Classifications

• • 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
  • C25D5/10—Electroplating with more than one layer of the same or of different metals
  • C25D5/12—Electroplating with more than one layer of the same or of different metals at least one layer being of nickel or chromium
• • 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
  • C25D3/04—Electroplating: Baths therefor from solutions of chromium
• • 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
• • 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
  • C25D5/627—Electroplating characterised by the visual appearance of the layers, e.g. colour, brightness or mat appearance

Definitions

• This application relates to the electrodeposition of bright chromium on basis metals or substrates from hexavalent chromium plating baths at high current efficiencies and with high adhesion quality.
• Chromium plating baths containing halides have exhibited adhesion problems. Such baths are of the types disclosed in Mitsui, J7B-33941 (Sept., 1978); Dillenberg, U.S.Patent 4,093,522; Perakh et al., U.S. Patent 4,234,396; and copending U.S. patent Application No. 06/295,430, filed August 24, 1981.
• Anodic chromic acid treatments for 400 stainless steel alloys and for low and high carbon steels is disclosed in "48th Metal Finishing Guidebook - Directory” 78, 188-202 (1980) by A. logozzo. Also recommended are cathodic treatments in sulfuric-fluoride solutions for 300 stainless, for nickel alloys and for cast iron.
• an adherent chromium deposit is obtained on a metal substrate by means of a process which comprises the steps of subjecting the substrate to an adherent iron containing deposit, followed by a chromic acid anodic treatment and depositing chromium on the treated, iron containing deposit from a bath containing a halogen releasing compound selected from the group consisting of iodine releasing compounds, bromine releasing compounds and mixtures thereof.
• Supplemental catalysts such as sulfates, simple and complex fluorides, borates, carboxylates, chlorides, chlorates and perchlorates can also be present.
• the process can further include the step of activating the substrate metal in an acid bath or an iron or an iron alloy plating bath prior to iron plating from an iron salt containing bath.
• rods 9.5 mm in diameter (3/8 inch) were held in a holder which allowed various lengths to be extended so that the treatment area can be changed as required.
• the usual test mandrels are steel drill rod.
• a thermoregulator and quartz heater were employed in order to obtain accurate heating and temperature control.
• the anodes are lead alloys. Chromium acid etch solutions can use stainless steel while iron plating solutions can use iron or steel counter electrodes.
• the drill rod test samples were of several types.
• the F steel rod exhibited adequate adhesion when a chromic acid containing etching solution was used in accordance with the present invention, whereas the VP steel rod exhibited only very poor adhesion when etch alone was used. Adequate adhesion was attained only when the etching was used in combination with the iron electrodeposit pretreating step.
• a metal substrate was plated with iron using a bath containing 200 g/l Copperas, 30 g/l boric acid, 10 ml/l sulfuric acid and 20 g/l of 48% fluoboric acid.
• the metal substrate was prepared using a sandblast treatment followed by an Ajax brand scouring powder scrub, a water rinse, an alkaline dip, a water rinse and drying.
• the 4340 steel substrate Prior to the iron plating, the 4340 steel substrate was etched in cold sulfuric acid at 2 asi for one minute.
• the iron plating was carried out at 2 asi for one minute and 0.5 asi for 10 minutes at 57 degrees C., followed by a water rinse.
• An anodic treatment in a 400 g/l chromic acid bath was carried out at 60°C and 4 asi for 2 minutes.
• the chromium plating step employed a 400 g/l chromic acid, 16 g/l bromate and 64 g/l acetic acid bath. An adequate bond was attained.
• Example 1 The procedure of Example 1 was followed, except that the iron plating at 0.5 asi was for twenty minutes at 63oC. followed by a water rinse. The anodic treatment was carried out for four minutes. An adequate bond was attained.
• a 1010 steel substrate was prepared as previous described and plated in a 485 g/l Copperas, 200 ml/l borax bath at 6 asi for 0.25 minutes and 1.5 asi for one minute.
• the plating bath temperature was 55°C.
• the anodic treatment employed a 150 g/l chromic acid bath at 2 asi for one minute at 57°C.
• the chromic acid bath contained 700 g/l chromic acid, 2 g/l iodide and 4 g/l propionic acid and the treatment was at 4 asi for one hour at 60°C, yielding an adequate bond.
• a 1020 steel substrate was prepared in accordance with the procedure of Example 1 and iron plated at 2 asi for one minute and 1 asi for 3 minutes at 69oC followed by a water rinse.
• the 150 g/l chromic acid anodic treatment bath was maintained at 56oC.
• the treatment was at 2 asi for three minutes.
• the chromium plating employed a 400 g/l chromic acid, 120 g/l monochloroacetic acid, 1 g/l iodide bath at 4 asi for three quarters of an hour. The bath was maintained at 58oC. An adequate bond was produced.
• Example 4 The procedure of Example 4 was followed, except that the F steel substrate was etched in the iron bath at 5 asi for one minute and the iron plating in the iron bath was at 5 asi for three minutes at 63°C.
• the chromic acid plating bath contained 700 g/l of chromic acid, 2 g/l iodide, and 8 g/l of the disodium salt of sulfoacetic acid (Na 2 SAA) .
• the plating was carried out at 4 asi for three quarters of an hour.
• the bath was maintained at 55°C. An adequate bond resulted from the process.
• the substrate was a 4130 steel rod and the iron plating at 61° C was carried out at 5 asi for 0.25 minutes and at 1.5 asi for one minute, followed by a water rinse.
• the anodic treatment bath contained 150 g/l chromic acid at 57°C. The treatment was at 2 asi for one minute.
• the chromium plating bath temperature was 60oC and an adequate bond was produced.
• the iron containing electroplating bath contained 80 grams per liter of FeSO 4 .7H 2 O and 100 milliliters per liter of sulfuric acid.
• the metal substrate was subjected to an anodic treatment for 30 seconds at 0.93 A/cm 2 .
• the chromium plating bath was essentially 300 g/l CrO 3 , 30 g/l Na 2 SAA, 1.5 g/l I, 1.5 g/l SO 4 , at 60oC and required 15 minutes at 0.93 A/cm 2 .
