US2886451A - Processes of regenerating chemical nickel plating solutions - Google Patents

Processes of regenerating chemical nickel plating solutions Download PDF

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Publication number
US2886451A
US2886451A US709622A US70962258A US2886451A US 2886451 A US2886451 A US 2886451A US 709622 A US709622 A US 709622A US 70962258 A US70962258 A US 70962258A US 2886451 A US2886451 A US 2886451A
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nickel
phosphite
anions
calcium
plating solution
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US709622A
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English (en)
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Budininkas Pranas
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General American Transportation Corp
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Gen Am Transport
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Priority to US709622A priority Critical patent/US2886451A/en
Priority to CH6638358A priority patent/CH381047A/fr
Priority to BE573175A priority patent/BE573175A/fr
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    • 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
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
    • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
    • C23C18/31—Coating with metals
    • C23C18/32—Coating with nickel, cobalt or mixtures thereof with phosphorus or boron
    • C23C18/34—Coating with nickel, cobalt or mixtures thereof with phosphorus or boron using reducing agents
    • C23C18/36—Coating with nickel, cobalt or mixtures thereof with phosphorus or boron using reducing agents using hypophosphites
    • 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
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
    • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
    • C23C18/1601—Process or apparatus
    • C23C18/1617—Purification and regeneration of coating baths

