Preparation and properties of biomorphic potassium-based geopolymer (KGP)-biocarbon (C_B) composite

Anisotropic, biomorphic (wood-derived) potassium-based geopolymer (KGP) - biocarbon (C_B) composites with net shape were manufactured by infiltrating KGP slurry into monolithic porous biocarbon (C_B) structures (~77 vol% porosity) derived from pyrolyzing beech wood. About 70% of the pores in the three-dimensional (3D) C_B structures were infiltrated by the KGP slurry. Compared to pure KGP, the energy absorption per unit volume in compression loading of the KGP-C_B composites was increased by ten-fold. After heat treatment at 1000 °C for 1 h in N₂, the compressive strength of the KGP-C_B composites increased from ~7–24 MPa, accompanied by the formation of crystalline leucite (K₂O·Al₂O₃·4SiO₂) phase in the KGP. The KGP-C_B composite also exhibited three orders higher electrical conductivity than pure KGP. The effect of temperature on the formation of crystalline phases in KGP and KGP-C_B composites was investigated. FTIR, TGA and SEM analyses were used to investigate the changes in microstructures and phase formation during thermal treatment.