Method for deposition of chromium layers as hard-chrome plating, electroplating bath and hard-chrome surfaces
AssigneeFraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
InventorsJens Bohnet, Martin Metzner, Herwig Krassnitzer, Karl Schermanz
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Abstract
The invention relates to a method for deposition of chromium layers as hard-chrome plating for protection against wear or corrosion and/or for decorative purposes and also an electroplating bath with which chromium layers of this type can be deposited. The invention also relates to hard-chrome surfaces produced accordingly.
Claims29
Method for deposition of chromium layers as hard-chrome plating for protection against wear or corrosion and/or as decorative chrome plating, in which a part is connected as a cathode and is immersed in a catholyte comprising at least one chromium(III) salt and at least one compound stabilizing chromium(II) ions, an anolyte comprising a Brönsted acid is used, catholyte and anolyte being separated by an anion-selective membrane, and also, by means of at least one measuring device, deviations in the pH value from a predefined pH value are monitored continuously and, by means of at least one control device, the pH value is adjusted to the predefined value by automated addition of an acid or a base.
Electroplating bath for deposition of chromium layers as hard-chrome plating for protection against wear or corrosion and/or as decorative chrome plating having a catholyte comprising at least one chromium(III) salt and at least one compound stabilizing chromium(II) ions, an anolyte comprising a protonic acid, catholyte and anolyte being separated by an anion-selective membrane, and also at least one measuring device for continuous monitoring of deviations in the pH value from a predefined pH value and at least one control device for adjusting the pH value to the preset value by automated addition of an acid or a base.
Dependencies are inferred from the claim text.