A method for magnetic conversion from paramagnetic to ferromagnetic of microporous metal materials, ferromagnetic microporous metal materia obtainable thereby and their uses

Most of the heating systems for fluids are based on electrical resistances that are placed inside the fluid to heat it via Joule effect. Also, there is a possibility to directly heat metal pipes via Joule heating. This is used in heaters that can be applied to heat tap or shower water.However, the hating of the fluids in both cases in not efficient due to a poor heat transfer from the Joule heated conductor to the fluid. To increase the heating efficiency and the heat transfer capability porous materials can be used.The present invention relates to methods for magnetic conversion of microporous metal materials from paramagnetic to ferromagnetic. In particular, the present invention relates to a conversion method for changin (converting) magnetic behavior of microporous austenitic stainless-steel materials from aramagnetic to ferromagnetic.The invention also relates to the ferromagnetic microporous stainless-steel materials obtainable thereby as well as to their uses, particularly in applications where an efficient heat exchnger for fluids is required.