Pulsed laser-deposited composite carbon-glass-ceramic films with improved hardness

A composite material obtained by mixing a glass-ceramic powder and C-60 has been used to obtain thin films by nanosecond pulsed laser deposition technique, with the aim to improve the mechanical properties of the potentially bioactive coatings. Films have been deposited by using a Nd:YAG laser source (lambda = 532, tau = 7 ns, 10 Hz) on titanium substrates heated at different temperatures. The deposited coatings present a sub-micron homogeneous texture completely covering the substrate with micrometric inclusions distributed on the whole surface, as observed by AFM and SEM. IR and XRD spectra of films are characteristic of amorphous calcium silicate materials, suggesting that the carbonaceous component inhibits the glass matrix crystallization, also at high deposition temperatures. Micro-Raman measurements evidence that fullerene transforms into amorphous carbon and reduced graphene oxide (RGO)-like domains in films deposited at room temperature and 500 degrees C, respectively. The presence of the RGO-like domains embedded in the amorphous glassy matrix has been related to the observed improved Vickers microhardness.