Effect of pyrolysis temperature on the microstructure and thermal conductivity of polymer-derived monolithic and porous SiC ceramics

摘要

The present work investigates the influence of pyrolysis temperature on the microstructure and thermal conductivity (lambda) of polymer-derived SiC ceramics. For the study, both monolithic thin ceramic disks and highly porous reticulated foams were considered. The lambda of the polymer-derived SiC disks were measured, in the temperature range 100 degrees C-1000 degrees C, to amount between 0.5 W.m(-1). K-1 and 47 W.m(-1). K-1 ms (porosity 79.5 %-99.0 %), ranges between 0.03 W.m(-1). K-1 and 0.19 W.m(-1). K-1. The thermal transport in polymer-derived SiC ceramics was observed to be more significantly governed by the nanocrystalline to crystalline transition which occurs at pyrolysis temperatures above 1200 degrees C as compared to mesopore formations or the nature and amount of free carbon.