Ti–B–C nanocomposite coatings deposited by magnetron sputtering

Ti–B–C nanocomposite coatings with a B content of 8–17 at.% have been deposited by magnetron sputtering from B4C, Ti, and C targets. X-ray diffraction, photoelectron spectroscopy, and electron microscopy show that the coatings consist of nanocrystalline (nc) TiC:B embedded in a matrix of amorphous (a) C, BCx, TiOx and BOx. The fraction of amorphous phase scales with the Ti concentration, where the matrix predominantly consists of free C with some BCx in coatings with a C/Ti ratio > 1, while the matrix predominantly consists of BCx with some free C in coatings with a C/Ti ratio < 1. nc-TiC:B/a-BCx/a-C coatings with low amount of free C exhibit a contact resistance comparable to the contact resistance of an Ag sputtered coating at loads of ∼1 N against an Au probe, despite the O content of ∼16 at.%.