Structure and tribo-mechanical properties of Si- and W-containing amorphous carbon based multilayers

• Main Authors: Wolfgang Tillmann, Nelson Filipe Lopes Dias, Dominic Stangier, Serguei Matveev, Carl-Arne Thomann, Jörg Debus
• Format: Article
• Language: English
• Published: Elsevier 2021-09-01
• Series: Applied Surface Science Advances
• Subjects: Amorphous carbon; Silicon; Tungsten; Multilayer; Magnetron sputtering, Raman scattering spectroscopy; Soft x-ray emission spectroscopy
• Online Access: http://www.sciencedirect.com/science/article/pii/S2666523921000519

Designing the film architecture of amorphous carbon based systems is effective in tailoring the tribo-mechanical properties. For this purpose, alternating a-C and a-C:X layers, with X = Si or W, were grown with a layer ratio of 1, a bilayer period of ~200 nm, and a bilayers number of 5 in a magnetron sputtering process. By comparing with a-C(:X) monolayers, the structure and tribo-mechanical properties of alternating a-C/a-C:X films were evaluated.Although the bonding state of the a-C network of a-C:X in a-C/a-C:X is comparable to monolayered a-C:X, the multilayer design significantly affects the tribo-mechanical properties. The a-C/a-C:X multilayers exhibit a higher hardness compared to a-C:X. With a coefficient of friction of 0.12 ± 0.01, a-C/a-C:Si shows a low friction as a-C:Si with 0.09 ± 0.01, but the wear rate is significantly lower for a-C/a-C:Si with (3.4 ± 0.7) × 10-7 mm³/Nm than a-C:Si with (8.3 ± 1.0) × 10-7 mm³/Nm. Contrarily, a-C/a-C:W and a-C:W provide similar wear rates of 1.2 to 1.4 × 10-7 mm³/Nm, but the coefficient of friction is lower for a-C/a-C:W with 0.29 ± 0.02 than a-C:W with 0.36 ± 0.01. Hence, the multilayer design is efficient in improving the tribo-mechanical properties of a-C:X based films.