Definitions

  • the present invention relates to processes of regenerating aqueous chemical nickel plating solutions of the nickel cation-hypophosphite anion type, and particularly to such plating solutions employed in continuous nickel plating systems of the general character of that disclosed in U.S. Patent No. 2,717,218, granted on September 6, 1955, to Paul Talmey and William J. Crehan.
  • a chemical nickel plating solution of this type essentially comprises an aqueous solution of nickel cations and hypophosphite anions, the nickel cations being derived from nickel sulfate, nickel chloride, nickel hypophosphite, etc., and the hypophosphite anions being derived from hypophosphorous acid, sodium hypophosphite, potassium hypophosphite, nickel hypophosphite, etc.
  • a plating solution comprises an absolute concentration of hypophosphite anions within the range 0.15 to 1.20 moles/liter, a ratio between nickel cations and hypophosphite anions expressed in molar concentrations within the range 0.25 to 1.60, and a pH in the range 4.5 to 11.
  • the plating solution disclosed in the Gutzeit, Talmey and Lee application Serial No. 569,815 is particularly advantageous andcomprises, in addition to the nickel cations and the hypophcsphite anions, lactic anions and propionic anions, and having a pH in the acid range 4.4 to 5.6; and specifically this plating bath comprises an absolute concentration of hypophosphite anions within the range 0.15 to 1.20 moles/liter, a ratio between nickel cations and hypophosphite anions expressed in molar concentrations within the range 0.25 to 1.60, an absolute concentration of lacticY anions within the range 0.25 to 0.60 mole/ liter and an absolute concentration or" propionie ions within the range 0.025 to 0.060.
  • a typical plating solution of'this type has the following composition:
  • the nickel reduc-v tion-hypophosphite oxidation reaction proceeds, the nickel cations and hypophosphite ⁇ anions are depleted with the formation of hydrogen ions; and in order to preserve substantially the initial composition of the plating solution, the same is partially regenerated, either periodically or continuously, by the addition of nickel cations, hypophosphite anions and hydroxyl anions; however, as this partial regeneration proceeds, there is a build-up in the plating solution of phosphite anions, the anions of the nickel salt employed and the cations of the hypophosphite employed.
  • the build-up of substantial phosphite anions in the plating solution is particularly undesirable, since ultimately nickel phosphite will be precipitated therein, the tolerance of the plating solution to the presence of phosphite anions therein being dependent upon the particular composition of the plating solution, the plating solution of the composition specified above having a phosphite anion tolerance in excess of about one molar.
  • Gutzeit and Metheny is very advantageous in View of the fact that a regenerated chemical plating solution is brought back substantially to the initial composition thereof with no resulting build-up therein of phosphite anions, and the other ions mentioned.
  • the depleted chemical nickel plating solution is first contacted by a cation exchange resin, sofas to bring about the extraction therefrom of the nickel cations; then the euent is subjected to calcium hydroxide treatment, wherein the pH of the solution is increased well into the base range bringing about the precipitation of calcium phosphite.
  • the resulting solution is then filtered to remove the precipitated calcium ⁇ phosphite therein; and the filtrate is cooled to a temperature within the general range 0 C. to 5 C., bringing about the crystallization therein of sodium sulfate.
  • This solution is then filtered to remove the sodium sulfate therefrom; and the resulting filtrate is reconstituted by the addition thereto of nickel sulfate, sodium hypophosphite and sulfuric acid.
  • Another object of the invention is to provide an improved process of removing phosphite anions from a depleted chemical nickel plating solution of the type' noted, without the prior removal of nickel cations from This process of Talmey, ⁇
  • a still further object of the invention is to provide an improved process of regenerating completely a chemical nickel plating solution of the nickel cation-hypophosphite anion type that is simple and economical to carry out.
  • the filtrate is treated with a composite aqueous slurry of calcium sulfate (gypsum) and calcium hydroxide, theltrate in the tank 13 being agitated, and the addition of the calcium hydroxide being controlled so that the pH thereof is elevated into the general range 5.5 to 6.0; and particularly the pH is maintained below 7.0, so as positively to prevent the precipitation therein of nickel phosphite.
  • calcium phosphite is precipitated, without any substantial precipitation ot calcium hypophosphite or any nickel salt.
  • the total addition of calcium ion is at least less than the stoichiometric amount thereof required'to precipitate all of the phosphite anions in order to avoid the presence of calcium ions in the regenerated plating solution.
  • the resulting suspension is delivered to an associated iilter 14, whereby the calcium phosphite is separated therefrom, and the resulting ltrate is delivered to an associated tank 15.
  • Figure l is a diagrammatic illustration of the steps involved in the complete regeneration of a chemical nickel plating solution of the nickel cation-hypophosphite anion type, in accordance with the process of the present invention.
  • Fig. 2 is a diagrammatic illustration of a continuous nickel plating system in which the plating solution mentioned may be employed.
  • the present invention is predicated upon the discovery that in a depleted aqueous chemical nickel plating solu-j tion of the nickel cation-hypophosphite anion type, the undesirable phosphite anions may be selectively precipitated in the presence of the desirable nickel cations and hypophospbite anions, without the coprecipitation of either the nickel cations or the hypophosphite anions, by alkaline earth cations, when the pH of the solution is properly controlled and maintained within the range 5.5 to 7.0, during the precipitation of the alkaline earth phosphite. ln accordance with the arrangement, the required alkaline earth cations are supplied jointly by the corresponding soluble salt and by the corresponding hydroxide.
  • the plating solution is initially composed employing nickel sulfate and sodium hypophosphite
  • calcium may be advantageously employed, the salt4 (calciurn sulfate) and the hydroxide (calcium hydroxide) being employed jointly to supply the required calcium cations and to obtain the desired pH.
  • a depleted aqueous chemical nickel plating solution of the nickel cation-hypophosphite anion type, derived from a continuous plating system may essentially comprise:
