Effect of boron inclusion in SiOC polymer derived matrix on the mechanical and oxidation resistance properties of fiber reinforced composites

Effect of boron inclusion in SiOC polymer derived matrix on the mechanical and oxidation resistance properties of fiber reinforced composites was investigated. SiC/SiBOC ceramic matrix composites were fabricated using Nicalon and Sylramic silicon carbide fibers and polyborosiloxane as the matrix resin. Oxidation behaviour of SiC/SiBOC at 1000 °C was compared with that of C/C and C/SiBOC composites. Flexural strengths of the composites were evaluated before oxidation and after regular intervals of oxidation. The results indicate that the type of silicon carbide reinforcement plays a crucial role in the oxidation behaviour and flexural property of SiC/SiBOC ceramic matrix composites. After six PIP cycles, Nicalon/SiBOC composite showed a maximum flexural strength value of 108 MPa and a corresponding density of ∼2 g/cc. Sylramic/SiBOC composite exhibited a maximum average flexural strength value of 88Mpa after first PIP cycle and a maximum density of ∼2 g/cc after 6th PIP cycle. SiC/SiBOC composites exhibit superior oxidation resistance at 1000 °C, compared to C/C and C/SiBOC composites. From the results, it was concluded that SiC/SiBOC ceramic matrix composites can be used as structural materials under oxidative atmosphere where stress levels are low.