Effect of PyC interface phase on the cyclic ablation resistance and flexural properties of two-dimensional Cf/HfC composites.

• C f /HfC and C f @PyC/HfC composites were prepared at low temperature by precursor infiltration and pyrolysis and chemical vapor deposition method. • The results of thermal cyclic ablation and three-point bending tests show that after three time ablation cycles, the flexural strength of C f /HfC samples reduced by 63%; the flexural strength of C f @PyC/HfC samples only reduced by 36%. • The differences of cyclic ablation behaviour and flexural strength of C f /HfC and C f @PyC/HfC are attributed to the crucial function of PyC interface phase including protection of fiber and weakening of fiber/matrix interface. Composites based on hafnium carbide and reinforced with continuous naked carbon fiber with and without PyC interface were prepared at low temperature by precursor infiltration and pyrolysis and chemical vapor deposition method. The microstructure, mechanical property, cyclic ablation and fiber bundle push-in tests of the composites were investigated. The results show that after three times ablation cycles, the bending strength of samples without PyC interface decreased by 63.6 %; the bending strength of samples with PyC interface only decreased by 37.8 %. The force displacement curve of the samples with PyC interface presented a well pseudoplastic deformation state. The mechanical behavior difference of two kinds of composites was due to crucial function of PyC interface phase including protection of fiber and weakening of fiber/matrix interface. [ABSTRACT FROM AUTHOR]