Increasing electrochemical behavior of Ni nanostructure coating with adding SiC nanoparticles by electrodeposition method

In this study, nickel (Ni) nanostructure coating and Ni/SiC nanocomposite coating were produced by electroplating method under pulse current on the stainless steel substrate. The presence of SiC nanoparticles in the Ni matrix caused a change in the preferred orientation from the (200) plane to the (111) plane. This caused the surface morphology of the Ni/SiC composite coating to change from a pyramidal structure to a cauliflower. The electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests were carried out after 1 h in 3.5% NaCl solution. Electrochemical resistance of these coatings was conducted by Solarton-SI1287 potentiostat/galvanostat device. The results of polarization showed that due to the presence of SiC ceramic nanoparticles on the surface of the coating, the corrosion resistance increased by reducing the active metal surface. This was attributed to the neutral nature of the ceramic particles in the corrosive solution. Polarization data was analyzed by CView software. The polarization resistance for the composite coating increased by ⁓ 61 % compared to pure nickel. Also, the corrosion rate for composite coating compared to pure Ni decreased from 0.057 to 0.017. In order to confirm the polarization results, the EIS test was performed. Nyquist curves showed that the area under curve for the composite sample is more than the pure Ni sample. The Bod and phase diagrams also confirmed that. The results obtained from the EIS data were analyzed by Zsimp software. The results obtained from EIS are in good agreement with the data obtained from polarization. Another mechanism that can increase the corrosion resistance of nanocomposite coating is the high electrical conductivity of SiC particles, which reduces the possibility of cathodic reaction on the surface and prevents the formation of galvanic cells. Also, SiC particles act as hole fillers and physical barriers and prevent the penetration of corrosive liquid as much as possible. On the other hand, (111) plane has a higher atomic density than (200) plane. Therefore, another factor that can improve the corrosion resistance in the composite sample is the preferential orientation of the crystal plane (111). The microhardness test was performed by the Olympus Future-Tec FM-700 device for both samples. The results showed that the hardness of the composite sample is higher than the pure sample. The reason for this, according to the Hall-Patch relationship, can be attributed to the reduction of the grain size of the composite coating from 35 to 22 nm. SEM analysis was performed by MIRA3 device equipped with EDS. XRD analysis was done by D8 advanced Bruker device, in order to identify the phase and crystal structure.