Monday, March 7, 2011

Chromium Plating As Patent

  1. A plating bath for electroplating various metals with chromium, consisting essentially of the composition resulting from the combination of 100-1600 g/l of chromium trioxide and one or more of the following:
    • 0.3-15 weight % Cl or Cl.sup.- based on the chromium trioxide, and
    • 0.5-10 weight % I or I.sup.- based on the chromium trioxide.
  2. A plating bath in accordance with claim 1 in which no sulfate has been added.
  3. A plating bath according to claim 2, wherein said composition results from the combination of from 250 to 500 g chromium trioxide and from 2.5 to 10 weight percent of Cl or Cl.sup.- calculated on the chromium trioxide.
  4. A plating bath according to claim 2, wherein said composition results from the combination of from 250 to 1000 g chromium trioxide per liter water and from 1 weight percent to 10 weight percent I or I.sup.- calculated on the chromium trioxide.
  5. A plating bath according to claim 2, wherein said composition results from the combination of from 250 g to 1000 g chromium trioxide per liter water, from 0.3 weight percent to 10 weight percent Cl or Cl.sup.- calculated on the chromium trioxide and 0.3 to 10 weight percent I or I.sup.- calculated on the chromium trioxide.
  6. A plating bath in accordance with claim 4 or 5, wherein the I or I.sup.- is added as HI, HIO, HIO.sub.2, HIO.sub.3, HIO.sub.4, KI, KIO.sub.3, or NaI.
  7. A plating bath in accordance with claim 5, wherein the Cl or Cl.sup.- and the I or I.sup.- are added as Cl I or ICl.sub.3.
  8. A plating bath according to claim 1, wherein the amount of chromium trioxide combined to result in said composition comprises from 250 to 1000 g chromium trioxide per liter water.
  9. A plating bath according to claim 8 wherein said composition results from the further inclusion of from 0.3 to 2 weight percent sulfate ions calculated on the chromium trioxide.
  10. A plating bath according to claim 1, wherein the constituents Cl, Cl.sup.-, I and I.sup.-, when present, are chosen from the group consisting of HCl, HI, HIO, HIO.sub.2, HIO.sub.3, HIO.sub.4, KCl, KI, NaCl, KIO.sub.3, NaI, MgCl.sub.2, CrCl.sub.3, ClI, and ICl.sub.3.
  11. A process for electroplating with chromium wherein the electroplating is effected in a plating bath according to claim 1, at a temperature from ambient temperature to a temperature of 60.degree. C., at a current density of from 10 A/dm.sup.2 to 270 A/dm.sup.2.
  12. A process according to claim 11, wherein the electroplating is effected at a current density from 30 to 250 A/dm.sup.2 and at 25.degree. C. to 50.degree. C.
A process for electrodeposition of both hard and if desired bright chrome platings with high current efficiency and plating baths for carrying out such electroplating process.

The plating bath comprises as main constituent chromium trioxide, which is used in combination with proper quantities of chlorine or its ions and/or iodine or its ions optionally with a small quantity of sulfate ions.

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