Characterization of C/C Composites Produced Using 3D-preforms by CVD/CVI Method for Biomedical Applications

In this study, carbon/carbon (C/C) composite structures were produced by depositing a pyrolytic carbon matrix around carbon fibers found in a three-dimensional (3D) preform using the Chemical Vapor Infiltration (CVI) method. The preforms used as starting materials were in orthogonal fiber geometry and 3D carbon fiber knitting structure. The CVI process performed in the CVD (Chemical Vapor Deposition) device was carried out at 1250 ℃, under 2 mbar pressure, with a methane gas flow rate of 2.0 lt/min, for a total period of 312 hours gradually applied in an inert atmosphere consisting of argon and nitrogen gases. The produced block piece was processed to obtain small test samples; tensile and three-point bending tests were applied to the pieces, and their densities were measured. Samples were subjected to in-vitro biodegradation tests in 0.9 % isotonic sodium chloride solution by weight at 37 °C for a total of 21 days. The density and apparent porosity of the produced samples were measured to be 1.395 g/cm³ and 13.424%, respectively. The tensile strength and bending strength of the produced C/C composites were determined to be 252.5±6.20 MPa and 236.6±25.7 MPa, respectively. At the end of 21 days, the biodegradation ratio of C/C composites was calculated as 0.0095%.