EFFECT OF ULTRASOUNDS IRRADIATION ON THE ELECTROLYTIC GROWTH OF NANOCRYSTALLINE NI FILMS
The present study reports the effects of ultrasounds irradiation on both charge transfer processes and interfacial structures in acid nickel sulfate electrolytes by various electrochemical methods. Moreover, the surface structure of electrolysis product-Ni film was evidenced by AFM. In order to determine optimum electrolysis parameters, we investigated the current-potential curves (voltammograms) at copper electrode and Ni ion collision speed with Cu substrate for different powers of ultrasonication processes. The bath efficiency has been also studied as a function of the time and the current density applied. The ion collision speed, bath efficiency, the hardness, the brightness and the adherence of the electrodeposits increase with the ultrasonic agitation, in comparison with the same film produced from still or magnetic stirred baths. Surface analyses of Ni films are performed using atomic force microscopy (AFM). Both surface roughness and grain size are the important factors in all areas of nanotribology and in evaluating the quality of a nanostructured surface operation. The results show that there exists optimum ultrasound sonication intensity where the mechanical properties of the Ni films are mostly enhanced. Moreover, results indicate that the grain size of nanocrystalline Ni film change with different sonicating intensity.
Keywords: sonoelectrochemistry, electrodeposition, nanocrystalline film, atomic force microscopy