Preparation of Crystalline Chromium Coating on Cu Substrate Directly by DC Electrodepositing from Wholly Environmentally Acceptable Cr(III) Electrolyte

• Crystalline chromium coating was electrodeposited on copper from Cr(III) electrolyte.
• A wholly environmentally acceptable Cr(III) electrolyte was developed.
• The crystalline coating was produced by DC electrodepositing without heat treatment.
• For the first time the crystalline chromium coating was analysed by TEM and SAED.

Almost all of the currently achievable chromium coatings using Cr(III) electrolytes are amorphous. In this work, a crystalline chromium coating with an attractive appearance was produced on Cu substrates. This was achieved using direct current (DC) electrodepositing of a wholly environmentally acceptable sulfate Cr(III) electrolyte without a subsequent heat treatment. Structural characterization revealed that the crystalline chromium coating deposited at 5 A/dm2 from the electrolyte solution is composed of body-centered cubic (bcc) Cr crystals, which demonstrated significant preferred orientation and a size range of 50–60 nm. The results also show that, in general, the color and luster of the chromium coating are greatly affected by the current density employed, and the larger the current density is, the dimmer the coating.