating Thereof
US8354036B2 (en) * 2005-11-21 2013-01-15 Mtu Aero Engines Gmbh Method for the pre-treatment of titanium components for the subsequent coating thereof
US20130058791A1 (en) * 2011-09-02 2013-03-07 General Electric Company Protective coating for titanium last stage buckets
US9267218B2 (en) * 2011-09-02 2016-02-23 General Electric Company Protective coating for titanium last stage buckets
US10392717B2 (en) 2011-09-02 2019-08-27 General Electric Company Protective coating for titanium last stage buckets

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JPS4913138B1 (enrdf_load_stackoverflow) 1974-03-29
CA943097A (en) 1974-03-05
FR2051864A1 (enrdf_load_stackoverflow) 1971-04-09
FR2051864B1 (enrdf_load_stackoverflow) 1974-09-20
GB1304905A (enrdf_load_stackoverflow) 1973-01-31
DE2035659A1 (de) 1971-02-18

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Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:IONITECH LABORATORIES, INC.;REEL/FRAME:004492/0523

Effective date: 19851115