by Wes Noble
What is Plasma?
Plasmas are the fourth state of matter and believed to be the most common state of matter in the universe. In simple terms, plasma is an ionized gas into which enough energy is provided to free electrons from atoms or molecules and coexist in both the negative and positive state (Kross, Brian. “What Is Plasma?” Jlab.org. Jefferson Lab, n.d. Web.).
Solid + Enough Energy = Liquid
Liquid + Enough Energy = Gas
Gas + Enough Energy = Plasma
What is Plasma Treatment?
Plasma Treatment is a form of surface modification. It is used in the pretreatment of material surfaces prior to gluing, bonding, painting, dispensing, or coating and can be used on virtually any material surface including those of textiles, metals, plastics, glass, etc.
Plasma is generated by combining a gas with an increased amount of energy where the gas becomes electronically charged with freely moving electrons in both the negative and positive state. This cocktail of neutral gas atoms, positive ions, UV light along with other excited gas molecules and atoms is packed with loads of internal energy. Plasma treatment is initiated when this energy comes into contact with the surface of a substrate.
Plasma treatment modifies the surface of a material by increasing its surface energy. It’s like sanding a surface with a microscopic fine abrasion. The treatment smoothes the surface but generates an increased amount of surface area as a result of the surface modification. This allows for better wettability and flow to occur within the treated area. The outcome produces better coverage and allows adhesion to take place on materials where never before possible.
There are two common forms of plasma treatment Low Pressure Plasma (Vacuum Plasma) and Atmospheric Plasma that are used for surface modifications of substrates. Vacuum Plasma is created using a vacuum pump in which most of the air is removed from a sealed chamber. With enough air removed, the chamber low-pressure reaches adequate levels for ionizing the remaining air or gases with a strong electrical field producing plasma. All surfaces of a material are treated at the same time using Vacuum Plasma. Atmospheric Plasma on the other hand requires no closed chamber, it is produced by electrically energizing air or gases as they pass through a nozzle at surrounding atmosphere or normal pressure using a pulsed electric arc generated by high voltage discharge.
Why use Plasma Treatment?
Plasma treatment can be used on any surface. It strengthens the bonds between surfaces, it improves the ability for coatings to adhere to surfaces, and allows for adhesion to occur on surfaces were previously impossible. When surfaces are plasma treated prior to coating, painting, or bonding; the risk of adhesion failure is substantially reduced. It removes contaminants e.g. oils, glues, silicones, oxide, and other organic and inorganic compounds without damaging the substrate. Surfaces also stand to benefit from improved wettabiliy, it raises the surface energy and lowers surface tension to improve flow and wetting.
What are the advantages of using Atmospheric Plasma?
Atmospheric Plasma treatment has many advantages over the use of Vacuum Plasma. Atmospheric Plasma does not require a confined vacuum chamber. Because of this, it allows for plasma treatment directly in-line with a manufacturing assembly process. Objects extremely long in nature can be treated with very short processing times. Treatment is possible directly before the gluing, bonding or coating of a process. Additionally, it allows for selective plasma treatment removing contaminants and permits adhesion in problematic regions of substrates.
For more information visit our Plasma Treatment Systems page