Transmaterial

Glass-Coated Plastic

Plastics come in many forms. They are used to make boats, magnifiers, skis and all manner of household items. Transparent plastic sheet panels would be ideal in the manufacture of windows or headlamps of cars, for example, and tinted plastic foils could more readily be used to protect against the sun – if only the material was not so easily scratched. Researchers at the Fraunhofer Institute for Electron Beam and Plasma Technology FEP in Dresden have developed a process by which plastic sheet panels and foils can be rapidly coated with a scratchproof glassy layer at moderate costs.

There are various means of applying a transparent scratchproof coating to plastic materials: liquid coatings such as paint or sol-gel applications - or methods such as plasma chemical vapor deposition, sputtering or electron-beam evaporation, whereby the coating is applied in a vacuum. Liquid coatings are relatively inexpensive, but do not ensure such a hard and wear-resistant surface as do vacuum coating processes. High-rate electron-beam evaporation is copmaratively the least expensive vacuum coating process. To achieve coatings of extreme hardness and resilience it is necessary to apply an intensive plasma during the evaporation process. "We evaporate quartz glass, which is then deposited on the plastic surface," explains Dr. Manfred Neumann of the FEP. "The system we use can coat foils or sheets with a width of up to 40 centimeters, but in principle coating widths of several meters are quite possible." The coating speed with plasma-activated high-rate electron-beam evaporation is around 100 times greater than with other vacuum coating processes – applying a thickness of up to a micrometer per second.

Clear and hard glass surfaces of this kind open up new potential applications for plastics – in car windows and headlamps, solar collectors, floor coverings and wall panels. A thin surface coating only six micrometers in depth makes the plastic as wear-resistant as normal glass. The high speed of the process substantially reduces costs – and the greater the volume of plastic coated, the less expensive the job becomes. [Excerpted from the Fraunhofer Institute's website]

posted by Blaine @ 7:25 AM