Preparation and comparative evolution of mechanical behavior of Fe and Fe2O3 foams and their polymer composites

The open cell foams with reticulated structure are cellular materials which is gaining interest in the recent past not only because of scientific interest but also because of their technological importance. By the virtue of their inherent properties derived out of their unique structure, made them promising and rather indispensable materials for wide range of applications. Some of the examples are structural parts, aerospace components, filters, energy absorbing, insulation, catalysis, heat exchangers and energy absorption. In the present investigation, highly porous reticulated open cell iron oxide (Fe2O3) and iron (Fe) foams are successfully fabricated by polymeric sponge replication process. In order to explore the possibility to enhance the energy absorption capability of this cellular materials, Fe2O3 and Fe foams prepared in this study are encapsulated and infiltrated with epoxy polymers which have exhibited an enhancement of weight by 1.45-1.90 times as compare to bare foams. These composite specimens are being metallic/ceramic skeletons with second phase as epoxy polymer on encapsulation/infiltration are expected to fail under stresses with unique mechanisms. This substantially enhances the energy absorption though extend of weight increase is not significant. The bare and composite foam samples were evaluated for quasistatic compression and dynamic impact behavior under identical conditions. On compression, a significant enhancement in energy absorption of 42 and 90 times for Fe2O3 and a less prominent enhancement of 1.3 and 1.95 times in case Fe foams are observed on encapsulation and infiltration respectively. Under dynamic impact an enhancement in energy absorption of 4 and 11 times in case of Fe2O3 and for Fe foam 6.3 and 20.6 times are observed on encapsulation and infiltration respectively. It is evident that energy absorption property is a strong function of material of fabrication, epoxy phase and stress type and conditions. The current study demonstrates an effective way to enhance the mechanical properties of ceramic (Fe2O3) and metallic (Fe) cellular foams through epoxy polymer encapsulation/infiltration process though infiltration have exhibited significant increase in both cases.