Effect of Process Gas Flow on the Coating Microstructure and Mechanical Properties of Vacuum Kinetic-Sprayed TiN Layers

TiN films were fabricated on glass substrate by a vacuum kinetic spray method to investigate the effect of process gas flow rate, which determines particle velocity, on coating microstructure, and the mechanical properties of the resultant films. The as-fabricated microstructure of the films was studied by x-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy (TEM), and high resolution TEM. Furthermore, nanoindentation and scratch tests were conducted to measure microhardness and adhesion strength, respectively. As the gas flow rate increased, damage, including lattice collapse and distortion, internal dislocation activation, and amorphization of the coating layer, increased. Simultaneously, the film not only become more compact with relatively finer grains, but also showed high hardness and great adhesive strength, which we attributed to consolidation during the deposition process.