US2233500A - Electroplating zinc - Google Patents

Electroplating zinc Download PDF

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US2233500A
US2233500A US98455A US9845536A US2233500A US 2233500 A US2233500 A US 2233500A US 98455 A US98455 A US 98455A US 9845536 A US9845536 A US 9845536A US 2233500 A US2233500 A US 2233500A
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bright
dipped
bath
zinc
cyanide
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US98455A
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Leon R Westbrook
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EIDP Inc
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EI Du Pont de Nemours and Co
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Priority to NL52721D priority Critical patent/NL52721C/xx
Priority to NL54393D priority patent/NL54393C/xx
Priority to US98455A priority patent/US2233500A/en
Application filed by EI Du Pont de Nemours and Co filed Critical EI Du Pont de Nemours and Co
Priority to CH203152D priority patent/CH203152A/de
Priority to CH220132D priority patent/CH220132A/de
Priority to CH220133D priority patent/CH220133A/de
Priority to DE1937P0075757 priority patent/DE693832C/de
Priority to DEP2357D priority patent/DE882168C/de
Priority to FR826935D priority patent/FR826935A/fr
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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
    • C25D3/00—Electroplating: Baths therefor
    • C25D3/02—Electroplating: Baths therefor from solutions
    • C25D3/22—Electroplating: Baths therefor from solutions of zinc
    • C25D3/24—Electroplating: Baths therefor from solutions of zinc from cyanide baths

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  • Thisinvention relates to the electrodeposition of zinc, and is particularly directed to processes and plating solutions wherein a bright, mirrorlike' zinc deposit is plated from a cyanide-zinc 5: bath which contains both an organic addition agent and a brightening metal. is further directed to the bright zinc deposits obtained, to the processes of obtaining such deposits from cyanide-zinc plating baths, and to processes and solutions employing an oxyheterocyclic compound and a brightening metal.
  • Electrodeposition of zinc, or electrogalvanizing has been rather extensively employed because electro deposited zinc coatings, in addition to their low cost, display many characteristics which cause them to be particularly desirable as protective finishes.
  • Zinc being higher in the lectromotive series, will protect iron or steel against rust even after appreciable areas of the base metal are exposed, whereas the corrosion of iron or steel is accelerated by such metals as copper, nickel, and chromium.
  • electrodeposited zinc coatings have not enjoyed the use they deserve because ordinarily they do not possess and do not retain a pleasing appearance, and, consequently, for many purposes they are not acceptable.
  • the electrodeposition of zinc has ordinarily w .beenaccomplished by the use of either an acidzinc bath or a cyanide-zinc bath. With neither of these baths has it been possible to obtain satisfactorily smooth and bright deposits, but the acid-zinc bath is more commonly used because :it leads to a brighter deposit with a better color than does the cyanide-zinc bath.
  • cyanide-zinc baths While the deposits obtained from cyanide-zinc 2 baths are poor in appearance, they'have a relatively flne crystalline structure. A few addition agents, suchas alum, gum arabic, and fluorides, have been tried in cyanide-zinc baths, but the results obtained were nonev too satisfactory. Aside from the poor appearance of deposits obtainable therefrom, cyanide-zinc baths have a number of advantageous characteristics. They have good throwing power, audit is therefore possible to deposit a relatively uniform zinc coating on irregularly shaped and recessed articles; Cyanide-zinc baths, moreover, have a relatively high cathode emciency which, of course, is very advantageous because the electric current applied to the bath is expended less upon the evolution of hydrogen, and. more upon the deposition of zinc.
  • the use of a bright-dip is illogical and uneconomical.
  • the brightdip removes some of the zinc, and it is wasteful of time, materials, and.
  • the baths of this invention have great throwing power and extremely xwide bright current density ranges and, unlike the baths of the prior art, they produce uniform zincc'oatings even on recessed articles. It is thereforeunnecessary to use bright-dips for the purpose, of making .the
  • This invention in its broader aspects, includes some baths which do not produce deposits of the highest brilliance, but which are, nontheless, a distinct improvement over the baths at present in commercial use. It may sometimes be sufilcient to produce deposits of moderate brightness, and, in any event, a bright-dip can be employed with results superiorto those of the prior art.
