Low temperature oxidation of Cr-alloyed MoSi2

Cr-alloyed MoSi2 was compared with monolithic MoSi2 with respect to oxidation at 450°C for 456 h. Phases formed on Cr-alloyed MoSi2 after exposure are Cr2(MoO4)3, MoO3, and cristobalite (SiO2) according to X-ray diffraction results. Monolithic MoSi2 forms MoO3 and mainly amorphous SiO2. X-ray photoelectron spectroscopy indicates that the main oxidation product on the outermost surface is SiO2 for all studied samples. The samples form a relatively loose oxide but the oxide adherence improves with increasing Cr content. It is indicated that Cr addition can benefit pesting control in MoSi2.