VACUUM CARBON TECHNOLOGIES
About carbon/graphene coating on metal and plastic surfaces
Technically, there are two the most popular methods available on the market of applying carbon compounds on the surface of metal or plastic.
The first method is smearing, which you obviously use in your work now. In this case, the material to be applied to the surface is mixed with the adhesive and forms a slurry. The slurry is applied to the surface, compressed between the rotating rolls, and dried.
The other method is carbon compounds sputtering to the surface.
In the sputtering methods, the most popular method is method CVD (Chemical Vapor Deposition – Chemical vapor deposition). The CVD coating is formed as a result of chemical reactions at a temperature (700-1050) °C. Generally, during the CVD process, the surface of a metal or plastic is placed in the vapor of one or several substances that, when reacting and / or decomposing, producing the necessary substance on the substrate surface. Often a gaseous reaction product is also formed, taken out of the chamber with a gas stream.
The method of magnetron sputtering than we do for the application of various industrially significant coatings, such as wear-resistant or protective coatings several nanometers thick, or production of complex, multilayer coatings or electrically conductive coatings. I’d like to let you know, that magnetron sputtering systems allows creating thin layers with properties and structures may be set and/or vary in the required ranges.
Magnetron sputtering is known by high repeatability and stability of deposited coatings both in terms of coating speed and the resulting coatings parameters. This feature of magnetron systems makes it possible to create rather complex multilayer coatings without thickness control systems for the deposited coating. In addition, the resulting coatings have a low internal stress and resistance, which is an important factor when depositing the coating on thin polymer substrates or foils. Due to the high energy efficiency and the high degree of ionization, magnetron sputtering makes it possible to obtain “high dense” layers of matter/carbon on a cold substrate, which is of great importance for substrate materials that do not allow heating. By adjusting the coating mode, it is possible to create not only dense coatings, but also highly porous carbon coatings. The composition of the carbon coating are amorphous carbon, graphene and nano crystals of diamond or fullerene.
Comparing electrical resistance of carbon coatings, created by different methods, it was found that magnetron carbon coating has the smallest value. The electric resistance of carbon coating deposited by the CVD method is more than ten times higher vs magnetron. The resistance of a carbon coating applied by the smearing method is hundred times or more higher than the resistance of a carbon film obtained by magnetron sputtering.
This benefits the magnetron coating of carbon does not ends up there.
A dense magnetron carbon coating protects the metal from chemical corrosion better than any other of the protective coatings known and provides excellent electrical contact with the lowest contact resistance.
High porosity carbon coating can be used for the production of high-quality membranes or electrodes for electrical energy storage devices.
A dense carbon coating is a perfect current collector for accumulators or supercapacitors. A dense carbon coating has proved itself well when sprayed onto aluminum plates, instead of expensive stainless steel plates, in fuel cells.
The combination of a dense carbon coating with a plasma modification of a metal foil and a highly porous carbon coating allows creation of composite materials with high electrical conductivity. Such materials awaited by the aviation and automotive industries. Composite material from light aluminum with strength of high-quality metals is still a dream, but carbon coatings accelerate its implementation.
Carbon is known to have many allotropes, such as graphite, amorphous (actually nanosized graphite crystallites), diamond, carbon nanotube, graphene, fullerene etc., due to its versatile bonding constructions derived from sp, sp2, sp3 hybrid orbitals as well as p–p ℼ orbitals.
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