Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D3/00—Electroplating: Baths therefor
  • C25D3/02—Electroplating: Baths therefor from solutions
  • C25D3/12—Electroplating: Baths therefor from solutions of nickel or cobalt
  • C25D3/14—Electroplating: Baths therefor from solutions of nickel or cobalt from baths containing acetylenic or heterocyclic compounds

Definitions

• ABSTRACT OF THE DISCLOSURE This invention comprises a nickel plating process and a nickel electroplating bath containing coumarin or certain derivatives thereof for providing leveling and other desirable characteristics.
• the tendency of the coumarin and related compounds to produce byproducts which cause disadvantageous results in the type of plating is avoided by also having present in the bath an acetylenic compound having the formula HCE CCH OC H OH wherein n equals 1-3.
• This invention relates to electrodepositing nickel from an aqueous acidic nickel plating bath, relating more particularly to a process of and solutions for such electrodeposition utilizing coumarin or substituted coumarins together with certain acetylenic compounds.
• Nickel electroplating baths containing coumarin or certain substituted coumarins are well known for their ability to provide a nickel deposit having superior leveling characteristics as well as producing a deposit which is semibright and reasonably uniform in appearance.
• Semibright deposits are not mirrorlike but are lustrous and are desirable as an undercoat for an outer layer of chromium or of a brighter nickel.
• such semibright nickel deposits cannot be dull or gray, or contain dark areas, or contain areas of much contrast, or they cannot be covered to produce a satisfactory over-all appearance when the outer layer is deposited.
• such semibright nickel deposits must possess other characteristics in order to be acceptable commercially. For example, they must be ductile, free from excessive stress, and have good leveling characteristics; that is, the ability to cover minor imperfections while providing a surface which is much smoother than the surface of the basis metal.
• the use of coumarin and substituted coumarins to produce a satisfactory nickel deposit has been considerably limited, however, because of the formation in the plating bath of acid breakdown products resulting from the reducing action of the electrolysis.
• the principal breakdown product is melilotic acid (o-hydroxy phenyl propionic acid) although trace amounts of other breakdown products are formed. While these other products have not been isolated or even identified definitely, they can cause considerable ditficulty in obtaining a satisfactory semibright deposit, tending to cause embrittle-ment and stressed deposits.
• the melilotic acid and other products also cause stressed deposits and more so as to its concentration increases; and causes the deposit to be gray rather than semibright, particularly in the lower current density portions of the cathode.
• an unagitated nickel plating bath containing about 0.2 g./l. of coumarin, or an air agitated bath containing about 0.1 g./l. will eventually build up a concentration of these products of about 4 g./l.
• the maximum tolerance of the plating bath toward melilotic acid alone, without considering the other breakdown products for the moment, is about 1 g./l.
• these unsaturated compounds when used in coumarin-containing baths, should be used in this range of concentration. Higher concentrations, while producing a bright deposit, also produce striation, brittleness, or other undesirable results. Incidentally, in this small concentration these acetylenic compounds, when used without the coumarin or substituted coumarins, have no appreciable effects on the bath and, in particular, will not cause any noticeable brightening of the deposit. On the other hand, when used without these acetylenics a concentration of about 0.2 g./l. of coumarin for an unagitated bath is needed in order to be effective in improving the leveling and ductility of the nickel deposit.
• Coumarin compounds which have been utilized successfully in plating baths of the present invention include, in addition to coumarin itself (unsubstituted 1,2-benzopyrone), 3-chlorocournarin, 3-bromocoumarin, 3-acetylcoumarin, 7-hydroxy ethyl coumarin, 6-chlorocoumarin, 4,8-dimethyl coumarin, 8-methoxy coumarin, 7-ethoxy coumarin, 6-propargoxy coumarin, and o-acetamido coumarin.
• chloral, bromal, or formaldehyde may be added to the bath if desired. These compounds appear to assist in producing a deposit which is more uniformly semibright and ductile and also in permitting the use of higher plating temperatures.
• chloral, bromal, or formaldehyde have been added to coumarin-containing nickel plating baths previously in an effort to prolong as much as possible the interval between purification treatments (see US.
• the original nickel chloride content was kept at 6.7 ounces per gallon and plating temperature at 150-155 F.
• the original solution was operated at 155 F. with 0.002 gram per liter (0.014 millimole per liter) of diethylene glycol monopropargyl ether added to the original bath.
• the deposit was bright-semibright and smooth and uniform. Also, the deposit was ductile and possessed good leveling characteristics. There was very little change in the deposit when the solution was operated at a pH of 3.5 instead of 4.2.
