Transparent abrasion resistant coatings on plastic and metal substrates

Plastic and metal materials have different but excellent and valuable properties. For spreading to more applications harder surface resulting in improved abrasion resistance without essential changing of optical properties is requested. Transparent oxide layers on large area substrates like plastic films and sheets and metal foils and sheets can be deposited by high rate plasma activated deposition technology with high productivity. Application of HAD (Hollow cathode arc Activated Deposition) process with EB evaporation of silicon dioxide and organic modification of layer material by introduction of monomer in the evaporation process results in excellent adaptation of oxide layer properties to plastic and metal substrates as well. Despite the low condensation temperature requested for plastic materials, the plasma activation results in dense and glassy amorphous layers. The layer hardness on plastic substrates ranges between 2 to 3 GPa. Organic modification results in improved elasticity essential for crack-free performance of layers despite the strong mismatch in thermal expansion coefficient. Coating of metal substrates gives much more freedom for process parameters. With higher substrate temperature and much higher degree of plasma activation the SiOx layer hardness can be improved to 15 GPa. Absorption coefficient can be kept low for whole hardness range