Preparation of Adhesive Carbon Film on Cu Substrate by Electro-Oxidation of C2 − 2 in a LiCl-KCl-CaCl2-CaC2 Melt

Abstract

Deposition of carbon film on copper substrate with and without electroplating Ni coating by a two-stage potentiostatic electro-oxidation of acetylide anion in a LiCl-KCl-CaCl2-CaC2 melt at 823 K. The results indicated that the carbon deposits obtained on the Ni-coated was continuous and tenacious film due to the high solubility of C in Ni, while that obtained on the bare copper emerged a poor adhesion to the substrate with few carbide or solid solution formation. The cyclic voltammetry for a copper electrode showed that C2 − 2 ions are oxidized more favorably than on graphite electrode, that is due to the active Cu surface can play a catalytic role for oxidation reaction of acetylide ions. However, the catalytic effect of copper will decline when the surface was covered by carbon deposits. By surface modification with electroplating nickel on the Cu substrate, the coarse appearance of Ni coating composed of the small and spherical grains probably helps to the nucleation and growth of carbon film with graphitized and amorphous phases. Meanwhile, the coated Ni interlayer can enhance adhesion of carbon film to copper substrate according to scratch test results and probably protect metallic copper form the anodic dissolution in some extent.