Preparation And Properties Study Of Aluminium Matrix Porous Ceramic High Damping Composite

The rapidly development of industry and technology require materials to be structure-function integrative. Failing analysis of rocket and satellite shows that 2/3 of the failures were led by vibration and noise. So materials need to have high strength, high module, low density and good damping properties at the same time. Traditional metal, ceramic and macromolecule can not meet this increasing requirement. Metal matrix composites （MMCs） can improve some special properties of materials such as damping properties due to the microstructure changes made by second phase. The main purpose of this paper is to prepare a new kind of high damping material.In this paper ZL102 aluminium alloy was used as the matrix, fly ash and porous Al₂O₃ particle were used as the second phase, 50vol.% fly ash/ZL102 composite and Al₂O₃/ZL102 were prepared composite through pressure infiltration. Microstructure of composites was observed through optical microscope and SEM. Bending properties of composites were tested on bending test machine. Damping properties of composites were investigated by dynamic mechanical and thermal analyzer （DMTA） and damping-resonation analysis system.Microstructure observation shows that both fly ash and porous Al₂O₃ particles uniformly dispersed in the matrix. Fly ash particle has a closed cell structure, but Al₂O₃ particle has a porous structure.Test of mechanical properties showed that the strength and module of two composites are lower than matrix alloy. The strength and module of composites decrease with the particle size increasing. The specific modules are about the same level with matrix alloy. The fracture of composites shows that the rupture mechanism of fly ash/ZL102 composite is: There is a slide between fly ash particle and matrix alloy, this led to a stress concentration at the interface. At last, crack appeared and composite ruptured. The rupture mechanism of Al₂O₃/ZL102 composite is: The shape of Al₂O₃ particle is irregularly. As a result there is stress concentration at sharp angle of Al₂O₃ particle, then crack occurred and led to a cleavage fracture.Damping test shows that both fly ash/ZL102 composite and Al₂O₃/ZL102 composite have better damping properties than matrix alloy. At room temperature, the damping value of Al₂O₃/ZL102 composite and fly ash/ZL102 composite is about 6-7×10-3 and 4-5×10-3. The damping properties increase with the particle size decreasing. The main damping mechanisms are dislocation damping, interface damping and porosity effect.