Ultrasound-Assisted Deposition of Titanium Nitride Nanoparticles and Electronic Structure of Ideal Contacts

Titanium bipolar plates require surface modification to balance corrosion response and electrical contact resistance. Presynthesized TiN nanoparticles were deposited on Ti by ultrasonic-assisted electrophoretic deposition. In an illustrative comparison of one SEM field per condition, the ultrasound-assisted deposit (40 kHz) showed fewer dark defects: 0.45 versus 2.97% without ultrasound. Five local thickness measurements in one cross section gave 37.58 ± 1.81 μm. XRD supported retention of crystalline TiN, while XPS showed a chemically mixed surface consistent with the preparation history. Room-temperature polarization and impedance measurements in 0.5 mol L–1 H2SO4 + 2 mg L–1 F– showed a potential shift from approximately −0.45 to −0.35 V versus SCE and a higher impedance for the ultrasound-assisted specimen relative to the nonultrasound specimen. Initial gold-contact resistance was approximately 3.2 mΩ cm2 at 1.4 MPa, compared with 4.1 mΩ cm2 for bare Ti. These curves illustrate the tested specimens. Independently, calculations of ideal Ti/TiN contacts resolved registry- and termination-dependent electronic distributions and local Ti–N interactions. The study provides an experimental case for ultrasound-assisted particle assembly and a separate electronic reference for Ti/TiN contact design.