Effect of SiC concentration on electrochemical and mechanical behavior of Zn-SiC composite coating

• Published in: Journal of physics. Conference series 2018-08, Vol.1082 (1), p.12064
• Main Authors: Al-Dhire, T M, Zuhailawati, H, Anasyida, A S
• Format: Article
• Language: English
• Subjects: Chromates; Coated electrodes; Corrosion rate; Corrosion resistance; Cross-sections; Diamond pyramid hardness; Electrochemical analysis; Electrode polarization; Electrodeposition; Linear polarization; Low carbon steels; Mechanical properties; Morphology; Particulate composites; Physics; Protective coatings; Silicon carbide; Steel plates; Thickness; Zinc; Zinc coatings
• ISSN: 1742-6588; 1742-6596
• DOI: 10.1088/1742-6596/1082/1/012064

Electrodeposition of zinc with SiC particles is a promising process that could effectively replace chromate process. Increasing of SiC concentration in the bath solution could increase the incorporation of SiC particles into zinc matrix and help in improvement of corrosion resistance and hardness of composite coating. However, it is difficult to obtain composite coating with uniform, dense and high SiC content. The aim of this study to investigate the effect of SiC concentration on electrochemical and mechanical behavior of Zn-SiC composite coating. Zn-SiC composite coatings were successfully deposited on mild steel plate using electrodeposition technique. Zinc sulfate bath containing 2 micron-sized of SiC particles were prepared to deposit the composite coating. The deposition was carried out under operating conditions of current density 40 mA/cm2 and 600 rpm of agitation rate. Various concentrations of SiC (0, 5, 10, 15 and 20g/l) were investigated. Electrochemical behavior of Zn-SiC coating was performed using linear polarization method. The hardness of the coating was carried out using Vickers hardness tester and the measurements were taken through cross section of the coating. Coating thickness and morphology of the coating were examined using SEM. The experimental results observed an improvement in corrosion resistance and hardness of the coating with increasing SiC content. The microhardness value of 166 (Hv) was obtained at optimum concentration of 20 g/l. The corrosion results showed that the corrosion rate of 6.05 x 10−1 mm/yr and 3.0 x 10−1 mm/yr were obtained for Zn (0 g/l of SiC) and Zn-SiC (20g/l of SiC) coatings respectively. SEM images of the surface and cross section of the coating showed an embedding of SiC into zinc coating and its particles were distributed along cross section of the coating. Finally average thickness of the coating was recorded at 19 microns.