Manufacturing of microcellular, biomorphous oxide ceramics from native pine wood

Pine wood was vacuum infiltrated with different low viscous alumina-, titania- and zirconia-sol. Subsequent pyrolysis in inert atmosphere at 800 °C and annealing in air up to 1550 °C resulted in the formation of porous, microcellular α-Al2O3, TiO2 (rutile) and c-ZrO2 (stabilized by 8 mol% Y2O3), respectively. The conversion process retained the microcellular anatomy of the initial pine wood. An anisotropic shrinkage during pyrolysis and annealing was observed for all samples. While after processing the small pores (<1 μm) in the wood cell walls were vanished, the large pore channels—represented the earlywood and latewood tracheidal vessels—remained in the oxide ceramics and yielded an unidirected porous morphology on the micron level.