Corrosion resistance of electrodeposited RE-Ni-W-P-SiC-PTFE composite coating in phosphoric and ferric chloride

Corrosion rate and anode polarization curves of electrodeposited RE-Ni-W-P-SiC-PTFE composite coating in various concentrations of phosphoric and ferric chloride were researched. The results show that corrosion rate of the composite coatings increases with the increasing concentrations of phosphoric and ferric chloride, and reaches the maximum value when phosphoric concentration is 40% and ferric chloride concentration is 20% (mass fraction, the same below if not mentioned). Anode polarization curves of the composite coatings show that anode polarization current density of the composite coatings heat-treated at 200 °C or 500 °C is lower than that of other coatings heat-treated at 300 °C or 400 °C, which displays that the composite coatings heat-treated at 200 °C or 500 °C have better corrosion resistance. Besides, corrosion resistance of the composite coating heat-treated at 500 °C is better than that as deposited and RE-Ni-W-P-SiC composite coating heat-treated at 400 °C, and is also better than that of 316L stainless steel.