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Gas phase processing of porous, biomorphous TiC-ceramics

Abstract:

Specimens of natural pine wood were converted into biomorphous TiC-ceramics by CVI-R processing (chemical vapor infiltration - reaction). The wood samples were first pyrolysed in inert atmosphere at temperatures of 800°C to yield biocarbon-derived template structures (CB-templates). Subsequently, the CB-templates were infiltrated with titanium-tetrachloride (TiCl4) in excess of hydrogen at temperatures above 1200°C by isothermal CVI processing. Elemental Ti was deposited on the surface of the CB-struts within the pores. During processing the carbon of the CB-template reacted with the deposited Ti to form TiC-ceramics. The infiltration of the Ti-species into the porous carbon template, the micro morphology and phase distribution of the TiC-ceramics were investigated by XRD, SEM/EDX-analysis as well as porosity measurements. The highly porous, biomorphous specimens was homogenous converted into TiC and exhibits of nano-crystalline TiC-phase on the inner surface of the carbon struts. Residual carbon was found in the center of initial carbon struts, especially in late wood areas where the carbon strut thickness was more than 3 μm.