High-rate deposition of amorphous and nanocomposite Ti–Si–C multifunctional coatings

Amorphous (a) and nanocomposite Ti–Si–C coatings were deposited at rates up to 16 μm/h by direct current magnetron sputtering from a Ti3SiC2 compound target, using an industrial pilot-plant system, onto high-speed steel, Si, and SiO2 substrates as well as Ni-plated Cu cylinders, kept at a temperature of 200 or 270 °C. Electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction analyses showed that TiC/a-C/a-SiC nanocomposites were formed consisting of textured TiC nanocrystallites (nc) embedded in a matrix of a-C and a-SiC. Elastic recoil detection analysis showed that coatings deposited at a target-to-substrate distance of 2 cm and an Ar pressure of 10 mTorr have a composition close to that of the Ti3SiC2 compound target, as explained by ballistic transport of the species. Increased target-to-substrate distance from 2 cm to 8 cm resulted in a higher carbon-to-titanium ratio in the coatings than for the Ti3SiC2 compound target, due to different gas-phase scattering properties between the sputtered species. The coating microstructure could be modified from nanocrystalline to predominantly amorphous by changing the pressure and target-to-substrate conditions to 4 mTorr and 2 cm, respectively. A decreased pressure from 10 mTorr to 4 or 2 mTorr at a target-to-substrate distance of 2 cm decreased the deposition rate up to a factor of ~ 7 as explained by resputtering and an increase in the plasma sheath thickness. The coatings exhibited electrical resistivity in the range 160–800 μΩ cm, contact resistance down to 0.8 mΩ at a contact force of 40 N, and nanoindentation hardness in the range of 6–38 GPa.