Glass coatings, process

The glass coating process requires high gas flows for the sputter processes as well as low hydrocarbon concentration. The only vacuum pump which satisfies these requirements as well as high pumping speed stability over time are turbo-molecular pumps which are used almost exclusively. 

Figure 3.12. SEM image of a CuIno.7Gao.3Se2 film deposited using a hydrazine-based spin-coating process. The film is deposited on a 500-nm-thick layer of Mo on a glass substrate.

In this contribution a novel fluidized-bed coating process is introduced to encapsulate heat-sensitive materials with particle sizes below 100 pum. Supercritical carbon dioxide is used as solvent for the coating material as well as carrier fluid for the core material. The behaviour of the high pressure fluidized-bed was investigated for different process parameters and materials. It is shown that the fluidization starts at lower fluid velocities if the pressure is increased and it was possible to fluidized particles with a mean size below 10 xm. The coating of glass beads with stearyl alcohol was carried out and layers with a thickness of 1-8 xm were achieved. 

Metallizers with external unwind and rewind facilities have also become known. Here the web is transported into and out of the vacuum chamber through locks. Because of demanding requirements of instruments and apparatus, these coaters have not gained acceptance for coating of polymer webs. They are successfully used in semi-continuous processes, for example glass coating. 

The pyrolysis of unsymmetrically substituted cyclo-di-QM and the subsequent polymerization of the generated monomers by means of the vapor-coating process has been studied 43 K The pyrolysis gas of acetyl-cyclo-di-QM is initially led through a glass tube maintained at 90 °C and subsequently through another glass tube kept at a temperature of 20 °C. The obtained polymer at 90 °C has been identified as poly-acetyl-QM on the basis of elemental analysis and IR spectrometry. A second pyrolysis process and the subsequent fractional polymerization at the threshold polymer obtained at 25 °C has been characterized as poly-QM by IR spectrometry. It melts at 400 C and is insoluble in all organic solvents below 250 °C. These results have been explained by the formation of two species, QM and acetyl-QM, in the... 

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