Transparency, wettability, and tribological properties of amorphous hydrogenated carbon films deposited on PMMA by RF-PECVD

Abstract

Amorphous hydrogenated carbon (a-C:H) thin films have been deposited on polymethylmethacrylate (PMMA) substrates by radio frequency plasma-enhanced chemical vapor deposition (RF-PECVD) at 13.56 MHz using a mixture gas of acetylene and argon. The influence of the deposition conditions on the transparency, wettability, and tribological properties of the a-C:H films are investigated by UV-Visible spectrophotometry, water contact angle measurement, and ball-on-disk tribometry, respectively. The optical transmittance of the samples decreases as the RF power and deposition pressure increase but it is not affected by changes in the bias voltage. The water contact angle results demonstrate that the wettability of PMMA samples can be improved by varying the bias voltage and RF power during the plasma deposition process. Our studies on the tribological properties indicate that a-C:H films deposited using the suitable bias voltage and high gas pressure exhibit better wear resistance compared to the PMMA substrate.