Electrodeposition of a Pd-Ni/TiO2 Composite Coating on 316L SS and Its Corrosion Behavior in Hot Sulfuric Acid Solution
Pd-Ni/TiO2 composite coatings were elaborated on 316L stainless steel by an electrodeposition method. The specimens were obtained from an electrolytic bath that contained various contents (5, 10, and 15 g L&minus;1) of nanosized TiO2 particles. X-ray diffraction (XRD) characterization showed that increasing the TiO2 content in the coatings can decrease the crystal grain size. The surface morphology and chemical composition of the composite coatings were modified by the addition of TiO2 particles in the electrolyte, as shown by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) methods, respectively. The TiO2 content also significantly affected the mechanical and electrochemical properties of the Pd-Ni/TiO2 composite coatings. The microhardness of the Pd-Ni/TiO2 composite coatings can be enhanced by increasing the TiO2 content in the coatings. With the addition of 5 g L&minus;1 TiO2 particles to the electrolyte, the deposited Pd-Ni/TiO2 composite coating presented a remarkably increased corrosion resistance when exposed to a sulfuric acid solution at 60 &deg;C compared with that of the Pd-Ni alloy coating. Nevertheless, the further addition of TiO2 particles into the electrolytic bath did not further improve the corrosion resistance of the composite coating.