Ti–B–C–N and Ti–Si–B–C–N nanocomposite coatings were deposited on AISI 304
stainless steel substrates by DC unbalanced magnetron sputtering from two (80mol% TiB2–20mol%
TiC and 40mol% TiB2–60mol% TiC) composite targets in various Si target powers. The relationship
among microstructures, mechanical properties, and tribologiacal properties was investigated. The
synthesized Ti–B–C–N and Ti–Si–B–C–N coatings were characterized using x–ray diffraction
(XRD) and x–ray photoelectron spectroscopy (XPS). These analyses revealed that the Ti–Si–B–C–N
coatings are nanocomposites consisting of solid-solution (Ti,C,N)B2 and Ti(C,N) crystallites
distributed in an amorphous TiSi2, SiC, and SiB4 matrix including some carbon, BN, CNx, TiO2, and
B2O3 components. The addition of Si to the Ti–B–C–N coating led to percolation of amorphous TiSi2,
SiC, and SiB4 phases. The Ti–Si–B–C–N coatings exhibited high hardness and H/E values, indicating
high fracture toughness, of approximately 35 GPa and 0.098, respectively. Furthermore, the
Ti–Si–B–C–N coatings exhibited very low wear rates ranging from ~3×10-7 to ~16×10-7 mm3/(N·m).
The minimum friction coefficient of the Ti–Si–B–C–N coatings was approximately 0.15 at low Si
target power between 25W and 50W. A systematic investigation on the microstructures, mechanical
properties, and tribological properties of Ti–Si–B–C–N coatings prepared from two TiB2–TiC
composite targets and one Si target is reported in this paper.