Physical, structural and mechanical characterization of Ti1-xSixNy films

Abstract

Within the frame of this work, Ti1-xSixNy hard coatings with 0<=x<=0.37 and thicknesses ranging from 1.2 to 3.5 [mu]m, were prepared by r.f. reactive magnetron sputtering in an Ar/N2 gas mixture. X-ray diffraction and Fourier analysis of X-ray profiles were used to investigate the structure and grain size, and its correlation with hardness behaviour, as a function of the Si content, bias voltage and working gas (argon) flow rate. In this respect, the results show that a double cubic phase of NaCl type was developed with lattice parameters of 4.18 and 4.30 Ã…, revealing the (111) orientation for low Si content (x=0.05), (220) for intermediate Si contents (0.13<=x<=0.22) and (200) for the highest Si contents (0.30<=x<=0.37). Regarding the results of ultramicrohardness tests, and although all samples with 0.05<=x<=0.30 present a hardness value higher than 30 GPa, the Ti0.85Si0.15N1.03 revealed the highest hardness value, around 47 GPa, which is more than twice as high as that of common TiN. Furthermore, the study of hardness as a function of the applied bias voltage revealed that best results are achieved between -50 and 0 V. The variation in hardness as a function of the argon flow showed that best results in hardness are obtained when working with flow rates around 110 cm3/min.