In its physical definition, plasma is an ionized gas. It means part of its atoms or molecules have a non neutral electrical charge, either after having lost one or several electrons (which become free electrons) or after having absorbed an electron.
As a consequence, plasma can transport electrical charges, which means it can conduct electricity, as opposed to a normal gas that is an electrical insulator.
A plasma holds numerous species : free electrons, positive or negative ions, radicals, metastables. All these species and their associated electromagnetic rays can be used in the technological use of plasma.
A popular method for creating a plasma is to apply a voltage between two conductive electrodes that are separated by a gas.
Atmospheric plasma is a key component for modern cars manufacturing that involves polymers and composite materials. A good adhesion or a good wettability are important criteria for ensuring a production with a good quality. Plasma is an excellent tool for surface treatment in the automotive industry.
Aerospace industry is always looking for new materials: polymers, ceramics, metals, high performance fibers, with light weight and high resistance.
These materials need a good and appropriate surface treatment. Atmospheric pressure plasma surface treatment offers a good option for preparing these materials, as compared to conventional processes that use chemicals.
Polymer surfaces have limited or no affinity with glues or inks. Poor adhesion means poor quality. Adhesion strength is definitively an important constraint in modern manufacturing.
Plasma treatment makes the strongest bond for industry requirements. Plasmas increase tensile strength up to 10 times, and more.
Atmospheric Pressure Plasma processes increase surface energy of materials in two steps. Contaminants are first removed and then, the plasma reacts with the surface, Glue, paint or ink will spread over surfaces easily.
Surfaces are always contaminated by organic layers or native oxides. This is often a consequence of storage or effects of previous processing steps. These contaminants need to be removed for functionality reasons or just to restore surface preparation before printing or gluing. Thin oil films are cleaned in a few seconds with an oxidizing plasma.