![Sample our Physical Sciences journals, sign in here to start your FREE access for 14 days]({"type":"image" , "src" : "/sda/110819/TOC-Subject-Sample-2021-Physical-Sciences.jpg"})
Abstract
The oxidation behaviour of a commercial Fe–Cr alloy with 22 wt% Cr was investigated at 1173K in Ar–9 H2 with 1% H2O (pO2 = 9.8 × 10−19), in air with 1% H2O (pO2 = 0.208), and in a combination of the two atmospheres. The oxide morphology was investigated with X-ray diffraction and scanning electron microscopy. The oxide layer consisted of MnCr2O4 on top of Cr2O3.
Small oxide whiskers were present at the surface after oxidation in Ar–9 H2 with 1% H2O but not after oxidation in air with 1% H2O. For samples initially oxidised in air with 1% H2O, the oxide/alloy interface was wrinkled and covered with a SiO2 layer. SiO2 particles had developed at a rather flat oxide/alloy interface for samples initially oxidised in Ar–9% H2 with 1% H2O. The results obtained can be explained assuming that oxide growth occurs by cation diffusion only in Ar–9 H2 with 1% H2O, whereas both cation and anion diffusion contribute to the growth in air/H2O.
