For a long time, the production of ceramic coatings has only been possible by means of sintering techniques conducted at more than 1,000 degrees Celsius.
For a long time, the production of ceramic coatings has only been possible by means of sintering techniques conducted at more than 1,000 degrees Celsius. However, a novel spraying method, Powder Aerosol Deposition (PAD), enables their production at normal room temperatures. It is therefore highly attractive for industrial applications. Engineering scientists from the University of Bayreuth under the direction of Prof. Dr.-Ing. Ralf Moos are working in the frontline of ongoing development of this technology. In the journal of "Advanced Materials", they present its advantages and show how the functional properties of ceramic films can be optimized with regard to high-tech applications.
With PAD, dense ceramic films can be applied to very different types of materials, such as steel, glass, silicon, or even plastic. To achieve this, a dry ceramic powder is first converted into an aerosol, i.e. a mixture of gas and solid particles, with the aid of a carrier gas. The aerosol is then transported into a vacuum chamber, and accelerated to several 100 meters per second through a nozzle and directed onto the material to be coated. On impact, the tiny ceramic particles fracture. The resulting fragments, only a few nanometers in size, feature fresh, active surfaces. They form tightly adhering, dense coatings with a thickness of between 1 and 100 micrometers.
"Thanks to their dense microstructure, the coatings already exhibit excellent mechanical properties even directly after the deposition. They are extraordinarily hard and have good chemical resistance," explains Dr.-Ing. Jörg Exner, first author of the study, who was a driving force in the research work on PAD at the University.
Read more at University of Bayreuth
Image: The Powder Aerosol Deposition (PAD). CREDIT: University of Bayreuth
