Some aspects of graphitization induced by iron and ferro-silicon additions

The effects of the introduction of iron or ferro-silicon particles on the graphitization of carbon mixes at relatively low temperatures are described. It is shown (i) that both iron and ferro-silicon materially accelerate the rate of graphitization and that ferrosilicon is more effective than iron in this respect (ii) that by the inclusion in carbon mixes of about 20% wt. of iron or ferro-silicon leads to extensive graphitization at temperatures as low as 1400°C, (iii) that the most effective silicon content of the ferro-silicon is about 25% and the most effective particle size is in the range 50–75 μ. The mechanism of the acceleration of graphitization has been studied. It is concluded that the graphite nucleates around and within the metal particles and that it is the rapid transport of carbon atoms within the liquid metal which is responsible for the ease of graphitization observed. The mechanism by which the metal is continually dispersed throughout the carbon matrix during graphitization has also been elucidated.