• the resultant chromium plating bond was adequate.
• Example 10 The conditions of Example 10 were employed, except that the iron plating bath additionally contained 10 g/l of CoSO 4 .7H 2 O. The plating produced adequate bond results.
• Example 10 The procedure of Example 10 was followed except that the plating bath additionally contained 20 g/l of CoSO 4 .7H 2 O. The plating produced adequate bond results.
• A/cm 2 to anodically treat the metal substrate followed by cathodic plating at the same conditions.
• the subsequent anodic treatment employed a 150 g/l chromic acid bath at 65oC for 60 seconds at 0.46 A/cm 2 .
• the chromium plating was carried out at 1.24 A/cm 2 for 15 minutes. Inadequate results were obtained.
• Control 2 The conditions of Control 1 were employed except that the anodic, pre-iron plating, treatment was for 10 seconds and no anodic, pre-chromium plating, treatment was employed. The result was inadequate.
• Example 10 The procedure of Example 10 was essentially followed with several exceptions.
• the plating bath additionally contained 5 g/l NiCO 3 , the FeSO 4 concentration was 100 g/l and the chromic acid concentration was 150 g/l in the pre-plate bath.
• the anodic treatment and the plating times and current densities were the same as employed in control 1. However, unlike the control runs, adequate adhesion was obtained.
• Example 13 The procedure of Example 13 was followed except that the NiCO 3 concentrations were, respectively, 10 g/l, 20 g/l and 40 g/l. Adequate adhesion was obtained in each case.
• Example 10 The procedure of Example 10 was followed, except that the iron containing bath was 485 g/l Copperas, 20 g/l borax and 200 ml/I of hydrochloric acid.
• the anodic treatment in the iron plating bath was for 60 seconds at 0.77 A/cm 2 .
• the iron plating was for 15 seconds at 1.0 A/cm 2 and then for 60 seconds at 0.31 A/cm 2 .
• the anodic treatment was for 60 seconds at 0.39 A/cm 2 in a bath containing 800 g/l of chromic acid.
• the chromium plating bath was essentially
• the plating was for 15 minutes at 1.55 A/cm 2 . An adequate bond was obtained.
• Example 17 was followed, except that the substrate was VP steel. An adequate bond was obtained. Control 3
• Example 17 The procedure of Example 17 was followed, except that the iron plating bath was replaced with a Wood's nickel bath having approximately 250 g/l of NiCl 2 .6H 2 O and 125 ml/l of hydrochloric acid.
• the metal substrate was treated anodically in the Wood's bath for 30 seconds at 0.21 A/cm 2 to anodically treat the metal substrate followed by plating for 180 seconds at 0.21 A/cm 2 .
• the next step was to anodically treat the plated metal substrate for 60 seconds at 0.39 A/cm 2 .
• the chromium plating was for 15 minutes at 1.55 A/cm 2 . No bond was obtained.
• Example 17 The procedure of Example 17 was followed, except that the anodic treatment in the iron plating bath was for 60 seconds at 0.08 A/cm 2 .
• the iron plating was carried out for 120 seconds at 1.03 A/cm 2 .
• the anodic treatment was for 60 seconds at 0.39 A/cm 2 followed by the chromium plating for 15 minutes at 1.55 A/cm 2 .
• Example 10 The procedure of Example 10 was followed, except that the iron containing bath contained 100 g/l of Copperas and
• 100 ml/l of sulfuric acid and the substrates were F steel and 1010 steel in Examples 22 and 23, respectively.
• the anodic treatment in the iron plating bath was for 60 seconds at 1.5 A/cm 2
• the iron plating was for 60 seconds at 1.5 A/cm 2
• the anodic treatment was for 60 seconds at 0.37 A/cm 2 and the chromium plating for 15 minutes at 1.49 A/cm 2 . An adequate bond was obtained in each case.
• Example 22 The procedure of Example 22 was followed, except that the iron containing bath further included 50 g/l borax and the chromic acid containing solution in which the iron plated metal substrate was treated anodically, contained 150 g/l chromic acid.
• the iron containing bath further included 50 g/l borax and the chromic acid containing solution in which the iron plated metal substrate was treated anodically, contained 150 g/l chromic acid.
• no pre-iron plating treatment or iron plating was employed.
• Example 25 the anodic treatment in the iron plating bath was for 60 seconds at 1.6 A/cm 2 and the iron plating was for 60 seconds at 1.6 A/cm 2 .
• the pre-chromium plating anodic treatment was at 0.37 A/cm 2 for 120 seconds in Example 24 and for 60 seconds in Example 25.
• the chromium plating was for 15 minutes at 1.49 A/cm 2 . An adequate bond was obtained in each case illustrating that the F steel does not necessarily require the treatments
• Example 29 and in that the chromium bath composition was
• Example 26 the pre-iron plating, treatment step and the iron plating steps were omitted.
• Example 27 the pre-chromium plating treatment step was omitted. In each case the anodic treatment in the iron plating bath was for 60 seconds at 1.55 A/cm 2 , and the iron plating was for 60 seconds at
• Example 29 60 seconds.
• the chromium plating was for 15 minutes at 0.35 A/cm 2 in Example 26 and for 10 minutes in each of the other Examples.
• the current density was 0.77 A/cm 2 in Examples 27 and 28 and 0.62 in the other Example.
• An adequate bond was obtained in Example 29 but a very poor bond was obtained in Example 26 and a poor bond was obtained in the other two cases.
• the pre-iron plating treatment bath can be any of the commonly employed acid activating baths known to the art.
• any bath of the type of pretreatment baths disclosed in Plating and Surface Finishing by Dini et al, November 1982, pages 63 to 65 and in Chromium Plating by Weiner et al. Finishing Publications Ltd., Teddington, England, 1980, at pages 102 through 104 can be used prior to the iron plating step.
• the time, temperature and bath compositions are not narrowly critical.
• the time and current density must merely be sufficient to achieve the desired result as dictated by the nature of the particular substrate metal which is to be chromium plated.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
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• Electroplating Methods And Accessories (AREA)
• Electroplating And Plating Baths Therefor (AREA)
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• Nonmetallic Welding Materials (AREA)
• Polymerisation Methods In General (AREA)
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• Chemical Treatment Of Metals (AREA)
• Application Of Or Painting With Fluid Materials (AREA)