  • a number of metals may advantageously be used to produce deposits of great smoothness and brightness. These metals appear to' exercise some synergetic action in conjunction with organic addition agents, and this action is particularly noticeable when the metals" are used in conjunction with oxyheterocyclic addition agents. Most of the orwheterocyclic compounds seem'to have only a small effectjwhen used in cyanide-zinc baths in the absence of a brightening metal. As will be noted later, however, heterocyclic compounds may sometimes be used alone for the benefit which they do offer.
  • Oxyheterocyclic compounds typical of which are furfuralderivatives, coumarin, pyronine, and pip r-opal, are, of course, characterized by the The bright-.fdip treatment, moreovenf- The zinc should be de- The deposits produced acpresence of an oxy 'eterocyclic ring, and it is be lieved that it is this characteristic which determines the suitability of compounds for my purposes.
  • An oxyheterocyclic ring is, of course, a cyclic ring of carbomand oxygen atoms.
  • the oxyheterocyclic addition agents employed should be relatively stable in the bath. That is, they should not lose their oxyheterocyclic form upon contactiwith a cyanidezinc plating solution.
  • the compounds moreover, should be at .least slightly soluble in a cyanide plating bath.
  • the brightening metals to be used in conjunction' with oxyheterocyclic compounds according to this invention include aluminum, titanium, and metals found in sub-groupl of groups VI and VII, and-'in group VIII series 4 of Mendelyeevs periodic arrangement of the elements. Most of these 'metals themselves exercise a profound effect upon thecharacter of zinc electrodeposits obtained from cyanide-zinc plating baths, and,
  • Molybdenum is by far the guest satisfactory of the brightening metals .for use with oxyheterocyclic compounds, the deposits obtainable by the use of such a combination being markedlysuperior to those obtainable with most other'combinations disclosed herein.
  • Thebrightening metals molybdenum, chromium, tungsten, and uranium found in group VI sub-group 1, may be addedto a cyanidezinc bath in the form of a niolybdate, chromate, tungstat, or uranate of sodium or potassium, or other such compounds which are soluble inthe bath.
  • the metals of group VlI sub-group 1, manganese and rhenium simllarly, should be added in the form of soluble compounds.
  • Aluminum may be added as aluminum sulfate, and titanium may be added as titanyl sulfate. a
  • the metals of group VIII series 4 0i' the periodic system have little eifect upon the character of a' zinc electrodeposit when used alone but, in com-' mon with the other brightening metals, they ex-, 4
  • the metals of group VIII-series '4 are also advantageously employed by reason of their effect upon the metals of sub-group Iof groups VI and VII. These metals may be added to the bath in the form of such alkali or cyanide soluble compounds as potassium ferrocyanide, co-
  • balt sulfate nickel sulfate, cobalt oxide, and nickel oxide.
  • cyanide-zinc bath The combination of an oxyheterocyclic compound and a brightening metal is employed in a cyanide-zinc bath, numerous examples of which will be given hereinafter. While the cyanide-zinc baths shown herein are typical, it will be understood that the principles of my invention are applicable to any cyanide-zinc plating bath. To obtain the best results it is desirable that the cyanide-zinc plating bath be as pure as possible, and it is particularly important that lead compounds be absent.
  • I designates a box having a cover 2 and divided by a central partition I.
  • a light source 3 a fifty candlepower automobile headlight bulb.
  • a storage battery is used, the current being regulated by the use of a rheostat so that about three volts are supplied to the lamp.
  • a concave mirror 4 which serves to intensifythe light to some extent. This concave mirror is about three inches below the bulb.
  • the light bulb there is a black partition 5 provided with a one-half inch slit.
  • the bulb is about threeand one-half inches from the specimen being tested.
  • the photoelectric cell is on a slight incline, being supported by the member 8. The cell is about five and one-half inches from the specimen.
  • the photoelectric cell is connected to a microammeter III which shows directly the number of microamperes generated by the cell in response to the light reflected by the specimen.
  • the top .2 of the box I has a slit H therein thru which light can pass.
  • a metal plate I2 is set over the hole, the plate having a one-quarter by three-quarter inch rectangular slit.
