Classification of Oxidation Behavior of Disilicides

摘要

This study focuses on classification of structures of oxide scales formed on disilicides. The oxide scales formed on disilicides can be grouped into 3 types, (a) silica scale, (b) mixed oxide (silica+metal oxide) scale, and (c) double layered (silica/metal oxide) scale. Disilicide that forms an oxide scale of the type (a) generally show excellent oxidation resistance. As such disilicides, there are FeSi_2, CoSi_2, MoSi_2, WSi_2, etc. In FeSi_2 and CoSi_2, a protective silica scale must be formed due to the selective oxidation of Si, whereas in MoSi_2 and WSi_2 evaporation of metal oxide plays an important role for the formation of a silica scale. Oxidation of TaSi_2 and NbSi_2 belonged to the type (b), and only CrSi_2 the type (c).