Internal oxidation and metal dusting of Fe–Si alloys

Iron and Fe–Si alloys (1, 2, 3 and 5 wt.% Si) were reacted at 680 °C with a gas mixture of 68% CO, 26% H2 and 6% H2O (aC = 2.9, pO2pO2 = 2 × 10−23 atm). Alloy reaction products consisted of internally precipitated SiO2, an external scale of Fe3C + SiO2 and surface coke deposits containing cementite and silica particles. Coking and metal dusting rates both increased with alloy silicon level. This is proposed to be related to an increase in graphite nucleation sites at Fe3C/SiO2 phase boundaries, and the volume expansion accompanying graphite precipitation.