Browsing by Author "Fröhlich, M."

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    Ecological and functional optimization of the pretreatment process for plasma based coatings of cutting tools
    (2019) Uhlmann, E.; Riemer, H.; An, S.; Fröhlich, M.; Paschke, H.; Petersen, M.
    Increasing demands in machining of high-tech materials and dry machining lead to higher thermal and mechanical loads on cutting tools. In response to these challenges, enhanced coating solutions are applied to increase performance and life of cutting tools. However, during the production process the cemented carbide substrates are contaminated with grinding oils and residues of organic material. For the subsequent physical vapor deposition (PVD) coating process an intensive and high-quality cleaning process is necessary. In this contribution, plasma electrolytic polishing (PEP) is used as a novel alternative to conventional ecologically harmful cleaning baths. Apart from the ecological advantage, the surface of the substrate can be optimized with regard to the coating adhesion. To examine the performance of the different cleaning processes, machining tests were performed at the IWF to evaluate the layer adhesion and tool life of the tools.
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    Examples for application and diagnostics in plasma-powder interaction
    ([London] : IOP, 2003) Kersten, H.; Wiese, R.; Thieme, G.; Fröhlich, M.; Kopitov, A.; Bojic, D.; Scholze, F.; Neumann, H.; Quaas, M.; Wulff, H.; Hippler, R.
    Low-pressure plasmas offer a unique possibility of confinement, control and fine tailoring of particle properties. Hence, dusty plasmas have grown into a vast field and new applications of plasma-processed dust particles are emerging. There is demand for particles with special properties and for particle-seeded composite materials. For example, the stability of luminophore particles could be improved by coating with protective Al2O3 films which are deposited by a PECVD process using a metal-organic precursor gas. Alternatively, the interaction between plasma and injected micro-disperse powder particles can also be used as a diagnostic tool for the study of plasma surface processes. Two examples will be provided: the interaction of micro-sized (SiO2) grains confined in a radiofrequency plasma with an external ion beam as well as the effect of a dc-magnetron discharge on confined particles during deposition have been investigated.