Atmospheric-pressure air plasma sources for cleaning and activation of float soda-lime glass: Effects and comparison

The effects of atmospheric-pressure air plasma treatment on the surface properties of common float soda-lime glass were studied using four different plasma sources. The purpose of the studied treatment was to remove contamination and activate the surface with hydrophilic functional groups, without affecting the surface morphology, by balancing the involved mechanisms. The in-depth chemical XPS analysis, based on the achieved hydrophilic effects and ageing recovery evaluated by WCA measurement, revealed a proportional distribution of the various processes involved, which were complemented by AFM measurements. An exposure time of 1 s caused significant modification of the glass surface with all tested plasma sources, while the specific properties of the obtained effects varied due to individual physical plasma parameters. The effects of the treatment with gliding arc, plasma torch, and multi-hollow surface dielectric barrier discharge exhibited some undesirable properties such as non-uniformity, rapid hydrophobic recovery, thermal damage or unbalanced removal of surface material. Only the treatment with diffuse coplanar surface barrier discharge plasma achieved optimal results that met all the investigated parameters and requirements of conditioning the float glass as an interface for bonding of additional materials. Comparing four plasma sources with different physical characteristics provided valuable information about their potential use for applications that involve adding materials to glass surfaces in the form of thin films, coatings, and layers.