ICMCTF 2023 Session G4-WeM: Hybrid Systems, Processes and Coatings

Thin film deposition appears to be a suitable process for textile finishing at a time when environmental protection is a global concern. It enables textile functionalization without the wet processing drawbacks, such as hazardous wastewaters. Moreover, thin film technology limits the use of chemicals, water, etc., and do not require a drying system resulting in low energy consumption. Water and oil repellent finishes by PECVD are among the most studied treatments for fabrics. While recently there is a growing interest in metallizing textiles using the magnetron sputtering method.

In this work, we demonstrate the successful use of the hollow cathode (HC) technology to impart water repellent property on polyolefin fabric with silicone precursor. The effects of parameters such as power, pressure and gas mixture on waterrepellencyare evaluated according to international standards such as the resistance to surface wetting. The water repellent finish has a resistance surface wetting of 4.5 and decreases steadily after several wash cycles.

Radio frequency Hollow Cathode based hybrid process integrating both Physical Vapor Deposition and Plasma Enhanced Chemical Vapor Deposition was used for deposition of amorphous carbon directly on glass, without using any interlayer. The films grown at 0.25 – 0.5 % of acetylene in the mixture with argon were subjected to high voltage pulses and the performance was compared with uncoated glass samples to test the protection ability of the films, the ability to prevent the deteriorating effects of corona flashovers/arcs. In contrast to the uncoated glass the well adherent carbon films with thicknesses between 3.5 and 17 µm exhibited an excellent protection of the glass substrate against the flashovers/arc damages in both polarities of the electric field with voltages up to 300 kV.

Bulk coating seems to be an intriguing variant of vacuum coating for small mass parts. Compared to individual part coating, the handling effort is considerably reduced. This applies to indirect and direct labor such as the production and maintenance of adapted fixtures and the charging and de-charging of individual parts. Furthermore, the utilization of processing volume can be maximized, avoiding void space between the parts. This benefit turns into a drawback during plasma etching due to the competitive processes of sputter cleaning and re-deposition on the parts. However, plasma pretreatment of the surfaces is an indispensable step also in bulk vacuum coating. Otherwise, the permanent mechanical impact during agitation will entail delamination defects due to interface imperfections. Identification of appropriate plasma pretreatment regimes is as important as the coating step itself.

In case of granular materials, the aspect of an effective removal of adsorbents before the coating step is a major issue. It becomes more and more challenging with decreasing grain size, hence increasing outer surface area of an ever bigger number of grains, and even more difficult if the grains consist of porous material, where inner surfaces are loaded with adsorbates as well.