  • the iiltrate delivered to the tank 17 contains substantially all of the nickel cations and all of the hypophosphite anions of the initial depleted plating solution, aside from certain small losses that are substantially entirely mechanical in character; however, this filtrate contains only about 10% to 25% of the phosphite anion concentration of the initial depleted plating solution, which phosphite anion content is in no way objectionable. Moreover, during the treatment, there is substantially no loss from the initial depleted plating so.
  • the filtrate is reconstituted by the addition thereto of ynickel sulfate, sodium hypophosphite andy sulfuric acid, together with sodium hydroxide, to obtain the desired pH of about 4.7 in this illustrative bath. Also, small additions of lactic acid and propionic acid are made in order to reconstitute the platin-g bath with respect to these ingredients. At this time, the regenerated plating solution has substantially the composition of the initially formulated plating solution and is returned to the continuous plating system for further plating use.
  • the calcium hydroxide is employed in conjunction with the calcium sulfate so as to provide substantially the required amount of calcium ions to precipitate the calcium phosphite, and to bring the solution to the optimum pH range, as noted above.
  • a by-pass 18 is illustrated that extends directly from the filter 14 to the tank 17.
  • a valve 19a is arranged in the by-pass 18, and a valve 19b is arranged in the direct conduit -to the tank 15, so that all, or any part, of the ltrate from the til-ter 14 may be diverted directly to the tank 17.
  • a conventional continuous chemical nickel plating system is diagrammatically illustrated as comprising a regeneration tank 21, a storage tank 22, a heater 23, a plating tank 24, and a cooler 25, arranged in tandem relation in the order named, together with a pump 27 and a lter 28 arranged in series relation between the storage tank 22 and the heater 23, and a.
  • the plating solution is lregenerated in the regeneration tank 21 (which may correspond in ⁇ fact to the tank 17 described in conjunction kwith Fig. l), and while the plating Asolution is cool and at a temperature of about 60 C.
  • the plating solution is delivered to the storage tank 22, from Which-it is pumped by the pump 27 through the filter 28 and thence through the heater 23 and delivered to the plating tank 24.
  • the-plating solution is heated tofan effective plating temperature in the general range 85 C. to 95 C.
  • the plating solution is-pumped by the pump 29 through the cooler 25 and returned to the regeneration tank 21.
  • the plating solution is cooled so that the temperature thereof is returned substantially back to about 60 C., prior to the return of the plating solution to the regeneration tank 21.
  • the work-pieces to be plated are immersed in the ⁇ plating solution in the plating tank 24 inthe usual manner; which work-pieces must necessarily have a catalyticsurface so that the plating reaction may proceed.
  • thecatalytic elements are: cobalt, nickel, palladium, rhodium and ruthenium. VHowever, alarge group of other elements can be rendered catalytic, either by displacement orrby galvanic Ainitiation in the -plating solution, so that the autocatalytic plating reaction may proceed.
  • This group of elements includes aluminum, carbon, copper, iron, magnesium, titanium and uranium (as Well as silver and gold), and the various alloys thereof. Also, insulators can be satisfactorily nickel plated when the surfaces thereof are suitably activated Iwith one of the ⁇ catalytic elements named.
  • aplating solution that has been regenerated in accordance With fthe present lprocess is equally effective as an initially composed plating solution in the production of bright, smooth coatings upon thework-pieces, that are intimately bonded thereto, and with a high plating rate.
  • the plating rate is normally in the range of 0.9 to 1.0 mil/hour of nickel plating upon the Iwork-pieces.
  • the whole body of plating solution may be regenerated after several passes thereof through the system, or a fractional part thereof may be by-passed continuously from the cooler 25 to the regeneration equipment, followed by the present treatment and then the return thereof to the regeneration tank 21.
  • the Vfollowing procedure is illustrative of repeated regenerations of an aqueous 'chemical nickel plating solution of the Vnickel cation-hypophosphite anion type. Specifically, an initial plating solution of this type was provided and after utilization thereof in the continuous plating system, it became depleted, at which time it had the following composition with respect to the important lons:
  • This depleted plating solution was regenerated in accordance with the previously described process; whereby it was first cooled to a temperature of 5 C. to elfect the crystallization of sodium sulfate therein. The solution was then ltered to remove the sodium sulfate; and thereafter to the filtrate there was added an aqueous slurry of 0.35 m./l. CaSO.1.1/2H2O and 0.65 m./1. Ca(OH)2, so as to effect the precipitation of calcium phosphite therein. The suspension was then filtered to remove the precipitated calcium phosphite therefrom;
  • This depleted plating solution was regenerated in-ac cordance -with Ithe previously described process; whereby it was rs ⁇ t cooledto'atemperature:of.5C. to effect 'the crystallization of sodium sulfate therein.
  • the suspension was then'ltered to remove ⁇ the sodium sulfate; and therea'fter to vthe filtrate there was added an aqueous slurry "of 0.35 m./l. :of CaSO4.1/2H2O and 0.65 ⁇ m./l. CaO, so vas to eiect'the precipitation of calcium phosphite therein.
  • the suspension was then filtered to remove the .precipitated calcium :phosphite therefrom; and to the filtrate there was added 0.04 m./l. of NaF, so as vto effect the vprecipitation of calcium fluoride therein.
  • the suspension was then iiltered'to remove lthe. precipitated y.calcium fluoride therefrom; whereby the filtrate had the following -composition with .respect to theimportantions:
  • Ni+ H2PO2- HP O3- s O4"- Ca++ Negligible employed; whereas in the second case, calcium oxide was employed; and it will be understood that the utilization of these two compounds is interchangeable, as each provides calcium cations and effects the desired increase in the pH of the solution. Further it is mentioned that inthe second regeneration set forth, sodium fluoride was employed in order to remove the residual calcium cations, as calcium fluoride, as previously explained.
  • the plating solution may be initially composed utilizing nickel chloride and sodium hypophosphite;
  • the alkaline earth salt may be barium sulfate, barium chloride, etc., strontium sulfate, strontium chloride, etc., as well as calcium sulfate, calcium chloride, etc.; and likewise, the alkaline earth hydroxide may be barium hydroxide, strontium hydroxide or calcium hydroxide.
  • alkaline earth salt is calcium salt.
  • said alkaline earth salt is calcium sulfate.

