Mechanical properties of ceramic matrix composites with siloxane matrix and liquid phase coated carbon fiber reinforcement

In order to evaluate the benefits of continuous liquid phase coating (CLPC) for carbon fibers, coated fibers as well as uncoated fibers were applied in the preparation of unidirectionally reinforced ceramic matrix composites (CMCs) with polysiloxane based matrix. Fibers coated with precursor based ceramic or carbon coatings were transferred into prepregs by continuous fiber impregnation with liquid polysiloxane and filament winding. The wet prepregs were cut to shape, laminated and then pressed and cured in the mold at 150 °C for 1 h. The cured polymeric matrix composites were calcined and densified by subsequent precursor infiltration/calcination cycles. The flexural strength of the CMCs was measured by 4-point bending tests, the microstructure was determined by optical and scanning electron microscopy. The application of CLPC coated fibers led to a significant improvement in composite strength and young's modulus compared to identical reference samples with uncoated carbon fibers.