Ti(Al/Pt)N films prepared on Ti6Al4V (TC4) plates were soaked in a simulated proton exchange membrane fuel cell (PEMFC) anode environment for three weeks. The dense Ti(Al/Pt)N films exhibited various preferred orientations: TiN and TiAlN films with (111) and TiAl(Pt)N film with (200) orientations. The inner stresses of the Ti (Al/Pt)N films changed from -13 MPa for TiN, -115 MPa for TiAlN, and -66 MPa for TiAl(Pt)N. The corrosion current densities of TiN, TiAlN, and TiAl(Pt)N were of the order of 10-8, 10-7 and 10-6 A center dot cm- 2, respectively. Their corresponding contact resistance values decreased sequentially from 29.85, 15.25 and 9.85 m omega cm2. The appearance of second EIS impedance circles after soaking the films in the simulated PEMFC environment for 3 weeks was indicative of the corrosion failure of the Ti(Al/Pt)N films. The relatively high inner stress in the TiN film led to the formation of oxides and corrosion pits. Peeling of the TiAlN film off the TC4 occurred owing to the high inner stress. The micro-potential difference between the TiAlN columns and Pt particles that were distributed along the column boundary led to the formation of crack networks in the TiAl(Pt)N film. Al/Pt in TiN deteriorated the durability of the films, although it enhanced their conductivity.
NSTL
Elsevier