• a deposit was taken at F. and all of the cathode was slate gray except those portions having a current density over 60 amp/sq. ft.
• the addition of chloral at a concentration of 0.1 gram per liter improved the deposit in that it had a semibright appearance when plated at 135 F. but was dull in many areas when plated at 155 F. Also, the deposit was not ductile enough and tended to be brittle.
• Diethyleneglycol monopropargyl ether was then added at a concentration of 0.002 gram per liter.
• the deposit was uniformly bright and was easily covered by bright nickel. Also, the leveling and ductility improved to the point of being commercially acceptable.
• EXAMPLE III A previously operated sulfamate solution having ten ounces per gallon of nickel, 3 ounces per gallon of nickel chloride, 4.5 ounces per gallon of boric acid, 0.1 g am per liter of coumarin and 0.2 gram per liter of melilotic acid, was operated at F. at a pH of 4.2. In this particular test, bent cathodes were used; that is, cathodes having a V-shaped recess and sharp bends.
• the bath as described above produced semibright nickel at 30-70 amp/sq. ft. but was gray at 11-25 amp/sq. ft. Also, the deposit was quite brittle. To this solution 0.002 gram per liter of diethylene glycol monopargyl ether was added. The deposit was semibright at 12-70 amp/sq. ft. and bright at 5-12 amp/sq. ft. The semibright area was more lustrous. The coating did not contain sharp areas of demarcation and was very satisfactory from the point of view of leveling. The addition of 0.2 cc./l. of Formalin and 0.1 gram per liter of choral produced very little change although the coating tended to have somewhat less sharp lines of demarcation and was more ductile.
• EXAMPLE IV A Watts nickel solution containing 1 gram per liter of melilotic acid and 0.02 gram per liter of coumarin was electrolyzed for two hours with air agitation. This treatment is used to form small amounts of harmful impurities or breakdown products in addition to the melilotic acid. Coumarin was then added in a concentration of 0.012 gram per liter and the temperature and pH were adjusted to F. and 4.0 respectively. Straight, unbent panels were plated at an average of 30 amp./ sq. ft. This low current density provided a severe test because dullness and brittleness are more noticeable under these conditions than at normal current density values. A deposit of 1 mil in thickness was plated. The solution was divided into two cells. The results are stated in Table I below.
• the diethylene glycol monopropargyl ether concentration was increased to 0.02 g./l. Now the deposit had bright and semibright areas with striations at the line of demarcation between semibright and bright areas.
• the ductility varied from 0.14 to 0.45, i.e., was only satisfactory at times. While this "was a brighter deposit than when 0.002 g./l. of diethylene glycol monopropargyl ether had been used, it was not commercially acceptable.
• the additives of the present invention become necessary in practical operating baths; and, as noted hereinbefore, the use of diethylene glycol monopropargyl ether or the other acetylenic compounds hereof in the concentrations recommended will produce a commercially satisfactory deposit when melilotic acid or other breakdown products are present in the bath, producing a deposit which is not only substantially uniformly semibright but possesses the necessary ductility and leveling characteristics to be wholly acceptable commercially.
• a process for electrodepositing a ductile semibright nickel substantially smoother than the basis metal to which it is applied utilizing an aqueous acid electroplating bath containing at least one soluble nickel compound the improvement consisting of conducting such electrodeposition from a bath containing a coumarin compound selected from a group consisting of 1,2-benzopyrone, 3- chlorocoumarin, 3-bromocoumarin, 3-acetylcoumarin, 7- hydroxy ethyl coumarin, 6-chlorocoumarin, 4,8-dimethyl coumarin, S-methoxy coumarin, 7-ethoxy coumarin, 6- propargoxy coumarin, and 6-acetamido coumarin, operating said bath at a temperature of F. to F.
• a coumarin compound selected from a group consisting of 1,2-benzopyrone, 3- chlorocoumarin, 3-bromocoumarin, 3-acetylcoumarin, 7- hydroxy ethyl coumarin, 6-chlorocoumarin, 4,8-d
• a process for electrodepositing a ductile semibright nickel substantially smoother than the basis metal to which it is applied utilizing an aqueous acid electroplating bath containing at least one soluble nickel compound the improvement consisting of conducting such electrodeposition from a bath containing a coumarin com pound selected from the group consisting of 1,2-benzopyrone, 3-chlorocoumarin, 3-bromocoumarin, 3-acetylcoumarin, 7-hydroxy ethyl coumarin, 6-chlorocoumarin, 4,8- dimethyl coumarin, 8-methoxy coumarin, 7-ethoxy coumarin, 6-propargoxy coumarin, and G-acetamido coumarin, operating said bath for such a time as to produce at least 0.5 gram per liter of melilotic acid in said bath, and including therein 0.006 to 0.05 millimole per liter of a compound having a structure represented by the formula HCECCH2(OC2H4)I1OH wherein 11:1,
• a process for electrodepositing a ductile semibright nickel substantially smoother than the basis metal to which it is applied utilizing an aqueous acid electroplating bath containing at least one soluble nickel compound the improvement consisting of conducting such electrodeposition from a bath containing a coumarin compound selected from a group consisting of 1,2-benzopyrone, 3-chlorocoumarin, 3-bromocournarin, 3-acetylcoumarin, 7-hydroxy ethyl coumarin, -chlorocoumarin, 4,8- dimethyl coumarin, S-methoxy coumarin, 7ethoxy coumarin, 6-propargoxy coumarin, and -acetamido coumarin, operating said bath at a temperature of 140 F.
