Effect of addition of B4C particles to SiC-carbonmesophase composites

摘要

Binderless polyaromatic mesophase (BPAM) can be used to prepare high density graphites of excellent mechanicalproperties. For certain applications, this materials, however, are claimed to have low mechanical strength and lowdegree of oxidation resistance at high temperature. The manufacture of composites of SiC-BPAM is being studied asa way of improving the fragility and oxidation resistance of carbon materials. Α-SiC particles are mixed with BPAM(10-30 % SiC), conformed and heat-treated under inert atmosphere (1000 and 1450°C). Mechanical tests of thesesamples indicate that reinforcement of the compacts is not achieved and mechanical properties even get worse whenthe amount of SiC is high. The main reason was the low physical bonding between SiC and carbon particles.The additions of small amount of boron carbide particles to the row mixture seems to resolve the latter problem. Themechanical properties analysis shows that the samples with B4C have a higher flexural strength. Additionally, theoxidation resistance of all the samples improve with the addition of the B4C particles. Thermo mechanical analysishas revealed to be a more sensitive technique than thermogravimetrical analysis to detect oxidation of the samples.