Erosion-corrosion behavior of Pd–Co and Pd–Cu films on 316L stainless steel in simulated PTA slurry environment

Abstract Pd–Co films with the Co content varying from 21.9% to 34.62% (mole fraction) and Pd–Cu (5% Cu, mole fraction) film were electrodeposited on 316L stainless steel, and the erosion-corrosion resistance of the Pd–Co and Pd–Cu plated samples in a simulated boiling pure terephthalic acid (PTA) slurry environment was studied with methods of mass loss test, polarization measurement and scanning electron microscopy (SEM). Under the static state condition, both the Pd–Cu and Pd–Co plated samples exhibit good corrosion resistance and the Pd–Cu film behaves slightly better. However, with increasing the stirring speed, the corrosion rate of the Pd–Cu plated samples increases obviously while that of the Pd–Co plated samples shows only slight increase. Higher microhardness and lower surface roughness of Pd–Co film than those of Pd–Cu film, as well as good corrosion resistance, may be the main reasons for better erosion-corrosion resistance in the strong reductive acid plus erosion environment.