Corrosion Resistance of TiN Coatings Prepared by Filtered Cathodic Vacuum Arc Process

Abstract

ABSTRACTFor the purpose of developing the corrosion-resistant and low-cost metallic bipolar plates for direct methanol fuel cell (DMFC), Ti mesh, stainless steel and Si(100) were coated with TiN by using the filtered cathodic vacuum arc system (FCVA). These TiN films have received considerable attention because of its high anti-corrosion behavior and low contact-resistance. In order to improve the corrosion protective ability of TiN films and decrease pinholes of coating, growth modifications such as thickness of the coatings and bias applied to substrates have also been carried out. The microstructures and composition of TiN film were identified by the instrumental analyses such as scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The corrosion behavior of TiN coatings was studied in 0.5 M H2SO4 solutions by using potentiodynamic polarization method. The DC bias of −150 V was applied to the substrates to achieve a dense structure of approximately 400 nm coating of TiN, so that good corrosion protection of the Ti mesh and stainless steel substrates can be achieved. The TiN coating on stainless steel exhibited excellent corrosion behavior especially in lower corrosion current than 2×10−7 A/cm2.