Abstract: Based on the theory of two-step reduction of cupric ions in copper electrodeposition, a novel abrasive method is proposed for the abrasive-assisted copper electroforming process to make mechanical friction in sulfate solution bath. A cathode mandrel is employed to revolve in horizontal type, and the cathode basket is filled with moderate non-conductive free beads. Additionally, an offset anode is just fitted on the upper side corresponding to the area without free beads. During the electrodepositing process, for the lower electric field intensity with nonconductive free beads shielding the lower semicircle surface of the mandrel evenly, the copper ions deposit firstly on the cathode area facing the anode, and then the nonconductive and the hard beads are forced to continuously and slightly polish the coverage area on cathode surface. Consequently, the abrasive-assisted electrodeposition process is improved and the quality of the electroformed layer is improved，refraining from the burrs. The result shows that the copper ions are electrodeposited firstly by the theory of two-step reduction of cupric ions with offset anodes, and then the deposits are polished in the copper electrodeposition process. Moreover，a smooth-surfaced electroformed copper layer prepared in an abrasive-assisted way at low speed is achieved from sulfate acid bath without additives, which microstructure had been effectively modified. The grains are also refined at the same time. The microhardness of the electroformed layer is up to 139 HV, and the tensile strength is about 333 MPa at a revolving speed of 5 r/min. When insoluble anode is employed, the mechanical property of the coating is improved significantly. Eventually, a copper electroformed layer with tensile strength of 460 MPa is produced.

Key words: eletro-chemistry engineering, copper electroforming, mechanical property, abrasive-assisted, offset anode