Structure and mechanical properties of W–Se–C/diamond-like carbon and W–Se/diamond-like carbon bi-layer coatings prepared by pulsed laser deposition

Bi-layer W–Se–C/diamond-like carbon (DLC) and WSex/DLC coatings were obtained by standard and shadow-masked pulsed laser co-deposition from WSe2 and graphite targets. W–Se–C coatings appeared as nanocomposites containing quasi-amorphous WSe2, WC, spherical β-W nanocrystalline particles encapsulated in WSe2 amorphous shell, and amorphous carbon phases. In WSex/DLC coatings, the formation of chemical bonds between W and C atoms was noticed at the interface. An increase of the C concentration over 40 at.% increases hardness and elasticity (up to 2 times at ~ 60 at.%C), and the Se/W ratio was always close to 1.4. The use of shadow-masked configuration avoids the deposition of micro- and nanoparticles. However, this method leads to a substantial increase of the Se content (Se/W ≥ 4), and the coatings became softer.