Mg-matrix syntactic foam filled with alumina hollow spheres coated by MgO synthesized with solution coating-sintering

Abstract

For a long time, the extremely high chemical activity of magnesium melt with ceramics at high temperatures makes it challenging to synthesize Mg-matrix syntactic foams (MgSFs) by casting. In this work, for the first time, high porosity of AZ31B magnesium alloy matrix syntactic foams containing Al2O3 hollow spheres (Al2O3-HS) were successfully synthesized by gravity infiltration casting. The Al2O3-HS were coated with MgO using MgCl2 solution after high-temperature calcination to prevent the interfacial reaction. The results show that the concentration of the MgCl2 solution strongly influences the porosity of the syntactic foams because it determines the coverage of Al2O3-HS with the MgO coating and the survival of particles. The maximum porosity of the syntactic foam was 41.64 vol%, and the corresponding density was 1.17 g/cm3. At the MgCl2 solution coating concentration of 0.15 g/ml, the plateau stress of the syntactic foam reaches the maximum value of 55.96 MPa, the energy absorption capacity was 39.27 MJ/m3, and the maximum energy absorption was 26.06 kJ/kg. These properties are comparable to some MgSFs prepared by other methods in recent years.

Keywords

• Mg-matrix syntactic foam
• Gravity infiltration casting
• MgCl2 solution coating concentration
• Compressive property
• Energy absorption performance