| Abstract: | 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. SiO2 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 SiO2 layers is needed. The layers are deposited by the HAD‐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. O2, N2O 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 SiO2. |
