Mechanical and thermal properties of low temperature sintered silicon carbide using a preceramic polymer as binder
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Silicon carbide is used for a variety of applications, however, sintering still remains a challenge due to the high temperature and pressure required as well as the need for sintering aids. The use of preceramic polymers as binder is a promising technique for pressureless low-temperature sintering of SiC without sintering aids. However, the mechanical and thermophysical properties as well as the microstructure of bodies sintered through this technique has not been extensively documented. One of the main polymers which has gained attention in the past few years as a SiC preceramic is allylhydridopolycarbosilane (AHPCS). Here, using AHPCS as binder, silicon carbide pellets were sintered at temperatures as low as 930 °C, and the microstructural, mechanical, and thermophysical property characterization is presented. Compared to conventionally sintered SiC, the material shows similar fracture toughness, lower hardness, strength, and thermal conductivity. The observed properties are explained as a result of residual porosity combined with amorphous SiC at the grain boundaries.
KeywordsFracture Toughness Firing Temperature Preceramic Polymer Silicon Oxycarbide Inverse Diffusivity
The authors gratefully acknowledge Dr. John Mecholsky, Dr. Anthony Brennan, Dr. Ronald Baney, and Dr. Gerald Bourne for allowing us the use of equipment necessary to carry out most of the measurements. We also thank Dr. Chunghao Shih for his help on the experimental part of this work. Finally, we recognize the Major Analytical Instrumentation Center at the University of Florida for providing access to the SEM and the Nano Research Facility at the University of Florida for providing access to the microRaman spectrometer. This material is based upon the work supported under a Department of Energy Nuclear Energy University Programs Graduate Fellowship.
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