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  • Chemical & Material Sciences (AREA)
  • General Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Chemically Coating (AREA)
  • Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)
US709622A 1958-01-17 1958-01-17 Processes of regenerating chemical nickel plating solutions Expired - Lifetime US2886451A (en)

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US709622A US2886451A (en) 1958-01-17 1958-01-17 Processes of regenerating chemical nickel plating solutions
CH6638358A CH381047A (fr) 1958-01-17 1958-11-20 Procédé de régénération d'un bain aqueux de nickelage chimique
BE573175A BE573175A (fr) 1958-01-17 1958-11-20 Perfectionnements aux procédés de nickelage chimique.

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2983634A (en) * 1958-05-13 1961-05-09 Gen Am Transport Chemical nickel plating of magnesium and its alloys
US2993810A (en) * 1959-03-30 1961-07-25 Douglas Aircraft Co Inc Bath and process for chemically nickel plating magnesium
US3325297A (en) * 1956-04-09 1967-06-13 Gen Am Transport Processes of continuous chemical nickel plating
US3340073A (en) * 1961-05-27 1967-09-05 Bayer Ag Regeneration of chemical plating baths
US4038085A (en) * 1976-03-03 1977-07-26 Chromium Industries, Inc. Method of treating electroless nickel plating bath
WO1999039023A3 (fr) * 1998-01-31 1999-09-23 Lea Associates Limited Ameliorations apportees a un nickelage chimique

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2726968A (en) * 1953-12-03 1955-12-13 Gen Motors Corp Electroless nickel solution control

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2726968A (en) * 1953-12-03 1955-12-13 Gen Motors Corp Electroless nickel solution control

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3325297A (en) * 1956-04-09 1967-06-13 Gen Am Transport Processes of continuous chemical nickel plating
US2983634A (en) * 1958-05-13 1961-05-09 Gen Am Transport Chemical nickel plating of magnesium and its alloys
US2993810A (en) * 1959-03-30 1961-07-25 Douglas Aircraft Co Inc Bath and process for chemically nickel plating magnesium
US3340073A (en) * 1961-05-27 1967-09-05 Bayer Ag Regeneration of chemical plating baths
US4038085A (en) * 1976-03-03 1977-07-26 Chromium Industries, Inc. Method of treating electroless nickel plating bath
WO1999039023A3 (fr) * 1998-01-31 1999-09-23 Lea Associates Limited Ameliorations apportees a un nickelage chimique

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BE573175A (fr) 1959-05-20
CH381047A (fr) 1964-08-14

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