On the corrosion characterization of titanium nitride in sulfuric acid solution

The sulfuric acid corrosion behavior of TiN-coating on stainless steel, prepared by plasma enhanced physical vapor deposition (PVD), was studied by using a perforation test, dynamic and static polarizations and open-circuit potential (OCP) measurements. It was found that the corrosion of TiN strongly depended on the concentration of H2SO4. For the range of 0.1-10 N H2SO4, the corrosion rate increased, while for 10-36 N acid, it decreased with the acid concentration. It was also noted that the corrosion rates of 20-36 N acid were much lower than those of 0.1-20 N solution. For 0.1-20 N sulfuric acid, X-ray photoelectron spectra (XPS) accompanied by thermodynamic considerations allowed determination of the chemical states of the corrosion products and the related chemical reactions. For 20-36 N sulfuric acid, a passivation model has been proposed.