Pulsed Laser Deposition of ceramics and diamond like carbon on PMMA for tribological applications

The thin films (thickness 400 nm - 3 mum) were deposited by Pulsed Laser Deposition (KrF-Excimer laser, lambda = 248nm, tau = 25ns) with variation of the processing parameters gas pressure, target-to-substrate-distance and laser fluence on the target. Polymethylmethacrylate (PMMA) was chosen as substrate material and the selected coating materials are alumina (Al2O3) and diamond-like-carbon (DLC). The focus in this work is on the adherence of the coatings. Therefore, different pretreatments of the PMMA substrates like plasma processing, deposition of titanium buffer layer, mechanical and chemical surface modification were performed. The hardness and the elastic modulus of the films are measured by nano-indentation. The thickness of the ceramic deposited films are determined by ellipsometry. X-ray photoemission spectroscopy, optical and electron microscopy are used for the determination of the structural and chemical characteristics of the films.