Transparent plastics, e.g. PMMA or Polycarbonate, have low weight, optical clarity and processing benefits of a thermoplastic. A great disadvantage of such plastics is the lack of abrasion resistance. Therefore the plastics have to be protected for practical application. SiO{sub}2 layers perform very well as clear abrasion resistant layers. The typical layer thickness ranges from 1 μm to 6 μm depending on the required abrasion resistance. To get an abrasion resistance comparable to float glass a layer thickness of about 6 μm for SiO{sub}2 layers is needed. The layers are deposited by the FIAD-process (hollow cathode activated deposition). There the coating material is evaporated by an electron beam and is deposited on the substrate by adding reactive gases (e.g. O{sub}2, N{sub}2O or organic monomers) at the presence of an intensive plasma. A special hollow cathode, adapted to this process, is used as plasma source. The typical deposition rates are 300 nm/s to 600 nm/s for the deposition of SiO{sub}2.
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