Bias voltage effect on the structure and property of the (Ti:Cu)-DLC films fabricated by cathodic arc plasma

Titanium copper–diamond-like carbon (Ti:Cu)-DLC films were deposited onto silicon via cathodic arc evaporation process using titanium (Ti) and copper (Cu) target arc sources to provide Ti and Cu in the metal containing diamond-like carbon (Me-DLC) film systen. Acetylene reactive gases served as the carbon sources, which were activated at 180 °C at 20 mTorr. Varying substrate bias voltages from − 80 to − 250 V were used in order to provide the (Ti:Cu)-DLC structure. The structure, interface, and mechanical properties of the produced film were analyzed by transmission electron microscope (TEM), IR Fourier transform (FTIR) spectra, and Rockwell C hardness. The process parameters were compared by studying the various mechanical properties of the films, such as microhardness and adhesion. The results showed that the Ti-containing a-C:H/Cu coatings exhibited an amorphous layer of Ti-DLC layer as well as a nanocrystalline layer of Cu multilayer structure. The mechanical properties of the coatings, as determined by Rockwell C indents testing and the ball-on-disc test, varied with the the applied negative DC bias voltage. These (Ti:Cu)-DLC coatings are promising materials for soft substrate protective coatings.

Research Highlights
► (Ti:Cu)-DLC films were deposited on 7050 Al alloy using a Ti cathode and a Cu cathode by cathodic arc plasma deposition method.
► The films had a multilayered structure, where nanocrystalline Cu layers alternated with amorphous Ti-DLC layers.