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Surface Modifications for advanced applications

Final Report Summary - SUMA2-NETWORK (Surface Modifications for advanced applications)

The multidisciplinary SUMA2 Network collaborates in the field of materials surface modification for advanced applications. It is composed of three Universities and one research center in Europe: Linköping University (SWE), University of Lorraine (FRA), Saarland University and Fraunhofer Institut for Material and Beam technology (GER); and five Universities in Latin American: Universidad Nacional de Río Cuarto, Universidad Nacional del Comahue, Universidad Tecnológica Nacional (ARG), Pontificia Universidad Católica de Chile (CHI), and Universidade de Caxias do Sul (BRA). The purpose of the network is to combine different areas of expertise in physics, chemistry, materials science, materials engineering, mechanical engineering and electronic engineering towards the development of optimized surfaces for different applications, such as: gas sensors, transparent p-n junctions, organic solar cells, electrochemical electrodes and wear resistant and anticorrosive surfaces.
Different processing technologies like plasma assisted thermochemical diffusion, physical and chemical vapor deposition, laser-induced forward transfer (LIFT) and direct laser patterning (DLIP), were combined for modifying the surfaces of different types of materials.
The surface of steel was treated by plasma assisted thermochemical diffusion, i. e. nitration and nitrocarburizing to improve the tribological behaviour of corrosion resistant surfaces. DLC-layers were deposited on the treated stainless steel samples. The tribological behaviour of a-C:H thin films on steels was improved, having a strong relation to the previous thermochemical diffusion treatment. This topic has a high technological impact due to the ultra-low friction coefficient of a-C:H and related materials deposited onto steels, leading to an increase in the energy efficiency of mechanical devices such as engines, transmissions and gear boxes of automobiles. Finally, the characterization of the fabricated nitrided stainless steel surfaces with different proportions of paramagnetic and ferromagnetic phases helped in understanding the structural effects of these phases, as well as the nitrogen diffusion mechanism.
Using the LIFT techniques on metals and conducting polymers, nanostructured electrochemically active electrodes were produced. Moreover, LIFT was used to produce gas sensors based on functionalized carbon nanotubes and polyaniline films. This optimized technique provides a fast and accurate tool to produce such electrodes and sensors with a strong up scaling possibility. Moreover, this technique provides us with the possibility to create arrays of Au – MWCNT sensors that will be of enormous importance when developing more selective gas sensors. So far we have evaluated the response of CNTs sensors towards H2 and CO; and PANI sensors towards different VOCs. The effect of ambient humidity on the response was elucidated.
Further material synthesis included p-type transparent conductors as well as p-n junctions, opening new possibilities in transparent microelectronics’ field. The deposition of organic small-molecule layers by vapour deposition through close-space sublimation was successfully achieved. An optimum light trapping structures for organic solar cells were calculated based on finite element simulations of sunlight absorption in organic layer stacks. After that, DLIP was used to structure the surface of the cell increasing the efficiency of it after a thorough optimization process.
80 exchanges were completed giving place to a strong interaction among the project partners. Besides the project meetings, three further workshops were realized in Latin America: Santiago de Chile (2014), Río Cuarto (2015) and Montevideo (2016). European and Latin American researchers participated on them designing new collaboration strategies for the future. Through the activities of the project, more than 38 peer-reviewed publications and 40 contributions in conferences were achieved.
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Contact: Dr.-Ing. Flavio Soldera, Universität des Saarlandes, Campus D3.3 66123 Saarbrücken,