Electromagnetically Modified Filtration of Liquid Aluminium with a Ceramic Foam Filter

摘要

Conventional Ceramic Foam Filter(CFF)technology has some difficulties in removing fine particulates(e.g.＜ 20 μm)from liquid aluminium.In the present work the filtration behaviour of 30,50 and 80 ppi CFF filters have been studied in the presence of magnetic fields in the range of 0.06-0.2T,produced by induction coils operated at 50 Hz.A feed recipe containing 90 wt.％of the aluminium alloy A356 doped with 10 wt.％A356 composite,containing 15 wt.％SiC particles with a particle size ranging from 13 to 23 μm,was used.When the results obtained for the experiments conducted under the influence of a magnetic field where compared with similar reference gravity filtration experiments profound changes were observed in the distribution of particulates within,over and below the filter.Significant improvements in the wetting behaviour of the liquid metal to the CFF surface were also observed.It is believed that a successful change in filtration mechanisms is obtained as a result of the presence of the Lorentz forces and the metal recirculation produced by the magnetic field.The magnitude of the Lorentz forces,i.e.the magnetic pressure,are in the present work discussed in relation to the filtration results,and quantified based on experimental data and validated 2D axial symmetric Finite Element Modelling(FEM).