Papers by Keyword: Precursor Infiltration and Pyrolysis

Abstract: Sino Fibers Reinforced BN Wave-Transparent Composites (SiNO_f/BN) Were Fabricated through Precursor Infiltration and Pyrolysis (PIP) Method Using Borazine as Precursor. The Effect of Pyrolysis Temperature on the Densification Behavior, Microstructures, Mechanical Properties and Dielectric Properties of the Composites Was Investigated. The Results Suggest that with the Increase of the Pyrolysis Temperature from 800 °C to 1000 °C, the Density, Mechanical Properties and Dielectric Constant of the Composites Are Increased, but the Infiltration Efficiency Varies Little. At the Pyrolysis Temperature of 1000 °C, the Density of SiNO_f/BN Composites is 1.84 g∙cm^-3 and the Flexural Strength and Elastic Modulus Are 148.2 MPa and 26.2 GPa Respectively. The Dielectric Properties, Including Dielectric Constant of 3-4 and Dielectric Loss Angle Tangent of below 7×10^-3, Obtained at Three Different Temperatures Are Excellent for the SiNO_f/BN Composites Applied as Wave-Transparent Materials.

Abstract: The ablation properties of C/C-ZrC-SiC composites prepared by precursor infiltration and pyrolysis processes were studied by the H₂-O₂ ablation method. The results indicate that the C/C composite of 1.28 g•cm^-3 was densified to C/C-ZrC-SiC composite of 1.42 g•cm^-3 after infiltration and pyrolysis once, the density increased 10.94%. The linear ablation rate and mass ablation rate of the C/C-ZrC-SiC composites (ρ=1.42g•cm^-3) were 7.22μm•s^-1and 3.88mg•s^-1, which decreased 79.31% and 65.46% comparing with C/C composite of 1.28 g•cm^-3 respectively. The introduction of ZrC-SiC into the matrix greatly enhanced the anti-oxidative and ablation property of the C/C composite. The ablation mechanisms of the C/C-ZrC-SiC composites were supposed to be the synergistic effects of thermo-chemistry ablation (oxidation and sublimation) and mechanical erosion.