  • the refiectometer Before starting to use the refiectometer, it was calibrated with a standard reflecting surface. A silverv mirror was made by plating a polished copper sheet with silver and then bufllng. The mirror was placed face down on the chamois over the slit. The current supplied to the bulb 3 was then adjusted until the micro-ammeter read 49.
  • a silvered glass mirror was placed face down depending upon its temperature and upon other variables. At frequent intervals a new polished silver mirror was prepared in accordance with the best practice and used to recheck the glass mirror so that when the silver mirror read 49 microamperes, a portion of the glass mirror reading 45 microamperes would be used as standard. c
  • specimens were plated on polished copper sheets at current densities from flve to one hundred and fifty amperes per square foot. Specimens plated at current densities of about seven, twenty-five, forty, and eighty amperes per square foot were placed on the reflectometer for brightness determinations.
  • Example 1 The oxyheterocyclic compound piperonal is a colorless crystalline material sparingly soluble in water and in cyanide-zinc plating baths.
  • the compound is also known as heliotropin and as 3,4-methylenedioxybenzaldehyde, and it is characterized by an intense heliotrope-like odor.
  • a cyanide-zinc plating bath was made up according to the above standard m thod, and there was added thereto:
  • the piperonal does not deteriorate in the bath as do certain oxyheterocyclic addition agents: mentioned hereinafter. It is interesting to note that the presence 'of piperonal in a bath such as the one of this example seems-to increase Zinc cyanide (Zn(CN)z) 60 Sodium cyanide (NaCN); 23 Sodium hydroxide (NaOH) 53 slightly the content of molybdenum in the deposit, o
  • the cyanide-zinc plating bath used as standard in this application was made up without the use of addition agents, and a number of deposits made therewith.
  • the following brightness read- 1112s were obtained: I A II Current density. (amps. per sq.
  • a cyanide-zinc plating bath was madeupusing 3.5 grams per liter of .piperonal but omitting molybdenum. Zinc electro-deposits' obtained 25 to so".
  • the chromium slowly precipitates from the solution, and for this reason is not as desirable a metal brightener asrmolybdenum.
  • the metal content of the bath can, of course, be maintained by adding chromiumsulfateto-replace the chromium which leaves the solution.
  • the bath was made up with very pure zinc oxide, sodium hydroxide, and sodium cyanide, and electrolytic zinc anodes were employed to avoid the responds to about two grams per liter of molyb-,
  • Example 4 A cyanide-zinc plating bath employing a combination of metals of Group VI sub-group 1, Group VII sub-group 1, and Group VII series 4 was made up as follows: r
  • Zinc oxide 45 Sodium hydroxide (NaH) s.. 38 Sodium cyanide (NaCN) I00 Manganese-cyanide 10 I Potassium ferrocyanide (K4Fe(CN) c.3HaO) Molybdenum trioxlde (M003) 4 Piperonal 3 1 Zinc deposits made from the bath of this example were of about the same appearance regardless of current density. Irregularly shaped objects, accordingly, were given a coating of very uniform appearance by the use of this bath. The reflectometer readings were as follows:
  • the cobalt sulfate used corresponds to about one and twenty eight hundredths of a gram per liter of cobalt. Very similar results were obtained using sixty four hundredths of a gram per liter of cobalt, or about four grams per liter of cobalt sulfate.
  • the manganese sulfate corresponds to about twenty-five hundredths of a gram per liter of manganese. Both the piperonal and the manganese sulfate were used in about the maximum amount soluble in the bath. 'More manganese sulfate was added to the bath in various tests without appreciably different results being obtained. Excellent results were obtained using the bath of this example, and the following reflectometer readings were noted:
  • Zinc oxide ZnO
  • Sodium hydroxide NaOH
  • NaCN Sodium cyanide
  • WOa Tungsten trioxide
  • the tungsten trioxide used corresponds to about six and four-tenths grams per liter of tungsten.
