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Microwave PECVD with vapours of tetramethyldisiloxane and oxygen was used to deposit transparent organosilicone coatings on PMMA. The ratio of tetramethyldisiloxane to oxygen within the plasma has a large influence on the chemical and physical properties of the deposited coatings. The oxygen flow rate was varied during deposition so as to deposit a chemically graded coating. Grading offers the ability to change the chemical and mechanical properties of a coating from the substrate to the surface. Coatings with constant oxygen flow rate were compared to those with oxygen varied in an exponential-like increase, a linear increase and a logarithmic-like increase during deposition. Additionally, a linear increase in power level during deposition was also explored. The coatings were characterised via their stress levels, refractive index and adhesion to PMMA. Abrasion and durability performance were also determined, via the steelwool test, salt water boil test and stress to craze test. It was found that the rate of grading significantly influenced the stress and performance of the coating. For enhanced coating performance, in all tests, an exponential-like increase of oxygen was shown to be best. Industrially, these coatings are relevant to the aviation and automotive industries as protective coatings on plastic windows or lenses. [ABSTRACT FROM AUTHOR]

Abstract: In this study, the abrasion resistance of a reflective thin film multilayer system consisting of Chromium Nitride (CrNx) layers deposited on specially prepared coated polymeric substrates is presented. The abrasion resistance is quantified by the Bayer abrasion test, and then correlated with the physical properties of the film. Their resistance to abrasion is identified as being defined partially by the microstructure of the layers within the multilayer system. Relative measures of the abrasion resistance are made by quantifying the surface roughness in the specific case where the substrate is the same (hardness and elastic moduli) and the elemental and phase composition of the coating is the same. Importantly, the optical measurement of the diffuse reflectance is used to assess the relative structure of the coatings prior to the abrasion test. By doing so, a useful, non-destructive technique is presented for characterising the relative abrasion resistance of sputtered thin film coatings. [Copyright &y& Elsevier]