An original way to investigate the siliconizing of carbon materials

The reaction of liquid silicon with glassy carbon and polycrystalline graphite was investigated according to two siliconizing processes. In the first process, the reactants are progressively heated from room temperature up to 1600 °C. In the second one, the liquid silicon is poured onto the carbon sample once the reactants have reached the required temperature, in order to consider short reaction times. Thus, an original equipment consisting of a graphite reactor, has been specially designed for this purpose. The nature and the growth rate of the resulting silicon carbide has been studied using scanning electron microscopy. The results showed the formation of a thin continuous layer of SiC crystallites at the liquid silicon/carbon interface. The thickness of the layer shortly becomes independent of reaction time (about 10 μm on glassy carbon and 15 μm on polycrystalline graphite after 30 min reaction time) while some isolated SiC particles appear in the solidified silicon phase, as well as a regular and unusual time dependent SiC layer at the silicon melt/atmosphere interface.