Corrosion resistance and electrical conductivity of plasma nitrided titanium

The continuous and dense Ti-N compound layers with a thickness ranging from 0.7 to 2.1 mm were formed on the titanium by plasma nitriding at 700 degrees C for different times with hollow cathode discharge assistance. Scanning electron microscope (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to characterize the nitrided layer. XRD and XPS results showed that the compound layer was mainly composed of Ti2N phase. The corrosion current density of 4 h nitrided titanium was 0.016 mA/cm(2) (cathode) and 0.03 mA/cm(2) (anode), respectively. The electrical conductivity of samples was evaluated by means of the interfacial contact resistance (ICR). The value of 4 h nitrided titanium was 4.94 mU-cm(2) which was much lower than that of original titanium 26.25 mU-cm(2) under applied force of 150 Ncm(-2) after corrosion test. The results showed that the electrical conductivity and corrosion resistance of the titanium bipolar plates (BPs) were apparently improved with the formation of Ti2N compound layer. (C) 2020 Publications LLC. Published Elsevier Ltd. All reserved.