Magnetron sputtered titanium nitride thin films on thermoplastic polymers

Abstract Enhancing the durability of thermoplastic polymers is desirable for improved wear resistance (rubbing, scratching, impact) of plastics in particle sensitive environments. In this investigation poly(butylene terephthalate) (PBT), poly(amide)6.6 (PA) and poly(carbonate) (PC) were chosen as substrate material. The selected coating material was titanium nitride (Ti–N), which is known as wear resistant coating in various applications like drilling and for other machining tools demanding highly durable surfaces. The Ti–N thin films were mainly deposited by magnetron sputter ion plating (MSIP) with different plasma pre-treatments to improve the adhesion. Therefore, it was necessary to vary different parameters of the plasma pre-treatment process, like the etching gas pressure, the r.f. etching power and the etching time, as well as parameters of the deposition process. Based on these investigations the influence of important MSIP process parameters on the deposition rate and mechanical properties was analyzed. It will be shown that in the reactive MSIP mode, deposition rates up to 5 μm/h are attainable (film thickness up to 3.5 μm) in a laboratory plant (Leybold Z 400). Coatings deposited on steel substrates and hard metals were used as references. The influence of selected process parameters (e.g. deposition rate) on the microstructure and the attainable film thickness, from which the deposition rate was deduced, were analyzed by scanning electron microscopy (SEM).