1 research outputs found
Evaluating Use of Boron- and Hafnium-Modified Polysilazanes for Ceramic Matrix Minicomposites
In this study, the
potential of polymer-derived ceramic matrix
composites (CMCs) is demonstrated by the addition of thin ceramic
coatings on carbon fiber (CF) bundles. Boron- and hafnium-modified
polysilazane liquid precursors were synthesized and used to infiltrate
the fiber bundles of CF to fabricate lab-scale Si(B)CN/CF and Si(Hf)CN/CF
CMC minicomposites, respectively by crosslinking and then pyrolysis
at 800 °C. The crosslinked precursor to ceramic yield was observed
to be as high as 90% when the procedure was carried out in inert environment.
The Si(B)CN/CF contained Si–N and B–N bonds, while Si–N
and Hf–O–Si bonds were observed for the Si(Hf)CN/CF
sample with uniform and dense surfaces. Room-temperature tensile tests
showed that the Si(Hf)CN/CF sample could reach a tensile strength
of ∼790 MPa and an elastic modulus of 66.88 GPa among the composites.
An oxidation study of the Si(Hf)CN/CF minicomposites showed higher
stability compared to SiCN/CF and Si(B)CN/CF minicomposites up to
1500 °C