Ionic Liquids as Quenching Media for Heat Treatment of Metals

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In the first project period, we have shown, that aluminium alloys can successfully be quenched in ionic liquids. Quenching in ionic liquids results in a rapid, but also homogeneous cooling process. The quenching rate can be increased by the addition of water, without inducing macroscopic film boiling. Further, we have shown, that ionic liquids evaporate rather than decompose during fast heating. This successful work shall be continued in four combined directions, to proceed regarding mechanisms of ionic liquid quenching, as well as selection and application of ionic liquid quenchants. The former main selection criterion of a high decomposition temperature is no longer valid. Thereby, the range of possibly suitable ionic liquids increases significantly. E.g. halogen free ionic liquids may be suitable with advantages regarding corrosion and work safety. Further, first promising quenching test of steels (annealing temperature above 800°C) have been performed in ionic liquids. This new application shall be investigated in detail. The huge potential for reducing residual stresses and distortion shall be investigated using more complex and distortion sensitive component geometries. Finally, thermogravimetric measurements shall be improved, to determine boiling temperatures of ionic liquids depending on pressure.