Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5440932 | Journal of the European Ceramic Society | 2017 | 10 Pages |
Abstract
A two-step process has been developed for silicon carbide (SiC) coated polyurethane mimetic SiC preform containing silicon nitride (Si3N4) whiskers. SiC/Si3N4 preforms were prepared by pyrolysis/siliconization treatment at 1600 °C, of powder compacts containing rigid polyurethane, novolac and Si, forming a porous body with in situ grown Si3N4 whiskers. The properties were controlled by varying Si/C mole ratios such as 1-2.5. After densification using a chemical vapour infiltration, the resulting SiC/Si3N4/SiC composites showed excellent oxidation resistance, thermal conductivity of 4.32-6.62 Wmâ1 Kâ1, ablation rate of 2.38 Ã 10â3 â 3.24 Ã 10â3 g cmâ2 s and a flexural strength 43.12-55.33 MPa for a final density of 1.39-1.62 gcmâ3. The presence of a Si3N4 phase reduced the thermal expansion mismatch resulting in relatively small cracks and well-bonded layers even after ablation testing. This innovative two-step processing can provide opportunities for expanded design for using SiC/Si3N4/SiC composites being lightweight, inexpensive, homogeneous and isotropic for various high temperature applications.
Related Topics
Physical Sciences and Engineering
Materials Science
Ceramics and Composites
Authors
Shameel Farhan, Rumin Wang, Kezhi Li,