Densification of MCMB–SiC composites via two-step hot pressing

Abstract Mesocarbon microbead–SiC (MCMB–SiC) composites with 30 wt% MCMBs were densified using a two-step hot pressing method. Based on the pyrolysis of the initial MCMB powders, the effects of the pressing schedule on densification were investigated and the optimal first-step pressing temperature was determined. To reveal the influence of temperature on their microstructures, the raw MCMB powders were heat-treated at different temperatures in the range 400–1400 °C. The morphologies and degrees of carbonisation at different temperatures were additionally studied. The results showed that densification was mainly affected by the micro-gaps in the lamellar structure formed during the pyrolysis of the MCMBs. When the samples were first hot-pressed at a lower temperature and then at a higher temperature, the densification pressure required was effectively decreased. Furthermore, when the samples were first pressed at an appropriate temperature, the relative density of the composites was improved to a rather high value of 98.6%. The two-step hot pressing method was effective in fabricating dense C–SiC composites with high C content.