Physical Insights into the Effects of Current Parameters on Internal Stress of Ni Electrodeposits

The flatness of precision electroformed components is critically influenced by the internal stress developed in the electrodeposits. This study investigated the influence of current parameters on internal stress in nickel electrodeposits and revealed the corresponding stress regulation mechanism. Nickel electrodeposits were prepared at different current parameters. Physical insights into the effects of Ni electrodeposit properties on internal stresses were analyzed via transmission Kikuchi diffraction and transmission electron microscopy. An inverse relationship was observed between the internal stress and dislocation density. Under the current density from 1 to 5 A/dm2, the dislocation density showed a decrease of 40.9%, while the internal stress increased from 136.0 to 169.7 MPa. Finally, a segmented electroforming process was provided to manufacture nickel molds with high flatness and precise features. This study provided deep insights on the formation mechanism of internal stress in nickel electrodeposits and the strategy to electroform precision components with a high thickness and flatness.