Sintering of silicon carbideI. Effect of carbon

The role of carbon in activating the process of SiC sintering is not fully understood. In the present work we examined the weight and microstructure changes of samples sintered with different additions of carbon (up to 16 wt.%). The measurements were carried out in the temperature range 1000–2200 °C. In comparative studies we examined the variations of oxygen content with the sintering temperature. The obtained results indicate that carbon blocks the mass transport processes which are ineffective in densification and enables maintaining proper dispersion of SiC grains up to the temperatures where, due to boron, pore elimination begins. On the basis of microstructural observations of SiC sintered with different amounts of carbon it has been stated also that this additive prevents grain growth of SiC on sintering.