  • Specimen plates were made up at the below indicated current densities with the following resuits:
  • a cyanide-zinc plating bath was also made up as above using piperonylic acid but omitting the molybdic acid. When not using the metal bright- Current density '1 25. 4o so Not bright-dipped. 18 iv 16 11 Bright-dipped 30 33 30 21
  • Example 13 A cyanide-zinc plating bath was made up with:
  • Cobalt sulfate (00301-71110) 8 Another oxyheterocyclic compound closely allied to piperonal is piperine. This compound is characterized by the presence of the methylene dioxyphenyl group. Piperine is only slightly soluble in water, and in the following examples it was added to the cyanide-zinc baths in alcohol solution. A bath employing this oxyheterocyclic compound together with my preferred met brightener was madeup with: g i
  • Example 18 A cyanidezinc plating bath was made up with:
  • Nickel ammonium sulfate v (NiBOdNHshSOs-BHsO) 1 Piperine 1 Plates made using this both were quite satisfactory without bright-dipping and. as is usual with deposits made employing nickel, bright-dipping was not advantageous.
  • Zinc cyanide Zn(CN)2 60.
  • Sodium hydroxide NaOH 80.
  • Sodium cyanide NaCN 40.
  • Molybdenum trioxide M003) 8.4 Coumarin 3.
  • the coumarin may be used in varying amounts in the bath, of course, the amounts used in this example being about optimumL. This concentra- 4 tion is about the upper limit of the solubility of coumarin in the bath used. Smaller amounts of coumarin may advantageously be employed and results which were not greatly difierent were obtained when one gram per liter of coumarin was used in a bath of the samecomposition. Even smaller amounts of coumarin exercise a beneilcial eflect, the in general itis preferable to use about one gram per liter or more.
  • Zinc oxide 45. Sodium hydroxide (NaOI-IL'. '38. Sodium cyanide (NaCN) 100. Molybdenum trioxide (M003) 3. Manganese-cyanide 2.5
  • the bath was made up with very pure zinc oxide. sodium hydroxide, and sodium cyanide, and electrolytic zinc anodes were employed to avoid the introduction of deleterious impurities into the. bath.
  • the manganese was-added to the bath in the form of a manganese-cyanide complex which was precipitated from a water solution of manganese sulfate by adding thereto a water solution of sodium cyanide.
  • the amount of manganese cyanide used is equivalent to about twentiflve I
  • a cyanide-zinc bath containing a metallic brightening agent from group VII sub-group 1 as well as an oxyheterocylic compound was made up as follows:
  • Manganese sulfate (MnSOuiI-hO) 1 C'oumarin 3 A number of deposits were made using this bath and it was found that the bath has a more restricted bright range than does the bath of the preceding example. -At a current density of about twenty-five amperes per square foot, an unbright-dipped plate had a reflectometer reading of twenty-one and a bright-dipped plate a reading of thirty-four. Manganese sulfate was also used to the amount of fifteen grams per liter in a bath such as that of this example without greatly different results being obtained.
  • Example 28 I A cyanide-zinc plating bath similar to tho of the above examples but containing a metal brightener of group VI sub-group l was made up as follows:
  • Example 29 A cyanide-zinc bath using a metal brlghtener from group VIII series 4 together with an oxyheterocyclic compound was made up as follows:
  • Example 30 A cyanide-zinc bath employing brightening metals of group VI sub-group, group VJI subgroup 1, and group VIII series 4, as well as an oxyheterocyclic compound was made up as follows:
  • Example 31 A cyanide-zinc plating bath was made up with:
  • Molybdenum trioxide 8 Furfural 6 It is observed that the molybdenum trioxide used corresponds to about five and four-tenths grams per liter of molybdenum.
  • a number of polished copper plates were given a coating of zinc at current densities from about three to about one hundred and fifty amperes per square foot. Over this wide range of current densities the zinc deposits were brilliant and lustrous, re-' fleeting images with mirror-like fidelity when observed visually.
  • furfural in conjunction with 'molybdenum leads to exceptionally good results when the bath is fresh, after a short time the bath deteriorates becoming less and less satisfactory. Not only does the effectiveness of the furfural seem to diminish, but some action appears to occur which results in a poisoning of the solution. The addition of more furfural does not revivify the bath. Furfural, then, can only be used to produce very brilliant deposits for a relatively short time.
