Siliconizing of Iron by Molten Magnesium-Silicon Alloy Bath

Abstract

A molten magnesium-silicon alloy bath containing 1 to 12 mass% of silicon was used for siliconizing iron by keeping the specimen in the bath for 180-900s at 973-1123K. The composition of siliconized layer, which consisted of fine-grained and columnar-grained sublayers, was identified almost the same as Fe₃Si, using the Energy Dispersive Spectrometer and the X-ray Diffractometer. Micro-Vickers hardness number of the layer was about 500. The thickness of the layer varied with the siliconizing temperature and time. Then the diffusion coefficient was calculated as,
D=1.91×10^-4exp[-152.6(kJ/mol)/RT] (m²/s) for Mg-3%Si alloy bath, and
D=4.54×10^-4exp[-163.5(kJ/mol)/RT] (m²/s) for Mg-12%Si alloy bath.
On the growing way of the columnar-grained sublayer which is thicker than the fine-grained sublayer, insoluble particles deposited on the surface of the specimen can be taken and dispersed into the layer by this siliconizing process.