Lightweight vitreous carbon material: approaches to making open-pore cellular structure

Cellular vitreous carbons with the open-pore structure are attractive materials in some aerospace applications, such as the super-lightweight structural materials or sandwich core materials in the thermal protection systems. Cellular vitreous carbon (or VC foam) with the open-pore structure can be synthesized by pyrolysis of cellular precursor structures made from some types of resins, such as epoxy or phenolic resins. Several approaches elaborated at RPMI, Belarus can be applied to create the precursor resin foams. The replication approach ensures perfect open-pore structure with the porosity of >90% and high hydraulic permeability. The sacrificial template approach ensures lower porosity and hydraulic permeability, and higher specific strength. In the approach with the deformable space-holder granules in the sacrificial template, the foam porosity can be controlled in a wider range. The paper compares different methods of making the precursor resin foams and properties of VC structures synthesized by pyrolysis of these precursor foams.