1. Silicon additions decrease the parabolic oxidation rate, amount of separated Cu-rich liquid and grain boundary penetration. 2. Increasing silicon content causes an increase in the interface roughness and internal oxidation but did not cause significant occlusion of Cu into the scale. 3. Silicon additions decrease the wüstite fraction indicating a decrease in the Fe cation diffusivity in the wüstite phase. 4. Due to the decreased parabolic oxidation rates and formation of fayalite at the metal oxide interface but lack of significant occlusion, the mechanism behind the reduction of the Cu-rich phase for these low Si contents is the formation of Si-oxides in the scale impeding the transport of Fe cations, therefore reducing oxidation of the steel and enrichment of Cu at the interface. 5. Si-oxide formation in the scale around the wüstite grains and along the interface was identified in the Si-containing samples using SEM-EDS and XRD, which corresponds with a decrease in ion diffusion therefore a reduction in oxidation and corresponding hot shortness.