Oxidation Behavior of MoSi 2 -Coated TZM Alloys during Isothermal Exposure at High Temperatures

摘要

Coating properties and oxidation behaviors of Si pack cementation-coated TZM (Mo-0.5Ti-0.1Zr-0.02C) alloys were investigated in order to understand the stability of the coating layer at high temperatures up to 1350 °C in an ambient atmosphere. After the pack cementation coatings, MoSi 2 and Mo 5 Si 3 layers were formed. When MoSi 2 -coated TZM alloys were oxidized in air at high temperatures, the Si in the outer MoSi 2 layer diffused and formed SiO 2 . Also, due to the diffusion of Si, the MoSi 2 layer was transformed into a columnar shaped Mo 5 Si 3 phase. During isothermal oxidation, the Mo 5 Si 3 phase was formed both within the coated MoSi 2 layer and between the MoSi 2 and the substrate. The coating properties and the oxidation behavior of the Si pack-coated TZM alloys were discussed along with the identification of growth kinetics.