Electroplating of metals using pulsed reverse current for control of hydrogen evolution

The method of claim 6 wherein said forward pulses of said pulsed reverse current have a duty cycle of from about 80% to about 90%.

In a method for electrolytic deposition of metals on a cathode substrate by immersing an anode and a cathode in an aqueous plating bath containing metal-bearing ions and passing an electric current between said anode and said cathode, wherein said metal-bearing ions are capable of migrating to said cathode and being discharged at said cathode, and are capable of reacting with hydroxide ions generated in the vicinity of said cathode by evolution of hydrogen at said cathode, the improvement comprising controlling excessive evolution of hydrogen at said cathode by using as said electric current a pulsed reverse current.

A method of depositing a layer of chromium metal on a substrate comprising

• providing an aqueous plating bath containing a water-soluble salt of trivalent chromium;
• immersing in said plating bath a cathode comprising an electrically conducting substrate and an anode;
• passing an electric current between said anode and said cathode wherein said current is a pulsed reverse current having a frequency of from about 5 Hz to about 700 Hz, said pulsed current comprising forward pulses having a duty cycle of from about 25% to about 95%, and reverse pulses having a duty cycle of from about 50% to about 5%, said reverse pulses being interposed between at least some of said forward pulses.