Hydrogen Desorption and Internal Stress in Nickel Coatings Obtained by Periodic Electrodeposition

Abstract

Periodic electrodeposition is performed in order to determine to whatextent a change in conditions for the desorption of hydrogen from nickeldeposits, which is occluded during plating, can affect their internalstress. The duration of the pause (zero current), tau(off), is varied inthe range 0-900 s and the plating period, tau(on) = 120 s, is keptconstant, maintaining the structure unchanged. The variations ofinternal stress, microhardness, and coercivity of the electrodepositsobtained at different tau(off), are investigated. The amounts ofhydrogen leaving the coating, both during the pauses and after thedeposition is completed, are determined. A proof of the mechanicalnature of intensive hydrogen codeposition at the beginning of nickelelectroplating is obtained. It is shown that the desorption of hydrogenis responsible to a considerable extent for the high tensile internalstress observed in similar coatings.