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A new method for transforming wood structures into ceramic by carbothermal reduction of silica and carbonized wood has been developed. Application of this technique allows the preservation of wood microstructures in the ceramic state and the conversion of wood components without constraints in component size. The chosen infiltration technique of silica sol incorporation into carbonized wood structures is examined in terms of sol and wood type, carbonization conditions of the wood, and thickness of the infiltrated carbon body. Ceramization conditions were optimized, and the reaction mechanism is discussed.

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The use of wood as a structure-giving material may be the key to producing temperature-resistant ceramics featuring high and directed porosity combined with necessary strength. The objective of this study was to develop a simple process to convert the evolutionarily optimized material wood into highly porous ceramics. Beech and pine, known to be relatively permeable, were pyrolyzed in a nitrogen atmosphere. The carbon-templates formed were infiltrated with various kinds of silica sol (SiO 2 ). The resulting SiO 2 /C composite was transformed into a SiC-ceramic (silicon carbide) via carbothermal reduction. Through the described process the macroscopic pore-structure of wood was transformed exactly into SiC. The SiC-ceramic produced proved to be thermo-resistant. It remained stable in oxygen atmosphere at 1200°C, after a SiO 2 coating around the SiC had been formed. This study focused on the alteration of the cell wall microstructure during the conversion of wood into SiC. Furthermore, the optimization of the individual process steps, pyrolysis, infiltration and ceramization along the most efficient route was pursued.