Transactions of Nonferrous Metals Society of China
JOURNAL OF RAILWAY SCIENCE AND ENGINEERING
|Vol. 18 No. 5 October 2008|
（College of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract:The cyclic voltammetry and chronoamperometry were used to study the influence of SiC particles on the nucleation and growth of nickel deposition on copper matrix from acid sulphate solution. The surface morphology of Ni-SiC co-deposition at initial stage was observed with scanning electron microscope(SEM). The results show that the nickel co-deposition with SiC particles may begin at −700 mV (vs SCE) under the experimental conditions, and the nucleation/growth mechanism of Ni-SiC co-deposition tends Scharifker—Hill with three-dimension model. In the case of low over-potential of −710−−740 mV, the nucleation process of Ni-SiC co-deposition may follow the progressive nucleation mechanism of Scharifker—Hill. During higher over-potential of −770−−800 mV, it trends to follow a 3D instantaneous nucleation/growth mechanism. With the increase of over-potential, the relaxation time tm, corresponding to the peak current Im of Ni-SiC co-deposition decreases regularly and is shortened apparently, compared with that of pure Ni deposition. The observation with SEM confirms that SiC particles can be considered as favorable sites for nickel nucleating. When certain amount of SiC particles are adsorbed (or cover) on cathode surface, especially under the condition of high over- potential, they may represent an external inhibition of the nickel electron deposition.
Key words: Ni-SiC film; electron crystallization nucleation; co-deposition mechanism; I—t curve