Ionic Liquids for immersion quenching of aluminium alloys
It’s common knowledge, that baths of molten salts and molten metals provide a quenching without any Leidenfrost-Effect. Nevertheless, they need to be operated at elevated bath temperatures combined with a considerable effort for cleaning the quenched components. In this work Ionic Liquids ,a new class of liquid quenching media, are investigated, showing nearly no Leidenfrost-Effect and can be used in baths at room temperature. These quenching media are salts with melting temperatures below 100 °C (often below room temperature). Therefore, these Ionic Liquids should be able to provide a fast and homogeneous cooling.
Aluminium and steel cylinders have been quenched in baths of different Ionic liquids with varying compositions and bath temperatures. The time-temperature curves have been recorded and the heat transfer coefficients were determined and compared to quenching in water. Some selected quenching experiments were recorded with a high speed video camera. It was shown, that the cooling power of Ionic Liquids could be significantly increased by water addition without any Leidenfrost-Effect. The results indicate a huge potential to homogenise immersion quenching.
Additional investigations on distortion of complex aluminium profiles quenched in ionic liquid and water have been carried out. The distortion measurements were compared to quenching simulations. Short time and long time thermal stability, costs, work safety and component cleaning of the new quenching media were also considered.