Evaluation of SiC/SiC minicomposites with yttrium disilicate fiber coating

Hi‐Nicalon‐S/α‐Y2Si2O7/SiC minicomposites were formed by polymer infiltration pyrolysis (PIP) and characterized by TEM, SEM fractography, tensile testing, and fiber push‐in testing. All minicomposites with α‐Y2Si2O7 fiber coatings had strengths significantly higher than the control samples without fiber coatings. Extensive fiber pullout with debonding at the coating‐fiber interface or within the coating itself was observed in minicomposites with Y2Si2O7 fiber coatings, but no debonding was observed in minicomposites without fiber coatings. Debond energies of 4.5 ± 3, 4.6 ± 3 J/m2 and average sliding stresses of 91 ± 40, 94 ± 40 MPa were measured by fiber push‐in tests.