Planar flow casting is a rapid solidification process used to manufacture thin, metallic ribbons, and foil well established at the Department of Physics. In this work published in Journal of Materials Research and Technology, researchers focused on a new method to control the ribbon thickness over a length of 50 m by reducing the wheel speed at the start of the cast. This method was not already reported and was named using his inventor’s name as Reimann Brake Ramp. Moreover, the development of an automatized melt spinner permitted monitoring and controlling the process parameters, elucidating the ribbon’s gluing phenomenon during the starting phase.

Original article: "Reimann Brake Ramp for planar flow casting processes and analysis of ribbon gluing", Laurent Marot, Silvester Jakob, Marco Martina, Peter Reimann^†, Heinz Breitenstein, Michael Steinacher, Ernst Meyer, Journal of Materials Research and Technology, https://doi.org/10.1016/j.jmrt.2021.11.129

The metallically shining appearance is typical for the metallic glass foils. They look like aluminium foil as we know them from the household. However, tin-foils are produced under big energy involved by gradual roll down of the aluminium blocks. In contrast, the metallic glasses are manufactures by pouring the melt directly in one step onto the spinning wheel adjusting the desired thickness. This procedure is called Melt Spinning. 

Investigation on the structure of metallic glasses: 

Chain-like structure elements in Ni40Ta60 metallic glasses observed by scanning tunneling microscopy, R. Pawlak, L. Marot, A. Sadeghi, S. Kawai, Th. Glatzel, P. Reimann, S. Goedecker, H.-J. Güntherodt, E. Meyer, Nature Scientific reports, 5, (2015), 13143

The liquid alloy is squeezed through a small slit at the nozzle bottom with light overload pressure onto the surface of a rotating copper wheel. The melt solidifies instantly. The typical cooling rate is 1 million degrees per second. The resulting metallic glass is amorphous and only about 50 micrometers thick. This specific foil production process directly from the melt without rolling is very efficient and saves a lot of energy. Applications as core material in power supplies and distribution transformers are typical. Energy-savings and improvements in the economy are the advantages. Further applications to use them as active brazing foils to join engineering ceramics are increasing.

For more than 20 years the Department of Physics, in close collaboration with Endress+Hauser Maulburg (Germany) and Flowtec (Switzerland), has developed a specific metallic foil for industrial applications for sensor in pressure measurements (details above).

Metallic foils are used to welled ceramic parts from a pressure measurements system from Endress+Hauser.

In our facility, we deposit by magnetron sputtering metal, oxide films for several applications. Example are TiAlN for mechanical properties, rhodium for watch industry. Rare-earth oxide surfaces were recently reported to possess intrinsic hydrophobicity in Külah, E., Marot, L., Steiner, R., Romanyuk, A., Jung, T. A., Wäckerlin, A., & Meyer, E. (2017). Surface chemistry of rare-earth oxide surfaces at ambient conditions: reactions with water and hydrocarbons. Scientific Reports, 7, 43369.

Rare earth oxides (red/orange) react with gaseous organic compounds from the ambient air to form carbonates and hydroxides (grey/white). Through this reaction, the surface develops water-repelling properties.

M-Glass: Innovative coatings for sun protection glasses based on the theory of optimized spectral transmittance.

These coatings reduce the solar-thermal load of building's interior by one third in comparison to current sun protection glasses on the market. Apart of the comfort improvement for occupants, the energy necessary for cooling of buildings is reduced. Therefore these new coatings can contribute to the measures needed to reduce global climatic changes.

For more information, please click here. 

Within several different projects, in close collaboration with Glas Trösch and others, the Department of Physics contributed to develop innovative coatings for the market.