  • furfural is used at about an optimum concentration in this example, the amount employed may be widely varied. It is generally desirable to use from about two grams per liter to about five grams per liter of furfural in baths of the type of this example.
  • Another oxyheterocyclic compound which may be used with metallic brighteners according to my invention is furfuran.
  • This oxyheterocyclic compound may be considered a furfural' derivative which contains the characteristic oxyheterocyclic ring of four carbon atoms and one oxygen atom.
  • a cyanide-zinc plating bath was made up with: 6mm per liter Molybdenum trioxide (M003) 8 Furfuran 5 Excellent zinc deposits were obtained using this bath.
  • Molybdenum trioxide M003
  • Furfuran 5 Excellent zinc deposits were obtained using this bath.
  • the following refiectometer readings' were taken at the indicated current densitiesz Current density 7 25 40 so Not bright-dipped"; 1'6 28 29 26 Bright-dipped 25 32 35 so furan but omitting molybdenum.
  • the following reflectonieter readings were obtained on deposits made at the indicated currentdensities:
  • Zinc oxide Zinc oxide
  • NaOH Sodium hydroxide
  • NaCN Sodium cyanide
  • MnSO4-4HaO Manganese sulfate 15 Furfuran 7
  • the manganese sulfate employed corresponds to about three and seven-tenths grams per liter of manganese.
  • Zinc deposits were made on polished copper sheets, and at a current density of about seven amperes per square foot an unbright-dipped deposit gave a refiectometer reading of twenty four, and a bright-dipped deposit gave a reading of thirty three.
  • Emmple 37 A cyanide-zinc plating bath was made up with:
  • Molybdenum trioxide (M003) 8 Pyronine 5 This bath was employed to zinc plate a number of polished copper sheets and a number of commercial steel articles. The zinc deposit on the polished copper sheets was brilliant and lustrous, and reflected images with a mirror-like fidelity when visually observed. Zinc deposits made at the indicated current densities gave the following reflectometer readings:
  • Zinc oxide 45 Sodium hydroxide (NaOH) 38 Sodium cyanide (NaCN) Tungsten trioxide (W03) 5 Pyronine 2
  • the tungsten trioxide corresponds to about four grams per liter of tungsten.
  • the deposits obing bath made up with:
  • Example 41 A cyanide-zinc bath using a metal of group VI sub-group land a. metal of group VIII series 4 as well as an oxyheterocyclic compound, was made up asfollows: U
  • Zinc oxide 45 Sodium hydroxide (NaOH) 38 Sodium cyanide (NaCN) Molybdenum trioxide (M003) 2 Cobalt sulfate (C0SO4-7H2O) 1 Pyronine 2
  • the molybdenum trioxide corresponds to about one and three-tenths grams per liter of molybdenum and the cobalt sulfate corresponds to about twenty-one hundredths of a gram per liter of cobalt.
  • Zinc deposits made employing this bath were of good character. Deposits made at a current density of about twenty-five amperes per square foot gave a reflectometer reading without bright-dipping of about twenty-four, and bright-dipped, a reading of thirty-sthree.
  • Example 42 A cyanide-zinc plating bath was made up with:
  • Example A cyanide-zinc plating bath was made up with:
  • Titanyl sulfate (TiOSOi) 0.5 Furfuryl-a 5.0
  • a cyanide-zinc bath was made up using eight.
  • Example 49 Euroin is another example of an oxyheterocyclic compound which may be considered as a 15 furfural derivative and which is characterized by the presence of an oxyheterocyclic ring of four carbon atoms and one oxygen atom.
  • a cyanide-zinc plating bath was made up with:
  • Titanyl sulfate (TiOSO4) 1 Furoin 5 The following results were obtained using this bath:
  • Hydrofurfuramide is still another oxyheterocyclic compound which may be considered as a furfural derivative, and it is characterized by the presence of an oxyheterocyclic ring of four carbon atoms and one oxygen atom.
  • a bath was made up with:
  • a cyanide-zinc plating bath was also made up wit five grams per liter of hydrofurfuramide omitting the molybdenum. With this bath the following results were obtained:
  • Furoic acid is another furfural derivative characterized by the presence of an oxyheterocyclic ring of four carbon atoms and one oxygen atom.
