The properties of surfaces are becoming increasingly important in almost all industrial sectors. The surface of many materials is often required to have different properties than those of the material in volume. For example, the material should be malleable, but its surface should be hard. Or a fabric should be strong and dyeable like cotton, but at the same time water-repellent.
With different objectives, surfaces can be treated with plasma processes while maintaining the volume properties of the material:
- Surfaces are cleaned and activated so that, for example, coatings and adhesives adhere better to them.
- Surfaces are coated to provide new functions such as scratch resistance, dirt repellence, corrosion protection or additional optical and electrical functions.
- Surfaces are provided with chemical functions that can react chemically with other substances.
In this way, the surface properties of materials can be improved by means of layers or functionalizations deposited in the plasma.
For example, if the tribological properties such as static and sliding friction of bearings and rollers in production and transport systems are improved, expensive wet and dry lubrication processes can be dispensed with. We were able to demonstrate this impressively in the Nanodyn project.
The wetting properties of a material can also be controlled by specifically adjusting its surface energy. For example, we were able to considerably improve the wearing comfort of textiles by plasma treatment and the easy-to-clean surfaces of cleaning cloths. The adhesion tendency (slip stick) observed with elastomer components can also be reduced by plasma coatings. Furthermore, the corrosion behavior of surfaces can also be influenced by the deposition of nanolayers.
Furthermore, the growth of mammalian cells and microorganisms can be influenced by the targeted coupling of chemical groups to the surfaces by means of plasma processes. Antibacterial surface coatings of materials represent only a small range of possible applications of the coatings in biology or medical technology.
Functional coatings ensure - even with low layer thicknesses of less than 100 nanometers - functions such as:
- Defined wetting
- Scratch resistance
- Adhesion in material composites
- Tribological properties: static friction, sliding friction
- Corrosion behaviour
- Adsorption properties
- compatibility or functionality in contact with biological systems.
At Fraunhofer IGB we master a multitude of tasks by using low-pressure plasma technology, partly in combination with wet chemical processes. In many cases we achieve good results by combining plasma pretreatment with a subsequent chemical treatment.
We achieve the surface properties specified by customers by adapting process chemistry and process parameters to the respective substrate. Inert materials such as polyolefins or perfluoropolymers can also be made accessible by plasma chemistry in an economical and environmentally friendly way.