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Plasma technology is commonly used in many industries, including in the automotive, microelectronics, packaging and medical device industries.
Along with solid, liquid and gas, plasma is a state of matter. State changes occur by either adding or removing energy from a substance. For instance, if enough heat energy is added to water, it becomes steam.
If enough energy is added to a gas, the gas molecules become ionized, carrying a net positive charge. Sufficient ionization affects the electrical properties of the system to the point it becomes a plasma.
A plasma consists of positive ions, negative electrons, neutral molecules, UV light and excited molecules, which can possess a massive amount of internal energy. In a plasma treatment process, any or all of these ingredients may interact with a surface. By selecting the gas mixture, amount of energy, atmospheric pressure and other factors, the effects of a plasma can be adjusted as desired.
Plasma treatment is often conducted in a vacuum chamber. After air is pumped out of the chamber, a gas flows in and an electrical field is applied to yield a plasma. Plasma treatment is typically carried out at relatively low temperatures, allowing for the treatment of heat-sensitive materials.
Plasma treatment is also conducted with what are known as atmospheric 'jet' plasmas. These plasmas function at ambient atmospheric pressure and are ideal to the localised application in an in-line production process, possibly through the use of automation.
Plasma treatment is most often used to clean, enhance the adhesion qualities of surfaces and produce thin coatings.
Cleaning
Plasma cleaning is capable of eliminating oils and grease down to the nanoscale. It can also reduce various risks of contamination much more efficiently than conventional cleaning processes. Plasma cleaning generates a spotless surface, suitable for bonding or additional processing, without producing damaging waste material.
Ultraviolet light produced in the plasma is very efficient at the breaking the organic bonds of common surface contaminants, including those in oils and greases. Energetic oxygen species in the plasma also perform cleaning actions, reacting with contaminants to create primarily water and carbon dioxide.
A plasma cleaning process for easily-oxidised materials like silver will use inert gases like argon or helium. In this cleaning process, the plasma-activated ions blast away organic contaminants, breaking them down so they can be vaporized and removed from the chamber.
Surface Activation
Many polymers are inert and do not bond readily to other materials, like paints and glues. By attaching polar molecular groups to it, plasma surface activation can increase the adherence of a polymer material surface.
Plasma surface activation can make polymers much more receptive to coatings and bonding agents. Oxygen is commonly used in this process; however, many plasma activations can be conducted with ambient air. Once activated, materials remain in the altered state for anywhere from a handful of minutes to many months, based on the type of material.
Coating
A plasma coating process creates a nanoscale polymer layer over the surface of an object. The process requires only a few minutes to produce a coating less than 1/100th the width of a human hair. Attached at the atomic scale, these coatings are typically clear, odourless and otherwise undetectable.
Plasma coatings are currently a hot topic in many scientific fields because they have massive potential in a broad range of applications.
Potential Future Uses
Many are predicting that plasma will be used in new ways in the not-too-distant future.
One potential use is the destruction of toxic waste. Capable of containing enough energy to change the atomic structures of substances, plasma could possibly be used to completely eradiate very harmful toxic substances.
Plasma is already being used as a very precise scalpel for medical operations. Hot plasma could also be used in medicine to cauterize wounds, drill cavities and sanitize.
Ground-breaking particle scientists are already working with plasmas to unravel the secrets of the universe. This research could unlock the secrets of existence, but it could also lead to more practical plasma applications.
Sources and Further Reading
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