fabrication, microstructural characterization, and ablation behavior of a novel 3d orthogonal woven c/c-sic-zrb2 composite through i-cvi, si, and lsi combined processes

This paper presents the novel fabrication method of a three-dimensional orthogonally woven (3dw) c/c-sic-zrb2 composite and the effects of zrb2 and sic particles on microstructure and the ablation behavior of the c/c–sic–zrb2 composite are studied. c/c–sic–zrb2 composite was prepared by isothermal-chemical vapor infiltration (i-cvi), slurry infiltration (si), and liquid silicon infiltration (lsi) combined process. pyrolytic carbon (pyc) was first infused into the 3dw preform by i-cvi at 1050°c using ch4 as a precursor in order to form a c/c preform with porous media. the next step was graphitization at 2400°c for 1hr. then  zrb2 was introduced into 3dw c/c preform with a void percentage of 48 by impregnating the mixture of zrb2 and phenolic resin, followed by a pyrolysis step at 1050°c. a liquid si alloy was infiltrated, at 1650 °c, into the 3dw c/c composites porous media containing the zrb2 particles to form a sic–zrb2 matrix. an oxyacetylene torch flame was utilized to investigate the ablation behavior. zrb2 particles, along with the sic matrix situated between carbon fiber bundles, form a compact zro2-sio2 layer. this layer acts as a barrier, restricting oxygen infiltration into the composite and reducing the erosion of carbon fibers. the findings were supported by fesem imaging and further confirmed through x-ray diffraction and eds analysis. the addition of zrb2 to the c/c-sic composite resulted in a lower mass and linear ablation rate; 2.20 mg/s and 1.4 µm/s respectively while those for c/c-sic composite were 4.8 mg/s and 6.75 µm/s after ablation under an oxyacetylene flame (2500°c) for 120 s.