  • a cyanide-zinc plating bath was made up with:
  • Example 56 A cyanide-zinc plating bath employing the oxyheterocyclic compound paraldol was made up with: V
  • Example 58 A cyanide-zinc plating bath was made up with:
  • Ethyl furoate is an oxyheterocyclic compound which may be regarded as a derivative of furfural. Like furfural, it contains'an oxyheterocyclic ring of four carbon atoms and one oxygen atom. Employing this compound a bath was made up with:
  • Methyl furoate is an oxyheterocyclic compound very similar to the one of the preceding example.
  • a cyanide-zinc plating bath was made up with:
  • Example 63 Another oxyheterocyclic compound which may be considered a derivative of furfural is furfurylamine. This compound, like iurfural, is characterized by the presence of an oxyheierocyclic ring made up with four carbon atoms and one oxygen atom. A cyanide-zinc plating bath was made up with: I
  • T1OSO4 Titanyl sulfate
  • Furfuramide 3 Deposits of uniform appearance were obtained, but they were not unusually bright. At a current density of about forty amperes per square foot an unbright-dipped plate gave a reflectometer reading of twenty one, and a bright-dipped plate gave a reading of twenty seven.
  • Tetrahydrofurfurylamine is another furfural, derivative characterized by the presence of an oxyheterocyclic ring of four carbon atoms and one oxygen atom.
  • a cyanide-zinc plating bath was made up with:
  • Chromium sulfate (Cr(SO4)3-15mO) 4 Dihydroxymethylxanthene 5 A number of specimens were electrodeposited on polished copper sheets, and reflectometer readings obtained 'at the indicated current densities as follows:
  • a cyanide-zinc plating bath was made up with: Grams per liter *Aluminum sulfate (A12(S O4)3) 12 Dihydroxymethylxanthene 5 Zinc specimens plated employing this bath gave the following results:
  • a cyanide-zinc plating bath was made up with:
  • Example 74 A cyanide-zinc plating bath was made up with: Grams per liter Molybdenum trioxide (M002) 8 Morpholine Employing this bath, zinc deposits were made up and the following results obtained:
  • Phenylmorpholine hydrochloride 0.5 It is observed that larger amounts of the phenylmorpholine hydrochloride were not soluble in the bath. Employing this bath. cyanide-zinc deposits were made and the following reflectometer readings obtained at the indicated current densities:
  • Example 80 An oxyheterocyclic compound similar to that of the preceding example was used in a cyanide-zizic plating hath made up with:
  • Example 82 acid was included in a cyanide-zinc plating bath
  • a cyanide-zinc plating bath was made up with: made up with Grams per liter Grams per liter Molybdenum trioxide (M003) a Molybdenum trioxide (M003) a Coumalic acid 3 Cyclohexene oxide" 3 While three grams per liter of cyclohexene oxide wereadded, probably not more than one gram per liter was actually dissolved. The remainder formed an oily film on the surface of the bath. During electrolysis the film became dark brown in color. The following results were obtained when the bath was used to plate specimen zinc deposits on polished copper sheets:
  • a cyanide-zinc plating bath was made up including:
  • deposits made at a current density of about forty amperes per square foot gave, before bright-dipping, a reflectometer reading of twenty-three, and, after bright-dipping, a reading of thirty-five. It appears that phthalide is not stable in the bath because upon standing a dark precipitate formed.
  • Example 89 I 1 A cyanide-zinc plating bath was made up with:
  • the metals of group VI sub-group 1 may be used in widely varying amounts, the upper limit on the quantity being largely determined by economic considerations. In view of the high cost of the metals of this group, it would not at the present time be commercially feasible to employ them in large quantities. More specifically, the metals of group VI sub-group 1' should be used in amounts not substantially less than about one hundredth of a gram per liter, and no more than about forty grams per liter can economically be used.
  • Molybdenum is the best metal of this group and it is, in fact, by far the best of the brightening metals. I generally prefer to use from about twenty-five hundredths of a gram to twentyfive grams per liter of molybdenum. More specifically, it is preferred to use from about one to twelve grams per liter of molybdenum. It will be understood that while reference is made to the amount of metal used, the metal is present in the bath in the form of a soluble compound.
