Influence of titanium concentration on mechanical properties and wear resistance to Ti6Al4V of Ti-C:H on cemented carbide

Titanium doped hydrogenated amorphous carbon (Ti-C:H) was synthesized on silicon, YG8 cemented carbide by middle frequency magnetron sputtering technology. Doped Ti concentration was adjusted via allotting Ar/C2H2 flow rate to be 0-1.21 at.%. To investigate the influence of Ti concentration on mechanical properties and wear resistance to Ti6Al4V, stylus profiler, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), nanoindentation, energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM) and ball-on-disk friction test were applied. The results indicated that the incorporated Ti element existed as amorphous-like structure within the carbon network resulting in the decrease of sp3 fraction and increase of graphitization. The compressive stress of the film declined gradually along with the sacrifice of hardness and elastic modulus as the increase of Ti concentration. Compared with the none-doped and 1.21 at.% Ti-C:H, the friction coefficient of 0.32 at.% and 0.74 at.% Ti-C:H remained lower and more stable value of 0.07, which led to a lower wear rate of about 3.1 E-8 mm3/Nm as well. The worn surface of various Ti-C:H films after rubbing against Ti6Al4V exhibited three kinds of morphologies as adhesive wear, smooth and abrasive wear. The different morphologies and wear mechanism were discussed.