Synthesis of biomorphic ZrC/C ceramics from rattan through zirconium oxychloride infiltration and carbothermal reduction

This work reports the synthesis of biomorphic ZrC/C ceramics derived from rattan through infiltration of a Zr-containing salt and further carbothermal reduction of ZrO2. Discs of dried in natura rattan were first pyrolyzed at 800 °C in nitrogen to form bio-carbon templates. The templates were infiltrated with an aqueous solution of ZrOCl2 that precipitated ZrO2 in situ on the bio-carbon cell walls. After five infiltration/drying cycles a weight gain of 112 wt% was achieved. The salt decomposed and the precipitated amorphous ZrO2 crystallized to tetragonal phase at temperatures between 400 and 600 °C as indicated by an exothermic broad peak centered at 530 °C in the differential thermal analysis (DTA) curve. The infiltrated samples were submitted to heat treatments at temperatures between 1200 and 1600 °C for 1–2 h in argon. Carbothermal reaction took place between 1400 and 1500 °C, where both tetragonal ZrO2 and cubic ZrC were identified by X-ray diffractometry (XRD). Above 1500 °C only ZrC was detected, resulting in porous biomorphic ZrC/C ceramics, where the original anatomic features of the rattan templates were maintained.