Correlation between plasma particle fluxes, microstructure and properties of titanium diboride thin films

Superhard hexagonal TiB2 coatings with Vickers hardness up to 5000 HV0.015 were deposited on cemented tungsten carbide and silicon substrates by means of d.c. magnetron sputtering. Their microstructure has been studied through X-ray diffraction, X-ray reflectivity and scanning electron microscopy, in relation to the influence of substrate bias during deposition. Combined with an evaluation of mechanical properties of the deposited coatings like residual stress and Vickers hardness, the effects of plasma ion bombardment are presented and discussed. The ion impact during deposition is shown to produce structural densification and crystalline modification. A strongly (0 0 1)-ordered texture is considered as the dominant factor for hardness enhancement.