Effects of Powder Structure on Electrical and Mechanical Properties of Vacuum Cold Sprayed TiN Coatings

Titanium nitride (TiN) coatings on Al2O3 substrates were prepared by vacuum cold spray (VCS) process at room temperature with powder size of 20 nm and 1.6 µm using different spraying parameters. Microstructure characterization and phase analysis were carried out on original particles and deposited coatings by scanning electron microscope and X-ray diffraction. The bonding strength of the VCS TiN coatings was evaluated by scratch test. The sheet resistance and electrical resistivity of the coatings were measured by four-point probe method. The scratch test results showed that the coatings present good adhesion to the substrate and the critical load is 13.3 - 40.1 N. The sheet resistance and electrical resistivity of the TiN coatings deposited with the powder size of 1.6 μm are significantly less than that of the nano-structured coatings. A minimum electrical resistivity of 7.5×10^-5 Ω·m is achieved. The sheet resistance of the VCS TiN coatings can be controlled less than 10 Ω.