  • the metals of group VII sub-group 1 should also be employed in substantial amounts. It is generally desirable to use no less than about five-thousa'ndths of a gram per liter and not substantially more than about fifteen grams per liter. Manganese is preferably usedin amounts between about one and five grams per liter, while, more specifically, about one to three grams per liter should be used.
  • the metals of group VIII series 4 similarly, should be used in substantial amounts as soluble compounds such as potassium. ferrocyanide, co-
  • bait sulfate, cobalt chloride, cobalt oxide, nickel sulfate, nickel chloride, and nickel oxide Generally a soluble compound equivalent to no less than about five-hundredths of a gram per liter of one of these metals should be used.
  • titanium When titanium is employed as a brightening metal, an amount equivalent to about one-half gram per liter of titanyl sulfate should be used, tho, of course, larger or smaller amounts may be employed if desired.
  • the amount of aluminum used as a brightening metal may be greatly varied, it is generally desirable to employ an amount of aluminum equivalent to about five to twelve grams per liter of aluminum sulfate.
  • Each of the brightening metals has characteristics peculiar to itself, and the selection of a metal brightener for a particular bath may be infiuenced by the characteristics desired. While, generally speaking, I may employ any metal brightener in conjunction with organic addition agents, it is preferred to use a metal from the group consisting of molybdenum, chromium, cobalt, manganese, nickel, iron, titanium, rhenium, aluminum, and tungsten.
  • Molybdenum is by far the best of the brightening metals as has been'pointed out above, the occasionally some other brightening metal will give comparable results in a particular combination.
  • Chromium is very satisfactory as a brightening metal, but it has the fault of vhydrolyzing in the bath and precipitating out. This characteristic of chromium brighteners makes their use too expensive for most purposes.
  • cobalt is used as a metal brightener the deposits appear a little white, and the refiectometer readings are lower than one would expect from visual observation.
  • the deposits When manganese or tungsten are used as brightening metals, the deposits have a brownish film. Despite the fact that many deposits of pleasing and brilliant appearance are obtained using these metals, the deposits almost uniformly give much lower refiectometer readings than would be expected from visual observation. The brownish film is removed when the deposits are bright-dipped.
  • Iron like manganese and tungsten, causes the formation of a slight film on the deposit. This film also lowers the refiectometer readings without making the plates appear correspondingly dull to the eye. The film, however, is removed by bright-dipping.
  • Titanium occasionally causes the formation of a slight gray film which greatly lowers the reflectometer readings.
  • the gray film is not ordinarily removed by bright-dipping the deposit.
  • Rhenium is quite excellent as a brightening metal, but it is so rare atthe present time that its commercial application would be impractical. Should the metal become less expensive, it could be used very satisfactorily as a brightener.
  • oxyheterocyclic compound should retain its oxy heterocyclic structure in cyanide-zinc plating baths and, of course, the compound should be to some extent soluble in the bath. If an oxyheterocyclic compound is not readily soluble, it may be more satisfactorily dissolved by adding it in a solvent such as alcohol or acetone.
  • I may employ any oxyheterocyclic compound with or without a metal brightener, it is preferred to employ an oxyheterocyclic compound from the group consisting of piperonal, piperonyl alcohol, piperonylic acid, piperine, safrole, piperonal acetophenone, coumarin, furfural, furfuran, pyronine, tetrahydrofurfuryl alcohol, hydrofurfuramide, paraldol, ethyl furoate, methyl furoate, furfural amine, tetrahydrofurfuralamine, dihydroxymethylxanthene, fluorescein, morpholine ethanol, phenyl morpholine hydrochloride, butyl morpholine hydrochloride, diphenylene oxide, cyclohexene oxide, glycol formahcoumalic acid, and furfuramide.
  • an oxyheterocyclic compound from the group consisting of piperonal, piperonyl alcohol, piper
  • the oxyheterocyclic compounds are preferably employed in about the amounts given in the above examples. It will be understood that the quantity used in the examples was determined in each instance by trying. the organic addition agent at widely varying concentrations until about an optimum was found. If it is desired to employ a particularoxyheterocyclic compound in a still different. specific instance, the amount to be used may readily be determined by a few simple tests.
