Processing of biomorphic porous TiO2 ceramics by chemical vapor infiltration and reaction (CVI-R) technique

作者：Ghanem H; Kormann M; Gerhard H; Popovska N^*

来源：Journal of the European Ceramic Society, 2007, 27(12): 3433-3438.

DOI：10.1016/j.jeurceramsoc.2007.02.197

• CVI-R
• TiO2
• spectroscopy
• porosity
• structural applications

Porous biomorphic TiO2 ceramics were manufactured from paper preforms by chemical vapor infiltration and reaction (CVI-R) in a three-steps process. First, the cellulose fibers of the paper were converted into carbon (C-b) by pyrolysis in an inert atmosphere. Then, C-b-ternplate was infiltrated with a precursor system consisting of TiCl4, CH4 and H-2 to produce porous TiC ceramics, which were oxidized in a final step with air at temperatures in the range of 400-1200 degrees C. Depending on the conversion degree, TiC/TiO2 or TiO2 ceramics were obtained. The kinetics of the oxidation process was studied by thermal gravimetric analysis (TGA) and activation energies of 63 and 174 U mol(-1) were estimated for the lower (400-800 degrees C) and higher (950-1200 degrees C) temperature regions, respectively. The TiO2 ceramics were characterized by Raman spectroscopy (anatase/rutile ratio), SEM/EDX (morphology, composition) and nitrogen gas adsorption (pore structure). It was shown, that the anatase/rutile ratio as well as the pore structure of the resulting TiO2 ceramics could be controlled varying the oxidation temperature. The TiO2 samples obtained by oxidation of TiC biomorphic porous ceramics are lightweight but nevertheless have very good mechanical performances. Their bending strength varies between 30 and 40 MPa at a porosity of 65-70%. These structures have many potential applications, e.g. light structured materials, implants because their bio-compatibility, catalyst support or catalyst for photo catalytic applications.

• 出版日期2007