Nanomechanical and nanotribological behaviors of hafnium boride thin films

Nanocrystalline HfB2, HfBN and multilayer HfB2/HfBN films were deposited using chemical vapor deposition. Half of the amorphous as-deposited films were subjected to annealing at 700°C to obtain their annealed equivalent samples. Nanoindentation and nanoscratch experiments were performed to measure their mechanical properties, friction and scratch/wear behavior. The annealed films showed higher hardness values compared to the as-deposited films, with the HfB2 film exhibiting the highest hardness. All three films exhibited similar shear strength around 3GPa for as-deposited and 5.5GPa for annealed films, implying reduced delamination propensity for the annealed samples. The annealed HfBN and multilayer HfB2/HfBN films exhibited lower friction and wear, compared to the rest of the films. Specifically, the annealed multilayer HfB2/HfBN films, exhibited an order of magnitude lower wear, compared to the HfB2 films, making them excellent candidates for low friction and low wear hard coating applications. •Hard, dense thin films of HfB2/HfBN were deposited using chemical vapor deposition.•Annealed films exhibited high shear strength, and thus reduced propensity to delamination.•Hardness values alone do not correlate with friction and wear performance.•Annealed multi-layered HfB2/HfBN films exhibited outstanding friction and wear resistance.