  • the brightness figures given in the above examples refer, of course, to the number of micro- .amperes read on the micro-ammeter III of the refiectometer.
  • the figures are therefore specific to the apparatus used for the determinations.
  • the data can be given an absolute significance by referring to a silver mirror.
  • a plate with a refiectometer reading of 38 microamperes is as bright as a polished silver mirror.
  • the step comprising depositing zinc from a cyanide-zinc bath in the presence of an oxyheterocycle compound.

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US98455A 1936-08-29 1936-08-29 Electroplating zinc Expired - Lifetime US2233500A (en)

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NL52721D NL52721C (en)) 1936-08-29
NL54393D NL54393C (en)) 1936-08-29
US98455A US2233500A (en) 1936-08-29 1936-08-29 Electroplating zinc
CH220132D CH220132A (de) 1936-08-29 1937-08-19 Verfahren zur elektrolytischen Herstellung von Zinküberzügen.
CH203152D CH203152A (de) 1936-08-29 1937-08-19 Verfahren zur elektrolytischen Herstellung von Zinüberzügen.
CH220133D CH220133A (de) 1936-08-29 1937-08-19 Verfahren zur elektrolytischen Herstellung von Zinküberzügen.
DE1937P0075757 DE693832C (de) 1936-08-29 1937-08-20 Bad und Verfahren zur elektrolytischen Herstellung von Zinkueberzuegen
DEP2357D DE882168C (de) 1936-08-29 1937-08-20 Bad und Verfahren zur elektrolytischen Herstellung von Zinkueberzuegen
FR826935D FR826935A (fr) 1936-08-29 1937-08-27 Procédé d'obtention électrolytique de revêtements de zinc

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2479670A (en) * 1944-03-20 1949-08-23 Poor & Co Electroplating baths and method for the electrodeposition of zinc
US2635076A (en) * 1947-01-29 1953-04-14 Harshaw Chem Corp Bright nickel plating
US2646397A (en) * 1950-11-18 1953-07-21 Wean Engineering Co Inc Electroplating zinc using titanium containing electrolyte
US2994126A (en) * 1957-10-29 1961-08-01 Porter Co Inc H K Ferrous metal body with alloyed zinc coating
US3268422A (en) * 1960-06-09 1966-08-23 Nat Steel Corp Electroplating bath containing aluminum and manganese-bearing materials and method of forming aluminummanganese alloy coatings on metallic bases
US3791801A (en) * 1971-07-23 1974-02-12 Toyo Kohan Co Ltd Electroplated steel sheet
US3850766A (en) * 1974-03-28 1974-11-26 Sterwin Chem Inc Electroplating brightener compositions and process

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1109479B (de) * 1959-01-03 1961-06-22 Riedel & Co Bad und Verfahren zum galvanischen Abscheiden hochglaenzender Zinkueberzuege

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2479670A (en) * 1944-03-20 1949-08-23 Poor & Co Electroplating baths and method for the electrodeposition of zinc
US2635076A (en) * 1947-01-29 1953-04-14 Harshaw Chem Corp Bright nickel plating
US2646397A (en) * 1950-11-18 1953-07-21 Wean Engineering Co Inc Electroplating zinc using titanium containing electrolyte
US2994126A (en) * 1957-10-29 1961-08-01 Porter Co Inc H K Ferrous metal body with alloyed zinc coating
US3268422A (en) * 1960-06-09 1966-08-23 Nat Steel Corp Electroplating bath containing aluminum and manganese-bearing materials and method of forming aluminummanganese alloy coatings on metallic bases
US3791801A (en) * 1971-07-23 1974-02-12 Toyo Kohan Co Ltd Electroplated steel sheet
US3850766A (en) * 1974-03-28 1974-11-26 Sterwin Chem Inc Electroplating brightener compositions and process

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Publication number Publication date
DE693832C (de) 1940-07-19
CH220133A (de) 1942-03-15
DE882168C (de) 1953-07-06
NL52721C (en))
NL54393C (en))
FR826935A (fr) 1938-04-13
CH203152A (de) 1939-02-28
CH220132A (de) 1942-03-15

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