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• 1983
  • 1983-02-03 US US06/463,465 patent/US4450050A/en not_active Expired - Fee Related
• 1984
  • 1984-02-01 WO PCT/US1984/000158 patent/WO1984003109A1/en active IP Right Grant
  • 1984-02-01 EP EP84901037A patent/EP0137817B1/en not_active Expired
  • 1984-02-01 IN IN96/DEL/84A patent/IN160454B/en unknown
  • 1984-02-01 DE DE8484901037T patent/DE3468442D1/de not_active Expired
  • 1984-02-01 JP JP59501013A patent/JPS60500873A/ja active Granted
  • 1984-02-02 ZA ZA84794A patent/ZA84794B/xx unknown
  • 1984-02-02 GR GR73687A patent/GR81725B/el unknown
  • 1984-02-02 ES ES529411A patent/ES529411A0/es active Granted
  • 1984-02-02 PT PT78057A patent/PT78057B/pt unknown
  • 1984-02-03 NZ NZ207033A patent/NZ207033A/en unknown
  • 1984-02-03 IT IT1984A09333A patent/IT8409333A1/it unknown
  • 1984-02-03 IT IT09333/84A patent/IT1198780B/it active
  • 1984-02-03 PH PH30200A patent/PH20218A/en unknown
  • 1984-02-04 EG EG79/84A patent/EG16172A/xx active
  • 1984-10-02 NO NO843974A patent/NO843974L/no unknown
  • 1984-10-02 NO NO843973A patent/NO843973L/no unknown

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