Fabrication and microstructure of 3D Cf /ZrC-SiC composites: through RMI method with ZrO2 powders as pore-making agent

3D Cf/ZrC-SiC composites were prepared by a combination process of slurry infiltration and reactive melt infiltration. ZrO2 powders and ZrSi2 alloy, both of which reacted with amorphous carbon, were used as pore-making agent and infiltrator, respectively. After carbothermal reduction at 1650 °C, X-ray diffraction analysis revealed that ZrO2 powders were completely converted into ZrC by reacting with amorphous carbon, and an in-situ formed submicron porous configuration was observed at the areas containing ZrO2. Results showed that the matrix in composites mainly consisted of SiC, ZrC and a small quantity of residual metal. SEM and TEM images revealed the formation of ZrC or SiC intergranular particles in the matrix and the characteristic around the residual resin carbon. The composites had a bending strength of 94.89±16.7 MPa, fracture toughness of 11.0±0.98 MPa m1/2, bulk density of 3.36±0.01 g/cm3, and open porosity of 4.64±0.40%. The formation mechanisms of ZrC-SiC dual matrix and intrabundles׳ structure were discussed in the article.