Electromagnetic shielding effectiveness of aluminum alloy-fly ash composites

The cenosphere and precipitator fly ash particulates were used to produce two kinds of aluminum matrix composites with the density of 1.4-1.6 g cm(-3) and 2.2-2.4 g cm-3 separately. The electromagnetic interference shielding effectiveness (EMSE) properties of the composites were measured in the frequency range of 30.0 kHz-1.5 GHz. The results indicated the EMSE properties of the two types of composites were nearly the same. By using the fly ash particles, the shielding effectiveness properties of the matrix aluminum have been improved in the frequency ranges 30.0 kHz-600.0 MHz and the increment varied with increasing frequency. The EMSE properties of 2024Al are in the range -36.1 +/- 0.2 to -46.3 +/- 0.3 dB while the composites are in the range -40.0 +/- 0.8 to -102.5 +/- 0.1 dB in the frequency range 1.0-600.0 MHz. At higher frequency, the EMSE properties of the composites are similar to that of the matrix. The tensile strength of the matrix aluminum has been decreased by addition of the fly ash particulate and the tensile strength of the composites were 110.2 MPa and 180.6 MPa separately. The fractography showed that one composite fractured brittly and the other fractured in a micro-ductile manner. (c) 2006 Elsevier Ltd. All rights reserved.