S. Safi, R. Yazdani Rad, A. Kazemzade, Y. Safaei Naeini, F. Khorasanizadeh,
Volume 9, Issue 2 (6-2012)
Abstract
C-SiC composites with carbon-based mesocarbon microbeads (MCMB) preforms are new type of highpreformance and high-temperature structural materials for aerospace applications. In this study MCMB-SiC composites with high density (2.41 g.cm-3) and high bending strength (210 MPa,) was prepared by cold isostatic press of mixed mesophase carbon powder derived from mesophase pitch with different amount (0, 2.5, 5%) nano SiC particles. All samples were carbonized under graphite bed until 1000 °C and finally liquid silicon infiltration (LSI). Microstructure observations resultant samples were performed by scanning electron microscopy and transition electron microscopy (SEM & TEM). Density, porosity and bending strength of final samples were also measured and calculated. Results indicates that the density of samples with nano additive increased significantly in compare to the free nano additives samples.
Amin Rezaei Chekani, Malek Naderi, Reza Aliasgarian, Yousef Safaei-Naeini,
Volume 23, Issue 2 (6-2026)
Abstract
A C/C-SiC-HfC composite was fabricated using a three-dimensional orthogonally woven (3DW) preform, and the effect of HfC ultra-high temperature ceramic (UHTC) particles on the microstructure and ablation properties of the composite was evaluated. First, pyrolytic carbon (PyC) was infiltrated into the 3DW preform by the I-CVI method. Then, impregnation of a suspension composed of HfC particles and phenolic resin into the 3DW preform. Next, liquid Si alloy was infiltrated into the C/C-HfC porous structure at 1650 °C to form a C/C composite with a SiC-HfC matrix. HfC particles and the continuous SiC phase among carbon fibers were saturated and during the oxyacetylene test, covered the surface of the C/C-SiC-HfC composite as a dense continuous SiO2-HfO2 layer. This layer acted as a barrier against the diffusion of oxygen into the bulk parts of the C/C-SiC-HfC composite. The results of the oxyacetylene flame test at 2500 °C for 120 s showed that the mass and linear ablation rates of the C/C-SiC composite were 4.8 mg/s and 3.75 µm/s, respectively. After the addition of HfC and the formation of the C/C-SiC-HfC composite, these rates decreased to 1.6 mg/s and 0.98 µm/s, respectively.
