Electroforming of copper by the periodic reversal process

Abstract

Electroforming is one of the lining methods commonly used for depositing copper on accelerator components. In direct current (dc) processes, organic additives are used to obtain a smooth surface. However, additives reduce the purity of the deposit and cannot be applied to accelerator components. The periodic reversal (PR) process produces superior levelling and structural uniformity in the deposits made without additives. The objective of the present work was to study the effect of process parameters (without additives) on the microstructural characteristics and mechanical properties of the electroformed copper. Electroforming with PR eliminated passive interfaces in the deposit, which otherwise developed with dc. Current density during PR was found to have a great influence on the texture of the deposit. Electroformed copper made by PR with a current density of 2 A dm−2 exhibited significantly lower ductility and higher yield stress than that of annealed oxygen-free high conductivity copper (OFHC); this is attributed to its strong (111) texture. The PR process could be continued for long periods and produced negligible roughness.