Experimental study on the microstructural and anti-corrosion behaviour of Co-deposition Ni-Co-SiO2 composite coating on mild steel

Mild steel is commonly used in the construction of Pipeline. The major problem of this Pipeline is corrosion. Effort is make my researchers to combat this problem. In this work Co-deposition of Ni-Co-SiO2 composite coating on mild steel was reported with the view to reduce this problem. The SiO2 was varies from 5 to 25wt% in the deposition. The microstructure, hardness values and potentiodynamic polarization in simulated sea water were determined. The results show that XRD pattern of the NiCo deposited mild steel revealed the presence hard phases of NiO, Co5Ni, Co2Ni3, NiCo5 while that of Ni-Co-SiO2 deposited mild steel revealed the presence harder phases of NiOSiO2, CoNi7Si2, Co5Ni2Si3. The NiCo-25SiO2 deposited sample has smaller particle size than Ni-10Co coating. Coating thickness of 110.7 μm was obtained for Ni-10Co coating, while coating thickness of 135.7, 157.7, 165.0 μm were obtained at Ni-10Co-xSiO2(x = 10, 15, 25wt%). 99.90% corrosion resistance was achieved at Ni-Co-25SiO2. This improvement in corrosion resistance after composites coating could be attributed to the hard and fine structure obtained after coating.