Improving the oxidation resistance of carbon fibers via B4C coating by modified boron oxide chemical vapor deposition

Carbon fiber is one of the engineering materials frequently used in high-temperature applications despite its very poor oxidation resistance. To enhance the oxidation resistance of C fibers and improve the service temperature, boron carbide coatings were prepared by the modified reactive boron oxide chemical vapor deposition (BOCVD) method. For the coating process, a tube furnace system was utilized. Experiments were performed at 1100–1400 °C for up to 6 h under a flowing Ar atmosphere. Coatings were analyzed by SEM, Raman, XRD, and XPS analysis. B4C coatings were found to be in nodular form around 30–50 nm. Oxidation tests performed in flowing air up to 1500 °C by DTA-TG analysis and oxidation mechanisms were explained in details. We revealed that the base oxidation resistance increased up to 180 °C with no net mass gain or loss.