Reinforcement and antioxidizing of porous carbon by pulse CVI of SiC

Abstract

In order to reinforce and antioxidize porous carbon, chemical vapour infiltration (CVI) of SiC was investigated using a repetitive cycle of evacuation of vessel and instantaneous source-gas filling. From a source gas of 5% CH3SiCl3-H2, a temperature range of 1273 to 1373 K was considered to be suitable to infiltrate SiC into a deep level, and surface deposition was enhanced at above 1373 K which led to pore blockage. With 3000 pulses, flexural strength was improved from 35 to about 90 MPa. Several specimens were exposed to air at 1573 K for 1070h during which the specimens were cooled to room temperature between four and seven times. SiC felt was also obtained by oxidation of a carbon skelton after pulse CVI.