• a coumarin compound selected from a group consisting of 1,2-benzopyrone, 3-chlorocoumarin, 3-bromocournarin, 3-acetylcoumarin, 7-hydroxy ethyl coumarin, -chlorocoumarin
• a nickel electroplating bath adapted to produce a ductile sernibright nickel deposit substantially smoother than the basis metal to which it is applied comprising an aqueous solution of at least one nickel salt and in which there is dissolved at least 0.5 gram per liter of a coumarin compound selected from the group consisting of 1,2-benzopyrone, 3-chlorocoumarin, 3-bromocoumarin, 3-acetylcoumarin, 7-hydroxy ethyl coumarin, 6-chlorocoumarin, 4,8-dimethyl coumarin, 8-methoxy coumarin, 7-ethoxy coumarin, 6-propargoxy coumarin, and 6-acetamido coumarin, at least 0.5 gram per liter of melilotic acid, and 0.006 to 0.05 millimole per liter of a compound having a structure represented by the formula wherein 11:1, 2, or 3.
• a nickel electroplating bath adapted to produce a ductile semibright nickel deposit substantially smoother than the basis metal to which it is applied comprising an aqueous solution of at least one nickel salt and in which there is dissolved at least 0.5 gram per liter of a coumarin compound selected from the group consisting of 1,2-
• a nickel electroplating bath adapted to produce a ductile semibright nickel deposit substantially smoother than the basis metal to which it is applied, comprising an aqueous solution containing 30 to 60 ounces per gallon of nickel sulfate and 6 to 10 ounces per gallon of nickel chloride in which there is dissolved at least 0.5 gram per liter of a coumarin compound selected from a group consisting of 1,2-benzopyrone, 3-chlorocoumarin, 3-bromocoumarin, 3-acetylcoumarin, 6-hydroxy ethyl coumarin, 6-chlorocoumarin, 4,8-dimethyl coumarin, S-methoxy coumarin, 7-ethoxy coumarin, 6-propargoxy coumarin, and 6-acetamido coumarin, at least 0.5 gram per liter of melilotic acid, and 0.006 to 0.05 millimole per liter of a compound having a structure represented by the formula HCECCH (CH H ),,OH wherein 11:
• a nickel electroplating bath adapted to produce a ductile semibright nickel deposit substantially smoother than the basis metal to which it is applied comprising an aqueous solution containing 30 to 60 ounces per gallon of nickel sulfate and 6 to 10 ounces per gallon of nickel chloride and in which there is dissolved at least 0.5 gram per liter of a coumarin compound selected from a group consisting of 1,2-bcnzopyrone, 3-chlorocoumarin, 3-bromocoumarin, 3-acetylcoumarin, 6-hydroxy ethyl coumarin, 6-chlorocoumarin, 4,8-dirnethyl coumarin, 8- methoxy coumarin, 7-ethoxy coumarin, 6-propargoxy coumarin, and 6-acetamido coumarin, at least 0.5 gram per liter of melilotic acid, and 0.006 to 0.5 millimole per liter of a compound having a structure represented by the formula HCECCH (OC H OH wherein

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  • NL NL133678D patent/NL133678C/xx active
• 1965
  • 1965-10-22 US US502603A patent/US3414491A/en not_active Expired - Lifetime
• 1966
  • 1966-10-18 GB GB46482/66A patent/GB1093490A/en not_active Expired
  • 1966-10-21 FR FR80966A patent/FR1508159A/fr not_active Expired
  • 1966-10-21 ES ES0332548A patent/ES332548A1/es not_active Expired
  • 1966-10-21 NL NL6614936A patent/NL6614936A/xx unknown
  • 1966-10-21 DE DE19661496830 patent/DE1496830B1/de active Pending

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