The influence of different gas phase species and the positive ion density on the water vapor barrier performance of SiO x thin films is investigated in this study. A reactor equipped with a remote 2.45 GHz slot antenna plasma source and a 13.56 MHz-biased substrate holder was used to deposit films from gas mixtures of oxygen and HMDSO. Besides determining the WVTR of films, different excited gas phase species were monitored by means of OES and the positive ion density in pure oxygen was measured by LP. The dependencies of the positive ion density and of the actinometric trends of species on the oxygen flow rate as well as on the power input by RF and MW source were investigated. Both gas-phase diagnosis techniques reveal a higher excitation of the gas-phase in dual mode than in pure RF plasma. Production of atomic species seems to be enhanced under such conditions, which however leads to enhanced oxidation of HMDSO and its fragments by atomic oxygen. Hence, at oxygen flow rates above 200 sccm, enough atomic oxygen seems to be obtained so that the film growth mechanism is dominated by homogeneous combustion reactions, overriding the beneficial effect of the substrate self bias. Thus, a complete loss of the water vapor diffusion barrier is observed. Apart from these defective deposits, typical films revealed low WTVR for the entire variation range in RF mode and below 200 sccm of oxygen flow also in dual mode. Here, a decrease of the WVTR with RF power (i.e. DC self bias) and the oxygen flow rate was obtained, while WVTR could be reduced to 0.1 g Á m À2 Á d À1 corresponding to a barrier improvement by a factor of 150 if compared to uncoated substrate polymers.
New technologies enable the manufacturing of asphalt at reduced temperatures. As a result The energy consumption per ton of asphalt and the emissions at the road construction site drop significantly. Whilst conventional asphalt is produced at around 170 ° C, the low - temperature processes of today allow production temperatures of around 100 ° C. Various technologies for this are ready for application by road construction industry. Foam bitumen, waxes and other additives, special bitumen or alternative mixing cycles can be suitable for use, depending on the application. Changing the way of asphalt production in an industry takes several years or even decades. In this paper, we will present low temperature asphalt technologies based on the promising technology of foam bitumen and how they are applied in practice.
To save resources and reduce the energy consumption during asphalt mix production there are three main approaches: addition of reclaimed asphalt (RAP), lower production temperatures, and reduced moisture content in raw materials. Whereas a high moisture content only influences, thus increases the energy consumption and emissions in the plant, RAP addition and lower production temperatures have a direct impact on asphalt mix properties. The main goal of this study is the production of high quality asphalt mix. Experience has proven that high ratios of reclaimed asphalt can be incorporated into hot mix asphalt at equal quality. Furthermore using foam bitumen to produce warm mix allows mixing and compaction at reduced temperatures with comparable properties to hot mix. Combining asphalt recycling and foam bitumen is a step forward to an efficient and sustainable use of resources. The feasibility of producing high quality warm mix asphalt with foam bitumen and various high RAP percentages was demonstrated in field trials. In several asphalt mixing plants mixes were produced, paved and compacted at reduced temperatures. Asphalt production and laying was attended and analyzed. Additionally, for direct comparison construction sites with conventional hot mix were observed. Mechanical mix properties equal to hot mix asphalt were found independent of the RAP content and production temperature.
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