Vacuum arc deposition of conductive wear resistant coatings on polymer substrates

Thin conductive wear resistant metal/ceramic coatings were deposited onto polysulfone S2010 substrates using a triple-cathode vacuum arc plasma source connected to a magnetized plasma duct. Various combinations of two-layer coatings having an inner metallic conductive layer of Ti, Zr, Cu, Ag or Al attached to the plastic, and an external wear resistant layer of TiN or ZrN, were studied and evaluated. It was shown that bi-layer Ti/TiN and Ti/ZrN coatings had good adhesion to the substrate and low wear rate, but their electrical surface resistivity was high (3-6.6 Ω/[]). Cu, Ag and Al metal sublayers had a superior adhesion to the polymer substrate and low surface resistivity (less then 0.1 Ω/[]). However, the deposition of a TiN layer on Ag caused immediate coating delamination from the substrate. In the case of Ag/ZrN coatings, which initially possessed good adhesion to the substrate, cracking and delamination of ZrN at the Ag/ZrN interface was observed after some time (1-7 days), while the Ag layer remained adherent to the substrate. In the cases of Cu/TiN and Cu/ZrN coatings, the nitride layers had poor adhesion to the Cu layer. The best results were obtained for Al/ZrN coatings, which had low surface resistivity (0.08-0.11 Ω/[]) with good adhesion of the Al layer to the substrate and of the nitride layer to Al.