Characterization and enhancement of IR optical and tribological properties of DLC films synthesized by RF-PECVD

Taburoğlu, Vahit Eren
This thesis analyzes the hydrogenated amorphous diamond like carbon (a-DLC) films coated on aluminum substrates by the technique of plasma enhanced chemical vapor deposition (PECVD). Effects of film thickness, hydrogen content and RF power on the tribology, optical characteristics and structure are observed and studied in detail. DLC films have compressive intrinsic stresses by default. Surface topography revealed by an interferometer shows that too low/high compressive stress is detrimental to the film. In order to obtain the targeted results in terms of optical reflectivity, hardness, elasticity and durability of the film, one should use a well thought combination of thickness, hydrogen content and RF power in design and production stages. Frictional effects, recovery power (ratio of hardness ([H] to Young’s modulus [E]; namely H/E) and restoration power are studied under a continuous predetermined scratching attack to decide on optimum initial coating conditions. As a promising candidate for superlubricity, DLC films have exceptional hardness and friction coefficient which are core parameters to work on. Film robustness and durability under harsh environmental conditions are other pillars of the study. Furthermore by using XPS, it is proved that sp3/sp2 distribution is not uniform throughout the films, but sp3/sp2 ratio can be increased via some methods like increasing in hydrogen content.